The Northwest Wind of Fall...

By: Zachary Labe , 9:56 PM GMT on September 26, 2009

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"Afternoon Thoughts"(Updated 9/26)
Looking back at the past year in weather across the Northeast, I find it hard to pinpoint any storm of any significance. Not that this is a bad thing, as the relatively quiet in nationwide weather is probably better for the economy; but it is interesting how benign the weather pattern really has been. Yes there have been several extreme weather anomalies, for instance take the recent Atlanta metro flooding with up to 19inches of rain, but looking on a large-scale level it is hard to find much. Fortunately hurricane season 2009 was extremely quiet as expected with only some minor impacts to the United States coastline. Looking at the overall pattern, it appears most tropical activity is going to continue to quiet down so hopefully those along the coastline can continue to breath a sigh of relief. Even the winter of 2008-2009 featured hardly anything of record, perhaps just a short January arctic blast with a day of negative lows but again nothing of too much memory. Large-scale storms were hard to come by even causing the winter to be one of the driest on record for the Middle Atlantic. Then as we entered Spring, Vortex2 sent out there mission of tracking and researching tornadoes; but we have one of the quietest tornado seasons in recent memory this year. Then Summer comes along with well below normal temperatures for most of the country. Sure the Texans would not agree with that statement, but looking on a widespread level and not pin-pointing extreme weather anomalies, hot/hazy/humid weather was hard to come by. And then as earlier mentioned we enter hurricane season, which turns into the quietest in recent record. Now I suppose we are fortunate to have the lack of extreme weather, but it sure is interesting how quiet the pattern has been. I wonder when this will change? In any case I guess I cannot call the Lower Susquehanna Valley this year "where storms come to die," because the entire country has been lacking in storm activity. In any case as Joe Bastardi always says, "Enjoy the weather! It's the only weather you've got!"

"Regional Advisories"

(Courtesy of NOAA)

"Current Weather Map"

(Courtesy of Wunderground)

"7-Day Forecast Discussion"(Pennsylvania, Maryland, Delaware)(Updated 9/26)
Relatively high confidence forecast this week looks likely with a bit of active weather earlier in the week transitioning to cool and dry weather later in the week. 1000mb low pressure will be moving up through the Ohio Valley across the Northern Middle Atlantic overnight Saturday into Monday. A moderate 35knot low level jet and isentropic lift will allow plentiful moisture to development streaming northeast from the Gulf of Mexico. PWATs will rise to near 1.75inches which is 1-2STD deviations above normal. GFS in particular shows a period of moderate to heavy Saturday night across the entire region, but especially southern Pennsylvania through Maryland and Delaware. At times Saturday night rainfall rates will approach .5inches per hour as the low level jet strengthens. Water vapor loops and current visible satellite already show a large expanse of clouds and moisture aloft with a dense stratiform stratus cloud deck dropping conditions to IFR conditions Saturday with ceilings as low as 300ft. Moderate low level shear will also promote some breezy conditions Saturday out of the south-southwest near 15mph. With low stratus and widespread rain with RH values near 100%, low temperatures Saturday night will not drop too much from dewpoint values in the mid to upper 50s with low 60s for Washington DC. Rainfall will continue much of the night as the low progresses east-northeast out towards the Atlantic Sunday morning. Rainfall totals will be moderate soaking rainfall with 1-2inch totals over the entire Middle Atlantic. The heaviest rainfall totals will likely be over western Maryland and the southern Laurel Highlands where orographic lift will enhance rainfall rates overnight. A few timing discrepancies arise between the models for the end of the stratiform rain, but for most areas it appears the rain will be done by 12pm-1pm with scattered alto-stratus clouds through the rest of the day and occasional drizzle over northeastern Pennsylvania in the Poconos. Under a southwesterly flow ahead of a negatively tilted trough, highs will rise warmer than Saturday in the mid to upper 70s for areas in Maryland, Delaware, and southern Pennsylvania with highs in the low 70s along and north of interstate 80. H85s rise to near 13C and with a few peaks of sunshine, an 80degree high or two cannot be ruled out especially for the major metropolitan region. Inversion should maintain low ceilings over the mountains throughout the day as low as 500ft (MVFR conditions). Skies remain mostly cloudy through the evening into Sunday night as an advancing steep trough moves through the Ohio Valley. A few areas of clearing may develop, especially in the east to perhaps aid in fog development. A linear vertical change in humidity aloft though will be partial to stratus development and not fog, but a few areas of dense fog (.25mile visibility) cannot be ruled out overnight Sunday. With high RH values over 75% and mostly cloudy skies, lows will again not drop off too much generally into the low 60s for most of Delaware and Maryland with upper 50s for most of Pennsylvania and far western Maryland. Monday features an interesting day with our first true Autumn front. Crashing H85 heights below 10C accompanied by a steep trough and tight pressure gradient will allow for a strong cold frontal passage with gusty winds and possible rain showers. Veering wind profiles aloft and moderate low level shear with helicity values near 534 m2/s2 during Monday will cause the potential for an isolated strong wind gust over northern Pennsylvania. A strong upper level low, 984mb, advancing quickly through Quebec and Ontario will be the catalyst for the gusty winds. Looking at convective indices, CAPE values only rise to near 50 j/kg profiles for most of the region. Areas south of I-80, away from the better dynamics will escape with only rain showers and an isolated thunderstorm. A low-topped squall line is highly possible Monday morning from New York State south through extreme northern Pennsylvania. 0-6km shear values approach 60knots and any higher core thunderstorm that forms could mix down some gusts of 50mph to the surface especially towards the Great Lakes. QPF totals will only be near .25inches for most areas with only a frontal rain band. A weak thermodynamic field should inhibit most thunderstorm development under a moderate CIN environment. At this time I am not too concerned for the Middle Atlantic, with any squall line probably limited towards New England. Monday will generally featured rain showers immediately along the front with partly to mostly alto-cumulus clouds throughout the day. Highs will be in the low 70s for most all areas dropping steadily with a frontal passage for western Pennsylvania around 8am, 12pm for central Maryland and Pennsylvania, and after 3pm for the rest of the area. A 277degree cyclonic flow will presume after the frontal passage for Monday night with breezy conditions under the tight pressure gradient. Gusts above 1500ft will be near 35mph with gusts in the valleys near 25-30mph. Dewpoints will be on the fall also Monday along with temperatures with lows chilly near 39degrees for extreme northern Pennsylvania with lows in the 40s for most of central, northeastern, and western Pennsylvania. Lows for Maryland and Delaware will be slightly milder courtesy of the later frontal passage with lows in the 50s to near 60 for Baltimore and Washington DC.

Tuesday will feature a cyclonic northwest 314degree flow with a bit of lake effect precipitation for far northwestern Pennsylvania. Lake temperatures in the 70s with highs in the 50s up in that region will promote some scattered rain showers with QPF generally at or below .1inches. Much of Tuesday looks to remain typical of a northwest flow with widespread clouds over the mountains and some clearing to the east courtesy of downsloping. Highs will be near 10degrees below normal with H85s around +2C. Across central Maryland and all of Delaware highs will be in the mid to upper 60s including Washington DC. Across western Maryland up through western and central Pennsylvania highs will range from the upper 50s to low 60s. For northern Pennsylvania highs will be in the mid to upper 50s with a few low 50s possible across Potter and McKean Counties. Tuesday night will feature mostly cloudy skies over the region with a semi-relaxation of the gusty winds from 20mph down to 10mph. Lows will range in the 40s for most areas north of the Baltimore-Philadelphia corridor. Across areas south of that line lows in the 50s will be the common place. Wednesday will feature a reinforcing shot of cold air as a closed 500mb low moves through southern Canada with a weak-undefined cold front draped through the Northeast. This will allow for the coldest air of the season with H85s dropping at or below 0C through the Mason-Dixon Line. Highs Wednesday will be similar to Tuesday's highs in the 50s and 60s for all areas under partly to mostly cloudy skies. Once again a few lake effect rain showers will cause a few hundredths of an inch of rain in the northwestern parts of the state. But also a few rain showers could be across the rest of western and central Pennsylvania associated with the advancing shortwave. Wednesday night will feature an advancing eastward Anti-cyclone, which will allow for clearing skies for much of the Middle Atlantic. But up across northern New England, the Adirondacks, White Mountains, and Green Mountains will likely pick up the first snow of the year. Typically in late September and early October H85s must be around (-4)-(-6)C for snowflakes, and that looks possible towards the mountains with an upslope orographic lift event. Elevations above 4000ft may pick up a coating to inch of snow overnight, so for those in the region you may want to check out the peaks especially towards Mt. Mansfield early Thursday morning. Lows Wednesday night for the Middle Atlantic will range from the mid 30s over northern Pennsylvania to low 50s near Washington DC. The cold pool aloft centers itself over the region for Thursday with the associated high pressure, 1024mb. With H85s below 0C through most of the Middle Atlantic a few cold nights are certainly in store. Thursday will feature sunshine generally over the entire region with a few clouds over the higher elevations of western Maryland and Pennsylvania about 1700ft. With dewpoints in the 30s over the entire region, it will feel pretty chilly with highs in the mid 50s for northern Pennsylvania up to mid 60s for southern Maryland and southern Delaware. Thursday night will be the coldest night of the young season with dewpoints in the 30s with clear skies and calm winds ideal for radiational cooling. Lows will likely fall at or below freezing for the northern parts of Pennsylvania with patchy frost in the I-80 corridor. Lows in the upper 30s to low 40s are expected elsewhere. I would not be surprised though if these low numbers get colder with frosts as far south as the Pennsylvania turnpike and northern Maryland near Garret County. After some patchy morning fog and frost Friday morning, sunshine will prevail through the afternoon with once again well below normal temperatures. Highs will be in the upper 50s to upper 60s throughout the region. Once again ideal radiational cooling conditions for Friday night, but a few clouds, cirrus, may try to work in late overnight. Still frosts are possible on a widespread level with lows ranging from 30-45 over the Middle Atlantic.

"Regional Radars"

(Courtesy of Wunderground)

"Regional Satellite"

(Courtesy of Penn State Meteo.)

"Lower Susquehanna Valley Forecast"(Franklin, Adams, York, Lancaster, Cumberland, Perry, Dauphin, Lebanon Counties)(Updated 9/26)
Well below normal temperature week is in store for the Lower Susquehanna Valley along with a decent soaking rain. Increasing moisture from the Gulf of Mexico associated with a low pressure system moving across northern Virginia will allow for a period of moderate to heavy rain Saturday night. Increasing boundary layer southeast winds will allow moisture to pile up along the southern facing ridges causing low clouds with ceilings as low as 300ft and patchy fog, visibilities around 3-5miles. Also some stronger winds aloft may cause it to be a bit breezy during the rain making it feel quite chilly outside Saturday night through early Sunday morning. Lows Saturday night will be similar to dewpoint values in the mid to upper 50s over the valley with a few colder numbers for elevations above 1000ft in northern Dauphin and Lebanon Counties along with Franklin and Adams Counties. Rainfall amounts will be a widespread 1-2inches over the region with highest totals along South Mountain courtesy of the favored upslope enhancement. Rain should be ending by early Sunday morning as the low pulls off to the northeast across Long Island on off the coast. Under a more southwest flow Sunday conditions will try to improve, but with an inversion stratus clouds may be hard to budge especially during the first half of the day. With slightly rising temperatures aloft, highs will be several degrees warmer than Saturday rounding out in the upper 70s near York and Lancaster to mid 70s from the Pennsylvania turnpike corridor on northward. Mostly cloudy skies will prevail most of the day with patchy morning drizzle and fog. Any additional rainfall will be light and generally less than a tenth of an inch. Sunday night will feature partly cloudy skies over the region with a slightly southwest breeze ahead of a steep south-north facing trough advancing east from the Great Lakes. Coupled with a strong upper level low in Canada, the cold frontal passage will be the first to pose more Autumn characteristics. But overnight Sunday lows will be in the mid 50s throughout much of the Lower Susquehanna Valley, which is actually a tad above normal. Monday will be the cold front passage around noon with a chance of a low-topped rain shower squall line that may pull some of the gusty winds aloft to the surface. Best dynamics remain north of Harrisburg though in this instance. In any case the narrow precipitation frontal band should only cause a little bit of rain with amounts no more than .25inches. As the front moves through temperatures will slowly fall Monday with highs ranging from low 70s over Franklin, Cumberland, Adams, and Perry Counties to mid 70s over Lancaster and Lebanon counties. Breezy conditions will prevail by evening courtesy of cold air advection and the northwest flow. Monday night will be a bit breezy and partly cloudy with lows ranging from upper 40s in northern Perry, Dauphin, and Lebanon Counties to low 50s for Lancaster County. Winds should not exceed 25-30mph for the most part. Tuesday will feature a typical northwest flow with partly cloudy skies over the eastern parts of the Lower Susquehanna Valley courtesy of downsloping, but clouds over the western half especially in Franklin County. Highs will slowly rise throughout the day and struggle to reach the 60degree mark for elevations above 900ft. The cities of Harrisburg, York, and Lancaster will see highs in the low to mid 60s. Tuesday night the winds will finally begin to settle and skies will slowly clear ahead of another advancing shortwave. Lows will be in the mid to upper 40s over the region with dewpoints in the low 40s or perhaps upper 30s over northern and western Perry County.

Wednesday features the cold pool aloft centering over the Northeast as another shortwave in Canada accompanies a weak undefined cold front that will move through during the day. H85s heights will drop below 0C causing the coldest conditions of the season. Partly to mostly cloudy skies will occur Wednesday over the Lower Susquehanna Valley with a chance of a few spotty rain showers. Precipitation totals generally though will remain at or below a tenth of an inch. Highs will be in the upper 50s to low 60s over the region. Wednesday night conditions begin to clear out for a cold night as winds decouple towards the pre-dawn hours of Thursday allowing lows to dip into the low 40s for the northern half of the valley with mid 40s for areas in Lancaster and York County. Mostly sunny skies will prevail Thursday after some patchy morning river fog that will form near the Clarks Ferry Bridge courtesy of the extreme water/air temperature contrast. Thursday will be a beautiful Fall day with highs in the low to mid 60s over the region with brilliant sunshine. Dewpoints will drop into the 30s by evening as winds will relax as high pressure approaches from the west. Thursday night will feature the coldest conditions so far with lows possibly into the mid to upper 30s especially north of the Pennsylvania turnpike. Depending on dewpoints, frost may be possible for some areas, but I will have updates throughout the week as the threat becomes closer. Friday again features a beautiful day with well below normal temperatures continued under brilliant sunny skies after patchy morning frost and radiation fog. Friday night will feature clear skies for the first half of the night with increasing stratus overnight ahead of the next shortwave/front combo for Saturday. Lows will be very cold Friday with even some guidance printing out lows in the low 30s. Again I will focus in more on this threat later in the week.

"Current Lower Susquehanna Valley Radar"

(Courtesy of Wunderground)

"Chesapeake Bay and Atlantic Coast Marine and Boating Forecast"(Maryland and Delaware Coastal Forecast)(Updated 9/26)
It does not look like the best week for marine interests with several days of small craft advisory thresholds. A low pressure will move across northern Virginia and out to sea through Sunday afternoon. Low level wind shear will allow breezy winds to mix down to the surface with gusts over the Chesapeake Bay near 25knots through Sunday evening. Heavy rain will also occur with QPF totals near 1-1.5inches. Conditions will remain very poor through Sunday evening. Areas of advection fog may also form off the Atlantic coast a few nautical miles along with wave heights up to 6-8ft just offshore. Winds may approach 30-35knots along the Atlantic Ocean coastline through Sunday evening. Along the heightened waves and wind, the southeasterly flow will cause some coastal flooding as the southeast flow channels the water up the Chesapeake during high tide Saturday night through Sunday night. Prone splash-over areas may see tidal levels up to 2ft above normal. Monday another cold front approaches the region with a strong tightened pressure gradient causing an extension for small craft advisory conditions. An isolated thunderstorm is also possible along with spotty rain showers associated with the frontal passage. Winds will approach 30knots over the water Monday and this will last through Tuesday. The flow will turn more northwesterly allowing any coastal flooding to end by Monday morning. But wave heights and winds will remain in moderate levels for Fall standards through Tuesday evening. Another weak shortwave approaches the region Wednesday causing much colder conditions and breezy conditions again, but for now it looks like conditions remain below small craft advisory thresholds. Thursday and Friday, an anti-cyclone will allow for a relaxed pressure gradient with calmer seas and wind, but temperatures will be chilly with overnight lows in the 40s for coastal waterways. Water temperatures are just about now beginning their turn-around slowly cooling each week. By the weekend it appears a weak front approaches the Middle Atlantic, but nothing overly threatening looks likely.

"Current Atlantic Coast Forecast Wave Heights and Chesapeake Bay Forecast Wind Direction/Speed"

(Courtesy of NOAA)

"Updates on Winter Predictions" (Updated 9/26)
This section has been recently added this week and will last through the month of October is replacement of the Garden/Agriculture section. This section allows me to keep updating how the ENSO is evolving and the northern Pacific situation. Also we will be able to see how conditions are presenting themselves in contrast with my winter forecast. By the way this year I have decided not to issue an updated winter outlook forecast like I did in 2008. Anyways interesting conditions are occurring across the equatorial Pacific which will make this winter one for the analog books. We have a present El Nino with +.75-1C anomalies across the ENSO regions. But what makes this +ENSO interesting are the indices completely promoting a contrasting appearance. For nearly the month of September the SOI readings have been negative more indicative of a La Nina than El Nino, which proves very interesting. Also with unusual QBO, ONI, and GLAAM readings that seem to support Nina, it is surprising to watch each day. While yes there will be fluctuations from time to time and yes people are quickly overreacting, it is so interesting how the name La Nina keeps on coming back. If we look back at last winter and even the Summer 2009, La Nina unexpectedly dominated the global weather pattern regime. And even this Fall there are a few slightly noticeable lingering La Nina effects in the Pacific. Now I am not saying a La Nina is coming this winter, but I am just throwing some ideas on the plate. Also it is interesting to look at the latest ENSO regions with cooling SST positive anomalies in regions 1+2, 3; but regions 3.4 and 4 have remained relatively steadfast. This is a sign of the weak footing the El Nino has, but also a sign the El Nino is still approaching being west based and not basin wide which is in correspondence with the forecast. Finally I want to mention the PDO. This is my biggest concern this winter as there are some select signs already that there may be a blasting Pacific jet. A large cold pool in the Gulf of Alaska is showing up on SST anomaly charts which is indicative of a negative PDO. But a few positive anomalies on the southern edge of the pool gives me hope that the PDO will not be as negative as last winter. Now these thoughts above are only really thoughts at this point as winter is an "educated guessing game." But one thing for sure is this winter is not going to behave strictly like any analogs. I can see reason for people to fear a warm winter again, but for now I do not see any reason for alarm. In the end I suppose Mother Nature will do what she wants to do.

Winter Outlook 2009-2010...Link

"Equatorial Pacific SST Anomalies"

(Courtesy of NOAA)

"Average Date of First Freeze"

(Courtesy of NOAA)

"Fall Foliage Outlook" (Updated 9/26)
Ah next week is the start on one of my favorite months of the year, October. It is amazing that we are already almost a week into the official start of Fall and that some areas are seeing peak fall foliage. Looking first at Pennsylvania, northern Pennsylvania is seeing decent color courtesy of very chilly nights and a few frosts. Fall color in the maples is nearing peak in the week or two for elevations above 2200ft across Potter and Tioga Counties. Wildflowers are also in full bloom for northern Pennsylvania, but also region wide. Oaks are beginning to show some signs of yellows across northern Pennsylvania with invasive species and ornamental trees across northern Pennsylvania at or past peak. Brilliant oranges and reds will be likely by next weekend near the Pennsylvania Grand Canyon outside of Wellsboro. For those who have never ventured up that way, it is well worth the trip. Towards the central third of Pennsylvania including the Laurel Highlands, Ridge and Valley region, and the southern Poconos aspens are beginning to turn yellow along with birch across the coal country. Suburbia maples have turned red or showing signs, but mountains generally remain patchy with only some lighter greens, browns, or light yellows appearing in the Ridge and Valley Region. For the Laurel Highlands colors are decent with maples and even oaks beginning to show color. Peak fall foliage will likely be by the end of the first full week in October. The mountains of the Poconos are also showing color, but still have a bit before peak. Across the southern Pennsylvania color is a bit more spotty than the northern neighbors, but colors are still a few days to a week or two earlier than normal. Colors are now slightly evident showing on higher ridges, especially towards the western facing side of South Mountain. Peak fall foliage is looking likely for this region by mid October. For the Philadelphia region through Delaware and central/southern Maryland fall colors are very spotty, but now a bit more color is showing than just distressed and diseased trees. Sumac and other invasive species are turning red and ornamental trees are showing signs of color change. Maples are beginning to show small signs of reds and oranges, but oaks have quite a bit in this region before color change with peak fall foliage likely around late October this year. Finally western Maryland around the Garret County region or so is showing brilliant fall colors for the higher elevations and the next two weeks look wonderful for a drive out to this region. Maples and even oaks are showing through the mountain sides and farm country. Overall this week will allow for more evident color change by next weekend with very chilly nights and below normal temperatures all week. Also Thursday and Friday with the cold nights and sunny days will allow for the chlorophyll to break down in the leaves. Happy Fall!!!

Fall Foliage Reports... Link

"Long Term Outlook" (7-14 Day Time Frame) (Updated 9/26)
Towards next weekend it looks to be generally under a similar theme with below normal temperatures and possibly a weak front passing through the area Saturday, although I do not think it will be too much of a problem for the weekend. It is hard to believe next weekend is the first full weekend of October! Anyways I think the pattern is looking for interesting for the next two weeks. In October we start to see signs of patterns that may hold through the first half of winter. What makes the next two weeks interesting is the impressive west-based negative NAO which will reach its height during the first few days of October and slowly retreat back to neutral overtime. Also impressive above normal 500mb hPa heights are going to be located over the Hudson Bay and western Greenland forming a strong blocking pattern, which again will slowly relax by October 7-10. The pattern appears the first week or two of October is a series of troughs over the east coast with well below normal temperature anomalies and near normal precipitation. Towards mid October the pattern retrogrades as expected, remember my balance of equilibrium theory. With a trough then centered over the Rockies, we still enter a near normal to slightly below normal temperature pattern over the east coast as weak upper level lows rotate through the region courtesy of a negative EPO. As long as the NAO does not stay brutally negative most of the month, historical odds will favor a colder than normal winter as we will have a below normal temperature anomaly for the month. Overall I do not see any extreme warmth headed towards the Middle Atlantic anytime soon. A few bouts of warmer than normal temperatures are likely towards the second to third week in October as a trough forms over the west, but for now that looks temporary with GFS/GEFS means producing a positive PNA by mid month. Generally the pattern is reminiscent of typical slightly below normal temperature Octobers with a volatile pattern with occasional weak mid level ridges followed by quick weak troughs and associated upper level lows.

"Current NAO and PNA Predictions"

(Courtesy of NOAA)

"Monthly Temperature/Precipitation Outlook"(October)(Updated 9/13)
This monthly outlook is going to be posted a bit early this year for October. I never issued a September forecast and now it is the middle of the month so I decided to forecast October instead of the last two weeks in September. Therefore this outlook is a bit lower than normal for confidence. As many probably could guess I am going with a colder than normal October. Long term GFS especially is consistent with trough formation over the east coast and an amplified western ridge. Latest ECMWF is also steadfast, but not amplified with weaker western ridge and a weaker trough, but they are still evident. Teleconnections are a bit more favorable also for a cool pattern across the east coast. It appears the PNA will be spiking highly positive towards October 1 with the NAO and AO more towards neutral. As far as precipitation it appears near normal precipitation is likely with a drier start to the month gradually becoming more active. If the cooler than normal October verifies historical odds definitely favor a colder than normal with quite a bit of snow for the upcoming winter. I guess all we can wish for is not another October 2008 which was extremely mild and again followed by a mild winter. Looking on a more global perspective there is a building dome of cold air over the Arctic towards Greenland and northern Canada. This cold air will continue to build and likely be a catalyst for bits of cold air to break off and surge to the United States with strong cold fronts.

Temperature- As I already mentioned I believe this month will feature cooler than normal temperatures will a general trough over the Middle Atlantic. I think areas north of I-80 will have the colder anomalies as occasional stalled fronts affect southern Pennsylvania, Maryland and Delaware with clouds and precipitation while highs to the north allow radiational cooling for northern Pennsylvania. I am going with a general (-1)-(-2) temperature anomaly for most areas with a generally (0)-(-.5) for the metros of Philadelphia and Washington DC. Frosts and freezes do look likely for most all locations this month with periods of colder than normal weather. Especially early in the month frosts may occur with a high pressure over the region and a trough.

Precipitation- Precipitation looks to be near normal for the month with a dry start to the month as a strong high pressure looks to be over much of the eastern United States in a general benign weather pattern. Towards the middle of the month and the end the active storm track should resume similarities to earlier in the month of September. The subtropical jet will feature periods of storms tracking up the east coast. As far as snowfall, most likely at some point in the month areas, in the lake effect snow belts of Maryland and Pennsylvania will see at least flurries. It is too early to tell whether any system like October 2009 will affect the region.

"Temperature and Precipitation Outlooks from Climate Prediction Center for next 30 days"

(Courtesy of NOAA)

"Here 10mi Northeast of Harrisburg, PA 2009 Statistics"
(Severe Weather Stats...)
Severe Thunderstorm Watches- 8
Severe Thunderstorm Warnings- 9
Tornado Watches- 0
Tornado Warnings- 0
Total Thunderstorms- 33

(Precipitation Stats...)
Flood Watches- 4
Flood Warnings- 1
Monthly Precipitation- 3.69inches
Yearly Precipitation- 32.53inches

(Temperature Stats...)
Heat Advisories- 2
Excessive Heat Warnings- 0
90degree Days- 9
Highest Temperature- 95degrees

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117. TheRasberryPatch
8:08 PM GMT on October 01, 2009
Thanks for the update Blizz. that should be good. The inlaws are going to do Gettysburg on Saturday - do a driving tour and Harpers Ferry and Antietam on Sunday. Glad the weather is improving.

That winter you showed the graph was cold, just not any moisture
Member Since: January 26, 2007 Posts: 72 Comments: 6256
116. Zachary Labe
7:25 PM GMT on October 01, 2009
TheRasberryPatch- By the way, it looks like this weekend is looking a bit nicer. It appears the rain will not be as much as originally thought in my blog above. Friday night looks to be most of the rainfall which shouldn't be too much. Saturday it appears the second half of the day may be nicer. Still though keep an eye on the changes.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
115. Zachary Labe
7:15 PM GMT on October 01, 2009
Quoting TheRasberryPatch:
TDW - i think you are mistaken it for the winter of '01-'02. that winter was dry. i don't think we had much snow that year.

here is a link of the history for the area i am speaking about. Link

Snowfall for 2001-2002... Link

Barely over 45inches even in the northwest snow belt of Pennsylvania. Single digits across southern Pennsylvania.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
114. TheRasberryPatch
7:11 PM GMT on October 01, 2009
TDW - i think you are mistaken it for the winter of '01-'02. that winter was dry. i don't think we had much snow that year.

here is a link of the history for the area i am speaking about. Link

i think '04-'05 that area got clobbered with big storms
Member Since: January 26, 2007 Posts: 72 Comments: 6256
113. Zachary Labe
6:55 PM GMT on October 01, 2009
Jmedic- Good afternoon! The PDO is a decadal cycle which we are probably towards the end of the cycle. The anamalous La Nina from two winters ago was one of the strongest on record so we remain in a remnant pattern of the La Nina this past summer. But now things are transitioning to a weak El Nino and an eastly wave burst and Kelvin wave should enhance the other indices more similar to El Nino status. This will likely mean a chilly October and snowy winter ahead looking back as past historical records. But keep in mind every year is different and this El Nino is a bit atypical. Thanks for stopping by!

Mt. Washington webcam...
Member Since: December 14, 2007 Posts: 284 Comments: 15112
112. TheDawnAwakening
6:21 PM GMT on October 01, 2009
Hmm, then I must be thinking of the 2001-2002 winter. I remember one of these winters we saw a parade of storms just form over the open ocean and just skirt by with some clouds and some snow showers. We were forecasted to have 15" of snow with a winter storm warning and then the next morning school was cancelled and all we got was a few inches of snow. It turned out we had two of those storms and they both went far out to sea with minimal impact at the most. That winter was very cold and dry. 2000-2001 I must have been referring to Cape Cod, MA winters. Do you have any links that I could get for individual counties for a state for climatology records and what not?
Member Since: October 21, 2008 Posts: 245 Comments: 3901
111. TheRasberryPatch
3:47 PM GMT on October 01, 2009
a rather cold morning. 52F @ 1130am

TDW - i must say that winter 2000-01 was rather wet. i was in Orange County, NY just 55 miles NW of NY city and we got killed by snow all winter even into April. Now, NYC didn't get all that snow, but they got rain. It was pretty amazing. My wife worked in Englewood Cliffs, NJ next to the GW Bridge and it would be raining there but snowing 50 miles away and she couldn't take The Palisades home too hllly icy and windy
Member Since: January 26, 2007 Posts: 72 Comments: 6256
110. NEwxguy
2:54 PM GMT on October 01, 2009
I had a low of 39 degrees this morning
Member Since: September 6, 2007 Posts: 878 Comments: 15739
109. TheDawnAwakening
2:50 PM GMT on October 01, 2009
While most of our winter weather systems come from the west, I would expect the SST anomalies off the East Coast of the US associated with the Gulf Stream would be more important to storm track then say the ENSO phases. The gulf stream directly affects the process of an explosion of the low and its precip because of the amount of energy stored in the ocean and warmer oceanic temperatures. The storm could tap into this well of warm water while tapping into the cold freezer the Northeast has to offer. A +PNA and + Gulf Stream SST anomaly would have more barring on the strength and position of the storm track compared to the orientation of the ENSO phases. One would think that the Atlantic Ocean would have more say on our winter weather then the Equatorial Pacific ocean. The thermal gradient between the +PNA supporting an arctic airmass over the Northeast and the positive temperature anomaly of the Gulf Stream would have more say because of its effects on storm track and potential intensity. Say for hypothetical reasoning, that the Gulf Stream was colder this winter than average and the PNA was positive: this would support a cold and dry winter like we have seen in 2000-2001 and 2001-2002 because the storm track would be suppressed all the way out to sea to just give the region a dusting of snowfall. Now say that the direct correlation is true, and that we a warmer than average gulf stream and a positive PNA, now the storm track would come further west by 100 miles or so, because of the varying temperature or thermal gradient of the ocean and air fueling to process of explosive deepening of an extratropical cyclone like we saw with the 12/26/2004 snowstorm and the Blizzard of 2005. In both cases the SST anomaly with the gulf stream was 4C over average and the PNA was positive. This warm water of 4C over average could have been enough to focus the track of the storms further west and north, then say the colder seasons. The region to look for these SST anomalies would be -80W to -60W longitude and 40N latitude. Why this region? Because this region would have more to do with coastal New England snowfall then say the Mid Atlantic.
Member Since: October 21, 2008 Posts: 245 Comments: 3901
108. Jmedic
2:34 PM GMT on October 01, 2009
Ok, I have a question. I am trying to understand SST anomalies and their effects on climate and weather, particularly for us here in Western Pa. From everything that I've read la nina years typically correspond to a negative PDO and el nino years a positive PDO. As it looks now the current SST anomalies are showing a mild/moderate positive ENSO and yet a negative PDO.

Is this a typical transition period? Also, what might that mean as far as prevalent weather patterns in the mid-atlantic US?
Member Since: October 14, 2006 Posts: 0 Comments: 98
107. TheDawnAwakening
12:14 PM GMT on October 01, 2009
Mt. Washington is some 30-60 minutes north of my college. I don't drive, so it will be hard to get up there at some point. Great statistics Blizzard. That just goes to show that winter is on the way.
Member Since: October 21, 2008 Posts: 245 Comments: 3901
106. TheRasberryPatch
11:47 AM GMT on October 01, 2009
low of 43F

Member Since: January 26, 2007 Posts: 72 Comments: 6256
105. Zachary Labe
10:32 AM GMT on October 01, 2009
Mt. Washington 24hr statistics...

Maximum Temperature: 34°F

Minimum Temperature: 21°F

Peak Wind Gust: W 52 mph

Average Wind Speed: 21.1 mph

Liquid Precipitation: 0.25"

Snowfall: Trace
Member Since: December 14, 2007 Posts: 284 Comments: 15112
104. Zachary Labe
10:08 AM GMT on October 01, 2009
Winds never quite decoupled here so only a low of 45. But some areas did get pretty chilly. It appears once again the areas in northern Pennsylvania did not dip below freezing so the contest continues. Tonight should be a bit chillier for some areas, but across the north clouds will limit radiational cooling more than the south.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
103. originalLT
4:28 AM GMT on October 01, 2009
44.6 degrees, clear, calm winds, baro 29.94" rising slowly. Stamford CT.
Member Since: January 31, 2009 Posts: 0 Comments: 7522
102. Zachary Labe
2:03 AM GMT on October 01, 2009
TheRasberryPatch- Not it wasn't terribly cold by any means, but really that is courtesy of the consistent upper level lows that move in with the troughs. To get the real cold nights you need a high to move in after the cold front. By the way down to 47.9degrees already.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
101. TheRasberryPatch
1:29 AM GMT on October 01, 2009
one thing i noticed...i haven't had to put on the heat at all so far, of course this evening may change that.

i used to try and see if i could wait until October 1st. of course its always possible, but with young kids its not necessary. anyway, even though September may have been cooler than normal it hasn't been real cold. just an observation

temp is 48f with a dewpt of 42.6f
Member Since: January 26, 2007 Posts: 72 Comments: 6256
weathergeek5- Thanks for pulling them up! Here is everyone's name for those locales...

KTHV (York-Thomasville, PA)...
Mason803- September 30
Blizzard92- October 4
Snowlover2010- October 5
wxgeek723- October 7
Lawntonlookers- October 14
TheRasberryPatch- October 15
hurricane30- October 17
Tazmanian- October 20

KMDT (Harrisburg-Middletown, PA)...
Snowlover2010- September 30
Blizzard92- October 7
TheRasberryPatch- October 8
wxgeek723- October 11
hurricane30- October 17
Lawtonlookers- October 21
Mason803- October 22
Tazmanian- October 30

KBFD (Bradford, PA)...
Snowlover2010- September 15
Mason803- September 18
hurricane30- September 18
Blizzard92- September 22
TheRasberryPatch- September 23
Lawtonlookers- September 28
wxgeek723- September 30
Tazmanian- October 1

KPIT (Pittsburgh, PA)...
Snowlover2010- September 28
Mason803- September 28
Blizzard92- October 1
Lawtonlookers- October 5
TheRasberryPatch- October 6
hurricane30- October 12
wxgeek723- October 14
Tazmanian- October 20
Member Since: December 14, 2007 Posts: 284 Comments: 15112
here are the contest cities for the northern areas:

KTHV (York-Thomasville, PA)...
Mason803- September 30


KMDT (Harrisburg-Middletown, PA)...
Snowlover2010- September 30

KBFD (Bradford, PA)...
Snowlover2010- September 15


KPIT (Pittsburgh, PA)...
Snowlover2010- September 28
Mason803- September 28


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Looks like a very cold night. Dewpoints already in low to mid 40s, just wait until those winds decouple and see the temperature plumit.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
Blizzard, according to Sully the 04-05 winter was a weak El Nino, not sure because I saw during some research that for there to be an El Nino it has to have SST of 1.5C or great anomalies. However 2004-2005 winter was in a warm seasonal phase for the three month periods of NDJ, DJF and JFM.
Member Since: October 21, 2008 Posts: 245 Comments: 3901
after starting the day with a low 52.7, I only reached a high of 59!
high of 61F. it is now 58F
Member Since: January 26, 2007 Posts: 72 Comments: 6256
Quoting NEwxguy:
Love this winter talk as it approaches,you guys come up with some great data.
What a day,not even going to hit 60 today

We had a max here of 63degrees, but now it is 57.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
Love this winter talk as it approaches,you guys come up with some great data.
What a day,not even going to hit 60 today
Member Since: September 6, 2007 Posts: 878 Comments: 15739
***Looks like time to get out our freeze contest for tonight and especially tomorrow night. I do not have time right now, but will be back on around 8pm to check it.

TheDawnAwakening- Alright thanks for clearing up 77-78, I thought it was neutral just was not sure.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
The 1977-1978 winter was indeed in neutral ENSO phase. The water temperatures of the 3.4 Nino region did not reach 1.5C instead they were .5 to .8 range indicating a neutral phase. A neutral phase was also found in the record breaking winter of 93-94 for Cape Cod, MA and 04-05 in another record breaking winter which we broke the 93-94 winter record for total snowfall. It was most likely due to the suppressed Pacific jet which found its way over the Gulf of Mexico, with a positive PNA and a positive NAO. We had a -NAO most of that winter in 04-05, with the exception of the 05 Blizzard which we saw a +NAO. Likely reason why it didn't stick around like the Blizzard of 78. I will be back this afternoon after classes to converse some more about this winter.
Member Since: October 21, 2008 Posts: 245 Comments: 3901
Thanks Blizz.
Member Since: January 26, 2007 Posts: 72 Comments: 6256
Quoting TheRasberryPatch:
thank you Blizz.

so you think this weekend will be a washout? my in-laws want to come in and see Gettysburg, Antietam and Harpers Ferry.

While it is still a few days away, Satuday is looking wet but possible drier conditions could move in for Sunday. At this point model QPF is ranging from .5-1inch on Saturday.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
thank you Blizz.

so you think this weekend will be a washout? my in-laws want to come in and see Gettysburg, Antietam and Harpers Ferry.
Member Since: January 26, 2007 Posts: 72 Comments: 6256
The 60s and 70s had very amplified pattern, resulting in hot summers and snowy winters. To bad we don't get years like that anymore.

All the years I remeber have cold, dry winters and summers, or hot and dry summers and warm winters. You never get both anymore. The main culprit in my opinion is the stronger blocking high pressure that has been developing in the past decade.
Member Since: October 14, 2007 Posts: 173 Comments: 1372
TheRasberryPatch- The winter of 1977-1978 was one of the coldest winters on record for the United States, I believe it was neutral ENSO conditions but do not hold me to that. As far as the Chesapeake, not sure. I think what is interesting is how snowy the winters were in the 60s and 70s, but yet the summers were also the hottest on record. The summer of 1966 was one of the hottest on record.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
I'm looking forward to whats going to happen this winter,also.This has been such an unusual year for troughs and where they have been setting up,it should make for some interesting weather,at least for the first part of the winter,I still think the pattern is going to change at some point in the winter.
Member Since: September 6, 2007 Posts: 878 Comments: 15739
Blizz - my in-laws in SW Michigan always talk about the winter of '77. they got all kinds of snow (lake effect and regular). any idea what the conditions were like for that outcome?

also, back in the 60's and 70's the Chesapeake used to freeze and they would have to bring in the Coast Guard cutter to break up the shipping lanes. now i realize the Chesapeake is not a deep body of water, but it has not froze since the 70's. do you think it will happen anytime soon?
Member Since: January 26, 2007 Posts: 72 Comments: 6256
The 09-10 winter will probably be a new one for the records. The new data collected from this winter will be very interesting.
Member Since: October 14, 2007 Posts: 173 Comments: 1372
upweatherdog- I agree a bit more with you especially looking at the latest Pacific jet. We may see a large trough across the Midwest through the Northeast. This El Nino is anything but typical, and we probably will not see normal means for +ENSO events. This Nino will probably be a case study by the end of the year with its extremes.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
One thing I have noticed while studying years where New England got large snowstorms is that in many of those years the Ohio valley is dryer than average, and there is another area of above average snowfall over the northern Great Lakes, while the Plains stay dry.

I've noticed in years where the Ohio Valley gets the snowstorms instead of New England, we don't get much snow, but there is a secondary area of higher snowfall around the Red River Valley in North Dakota and Minnesota.

Right now, I predict winter will arrive early for the U.P, with average snowfall U.P wide and slightly above average snowfall in lake effect belts.
Member Since: October 14, 2007 Posts: 173 Comments: 1372
Stanb999- Odds never looked real great anyone. Any flakes will likely be confined in the Adirondacks, Green, and White Mountains Wednesday night.

upweatherdog- Thanks for the link! I will bookmark it!!!

TheDawnAwakening- Great information for all to take in about ENSO effects.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
Likely affects of the PDO, PNA, NAO, AO and AAO seem to disagree alot with varying accounts. In the winter of 2004-2005, we saw a negative NAO with the December 26th, 2004 snowstorm the strongest of the season, but we saw a positive NAO with the Blizzard of 2005. With the rule of thumb normally we getting a negative NAO it is colder and therefore we get a better chance of a snowstorm. However it is possible that in 2005 winter, the Northeast could have seen a lag effect of the weather locally adjusting to the NAO changes. Why do I say that? Now before the Blizzard we were in a negative NAO phase which brought us cold weather with a deep trough over the East and a ridge over the Rockies. This would lead to a positive PNA, which is what we saw as a ridge was in the west and a trough was in the east, now this coincides which is for the most part true. Now the December Snowstorm of 2004 we saw a -NAO and a -PNA. Wierd combination of the two that time. We were technically in a neutral phase of the ENSO that winter. Both 1993-1994 and 2004-2005 winters were in a neutral phase of the El Nino 3.4 region temps while our worst snowfall total of the 12 years of accurate data conclude that 1997-1998 we were indeed well entrenched with a strong EL Nino likely reason we only saw the lowest snowfall that year out of the twelve with 3.3". If we were to have a neutral EL Nino again this winter, and it would coincide with a positive PNA we could be in for a cold winter and snowy one as well. The -NAO would further heighten the likelihood that Southern New England would see higher than average snowfall this winter. A Neutral ENSO phase appears likely as there are signs of both of a La Nina and El Nino present.
Member Since: October 21, 2008 Posts: 245 Comments: 3901
While El Nino regions 4, 3, 2, and 1 are important, they are not the engines that drive this big seasonal changes of El Nino and La Nina. If one was to read one of the EL Nino characteristics, one would know that the EL Nino is known for it's central thunderstorm activity over the central Equatorial Pacific Ocean which would then in turn affect the rest of the Pacific Equatorial regions. So in my opinion it could be that EL Nino region 3.4 is the most important region to watch given its size and reach. Judging by the patterns of warm and cold episodes and the 1997-2009 winter seasonal snowfall pattern for Cape Cod, MA, one could reason that during warm episodes the Cape would get it's biggest snows especially during neutral phases and less snow during the cold phases likely due to a La Nina phase. The circulation of the EL Nino pattern would lead to believe that the SSTs off the SA coast and western Pacific would decrease while the equatorial central Pacific increases therefore owning up to the centralized activity of thunderstorm development and monsoonal rains. So what are the effects it has on the ITCZ in the Atlantic? I really don't have the answer to that. Snowfall map for 2009-2010 winter coming soon in my blog.
Member Since: October 21, 2008 Posts: 245 Comments: 3901
Hey Blizz.

I just found this really good snowfall data map.
Link
Member Since: October 14, 2007 Posts: 173 Comments: 1372
NOAA raised our low temps across the board. We were to get 38 and 35, now it's 37 and 39 for Thursday and Friday respectively. If this continues all thoughts of snow or even graupel seems out of question. :-(
Member Since: September 3, 2008 Posts: 0 Comments: 444
Quoting NEwxguy:
Blizz, looks like a very wet weekend ahead.

Yep that is the only change in my blog above. The weekend is looking a bit more pessimistic than originally thought. Certainly in the overall scheme of things this wet pattern is continuing. Yes there have been a few two week relatively dry periods, but overall since May 2009 it has been well above normal in the precipitation department.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
Blizz, looks like a very wet weekend ahead.
Member Since: September 6, 2007 Posts: 878 Comments: 15739
PalmyraPunishment- Good evening!!! The last two days have extremely heightened my excitement for the prospects of this winter as for once it may appear the Pacific may cooperate. Good luck moving; will you still be in the Lower Susquehanna Valley? Anyways hope to hear from you again soon.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
so, yeah, true story: im perfectly fine with this weather for about 2 months. so if that can stick around (and i know it won't... sigh) and then slowly transition into a nice, cold, snowy winter -- that would be amazing.

i just made the mistake of heading to accucrap's forums (needed a laugh) -- good god. i've never facepalmed so quickly in my life.

so yeah, hope all is well with everybody. i'm getting ready to pack up and move once again so more than likely the next time i sign on for the first winter activity it'll be from yet another location. crazy lol. enjoy the fall!

xpunisherx
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As mentioned above I would detail in on frost potential this week. It appears with the strong northwest cold air advection flow winds may not decouple enough and too many clouds for a widespread frost. A few areas though should see one, but location remains uncertain. For now it looks many areas drop into the upper 30s Wednesday night and Thursday night along and north of the Pennsylvania turnpike and across areas west of the Blue Ridge in Maryland.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
***Raw day with gusts near 30mph with a high of 60 so far and a low of 43.

TheRasberryPatch- Upon some more research of that Lancaster event, there was a coastal low which caused an interesting mesoscale event which link functions from a polar vortex near Erie and frontogenesis along an undefined temporary sea breeze type boundary over Lancaster County. Similar snowfall readings were reported in Chester County but just a few inches less. Now the even that hit yours and my house was more lake effect associated.
Member Since: December 14, 2007 Posts: 284 Comments: 15112
Hi Blizz, I wound up getting .24" more monday night early, as the shower line regenerated and moved thru. Looked like the heaviest moved thru just S of me. Today was sunny earlier, now mostly cloudy, breezy from the WSW. Saw on the Satellite the clouds were moving in.
Member Since: January 31, 2009 Posts: 0 Comments: 7522
Gm,that front yesterday reenergized over eastern new england last night,hvy wind swept rain,thunder,lots of trees down around our area.Just goes to show you,add some upper support and stir things up
Member Since: September 6, 2007 Posts: 878 Comments: 15739
Buffalo had some flooding from the Low over the NE. For us none snow lovers, we have to be thankful it wasn't 15 degrees colder.
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Cornell University- Atmospheric Sciences Undergrad; Research Assist.- Onset of Spring Indices Toolbox; Interests- Small spatial scale climatolology

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