Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 4:56 PM GMT on February 16, 2009
"Afternoon Thoughts" (Updated 2/16)
Good afternoon! Wow, 16days since I posted a blog, my apologies. It was nice to take a bit of a break from blogging, but I am now ready for more interesting weather.
There has been a lot of talk from everyone including myself about the end of winter. Really, though, it seems premature to say that as the calendar only shows it being mid February. Yes, by this time the sun does make it difficult for daytime road snow accumulations and difficult to hold a snow pack, but some of our biggest snows have been held in the next few weeks. Just think that six years ago on this President's day we were sitting in glory at one of the largest snowstorms to hit this region. Yes it was only six years ago, which is not really that far off. I think we are all a bit irritated by the disappointment of long term forecasts to the point where I do not even mention any storm predictions until several days before the event. This winter has proved senseless in forecasting long term. Then you have to wonder why the models did not show great lakes cutters only to be changed a few days before the event to a nor'easter. But overall as I have been continuing to mention, the pattern has not been supportive of coastal storms. And yes we go another year without a true Miller A storm and a true Miller B storm. The pattern has been progressive and transient which we call all thank La Nina. Forecasts for this winter we of snowier conditions than last year, but really we are about the same. The La Nina took everyone by surprise including the NCEP. This winter's forecast of colder than normal conditions definitely panned out though considering the brutal January we had and below normal November and December. But I will leave winter forecast verifications for another time. To get the snowy winter we desire, we have to get rid of La Nina and get rid of the decadal negative PDO. Until then, we will not see snowy conditions return. Current predictions bring Nino conditions in a few months, so I guess we will see. For those still wishing for a major, historic winter storm; they will be hard to come by through the rest of winter. Conditions would have to be perfect in this type of pattern, and we have had anything but a lucky winter. In any case I would bet on some more snow before the winter's end, and it is definitely too premature to end winter now. Mid March, yes but mid February, definitely not. Have a wonderful day!
"Current Surface Plot"
(Courtesy of HPC)
(Courtesy of Wunderground)
(Courtesy of NOAA)
"Forecast Discussion" (Updated 2/16)
A weak shortwave passing to our south with best forcing remaining to our south will result in cloudy conditions over the mountains and light snow showers. Decent dendritic growth and colder surface and upper air temperatures will support higher snow ratios near 15:1 giving way to light accumulations C-2inches especially over the northern Laurel Highlands in northern Somerset and Cambria Counties. A 1028mb high pressure will move across the region later Monday eroding western snow showers and strato-cumulus clouds. Clear skies will prevail Monday night under ideal radiational cooling conditions. Tuesday will feature clear skies and near normal temperatures under the high pressure regime before high cirrus clouds funnel in across western and westcentral Pennsylvania later in the day. Clouds will lower and expand Tuesday night as the next storm system approaches from the region. A 996mb low pressure will go roaring up through the Great Lakes with limited moisture available along with lacking decent frontogenisis. H85s rise above 0C across most areas south of Turnpike nearly immediately as precipitation moves into region. Mid level H8 will also feature a warm nose for areas around and just north turnpike giving way to more sleet than snow. Any sleet/snow accumulation will be light to none south of I-80. Some better mid level forcing and colder air will give areas across northern Pennsylvania generally 1-2inches with possibly 4inches for areas especially in northeastern portions of the state and the higher elevations. After the upper level southeasterly winds with rising temperatures, boundary layer temperatures will shortly rise limiting the freezing rain threat. Clouds will inhibit temperatures from falling too much Tuesday night. Best chance of ice accretions will be across northern Pennsylvania with up to .2inches of ice. Elsewhere accretions will be up to and less than .1inch. Cold front passes through region later Wednesday night with rapidly falling H85s. Precipitation amounts with first system will generally be .25inches for most areas with some areas with QPF near .5inches especially across northeastern regions. A dry slot may even move in for eastern areas. As a colder northwest flow rushes into region for Thursday a weak broad shortwave will move into the region giving way to widespread orographic snows. Snow accumulations will be advisory criteria for western and some central areas with accumulations 2-5inches. Areas east of mountains will generally see a trace to up to an inch and a half. Northwest flow keeps most western terminals at MVFR or IFR conditions for Thursday and part of Friday. Another trough moves in for the weekend with a potential Alberta Clipper dropping down from Canada. Some model guidance suggests moderate QPF events for the clipper, but at this point that idea looks suspicious.
(Courtesy of Penn State Meteo.)
"Current Water Vapor Loop"
(Courtesy of Penn State Meteo.)
"Weekly Forecasts" (Updated 2/16)
Monday- High pressure generally dominates the region except for a weak wave moving to our south. Low stratus clouds will prevail over the Alleghenies and Laurels throughout the day with lake effect snow showers. Higher snow ratios even with poor forcing should result in light accumulations on favored ridges with nearly 1-3inches in some areas. Winds will generally be light today out of the north-northwest near 5mph. Highs will remain on the cool side with temperatures just slightly below normal ranging from the upper 20s over the mountains to the upper 30s in the south and eastern portions of the state. High pressure moves into the region for Monday night giving way to clearing skies and calm winds. Radiational cooling will give way to cold low temperatures in the teens for most locations to single digits for a few sheltered and colder valleys in Tioga and Potter Counties.
Tuesday- High pressure remains in control for generally a nice day. Temperatures will be a few degrees on either side of normal values with highs in the 40s for eastern areas and low 30s for the mountains. Skies will be sunny with only a few low clouds over the higher elevations in Cambria and northern Somerset County. A cirrus deck will move in across the region later in the day Tuesday especially across western areas. Warm air advection will expand and lower the cloud deck as evening approaches. Tuesday night will feature lows warming across western areas and steady lows for central areas with cooling lows for eastern areas. Cloud deck will inhibit any significant radiational cooling for most locales. Light snow will break out across the west quickly changing to sleet followed by plain rain within an hour or so. A coating of snow is possible across the Laurel Highlands as colder air will hang tough. Lows will be around 32degrees in western Pennsylvania with mid to upper 20s elsewhere.
Wednesday- A low stratus deck dominates the region for most of the day as a low pressure heads up northwest of Pennsylvania. Warm air advection will promote some snow generally north of I-80 with accumulations 1-4inches. South of I-80 snow accumulations will be anywhere from a trace to up to one inch. Surface temperatures will warm up enough for most areas to turn to plain rain by afternoon. Some freezing rain is possible in favored mountain slope locations with accretions up to .1inch for most areas. Dense fog will be across north central Pennsylvania where deep snow pack remains. Rainfall amounts will generally be light as dry slotting should cut down on totals. Rainfall amounts will be up to .25inches for most areas. High temperatures will be in the 30s for most areas in the mountains and to the east. 40s will be prevalent for western Pennsylvania. Wednesday night will feature plain rain for all locations with light amounts. A cold front advancing in from the west will slowly change over some locations to light snow across the west. Tight pressure gradient may bring some gusty winds by day break also. Low temperatures will generally be in the 30s for most locations.
Thursday- A wave approaches from the west along with slowly dropping temperatures for Thursday. Widespread snow shower activity will be across the western half of Pennsylvania with more intermittent snow shower activity for eastern areas. Snow accumulations will be in the 2-5inch range for favored mountains and 1-3inches for valley locations. East of the mountains snow accumulations will range from only a Trace to up to 2inches. Little if any snow accumulation will be southeast of the Allentown-Reading-Coatesville line. Winds may also be a bit gusty under the northwest flow with occasional gusts up to 35mph for some locations. It may approach wind advisory criteria for the higher elevations. Blowing snow will cause poor travel conditions at times during the day Thursday. Highs will be falling but generally in the upper 20s and 30s for the western half of the state and in the upper 30s to low 40s for eastern areas. Thursday night will feature more snow showers will accumulations more widespread as sun sets. An additional C-2inches is possible in many locations. Winds will continue to be breezy and occasional gusty. Lows will be cold in the teens and 20s for many areas. Clouds will be prevalent across the state.
Friday- Snow showers will be ongoing for areas in the mountains and favored northwest regime areas during the first half of Friday with very light additional snow accumulations generally less than one inch. Downsloping winds will give way to partly cloudy skies for other locations. Temperatures for highs will be below normal with mid to upper 30s for eastern areas and low to mid 20s for the mountains. Winds will begin to be a bit more calm. Frozen lake Erie will inhibit widespread lake effect snow. Friday night will feature partly cloudy skies statewide as a potential clipper moves into the region. Lows will be in the 20s statewide.
"Current River Ice Reports and Ski Conditions" (Updated 2/16)
Much of the once expansive river and lake has melted thanks to the early February warm spell and extended winter heat wave. But there are still many smaller ponds that had nearly 12inch thick ice, with ice still remaining. Any ice on any ponds/lakes/rivers is very unsafe and no one should be walking on it. There ice is very thin in spots that can not be visible to the naked eye. For the coming week any ice activity should be canceled and taken with caution for northern mountain areas. Ski conditions remain decent statewide courtesy of the snowy and cold January that aided in the best conditions in years. Some fresh snow has coated most areas with C-2inches from Saturday night especially around the turnpike. Additional snow accumulations do look likely this week. The Laurel Highlands should expect an additional 1inch of snow Monday. Another 1-2inches of snow early Wednesday. Snow accumulations in the Thursday to Friday time frame will be advisory criteria with total 3-6inches for most slopes. For the Poconos, 1-4inches is possible early Wednesday. An additional 1-4inches is possible Thursday and early Friday. Across southern slopes in the southcentral mountains and Lehigh Valley hills accumulations will be spotty this week with up to 2inches in isolated locations Thursday. A coating of snow is also possible early Wednesday. Snow making conditions will return for the weekend for all locations with a possible clipper type system for next weekend possibly affecting all of the slopes with new snow.
-Link to official reports page from NWS...Link.
-Link to local ski resort snow conditions...Link.
"Current Northeast Snow Depth and Northeast Windchills"
(Courtesy of Wunderground)
"Lake Effect Snow Conditions" (Updated 2/16)
With Lake Erie generally frozen over, it will inhibit any significant lake effect snow outbreaks. But this week will feature some lake effect and orographic snow activity. Monday will feature a shortwave passing to the south of Pennsylvania. But under the northwest flow and slightly added moisture will give way to some snow showers for the Laurel Highlands and central Mountains. Snow accumulations will be light and limited to generally grassy surfaces with them ranging from C-2inches. Mt. Davis and Laurel Summit will see slightly higher totals up to 3inches. Under the 310 trajectory flow, northern facing slopes will do best in this setup also. High pressure remains in control for Tuesday. A synoptic event will occur Tuesday night through Wednesday night. Then a more cyclonic flow will occur for Thursday and could be quite significant for some mountain locations. An enhancing shortwave and gusty 300 trajectory flow will favor widespread lake effect snow shower activity. High Omega values and decent dendritic growth will favor snow ratios near 20:1 for some of the higher elevations above 2000ft. Snow may at times be heavy for parts of the Laurel Highlands during the day Thursday limiting visibility and conditions to IFR for KJST, KBFD, KAOO, KFIG, KERI, and KPIT. Snow accumulations for the valleys will be 1-4inches. Snow activity will be lake effect completely driven by Thursday night and Friday with additional 1-3inches of snow for typical upslope locations including parts of northeastern Pennsylvania in Bradford and Wayne Counties. Weak ridging moves in for late Friday ahead of the next trough with potential lake effect snow behind that for Sunday and Monday with light accumulations.
"Current Lake Erie Wind Direction and Speed"
(Courtesy of NOAA)
"Current Lake Erie Water Temperature"
(Courtesy of NOAA)
"Long Term Outlook" (Updated 2/16)
I will quickly mention the possibility of a clipper for next weekend. Latest guidance suggests it dropped down from Canada with even the GFS showing a hybrid Miller B scenario for a coastal storm. EURO hinted at this a few model runs ago also. But take it with a grain of salt at this point. For now it is just another thing to monitor this week. As far as the long term pattern goes, it looks relatively normal with seasonal cold air and chances of storms. Nothing really strong enough to indicate extreme warmth or extreme cold. Sometimes in these seasonal patterns some areas can see some decent snows. MJO looks a bit more favorable by late Month in phase 7 and 8. NAO looks neutral and with a negative PNA. Lack of any blocking and the progressive flow should inhibit any significant east coast storm from forming. The EURO is a bit warmer than the GFS in late month with slightly deep western trough. Overall long pattern really could go either way, so no reason to give up hope on snowless storms. Pattern looks fairly like last February Nina like, and we picked up snow in that type of pattern making up for earlier in the winter.
"Current NAO and PNA Predictions"
(Courtesy of NOAA)
"Monthly Outlook" (February)
Well January finishes on quite a cold note continuing the trend for my winter outlook of below normal temperatures. I am very pleased with my forecast for January of below normal temperatures and normal snowfall. All climate reporting locations in Pennsylvania have reported a below normal mean generally in the (-2)-(-5). Snowfall for the month came in below normal for southern and eastern areas thanks to some mixing. But other than Philadelphia anomalies for snowfall were not really too far off typical means. Lake effect snow belts reported above normal snowfall for January along with northern Pennsylvania which saw well above normal snowfall. Overall January went relatively according to plan. February's forecast does not look quite so easy to forecast. February is the last month for my winter forecast that consisted of December, January, and February and the month looked to be volatile in terms of pattern. Looking at teleconnections the CPC NAO index does report a negative reading for the first half of the month. But looking at heights up towards Iceland it seems that this will be an east based negative NAO which does not really help winter storms for the eastern CONUS. When the models were progging our inland superstorm the low bombed out to near 950mb across northern Canada and changing the overall pattern. Large systems like that generally are pattern changers. So when this 950mb low headed north it shifted the negative NAO to a more favorable west based negative NAO. This no longer seems to be the case. Looking at the PNA it is headed negative giving way to an unfavorable negative state making the Pacific a thorn in our side to try to get any winter storms. The only positive thing I can find in the teleconnections is the highly negative AO progged by mid month. But with a lack of cold air across the northern Hemisphere this may be difficult to occur. The MJO looks to be in unfavorable phases during this month for eastern troughing. It also appears again we have an active northern jet stream which will favor southwest flow events, overrunning systems. This leads me to believe a lower confidence than normal monthly outlook.
Temperature- I am going to take a risk and go against what has been the case this entire winter. I am forecasting normal to above normal temperatures. Above normal temperatures should range from (+2)-(+4). Areas at most risk for above normal temperatures will be south of I-80 as a weak trough may hang up over New England keeping those areas cooler including northern Pennsylvania. The first half of the month definitely looks to be more mild than towards mid month when potentially colder air works in.
Precipitation- Precipitation wise I am going with normal precipitation with normal to below normal snowfall. The northern jet should be active, but with lacking surface features and teleconnections it should be harder to get all snow events. This does not mean a large snowstorm is not possible because towards the 10-12 there have been some indications of potentially a snowstorm. Also with the lakes just above frozen over, this will limit lake effect snow. In any case February is typically the snowiest month for Pennsylvania, so I guess we will see what happens this month.
"Temperature and Precipitation Outlooks from Climate Prediction Center for next 30 days"
(Courtesy of NOAA)
-Winter 2008-2009 forecast... Link.
-Winter 2008-2009 forecast update... Link.
"Here northeast of Harrisburg 2008-2009 winter statistics"
Current Snow Cover- Trace
Monthly Total- 3.85inches
Seasonal Total- 22.40inches
Winter Weather Advisories- 6
Winter Storm Warnings- 2
Ice Storm Warnings- 1
Blizzard Warnings- 0
Freezing Rain Advisories- 0
Winter Storm Watches- 4
Lowest High Temperature- 14degrees
Lowest Low Temperature- -3degrees
Wind Chill Advisories- 0
Wind Chill Warnings- 0
(Snow Storms Stats)
First Snow - October 29 - Trace
First Snow on Ground - November 18 - Coating
Lake Effect Snow - November 21/22 - 6.00inches
Synoptic Snow - December 16 - 3.50inches
Clipper - January 17-19 - 1.50inches
Synoptic Snow - January 27/28 - 4.00inches
Lake Effect Snow - 2.00inches
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