Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 2:16 AM GMT on November 27, 2009
"Afternoon Thoughts" (Updated 11/26)
Good evening and happy Thanksgiving to all!!! This blog covers the daily forecast from Friday through Monday. Keep in mind being Thanksgiving I did not have quite enough to time to put together a real detailed blog, but this is a basis for the coming days. Another weekly weather blog will be issued on Monday for forecasts from Monday through Friday. It looks like finally there will be some interesting weather to talk about. Anyways it is hard to believe Thanksgiving is already over and Christmas is right around the corner. But first we have Pennsylvania's unofficial holiday, First day of deer season, lol. It looks like it will not be too chilly for the opening day with only a bit of residual snow on the north sides of mountains especially in the Laurels. December is my favorite time of year, as I just believe the holidays brings everyone together and is a time for celebration. Looks like this weekend will be my annual decorating weekend as I fight the 100 white twinkling lights dying with me throwing out about half of the strands. Ugh, every year it is a mess. This year I think I am going to invest in some of those LED strands of lights and these regular light white lights cause so many problems. Looks like many of local community tree lightings will be occuring in the coming weeks with plenty of community activities. Despite living in a typical residential neighborhood along Blue Mountain, I like to think of myself in one of those New England small towns where every knows everyone. A sense of community is always something I take pride in and I believe is very important. Small towns have always been my calling, with cities being my enemy. I would much rather live up in the mountains than ever being in a city apartment, but for some people that is their calling. I think that is what all makes us unique. We have a lot to be thankful for living in the United States despite us always complaining. I have been to several other counties and nothing compares to the hospitality and infrastructure of the United States. While we tend to be thankful for on Thanksgiving for our family, it is also time to reflect on our troops and wonderful country we live despite our daily complaints. Have a wonderful day!!!
"Current Surface Plot"
(Courtesy of HPC)
(Courtesy of Wunderground)
(Courtesy of NOAA)
"Forecast Discussion"(Pennsylvania, Maryland, Delaware)(Updated 11/26)
Well it is soon that time of year where every forecast becomes a challenge. While that may be a frustration, it also brings a challenge to the table which I find fascinating. Anyways this discussion will be through Monday of next week. A marginal pattern changing cold front is marching across the Ohio Valley this Thursday evening and will continue to move across the northern Middle Atlantic. MOS suggests temperatures will fall nearly 5-10F behind the front with dewpoints depressions nearly similar drops generally near freezing wet bulb temperatures or slightly below especially for the western half of the state. Meanwhile as this front moves east, a strengthening Miller A low pressure will continue to strengthen up the coast. As pressure drops near -3mb/3hr bombogenesis will occur towards New England. With near (-10)-(-14)F falling temperature in the last 24hrs, this will suggest colder air to possible catch up with some of the moisture over western Maryland and parts of Pennsylvania. This will pose the threat for lake effect snow and orographic snow. See details in lake effect section below. As this cyclone continues to strengthen to at or below 985mb, a tight pressure gradient will develop on the west side of storm creating a 305degree northwest flow causing gusty winds aloft and at the surface. Winds will increase to near 40-50knots in the 0-6km range allowing for 30-45mph winds to mix down to the surface during the day Friday across the entire northern Middle Atlantic. Elevations above 2500ft will have the highest threat for winds to approach advisory criteria. Interesting conflictions develop Friday morning. SREF guidance and the high resolution NAM suggest some weak deformation precipitation acrosss northeastern Pennsylvania. With some weak frontogenesis and added orographic lift, this .1-.25inch precipitation deformation seems probable especially from the Susquehanna Valley up through the northeastern mountains. Current radar trends already suggest this band of precipitation towards central Pennsylania. Cold air advection with H85 temperatures below -4C may allow for some snowflakes to mix as there is some elevated 50 j/kg CAPE over the lower to upper Susquehanna Valley. Any briefly heavy precipitation could pull down some sleet, graupel, or snow. Temperatures aloft look well below freezing with 1000-500mb heights near 534dm, but surface temperatures are marginal. In these situations 925mb temperatures are a good tell tale sign for boundary layer temperatures as GFS 2m temperatures are highly inaccurate. Anyways in this instance 925mb temperatures remain around 0C. So again a possible light coating of snow is possible towards the higher elevations of northeastern Pennsylvania back through the upper and middle Susquehanna Valley. Elevations above 1300ft have the best chance to see a coating. Towards the Laurel Highlands and western Alleghany Plateau lake effect snow will be ongoing with the 305degree northwest flow. Accumulations of up to 5inches are possible along the highest ridges in Cambria and Somerset Counties. 11/26 12z NAM indicates low pressure will pull towards the Gulf of Maine quickly by Friday night with a more downsloping flow ending most of the northern Middle Atlantic precipitation except for Garret County, Maryland up through the Laurel Highlands with additional accumulations only around a C-1inch. It will continue to be breezy through Saturday as the northwest flow remains tight over the region with a -1D trough allowing for slightly below normal temperatures. GFS guidance appears to be running too cold, so my forecast below added for some sunshine to allow temperatures to rise a bit more than MOS guidance. A typical northwest flow will occur through Saturday with strato-cumulus especially towards the mountains with sunshine east of the Blue Ridge. Cold front stalls off the east coast and will be a catalyst for a weak overrunning precipitation event towards Monday night and Tuesday of next week. Sunday weather looks pleasant with sunshine over the entire region and near normal temperatures. As the front washes out off the coast, another weak front will approach the region allowing the flow aloft to turn slightly to the southwest allowing for H85s to rise near 0C or slightly above. Cirrus will overspread the region Monday with near normal temperatures with precipitation approaching the region overnight late. Temperatures again are marginal so rain is a higher probability than mixed precipitation. But there has been an evident southeast and colder trend especially in the GFS and ECMWF guidance, so stay tuned!
(Courtesy of Penn State Meteo.)
"Current Water Vapor Loop"
(Courtesy of Penn State Meteo.)
"7-Day Zonal Forecast Outlooks"(Pennsylvania, Maryland, and Delaware)(Updated 11/26)
Friday- Friday will feature the coolest weather of the upcoming days as a trough axis centers over the region with a strengthening low pressure passing near the 40/70 benchmark slightly to the east causing a norlun trough to form allowing for some morning rain/snow over eastern Pennsylvania particularily the higher elevations. Any convection may allow for some graupel, sleet, or wet snow flakes. Meanwhile northwest winds will allow for lake effect snow to occur in the typical belts with accumulation ranging from 1-5inches depending on elevations. Somerset County south through Frostburg and into Garret County Maryland have the highest chances at seeing the most snow. Temperatures will range from near freezing above 2000ft to upper 30s over the valleys of western Maryland and western and northern Pennsylvania. Most other areas will be steady in the 40s with only a slight chance at a rain or brief snow shower. Rainfall QPF should generally be less than .25inches of eastern Pennsylvania. Friday night will allow for the relaxing of the very gusty winds up to 45mph and will bring an end to the widespread lake effect snow with additional amounts around C-1inch. Lows will range from the 30s over central Maryland and Delaware up through southern Pennsylania to 20s over the higher elevations of Maryland and Pennsylvania.
Satuday-Monday- It appears a very calm few days of weather are likely Saturday through Monday with similar conditions. On Saturday winds will be relaxing, but the northwest flow will remain with highs ranging from the upper 40s to upper 30s over the region. Lows will be in the 20s to mid 30s towards Washington DC. Similar conditions will occur Sunday and Monday, but there will be slightly more sunshine with temperatures nudging 50 over Maryland, Delaware, and southern Pennsylvania. A storm system approaches the region towards Monday night with increasing clouds.
"Current River Ice Reports and Ski Conditions" (Updated 11/26)
Very poor conditions for snow making currently exist across the northern Middle Atlantic with Blue Knob being the only ski resort open with just tubing available. But we are approaching the dates of a few openings towards the Poconos for the start of next week. With the first widespread lake effect snow event of the year, some of the ski resorts in western Pennsylvania will get a bit of fresh snow with Blue Knob likely picking up 1-3inches of snow on Friday. The Laurel Highlands western facing ridgetops may see up to 4-5inches of fresh wet snow by Saturday late morning. Towards Deep Creek, Maryland in Garret County ski resorts will likely see a fresh 2-4inches of snow, which will help in the snow making process. It appears openings for ski resorts will be delayed this year especially after last year's early start. This mild November has prevented pretty much any snow-making over the entire Northern Middle Atlantic and even up through New England. But finally it appears climatological norms will be over the region for the next two week with several opportunities for snowfall. Nothing looks overally spectacular as the Atlantic will not be cooperating, but a favorable Pacific can deliver widespread snows even without Atlantic upstream blocking. As far as river ice reports, obviously there is no ice on local waterways. A few shallow ponds may develop sheet ice over the western and northern Mountains especially in northern facing valleys above 1800ft, but ice definitely remains to thin to even attempt to step on. Seek caution while near local waterways as water temperatures continue to fall. Towards Lake Erie the water temperatures continue to fall through the 40s and will continue to fall in the upcoming months. For information on a few opening dates for ski resorts in Pennsylvania, see the list below...
Blue Knob... Tubing Open.
Blue Mountain Ski Area... December 1
Camelback Ski Area... December 5
Ski Big Bear... December 12
Tanglwood Ski Area... December 18
Eagle Rock... December 19
Mystic Mountain... December 24
-Link to official reports page from NWS...Link.
-Link to local ski resort snow conditions...Link.
"Current Northeast Snow Depth and Northeast Wind chills"
(Courtesy of Wunderground)
"Lake Effect Snow Conditions" (Updated 11/26)
GFS bufkit profiles indicate a veerying wind profile and decent Omega growth over western and northern Pennsylvania through western Maryland, which will provide for a minor to moderate lake effect snow outbreak. As bombogenesis occurs with the 985mb low which will move towards the Gulf of Maine, this will allow for a tightning pressure gradient with -3mb/3hr pressure falls causing northwest winds gusting near 30-40mph with 45mph gusts over elevations of 2000ft. Orographic lift combined with moist RH values 700mb aloft, this will allow for a relatively widespread event, but lack of forcing and cold air will keep accumulations relatively marginal. Snow will develop widespread over western Maryland overnight Friday especially towards early Saturday morning. Critical thickness indicate 1000-500mb heights near 535dm over the region with -6C H85 temperatures. But boundary layer temperatures remain marginal even aloft, so accumulation will be hard to come by especially with how warm it has been in the last two to three weeks. Several periods of moderate snow are possible from Garret County, Maryland up through Bradford, Pennsylvania with accumulations generally around 1-2inches for the lower elevations in the Laurel Highlands and northwest mountains with up to 4-5inches on the ridgetops especially towards Mt. Davis and Laurel Summit. Wind profiles will allow for a 305degree flow shifting to around 318degrees towards Friday evening. Drier air will move in aloft towards Saturday morning cutting off the lake effect snow machine. Areas towards Pittsburgh may see on and off periods of light snow, but accumulation will be minimal. The best chance of the higher accumulations will be in northern Garret County up through southern Somerset County. Activity will generally be a widespread stratiform upslope event lacking streamer organization. Activity will become more intermittent and cellular towards late Friday afternoon. Any snowfall will have a large impact on travel plans for those coming home from Thanksgiving. Holiday shoppers will also be impacted so please seek caution while driving through parts of Pennsylvania and Maryland on Friday even on the Pennsylvania turnpike. No additional lake effect snow is expected through at least Monday.
Snow Map November 27...
*Note valleys will see lower side of accumulations while higher elevations do exponentially better with the higher end of totals.
"Current Lake Erie Wind Direction and Speed"
(Courtesy of NOAA)
"Current Lake Erie Water Temperature"
(Courtesy of NOAA)
"Long Term Outlook" (Updated 11/26)
I remain at odds with the long term outlook and sort of remaining distant from global model predictions for a few select reasons. Yes the GFS looks fantastic in the long term with snow chances and generally very cold temperatures starting around the 5th of the month. And yes the ECMWF remains similar with an impressive trough over the region towards the day 10 map. My concerns are these... The MJO is beginning to show some signs of weaker convection over the Indian Ocean with weak forcing. Some HIRES GFS ensembles indicate little to no forcing from the MJO, while some guidance suggests it moving into the favorable phases of 6-8. If we see little forcing of the MJO, a general zonal flow will exist over North America with Pacific Airmasses. One thing I agree with guidance is the idea of a favorable Pacific. We will be developing a strong Aleutian Low with a ridge over central Alaska maintaining a positive PNA and negative EPO. But towards the Atlantic there are problems. Basically we have an incognito NAO whichs looks negative, but in reality is very east based which will cause the coldest of air and favorable upstream blocking for western Europe, so for now ignore the CPC charts for the NAO. Also we continue to lack a good position for the polar vortex as it continues to allow the coldest of air over Siberia where record snow pack is occuring. Towards Canada snow pack remains well below normal, but as we know that can quickly change. Still though with record low levels near the Hudson Bay, that cannot have good snow implimations for the United States. I continue with my thoughts of a "step down" pattern, which is one that takes an extended period of time for the cold air to reach the northern portions of the United States. I expect the northern Middle Atlantic to average near normal for temperatures for the next one to two weeks. Current GFS does impliment a coastal storm towards December 5, but it appears extropolation of reality of the 500mb pattern would cause the trough axis to be farther west allowing for an Ohio Valley storm. Still though time to monitor. But I things will be favorable towards the 8-11th of December for a significant chance at a winter storm over the region. That period looks favorable wavelengh wise and even the latest GFS and ECWMF show possible coastal implications over the east coast in this time frame. In any case the pattern does look much better than the past two weeks, but for now I am not buying the wintry look the GFS has for the long term. First widespread snows in my opinion do not look to far off, probably in the December 1-10 time frame. But I do think after that winter storm chance around the 8th or 11th, we see serious cold headed towards North America as the polar vortex relocates. My December forecast will be issued this coming Monday!!!
"Current NAO and PNA Predictions"
(Courtesy of NOAA)
"Anchorage, Alaska Tower Cam"
*Note I am only posting this towercam until snow starts falling over the northern Middle Atlantic, lol. For now we can all be jealous of the Alaskan snow.
"Monthly Outlook" (November)
Well, how quick time flies by as now it is time for me to express the November Outlook. October went by pretty according to forecast with most climate reporting stations in my forecast (-1)-(-2)departure zone for areas excluding Philadelphia on southward which saw near normal temperatures. Many areas had their coldest October on record in the running around midmonth as a strong nor'easter brought snow to north central Pennsylvania with very cold temperatures, but later in the month temperatures warmed up with a sudden swing in the pattern to bring very mild temperatures for the last week of the month. Precipitation though was a bit more than forecast, with forecast calling for normal precipitation, but it turned out many areas are nearly 1-2inches above for October. But the change from the dry period to the active period was nailed by the original forecast, which called for the switch around midmonth which was accompanied by the series of nor'easters. All in all October's forecast was very successful. Anyways onto the November forecast. This was a difficult forecast for me as a lot of teleconnections and guidance show conflicting equations for a final solution. Teleconnections appear to support a near seasonal pattern for the first half of the month, before guidance starts to diverge in solutions. Latest ECMWF weeklies support a switch to a colder regime around the 10-15th of the month; this is also backed up by some of the ridiculous arctic runs of the GFS. The October 31, 12UTC ECMWF model suggests towards the 11th of November a return of the Aleutian Low with a weakly negative NAO forming, negative EPO, and a weakly positive PNA. This all suggests a possible pattern change to the trough axis surging eastward towards the east coast. Meanwhile Nino region 3.4 SST anomalies continue to rise favoring the moderate El Nino, which goes according to forecast. So all of this leaves a difficult forecast…
Temperature- It appears we will start the month with near normal to slightly below normal temperatures for the first week as we manage a weak trough in control with a series of high pressures. This will result in near normal highs, but well below normal low temperatures with ideal radiational cooling. Most locations will drop below freezing several times for this first week of the month. Towards the second week of the month and third week of the month is where model guidance is suggesting a negative AO, which will allow cold Canadian air to enter the continental United States. According to guidance this could be over the east coast with possible well below normal period. But as in El Nino regimes, patterns are transient even during the height of the winter so I do not think a trough dominates the flow of the east coast the entire month. There should be periods of above normal days between troughs entering the Midwest parading on eastward. Not exactly set in a forecast for Thanksgiving week, last week in the month, but the ECMWF weeklies are predicting temperatures to be below normal. Therefore my temperature forecast is going to be as followed... A general (-1)-(-3) departure for monthly anomalies for much of Pennsylvania and western Maryland, excluding Philadelphia. Towards the rest of Maryland through extreme southeastern Pennsylvania and all of Delaware I am going with a (+.5)-(-.5) temperature anomaly for the month. I think a weakening southeast ridge along with easterly flow for the first week will prevent ideal radiational cooling therefore limiting the below normal temperature extent in this region.
Precipitation- Precipitation proves difficult as usual because other than existing patterns, there is not too much information to base a forecast off of. I am going to go with a near normal precipitation month, but there is the possibility that the month could be dry. With nearly the last 6 months being above normal precipitation months, I will stick with a continued semi wet pattern. The first week of the month looks dry with perhaps a stormier pattern towards the middle and end of the month. If the center of the trough axis remains near the east coast, then likely the pattern will by drier. So a good rule of thumb for one to follow this month is a colder month will likely be drier and a warmer month will likely be wetter. Troughs situated to our west allow for warmer temperatures with weak ridging, but also active storms moving up through the Ohio Valley. As for snowfall, that forecast is extremely difficult but I would not be surprised if most all areas see their first flurries this month in the entire Middle Atlantic with a few periods of lake effect snow accumulation especially if the GFS cold outbreak pans out. As for synoptic snows, that remains to be seen.
"Temperature and Precipitation Outlooks from Climate Prediction Center for next 30 days"
(Courtesy of NOAA)
-Winter Outlook 2009-2010...Link
"Here northeast of Harrisburg 2009-2010 winter statistics"
Current Snow Cover- 0inches
Monthly Total- 0inches
Seasonal Total- 0inches
Winter Weather Advisories- 0
Winter Storm Warnings- 0
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 0
Winter Storm Watches- 0
Lowest High Temperature- 41degrees
Lowest Low Temperature- 23.5degrees
Wind Chill Advisories- 0
Wind Chill Warnings- 0
(Snow Storms Stats)
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.
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