Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 3:26 AM GMT on February 21, 2009
Ah, it is that time of year. Being nearly 3/4ths through the astronomical winter and only 7 days till the end of the meteorological winter, it is time to take a look back at some of the interesting weather events of the 2008-2009 winter. This winter has been marked by colder than normal temperatures and below normal snowfall. Last year I also posted a winter recap about half way through the winter, see link below. In each storm summary, the link provides back to my blog from the storm.
Look back at a typical Pennsylvania's winters...
An average winter in Pennsylvania consists of many different types of winter weather. Winters in Pennsylvania are more severe than middle Atlantic winters and Ohio valley winters, but less severe than neighboring New England winters. On average the first snowflakes fall in mid to late October in the northwestern part of the state. And the last snowflakes typically fall in the northwestern part of the state in early May. Frost season lasts from early October to mid May in most areas. The geographic regions of Pennsylvania play a major part in snow totals and temperatures.
("Courtesy of NOAA")
There are two regions of Pennsylvania that see significantly higher snow totals than the rest of the state. The Laurel Highlands and Northwest Mountains see snow totals well over 100inches every winter. In extreme winters snow may be on the ground into June with seasonal totals of over 200inches. The seasonal snow total record is held in Corry, Pennsylvania of 237inches. The monthly snow total record is held in Blue Knob, Pennsylvania with 96inches of snow. Corry is found in the northwest mountains and Blue Knob is a ski resort found in the Laurel Highlands. Blue Knob is the highest ski able mountain in Pennsylvania. Below is a map of average seasonal snow totals in Pennsylvania.
("Courtesy of NOAA")
Different types of winter storms affect the state of Pennsylvania, clipper systems, lake effect snow outbreaks, nor'easters, advection snows, and etc. The coldest month is typically January statewide. And the snowiest month statewide is typically February. Northwest Pennsylvania typically sees a majority of their snows in Lake Effect snow outbreaks. While eastern Pennsylvania sees most of their snows from coastal storms. When coastal storms come up the coast many areas in Pennsylvania can see major snowstorms. The Poconos typically see the most snow from coastal storms due to their elevation aid to precipitation totals. Some of the greatest storm total snowfall records are actually held in eastern Pennsylvania and not in the northwest Snowbelt regions. The highest average seasonal snow average is found in Corry, Pennsylvania with an average of 118inches. While the low seasonal snow total is found in Philadelphia, Pennsylvania with 21inches of snow. As far as temperatures go the coldest temperatures are found in the Alleghany Plateau region with the lowest temperature every recorded in Pennsylvania was in Smethport with -42degrees. Temperatures typically dip below freezing every day from November to March statewide. Extreme cold outbreaks typically occur around mid to late January. At times warm thaws may occur, but they are rare and sparse. As for ice storms they typically occur in December when the sun's rays are at their lowest. Very odd winter weather features occur each year including thunder snows, etc. and thunder snows are like thunderstorms but with snow instead of rain. Snow rates up to 5inches can occur. Thunder snows are mostly likely associated with frontal passages and lake effect snows. As far as winds, typically northwest winds setup on the coldest of winter days and can gust up to 50mph. Wind chills as low as -25degrees are felt almost at least once in the mountains of Pennsylvania. On average winds gust to 30mph several times each month. For ice on waterways, many northern lakes and rivers solidly freeze every winter. For southern areas ice forms every winter, but does not necessarily become very thick. During extreme winters though even southern regions can see ice thicknesses of over a foot. The most extreme winter storms that affect Pennsylvania are nor'easters though. They affect large areas of the state with high winds and heavy precipitation. On rare occasions snow totals of over 35inches have occurred with snowdrifts as high as 6ft in many areas of eastern Pennsylvania. Winters in Pennsylvania overall are relatively severe, with geographic regions playing a major part in average snow totals and cold temperatures.
October 28-29 Halloween Wet Snow...Link.
It is hard we to believe we have to go all the way back to October. But winter started early and kept on through the end of January with solid cold air. An interesting weather setup occurred with relatively short notice for forecasters as latest guidance suggested a low pressure forming along a quasi-stationary boundary and track nearly up the eastern Hudson Valley. The low bottomed out at 988mb just north of Long Island and it cruised northward. H85 temperatures crashed along the backside of the low pressure as it strengthened and evaporational cooling allowed the higher elevations to see some snowfall. The precipitation shield was generally confined to eastern Pennsylvania as 850s fell below 0. Winds aloft near 60knots brought down some 55mph gusts on the west side of the low pressure creating blizzard conditions where snow was falling. As the low pressure lifted northward a deformation band formed with nearly 40dbz mesoscale bands across the far northeast. Snow rates were near 1-2inches per hour. Due to the early nature of the system snow ratios were only near 10:1 resulting in a very wet snow causing long lasting power outages and tree damage combined with high winds.
Figure 1.1 shows the low pressure system just east of New York City on Long Island at 18z October 28 at 992mb.
A heavy elevation specific snowstorm occurred with extreme and near record breaking snow totals for parts of the northeastern state of Pennsylvania. Highest amounts were recorded across Lackawanna County, Luzerne County, Wayne County, Pike County, Carbon County, and Monroe County.
Figure 1.2 shows our own Stan999's picture during the height of the storm with a recorded 17inches.
Dynamic cooling under the rapid deepening of the low also resulted in some interesting snow totals in isolated across the southeastern part of the state.
DOYLESTOWN 1.0 130 PM 10/28
LANGHORNE T 1045 AM 10/28
LEVITTOWN T 1040 AM 10/28
SPRINGTOWN T 720 AM 10/28
SOUDERTON 1.5 1140 AM 10/28
WILLOW GROVE T 700 AM 10/28
As the low rapidly pulled to the north across Canada an unusually cold air mass plunged southward across the Northeast resulting in a heavy lake effect snow outbreak that brought flurries all the way to Philadelphia which was quite an anomaly.
THE LAST TIME SNOW FELL IN OCTOBER IN PHILADELPHIA
WAS...OCTOBER 30, 2002.
Heavy squalls of lake effect snow reached far east bringing heavy snow amounts to western Pennsylvania giving near record level snowfall for the month of October to Erie and Pittsburgh.
Figure 1.3 shows our own JDinWPA having 3.5inches of snow near Butler, PA from pure lake effect. The sun from the next day and high water content of the snow resulted in rapid melting.
November 20-22 Lake Effect Snow Anomaly...Link.
Probably my favorite winter weather event of the winter was a very interesting lake effect snow event. A weak clipper system pulled out of the region as the flow turned more northwesterly. Wind trajectories were near 280 shifting to a more 300degree northwest flow. With H85s unusually cold near -10C and lake temperatures in the 50s, the spark contrast created several large snow squalls. The first snow squall was a Huron-Erie Streamer that reached from Erie, PA to Philadelphia, PA dropping heavy amounts of snow across the region in a very narrow band from Erie to Bradford to St Mary’s to Lewisburg to Selinsgrove to Reading to Coatesville. Snowfall amounts of 8inches were reported in Elk County with amounts near 5inches across Union and Snyder Counties. The band stayed relatively stationary throughout that night. An enhancing shortwave bringing a cold air vortex across central Lake Erie brought more interesting weather the next morning. A cold pocket on the H5 chart brought an enhanced area of moderate low-topped snow which was not visible on NEXRAD radar. Snow amounts in the Harrisburg-Lancaster Corridor were generally around 3inches with most of that on the grass due to the daytime event. Later that day the flow turned more to the 310 trajectory allowing more large streamers to funnel in across Pennsylvania. Snow totals near Pittsburgh reached 2inches with areas in the Laurel Highlands around 8inches near Laurel Summit. Across northwestern Pennsylvania snow amounts were well above a foot in the suburbs of the city of Erie. A large 322 streamer formed later that day bringing another round of heavy snow to central Pennsylvania. State College reported 1.5inches of snow in the band. Harrisburg received another 2inches of snow adding to the daily total of 5inches strictly on the grass and no where else.
Fig. 2.1 shows snow squall for the afternoon of Nov 21st, view to the east from NWS CTP. Photo by Rob Radzanowski, Forecaster.
Snow rates near 2inches per hour occurred as colder funneled into the region with 1000-500mb thicknesses near 518. H85s were near -15C. The following day on the 22nd another weaker 322 band formed and dropped a quick additional 1inch of snow in the Harrisburg area resulting in two day totals of 6inches.
Fig. 2.2 shows the third heavy snow 322 streamer here north of Harrisburg courtesy of my photos. About 4.5inches of snow was on the ground at the taking of this picture.
Overall the event proved to be a very interesting mesoscale feature event with very distinctive Huron-Erie streamer bands. This event brought many areas up to above normal snowfall for November. The area that did seem to miss the snow was across the Lehigh Valley. Just ask jthal57, lol.
December 6-7 Light Clipper Event... Link.
A weak Alberta clipper moved across the state of Pennsylvania. As usual December 5 or 6 always seems to bring the first widespread snow to everyone. I always consider that date the first measurable snow of the year as an average. The snow was generally light across the state with 1-3inches across western and central Pennsylvania. Amounts were a bit lighter to the east, but some areas saw higher amounts in the east thanks to some bay enhancement. The light amount of snow and cold air temperatures resulted in snow covered with scores of accidents on the slippery roads. Snow ratios were also near 20:1 resulting in a fluffy snow. As the clipper pulled away the lake effect machine opened up with high snow amounts across the Alleghany Plateau. Also high winds occurred after the clipper with wind advisories being posted.
...WIND ADVISORY IN EFFECT UNTIL 10 PM EST THIS EVENING...
THE NATIONAL WEATHER SERVICE IN STATE COLLEGE HAS ISSUED A WIND
ADVISORY...WHICH IS IN EFFECT UNTIL 10 PM EST THIS EVENING.
WEST TO NORTHWEST WINDS WILL CONTINUE TO INCREASE THIS AFTERNOON.
EXPECT THE WINDS TO BE SUSTAINED AT 20 TO 30 MPH WITH GUSTS UP TO
50 MPH AT TIMES. THE WINDS SHOULD SUBSIDE A BIT LATER THIS
EVENING...BUT WILL REMAIN BREEZY ALL NIGHT.
December 11-12 Forecast Mess...Link..
One of the larger forecasting busts of the season was for the so called significant ice storm. Winter weather advisories were issued for the state of Pennsylvania along with winter storm warnings. A cold front pushed across the region with generally .5inches of rain. A push of colder air was supposed to move into the region relatively quickly ahead of a low pressure riding up the nearly stalled cold front across eastern areas. The low pressure caused quite the snow anomaly for parts of the southeast. Many parts of southern Texas near the Gulf Coast received a rare snowfall.
Fig. 3.1 shows our own snow pictures from shoreacres of 2inches down in Galveston, TX.
The push of colder never really moved in as quickly as most thought for this system resulting in a forecast bust for the ice storm for most areas excluding the Poconos which received nearly .25inches of ice. The storm did produce a significant rain total for many areas with 2-3inches for many areas.
December 16-17 Significant Winter Storm... Link.
This was one of the more significant winter storms of the season. A stalled quasi-stationary frontal boundary was draped to the south of Pennsylvania. Overrunning moisture brought a mix of snow/sleet/and freezing rain to much of the state. Warm air advection brought a decent amount of snow to many areas across southern Pennsylvania along the turnpike as embedded mesoscale bands formed across the region. One band in particular stretched from Raystown Lake to Carlisle bringing very heavy snow with rates near 1inch per hour. It did take a bit of time for much of the snow to fall as there was some high virga returns across the southern portion of the state. 40dbz returns 4inch amounts in this narrow corridor especially near Amberson Valley across northern Franklin County. As the front lifted northward precipitation turned over to some coatings of freezing rain and sleet. Ice amounts were generally under .25inches. The NWS failed to issue a winter storm warning for the region which caused many issues after the storm as snow/ice criteria reached warning criteria.
Fig. 4.1 shows our own TheRasberryPatch and family out in a few inches of snow that afternoon.
Fig. 4.2 shows the heavy snow returns across the southern portion of the state.
This is was one of the few storms of the season where the highest snow amounts were reported. It was a general 2-4inch snowfall for most areas.
December 19 Ice Storm..."Link.
Another complex storm system of the heals of the recent winter event headed towards the Northeast in what was a very busy weather pattern. Low pressure from the southwestern portions of the United States headed northwest across the Midwest and through the Ohio Valley. Anomalous PWATS brought heavy precipitation across much of the state. Initial warm air advection brought snow generally north of the I-80 corridor but as far south as Allentown. Snow amounts generally were 2-5inches. The La Nina brought this west to east progressive flow.
Fig. 5.1 shows the H5 chart showing the ridge over the southeast and trough over the western United States.
As warm air advected into the upper levels 850s rose above 0C for many locations. Freezing rain occurred in most locations with a general .1-.25inches for the region. Overall QPF totals were relatively light across the state nearly .5inches for most locations.
Fig. 5.2 shows a picture from my location where .1inches of freezing rain occurred.
December 21 Ice Event... Link.
Another weak overrunning type system moved across the state of Pennsylvania. Marginal QPF near .2-.4inches resulted in advisory criteria freezing rain amounts. Highest amounts were across northern Pennsylvania where for a time ice storm warnings were issued. The storm was also highly elevation specific resulting in extremely heavy ice in the higher elevations above 1000ft.
Fig. 6.1 taken by myself on top of Blue Mountain at an elevation of 1220ft shows the heavy ice nearly .4inches where a heavy accumulation of snow. At the valley surface with an elevation of 500ft there were no signs of any wintry precipitation.
December 24 Christmas Eve Ice Storm... Link.
This was a high impact event which was caused by another inland cutter with a low pressure passing through northwestern Pennsylvania. High pressure to the north caused cold air damming to hold its ground causing nearly .25inches for many locations. Many accidents were caused by the ice eventually shutting down part of the PA turnpike in the Lebanon County-Lancaster County corridor. Temperatures eventually rose above freezing for most locations as a southwesterly flow eventually one over from the easterly wind. Temperatures in fact rose into the 50s before the front came crashing through.
Fig. 7.1 shows some of the total ice accretions across Pennsylvania for the event.
Fig. 7.2 shows a radar image of the small shield of precipitation. There is also clear evidence of cold air damming with the northeasterly flow.
January 6-7 The Forecast Bust of the Winter... Link.
Ah, one of the worst forecasts for forecasters in quite a while that sparked controversy that continues to this day. Latest GFS and EURO models showed another overrunning event tracking across the region, but farther south than those of December. This in turn would bring more snow for much of Pennsylvania including southern areas. Winter storm watch flags were issued statewide with the threat of 4-8inches of snow with higher amounts in northeastern areas. Then about 24hours before the event there was a small change in model guidance that had a huge model result. Having put out my snow maps and such about 2hours before, I noticed this difference. Quickly I was able to write my discussion about 15hours before the storm...
Lack of confidence for forecast, therefore no discussion on storm. I believe that much of central Pennsylvania will be dry slotted and then as precipitation moves in, some of it will mix. Accumulations will be lucky to get to 4inches I think at this point. I am not one to give up on a storm, but I have had a bad feeling about this storm all week, just see my posts from a few days ago. I think these warnings may bust badly. I-80 corridor and northward is place to be as frontogensis places heavy snow band at that location. A sharp cutoff can be expected to the south. Then as precipitation moves in due north of low, mixing will take place. What we need to setup is a good initial band across central Pennsylvania as indicated by some earlier model runs on the 700mb RH moisture charts. Whether that will happen or not is a question. I have a feeling some areas in York and Lancaster will really get shafted. In any case I hope I am wrong, but this is how I see things this evening. And I would rather feel good to know that I am firm with my gut than stick with the NWS forecast of warning criteria snowfall just because they have a winter storm warning.
This in fact saved my forecast when the NWS continued with then issuing winter storm warnings. The next day the 850 low tracked farther north resulting in 1inch amounts for Harrisburg where NWS forecasts called for 4-8inches. Even though I did issue my bogus maps, I quickly canceled them. Without sounding conceited, I really do think it was one of my best calls of the winter. I was able to spot the bust well ahead of any other forecasts calls. Therefore as we all went to sleep that night none of us were to disappointed. The track of the 850 low made all the difference. People focused too much on the surface low track. So all in all I guess things worked out at least here even though we missed what could have been a decent snow. The NWS is being continued to be criticized for the terrible call even when it was evident amounts were not going to pan out. These were all supposed warning snows, here are some actual totals...
STEVENSON DAM 1.0 700 AM 1/7 COOP REPORT
PLEASANT GAP 0.5 700 AM 1/7 SLEET
STATE COLLEGE 0.2 700 AM 1/7 SLEET
GRAMPIAN 1.5 700 AM 1/7 COOP REPORT
RENOVO 1.0 700 AM 1/7 COOP REPORT
BENTON 1.1 700 AM 1/7 COOP REPORT
RIDGWAY 1.0 700 AM 1/7 COOP REPORT
HUGHESVILLE 0.5 1013 PM 1/6 SIGNIFICANT ICING
WILLIAMSPORT 0.5 1000 PM 1/6 COOP REPORT
WESTFIELD 1.0 700 AM 1/7 COCORAHS
January 17 Coldest morning in a decade... Link.
January averaged about 3-6degrees below normal statewide making it the coldest since 2003. But on the morning of January 17 with high pressure, temperatures bottomed out to some of the coldest temperatures in a decade with negative readings in just about every single county in Pennsylvania. Here just north of Harrisburg I got down to -3, which was the coldest temperature since having my vantage pro2. A record low was also broken in Williamsport with -13 breaking the record of -12 set back in 1982. Parts of the Northeast received amazingly cold temperatures with Maine reaching their coldest temperature in the state's history in the -50s.
Fig. 8.1 shows some of the morning lows across the region.
January 27-29 Largest Winter Storm of Season... Link.
The largest winter storm hit at the end of January. Another overrunning system was progged to hit the region with model guidance in fair agreement. The low trekked across the Missouri Valley and across the Ohio Valley spreading precipitation in its path. 700mb frontogenisis created moderate snow to break out across southern Pennsylvania with snow rates at times near 1inch per hour. Warmer air aloft moved across the area changing western Pennsylvania relatively quickly over to ice and then eventually plain rain as both 850s and surface levels climbed above freezing. A round a bit earlier than the main event aided in some light snow across southern areas with 1-2inches south of the turnpike. As the main low moved in the heaviest gulf moisture was widespread over the region. Stubborn cold air hung tough for several hours around the turnpike on northward giving away very decent snow totals. Dendritic growth was excellent along with great Omega Values. With the initial round H85s were near -15C but quickly rising to +-2C of 0C. Total QPF for the event was 1.5inches for most areas. The precipitation generally was in the light snow to heavy snow to heavy sleet to light freezing rain for most locations. This encased the snow making for the lovely concrete which created a snowpack for nearly 20days here just north of Harrisburg.
Fig. 9.1 shows the surface map on the 28th of January.
Overall my forecast for the storm was by far the best of the winter. And going back I really do not think I would make any changes.
Fig. 9.2 shows my verification map with my forecast and actual snow totals plotted on top of it.
February 3-4 Freak Mesoscale Event... Link.
The strangest event of the winter unfolded as a coastal storm affected parts of eastern Pennsylvania. A low pressure tracked well off the coast, but the deformation band of snow formed across the Philadelphia and southeastern Pennsylvania area giving over 8inches of snow to KPHL Airport, breaking the record for the day. Many other snow totals in the 3-6 range were recorded. As the coastal low pulls away, a very unusual mesoscale event occurred. A pocket of extreme cold air in the H5 chart tracked across southern Pennsylvania. Similarities were very obvious to the November event. A lake effect snow band formed out of the Mt. Gretna mountains of 800ft elevation on south through Lancaster County tracking through Manheim and Lancaster creating a once in a lifetime 5-8hour event. Heavy snow unfolded with 3inch per hour snow rates. Over 12inches of snow was reported in the central portion of the band. The high resolution computer models were accurately able to predict this intense squall, but off course placement was a little off. Snow ratios and beautiful dendrites were able to produce this abnormal amount of snow over the very isolated area.
Fig. 10.1 shows our own Snowlover2010 and 5inches of snow.
Satellite feeds were able to interesting pick up on where the snow hit.
Fig. 10.2 visible satellite for next day.
The following evening another snow band occurred this time taking on the classic 322 band. High snow ratios near 20:1 occurred along with very cold temperatures with readings in the teens. The band hit State College and south through Lebanon. 2inches of snow I recorded, but amounts up to 4inches were reported in Lebanon County in Campbeltown by our own TheRasberryPatch. High winds also blew in the storm creating drifts up to 8inches along previous snow banks from the January system.
...AN BAND OF DANGEROUS SNOW SQUALLS WILL AFFECT NORTHEASTERN
JUNIATA COUNTY...NORTHEASTERN PERRY COUNTY...NORTHERN DAUPHIN COUNTY
AND SOUTHWESTERN SNYDER COUNTY THROUGH 915 PM EST...
AT 718 PM EST...A NORTHWEST TO SOUTHEAST BAND OF DANGEROUS SNOW
SQUALLS WAS ALONG A LINE FROM 4 MILES SOUTH OF MILLHEIM...TO NEAR
MCALISTERVILLE...MILLERSTOWN...AND PORT ROYAL...MOVING SOUTHEAST AT
VISIBILITIES IN THE SQUALLS WILL RAPIDLY DROP TO NEAR ZERO AT TIMES.
THE SNOW WILL FALL ONTO RELATIVELY WARMER ROAD SURFACES...WHICH WILL
CAUSE IT TO QUICKLY MELT AND THEN RE-FREEZE. THIS COULD CREATE VERY
ICY CONDITIONS IF THE ROAD SURFACE IS UNTREATED. MOST OF THE HEAVIER
SNOW AND POOR VISIBILITY WILL OCCUR NEAR AND TO THE NORTHEAST OF
Well sitting here now nearly the end of February, it is hard to believe another winter passed quickly before our eyes. This winter was marked by some extreme suffering for those south of the Pennsylvania turnpike. My seasonal total stands at 22.40inches which is below normal, but areas just south of the turnpike are only at around a foot of snow. This season was a very progressive year thanks to the La Nina. The flow was embedded with too many shortwaves to allow any significant cyclongensis to form along the coastline. The Alaskan Vortex also plagued us for much of the season with a negative PDO and negative PNA. Also we lacked the true western-based NAO. There complex progressive flow caused the models to have a rough time this winter causing o so much heartbreak for many. Also the cold and dry January caused heartbreak as we had the opportunity for snow with the cold temperatures. One thing to keep in mind is that it is never good to have a dry arctic blast of record cold air. It never bodes well for snowfall. The snow drought continues across the Middle Atlantic for another year. To me the winter was very interesting with the strange lake effect snow mesoscale events and odd October snowstorm. Honestly if we would have had a large 6+ snowstorm I would call this winter a success and memorable. But another years goes by since our 10.5inch St. Patrick's Day snowstorm of 2007. In any case there is still a few days of meteorological winter left and about a month of astronomical winter. Looking long term wise I really just do not see any good snow opportunities. A few long wave signs of a stormy and cold mid March followed by late Spring could bring another maybe cold April. But I am pretty sure with a warm start to March. Overall I would call my temperature forecast for the winter a success with below normal temperatures. My snowfall forecast of normal snowfall will pan out for some areas, but not the southern and eastern parts of the state. In any case I will leave verification for another blog. My winter forecast period ends at the end of February. My forecast was for December, January, and February, the meteorological winter months. I hoped you enjoyed this recap and it will bring some fun memories back from the winter. Also take some time when you are bored and check out some of the past blogs. Some of our conversions are very comical to read! Have a great day.
Here are some special blog links...
-Middle Atlantic Winter Blog...Link.
-Part I Winter Forecast... Link.
-Part II Winter Forecast... Link.
-Winter Recap 2007-2008... Link.
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.