Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 12:43 AM GMT on March 01, 2010
The cutoff low will finally pull away to the northeast before strengthening once again over the open waters of the cold North Atlantic scraping eastern New England with some moderate snow. Meanwhile upper level ridging aloft will allow conditions to dry out across the Northern Middle Atlantic before prognostics suggest another Miller A low pressure to form along the southeast. At this time the cyclonic regime near Newfoundland will prevent the next low pressure from causing major impacts to the northern Middle Atlantic with steering currents about 100mi too far east for a favorable track; but I still am closely monitoring the situation for any changes. Light rain/snow is possible over the region late Tuesday through late Wednesday with dry conditions the rest of the week with near normal temperatures to slightly below.
"Afternoon Thoughts" (Updated 2/28)
As I stare across on the tumultuous sky and landscape of the last day of the meteorological winter, it is evident extreme weather has laid its foundation this winter as a burdening force even into the twenty-first century. A few heavy snow/rain squalls continue to lash through the region this afternoon not as an ominous sign, but as a farewell to winter and a calling to Spring. We had quite a run this winter with persistent cold and a myriad of historical storm systems each with unique characteristics. While extreme cold was a distant rarity, the persistence of the chill in the air was unusual. The concept of robins feeding under the budding of hollow trees branches is enlightening not only to those whose brittle bones have been under constant chill, but even to the youth who cherish each snowflake as unique as the next. The concept of why people like snow is unique in itself; perhaps we enjoy the display of the disruption snow causes to our routine scheduled life. Maybe it installs fond childhood memories of one's Flexible Flyer sled or building snowmen on a day off school. But maybe it is as simple as the effervescent feeling of tranquility on a white winter landscape on the mountainside. Accompanying the four seasons are a plethora of unique weather patterns that while are all correlated together, they each have their own characteristics. In fact Earth's most extreme storms are the simple thunderstorms. So as Spring approaches, tulips and daffodil bulbs appear, crocuses open in brilliant purples and yellows, and the robins begin to call in the morning, we see that March is a transition month. While I cannot tell you whether it will snow again this winter or whether a thunderstorm is brewing on the horizon, I can tell you warmer weather is certain. This blog sure has grown over the past few years, and I hope most everyone stays for another exciting chapter of weather through Spring and Summer. Also members feel free to vote in the new poll for the week on the right side of the screen. Have a great day!
"Current Surface Plot"
(Courtesy of HPC)
(Courtesy of Wunderground)
(Courtesy of NOAA)
"Forecast Discussion"(Pennsylvania, Maryland, Delaware)(Updated 2/28)
Current water vapor loops show the left-over vortex of energy beginning to merge with a mid Atlantic low pressure northeast of Bermuda. This 996mb low will undergo cyclogenesis as the energy converges. With anomalous blocking upstream, this low will also retrograde slightly west-southwest. This will allow the cyclonic flow to stay immersed across the Northeast. But with H85s rising above -10C, weak ridging aloft will cap off most precipitation excluding flurries. NAM Skewt T charts also produce a bit of freezing rain Monday through Monday across the higher elevations of western Maryland and western Pennsylvania with little ice crystal growth aloft. But a 1024mb high pressure to the west will allow low inversion heights to preclude precipitation for Monday for the entire Northern Middle Atlantic. MOS guidance has been running a bit low for the past two weeks, this fact coupled with March sunshine will allow for near normal climatology highs for Monday across the region with the closest measureable +.01in QPF located towards New England. Under the cyclonic flow, widespread strato-cumulus will be widespread across the region. HIRES NMM/ARW mesoscale models indicate a bit of warm air advection Tuesday as the flow turns a bit more southwesterly with 1000-500mb thicknesses rising to near 538-540dm. The 980mb low pressure south of Nova Scotia will continue to lift northeast across the North Atlantic shipping lanes. Again high/low temperatures look to be a tick above MOS/Climo for Tuesday with around 75-100% sky cover for most areas. HIRES NMM shows a developing low pressure towards the panhandle of Florida developing around 1000mb with rising PWATs across the Southeast by Tuesday evening.
With a fast 500mb flow out of the western United States, the trough axis will be tilted a bit too positively with the trough axis displaced too far east allowing the low pressure to stray southeast of the northern Middle Atlantic with minimal affects. But NAM/GFS correspondence does indicate a weak shortwave rotating through the base of the trough in the same time period allowing for minimal QPF over the entire region. GFS/NAM seem to have a good hold on the closed low with QPF at or around .1in. Warm boundary layer temperatures with 2m dew points around freezing for I-95 shows a general rain/snow mix for the lowlands below 500' on Tuesday as light precipitation across the region. But towards Tuesday night a steady light snow may develop throughout the region with some light wet snow accumulation especially above 500ft. Accumulations generally appear to be about 1-3in with little to no accumulation south of the Mason-Dixon Line Wednesday night. IFR ceilings with low stratus courtesy of the easterly maritime flow will persist through Wednesday with spotty rain/snow showers over the region as highs run about climo. QPF totals for Wednesday range from a trace to .04in. Most areas will only see spotty drizzle especially over Maryland, Delaware, and southeastern Pennsylvania. Finally towards Thursday the ECMWF indicates a 1024mb high pressure nosing out of the Mississippi Valley with ridging aloft moving across the eastern United States as H85s rise to near -2C. 2m ECMWF guidance suggests highs approach 50-55F for many areas by Friday/Saturday. As the low pressure well offshore pulls farther northeast, clearing skies will result in this Thursday through Saturday time frame.
(Courtesy of Penn State Meteo.)
"Current Water Vapor Loop"
(Courtesy of Penn State Meteo.)
"7-Day Zonal Forecast Outlooks"(Pennsylvania, Maryland, and Delaware)(Updated 2/28)
Monday- As the northwest flow begins to relax on Monday, little additional snowfall will occur over the lake effect snowbelts of Maryland and Pennsylvania. Additional accumulations will be limited to a coating to one inch favoring southern Somerset County, Pennsylvania in the morning hours. While a bit of lake influence persists, widespread cloud cover will be across western Maryland and the western half of Pennsylvania during most of Monday. A downsloping flow will allow for sunshine to persist over eastern Pennsylvania, most of Maryland, and all of Delaware. With widespread sunshine, a downsloping flow, and a stagnant air mass, highs towards average are likely ranging from 40-48F for much of the northern Middle Atlantic with higher numbers favoring metropolitan locations along interstate 95. Monday night will feature increasing clouds from west to east as a weak wave approaches the region while a coastal low tracks will offshore with minimal effects. A bit of freezing drizzle should also be mentioned across the Laurel Highlands and northwest mountains of Pennsylvania with low freezing/cloud levels. Freezing drizzle though will be spotty and confined to areas above 1800ft in the lake effect snow belts. Low temperatures appear mild as a bit of a tight gradient allows for some gusty winds to around 35mph towards evening and overnight. Lows will range from 30-38F with lows near 40F towards southern Delaware and Washington DC.
Tuesday- Increasing and lowering clouds in the morning will pave way for a dreary early March day region wide. The weak wave over the region will allow some light precipitation to develop. Relatively high dew points and surface temperatures will allow for a mix of rain/snow below 500' region wide. Little to no snow accumulation is likely including the higher elevations during the day with melted precipitation amounts around a few hundredths of an inch. Highs will be near normal ranging from 36F over the western and northern higher elevations to around 45F near the Chesapeake Bay coastal plain with pure rain showers. Tuesday night temperatures will fall near wet bulb heights with lows around 31-35F with light snow north of the Mason-Dixon Line and a mix of rain/snow showers to the south. Amounts will be very light with any snow accumulations confined to the ridge tops ranging around 1-3in of wet snow. Any rainfall amounts will be below .1in. Widespread cloud cover will allow relatively uniform temperatures region wide overnight. With low level inversion and moist relatively humidity surface values, a bit of fog may form Tuesday night limiting visibilities around 1mi especially downwind of the Alleghenies.
Wednesday- The weak wave of low pressure will quickly depart, but widespread clouds will persist much of the day region wide. A few spotty rain/snow showers are likely throughout the day with below measurable probabilities causing just a dampening of the soil. Morning fog may persist across the Appalachian Mountain valleys and lowlands with a melting snowpack and warmer temperatures aloft. But with a bit of an easterly breeze, visibilities will only be limited to around 1-3mi dissipating by noon. Highs will rise to similar values to that of Tuesday ranging near normal from 38-47F with the highest values towards Washington DC and southern Delaware. Wednesday night will feature clearing skies from west to east with high dew points at the surface overnight favoring once again light fog formation after midnight. With high dew points and cloudy skies at times lows will be above normal ranging around 28-34F.
Thursday/Friday- Relatively similar conditions will occur either day with a melting snow pack and steadfast sunshine as a ridge from the west approaches the region with high pressure. Under the southwest flow, highs will approach the warmest values since about early to mid January giving a little taste of Spring. At this point highs should range from about 47F over the western and northern mountains to around 55F over southern Maryland and southern Delaware into southeastern Pennsylvania. Lows both nights will also be mild ranging around 30-36F across the region with slightly higher numbers towards the Johnstown-Bradford corridor. Slightly warmer values are also likely towards Saturday and Sunday with sunshine across the entire Northern Middle Atlantic.
"Current River Ice Reports and Ski Conditions" (Updated 2/28)
With record snowfall occurring across the entire northern Middle Atlantic, it is no surprise the ski season will be one to remember. Upslope continues across the Laurel Highlands and Garret/Alleghany County region in Maryland. But as weak ridging aloft approaches the region, it will act as a CAP allowing for lowering inversion heights and a loss of ice crystal growth allowing for only freezing drizzle on Monday before conditions begin to clear. Snowfall at Seven Springs is being reported at 227" for their seasonal total in Somerset County, Pennsylvania with snow totals near McHenry, Maryland surrounding Deep Creek at around 250" of snow for their seasonal total. Ski Conditions remain excellent in western Maryland and western Pennsylvania with an additional C-2in likely through Monday evening especially above 2000ft. Across the south central mountains of Pennsylvania Whitetail, Roundtop, Liberty, and Sawmill are all reporting a fresh 3-8in from this past weekend with higher drifts. Conditions are being reported as excellent. Towards the Poconos south to Blue Mountain Ski Resort an additional 10-20in of snow fell across the region with excellent conditions under fresh powder. Warmer temperatures look to be in store for much of the northern Middle Atlantic as temperatures approach 40-45F for a majority of the week. It appears the peak ski season is over in correlation with the rising March sun angle. An offshore low pressure originating out of the Southeast will move northeast along the coast. But at this time it appears most of the precipitation will be offshore closer towards the center of circulation. But with that being said, an easterly flow will allow for low stratus Tuesday through late Wednesday accompanied by light snow mixed with rain below 500ft. A new 1-3in of snow is likely especially at or above 500ft in this time frame with most of the accumulation occurring Tuesday night and/or Wednesday night with the absence of the strong March sun. Towards the weekend strong ridging out of the southwest will give way to above normal temperatures at or above 50F by Friday/Saturday. As far as local water way ice conditions, the ice fishing season looks to be coming to a close as temperature rise above 40F for daily max averages accompanied by strong March sunshine. Little to no ice remains on main stem rivers including the Alleghany, Delaware, Susquehanna, and Juniata River basins. Ice remains on local smaller ponds and lakes, but looks are deceiving as conditions remain too thin and dangerous to attempt to walk on. Winter is abruptly coming to a close as meteorological Spring begins March 1. If I have not already mentioned, this is the last weekly weather winter format blog for the season. The new Spring format will debut next weekend with new special feature discussions, maps, etc.
-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 2/28)
As daytime average max temperatures increase along with H85 anomalies, the sharp contrast between air and water temperatures around the Great Lakes becomes much more uniform. Therefore this will limit any lake induced precipitation event to only have marginal and nuisance effects. A 290degree flow continues across the cyclonic regime as the retrograding cutoff low pulls away sharply to the northeast. As drier air advects into the region and H85s rise above -10C, inversion heights will bring a CAP to the consistent orographic precipitation over the Laurel Highlands in Pennsylvania and western Maryland. Mesoscale guidance is event indicative of lowering ice crystal growth heights highlighting the potential for some freezing drizzle above 1500ft in western Pennsylvania and western Maryland towards Monday and Monday night. IFR conditions will continue to lift at the western air terminals with lifting stratus by Monday. Any additional snowfall through Monday night will only be a coating to two inches favoring southern Somerset County, Pennsylvania. By Tuesday any flurries will be limited to the lake shore near Erie. As another low pressure undergoes cyclogenesis well offshore, another induced northwest flow will persist over the Middle Atlantic from late Wednesday through mid Thursday as winds turn to around 320degrees. A few lake effect snow streamers may cause 2-4in of snow in the northwestern snowbelts near Chandler's Valley up through Meadville and Corry. Lighter 1-3in snows will persist in the upslope belts of the Laurels. The core of -10C H85 temperatures will quickly pull out of the region allowing for any light snows to end by Friday morning before milder air advects into the region with a southwestern Mississippi Valley 1024mb anticyclone shifting the winds to the southwest. At this point any lake effect snow looks to be marginal in the coming week favoring Wednesday through Thursday, but with unimpressive dendritic heights, Omega levels, and weak lapse rates, any streamers will remain low topped below 10,000ft limiting accumulations. Also with low snow rates, snow will be difficult to accumulate during the daylight hours favoring the best chance of accumulation being Wednesday night. Current GFS/NAM guidance suggests QPF totals around .2in with 15:1 ratios for the higher elevations in the lake effect snow belts. Winter weather advisory criteria may not be met widespread, but the wet snow may still cause a few isolated travel problems across elevations above 1800ft. By Friday and Saturday high pressure will dominate with region wide sunshine.
"Current Lake Erie Wind Direction and Speed"
(Courtesy of NOAA)
"Current Lake Erie Water Temperature"
(Courtesy of NOAA)
"Long Term Outlook" (Updated 2/28)
The persistent cold is finally dwindling away along the eastern seaboard. This fact coupled with rising climatology averages shows a distinctively direct correlation to a warm period during the next two weeks. While the NAO continues to remain in a negative regime, the upstream Arctic Oscillation is finally showing signs of heading towards positive values after a record breaking multi-month period of negative values. In fact this brings up an interesting point... The lack of arctic air this winter can be directly associated to the displaced Polar Vortex in the Northern Hemisphere directing the arctic air towards the European and Asian side of the globe. In fact anomalies in this region are well below normal with the second coldest temperature ever recorded in Europe recently occurring in Russia. This is also evident in Greenland and Canada where a record warm winter verified across much of the northern Plains in this region due to the lack of cross polar flow. If there had been no anomalous blocking across the Arctic Circle, you can bet this winter would have been a disaster for much of the United States. The negative NAO and negative AO caused just enough cold air to couple with the active subtropical jet courtesy of the El Nino. In all actuality, while most all winter forecasts called for a snowy winter, we were quite lucky the Atlantic and Pacific turned favorable just in the nick of time after a terrible November. Also of critical note is the favorable MJO, which has been steadfast in phases 6, 7, and 8 which support troughing along the eastern seaboard. All four historical east coast snowstorms occurred during phase 8 showing the direct correlation which was existent even before the winter. The MJO, which showed little forcing January, caused the mild spell January. This is evident of how fragile the pattern actually was this winter despite the historic turnout. With this all being said, the MJO looks to show signs of shifting towards phase 1 with the AO rising to near positive values. For the first time since early to mid January, 11-15 day H85 temperature outlooks show well above normal anomalies for much of the United States under a zonal Pacific flow. It appears above normal temperatures are likely beginning around the 5th of March. While snowfall chances remain limited being the end of winter, this pattern swing does not automatically eliminate snow. As for precipitation, it appears normal to below normal precipitation is likely through midmonth despite an active subtropical jet coupled with a moderate El Nino, which though should be noted as steeply weakening with rapidly lowering SSTs in Nino regions 1/2 and 3.
"Current NAO and PNA Predictions"
(Courtesy of NOAA)
"Anchorage, Alaska Tower Cam"
*Note I am only posting this tower cam until snow starts falling over the northern Middle Atlantic, lol. For now we can all be jealous of the Alaskan snow.
"Monthly Outlook" (March)
February sure has been a memorable month for those with concerns across the viewing region. In fact century old records have been broken for many large cities and towns across the northern Middle Atlantic with even snowfall being recorded on the ground in at least 49 states during the February 12-13 period, which many climatologists are hard pressed to find any other date with such widespread snow cover. The NCDC reports nearly 68% of the nation snow covered as of February 13th with an eight inch average depth. With temperature anomalies also well below -2SD for much of the United States, this has certainly been a February of wintry notation. While the month is generally about 1/2 over and an end to the meteorological winter is quickly approaching, more wintry precipitation will likely continue for the eastern seaboard. For more details for the last two weeks of the month consult the long term disco above. As for a February forecast, due to time constraints unfortunately I was unable to post one. But on second glance of my winter forecast, it clearly advertised February being a very snowy and cold month in fact the snowiest of the winter. Despite what the final two weeks of the month show, these statistics have already been verified. Soon or perhaps now many will be basking in the threat of spring-like weather which is not too far off. It is evident based on teleconnections the worst is over as far as arctic air and climatology means. For those interested in my winter outlook verification blog, it will be issued upon the first week of March as the meteorological winter comes to a close. Now as we look towards March teleconnections diverge... Global models including the GFS/ECMWF begin to lose direct correspondence in forecast similarities after the 10 day time frame. ECMWF weeklies continue to advertise anomalous blocking as we continue in this record -4 AO with troughing over the east coast. But the GFS highlights a zonal flow with Pacific air flooding the nation with cold air bottling up towards Canada. What is interesting this year has been the lack of arctic. Due to the polar vortex being displaced a bit too far north, we have been close to record cold air, but it is just a bit too far displaced. In any case this looks to continue. As common with El Ninos, an active southern stream will continue. But current Nino 3.4 region SSTs indicate a general cooling regime with weakening into low end moderate stage. MJO on the other hand using GEFS supports more of an ECMWF solution. Using a few analogs up my sleeve, climatology, and teleconnections I support a mean forecast of the following for the month of March...
Temperature- I look entitled to enter a pretty typical temperature anomaly forecast for the month averaging from (-0.5)-(+0.5) F across the entire northern Middle Atlantic. This being said I favor guidance for a cooler pattern for the first week or two of the month with temperatures around -5F averages each day; nothing overly cold. Then I believe the pattern radically swings around midmonth or potentially earlier to a much warmer flow as we pardon goodbye to a historic winter. In fact the pattern change is critical for timing as it appears once we swing the pendulum warmer; it is not going to come back. Previous patterns this winter even back into the fall of 2009 favor about 30 day patterns so the timing on this troughing over the east is coming to an end soon. I would not be surprised if the month rounds things on the warmer side of the forecast more so than verifying colder than normal.
Precipitation- Considering climatology of moderate El Ninos on the weakening trend and the considerably active southern stream, I am inclined to lean towards the wetter side of guidance favoring above normal precipitation for the month across the entire northern Middle Atlantic. As for snowfall which is really what most people are concerned with, I will go with normal snowfall for most regions with the higher threat of snow being during the first week of the month before the large pattern change.
"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- T
Monthly Total- 0.00in
Seasonal Total- 70.10in
October Total- Trace
November Total- Trace
December Total- 16.0in
January Total- 2.1in
February Total- 52.00in
March Total- 0.00in
Winter Weather Advisories- 7
Winter Storm Warnings- 3
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 2
Winter Storm Watches- 4
Lowest High Temperature- 18.8F
Lowest Low Temperature- 9.3F
Wind Chill Advisories- 0
Wind Chill Warnings- 0
(Winter Storms Stats)
Dec 5 - 1.5in - First accumulating snow of season
Dec 8-9 - 2.5in - Snow changed to plain rain
Dec 13 - .1in - Freezing rain
Dec 19 - 9.0in - Heavy snow, higher amounts to south
Dec 31 - 3.0in - 2.5hr warm air advection event
Dec 31 #2 - .2in - Freezing rain/sleet later in day
Jan 8 - 1.5in - Light snow associated with clipper
Feb 2 - 3.75in - Weak coastal storm
Feb 5-7 - 19.0in - 10th largest snowstorm on record
Feb 9-10 - 20.5in - Blizzard conditions/snow depth up to 36in
Feb 15-16 - 1.25in - Light snow from clipper
Feb 25-26 - 5.25in - Wind blow/drifting cutoff low
Feb 28 - 1.0in - Wet snow
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