Heavy Snow Squalls for Northeast Post Storm...
A double low system will move through the Northeast generally with heavy rain for most areas along with some wintry precipitation for northern New England. Behind the low complex, arctic air will move across the region in correspondence with a very impressive jet streak. This vortex will enhance an area of snow squalls, which will affect many areas with advisory or sub advisory snows. Flash freezes are likely for many areas on Friday along with an increasing lake effect snow cyclonic flow. Winter will be in full force on Friday and Saturday. Winds will also increase to advisory criteria.
Current Surface Plot...
(Courtesy of HPC)
Thoughts on January 11-14 Storm System and Lake Effect Snow...
2-5pm Wednesday: Strong WAA and a southerly jet will continue to allow temperatures to rise over the region in correspondence with the max diurnal heating of the day. 1pm surface observations indicate temperatures above freezing for all locations across Pennsylvania, Maryland, and Delaware. Also temperatures across New England are above freezing given clear skies on the visible satellite. Dew points are beginning to rise across southern areas as the southerly jet increases moisture and milder temperatures. A departing 1024mb anticyclone over New England will allow a CAD situation to unfold for northerly locations across New York State, Vermont, New Hampshire, Massachusetts, and Maine. By 5pm rain will be spreading across Pennsylvania and New Jersey with rates around .1in/hr in some areas. Cirrus will begin to thicken over New England by evening preventing temperatures from falling due to radiational cooling. Therefore temperatures will range from 34-38F across the areas north of the Massachusetts Pike into Vermont and New Hampshire. Dew points will remain in the 20s.
5-10pm Wednesday: Stratiform rain will continue to spread over the entire Northeast edging into southern New England. Rates will range from .1in/hr to .2in/hr especially towards New Jersey. As rain moves into areas north of the MA pike, evaporational cooling will allow for a quick drop in H85 thermals below 0C. But WAA will prevail under a strengthening LLJ. Any snow will not last as guidance indicates a mid level warm layer around 925mb. Snow accumulations will generally be under 1in as far north as southern Vermont and New Hampshire. As the warm tongue positions across southern New England, sleet will increase in some areas from Worcester on northward. Sleet amounts will also remain below 1in. 2m temperatures will fall from the mid to upper 30s into the lower 30s. Rain will fall heavy by 10pm over parts of Maryland and Washington DC with QPF totals up to .75in up to this point.
10pm-12am Wednesday- As WAA continues to increase thermal heights over southern New England, any sleet will change to freezing rain. This will be prevalent across parts of the Adirondacks through the Green and White Mountains. Freezing rain will also occur across the Berkshires and as far south as the hills near Worcester. But 2m temperatures will rise from the low 30s into the upper 30s slowly. Any freezing rain amounts will be less than .1in. Rain will begin to end across southern areas by early morning Thursday with QPF totals around 1in near Washington DC.
12am-4am Thursday: The double barrel low will begin to move up through Pennsylvania and New York state with H85s increasing to near +5C over southern Pennsylvania. Rain will be ending as far north as the Mason-Dixon line. An increasing southerly flow will allow temperatures to rise into the mid 40s into the I-95 corridor from Connecticut on southward. The anticyclone to the northeast will begin to weaken and depart allowing the confluence flow to wane. Heavy snow will begin to fall across northern Vermont and northern New Hampshire will amounts around 4-6in. 925mb temperatures will rise to near +1C to the Canadian border changing any snow to sleet and freezing rain. The surface lows will be rapidly advancing into Canada quickly shutting off precipitation as far north as the tristate region.
4am-8am Thursday: This period will feature any wintry precipitation changing to light rain and drizzle over southern New England. Total QPF in this region will be around 1-1.25 inches. Heavy snow will be falling across northern Maine. Amounts will exceed warning criteria in this small area. Meanwhile an arctic front will begin to move into the eastern Great Lakes. Clouds and warmer air across the entire Northeast will only provide areas of drizzle and low level fog. Temperatures will rise into the lower 50s across the I-95 corridor. Any ice or snow that accumulated along and south of the MA pike will quickly melt even across Pennsylvania and New York State in the higher elevations.
8am-2pm Thursday: The arctic front and associated ULL over Ohio will quickly advance towards western Pennsylvania at the end of this period. A bit of sunshine may occur in the dirty warm sector especially for southern and eastern areas. H85s will drop below 0C once again into western New York and western Pennsylvania. Generally cloudy with occasional drizzle and mild temperatures will be ongoing across the entire Northeast. Any snow or sleet over northern Maine will begin to come to an end.
2pm-8pm Thursday: A 992mb low over Michigan will slowly advance east associated with a strong pool of cold air associated with a series of vortices spinning into Pennsylvania. The arctic front will slowly progress over western Pennsylvania, western New York State, and western Maryland. An increasing pressure gradient will allow winds to increase behind the front along with a developing area of QPF as lapse rates increase in correspondence with a vigorous piece of energy. The atmospheric column will begin to cool over western areas rapidly changing rain to heavy snow with strong winds.
8pm-12am Thursday: A blossoming area of QPF over western and central Pennsylvania will be associated with a high-impact snow event. Total QPF will be around .25-.6in. This will be associated with a period of heavy snow from western Maryland north into western New York State. 1000-500mb thicknesses will drop sub 530dm with rapidly increasing snow rates. The strong northwest flow will along wind sustained to increase near 20-30mph with gusts up to 55mph. This will be wind advisory criteria. Temperatures will rapidly fall sub 30F. Snow ratios will increase to 20:1 in addition with increased orographic lift combined with lake enhancement. This will be a 2-4hr period of heavy snow with amounts around 3-6in along and west of the Alleghany Front.
12am-6am Friday: This band of QPF will shift northeastward as a 988mb surface low moves into central New York State. As the post frontal precipitation moves eastward, it will extend ahead of the 0C H85 line. This will allow precipitation to initially be rain, but rapidly change to snow. Flash freezes are likely all the way to the coast. High temperatures will be reached in the morning hours and fall into the 20s throughout the day for all areas. The best dynamics will shift into New York State and western New England. Squalls will begin to weaken as they head east of the Alleghany Front. Snow accumulations will begin to focus across central New York. Spotty 1-2in amounts are likely from Washington DC to White Plains, NY but generally most areas will be at a coating or less. Snow accumulations of 3-7in are possible into western New England especially along and west of the favored upslope regions in the Berkshires and on northward. Advisories will likely be issued for a widespread area given flash freeze, falling temperatures, high winds, and temporary heavy snow. Short periods of blizzard conditions are possible into north central Pennsylvania and central New York State.
6am-12pm Friday: The arctic front will push towards I-95 and the Atlantic coast with brief rain changing to snow showers as the column cools. Little to no accumulation is likely. Winds will be easily advisory criteria across the entire Northeast viewing area. Temperatures will continue to fall and the deformation axis of snow will be waning and moving through northern New England. A west-northwest flow will prevail as temperatures drop below H85s drop below -10C. The lake effect snow machine will begin to kick in across the typical snow belts associated with a 300 degree flow. The initial flow will be westerly with bands setting up near Buffalo and Watertown. The Ontario band will shift south into Oswego county, New York.
12pm-8pm: The lake effect snow machine will rapidly increase in this time period as the flow shifts to the northwest. Bands will be organized in a multi-band setup with only moderate accumulation. This flow will aid the upslope favored regions from western Maryland through the Laurel Highlands in Pennsylvania. Heavy upslope snows will begin across the Berkshires into the Greens.
8pm-Saturday morning: The northwest flow will begin to relax as the pressure gradient weakens and winds begin to drop below advisory criteria. Upslope snows will be ongoing in this period with total accumulations of 12in+ for northern Vermont particularly towards Mt. Mansfield and Stowe. Amounts of 6-12in will be more likely across the upslope regions in the White Mountains and Berkshires. 6-12in amounts are also likely over western Maryland into the Laurel Highlands through the snow belt regions of northern Pennsylvania. New York State accumulations will generally be a widespread 1-4in with localized 6-12in amounts for the favored banding locations across the eastern finger lakes towards Cortland county.
By Saturday afternoon, high pressure and increasing heights will begin to end the lake effect snow machine.
(Courtesy of NOAA)
(Courtesy of NOAA)
1. Heavy stratiform rain with total amounts ranging from 1-1.5in. Recent dryness will likely prevent any flooding.
2. Freezing rain and sleet is likely for parts of northern New England affecting travel through Thursday late morning.
3. Heavy snow squalls likely across the entire Northeast Thursday night into Friday with light accumulations.
4. Winds will increase to 20-30mph sustained with gusts to 55mph; advisory criteria.
5. Flash freezes likely all the way to the coast with rapidly falling temperatures Friday. Widespread travel impacts.
***The final snow map for the entire Northeast includes total accumulations for the entire event including the synoptic storm, ULL, and lake effect. This does not indicate total snow depth as snow may melt before the arctic air floods into the region. The Pennsylvania snow map includes both lake effect and snows from the upper level low.
Current Great Lakes Water Temperatures...
(Courtesy of NOAA)
Current Lake Erie Wind Direction and Speed...
(Courtesy of NOAA)
Current Lake Erie Water Temperature...
(Courtesy of NOAA)
Selected City Accumulations for the Northeast...
Hagerstown, MD- Rain then a coating to 1in of snow with snow squalls.
Baltimore, MD- Rain followed by snow squalls; coating to 1in.
Salisbury, MD- Rain followed by scattered snow showers; no accumulation.
Pittsburgh, PA- Rain then a period of heavy snow then snow showers; accumulations 2-5in
State College PA- Rain followed by heavy snow squalls; accumulations 1-4in
Williamsport, PA- Rain then heavy snow squalls; accumulations 1-2in
Altoona, PA- Rain then a period of moderate snow showers followed by snow showers; accumulations 2-4in
Harrisburg, PA- Rain then scattered snow squalls; c-2in of snow possible
Lancaster, PA- Rain followed by scatted snow squalls; c-1in of snow possible
Philadelphia, PA- Rain then scatted snow showers; no accumulation
Allentown, PA- Rain then scatted snow showers; a coating of snow possible
Scranton, PA- Rain then scatted snow squalls; 1-2in of snow possible
Washington, DC- Rain then scattered snow showers; a coating of snow possible
Wilmington, DE- Rain then scattered snow showers; little to no accumulation
Dover, DE- Rain then scattered snow showers; no snow accumulation
Trenton, NJ- Rain followed by scattered snow showers; a coating of snow possible
New York City, NY- Rain then scattered snow showers; no snow accumulation likely
Poughkeepsie, NY- Rain then scattered snow squalls; 1-2in of snow possible
Binghamton, NY- Rain then a period of moderate snow; 1-4in of snow possible
Ithaca, NY- Rain then a period of heavy snow followed by scattered snow showers; 3-7in of snow possible
Albany, NY- Rain then scattered snow squalls; 1-2in of snow possible
Hartford, CT- Rain then scattered snow squalls; c-2in of snow possible
Concord, NH- Light snow 1in accumulations, freezing rain .1in accumulation then rain followed by snow 1-4in
Providence, RI- Rain then scattered snow showers; little to no accumulation
Worcester, MA- Freezing rain .1in accumulation then rain followed by snow squalls 1-3in possible
Boston, MA- Rain followed by scattered snow showers; little to no accumulation
Nantucket, MA- Heavy rain and gale force winds
Hyannis, MA- Heavy rain and gale force winds
Burlington, VT- Wintry mix followed by rain and then heavy snow squalls; 3-6in of snow accumulation
Portland, ME- Wintry mix then rain followed by scattered snow squalls; 1-2in possible
Bangor, ME- Wintry mix followed by heavy snow squalls; 3-6in possible
"Subject to Change"
Current Northeast Snow Depth and Northeast Wind chills...
(Courtesy of Wunderground)
The only model inconsistencies remain for the upper level low forecast position and the intensity of the vortex responsible for snow squall activity with the arctic frontal passage. The exact position and track will be critical to the snowfall max accumulations track. GFS tends to maintain the best dynamics across northern Pennsylvania and western New York State while the NAM and other guidance suggest a more sustained band of rain/snow moving across the entire northeast. Current boundary layer progs by high resolution guidance indicate temperatures above freezing for the majority of the QPF suggesting limited snow accumulations east of the Alleghany Front. Skewt charts also indicate the strongest winds will remain around 925-950mb and will likely only mix to the surface during an energy momentum transfer during the frontal passage. ECMWF guidance is even weaker with the ULL with minimal snow accumulations for all areas generally below advisory criteria. Lake effect snow shower activity will increase by Friday. NAM simulated radar shows several longer bands stretching east of the mountains in New York State and Pennsylvania, but exact location remains uncertain until we get closer to the event. Total SREF QPF for lake effect snows are generally .4in or less. This is due to the unorganized activity with a multi band setup.
After the Storm
As to be expected given this winter's track record, guidance and global teleconnections are no longer supporting a sustained pattern change. Recent ECMWF weeklies and NAEFS prognostics indicate a brief cold period this weekend followed by increasing anomalies towards weeks 2 and 3. It still appears earlier indications of a gradient pattern are likely, but the recent retreat in the expected -NAO appears to have lifted the thermal gradient farther north. This will allow for a more amplified southeast ridge with warmer temperatures reaching farther north locations. Current teleconnections look terrible for a sustained pattern change with a +NAO, -PNA, and questionable MJO phase change. While the pattern will become more stormy, long range guidance suggests very mild weather in the 2-3 week period. ECMWF weeklies were near +5F for the northern Middle Atlantic. Any colder weather will remain across Canada and towards Alaska. There will likely be some sort of snow accumulation before the end of the month for all locations, but east coast cyclogenesis remains unlikely. Towards February a few wavelengths show a return to brief colder weather early in the month, but given the state of the increasing solar activity and madden jullian monsoonal patterns, this remains questionable. Wavelengths suggest stormy periods towards the 16th and 21st of January, but rain vs snow will be a problem through the entire Northeast.
Please post storm reports in this blog from across the Northeast during the winter storm and please post location of observation in each report...
This blog is in progress. Check back soon...
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Lower Susquehanna Valley Doppler...
(Courtesy of WGAL)
"10mi northeast of Harrisburg 2011-2012 winter statistics"
Current Snow Cover- 0.0in
Monthly Total (October)- 5.5in
Monthly Total (November)- 0.0in
Monthly Total (December)- 0.4in
Monthly Total- (January)- 0.2in
Seasonal Total- 6.1in
Winter Weather Advisories- 1
Winter Storm Warnings- 1
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 0
Winter Storm Watches- 1
Lowest High Temperature- 29F
Lowest Low Temperature- 10F
Wind Chill Advisories- 0
Wind Chill Warnings- 0
(Snow Storms Stats)
Historic October Nor'easter - October 29 - 5.5in of wet snow
322 Lake Effect Snow Band - December 17 - 0.3in of wet snow
Weak Clipper - December 29 - 0.1in of snow
322 Lake Effect Snow Band - January 18 - 0.2in of snow