Quantitative Precipitation Forecast
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FOUS11 KWBC 090758
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
257 AM EST TUE FEB 09 2016

VALID 12Z TUE FEB 09 2016 - 12Z FRI FEB 12 2016


DAYS 1 THROUGH 3...

...GREAT LAKES...

A DEEP UPPER TROUGH WILL DOMINATE THE FLOW ACROSS THE GREAT LAKES
STATES WITH INCREASINGLY COLDER AIR AND RELATIVELY ICE FREE WATER
WILL KEEP THE THREAT FOR LAKE EFFECT SNOW QUITE ALIVE ON ALL 3
DAYS.  A DEEP UPPER LOW OVER THE MIDWEST ON DAY 1/TUESDAY WILL
LIFT NORTHEASTWARD WHILE A SECONDARY SHORTWAVE TROUGH WILL
REINFORCE THE UPPER TROUGH ON WEDNESDAY/DAY 2.  THIS TROUGH WILL
BEGIN TO LIFT NORTHEASTWARD ACROSS THE NORTHEAST ON THURSDAY/DAY 3
AS A VERY COLD SURGE OF ARCTIC/POLAR AIR BEGINS TO SURGE SOUTHWARD
ACROSS SOUTH CENTRAL CANADA.

MOSTLY LIGHT TO MODERATE SNOW IS EXPECTED DOWNWIND OF THE GREAT
LAKES ON DAYS 1/2 AND 3 WITH SOME MODERATE TO HIGH CHANCES OF
GREATER THAN 4 INCHES OF SNOW DOWNWIND OF LAKES SUPERIOR/MICHIGAN
AND HURON ON DAY 1...EXPANDING TO INCLUDE THE AREAS DOWNWIND OF
LAKES ERIE AND ONTARIO ON DAY 2 AND ONLY MORE LOCALIZED THREATS ON
DAY 3/THURSDAY...MOSTLY EAST AND SOUTHEAST OF LAKE ONTARIO IN NEW
YORK.

DAYS 1 TO 2...

...EASTERN OHIO VALLEY/APPALACHIANS/MIDDLE ATLANTIC/NEW ENGLAND...

SOME RESIDUAL LIGHT SNOW FROM THE ATLANTIC STORM IS EXPECTED TO
PRODUCE NO MORE THAN A COUPLE INCHES OF SNOW ACROSS CENTRAL AND
NORTHERN MAINE ON DAY 1/TUESDAY.  A SERIES OF EMBEDDED IMPULSES
WITHIN THE DEEP CYCLONIC FLOW ACROSS THE EASTERN US WILL BRING
SOME SCATTERED SNOW ACROSS THE EASTERN OHIO VALLEY/APPALACHIANS
INTO THE MIDDLE ATLANTIC REGION AND POSSIBLY BACK ACROSS SOUTHERN
NEW ENGLAND ON WEDNESDAY.

THERE STILL REMAIN QUITE A LOT OF SIGNIFICANT DIFFERENCES AMONG
SOLUTIONS ALTHOUGH THERE HAS CERTAINLY BEEN MORE CLUSTERING WITH
WHERE SOME OF THE MORE SIGNIFICANT SNOWFALL CAN BE EXPECTED.  THE
COMBINATION OF THE FIRST SHORTWAVE WILL PRODUCE A MODEST CYCLONE
DEVELOPING OFF THE MIDDLE ATLANTIC COAST ON TUESDAY THAT WILL
PROGRESS EAST NORTHEASTWARD OUT OVER THE OPEN ATLANTIC.
HOWEVER...A SECOND IMPULSE APPEARS TO HAVE SHIFTED SLIGHTLY
NORTHWARD OVER THE PREVIOUS SERIES OF FORECASTS THAT MAY BE
BRINGING THE POTENTIAL OF SIGNIFICANT SNOW SLIGHTLY FARTHER
NORTH...WHILE DIMINISHING THE THREAT OF SNOW FARTHER SOUTH.  FOR
EXAMPLE MOST OF VIRGINIA WILL ESCAPE SIGNIFICANT SNOW AS MILD
TEMPERATURES ULTIMATELY COOL ON TUESDAY BUT ONLY A FEW MODELS
STILL PUT QPF AMOUNTS EXCEEDING .25 INCHES OVER NORTHERN VIRGINIA.


THE GREATEST THREAT OF SIGNIFICANT SNOW APPEARS TO HAVE EDGED
NORTHWARD ACROSS EXTREME NORTHERN MARYLAND AND INTO SOUTH CENTRAL
TO SOUTHEASTERN PENNSYLVANIA INTO NEW JERSEY...WHERE TEMPERATURES
ARE ALREADY RIPE FOR SNOWFALL ACCUMULATIONS.  SOME FORECASTS EVEN
EXTEND THE SNOWFALL SLIGHTLY FARTHER NORTHWARD ACROSS NORTH
CENTRAL AND NORTHEAST PENNSYLVANIA INTO NORTHERN NEW JERSEY/NEW
YORK CITY/ISLAND AND POSSIBLY EVEN ACROSS EXTREME SOUTHERN NEW
ENGLAND LATE ON TUESDAY INTO EARLY WEDNESDAY.  SOME OF THE
OPERATIONAL AND HIGHER RESOLUTION RUNS, INCLUDING THE 00Z HI RES
GFS/00Z NAM/CANADIAN/UKMET/NAMCONEST/ARW AND NMM ALL SEEM TO POINT
THIS WAY.  ITS ONLY A SLIGHT SHIFT BUT POSSIBLY REDUCES THREAT IN
AND AROUND DC AND INCREASES IT IN NYC.  THERE IS ONLY A LOW TO
MODERATE PROBABILITY OF GREATER THAN 4 INCHES OF SNOW. FARTHER
WEST...THERE ARE STILL FAVORABLE CONDITIONS FOR UPSLOPE ENHANCED
SNOW ACROSS THE APPALACHIANS...ESPECIALLY ACROSS EASTERN WEST
VIRGINIA/WESTERN MARYLAND AND SOUTHWESTERN PENNSYLVANIA...WHERE
TWO DAY TOTALS SHOULD APPROACH 4 TO 8 INCHES WITH RELATIVELY HIGH
PREDICTABILITY.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

KOCIN

$$




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