Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 070831
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
331 AM EST SUN FEB 07 2016

VALID 12Z SUN FEB 07 2016 - 12Z WED FEB 10 2016


UPPER MISSISSIPPI VALLEY/UPPER
MIDWEST/CAROLINAS/MID-ATLANTIC/NORTHEAST/APPALACHIANS...

THE COMPLEX EVOLUTION OF A MAJOR CYCLONE OFF THE SOUTHEAST
COAST...A LARGE REGION OF UPPER CONFLUENCE OVER NEW ENGLAND
FOLLOWING THE PASSAGE OF A SHORTWAVE TROUGH OFF EASTERN CANADA ON
MONDAY...AND THE AMPLIFICATION OF A LARGE SCALE UPPER TROUGH OVER
THE EASTERN UNITED STATES CHARACTERIZED BY SEVERAL EMBEDDED
SHORTWAVE SYSTEMS LEAVES A COMPLICATED SNOWFALL FORECAST FOR ALL 3
DAYS FROM THE SOUTHEAST US ACROSS THE MIDDLE ATLANTIC STATES AND
NEW ENGLAND. IN ADDITION...THERE MAY ALSO BE BOUNDARY LAYER
TEMPERATURE ISSUES THAT ALSO COMPLICATE THE SNOWFALL FORECAST.
THERE APPEAR TO BE SEVERAL DISJOINTED AREAS OF SNOWFALL THAT ARE
NOT CONSISTENTLY FORECAST FROM ONE MODELING SYSTEM TO MODELING
SYSTEM.  ALL IN ALL...THIS IS A LOW CONFIDENCE FORECAST.

IN THIS KIND OF FORECAST DILEMMA WITH WIDELY VARYING
SOLUTIONS...PERHAPS A GOOD STRATEGY GOING IN IS TO BE RELATIVELY
CONSERVATIVE ON AMOUNTS AND USING THE ENSEMBLE MEANS/SPREAD AS A
GUIDE WITH WHICH TO SELECT PARTS OF SOME OPERATIONAL FORECASTS
THAT SEEM TO MATCH TO SOME DEGREE THE MEAN SOLUTIONS.  THIS OF
COURSE STILL ALLOWS SOME OF THE SOLUTIONS THAT APPEAR TO BE
POSSIBLE BUT HAVE LOWER PROBABILITIES THAN OTHER SOLUTIONS.  FOR
EXAMPLE...THE NAM/SREF SOLUTIONS FOR BRINGING SNOW NORTHWARD ALONG
THE MIDDLE ATLANTIC STATES INTO SOUTHERN NEW ENGLAND ON DAYS 1
INTO 2 MAY APPEAR TO BE AN OUTLIER SOLUTION WITH RESPECT TO SOME
OTHER MODELS...BUT CANNOT BE TOTALLY DISCOUNTED SINCE THEY STILL
REPRESENT A PORTION OF THE POSSIBLE SOLUTIONS.

ON DAY 1/SUNDAY THROUGH MONDAY MORNING...A DEEP CYCLONE WILL MOVE
NORTHEASTWARD OFF THE SOUTHEAST COAST WITH A SMALL PROBABILITY OF
SNOW MIXING WITH RAIN...WITH ONLY A VERY LOW PROBABILITY THAT SOME
REGION ACROSS INTERIOR SOUTH CAROLINA INTO EASTERN NORTH CAROLINA
WILL PICK UP MEASURABLE SNOW...LET ALONE SIGNIFICANT SNOW GREATER
THAN 4 INCHES. FARTHER TO THE NORTH...AN AMPLIFYING SHORTWAVE
ROUGH OVER THE UPPER MISSISSIPPI VALLEY AND UPPER MIDWEST WILL
BRING A LOW TO PERHAPS MODERATE RISK OF GREATER THAN 4 INCHES OF
SNOW PRIMARILY ACROSS THE UPPER PENINSULA OF MICHIGAN WITH ONLY A
LOW RISK ACROSS NORTHERN MINNESOTA.

BY DAY 2/MONDAY THROUGH TUESDAY MORNING...THERE REMAINS A LOW TO
MODERATE RISK OF GREATER THAN 4 INCHES OF SNOW ACROSS THE UPPER
PENINSULA OF MICHIGAN WHILE ONLY LIGHT SNOW IS POSSIBLE ACROSS THE
OHIO VALLEY.  MORE SIGNIFICANT SNOW IS EXPECTED TO DEVELOP ALONG
THE APPALACHIANS WHERE THERE IS A LIKELIHOOD OF GREATER THAN 4
INCHES FROM THE MOUNTAINS OF NORTH CAROLINA NORTHWARD INTO
SOUTHWESTERN PENNSYLVANIA. A LOW PROBABILITY OF GREATER THAN 4
INCHES EXTENDS NORTH AND EASTWARD ACROSS SOUTH CENTRAL
PENNSYLVANIA AND NORTHERN MARYLAND.  ANOTHER AREA WHERE THERE IS
LOW TO MODERATE PROBABILITY OF GREATER THAN 4 INCHES IS LOCATED
ALONG THE EASTERN NEW ENGLAND COASTLINE...WHERE OCEAN EFFECT SNOW
ON NORTHEASTERLY WINDS HAS THE POTENTIAL TO PRODUCE LOCALLY HEAVY
SNOW ACROSS SOUTHEASTERN MASSACHUSETTS.

BY DAY 3/TUESDAY INTO WEDNESDAY MORNING...THERE IS ONLY A LOW
PROBABILITY OF GREATER THAN 4 INCHES OF SNOW ACROSS PORTIONS OF
THE APPALACHIANS AND THE MIDDLE ATLANTIC STATES AS ANOTHER
SHORTWAVE PASSES ACROSS THE MIDDLE ATLANTIC STATES.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

KOCIN


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