Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 062108
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
408 PM EST SAT FEB 06 2016

VALID 00Z SUN FEB 07 2016 - 00Z WED FEB 10 2016

UPPER MIDWEST...

THE ENSEMBLE MEMBER SPREAD IS FAIRLY EVENLY DISTRIBUTED FOR LOW
AND MODERATE PROBABILITIES OF 4 INCHES OF SNOW FROM NEAR THE NORTH
DAKOTA/MINNESOTA BORDER ACROSS THE UPPER PENINSULA OF MICHIGAN FOR
TONIGHT THROUGH MONDAY AS THE LOW TRACKS THROUGH THE REGION.
CONFIDENCE IS ALSO MODEST GIVEN THE REDUCED SPREAD AND SLOWING
TRENDS TOWARD THE NORTH.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

CAROLINAS/MID-ATLANTIC/NORTHEAST/APPALACHIANS...

THE PROBABILITIES FOR 4/8/12 INCHES OF SNOW WERE MODIFIED
CONSIDERABLY FROM THEIR AUTOMATED GENERATION TO SKEW THE
PROBABILITIES TOWARD AN INTERMEDIATE OUTCOME INVOLVING THE 06-12Z
GEFS MEAN AND 00Z ECMWF ENSEMBLE MEAN FOR THE COMPLICATED REGIME
UNFOLDING ALONG THE EAST FROM TONIGHT THROUGH MONDAY. BEGINNING
TONIGHT AND SUNDAY...MANY SREF MEMBERS ARE VERY HEAVY WITH SNOW
DEVELOPING OVER THE EASTERN CAROLINAS WITH THEIR SOLUTIONS
CONSIDERED HIGHLY UNLIKELY. THE SREF ALSO APPEAR TO BIAS THE
PROBABILITIES FOR 4 AND 8 INCHES OF SNOW EXTENDING ALONG THE
MID-ATLANTIC AND NORTHEAST COASTS SUNDAY NIGHT INTO MONDAY WITH
THE FINAL NUMBERS ALSO MODIFIED AND/OR ELIMINATED IN SOME AREAS.
BY MONDAY NIGHT AND TUESDAY...THE SOLUTION SPREAD CONCERNING THE
LOCATION AND TIMING OF THE TROWEL DEVELOPING OVER THE MID-ATLANTIC
REMAINS QUITE HIGH...WITH CONSIDERABLY IMPACT DIFFERENCES. THE
DETERMINISTIC SOLUTION SPREAD IS COMPARABLE AND REPRESENTATIVE OF
THE ENSEMBLE SPREAD...WITH THE 12Z GFS ON THE NORTHERN SIDE OF THE
GUIDANCE...THE 12Z ECMWF ON THE SOUTHERN SIDE...AND 12Z NAM NEAR
THE MIDDLE. GIVEN THE RUN-TO-RUN VARIABILITY OF DIFFERING DETAILS
FROM THE GUIDANCE...HAVE CHOSEN TO REMAIN CLOSE TO THE CONSENSUS
WITH UNUSUALLY LOW CONFIDENCE. GIVEN THE AGREEING NATURE OF THE
ENSEMBLE SPREAD WITH THE DETERMINISTIC SPREAD BY DAY 3...THE
AUTOMATED PROBABILITIES WERE ACTUALLY EDITED LESS COMPARED TO DAYS
2 AND 3 AS THE SREF APPEARS MORE REASONABLE PERHAPS MORE SO OUT OF
COINCIDENCE...ALTHOUGH THEY MAY STILL BE TOO HIGH ACROSS NORTHERN
MAINE...SO THE VALUES WERE TONED DOWN SLIGHTLY.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

JAMES


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