Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS11 KWBC 142206
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
506 PM EST TUE FEB 14 2017

VALID 00Z WED FEB 15 2017 - 00Z SAT FEB 18 2017


NORTHEAST/NEW ENGLAND...

SLIGHT DIFFERENCES IN TIMING AND STRENGTH REMAIN WITH THE CLOSED
LOW CROSSING NEW ENGLAND WEDNESDAY AND THEIR ACCOMPANYING TRANSFER
OF THE INLAND LOW TO A DEEPER LOW IN THE GULF OF MAINE WEDNESDAY
NIGHT/EARLY THURSDAY.  OUR DECISION TO PUT LESS WEIGHT ON THE GFS
SOLN RATHER THAN THE ECMWF/UKMET/SREF/NAM HAD LESS TO DO WITH THE
DIFFERENCES IN POSITION OF THE LOW OR THE TROUGH ALOFT SINCE THE
DIFFERENCES WERE PRETTY SMALL...BUT WERE BASED ON THE ORIENTATION
OF THE PCPN ACROSS THE NORTHEAST.

CONCERNING THE PROBABILITIES...MODERATE PROBABILITIES OF 12 INCHES
AND HIGH PROBABILITIES OF 8 INCHES WERE STILL DEPICTED ACROSS
PARTS OF NH/VT INTO ME WITH LESSER AMOUNTS EXTENDING BACK INTO
UPSTATE NY AND AS SOUTH AS  DEPICTED ACROSS EASTERN NEW HAMPSHIRE
AND SOUTHWEST MAINE WEDNESDAY INTO WEDNESDAY NIGHT...WITH HIGH
PROBABILITIES OF 4 INCHES DOWNWIND OF LAKES ERIE AND ONTARIO.

THE MAJORITY OF SREF ARW CORE MEMBERS WERE FURTHER INLAND WITH THE
COASTAL LOW...RESULTING IN A NORTHWESTWARD SHIFT TO THEIR SNOW
AXES...COMPARED TO THE SREF NMMB/GEFS/ECMWF ENSEMBLES WHICH WERE
REASONABLY WELL-CLUSTERED SOUTHWESTWARD WHERE THE DETERMINISTIC
WWD AMOUNTS SHOW THE HIGHEST AMOUNTS. GIVEN THE REMAINING MODEL
SPREAD...CONFIDENCE IS ONLY AVERAGE FOR THIS EVENT.

THE PROBABILITY OF 0.25 INCHES OF ICE IS LESS THAN 10 PERCENT.

NORTHWEST/CALIFORNIA/N. ROCKIES...

THERE IS A CONTINUED 10 TO 40 PERCENT CHANCE OF 0.25 INCHES OR
MORE OF ICE ACROSS INTERIOR WASHINGTON FROM LATE TUESDAY NIGHT
WHICH CONTINUES THROUGH WEDNESDAY AND INTO EARLY THURSDAY.   WE
CONTINUED TO PUT LESS FAITH IN THE SREF NMMB MEMBERS AND MORE
CONSIDERATION ON A CONSENSUS OF THE LIGHTER SREF ARW CORE
MEMBERS...AS WELL AS THE GEFS/ECMWF AND THEIR RESPECTIVE ENSEMBLE
MEMBERS WITH AVERAGE TO SOMEWHAT ABOVE AVERAGE CONFIDENCE.


CENTRAL-SOUTHERN APPALACHIANS...

THE MODELS STILL DEPICT SOME LIGHT SNOW IN PORTIONS OF THE UPSLOPE
REGION IN THE CENTRAL/SOUTHERN APPALACHIANS.  SNOWFALL AMOUNTS
DERIVED FROM THE WPC QPF AND VARIOUS SNOW TO LIQUID AMOUNTS WERE
GENERALLY ON THE ORDER OF AN INCH OR TWO...ALTHOUGH THERE WERE
ENOUGH ENSEMBLE MEMBERS TO SUPPORT A SLIGHT RISK OF 4 INCHES.

THE PROBABILITY OF 0.25 INCHES OF ICE IS LESS THAN 10 PERCENT.

BANN


$$





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