Quantitative Precipitation Forecast
Issued by NWS

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
000
FOUS11 KWBC 120713
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
313 AM EDT SAT APR 12 2014

VALID 12Z SAT APR 12 2014 - 12Z TUE APR 15 2014


DAY 1 THROUGH 3

...ROCKY MOUNTAINS/HIGH PLAINS...

MODERATE PROBABILITIES OF 8 INCHES AND LOW PROBABILITIES OF 12
INCHES OR MORE OF SNOW CONTINUE FOR PRIMARILY THE EASTERN FACING
SLOPES OF THE NORTHERN AND CENTRAL ROCKIES AND ACCOMPANYING HIGH
PLAINS BEGINNING TODAY AND CONTINUING SOUTHWARD INTO SUNDAY BEFORE
WANING.  THE LARGE-SCALE UPPER TROUGH RESPONSIBLE FOR THE COLD
FRONTAL PASSAGE AND ASSOCIATED UPSLOPE FLOW HAS GOOD OVERALL
AGREEMENT FROM THE VARIOUS GUIDANCE AND THUS IS DEPICTED WITH
HIGHER THAN USUAL CONFIDENCE...
PARTICULARLY FOR THE LOWER SNOW THRESHOLDS.  THE PRIMARY
CONSIDERATION WITH REGARDS TO SNOW IS THE P-TYPE WITH AN EMPHASIS
PLACED UPON THE MORE AGREEING AND GENERALLY WARMER CLUSTER OF
GUIDANCE FOR DETERMINING SNOW INTO THE HIGH PLAINS...WHICH IS
HEAVILY ECMWF-WEIGHTED WITH ONLY MINOR CONTRIBUTIONS FROM THE SREF
MEAN.  AFTER 12Z...THE NAM/SREF MEAN/GEFS MEAN MOVE TOWARD THE
COLD SIDE OF THE GUIDANCE AND THUS WERE REMOVED FROM P-TYPE
CONSIDERATIONS.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

...UPPER MIDWEST/UPPER GREAT LAKES...

LOW PROBABILITIES OF 4 INCHES OF SNOW ARE DEPICTED ACROSS PORTIONS
OF UPPER MIDWEST AND UPPER GREAT LAKES SATURDAY NIGHT THROUGH
MONDAY IN ASSOCIATION WITH WEAK SURFACE LOWS CROSSING MICHIGAN
SUNDAY AND AGAIN ON MONDAY.  RELIED UPON A MULTI-MODEL CONSENSUS
INVOLVING THE ECMWF/CANADIAN/ECMWF ENSEMBLE MEAN/SREF MEAN FOR
LIQUID EQUIVALENT AMOUNTS...AND AN ECMWF/SREF MEAN/ECMWF ENSEMBLE
MEAN BLEND FOR P-TYPE...WITH LITTLE OR NO NAM AND GEFS MEAN USED
BASED ON THEIR FASTER PROGRESSION AND COLDER THERMAL PROFILES
WHICH IF CORRECT WOULD SUPPORT MUCH MORE SNOW THAN CURRENTLY
DEPICTED.  COLD AIR WILL GRADUALLY ENTRAIN INTO THE REGION NORTH
AND WEST OF THE LOWS HOWEVER...WITH THE MAJORITY OF PRECIPITATION
LIKELY REMAINING IN TEMPERATURE PROFILES LARGELY ABOVE ZERO
DEGREES C.  NEVERTHELESS...ENOUGH ASCENT AND MOISTURE APPEAR TO
COINCIDE WITH MORE FAVORABLE THERMAL PROFILES FOR SNOW TO SUPPORT
LOW PROBABILITIES OF 4 INCHES ACROSS THE REGION.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

...NORTHERN NEW ENGLAND...

ISENTROPIC UPGLIDE ASSOCIATED WITH A RETREATING WARM FRONT WITH
TEMPERATURES SLIGHTLY BELOW FREEZING WITHIN THE COLD SECTOR FAVOR
LOW PROBABILITIES OF 4 INCHES OF SNOW AND 0.25 INCHES OF FREEZING
RAIN FOR SUNDAY INTO SUNDAY NIGHT AS THE WARM FRONT PASSES.  OTHER
THAN THE NAM WHICH LIES NEAR THE HIGH END OF THE GUIDANCE FOR
LIQUID EQUIVALENT AMOUNTS ACROSS NORTHERN MAINE...00Z GUIDANCE
CLUSTERS REASONABLY WELL TO WARRANT EXCLUDING THE NAM.  THE RESULT
IS A NARROW REGION FOR FAVORABLE SNOW AND/OR ICE ACCUMULATIONS
ACROSS THE WHITE MOUNTAINS OF NEW HAMPSHIRE INTO NORTHERN MAINE.

JAMES



$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.