Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 140926
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
425 AM EST SUN DEC 14 2014

VALID 12Z SUN DEC 14 2014 - 12Z WED DEC 17 2014


DAYS 1-3...

...NORTHERN-CENTRAL ROCKIES/CENTRAL PLAINS/UPPER MIDWEST...

MODELS ARE IN GOOD AGREEMENT SHOWING A MID/UPPER LEVEL CENTER
CLOSING OFF WITHIN A WELL-DEFINED NEGATIVELY TILTED TROUGH LIFTING
OUT OF THE SOUTHWEST INTO THE SOUTHERN HIGH PLAINS EARLY SUN.
THIS SYSTEM IS FORECAST TO CONTINUE LIFTING THE
NORTHEAST...REACHING THE LOWER MO/MID MS VALLEY EARLY MON.  BY
LATE MON-EARLY TUE THE LOW IS EXPECTED TO GRADUALLY WEAKEN AS IT
REACHES THE GREAT LAKES REGION AND BEGINS TO INTERACT WITH AN
AMPLIFIED TROUGH DROPPING OUT OF CANADA INTO THE UPPER MIDWEST.
ON DAY 1 (EARLY SUN-EARLY MON)...AS THE UPPER LOW MOVES OUT INTO
THE PLAINS...MODELS SHOW MODERATE TO HEAVY PRECIPITATION
DEVELOPING IN THE ASSOCIATED DEFORMATION ZONE ACROSS THE CENTRAL
HIGH PLAINS...RESULTING IN SOME POTENTIALLY HEAVY SNOWS OF UP TO A
FOOT ACROSS PORTIONS OF WESTERN NEB AND NORTHEASTERN CO.
MEANWHILE...VIGOROUS NORTHERLY FLOW IN THE WAKE OF A NORTHERN
STREAM COLD FRONT WILL PROMOTE GENERALLY LIGHTER AMOUNTS FURTHER
TO THE WEST BACK ACROSS THE ROCKIES OF CENTRAL CO/WY.  ON DAY 2
(EARLY MON-EARLY TUE)...DEFORMATION PRECIPITATION IS EXPECTED TO
LIFT FROM NORTHERN NEB..SOUTHERN-CENTRAL SD INTO MN AND THE UPPER
GREAT LAKES REGION.  SURFACE COLD AIR SINKING IN FROM THE NORTH
UNDERCUTTING A STRONG INTRUSION OF WARM AIR ALOFT IS EXPECTED TO
PRODUCE AN ICY TRANSITION ZONE FROM NORTHEASTERN NEB/SOUTHEASTERN
SD TO NORTHWESTERN WISC AND THE WESTERN U.P. WHILE LIMITING THE
POTENTIAL FOR WIDESPREAD HEAVY SNOW ACCUMULATIONS ACROSS THIS
REGION.

...SOUTHERN OREGON/NORTHERN CALIFORNIA...

THE HEAVY SNOW THREAT IS EXPECTED TO RETURN TO THE
REGION...ESPECIALLY TO THE SOUTHERN CASCADES...KLAMATH...AND
NORTHERN-CENTRAL SIERRA AS A PAIR OF SHORTWAVES EMBEDDED WITH A
BROADER..EASTERLY PROGRESSING UPPER TROUGH IMPACT THE REGION.  THE
FIRST SHORTWAVE IS EXPECTED TO SWING ACROSS THE REGION LATE
MON-EARLY TUE WITH SNOW LEVELS DECREASING TO AROUND 3500-4500 FT
IN MOST AREAS.  THE SECOND SYSTEM IS EXPECTED TO REACH THE AREA
TUE NIGHT...PRODUCING ADDITIONAL ROUNDS OF PRECIPITATION...WITH
SNOW LEVELS AGAIN REMAINING BETWEEN 3500-4500 FT IN MOST AREAS.
MOISTURE WITH THESE SYSTEMS IS NOT EXPECTED TO BE NEARLY AS
IMPRESSIVE AS THAT ASSOCIATED WITH THE PREVIOUS STORM...LIMITING
THE POTENTIAL FOR WIDESPREAD ACCUMULATIONS EXCEEDING A FOOT.

PEREIRA

$$





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