Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 122157
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
456 PM EST THU JAN 12 2017

VALID 00Z FRI JAN 13 2017 - 00Z MON JAN 16 2017


...CENTRAL GREAT BASIN TO SOUTHERN/CENTRAL ROCKIES...

AN ANOMALOUS UPPER LOW DROPPING SOUTHEASTWARD OFF THE CALIFORNIA
COAST WILL BRING MODERATE TO HEAVY SNOW OVER THE HIGHER ELEVATIONS
OF THE CENTRAL GREAT BASIN AND COLORADO ROCKIES THURSDAY INTO
FRIDAY...WITH THE CHANCE FOR SNOW SHIFTING SOUTH AND EAST INTO THE
SOUTHERN ROCKIES AS THE UPPER LOW CROSSES NORTHERN MEXICO THIS
WEEKEND.  WPC PROBABILISTIC GUIDANCE KEEPS THE HIGHEST
PROBABILITIES OF SNOWFALL ACCUMULATIONS EXCEEDING A FOOT OVER THE
SAN JUAN MOUNTAINS OF SOUTHWEST COLORADO.


...SOUTHERN/CENTRAL PLAINS TO THE MIDDLE MISSISSIPPI VALLEY...OHIO
VALLEY...AND MID-ATLANTIC STATES...

A WIDESPREAD ICING EVENT IS SETTING UP FROM THE SOUTHERN/CENTRAL
PLAINS TO MIDDLE MISSISSIPPI VALLEY...OHIO VALLEY...AND
MID-ATLANTIC STATES OVER THE NEXT SEVERAL DAYS...WITH POTENTIALLY
SIGNIFICANT AND HIGH-IMPACT ICE ACCUMULATIONS CENTERING OVER
OKLAHOMA...KANSAS...AND MISSOURI.

A FRONTAL BOUNDARY STALLED FROM THE SOUTHERN PLAINS TO THE
MID-ATLANTIC STATES WILL INITIALLY SET THE STAGE FOR THE
EVENT...WHERE THE COMBINATION OF ARCTIC HIGH PRESSURE TO THE NORTH
OF THE BOUNDARY AND AN UPPER RIDGE BUILDING OVER THE SOUTHEASTERN
U.S. WILL LEAD TO FREEZING RAIN WITHIN THE NORTHERN EDGE OF
PRECIPITATION DEVELOPING ALONG THE BOUNDARY ON FRIDAY.
PRECIPITATION...AND THE THREAT FOR ACCUMULATING ICE...WILL REALLY
ENHANCE ACROSS PORTIONS OF THE SOUTHERN/CENTRAL PLAINS AND MIDDLE
MISSISSIPPI VALLEY AS MOISTURE AND INSTABILITY INCREASE AHEAD OF
AN UPPER LOW PIVOTING NORTHEASTWARD OUT OF NORTHERN MEXICO THIS
WEEKEND.

MODELS CONTINUE TO SHOW A STRONG SIGNAL FOR HAZARDOUS ICE
ACCUMULATIONS EXTENDING FROM NORTHERN OKLAHOMA THROUGH KANSAS AND
INTO MISSOURI...BUT THEY ARE STILL VARYING WITH THE EXACT LOCATION
AND TOTALS.  BESIDES MODEL MASS FIELD DIFFERENCES DISCUSSED IN
WPC`S MODEL DIAGNOSTIC DISCUSSION (PMDHMD)...MODELS ARE ALSO
SHOWING A SIGNIFICANT AMOUNT OF SPREAD WITH THERMAL PROFILES
ACROSS THE PLAINS/MIDDLE MISSISSIPPI VALLEY THROUGHOUT THE EVENT.
IN GENERAL...THE GFS REPRESENTED THE WARMER SIDE OF MODEL SPREAD
WITH THE MAGNITUDE OF THE LOW-LEVEL COLD AIR...WHILE THE NAM
OFFERED ONE OF THE COLDER SOLUTIONS.

THE LATEST WPC PROBABILISTIC GUIDANCE HAS A MODERATE RISK (AT
LEAST A 40% PROBABILITY) OF ICE ACCUMULATIONS EXCEEDING 0.25" OVER
PORTIONS OF THE PLAINS/MIDDLE MISSISSIPPI VALLEY FOR ALL THREE
DAYS OF THE FORECAST...WITH A HIGH RISK (AT LEAST 70% PROBABILITY)
OF ICE ACCUMULATIONS EXCEEDING 0.25" DURING THE DAY 2 AND 3
FORECAST.  ALSO..THERE IS A SLIGHT RISK(AT LEAST A 10%
PROBABILITY) OF ICE ACCUMULATIONS EXCEEDING .25" OVER WEST
VIRGINIA DURING THE DAY 2 FORECAST.


GERHARDT

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