Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 282048
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
447 PM EDT FRI APR 28 2017

VALID 00Z SAT APR 29 2017 - 00Z TUE MAY 02 2017

...CENTRAL/SOUTHERN ROCKIES TO THE CENTRAL PLAINS AND UPPER
MISSISSIPPI VALLEY...

A LATE SEASON SNOW EVENT THAT DUMPED OVER A FOOT OF SNOW IN
WYOMING AND BROUGHT ACCUMULATING SNOW TO WESTERN NEBRASKA ON
FRIDAY WILL IMPACT LOCATIONS FROM THE CENTRAL/SOUTHERN ROCKIES TO
THE CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY THIS WEEKEND.

THE HEAVIEST SNOW AND HIGHEST ACCUMULATIONS WITH THIS EVENT SHOULD
BE OVER THE TERRAIN OF COLORADO AND NEW MEXICO AS AN AMPLIFYING
UPPER TROUGH CLOSES OFF OVER THE FOUR CORNERS REGION FRIDAY NIGHT
INTO SATURDAY.  THE COMBINATION OF BELOW NORMAL TEMPERATURES WITH
THE ANOMALOUS UPPER TROUGH AND INCREASING MOIST LOW LEVEL
EASTERLY/NORTHEASTERLY FLOW BEHIND A COLD FRONT DROPPING THROUGH
THE HIGH PLAINS WILL SUPPORT PERIODS OF HEAVY SNOW OVER THE
WINDWARD TERRAIN...ESPECIALLY FROM THE NORTH CENTRAL COLORADO
ROCKIES TO THE SANGRE DE CRISTO MOUNTAINS.  ALSO...POST-FRONTAL
COLD ADVECTION SHOULD CHANGE RAIN OVER TO SNOW IN THE ADJACENT
HIGH PLAINS AND ALLOW FOR ACCUMULATING SNOW TO SPREAD OUT INTO
PORTIONS OF EASTERN COLORADO AND NORTHEASTERN NEW MEXICO.

AS THE CLOSED LOW GRADUALLY EDGES EASTWARD TOWARDS THE SOUTHERN
PLAINS ON SATURDAY AND AN AREA OF LOW PRESSURE DEEPENS OVER
TEXAS...THE CHANCE FOR SNOW WILL SHIFT TO THE NORTHWESTERN FRINGE
OF PRECIPITATION DEVELOPING WITHIN A STRENGTHENING DEFORMATION
ZONE.  HOWEVER...MODEL GUIDANCE REMAINS EXTREMELY UNCERTAIN WITH
LOW LEVEL THERMAL PROFILES AND HOW MUCH SNOW CAN
ACCUMULATE...ESPECIALLY AS THE CLOSED LOW TAKES ON A NEGATIVE TILT
WHILE PIVOTING NORTHEASTWARD THROUGH THE MIDDLE AND UPPER
MISSISSIPPI VALLEY SUNDAY AND MONDAY.  THE NAM CONTINUES TO BE ON
THE COLDER SIDE OF MODEL SPREAD AND HIGHEST WITH SNOWFALL
ACCUMULATIONS WHILE THE ECMWF CONTINUES TO REPRESENT THE WARMER
SIDE OF MODEL SPREAD.  PLEASE REFER TO THE MODEL DIAGNOSTIC
DISCUSSION (PMDHMD) FOR MORE DETAILS ON MODEL DIFFERENCES WITH
THIS SYSTEM.  DESPITE THE UNCERTAINTY WITH ACCUMULATIONS WITHIN
THE DEVELOPING DEFORMATION ZONE...THE LATEST WPC PROBABILISTIC
GUIDANCE IS ADVERTISING A DAY 2 MODERATE RISK (AT LEAST 40%
PROBABILITY) OF SNOWFALL EXCEEDING 4 INCHES FROM SOUTHEASTERN
COLORADO INTO WESTERN KANSAS AND SOUTHERN NEBRASKA AND DAY 3
MODERATE RISK AREAS OF SNOWFALL EXCEEDING 4 INCHES OVER PORTIONS
OF EXTREME EASTERN SOUTH DAKOTA AND MINNESOTA.


THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.


GERHARDT

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