Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center

 
 

 

Follow the Weather Prediction Center on Facebook Follow the Weather Prediction Center on Twitter
NCEP Quarterly Newsletter
WPC Home
Analyses and Forecasts
   National High & Low
   WPC Discussions
   Surface Analysis
   Days ½-2½ CONUS
   Days 3-7 CONUS
   Days 4-8 Alaska
   QPF
   PQPF
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/
Warnings

Satellite and Radar Imagery
   Satellite Images
   National Radar
Product Archive
WPC Verification
   QPF
   Medium Range
   Model Diagnostics
   Event Reviews
   Winter Weather
International Desks
Development and Training
   Development
WPC Overview
   About the WPC
   Staff
   WPC History
   Accomplishments
   Other Sites
   FAQs
Meteorological Calculators
Contact Us
   About Our Site
 
USA.gov is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
 
Winter Weather Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 2032Z Nov 20, 2017)
 
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
 
Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
332 PM EST MON NOV 20 2017

VALID 00Z TUE NOV 21 2017 - 00Z FRI NOV 24 2017


DAYS 1-3...

...PACIFIC NORTHWEST TO FRONT RANGE OF ROCKIES...

A SHORT WAVE MOVING AND DECAYING THROUGH THE PACIFIC NORTHWEST
THIS AFTERNOON WILL SHEAR-OUT DOWN THE FRONT RANGE OF THE
NORTHERN/CENTRAL ROCKIES. THIS WILL RESULT IN HEAVY MTN SNOW FROM
NWRN MT AND CENTRAL ID INTO PARTS OF THE WESTERN WY TERRAIN AND
BIG HORN MTNS TO THE NORTHERN CO ROCKIES WITH LIGHT OVERRUNNING
ACCUMULATIONS EAST OF THE TERRAIN FROM CENTRAL MT TO NERN WY. AS
THIS SYSTEM DEPARTS THE WEST, A BUILDING UPPER RIDGE OF HIGH
PRESSURE WILL SLIDE IN FOR WED. HOWEVER, ANOTHER SET OF HEIGHT
FALLS FROM THE NERN PAC WILL MOVE INTO WA/OR AND ENOUGH MOISTURE
TRANSPORT WITH THIS SYSTEM MAY YIELD SOME SNOW ACROSS THE WA
CASCADES.

...EASTERN GREAT LAKES AND NORTHERN NEW ENGLAND...

A DYNAMIC SHORT WAVE JUST NORTH OF THE UPPER MIDWEST US/CANADIAN
BORDER WILL ROLL DOWNSTREAM THROUGH ONTARIO OVER THE NEXT 24 HRS.
THIS POLAR SYSTEM WILL BE FOLLOWED UP BY ADDITIONAL UPSTREAM UPPER
DYNAMICS THAT REACH THE BASE OF THE UPPER TROUGH AND ALLOW A
WELL-DEFINED COLD FRONT TO SWEEP THROUGH THE EASTERN LAKES AND
NERN QUAD OF THE COUNTRY. THE VIGOROUS UPPER DYNAMICS MAY ALLOW
SOME POST-FRONTAL BUT LIGHT SNOWFALL WITH MINIMAL ACCUMULATIONS
FROM NERN OH/NWRN PA INTO WESTERN AND UPSTATE NY. ALSO, AS THE
COLD FRONT AND UPPER TROUGH SWEEP TO THE NERN SEABOARD, POSSIBLE
PHASING OF UPPER JETS MAY ALLOW SURFACE LOW DEVELOPMENT NEAR
COASTAL MAINE BEFORE LIFTING/DEEPENING UP INTO THE CANADIAN
MARITIMES. THIS MAY PRODUCE  A BURST OF HEAVY SNOWFALL ACROSS THE
WESTERN/NWRN PORTION OF MAINE BEFORE SHIFTING INTO EASTERN QUEBEC.

...UPPER MIDWEST...

A WEAK SHORT WAVE IMPULSE CAUGHT IN THE BROAD LARGE SCALE SWRLY
FLOW ALOFT IN THE PAC WILL ROUND THE BUILDING UPPER WESTERN RIDGE
OVER THE NEXT 24 HRS. THIS SHORT WAVE WILL SLIDE SOUTHEAST FROM
ALBERTA AND REACH THE UPPER MIDWEST ON WED. THIS SHOULD INDUCE A
WEAK SURFACE WAVE AND PRODUCE ENOUGH LIFT AND FORCING FOR WARM
ADVECTION LIGHT FREEZING DRIZZLE INVOF OR JUST NORTH OF THIS WAVE.
A BLEND OF THE GUIDANCE SUGGESTS THE MAIN CORRIDOR OF OF LESS THAN
.05 OF ICE FROM NWRN/NORTHERN ND SOUTH AND EAST TOWARD WEST
CENTRAL MN, WHICH MAY PRODUCE DOME DRIVING HAZARDS.
  

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

MUSHER