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
   Air Quality
   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
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 0752Z Apr 14, 2014)
 
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
352 AM EDT MON APR 14 2014

VALID 12Z MON APR 14 2014 - 12Z THU APR 17 2014

...OH VALLEY/EASTERN GREAT LAKES/NORTHEAST

A NARROW SWATH OF SNOW WILL ACCOMPANY THE BACK SIDE OF THE RAPIDLY
EXITING LOW CURRENTLY OVER ILLINOIS AS IT REACHES CANADA LATER
TODAY.  MODEL GUIDANCE IS RELATIVELY CLOSE WITH THE PATH AND SPEED
OF THE LOW AND ALSO AGREE THAT TEMPERATURES PARTICULARLY WITHIN
THE BOUNDARY LAYER AND CLOSEST TO THE GROUND WILL REMAIN ONLY
MARGINALLY SUPPORTIVE OF SIGNIFICANTLY ACCUMULATING SNOW.  USED A
4-WAY MODEL BLEND INVOLVING THE GFS/ECMWF/CANADIAN/UKMET FOR THIS
PARTICULAR SYSTEM...WHICH EMPHASIZED THE WARMER SIDE OF THE
GUIDANCE AND EXCLUDED THE COLDER NAM AND SREF MEAN...RESULTING IN
LOW PROBABILITIES OF 4 INCHES OF SNOW FOR PORTIONS OF MICHIGAN AND
OHIO TODAY AND TONIGHT.

ANOTHER SURFACE LOW WILL DEVELOP OVER THE EASTERN OH VALLEY MONDAY
NIGHT BEFORE ACCELERATING THROUGH CENTRAL NY ON TUESDAY IN
ASSOCIATION WITH APPROACH OF ITS LONGWAVE TROUGH...WITH RAIN
LIKELY MIXING WITH SNOW BEFORE TRANSITIONING TO ALL SNOW AND
EVENTUALLY ENDING BEHIND THE LOW...PARTICULARLY FOR THE HIGHER
ELEVATIONS ACROSS PA/NY/VT/NH/ME...SUPPORTING LOW PROBABILITIES OF
4 INCHES OF SNOW. 

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

...ROCKIES...

UPSLOPE FLOW ALONG THE NORTHERN AND EASTERN FACING SLOPES OF THE
NORTHERN-CENTRAL ROCKIES WILL BECOME THE PRIMARY MECHANISM FOR
ASCENT TUESDAY AND WEDNESDAY AS THE VIGOROUS SHORTWAVE TROUGH
PRESENTLY NEARING THE PACIFIC NORTHWEST CROSSES THE REGION. 
GENERALLY PREFERRED A SOLUTION CLOSE TO THE INTERMEDIATE
ECMWF/UKMET FOR DETERMINING THE LIQUID EQUIVALENT AMOUNTS AND
P-TYPES VERSUS THE MORE AMPLIFIED NAM/GFS WHICH HAD LESS MODEL
SUPPORT.  THE RESULT IS LOW PROBABILITIES OF 8 INCHES OR MORE OF
SNOW FOR THE TETONS AND CENTRAL ROCKIES...WITH PERHAPS A FOOT OR
MORE FOR THE EASTERN FACING SLOPES IN COLORADO.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

...UPPER MIDWEST...

USED THE WEAKER AND FLATTER SOLUTIONS OF THE ECMWF/UKMET OVER THE
STRONGER NAM/GFS FOR THE SHORTWAVE TROUGH PRESENTLY NEARING THE
PACIFIC NORTHWEST THAT REACHES THE PLAINS ON WEDNESDAY WITH BROAD
AND DEEP ASCENT FORMING ALONG THE PATH OF THE SURFACE LOW CROSSING
IOWA INTO WISCONSIN.  THE WEAKER/FLATTER SOLUTIONS SUPPORT LESS
SNOW THAN THE NAM/GFS.  OTHERWISE...THE MODEL SPREAD IS ABOUT
AVERAGE...BUT STILL WITH ONLY LIMITED CONFIDENCE GIVEN THE ROLE OF
A SHORTWAVE TROUGH REACHING SOUTH CENTRAL CANADA BY WEDNESDAY
NIGHT...WHICH MAY INTERACT WITH THE TROUGH ENTERING THE
PLAINS...THUS AFFECTING ITS INFLUENCE.  MIXED PRECIPITATION SEEMS
LIKELY WITH THIS PARTICULARLY EVENT AS WELL GIVEN THE ISENTROPIC
LIFT REGIME NORTH OF THE LOW...WHERE TEMPERATURES WILL LIKELY BE
BELOW FREEZING.  HOWEVER...THE PROBABILITIES FOR 0.25 INCHES OF
ICE WERE TOO LOW TO INCLUDE BASED ON THE SPREAD.  THUS...DEPICTED
MODERATE AND LOW PROBABILITIES OF 4 INCHES AND 8 INCHES OF SNOW
RESPECTIVELY INSTEAD DUE TO SLIGHTLY HIGHER CONFIDENCE.

JAMES