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
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
 
(Latest Discussion - Issued 1952Z Apr 01, 2015)
 
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 PM EDT WED APR 01 2015

VALID 00Z THU APR 02 2015 - 00Z SUN APR 05 2015


DAYS 1 TO 2...

...CENTRAL ROCKIES/HIGH PLAINS...

A SHORTWAVE TROUGH IS FORECAST TO MOVE OUT OF THE NORTHERN PLAINS
AND INTO THE GREAT LAKES ON THURSDAY/DAY 1...WITH ITS ASSOCIATED
COLD FRONT DROPPING SOUTH INTO THE SOUTHERN PLAINS AND SOUTHERN
COLORADO.  MEANWHILE...AN OTHER TROUGH IS FORECAST TO MOVE
EASTWARD FROM THE GREAT BASIN STATES.  THE COMBINATION OF A
BUILDING ANTICYCLONE TO THE NORTH BEHIND THE FRONT AND THE
APPROACHING SHORTWAVE SHOULD ALLOW POST-FRONTAL UPSLOPE FLOW TO
DEVELOP AS A SURFACE LOW REFORMS IN SOUTHEASTERN COLORADO AND THEN
MOVES EAST NORTHEASTWARD.  MODERATE TO HEAVY SNOW IS EXPECTED TO
DEVELOP IN THE EXIT REGION OF AN AMPLIFYING UPPER JET AT THE BASE
OF THE APPROACHING TROUGH ACROSS CENTRAL AND NORTHERN COLORADO
INTO THE PLAINS OF EASTERN COLORADO.   SIX TO 12 INCH SNOWS ARE
POSSIBLE ALONG THE FOOTHILLS OF THE COLORADO ROCKIES WITH A LOW
PROBABILITY OF LOCALLY GREATER THAN A FOOT OF SNOW.  THE AMPLITUDE
OF THIS SYSTEM APPEARS TO BE SLIGHTLY WEAKER AND FARTHER NORTH
THAN IN PREVIOUS FORECASTS POSSIBLY RESULTING IN SLIGHTLY LOWER
SNOWFALL ACCUMULATIONS THAN INDICATED YESTERDAY.   A MULTI MODEL
BLEND WAS USED TO GENERATE THE INITIAL DETAILS OF THE FORECAST
WHILE EARLY MORNING MODEL SOLUTIONS WERE USED TO FINE TUNE THE
DETAILS.

DAYS 2 TO 3...

...UPPER OHIO VALLEY/LOWER GREAT LAKES/NORTHEAST...

THE AFOREMENTIONED TROUGH OVER THE GREAT BASIN CONTINUES TO MOVE
EASTWARD AND APPROACHES THE EAST COAST ON FRIDAY INTO EARLY
SATURDAY.  LOW PRESSURE MOVES FROM THE SOUTHERN PLAINS
NORTHEASTWARD ACROSS THE LOWER OHIO VALLEY ACROSS THE MIDDLE
ATLANTIC STATES BEFORE MOVING JUST EAST OF NEW ENGLAND BY EARLY
SATURDAY.  THERE IS STILL QUITE A VARIATION BETWEEN MODELS IN THIS
DEVELOPING SYSTEM WITH THE INTENSITY OF THIS SYSTEM RANGING FROM
RELATIVELY MODEST TO SIGNIFICANT.  AS A RESULT...AS COLD AIR MOVES
IN WITH THE DEVELOPING SYSTEM...RAIN CHANGING TO SNOW APPEARS TO
BE QUITE POSSIBLE FROM THE UPPER OHIO VALLEY/LOWER GREAT LAKES
WITH MOSTLY LIGHT AMOUNTS TO INCREASINGLY HEAVIER ACCUMULATIONS
FROM NORTHWESTERN PENNSYLVANIA ACROSS WESTERN AND NORTHERN NEW
YORK AND NORTHERN NEW ENGLAND. WHILE THE 12Z NAM REMAINS SLIGHTLY
FARTHER EAST THAN SOME OF THE OTHER MODELS...THE 12Z GFS REMAINS
NOT QUITE AS ROBUST AS THE 00Z AND 12Z ECMWF/12Z UKMET. USED A
COMBINATION OF THESE MODELS AND THEIR RESPECTIVE MEANS...INCLUDING
THE 9Z SREFMEAN TO COME UP WITH A COMPROMISE FORECAST WITH A
MODERATE TO HIGH PROBABILITY OF 4 TO 8 INCHES OF SNOW FROM
NORTHWESTERN PENNSYLVANIA NORTHEASTWARD ACROSS WESTERN AND
NORTHERN NEW YORK INTO NORTHERN NEW ENGLAND.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

KOCIN