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Winter Weather Forecast Discussion
 
(Latest Discussion - Issued 2317Z May 17, 2015)
 
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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
630 PM EDT SUN MAY 17 2015

VALID 00Z MON MAY 18 2015 - 00Z THU MAY 21 2015

DAYS 1 TO 3...

...NORTH DAKOTA THIS EVENING AND OVERNIGHT...

UPPER LOW OVER THE EASTERN DAKOTAS/WESTERN MN WILL LIFT SLOWLY NE
INTO SOUTHERN ONTARIO JUST N OF LAKE SUPERIOR BY 00Z TUE. STRONG
DEEP-LAYER ASCENT ASSOCIATED WITHIN THE CCB/TROWAL ALONG THE
ROBUST MID LEVEL DEFORMATION ZONE IS GETTING A SIGNIFICANT BOOST
FROM THE LFQ AND RRQ OF THE UPPER LEVEL JET STREAKS OVER THE
NORTHERN MS VALLEY AND SOUTH-CENTRAL CANADA RESPECTIVELY. THE
INCREASING CAA WITHIN THE BOUNDARY LAYER WILL COUPLE WITH
FAVORABLE COLUMN (DIABATIC) COOLING PER THE STRONG DEEP-LAYER
VERTICAL ASCENT AND PRECIPITATION RATES TO ALLOW FOR FAIRLY QUICK
TRANSITION FROM R OR R/S OVER TO SNOW THIS EVENING...WITH THE
SNOWFALL ACCUMULATION EFFICIENCY GETTING A BOOST CLOSER TO AND
AFTER SUNSET (PARTICULARLY AT HIGHER ELEVATIONS ABOVE 1.5 KFT).
PROBABILITIES FOR 4+ INCHES ARE HIGHEST ACROSS NORTH CENTRAL
ND...WHERE UPWARDS OF 5-6" WILL BE POSSIBLE ALONG THE CANADIAN
BORDER.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT DAYS
1-3.

HURLEY