Quantitative Precipitation Forecast
Issued by NWS

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378
FOUS11 KWBC 162043
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
443 PM EDT THU MAR 16 2017

VALID 00Z FRI MAR 17 2017 - 00Z MON MAR 20 2017

...UPPER MIDWEST/GREAT LAKES/NORTHEAST...

A MID-UPPER LEVEL SHORTWAVE TROUGH EMANATING FROM WESTERN CANADA
AND THE PACIFIC NORTHWEST WILL BE MOVING ALONG THE U.S./CAN
BORDER...AMPLIFYING AS IT MOVES ACROSS CENTRAL CANADA AND THE
NORTHERN U.S. PLAINS DURING THE OVERNIGHT HOURS TONIGHT.  LOW
LEVEL THETA-E ADVECTION ALONG WITH FAVORABLE UPPER JET DYNAMICS IS
FORECAST TO PRODUCE LIGHT TO MODERATE PRECIPITATION ACROSS THE
NORTHERN PLAINS AND THE UPPER MIDWEST...WITH THERMAL PROFILES
SUPPORTING A SWATH OF ACCUMULATING SNOWS ACROSS PORTIONS OF
NORTHEASTERN MN...THE WESTERN U.P. OF MI AND NORTHERN WI INTO
PARTS OF LOWER MI AND PARTS OF THE OH VALLEY.

WITH THE TROUGH CONTINUING TO AMPLIFY AND SLIDE EAST ON FRI...THE
GREATER POTENTIAL FOR PRECIPITATION AND ACCUMULATING SNOWS IS
EXPECTED PUSH EAST ACROSS THE GREAT LAKES.  SNOW ACCUMULATIONS ARE
EXPECTED TO BE GENERALLY LIGHT...WITH ONLY A SLIGHT RISK FOR
AMOUNTS OF 4-INCHES OR MORE CENTERED ACROSS THE EASTERN U.P. ON
DAY 2 (ENDING 00 UTC SUN).

MODEL GUIDANCE SHOWS A MID-UPPER LEVEL LOW MAKING ITS WAY FROM THE
UPPER GREAT LAKES ACROSS THE LOWER LAKES INTO THE NORTHERN MID
ATLANTIC.  A SURFACE LOW DEVELOPING ALONG THE MID ATLANTIC COAST
ON FRIDAY STILL HAS THE POTENTIAL TO THROW ENOUGH MOISTURE BACK
TOWARDS THE NORTH AND WEST TO SUPPORT SOME STEADIER SNOWS ACROSS
PORTIONS OF EASTERN UPSTATE NY AND SOUTHERN NEW ENGLAND.

THE PROBABILITY OF ICE ACCUMULATIONS OF 0.25 INCH OR MORE IS LESS
THAN 10 PERCENT.

...PACIFIC NORTHWEST...

FOLLOWING THE PASSAGE OF THE AFOREMENTIONED SHORTWAVE
TROUGH...PRECIPITATION IS EXPECTED TO BRIEFLY WANE ACROSS THE
REGION AS A SHORTWAVE RIDGE BEGINS TO BUILD ACROSS THE REGION ON
FRI.  STEADIER PRECIPITATION IS FORECAST TO RETURN TO THE REGION
FRI NIGHT INTO SAT AS THE BUILDING RIDGE GETS NUDGED EASTWARD BY
AN APPROACHING TROUGH.  SNOW LEVELS WILL REMAIN FAIRLY HIGH
THROUGH FRIDAY NIGHT OR EARLY SATURDAY WITH ANY HEAVY SNOWS LIKELY
TO REMAIN CONFINED TO THE HIGHER PEAKS OF THE NORTHERN CASCADES.
SNOW LEVELS WILL BEGIN TO DECREASE BY THE AFTERNOON HOURS ON SAT
AS THE TROUGH AND ITS ASSOCIATED COLD FRONT BEGIN TO PUSH THROUGH
THE NORTHWEST.

THE PROBABILITY OF ICE ACCUMULATIONS OF 0.25 INCH OR MORE IS LESS
THAN 10 PERCENT.

BANN

$$





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