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Winter Weather Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 0842Z Oct 20, 2014)
 
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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
442 AM EDT MON OCT 20 2014

VALID 12Z MON OCT 20 2014 - 12Z THU OCT 23 2014


...DAY 1...

THE PROBABILITY OF HEAVY SNOW AND/OR SIGNIFICANT ICING IS LESS
THAN 10 PERCENT.

...DAY 2...

STRONG MOISTURE ADVECTION OVER THE PAC NW WILL BEGIN AS SOUTH TO
SOUTHWEST FLOW DEVELOPS IN ADVANCE OF AN APPROACHING SHORTWAVE.
MODELS STILL AGREE THAT THE RH SPIKES...ALTHOUGH THERMAL FIELDS
FROM THE VARIOUS MODELS ARE NOT UNANIMOUS THAT PCPN WILL BEGIN AS
SNOW EXCEPT AT THE HIGHEST ELEVATIONS OF THE BITTERROOTS. 

THE OPERATIONAL MODELS AND THEIR ASSOCIATED ENSEMBLES ONLY
SUPPORTED A SLIGHT RISK OF 4 INCHES IN THE FAR NORTHERN CASCADES
WHERE COLDER AIR WILL BE IN PLACE LONGEST AND WHERE MOISTURE WILL
BE AVAILABLE.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

...DAY 3...

THE ONLY RISK OF MORE THAN LIGHT SNOW SHOULD LINGER IN THE FAR
NORTHERN PORTION OF THE CASCADES IN WA WHERE THE MODELS AND
ENSEMBLES STILL POINTED TO A SLIGHT RISK OF 4 AND 8 INCH AMOUNTS. 

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

BANN