The Weather Prediction Center

Short Range Forecast Discussion

[Abbreviations and acronyms used in this product]
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Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
239 PM EST Fri Dec 19 2014

Valid 00Z Sat Dec 20 2014 - 00Z Mon Dec 22 2014

***Heavy rain and mountain snow for the Northwest U.S.***

***Rain for the Gulf Coast region***

Strong deep-layer flow from the Pacific will drive moisture into
the Northwest over the next several days. A strong upper jet
combined with a series of shortwaves rotating through the region
provides a broad environment of strong ascent. These ingredients,
combined with a strong low level jet intercepting the higher
terrain will lead to a prolong period of moderate to heavy
rainfall across the region and snow in the higher elevations.
Rainfall of several inches will be possible with snowfall of over
a foot. A cold front will move inland by tomorrow evening and
precipitation will spread into the intermountain west and central
and northern Rockies.

Along the Gulf coast, rainfall will continue to move slowly
eastward with the surface low. A frontal boundary extending
eastward from the surface low will become stationary and serve as
a focus for precipitation through the period. With the frontal
boundary draped along the Gulf coast, convection into the
Southeast will be elevated if at all. Light to moderate rainfall
can be expected north of the front but should diminish in time
with upper level forcing waning.


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Last Updated: 239 PM EST Fri Dec 19 2014