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KF5JRV > WX 14.12.16 14:24l 60 Lines 3145 Bytes #999 (0) @ USA
BID : 6974_KF5JRV
Read: GUEST
Subj: NWS USA WX Forecast
Path: IW8PGT<CX2SA<N9PMO<NS2B<KF5JRV
Sent: 161214/1216Z 6974@KF5JRV.#NWAR.AR.USA.NA BPQK6.0.13
Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
232 AM EST Wed Dec 14 2016
Valid 12Z Wed Dec 14 2016 - 12Z Fri Dec 16 2016
...Pacific storm system to bring a multi-day period of potentially heavy
rain and snow to the western U.S...
...Arctic air mass poised to overspread much of the north central and
northeastern U.S...
A Pacific low pressure system accompanied by an expansive plume of
moisture will spread rain and mountain snow into portions of the West
coast and the Great Basin/Intermountain West today. Cold air in place over
the interior West will allow precipitation to fall as snow. Warmer air
will gradually push into the region as the low pressure system approaches,
raising snow levels Wednesday night and Thursday. The rapid progression of
the warm front northward could also result in areas of sleet or freezing
rain at lower elevations where cold air could remain trapped for a longer
period of time. Snow levels will begin to lower once again across the
Northwest and northern Intermountain West Thursday night and Friday as the
main upper-level trough pushes inland. Heavy mountain snow and valley rain
will also spread into the central Rockies by Thursday night and Friday.
The potential exists for significant snow accumulations across portions of
the Great Basin, northern Intermountain West, Rockies, and the Pacific
Northwest, along with ice accumulation in the valleys of the Northwest.
Additionally, flooding rains are possible across much of central and
northern California. The threat for heavy precipitation is expected to
persist into Thursday and Friday, gradually shifting southward along the
West Coast, as multiple waves of low pressure move along the frontal
boundary into the West Coast. Please refer to products issued by local NWS
forecast offices for further details specific to your area.
Across the central and eastern U.S., the main weather story over the next
few days will be the arctic air mass overspreading many areas. An area of
high pressure originating in Canada has moved southward into the north
central U.S. early this morning. As this high continues to drift
southeastward through the next few days, a very cold air mass will
overspread areas from the northern plains and Midwest to the Ohio valley,
Mid-Atlantic, and Northeast in the wake of a fast-moving arctic cold
front. High temperatures today are expected to be 20 to 30 degrees below
average over the north central U.S., with these cold temperatures
spreading eastward on Thursday. The front will also reinvigorate lake
effect snows downwind of the Great Lakes later today into Thursday. By
Friday, another arctic high will begin to bring a renewed blast of arctic
air into the northern High Plains. At the same time, moisture associated
with the western U.S. storm system will begin to overspread the central
U.S. As a result, snow is expected to develop Thursday night into Friday
across much of the northern plains, with mixed precipitation possible
across the central plains.
Ryan
Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
73 Scott KF5JRV
KF5JRV.#NWAR.AR.USA.NA
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