The Weather Prediction Center

Short Range Forecast Discussion

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Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
211 AM EST Tue Nov 21 2017

Valid 12Z Tue Nov 21 2017 - 12Z Thu Nov 23 2017

...More heavy rain expected for the Northwest and another cold
front will sweep through the central and eastern states...

The West Coast north of San Francisco will be quite active
weatherwise through the middle of the week with persistent onshore
flow and deep moisture moving inland.  The result of this
atmospheric river will be a heavy rainfall event along and west of
the Cascades, with the potential for amounts in excess of four
inches possible, particularly for western Washington.  Moderate to
heavy rain can also be expected for parts of the northern Rockies.
 Given the warm nature of this weather pattern and the resulting
high snow levels, very little in the way of snow is expected,
except for the highest peaks.  Some instances of flooding will
also be possible.

East of the Rockies, an arctic front will quickly sink southward
across the Plains and then reach the East Coast by Wednesday.  A
brief moderating trend in temperatures is expected across the
eastern U.S. ahead of this boundary, making for a pleasant day for
many locations on Tuesday.  By the time this front reaches the
coast, the airmass will have modified and not be as cold as what
the Plains and Midwest will experience.  Showers and a few
thunderstorms will be possible across Florida owing to easterly
flow from the Atlantic.  Warm and dry conditions will continue for
the Desert Southwest with highs near 90 degrees for the lower

D. Hamrick

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Last Updated: 211 AM EST Tue Nov 21 2017