Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
245 PM EST Mon Dec 04 2023

Valid 00Z Tue Dec 05 2023 - 00Z Thu Dec 07 2023

...Excessive rainfall and instances of flooding are likely across parts of
western Washington Oregon and northern California over the next few days...

...Moderate upslope snow potential forecast across the Central
Appalachians Tuesday afternoon into Wednesday...

...Warming trend increases across the Great Plains through midweek...


Diffluence associated with a deep upper-level trough will direct anomalous
moisture into the Pacific Northwest focused along surface cold and warm
fronts. Snow levels will be high enough that most of the precipitation
that occurs will be in the form of rain. Thus, heavy rainfall is expected
across much of western Washington and northwest Oregon beginning tonight.
The Olympic Mountains will be particularly hard hit with a number of
dynamic and moisture ingredients coming together to produce several inches
of rainfall there in particular, but also over the northern Cascades and
down the coast into northwestern Oregon. There is a corresponding Moderate
Risk (at least 40%) of Excessive Rainfall leading to Flash Flooding over
the Olympics for tonight. The primary heavy rain threat shifts into
coastal portions of southern Washington and into Oregon on Tuesday where a
few more inches may accumulate. A pair of Slight Risks (at least 15%) of
Excessive Rainfall are in effect for the aforementioned coastal areas as
well as upslope portions of the northern Cascades.

Meanwhile, a deepening positively tilted trough swinging through the
Midwest will promote snowfall over portions of the Central Appalachians
beginning Tuesday afternoon. Moderate snow is possible over portions of
the southern Allegheny and Appalachian Plateau with lesser amounts
elsewhere in the region. Things should begin to wind down by Wednesday
evening. Upstream of here, a large ridge will develop over the central
part of the country and support a warming trend over the next several
days. Some high temperature anomalies in the Northern/Central Plains will
likely range from 15-30 degrees above average with some isolated
departures eclipsing that range. The heavy snow threat should diminish
across northern New England tonight while the inciting shortwave energy
and associated low pressure system move offshore.


Kebede


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php