Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
250 PM EST Sat Jan 07 2023

Valid 00Z Sun Jan 08 2023 - 00Z Tue Jan 10 2023

...Relentless parade of atmospheric rivers to produce additional instances
of heavy rain and mountain snow across much of northern/central
California...

...Scattered showers and thunderstorms stretch from the southern
Appalachians to the western Gulf Coast through Sunday...

...Light rain and a wintry mix expected to track across the Midwest to the
northern Mid-Atlantic by early Monday...

Several rounds of anomalous atmospheric moisture content being flung into
the West Coast will lead to additional hazardous weather conditions across
central and northern California through at least the beginning of next
week. The next system to produce heavy rain and mountain snow is already
impacting northern California and into the San Francisco Bay area this
afternoon. Heavy precipiation is forecast to expand further south into
central California tonight, while also spreading heavy snow into much of
the Sierra Nevada. With terrain already saturated from previous rainfall,
additional bursts of heavy rain could lead to moderate rises on rivers,
flooding of poor drainage areas, and urban/roadway flooding. This rainfall
will also further prime the soils ahead of what is expected to be an even
stronger atmospheric river poised to impact the Golden State on Monday.
Several additional inches of precipitation can be expected to begin
impacting the region late Sunday night into early Monday morning, with
persistent moderate to heavy rain lasting through Monday night. The
longevity and intensity of rain, combined with the cumulative effect of
successive heavy rain events dating back to the end of December, will lead
to widespread and potentially significant flood impacts. Minor to major
river flooding is expected, with record high river levels also possible. A
Moderate Risk (level 3/4) of Excessive Rainfall is in effect for Monday
across much of central California extending as far south as the Sierra
Madre. Flood and Flash Flood Watches have also been issued. For the higher
terrain of the Sierra Nevada, additional heavy snow will lead to lowering
visibility and treacherous travel. As snow load continues to increase on
top of several feet of accumulating snow from the past few weeks, the
threat of avalanches and infrastructure impacts will continue to increase.
Lastly, gusty winds may also accompany the progressing systems and create
the potential for downed trees and scattered power outages. Residents and
visitors are are advised to check their local forecast, never drive across
flooded roadways, and have both an emergency kit and evacuation plan in
place.

For the central and eastern U.S., mostly light precipitation is expected
near a weak and slow-moving frontal system as it treks from the Lower
Mississippi Valley to the Mid-Atlantic over the next few days. Showers and
thunderstorms developing along a cold front stretching to southern Texas
may contain isolated damaging wind gusts and large hail over parts of
southeastern Texas through tonight. Otherwise, locally heavy rainfall
rates may extend into the Tennessee Valley and create the risk of isolated
flash floods.

On the northern side of this system a light wintry mix and cold rain will
extend from the Midwest tonight before reaching the northern
Mid-Atlantic/central Appalachians on Sunday. While impacts are expected to
be minimal, a few slick roadways cannot be ruled out where light freezing
rain and/or snowfall occurs, especially during the overnight hours.

Tranquil and relatively warm weather is expected elsewhere throughout the
Lower 48. Highs into the 60s and 70s are forecast over much of the
southern Plains and Southeast by Monday, with 50s reaching back into
Mid-Mississippi Valley and Mid-Atlantic.


Snell

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