Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
253 AM EST Fri Mar 10 2023

Valid 12Z Fri Mar 10 2023 - 12Z Sun Mar 12 2023

...There is a High Risk of excessive rainfall over parts of California...

...Heavy snow over the higher elevations over the Lower Great Lakes and
Upper Midwest; Pockets of rain/freezing rain over parts of the Central
Appalachians on Friday and the Middle Missouri Valley on Saturday...

...There is a Slight Risk of severe thunderstorms over parts of the
Southern Plains and Lower Mississippi Valley on Saturday...

A storm over the Ohio Valley will move eastward off the northern
Mid-Atlantic Coast by Saturday morning. A winter storm is set to track
through the Lower Great Lakes into Friday, bringing periods of heavy snow
with snow rates up to 1 inch per hour at times. Additional snowfall
accumulations of 4-8 inches are expected across southern Wisconsin, far
northern Illinois, southern Michigan, and the Lower Great Lakes. Travelers
need to plan for impacts, including snow-covered roads, reduced
visibility, and difficult travel across the impacted areas. Whiteout
conditions are possible within the heaviest snow bands. As the storm moves
east, several inches of snow are expected across the northern
Mid-Atlantic, including north-central Pennsylvania and the Poconos, which
will cause some travel impacts and disruptions. In addition, along the
rain/snow line, some pockets of rain/freezing rain will develop over parts
of the Central Appalachians on Friday.

Furthermore, rain will develop along the associated front over parts of
the Central Appalachians and the Mid-Atlantic. Moreover, showers and
strong to severe thunderstorms will develop over parts of the Southeast.
Therefore, the SPC has issued a Marginal Risk of severe thunderstorms over
parts of the Southeast through Saturday morning. The hazards associated
with these thunderstorms are frequent lightning, severe thunderstorm wind
gusts, hail, and a minimal threat of tornadoes.

Meanwhile, a front over the Pacific Northwest into Northern California
will move eastward to the Tennessee Valley by Sunday. The system will
produce a strong winter storm lasting into Friday. The storm will continue
to affect the West Coast, particularly California, through Friday with a
burst of heavy precipitation. Heavy rain and high snow levels are likely
over parts of California. Warm air will be associated with the storm, with
rain falling on existing snowpacks up to 8500 feet. The highest snow
levels, heaviest rainfall, and highest rainfall rates are expected in
Central California. Considerable flooding impacts are possible across
portions of the central coast and San Joaquin Valley. Rain and snowmelt
will lead to flooding. The most significant snowmelt, and overall flooding
threat, is expected below 5000-foot elevation in areas with shallow
snowpack. Creeks and streams in the foothills of the Sierra Nevada will be
most vulnerable to flooding from rain and snowmelt.

Furthermore, heavy wet snow will occur at higher elevations. The higher
elevations in Northern California and the Sierra Nevada will receive
heavy, wet snow. The snow will lead to difficult travel and, combined with
an already deep snowpack, may lead to increasing impacts from the depth
and weight of the snow.

Moreover, the WPC has issued a High Risk of excessive rainfall over
California through Saturday morning. Severe, widespread flash flooding is
expected with the storm. Areas that normally do not experience flash
flooding will flood. Lives and property are in great danger from Friday
into Saturday morning.

The threat of excessive rainfall reduces significantly on Saturday.
Therefore, the WPC has issued a Marginal Risk of excessive rainfall over
parts of California from Saturday into Sunday morning. The associated
heavy rain will create localized areas of flash flooding, affecting areas
that experience rapid runoff and burn scars.

As the storm moves out of the Rockies onto the Plains, an area of showers
and severe thunderstorms will develop over parts of the Southern Plains
and Lower Mississippi Valley. Therefore, the SPC has issued a Slight Risk
of severe thunderstorms over parts of the Southern Plains and Lower
Mississippi Valley from Saturday into Sunday morning. The hazards
associated with these thunderstorms are frequent lightning, severe
thunderstorm wind gusts, hail, and a few tornadoes.

The northern half of the system will produce heavy snow over parts of the
Northern Plains on Friday and over parts of the Upper Mississippi Valley
on Saturday. An area of rain will also develop over parts of the Middle
Mississippi Valley. Along the rain/snow line, pockets of rain/freezing
rain will develop over parts of the Central Plains and Middle Mississippi
Valley on Saturday. The snow will move into the Great Lakes by Sunday.


Ziegenfelder


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