Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
226 AM EST Thu Jan 21 2021

Valid 12Z Thu Jan 21 2021 - 12Z Sat Jan 23 2021

...Heavy rain and possible flash flood threat decreasing across portions
of the Desert Southwest Thursday morning...

...Heavy rain developing across the Lower Mississippi Valley/Southeast on
Thursday...

...Much need snows expected across the Sierra and Wasatch Friday into
Saturday...

...An active Lake effect snow pattern begins Thursday and continues
through Friday downwind of the Great Lakes...

A strong mid to upper level low will be pushing eastward along the
Southwest U.S./northwest Mexico border region on Thursday and then
accelerate across the Southern Plains and into the Southeast on Friday. 
This system is currently producing heavy rains over portions of the Desert
Southwest with this heavy rain and flash flood threat continuing into
Thursday morning before diminishing by Thursday afternoon. 

While conditions improve over the Southwest, they will become increasingly
wet farther to the east from portions of the Southern Plains, into the
Lower Mississippi Valley and Southeast Thursday into Friday.  Widespread
rains are expected across these areas with the heaviest totals in a stripe
from far eastern Texas, across central to northern Louisiana, central to
southern Mississippi, southern Alabama into southern Georgia.  Aside from
eastern Texas into far northwest Louisiana, much of this region has had
below average precipitation this month resulting in stream flows at or
below normal levels.  This should reduce the threat of flash flooding with
only a marginal risk depicted across portions of this region Thursday into
Friday.

Another storm system is expected to push into northern California on
Friday and move eastward into the Great Basin on Saturday.  This system
will bring some much needed heavy snows to the Sierra of California and
Wasatch of Utah.  Much of California into the Great Basin is well below
average in precipitation this season, experiencing severe to exception
drought levels.

Two cold fronts will be sweeping across the Great Lakes Thursday into
early Friday producing favorable cold westerly to northwesterly flow
across the unfrozen Great Lakes.  Lake effect snow showers will increase
in coverage and intensity Thursday and continue through Friday.  Locally
heavy snowfall accumulation are likely with the heaviest totals expected
over western and northwestern portions of New York State, downwind of
Lakes Erie and Ontario, northern portions of the Lower Peninsula of
Michigan, downwind of northern Lake Michigan and along the north coast of
the Upper Peninsula of Michigan, downwind of Lake Superior.

Oravec

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