Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
408 PM EDT Tue Apr 20 2021

Valid 00Z Wed Apr 21 2021 - 00Z Fri Apr 23 2021

...Snow is expected to spread quickly from the Central U.S. to the Midwest
today, and then across northern New England on Wednesday into Thursday...

...Subfreezing record cold temperatures expected across much of the
south-central U.S. Wednesday morning, shifting to parts of the eastern
U.S. Thursday morning...

...Critical fire weather threat over Arizona through Friday...

Late season snow event continues to spread eastward across the Ozarks into
the Ohio Valley as a developing area of low pressure is forecast to race
along the Alleghenies into the Northeast later today into tomorrow
morning. As the low pressure system progresses northeastward, rain and
mixed precipitation will continue to envelop the Midwest, before a swath
of wet snow falls along the Canadian border from New York into Northern
New England beginning Wednesday morning through Friday. 6 to locally 8
inches is possible along the border through Friday. As such, "Moderate"
impacts are expected in these locations from snow-load, per the Weather
Prediction Center Winter Storm Severity Index, and Winter Weather
Advisories are in effect for the region. Further south in the
Mid-Atlantic, some rain and a few rumbles of thunder are possible as the
storm moves through.

In the wake of the developing storm system, a bout of unseasonably cold
air is forecast to spill into the Central U.S. today and tomorrow, leading
to widespread freeze and frost concerns tonight across the
central/southern Plains and the Midwest. Freeze Watches and Warnings
extend continuously from north-central Michigan into central Texas.
Numerous daily record low temperatures are forecast to be tied or broken
on Wednesday morning as temperatures dip to below freezing, around 20-25
degrees below average for late April. Residents in these areas are
encouraged to take preventative measures to mitigate the impacts of
sub-freezing temperatures on vulnerable vegetation if possible. By Friday,
the frigid airmass will moderate as it drifts east, although low
temperatures will remain around 10 degrees below normal in the Central
U.S., with lows hovering in the mid-30's to 40's.

Meanwhile, active weather across Florida has been edging very slowly
southward into southern Florida ahead of a slow-moving front. A low
pressure wave forming on the front could bring additional heavy showers
and thunderstorms today across central Florida. Improving conditions
should begin Wednesday morning as the wave moves off into the Atlantic and
rain chances decrease across southern Florida. While excessive rain may be
problematic in Florida, dry, windy conditions will set the stage for a
fire weather threat in Arizona over the next three days as low pressure
deepens in the region. Accordingly, the Storm Prediction Center has issued
an Elevated Risk of fire weather today, and a Critical Risk tomorrow, with
the potential for additional impactful fire weather also highlighted on
Friday.  

Asherman/Kong

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