Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
324 AM EDT Sun Oct 17 2021

Valid 12Z Sun Oct 17 2021 - 12Z Tue Oct 19 2021

...Seasonally cool temperatures along the Coasts and the Deep South;
warming up from the Northern Rockies to the Midwest...

...Upper trough to cause accumulating mountain snowfall and lower
elevation rainfall from the Pacific Northwest to the Intermountain West;
lake effect showers in the eastern Great Lakes; showers and storms
possible in South Florida...

After a remarkably warm first half of October along and east of the
Mississippi River, autumn has finally made its long awaited appearance
across the South and along the East Coast. Temperature departures both
today and Monday look to range anywhere from 5 to 15 degrees below normal
along the East Coast and as far south as South Texas. Meanwhile, after a
chilly few days in the central High Plains and Midwest, temperatures
rebound to abnormally warm levels in these regions. Daytime highs in these
areas will soar into the 70s with some 80s sprinkled in over the central
and southern High Plains. Farther west, the West Coast joins the East
Coast in witnessing much cooler temperatures than their neighbors in the
Heartland. As an upper trough tracks into the Intermountain West on
Monday, daily max temperature departures are forecast to range between 10
and 20 degrees below normal from the central Great Basin to the California
coast.

Precipitation-wise, while much of the country will be dry thanks to an
expansive area of high pressure, there are still a few areas likely to
contend with wet and even snowy weather. An amplifying upper trough taking
aim at the West Coast will direct Pacific moisture at the Pacific
Northwest today. This will lead to valley and coastal showers from
northern California to western Washington. Meanwhile, precipitation will
fall in the form of snow in the higher elevations of the northern Sierra
Nevada and Oregon Cascades. Most totals will only range between 2-6
inches, but the tallest peaks could pick up as much as a foot of snow. As
the upper trough becomes a closed upper low on Monday, the threat for snow
moves east into the Intermountain West with the Tetons, Wind River, and
Absaroka Ranges having the best chances of picking up 6-12 inches of
snowfall. Elsewhere, lake effect rain showers are set to develop down wind
of the Lakes Ontario and Erie. As the pressure gradient weakens throughout
the Great Lakes, bands of lake effect showers will dissipate sometime
Monday. Lastly, the cold front that ushered in much cooler conditions into
the East will potentially trigger spotty showers and thunderstorms in
South Florida later today.

Mullinax

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