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

Valid 00Z Mon Oct 18 2021 - 00Z Wed Oct 20 2021

...Seasonably 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. High temperature departures
tonight and into 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 will 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. This warm air mass
will eventually shift into the eastern half of the country mid to late
week. Farther west, the West Coast joins the East Coast in experiencing
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 will
take aim at the West Coast directing Pacific moisture at the Pacific
Northwest tonight. 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 expected to continue
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 tonight. Troughing in the Northeast
may lead to a light wintry mix for parts of northern New England Monday
night into Tuesday Morning. Elevated Fire conditions are expected to
continue for parts of the Northern Rockies and Central Plains this evening
due to to higher winds and dry air.

Kebede/Mullinax

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