Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Tue Oct 19 2021

Valid 12Z Tue Oct 19 2021 - 12Z Thu Oct 21 2021

...Upper level low going cross country this week to produce heavy mountain
snow in the Rockies and severe weather in the Midwest...

...A pair of Pacific storm systems to kickoff an extended period of
unsettled weather from the Pacific Northwest to Northern California...

...Temperatures gradually warming up in the East, staying seasonally cool
in the West; showers and thunderstorm possible along the central Gulf
Coast; Elevated Risk for Fire Weather in the central High Plains...

An upper low over Utah is advancing east towards the central Rockies later
today, generating lower elevation rainfall and periods of mountain snow
along its route. Winter Storm Warnings have been issued for parts of
Wyoming, including the Wind River and Big Horn mountains ranges where 1 to
2 feet of snowfall is expected. Light accumulations are also possible from
the Wasatch and Colorado Rockies to the Black Hills of South Dakota.
Within the warm sector of a strengthening low pressure system over the
central Plains, scattered thunderstorms are expected to flare up from
central Nebraska to the Upper Mississippi Valley. In fact, a Marginal Risk
for severe weather is in place for parts of the Midwest this evening. The
wave of low pressure tracks into the Great Lakes by Wednesday forcing
showers and thunderstorms to develop from the Midwest and mid-Mississippi
Valley to the eastern Corn Belt. This storm system's swath of heaviest
rainfall is forecast to occur from southern South Dakota and southern
Minnesota to central Wisconsin.

Farther west, the West Coast is preparing for what will feel like a never
ending series of Pacific storm systems directing atmospheric river after
atmospheric river over the next seven days. The first storm system arrives
late Tuesday into Wednesday ushering Pacific moisture into Northern
California and up the coast to western Washington. Some light snowfall
accumulations in the higher terrain of the northern Sierra Nevada and
Cascades are possible, but rainfall totals over one inch are likely along
the coastal range of Northern California and into the lower elevated areas
along the slopes of the northern Sierra Nevada. Overall this is good news
for drought stricken areas of California and Oregon, but as an even more
powerful storm system approaches the second half of the week (and more
subsequent storm systems to follow in the medium range), burn scar areas
could become subjected to debris flows and flash flooding. A Day 3
Marginal Risk for Excessive Rainfall has been issued for Thursday in parts
of Northern California for not only potentially heavy rainfall rates, but
to highlight the opportunity for debris flows and rapid run-off near burn
scar areas.

Elsewhere, high pressure sliding east over the Southeast region allows for
the return of southerly flow in the Mid-South today and eventually
reaching the East Coast late Wednesday into Thursday. The result is
abnormally warm temperatures making a comeback after a few days worth of
seasonally cooler conditions. Meanwhile, due to the persistent rounds of
upper troughs slamming into the western third of the Lower 48,
temperatures will generally stay on the cooler than normal side, although
some parts of the interior Northwest may witness abnormally mild
conditions. In the South, areas of showers and thunderstorms may lead to
locally heavy totals along the Central Gulf Coast mid-week due to a weak
mid-level disturbance nearby. Last but not least, there is an Elevated
Risk for fire weather conditions in parts of the central High Plains. Red
Flag Warnings have been posted in southeast Colorado and southwest Kansas
due to the favorable fuels present for fire weather.

Mullinax

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