Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Sun Oct 10 2021

Valid 12Z Sun Oct 10 2021 - 12Z Tue Oct 12 2021

...A pair of storm systems tracking through the Nation's Heartland to
generate severe weather and excessive rainfall from the Southern and
Northern Plains to the Great Lakes...

...September-like heat to continue across much of the eastern half of the
Lower 48; potential for tropical development off the Carolina Coast
tonight and into Sunday...

...Amplifying upper trough to inject some of the coldest air of the season
into the West early next week; heavy mountain snow and much below normal
temperatures likely...

An increasingly active weather pattern continues to take shape across U.S.
mainland as a couple of strong upper-level troughs are forecast to force
their way eastward through the western U.S. against the slow-moving regime
near the East Coast.  The first upper trough is responsible for the
formation a pair of low pressure systems across the mid-section of the
country.  The system moving across the northern Plains this morning is
responsible for triggering severe thunderstorms over parts of the Dakotas
into Minnesota.  This low will head into southern Canada by tonight with
the threat of severe weather quickly diminishing over the upper Midwest. 
In the wake of this system, another low pressure system is forecast to
form over the southern Plains today, where a threat for severe weather
will rapidly transpire tonight over the southern Plains.  The Storm
Prediction Center is indicating an Moderate Risk for severe storms across
central Oklahoma for tonight.  The low pressure system will continue to
develop and track into the Great Lakes by Tuesday morning with the threat
of severe thunderstorms spreading further up the mid-Mississippi Valley to
the Great Lakes Monday into early Tuesday.

Along the East Coast, the National Hurricane Center continues to monitor a
low pressure system forming near a stalled front just of the North
Carolina coast.  This system showed signs of acquiring some tropical
characteristics early this morning.  However, the main upper-level support
is forecast to lift northeastward away from the system during the next
couple of days.  Some heavy rain and gusty conditions can be expected
along the North Carolina coastal areas and may skirt the Virginia eastern
shores this morning before edging out to sea later today.  Some showers
are possible to extend further north into southern New England on Monday
as the associated frontal system will remain slow to exit the East Coast.

Meanwhile, a frontal system tracking into the Pacific Northwest this
evening is associated with a deepening upper trough diving south through
British Columbia. The associated cold front is set to usher in the coldest
air of the season to date in the western third of the country by Monday.
In wake for the cold frontal passage, high winds will ensue from the Great
Valley of California to the Desert Southwest. High Wind Watches have been
issued in advance due to the heightened risk for hazardous wind gusts.
Freeze Watches have also been posted for the western Nevada Basin. As the
front crosses the northern Rockies, plummeting snow levels give way to
periods of snow breaking out Sunday evening. By Monday, as the trough
continues to strengthen, so will the evolving frontal system in the West,
leading to heavy snow for the many mountain ranges in the Intermountain
West. Latest snowfall forecast indicate anywhere from 6 to 12 inches
(locally higher amounts possible) may accumulate in the northern Rockies,
including ranges such as the Absarokas, Teton, Wind River, and Big Horns.
This upper trough becomes quite intense by early Tuesday, setting the
stage for copious amounts of snow in parts of the Rockies and a potential
severe weather outbreak in the southern and central Great Plains.

Kong/Mullinax


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