Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
438 PM EDT Mon Oct 17 2022

Valid 00Z Tue Oct 18 2022 - 00Z Thu Oct 20 2022

...Widespread record tying/breaking morning lows will bring first freeze
of the season to portions of the Midwest and South...

...Wintry precipitation continues for the Great Lakes Region...

...Heavy rain forecast for Maine on Tuesday, with scattered instances of
flash flooding possible...

A deep upper-level low pressure system currently sits over the Great Lakes
as a strong cold front continues to push south and east of the Gulf and
Atlantic coasts, leading to a combination of chilly, well below normal
temperatures for much of the eastern 2/3rds of the country, as well as
wintry precipitation for the Great Lakes. A cold continental airmass has
begun to settle in as high pressure builds southward over the central and
southern U.S. Widespread, well-below normal high and low temperatures are
forecast through the short-term period (Wednesday evening), with some
upwards of 25 degrees below normal and many record tying/breaking
temperatures possible. Freeze Warnings are in effect across broad portions
of the Central Plains, Middle Mississippi Valley, Ohio Valley, Tennessee
Valley, Mid-South, and Central/Southern Appalachians. Freeze Watches are
in effect further south from northern portions of the Southern Plains east
through the Lower Mississippi Valley and into the Piedmont. Lows in the
mid-20s to low 30s are currently forecast for locations in the Freeze
Warnings Tuesday morning with lows in the low to mid-30s for areas in the
Freeze Watches on Wednesday morning.

Areas to the north of the Freeze Watches and Warnings, despite already
having seen their first freeze, will still experience well below normal,
frigid temperatures Tuesday, with highs in the upper-30s to low 40s for
the Northern Plains and Upper Great Lakes and low to mid-40s for the
Middle Missouri Valley east to the Lower Great Lakes. Highs on Wednesday
should warm by about 5-10 degrees across the region. Further south, while
a widespread freeze is not currently expected, morning lows on Wednesday
will bottom out in the upper-30s to low 40s across much of the Gulf Coast.

In addition to the chilly temperatures, additional waves of low pressure
rotating around the broader upper-level low will continue strong/gusty
northwesterly winds across portions of the Great Lakes with a wintry mix
of rain and snow showers expected through Wednesday. Any snow
accumulations should generally remain on the lighter side with the
exception of the Upper Great Lakes, particularly the Upper Peninsula of
Michigan. Snow showers today will taper off through the day tomorrow, with
total accumulations upwards of 6-12 inches possible for some higher
elevation, inland locations.

Heavy rain is forecast to the east of the cold front as it pushes through
Maine during the day Tuesday. Anomalously high moisture from the Gulf
Stream will be advected northward ahead of the front and help to enhance
rain rates/rainfall totals for showers and thunderstorms along the front.
There is a Slight Risk of Excessive Rainfall in effect for eastern Maine
where 2-4 inches of rainfall is forecast, with locally higher totals
between 5-8 inches in higher terrain areas possible, leading to the risk
for scattered instances of flash flooding.

Elsewhere, warm temperatures 10-20 degrees above average will continue for
much of the West the next couple of days as an upper-level ridge remains
in place. Highs Tuesday and Wednesday will be in the mid- to upper 70s for
most of the Northern Rockies, Pacific Northwest, and Great Basin, with 80s
for the I-5 urban corridor in Oregon. A warm front will move east over the
High Plains on Wednesday, bringing some relief from the chilly
temperatures to the Northern High Plains with highs in the mid-60s to
low-70s. 

Putnam

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