Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
420 PM EDT Mon Sep 19 2022

Valid 00Z Tue Sep 20 2022 - 00Z Thu Sep 22 2022

...Record breaking heat anticipated over the Central and Southern U.S
through midweek; strong Canadian cold front to bring relief over the
Plains...

...Increasing shower and thunderstorm coverage over the Pacific Northwest
and Four Corners Region could cause isolated-scattered flash flooding...

The main weather story over the CONUS today remains yet another heat wave
currently centered over the Central Plains beneath a strong, anomalous
upper-high anchored over Oklahoma. Current surface observations in the
Central/Southern Plains show temperatures climbing into the mid-upper 90's
(upwards of 20-25 degrees above normal for this time of year) on the warm
side of a slow moving warm front in the Missouri Valley. Several daily
high temperature records could fall in Kansas and Missouri this afternoon
as temperatures approach triple digits with continued daytime heating.
Unfortunately, the excessive heat is expected to amplify Tuesday over the
Central U.S. as heights rise on the periphery of a departing disturbance
over the Northeast. Accordingly, many daily high temperature records could
Tuesday fall over the Plains, Missouri Valley, and Upper-Mississippi
Valley, as current forecast highs in the upper-90's-triple digits tomorrow
approach 30 degrees above normal for this time of year. Relief from the
hot weather will begin to arrive on Tuesday as a strong Canadian cold
front associated with a clipper system slides down the Rockies Tuesday. By
Wednesday evening, the sweeping cold front is forecast to reach the
Texas-Oklahoma Panhandle, ushering in pleasant high temperatures in the
mid-upper 60's. Additional daily high temperature records could still fall
over the Tennessee/Mississippi Valleys on Wednesday however, as the very
hot warm-sector airmass will support an additional round of upper-90
degree highs.

Meanwhile, instances of training thunderstorms with excessive rainfall
rates could cause scattered flash flooding over the Interior Northeast and
New England today, where a Slight Risk of Excessive Rainfall is in effect.
To the west, low pressure off the California Coast will siphon a stream of
tropical moisture west of the Continental Divide, leading to increasing
thunderstorm coverage and isolated instances of flash flooding (Marginal
Risk of Excessive Rainfall) in Northern California and the Four Corners
through Midweek. A Slight Risk of flash flooding is depicted over the Four
Corners on the Day 3 Excessive Rainfall outlook, where highly anomalous
moisture will interact with the aforementioned low-pressure to support
organized thunderstorm activity which could fall atop sensitive areas such
as burn scars.

Asherman/Ziegenfelder


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