Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
408 AM EDT Sat Sep 10 2022

Valid 12Z Sat Sep 10 2022 - 12Z Mon Sep 12 2022

...Kay continues to weaken, but heavy rainfall and flash flooding remain a
threat for portions of southern California and the Desert Southwest...

...The record breaking heat across much of the West comes to an end, but
an elevated risk of Fire Weather will continue in the Pacific Northwest...

...Heavy Rain possible in the Midwest, Mid-Atlantic and Florida Gulf
Coast...

...Strong cold front to bring much cooler temperatures to the Plains and
Upper/Middle Mississippi Valley...

Kay weakened to a post tropical cyclone this morning, but is forecast to
continue streaming anomalous moisture into southern California and the
Desert Southwest as it continues to wobble its way farther into the
eastern Pacific this weekend. Bands of heavy rain and thunderstorms moving
through the Southwest may produce flash flooding, especially over areas
with sensitive soils. A slight risk of excessive rainfall is in effect for
parts of interior southern California, southern Nevada and northwestern
Arizona today. High temperatures will remain below average while lows are
above average this weekend thanks to the increased cloud cover from Kay.

The upper ridge responsible for record breaking heat across the West will
shift east a bit in response to an upper low approaching the Pacific
Northwest. Both of these upper level features will combine to produce
above average temperatures across the Northwest this weekend. Fortunately,
none of this warm weather will break records, but there's an elevated risk
of fire weather. Red Flag warnings are in effect for much of the Pacific
Northwest.

An amplified trough will close off into an upper low over the Midwest this
weekend. This upper low and attendant surface cold front will be the focus
for heavy rainfall from the Mississippi Valley/Great Plains today to the
Upper Midwest on Sunday. A slight of excessive rainfall is in effect for
parts of southern Wisconsin on Sunday as a result. A much colder airmass
swoops through on the backside of the strong cold front, dropping
temperatures 20-30 degrees below average over parts of the Central
Southern Plains today before expanding into the Midwest and Middle
Mississippi Valley on Sunday.

Unsettled weather will materialize along the base of the aforementioned
upper trough today and continue into next week. Shortwave energy is
forecast to help transport a firehose of tropical moisture from the
Southeast up into the Mid-Atlantic and Midwest for the next few days.
Heavy rainfall and thunderstorms are the likely outcome across the region.
Slight risks of excessive rainfall are in effect for portions of the
Central Appalachians down into the Carolina piedmont/tidewater as well as
the Florida Gulf Coast today before the focus for heavy rain shifts into
the Raleigh-Philadelphia I-95 corridor on Sunday.

Kebede


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