Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 PM EDT Wed Sep 20 2023

Valid 00Z Thu Sep 21 2023 - 00Z Sat Sep 23 2023

...Below-normal temperatures expected across much of the western U.S.,
with widespread precipitation over the northern Intermountain West and
Rockies...

...Increasing chance for strong to severe storms and heavy rain over
portions of the northern and central Plains on Friday...

...Strong to severe thunderstorms and heavy rain expected for portions of
the southern Plains on Thursday...

...Gusty winds, heavy rain, and high surf likely for portions of the
Southeast and southern Mid-Atlantic late this week...

A deep upper-level low developing over the Northwest today is forecast to
sink slowly south over the next day before drifting east later in the
week.  This system is expected to bring widespread precipitation to the
Intermountain West and northern Rockies, with below-normal temperatures
spreading across much of the western U.S.  A Freeze Watch is in effect for
portions of northwestern California and south-central Oregon, where
widespread areas of subfreezing temperatures are possible east of the
Cascades tonight into Thursday morning.  A Red Flag Warning is in effect
farther to the southeast, including the northern Sacramento Valley, where
gusty winds and low humidity are expected beginning tonight and continuing
into Thursday.

Over the northern into the central Plains, showers and thunderstorms are
forecast to focus near a slow-moving frontal boundary through the period,
with the threat for organized heavier precipitation increasing by Friday
as the system in the West begins to drift east.  Also increasing will be
the threat for severe weather, with scattered strong to severe storms
capable of large hail, damaging winds, and perhaps a couple of tornadoes
expected across portions of the central Plains on Friday.

Over the southern Plains, an upper level disturbance interacting with a
moist airmass along a slow-moving boundary will support showers and
thunderstorms over the next couple of days, with an increased chance for
strong to severe storms and heavy rainfall on Thursday across portions of
southern Oklahoma and North Texas into the ArkLaTex region.  Damaging
winds and hail, along with heavy rainfall resulting in flash flooding are
possible across this area.

In the East, high pressure is forecast to prevail across much of the
region through late Friday.  The primary exception will be  along the
Southeast and southern Mid-Atlantic coasts.  This region will likely be
impacted by a non-tropical low pressure system that is forecast to develop
east of the Florida peninsula within the next day or two.  This system
could acquire some subtropical characteristics as it track north on
Friday.  Regardless of development, this low is likely to bring gusty
winds, heavy rain, and high surf to portions of the Southeast and
Mid-Atlantic states late this week.

Pereira

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