Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
353 AM EDT Sat May 20 2023

Valid 12Z Sat May 20 2023 - 12Z Mon May 22 2023

...Showers and thunderstorms stretching from New England to the Southern
Plains Saturday...

...Well above average, record-breaking warmth continues for interior
portions of the Northwest through Saturday before shifting towards the
Northern Plains Sunday...

A cold front stretching from the Great Lakes southwestward through the
Ohio Valley, Lower Mississippi Valley, and the Southern Plains Saturday
morning will move southeastward towards the Atlantic and Gulf Coasts
through the weekend. Showers and thunderstorms are expected to continue
along the front from the East Coast west through the South and into Texas.
The heaviest rainfall is most likely over New England as a low pressure
system off the East Coast helps to focus moist, southerly Atlantic flow
over the region. Additional locally heavy showers will be possible over
the Tennessee Valley given favorable timing of an upper-level disturbance
aloft to help support thunderstorm development. The front will linger
Sunday from the coastal Carolinas southwest into Georgia/Florida, as well
as further west along the Rio Grande in Texas, with continued
precipitation chances. High temperatures Saturday following the passage of
the front will be below average and cool heading into late May, with 60s
and low 70s broadly from New England into the Midwest/Ohio
Valley/Tennessee Valley and as far south as the Rio Grande in west Texas.
Temperatures will be seasonably warm ahead of the front, with low 80s in
the Mid-Atlantic and mid-80s to low 90s into the Southeast. Highs will
rebound Sunday back into the mid- to upper 70s for the northern tier while
things cool over the Southeast/Carolinas into the mid-70s to low 80s.

In the West, an upper-level ridge will remain over the region with highs
for most locations running above average. Once again, the focus for the
most anomalous temperatures 15-25+ degrees above average will be over
portions of the interior Pacific Northwest, Great Basin, and Northern
Rockies/High Plains. Highs on Saturday will range from the mid-80s to low
90s, with some record-tying/breaking highs possible. An upper-level
low/associated surface frontal system will move eastward through the
interior Pacific Northwest Sunday, bringing cooler, more seasonable
temperatures in the upper 70s to low 80s. The upper-level ridge will also
move eastward, shifting the focus of above normal temperatures over the
Northern Rockies/Great Basin, as well as into the Northern Plains, where
highs will rise into the low to mid-80s Sunday. Elsewhere in the West,
highs will still generally be above average, with 80s and 90s for
California and the Desert Southwest. The one cool spot will be portions of
the Central/Southern Rockies where monsoon-like shower and thunderstorm
chances will continue through the weekend. Thunderstorm chances will also
increase for portions of the interior Pacific Northwest/Northern Rockies
ahead of the approaching upper-level trough. Anomalously high moisture
lingering over these regions will lead to some locally heavy showers, with
an isolated risk of flash flooding in terrain sensitive areas and burn
scars.

Putnam

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