Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
340 AM EDT Sun May 21 2023

Valid 12Z Sun May 21 2023 - 12Z Tue May 23 2023

...Severe storms possible across portions of the Northwest and the
Northern Rockies Sunday...

...Northern Plains heats up heading into next week as temperatures across
much of the West remain above average...

...Precipitation chances and below average temperatures linger through
much of the South...

An upper-level trough off the northwest Pacific coast will push a cold
front eastward through the interior Northwest and into the Northern
Rockies over the next couple days, keeping storm chances trending up and
bringing an end to the much above average temperatures that have lingered
over the region for much of the past couple weeks. The Storm Prediction
Center has outlined a Slight Risk (level 2/5) of severe weather as cooling
temperatures aloft with the approaching trough overspread warm surface
temperatures ahead of the cold front, leading to robust storm updrafts
capable of producing large hail. Anomalously high moisture in the region
may also lead to some heavy downpours, and some isolated instances of
flash flooding are possible, particularly around terrain sensitive areas
and any burn scars. Highs will remain in the mid-80s to low 90s ahead of
the front Sunday before temperatures across the region settle into the
mid-60s to mid-70s Monday.

Meanwhile, stubborn upper-level ridging that has been in place over the
West will shift eastward a bit, bringing the focus of the much above
average temperatures that have been noted across the interior
Northwest/Northern Rockies east into the Northern Plains. Highs have
already been warming up over the Northern High Plains, with low to mid-80s
forecast Sunday. Highs will soar into the low 90s on Monday, with mid-80s
spreading eastward over the Northern Plains. Temperatures will also remain
above average over southern portions of the interior West outside of the
influence of the upper-level trough. Highs will range from the mid-80s in
the Great Basin to the 90s in the Central California Valleys and the low
100s in the Desert Southwest. Coastal California will be cooler in the
60s.

High pressure will settle in over the Midwest/Northeast following the
passage of a cold front pushing off the East Coast. This will keep
precipitation chances low and temperatures mild, with highs forecast in
the 70s to low 80s. Further south, the frontal boundary will linger over
portions of the Southeast/Florida, bringing daily thunderstorm chances.
High moisture pooling along the boundary will lead to some locally heavy
rainfall, with repeated rounds of storms possible in the vicinity of the
boundary. This may lead to a few isolated instances of flash flooding.
Further west, a weak wave aloft embedded within the large-scale
upper-level ridge will help to trigger shower and thunderstorms for
portions of the Central/Southern Rockies and into the Southern Plains
Sunday-Monday. As in the Southeast, high moisture content lingering in the
region as well as slow-moving/clustering storms may lead to some locally
heavy rainfall and isolated flash flooding concerns. Temperatures will
remain below average for late May across much of the region following the
passage of the front, with highs in the upper 70s to low 80s. Conditions
will be warmer closer to the Gulf Coast, where highs will be in the upper
80s to low 90s.

Putnam

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