Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
337 AM EDT Tue Sep 20 2022

Valid 12Z Tue Sep 20 2022 - 12Z Thu Sep 22 2022

...There is a Moderate Risk of excessive rainfall over parts of the Great
Basin/Central Rockies from Wednesday through Thursday morning...

...There is a Slight Risk of severe thunderstorms over parts of Upper
Mississippi Valley/Upper Great Lakes on Tuesday and the Lower Great
Lakes/Ohio Valley Wednesday into Thursday morning...

...There is a Slight Risk of excessive rainfall over parts of the Great
Basin/Central Rockies and the Southwest/Southern Rockies through Wednesday
morning...

...Temperatures will be 10 to 20 degrees above average over parts of the
Central Plains/Middle Mississippi Valley...

Tropical moisture will surge northward over the Southwest into parts of
the Great Basin from Tuesday into Thursday. Upper-level energy will
interact with the moisture to produce shows and thunderstorms with heavy
rain. Therefore, the WPC has issued a Slight Risk of excessive rainfall
over parts of the Great Basin/Central Rockies and the Southwest/Southern
Rockies through Wednesday morning. The associated heavy rain will create
mainly localized areas of flash flooding, with urban areas, roads, small
streams, and burn scars the most vulnerable.

On Wednesday, the most intense moisture will stream into the Southwest
into the Great Basin/Central Rockies, producing showers and thunderstorms
with heavy rain. Therefore, the WPC has issued a Moderate Risk of
excessive rainfall with these thunderstorms over the Great Basin/Central
Rockies from Wednesday into Thursday morning. The associated heavy rain
will create numerous areas of flash flooding, including burn scars.
Furthermore, many streams may flood, potentially affecting larger rivers.

Furthermore, an upper-level low off the California Coast will stream
moisture into parts of Northern California and Oregon on Tuesday,
extending into parts of the Northern Intermountain Region on Wednesday
into Thursday. The moisture will aid in producing rain over the region
with the possibility of heavy rain. Therefore, the WPC has issued a
Marginal Risk of excessive rainfall over parts of Northern California and
Oregon through Wednesday morning. In addition, the WPC has issued a
Marginal Risk of excessive rainfall over parts of Northern California, the
Pacific Northwest, and the Northern Intermountain Region on Wednesday into
Thursday morning. The associated heavy rain will create localized areas of
flash flooding, affecting areas that experience rapid runoff with heavy
rain and burn scars.

Meanwhile, a front extending across the Upper Midwest will move slowly
eastward to the Northeast Coast by Thursday. The front will trigger
showers and severe thunderstorms along and ahead of the boundary.
Therefore, the SPC has issued a Slight Risk of severe thunderstorms over
parts of Upper Mississippi Valley/Upper Great Lakes through Wednesday
morning. The hazards associated with these thunderstorms are frequent
lightning, severe thunderstorm wind gusts, hail, and a few tornadoes.

On Wednesday, the threat of severe thunderstorms moves eastward along with
the front to the Lower Great Lakes/Ohio Valley. Therefore, the SPC has
issued a Slight Risk of severe thunderstorms over parts of the Lower Great
Lakes/Ohio Valley Wednesday into Thursday morning. The hazards associated
with these thunderstorms are frequent lightning, severe thunderstorm wind
gusts, hail, and a few tornadoes.

Moreover, the possibility of heavy rain will accompany the showers and
thunderstorms over the Region. Therefore, the WPC has issued a Marginal
Risk of excessive rainfall over parts of the Lower Great Lakes from
Wednesday into Thursday morning. The associated heavy rain will create
localized areas of flash flooding, affecting areas that experience rapid
runoff with heavy rain.

Additionally, a sub-tropical upper-level high will be over parts of the
south-central portion of the country through Thursday. The sub-tropical
high will allow temperatures will be 10 to 20 degrees above average over
parts of the Central Plains/Middle Mississippi Valley. The temperatures
will be in the 90s to low 100s over the region, possibly setting records
on Tuesday.


Ziegenfelder


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