Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Wed Sep 21 2022

Valid 12Z Wed Sep 21 2022 - 12Z Fri Sep 23 2022

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

...There is a Slight Risk of severe thunderstorms over parts of the Great
Basin/Northern Intermountain Region and the Lower Great Lakes/Ohio Valley
through Thursday morning...

...There is a Slight Risk of excessive rainfall over parts of the Northern
Rockies and the Great Basin/Central Rockies/Southern Rockies from Thursday
into Friday morning...

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

Tropical moisture will surge northward over the Southwest into parts of
the Great Basin/Central Rockies through Thursday. Upper-level energy will
interact with the moisture to produce shows 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, Southwest,
and Southern Rockies through 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.

Moreover, an upper-level low over Northern California/Pacific Northwest
and an associated front over parts of the Northern Intermountain
Region/Great Basin will aid in producing showers and severe thunderstorms.
Therefore, the SPC has issued a Slight Risk of severe thunderstorms over
parts of the Northern Intermountain Region/Great Basin through Thursday
morning. The hazards associated with these thunderstorms are frequent
lightning, severe thunderstorm wind gusts, and a minimal threat of hail
and tornadoes.

On Thursday, the threat of excessive rainfall decreases over the
Central/Southern Rockies. Therefore, the WPC has issued a Slight Risk of
excessive rainfall over parts of the Central/Southern Rockies from
Thursday into Friday 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. The threat of severe thunderstorms
ends over the West on Thursday, too.

Furthermore, the upper-level low over Northern California/Pacific
Northwest will stream moisture into parts of Northern California, Oregon,
and Northern Intermountain Region/Northern Rockies on Wednesday into
Thursday. The moisture will aid in producing heavy rain over portions of
the region. Therefore, the WPC has issued a Slight Risk of excessive
rainfall over parts of the Northern Intermountain Region/Northern Rockies
through Thursday 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.

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 through 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 Great Lakes 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 the Lower Great Lakes/Ohio Valley through 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/Ohio Valley
through Thursday morning. The associated heavy rain will create localized
areas of flash flooding, affecting areas that experience rapid runoff with
heavy rain.

The threat of severe thunderstorms decreases slightly on Thursday as the
front moves across the Mid-Atlantic. Therefore, the SPC has issued a
Marginal Risk of severe thunderstorms over parts of the Mid-Atlantic from
Thursday into Friday morning.

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


Ziegenfelder


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