Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
402 AM EDT Mon Aug 30 2021

Valid 12Z Mon Aug 30 2021 - 12Z Wed Sep 01 2021

...Hurricane IDA is forecast to slowly weaken while moving northeastward
with a Slight Risk of severe weather for tornado potential over parts of
the Central Gulf Coast through Tuesday morning...

...There is a Moderate Risk of excessive rainfall associated with IDA over
the Central Gulf Coast and Tennessee Valley that will travel along with
the IDAâ€s circulation into the Mid-Atlantic/Northeast through Thursday...

...There is a Slight Risk of severe thunderstorms over the
Northern/Central Plains and a Slight Risk of excessive rainfall over the
Middle Missouri Valley and parts of the Ohio Valley through Tuesday
morning...

...The excessive rainfall threat increases over the Southwest into the
Central Rockies as former T. C. NORAâ€S moisture moves over the region...

Hurricane IDA is slowly forecast to weaken to a Tropical Storm then a
Tropical Depression while moving northeastward into parts of the Ohio
Valley on Wednesday then into parts of the Mid-Atlantic/Northeast late
Wednesday into early Thursday morning. The SPC has issued a Slight Risk of
severe weather for tornado potential over parts of the Central Gulf Coast
through Tuesday morning. The hazard will be for isolated tornados that
will develop with the areas of heavy rain. Furthermore, the WPC has issued
a Moderate Risk of excessive rainfall with areas of heavy rain associated
with IDA. The threat of excessive rainfall will be over the Central Gulf
Coast and Tennessee Valley on Monday into Tuesday. Moderate Risk of
excessive rainfall associated with IDAâ€s circulation will travel along
the systemâ€s track as IDA moves northeastward. The threat will be over
parts of the Tennessee/Southern Ohio Valley into the Central Appalachians
on Tuesday into Wednesday morning. The focus for excessive rainfall will
move to the Central Appalachians/northern Mid-Atlantic and the Northeast
on Wednesday into Thursday morning.  The associated heavy rain will create
numerous areas of flash flooding. Furthermore, many streams may flood,
potentially affecting larger rivers along the track through Thursday
morning.

Meanwhile, a front extending from the Lower Upper Great Lakes to the
Central High Plains will move eastward, moving off the Northeast Coast and
extending across the Ohio/Middle Mississippi Valleys into the Northern
High Plains by Tuesday morning. Showers and thunderstorms will develop
along and ahead of the boundary from the Great Lakes/Northeast into the
Central Plains on Monday. Some thunderstorms will become severe over parts
of the Northern/Central Plains.  As a result, the SPC has issued a Slight
Risk of severe thunderstorms over parts of the Northern/Central Plains
through Tuesday morning.  The hazards associated with these thunderstorms
are frequent lightning, severe thunderstorm wind gusts, hail, and a few
tornadoes.

Additionally, there is a 10% or greater probability of two-inch or great
hail over the area. Finally, heavy rain will develop along different
regions of the front on Monday.  Therefore, the WPC has issued a Slight
Risk of excessive rainfall with these thunderstorms over the Middle
Missouri Valley and parts of the Ohio Valley through Tuesday morning.  The
associated heavy rain will create mainly localized areas of flash
flooding, with urban areas, roads, and small streams the most vulnerable
through Tuesday morning.

The severe thunderstorm threat will weaken slightly over the Middle
Missouri Valley on Tuesday into Wednesday morning.  Showers and
thunderstorms will continue along and near the front from parts of the
Northern/Central Plains into the Ohio/Middle Mississippi Valley on Tuesday
into Wednesday. The excessive rainfall threat will decrease slightly over
the Middle Mississippi Valley on Tuesday into Wednesday.

Elsewhere, moisture associated with what was once Tropical Cyclone NORA
will move over the Southwest into parts of the Great Basin and Central
Rockies on Tuesday into Wednesday, producing thunderstorms. Therefore, the
WPC has issued a Slight Risk of excessive rainfall with these
thunderstorms.

The associated heavy rain will create mainly localized areas of flash
flooding, with urban areas, roads, and small streams the most vulnerable
Tuesday into Wednesday morning.  Additionally, heat will also produce
hazards. Therefore, Excessive Heat Warnings are in effect over Southern
California into parts of the Southwest through Monday. In addition, the
fire weather threat has increased over the Northwest into the Northern
Rockies as Red Flag Warnings have been issued over parts of the Pacific
Northwest and Northern California as well as parts of Idaho and Wyoming.


Ziegenfelder