Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
357 PM EDT Wed Sep 01 2021

Valid 00Z Thu Sep 02 2021 - 00Z Sat Sep 04 2021

...Post Tropical Cyclone Ida soaking northern Mid Atlantic and southern
New England with a High Risk of excessive rainfall posted into early
Thursday morning, life threatening flooding and severe weather expected...

...Rounds of severe storms and a risk of flash flooding is possible in the
Great Plains and Midwest, localized flash flooding possible in the
Southwest...

...Sultry conditions on tap in the South Central U.S., seasonally cooler
conditions across the northern tier; favorable fire weather conditions
persist in parts of California and western Nevada; poor air quality sticks
around in the West...

Post Tropical Cyclone Ida is producing significant impacts throughout the
northern Mid-Atlantic this afternoon with widespread areas of flash
flooding and severe weather. A High Risk for Excessive Rainfall remains in
place from southern Pennsylvania to southern New England. Life threatening
flooding may occur where copious amounts of rainfall accumulate this
afternoon and evening with stream and river flooding potentially lingering
into Thursday. The flash flood threat coincides with favorable conditions
for severe weather within the warm sector of Ida. The Storm Prediction
Center has issued an Enhanced Risk from the DC/Baltimore metro areas and
the northern DelMarVa Peninsula to the Lower Delaware Valley and New
Jersey coast. Post Tropical Cyclone Ida will track northeast through the
overnight hours focusing its most intense area of rainfall over eastern
Pennsylvania, northern New Jersey, and across southern New England.
Rainfall totals over 6 inches are expected with some localized areas
receiving over 10 inches by the time Ida races into the northwest Atlantic
Thursday morning. The good news-- high pressure arrives in Ida's wake
ushering in drier and seasonally cooler temperatures for the latter half
of the work-week.

The northern Mid-Atlantic and southern New England are not the only
regions witnessing eventful weather this afternoon. Strong-to-severe
thunderstorms are forecast to track across the northern Plains. A Slight
Risk for severe storms is in place for parts of South Dakota and northwest
Nebraska today as a wave of low pressure approaches from the northern High
Plains. This frontal system reaches the Midwest on Thursday where heavy
rainfall rates may lead to areas of flash flooding. For this reason, a
Slight Risk for Excessive Rainfall is in place for portions of the Upper
Midwest and Central Plains. This front will slowly inch southward by
Friday focusing the next threat for strong thunderstorms and potential
flash flooding over the central Plains. In the Southwest, remnant moisture
from Nora continue to aid in the development of heavy showers and
thunderstorms that could lead to flash flooding in spots this evening. A
Slight Risk is in place for much of the Four Corners region with Arizona,
western New Mexico, and southern Utah most at risk for flash flooding.

Temperature-wise, much of the Lower 48 will get a reprieve from
oppressively hot conditions as below normal high temps engulf much of the
northern U.S. and both the Southwest and Southeast. As the calendar flips
over to September, a brief push of September-like temperatures and comfy
humidity levels arrive in the Ohio Valley, central Appalachians, and
Northeast through Friday. The hottest portion of the country through
Friday evening will be the Southern Plains where daytime high temps
routinely soar into the mid-upper 90s. Heat indices are forecast to range
between 105-110 degrees in these areas, prompting the issuance of Heat
Advisories for much of the South Central U.S.. Additionally, there is a
fire weather threat the northern Sierra Nevada and in the Reno/Carson City
area as Red Flag Warnings have been issued in these areas. Air Quality
Alerts have also been posted in parts of the Pacific Northwest and both
the northern and central Rockies due to wildfire smoke.

Mullinax