Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
359 PM EDT Tue Sep 06 2022

Valid 00Z Wed Sep 07 2022 - 00Z Fri Sep 09 2022

...Over 50 million residents are under either Excessive Heat Warnings or
Heat Advisories across the western third of the Lower 48...

...Critical fire weather over parts of the northern High Plains on
Wednesday...

...Unsettled weather and scattered flash flood chances linger over the
Mid-Atlantic and Southeast; Watching Hurricane Kay for potential impacts
in the Southwest late week...

An upper level ridge of high pressure over the western U.S. continues to
support an extensive heat dome up and down the West Coast. Following
another day of record heat on Tuesday from California to the central High
Plains, expect sizzling temperatures to stick around through mid-week.
Numerous daily record high temps are likely to be broken from the northern
Rockies and High Plains on south to southern California. The hottest
temperatures are anticipated to be in central and southern California
where daily max temps will soar as high as 110 degrees. Wednesday's
hottest temperatures compared to normal are expected to setup in the Snake
River Valley and Northern High Plains where high temperature departures
range between 20-30 degrees above normal. In addition to the stifling
daytime high temps, nighttime lows will not provide much relief as minimum
temperature departures also range between 15-30 degrees above normal. Some
relief from the searing heat finally arrives late Wednesday night into
Thursday as a cold front dives south from western Canada. 24-hour
temperature swings could be as dramatic as 20-30 degrees on Thursday in
contrast to Wednesday's oppressive heat in parts of northern Montana. The
frontal passage, however, will result in blustery winds across the
northern High Plains and northern Rockies. The combination of strong
winds, low humidity levels, and dry fuels supports the potential for
enhanced fire weather risks. In fact, the SPC has issued a Critical Risk
for fire weather in northern Montana on Wednesday with a large Elevated
Risk that spans from the Columbia River basin to eastern Montana.
Unfortunately for the West Coast, excessively hot conditions are likely to
persist into Thursday, but finally cool down to more seasonally warm
levels by the weekend.

In terms of precipitation, scattered thunderstorms continue to dot the
Southeast U.S. with lingering showers along the Mid-Atlantic coast this
afternoon. A pair of Slight Risks for Excessive Rainfall remain in place
for the Northeast coast and in the Upper Ohio Valley where there is a
heightened threat for flash flooding. There are still other areas of heavy
showers and thunderstorms as far south as the Lower Rio Grande Valley and
throughout the Lower Mississippi Valley. By Wednesday, thunderstorms will
continue to flare up from the Mid-Atlantic to the Gulf Coast due to a
frontal boundary slowly tracking across the Southeast and a pair of upper
level disturbances tracking through the Mid-Atlantic and Mid-South.
Locally heavy rainfall rates are possible within intense thunderstorms and
may result in flash flooding in these regions. As high pressure builds in
from the north, the front makes its way off the coast by Thursday leading
to drier conditions along the Mid-Atlantic coast. However, a wave of low
pressure in the Gulf of Mexico will track along the aforementioned frontal
boundary and keep unsettled weather in the forecast across the Southeast.
Elsewhere, a cold front racing across the North Central U.S. is set to
produce strong-to-severe storms across the Upper Mississippi Valley. SPC
has issued a Marginal Risk for severe weather for portions of the
Minnesota Arrowhead, northern Wisconsin, and Michigan's Upper Peninsula.
Lastly, there is the potential for Hurricane Kay to bring heavy rain and
high wind impacts to parts of southern California and the Desert
Southwest. Please visit the National Hurricane Center's website for the
latest track forecast and information.

Mullinax


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