Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
325 PM EDT Wed Jul 20 2022

Valid 00Z Thu Jul 21 2022 - 00Z Sat Jul 23 2022

...Dangerous heat to continue impacting much of the central and
northeastern United States...

...Severe thunderstorms possible across the Ohio Valley this evening
before shifting into New England and parts of the Southeast on Thursday...

...Persistent monsoonal moisture to bring locally heavy rains and isolated
flash flooding across portions of the Southwest into the southern
Rockies...


Heat continues to be the major weather story heading into the latter half
of the week, with over 100 million citizens currently located within
Excessive Heat Warnings and Heat Advisories. Even though it is mid-July
and during the climatological peak of summer for most locations, well
above average temperatures are making conditions even more likely to cause
heat related illnesses. A strong upper-level ridge that has dominated the
weather pattern over the last several days continues to remain situated
over Southwest and is forecast to stretch eastward by Friday. Widespread
high temperatures in the mid-to-upper 90s and low 100s will encompass a
majority of the country on Thursday and Friday. Relatively cooler weather
is expected to be confined to the immediate West Coast and Great Lakes,
where highs should reach into the 70s and 80s. Areas most are risk for
dangerous heat will be located across the Southwest, Great Basin, central
and south-central U.S., coastal Mid-Atlantic, and Northeast. Highs in
these locations will near or exceed 100 degrees, with humidity east of the
Rockies making it potentially feel closer to 110 degrees during the late
afternoon hours. Low temperatures will also remain quite warm and only
drop into the upper 70s and low 80s, possibly breaking dozens of daily
warm minimum temperature records on Thursday morning. The scorching heat
during the day combined with warm overnight temperatures can make
conditions particularly dangerous for anyone spending extended time
outdoors or without air conditioning. Residents within an Excessive Heat
Warning or Heat Advisory are advised to follow proper heat safety and
check in on anyone who may be more vulnerable to heat related illnesses.

A cold front traversing the lower Great Lakes tonight will spark scattered
thunderstorms across the Ohio Valley and into the central/southern
Appalachians. Some storms may turn severe, producing damaging wind gusts,
large hail, and isolated tornadoes from southeast Michigan to Kentucky.
There is also the potential for thunderstorms to contain intense rainfall
rates and repeat over parts of eastern Kentucky and adjacent areas. A
Slight Risk (level 2/4) of excessive rainfall is in effect for this area
through early Thursday morning. As the cold front progresses eastward on
Thursday, the severe weather threat is anticipated to shift toward New
England and farther southward into the Southeast. Damaging wind gusts and
isolated hail should remain the primary hazard, with isolated tornadoes
also possible across New England. A Slight Risk (level 2/5) of severe
weather has been issued for Thursday across New England, as well as an
area extending from central North Carolina to central Mississippi.
Additionally, heavy rainfall within these thunderstorms could lead to a
localized flash flood threat.

Elsewhere, monsoon season is expected to continue across the Southwest and
into parts of the central Great Basin/Rockies. Isolated thunderstorms
forming during the afternoon and persisting into the evening will continue
to be a daily occurrence, but overall areal coverage to shrink a bit into
Thursday and Friday. Showers and thunderstorms are most likely to impact
Arizona, New Mexico, and Colorado during this timeframe. Areas near recent
burn scars, slot canyons, and saturated vegetation are most at risk to
localized flash flooding.

Snell

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