Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
354 AM EDT Mon Jul 17 2023

Valid 12Z Mon Jul 17 2023 - 12Z Wed Jul 19 2023

...Lengthy heat wave to continue in the Southwest, South Central U.S., and
South Florida...

...Severe storms and bouts of heavy rain to occur from the Nation's
Heartland to the Ohio Valley and Northeast through Tuesday...

...Canadian wildfire smoke responsible for Air Quality alerts over parts
of the Northern High Plains, Midwest, Great Lakes, and Northeast...

The upper level ridge of high pressure responsible for the heat wave in
the West will begin to give way over the Northwest, but expand across the
Southwest and Gulf Coast states through mid-week. Record breaking heat is
expected each day through mid-week in the Four Corners states, from Texas
to the Lower Mississippi Valley, and South Florida. Daytime highs will
routinely reside in the triple digits in the Desert Southwest and deep in
the heart of Texas. Farther east, the Gulf Coast and Mid-South can expect
daytime highs in the mid-upper 90s that coincide with oppressive dew
points, resulting in sweltering heat indices between 105-115F. In
addition, daily low temperatures will remain remarkably warm, breaking
record warm daily minimums in many cases. This means little in the way of
relief for areas desperately needing to cool off from the sizzling daytime
highs. There remain an expansive area of Excessive Heat Warnings and Heat
Advisories in the Southwest, Southern Plains, western Gulf Coast, and even
parts of South Florida where exceptionally warm sea surface temperatures
are playing a role in the prolonged stretch of sultry heat. Please visit
heat.gov for more information on impacts from the heat wave. Elsewhere,
the Northeast and Mid-Atlantic will continue to see hot and humid
conditions through Tuesday. Meanwhile, a cold front will provide the
Midwest and Great Lakes with cooler than normal temperatures. Some
locations in the Upper Midwest will struggle to get out of the 70s for
highs both Monday and Tuesday.

Focusing on areas with unsettled weather, numerous showers and
thunderstorms will engulf portions of the Midwest, Ohio Valley, Northeast,
and Florida through Tuesday. Today, strong-to-severe storms will ignite
along a lengthy frontal boundary that spans from the northern High Plains
to the Ohio Valley. The Storm Prediction Center (SPC) issued a pair of
Slight Risks (threat level 2/5) in the lower Ohio Valley and northern
Plains while the Marginal Risk (threat level 1/5) stretches from the Snake
River valley to western Pennsylvania. When it comes to possible Excessive
Rainfall, the Weather Prediction Center has a handful of Marginal Risks
(threat level 1/4) in the Midwest, Ohio Valley, northern Mid-Atlantic, the
eastern coast of Florida, southern Louisiana, and southern Arizona, as
thunderstorms in these areas could cause flash flooding. By Tuesday, the
threat for Excessive Rainfall become heightened over the Northeast as a
cold front approaches from the west. The combination of torrential
rainfall rates and overly saturated soils has resulted in a Slight Risk
(threat level 2/4) that stretches from the NYC metro on north into
northern New England. Both WPC and SPC have Slight Risks for parts of the
Middle Mississippi Valley and Lower Ohio Valley where storms could produce
damaging wind gusts, large hail, and flash flooding. WPC's Excessive
Rainfall Outlook also shows a Marginal Risk in parts of the Upper Midwest
and again in southern Arizona.

Canadian wildfire smoke will remain in the picture through Tuesday as
northwesterly winds aloft that originate out of the Canadian Prairies
continues to direct more smoke into the Lower 48. There are Air Quality
alerts issued for areas the include the northern High Plains, the Midwest,
Great Lakes, central Tennessee and North Carolina, and into the Northeast
where higher concentrations of smoke will result in unhealthy air quality
for sensitive groups. Smoke concentrations should diminish over parts of
the Heartland on Tuesday, but may still cause poor air quality along the
East Coast.

Mullinax


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