Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
355 PM EDT Thu Jul 27 2023

Valid 00Z Fri Jul 28 2023 - 00Z Sun Jul 30 2023

...Dangerous heat wave to continue across the Northeast and Central &
Southern Plains, lasting through weekend...

...Severe thunderstorms and flash flooding possible throughout portions of
Northeast on Thursday...

...Record-breaking heat to continue across Southwest and Central U.S.
through end of week...

Widespread heat is expected to impact millions as a dangerous heat wave
materializes over the Plains and East Coast during the latter part of this
week. Currently, Excessive Heat Advisories and Warnings are in effect over
the Mid-Atlantic, Northeast, lower Great Lakes, and much of the Great
Plains. Within these areas, daytime temperatures are forecast to approach
and exceed 95-100F heading into this weekend, but oppressive humidity will
make these temperatures feel much hotter. Heat index values are set to
approach 105-110F on Thursday and Friday, especially over the Mid-Atlantic
and Central Plains. In addition to the hot daytime highs, nighttime lows
are also expected to be 10 to 15 degrees above average, with the potential
for several warm nighttime low records to be broken. Some areas may not
see their heat indices drop below 80 degrees overnight. Residents that are
under heat-related advisories and warnings should practice heat safety
this week as this heat wave will be the hottest stretch of summer so far
for many. Heading into this weekend, the orientation of heat is expected
to shift; an upper-level ridge will amplify over the Central Plains,
resulting in the continuation of hot weather over the central U.S. On the
contrary, relief is expected to arrive in the Northeast and Mid-Atlantic
over the weekend as a cold front ushers in much cooler and drier air over
the weekend. High temperatures expected to maximize in the low to mid 80s
over the region by Sunday.

While much of the country will be experiencing hot weather, other parts of
the country will be experiencing severe weather. In the Northeast, an
upper-level shortwave will help to force an area of severe thunderstorms.
The Storm Prediction Center has highlighted an area with a Slight Risk of
Severe Thunderstorms (level 2/5) over the Northeast Corridor, noting the
potential for strong wind gusts and an isolated tornado or two.
Additionally, anomalously high moisture content across the region may set
the state for possible flash flooding across New England. WPC has issued a
Slight Risk of Excessive Rainfall (level 2/4) across this region, noting
the potential for thunderstorms to produce heavy rain rates over highly
saturated soils from previous heavy rainfall.

A second area of strong thunderstorms is expected to impact the Upper
Midwest along a cold front seeping through the region. A very unstable
airmass is expected to develop during the afternoon, and these two
features will positively interact to produce an area of severe
thunderstorms over Minnesota. This complex of thunderstorms will move
east-southeastward through portions of Wisconsin overnight. The Storm
Prediction Center has issued an Enhanced Risk (level 3/5) for Severe
Thunderstorms over the region, as these thunderstorms may have the
potential to produce damaging wind gusts very large hail. Over the
following days, daytime convection is expected to form along the cold
front sweeping through the Great Lakes, which will provide some relief
from summer heat across the northern tier of the country.

Elsewhere, an upper-low off the coast of Florida is producing an area
heavy rain and thunderstorms across much of the Florida Peninsula,
especially southeast Florida. WPC issued a Slight Risk of Excessive
Rainfall across the region given urban sensitivity to flash flooding in
southeast Florida. This upper-low is expected to drift into the Western
Atlantic by Friday, helping to lessen the heavy rain threat. Over the
West, the heat wave continues, with above-average temperatures persisting.
Several locations are set to near record highs and record warm lows in the
short term forecast. Additionally, daily scattered diurnal showers and
thunderstorms forecast across the region, especially over areas of complex
terrain.


Genz

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