Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
149 PM EDT Mon Jul 29 2024

Valid 00Z Tue Jul 30 2024 - 00Z Thu Aug 01 2024

...Flash flooding possible in the Ohio/Tennessee Valleys and
central/southern Appalachians early this week...

...Scattered severe thunderstorms and heavy rain forecast across portions
of the Northern Plains and Midwest...

...Dangerous mid-summer heat wave to expand across the Central U.S. and
Southeast...

Bouts of thunderstorms are expected to continue over portions of the
Ohio/Tennessee Valleys and spread further into the central/southern
Appalachians to start off the work week. An active upper-level pattern
featuring at least a couple shortwaves and an approaching surface frontal
system from the west will help to focus storm development over the
Ohio/Tennessee Valleys and eventually into the southern Appalachians
through tonight. Plentiful moisture in place will also continue to lead to
the threat of heavier rain rates, with increasing storm coverage into the
evening and potential back building/repeated rounds of storms raising the
chance for locally heavy rainfall totals. As such, a Slight Risk of
Excessive Rainfall (level 2/4) is in place for the threat of some
scattered flash flooding. In addition, sufficient instability/shear will
be in place over the Ohio Valley for a couple more intense storms, as well
as the threat for a more organized storm complex later this evening. The
Storm Prediction Center has included a Slight Risk (level 2/5) for severe
weather as well mainly for the threat of damaging winds. A similar pattern
will be in place on Tuesday, with the focus shifting further into the
southern and central Appalachians as the upper-level energy and surface
frontal system move eastward. Another Slight Risk of Excessive Rainfall is
in effect here for additional instances of flash flooding. Outside of the
flash flooding threat, scattered thunderstorms with moderate to locally
heavy rainfall are expected more broadly over the Midwest/Southeast
Monday. Rain chances will expand over the Mid-Atlantic/Northeast as the
system approaches from the west on Tuesday. Forecast high temperatures
across the East will vary depending on cloud/storm coverage, with mostly
mid-80s to low 90s expected.

Some additional storms will be possible further west along the frontal
boundary into the Upper Midwest and Northern Plains. Embedded upper-level
energy will help to trigger one round of storms over the Northern Plains
today. Stronger upper-level flow will lead to more deep-layer shear here
than further east, with another Slight Risk of severe weather for the
threat of some very large hail as well as significant damaging winds if
storms consolidate/grow upscale into an organized system later in the
evening. Another round of severe weather is possible downstream over the
Upper Midwest Tuesday as yet another upper-level impulse helps to trigger
storms along the frontal boundary. Very high moisture will lead to strong
to extreme instability, with a Slight Risk in place for the chance of more
damaging winds.  

Outside of the severe weather threat, heat will become the big story more
broadly over the central U.S. over the next few days as an upper-level
high strengthens/expands over the region. Forecast high temperatures
Monday and Tuesday are expected to soar into the triple digits over the
Central Plains, with upper-90s to low 100s to the west over much of the
High Plains, and mid- to upper 90s for the Middle and Lower Mississippi
Valley. High humidity values over the Mississippi Valley and eastern
portions of the plains will lead to heat indices in the 105-110 degree
range, potentially as high as 115 for some locations, with widespread
heat-related warnings/advisories in place. Warm morning lows only dropping
into the mid- to upper 70s will provide little relief from the heat
overnight. This combination of hotter temperatures to the west, higher
heat indices to the east, and the multi-day duration of this heat wave
will increase the danger not only to more sensitive groups, but also the
general public, particularly those without adequate air conditioning. 

A stagnant troughing pattern over the West will keep temperatures mostly
below average across the region, especially over portions of the Pacific
Northwest and northern Great Basin/Rockies. Forecast highs Monday-Tuesday
range between the 60s and 70s along the Pacific Coast, the 70s and 80s in
the Pacific Northwest and northern Great Basin/Rockies, the 80s and 90s
for interior California and the central Great Basin/Four Corners Region,
and 100s in the Desert Southwest. A cold front passing through the Pacific
Northwest will bring some rain chances on Monday, spreading into the
northern Rockies Tuesday. Smoke from area wildfires will also continue to
plague parts of the West, particularly over portions of the northern Great
Basin, resulting in poor air quality and areas of reduced visibility. 

Putnam/Snell

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