Excessive Heat and Heat in Illinois, July 14 to 15, 2024

Area Forecast Discussion
National Weather Service Paducah KY
1134 AM CDT Sun Jul 14 2024

.KEY MESSAGES...

- Potentially hazardous heat and humidity will begin today and
  continue into early next week. A Heat Advisory has been
  issued for all the forecast area through Monday evening.

- A potent, but slow-moving, frontal boundary will push into the
  region Tuesday night into Wednesday. Scattered to numerous
  thunderstorms are expected, with locally heavy rain and some
  flooding issues a possibility.

- Drier and much more comfortable temperatures and humidity
  levels will arrive for the second half of the week.

&&

.DISCUSSION...
Issued at 243 AM CDT Sun Jul 14 2024

Today through Tuesday night...Patchy fog will continue to
develop early this morning in this stuffy and stagnant
airmass. A few locations have already seen visibility values
drop to 1 mile or less, so may need to hoist a Special Weather
Statement or Dense Fog Advisory if conditions continue to
decline.

Today will be the start of another heat wave that will last
through Tuesday. High pressure centered over the southern
Appalachian Mountains will funnel a very warm and humid airmass
into the region. Latest NAEFS guidance shows 850 mb
temperatures climbing to 21-23C during this period, which will
yield peak surface temperatures in the lower to middle 90s in
most areas. Combined with dew point temperatures in the middle
70s (with areas near high evapotranspiration sources seeing
locally higher values approaching 80 degrees), heat index values
today, Monday, and Tuesday, should have no issues reaching Heat
Advisory criteria (105-110F) for the entire region. Low
temperatures will fall into the lower to middle 70s during this
period. Combined with the high humidity, relief from the heat
will be limited at best, especially for those in urbanized
areas.

Wednesday and Thursday...A transition to a period of unsettled
weather is looking more likely during the Wednesday and Thursday
period. Global model guidance shows a rather robust baroclinic
zone setting up over the region during this time, in association
with an approaching surface cold front from the northwest. As it
typical with summertime cold fronts, its progress will be slow
as it traverses the region. Scattered to numerous showers and
thunderstorms will develop near this boundary. Aided by
favorable upper-level dynamics, PWAT values around 2", and the
potential for training thunderstorms, locally heavy rain and
flooding issues will be possible. Latest WPC QPF now has roughly
1-2" of rain forecast over the western half (SEMO/SW IL/far W
KY) of the region, and 0.5-1.0" over the eastern half (SE IL/SW
IN/rest of W KY). Given the favorable setup, would not be
surprised if QPF amounts increase a bit more in the coming days.
Also would not be surprised by a stray strong to severe storm
with strong winds either. High temperatures will fall into the
middle to upper 80s on Wednesday and the lower to middle 80s on
Thursday.

Friday through Saturday...Following the frontal passage, a
period of very, very nice weather looks to be in store for the
region. high pressure looks to setting over the area from
Canada, bringing a refreshing break from the heat and humidity.
High temperatures will reach the lower to middle 80s, but with
very comfortable humidity levels, overnights lows look to fall
into the upper 50s to lower 60s! These values would actually not
be too far from record low territory.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1134 AM CDT Sun Jul 14 2024

A few CU around 5-6 kft AGL is possible this afternoon as
satellite imagery indicates some development across the region.
Otherwise, VFR conditions prevail through Monday morning with
only a few high cirrus clouds overnight. SWS winds today turn
light & variable tonight before increasing once again in the
morning.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Heat Advisory until 8 PM CDT Monday for ILZ075>078-080>094.
MO...Heat Advisory until 8 PM CDT Monday for MOZ076-086-087-100-
     107>112-114.
IN...Heat Advisory until 8 PM CDT /9 PM EDT/ Monday for INZ081-082-
     085>088.
KY...Heat Advisory until 8 PM CDT Monday for KYZ001>022.

&&

DISCUSSION...DWS
AVIATION...DW

Hazardous Weather Outlook
National Weather Service Paducah KY
726 AM CDT Sun Jul 14 2024

ILZ075>078-080>094-INZ081-082-085>088-KYZ001>022-MOZ076-086-087-
100-107>112-114-151230-
Jefferson-Wayne IL-Edwards-Wabash-Perry IL-Franklin-Hamilton-
White-Jackson-Williamson-Saline-Gallatin-Union-Johnson-Pope-
Hardin-Alexander-Pulaski-Massac-Gibson-Pike-Posey-Vanderburgh-
Warrick-Spencer-Fulton-Hickman-Carlisle-Ballard-McCracken-Graves-
Livingston-Marshall-Calloway-Crittenden-Lyon-Trigg-Caldwell-
Union KY-Webster-Hopkins-Christian-Henderson-Daviess-McLean-
Muhlenberg-Todd-Perry MO-Bollinger-Cape Girardeau-Wayne MO-Carter-
Ripley-Butler-Stoddard-Scott-Mississippi-New Madrid-
726 AM CDT Sun Jul 14 2024 /826 AM EDT Sun Jul 14 2024/

This Hazardous Weather Outlook is for portions of southern
Illinois, southwest Indiana, western Kentucky, and southeast
Missouri.

.DAY ONE...Today and Tonight

Dangerous heat and humidity values are forecast this afternoon.
Refer to the Heat Advisory for more details.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Dangerous heat and humidity values will continue Monday and
Tuesday. Refer to the Heat Advisory for more details.

A good chance of thunderstorms returns to the forecast late
Tuesday night through Wednesday night. Locally heavy rain may lead
to some flooding issues development. An isolated strong to severe
storm with strong winds cannot be rule out as well.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today.

DWS