727
FXUS63 KILX 122005
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
305 PM CDT Fri Jul 12 2024

.KEY MESSAGES...

- There is a level 1 severe risk for Saturday afternoon and early
  evening, mainly near and north of I-74, with damaging winds the
  main concern.

- Nighttime thunderstorm complexes to our north look to reduce
  rain prospects this far south for Sunday and Monday, though a
  cold front will bring showers and thunderstorms Tuesday.

- Heat index values over 100 degrees are likely as early as
  Saturday west of I-55, and will be widespread Sunday through
  Tuesday afternoons. Overnight heat index values may fail to drop
  much below 80 in the urban areas.

&&

.DISCUSSION...
Issued at 305 PM CDT Fri Jul 12 2024

Main forecast concerns for this package remain with thunderstorm
chances and the heat through Tuesday.

Storms:
Mostly dry weather continues for us most of the night. A shortwave
moving into the mid-Mississippi Valley early Saturday morning may
provide us with a few showers/storms in the morning, though main
convective concerns will be associated with any outflow that
pushes south out of Minnesota/Wisconsin. SPC has expanded their
Day2 level 1 risk south past I-74 on the midday update. While the
morning HREF run brings surface CAPE`s to over 3,000 J/kg in this
area by late afternoon, shear is rather marginal to support more
than an isolated severe threat.

Thunder concerns early next week mainly hinge on nocturnal
convective complexes, which the morning model suites generally
keep to our north. Thus, PoP`s have been lowered for Sunday and
Monday. Monday night looks to have more of a concerted push
southward in the storm track, as a deepening upper low swings
southeast into Ontario. This will push a surface cold front into
central Illinois by Tuesday afternoon, and into the Tennessee
Valley by Wednesday afternoon. Still some uncertainty with severe
weather prospects on Tuesday, as shear remains marginal. Once the
front goes through, the latter part of the work week looks dry, as
surface high pressure builds into the Midwest.

Heat:
Good agreement remains amongst the models on the building heat
over the next few days, as a large upper high builds east into the
Plains. 850 mb temperatures rising to around 23-24C by Monday
supports surface highs in the 90s, though ensemble spread suggests
that NBM guidance may be running a couple degrees too hot Sunday
and Monday. It has also been suggesting heat index values around
110F Monday west of the Illinois River, though the Grand Ensemble
only gives about a 45% chance of heat index 100-105 at Peoria.
Guidance dew points may also be running a tad high, as that area
missed out on the heavier rain from Beryl`s remnants and has been
on the drier side recently. We`ll still probably see a couple days
where a heat advisory is needed over at least part of the forecast
area. By Wednesday, once the front has pushed south, a few days of
relief are on tap, with highs in the upper 70s to around 80
Thursday and Friday.

Geelhart

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1231 PM CDT Fri Jul 12 2024

Scattered low clouds are over central Illinois this afternoon.
Brief periods of MVFR are possible through the afternoon into the
evening hours, but time/location are uncertain. However, for the
most part, ceilings will remain VFR. Light south-southeasterly
winds persist through the period.

Copple

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$