780
FXUS63 KILX 030231
AFDILX

Area Forecast Discussion...Updated
National Weather Service Lincoln IL
931 PM CDT Thu May 2 2024

.KEY MESSAGES...

- Concern remains for some strong to locally severe storms through
  sunset, primarily west of I-55.

- While some quieter periods are expected during the weekend, an
  active weather pattern re-establishes itself early next week.

&&

.UPDATE...
Issued at 930 PM CDT Thu May 2 2024

Storms have diminished in intensity and coverage across central
Illinois late this evening with loss of daytime heating and the
severe threat has ended. Outflow boundaries from earlier severe
storms have gusted to near the I-57 corridor as of 925pm but the
synoptic cold front is still off to our west, likely near the
Mississippi River, but not well defined in surface obs due to the
earlier convection. A few storms remain possible over the next
several hours but mainly expect light showers through the
overnight hours.

Deubelbeiss

&&

.DISCUSSION...
Issued at 251 PM CDT Thu May 2 2024

Isolated convection has begun to fire early this afternoon near
Peoria, along a subtle surface boundary. Latest SPC mesoanalysis
shows close to 1500 J/kg of surface based CAPE across much of
central Illinois, with steep low level lapse rates of around 8.5
C/km. Already have received some pea size hail reports with the
Peoria cell. On a broader scale, numerous thunderstorms continue
to develop over central Missouri and are traveling northeast. A
general expansion northeast along the Illinois/Iowa border is
expected over the next few hours, with storms becoming numerous
over west central Illinois. Area remains in a Level 1 severe risk
this afternoon and early evening, with some brief wind/hail risks.
High-res models show some general weakening after sunset, though
PoP`s will remain high over the eastern half of the forecast area
through about 3-4 am. Timing of the overall system appears to have
sped up though, and rain chances on Friday were significantly
lowered and primarily limited to near/east of I-57.

Overall, the upper air pattern over the coming days has not
changed in the morning model suite. As the upper low over
southern Saskatchewan lifts northeast, a larger low will track
into northern California/Nevada this weekend, before ejecting into
the Plains on Monday. The international models keep the closed
low more or less intact through the period, while the GFS opens it
up for a time. Net effect of this will be periods of showers and
thunderstorms into the middle of next week. There are some signs
of extended drier periods Friday night, and again later in the
weekend, with more of an increase in PoP`s as the low moves into
the Plains and gets more wound up. Tuesday remains a period of
concern for potential for strong storms, with a number of European
ensemble members featuring CAPE values upwards of 1500 J/kg.
Overnight CSU machine learning probabilities also highlight
Tuesday as a concern.

Geelhart

&&

.AVIATION...  (For the 00z TAFs through 00z Friday Evening)
Issued at 619 PM CDT Thu May 2 2024

A cold front is approaching the Mississippi River early this
evening and will sweep across central Illinois late this evening
and overnight. Showers and storms are occurring ahead of the
front, some of which are strong to severe. Storm intensity should
wane with time but storms are likely across the terminals for a
few hours this evening before tapering off just some steady rain
for a few more hours. Winds will shift to the NW behind the front
tonight with MVFR ceilings overspreading the terminals for a
handful of hours in its wake. Conditions should return to VFR
Friday morning while winds swing around to the NNE then NE.

Deubelbeiss

&&

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

$$