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FXUS63 KILX 280443
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1143 PM CDT Mon May 27 2024

.KEY MESSAGES...

- Tuesday afternoon/evening will feature scattered storms (20%
  coverage) capable of gusty winds.

- High pressure takes control for the latter half of the week,
  with mild and dry weather Wednesday into Friday.

&&

.UPDATE...
Issued at 857 PM CDT Mon May 27 2024

A shortwave trough over the area coincident with up to 500 J/kg
MLCAPE and around 30 kt effective bulk shear continues to produce
isolated to scattered thunderstorm coverage this evening. Overall
convective trends are weakening, and estimate storms should no
longer be capable of half inch hail/gusty winds to 50 mph by 10
PM. Have extended slight chance thunderstorms over the area to 11
PM. Otherwise, lows in the mid 50s, with WNW winds 5-10 mph and
gradually clearing skies looks on track

37

&&

.DISCUSSION...
Issued at 228 PM CDT Mon May 27 2024

Shortwave trough was digging into southern MN this afternoon.
Airmass ahead of it was much drier than recent days (PWAT 0.66"
upstream on DVN 12z sounding), but large scale ascent and steep
low to mid level lapse rates were producing a broken arc of
showers and storms from southern MN to northern MO. These will
track southeast across much of the CWA north of I-70 between 5-9
pm before fading with the loss of diurnal heating. Sufficient
instability and shear will combine with dry low levels/high LCLs
(inverted-v soundings below 850 mb) to bring an isolated damaging
wind and hail risk with the stronger updrafts early this evening.
Overall coverage of storms will be low, and continue to advertise
20-30% PoPs.

Tomorrow, another shortwave with similar strength/track/timing,
will bring another round of isolated late afternoon to early
evening showers/storms. Surface temperatures look to be a few
degrees cooler and LCLs are a bit lower, though a dry sub-cloud
layer will favor more gusty downdrafts in the stronger cells.
Can`t rule out an isolated near-severe gust but overall the
coverage and intensity should be a tick lower than today.

Wednesday into Friday, a progressive upper level pattern features
troughing deepening over the northeast U.S., while sharp but
narrow ridging presses east from the Plains. This looks to bring a
quiet stretch of weather with below normal temperatures (some lows
dipping into the upper 40s Wed/Thu nights), though moderating by
the end of the week.

Late Friday into early next week, a more active zonal flow sets up
across the Midwest. This would favor warmer/slightly above normal
temperatures as heights rise toward the end of the forecast, and
at least a few periods of showers and storms. Ensemble data
suggests the upper jet retreats north, which may limit organized
severe risks, though instability increases through the weekend.
CSU-MLP and CIPS analogs show any low end severe risks remaining
well off to our southwest over the Plains where higher instability
resides.

25

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1143 PM CDT Mon May 27 2024

VFR conditions expected over the central IL terminals overnight,
then a shortwave will propagate across central IL Tuesday
afternoon/evening to produce isolated TSRA with strong wind gusts
from around 21Z-02Z. Have included VCTS in TAFs since coverage
will be isolated and exact timing of individual storms is
uncertain at this time. Conditions will be predominantly VFR
through the forecast period, however brief MVFR cigs/vsbys will be
possible with any storms. Winds WNW 5-10 kts overnight,
increasing to 10-16 kts with gusts 20-25 kts after 14Z. Winds
decreasing again after 01Z-02Z.

37

&&

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

&&

$$