179
FXUS63 KILX 272336
AFDILX

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

.KEY MESSAGES...

- Scattered thunderstorms (20-30% coverage) will pose a risk of
  gusty winds through about 9 PM. There is a level 1 of 5 risk of
  damaging winds.

- Tuesday afternoon/evening will also 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.

&&

.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 00z TAFs through 00z Tuesday Evening)
Issued at 636 PM CDT Mon May 27 2024

A shortwave over eastern IA, producing isolated TSRA with strong
wind gusts and isolated hail in some of these storms, will move
into the central IL terminals by around 01Z this evening. These
storms will likely weaken gradually after sunset, but the central
IL terminals could see some strong to severe thunderstorms until
02Z-03Z. Nevertheless, coverage looks to be low, so only included
VCTS for this activity and will amend if any terminals are
approached by storms. Another similar system will affect the area
Tuesday afternoon and evening. Conditions will be predominantly
VFR through the forecast period, however brief MVFR cigs/vsbys
will be possible with any storms. Winds WNW 10-15 kts with gusts
to around 20 kts, decreasing to 6-10 kts overnight. Winds
increasing to 10-16 kts with gusts 20-25 kts after 14Z.

37

&&

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

$$