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624
FXUS63 KILX 151738
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1238 PM CDT Sat Jun 15 2024

.KEY MESSAGES...

- An extended early season heat wave is on tap for the upcoming
  week, starting Sunday. Heat index values will rise into the
  upper 90s to near 100 Sunday afternoon, reach 100 to 105 on
  Monday afternoon, and be in the middle to upper 90s for the
  remainder of the week.

&&

.DISCUSSION...
Issued at 400 AM CDT Sat Jun 15 2024

Predawn surface map shows 1023 mb high pressure over east central
Ontario Province and ridging sw into WI, eastern IA and nw IL.
Clear skies/fair weather prevailed over central and southeast IL,
while blowoff of mid/high clouds over nw IL just north of CWA
from MCS in eastern Nebraska and northeast KS. Temps were in the
upper 50s/lower 60s at 3 am, ranging from 55F in Robinson to 65F
in Peoria. Comfortable dewpoints ranged from 52-58F over CWA.

High pressure to drift into the eastern Great Lakes by sunset
while ridging back toward eastern IL. Meanwhile upper level
ridging into IL today with 500 mb heights of 586-589 dm.
Some passing bands of high clouds over the IL river valley gives
partly to mostly sunny skies today while ample sunshine over
southeast IL. Convection over the central plains ahead of a short
wave trof to lift ne into the upper MS river valley today. Mostly
models keep qpf nw of CWA, though GFS model is outlier with some
qpf as far se as the IL river valley overnight. Will still need to
watch Knox and Stark counties which will be closest to this
convection chances. Highs in the upper 80s today with comfortable
dewpoints still in the 55-60F range with SE winds 5-15 mph. Lows
tonight in the mid 60s eastern IL and around 70F over western CWA.

Warm front to move east toward the IL/MO border by dawn Sunday and
sweep quickly eastward through central/se IL during Sunday
morning, while strong upper level ridge builds over the Southeast
States. Most models have this front passing through CWA as dry
and kept a dry forecast on Sunday. Breezy SSW winds develop on
Sunday in warm sector increasing heat and humidity. Highs in the
low to mid 90s Sunday with dewpoints rising to 65-70F giving
afternoon heat indices in the upper 90s to near 100F. Muggy lows
Sunday night in the mid 70s, with some lower 70s near the Indiana
border.

Strong 500 mb ridge with 595 dm high shifting northward into the
mid Atlantic States on Monday. Some deeper tropical moisture
lifting NNE from central/western Gulf of Mexico into mid MS river
valley and possibly as far north as central/se IL could produce
isolated convection Monday afternoon until dusk Mon evening.
Monday to be even hotter with highs in the mid 90s and some upper
90s possible over IL and Wabash river valleys with breezy SSW
winds. Heat indices peak from 100-104F Monday afternoon. This will
be approaching heat advisory criteria of 105F plus extended
period of early season heat this upcoming week may eventually need
heat headlines over area. A fair amount of sunshine in central IL
monday with partly to mostly sunny skies in southeast IL where
more cumulus clouds to develop.

Very strong 500 mb high of 598-600 dm into the upper mid Atlantic
coast area and southern New England by Wed and likely continues
the heat wave over IL much of the week. Continue stream of
tropical moisture from gulf into IL on Tue and have 20-30% chance
of showers/thunderstorms especially Tue afternoon. Partly to
mostly cloudy skies on Tue and partly sunny skies Wed with highs
around 90F to lower 90s. Heat indices in the low to mid 90s Tue
and Wed afternoon. An approaching cold front nearing the IL/IA
border on Wed to bring better chance (30-40%) of convection to
the IL river valley by Wed afternoon with slight chance in
eastern/se IL Wed afternoon.

Strong upper level ridge anchored over the mid Atlantic States
much of the week and builds back into IL on Thu-Saturday with
temps getting back into the low to mid 90s and afternoon heat
indices in the mid 90s to near 100F. Models differ on "ring of
fire" with convection around peripheral of upper level ridge. GFS
has convection further se into central IL Wed-Fri while Ecmwf and
GEM models keeping convection chances more isolated at times or
even nw of area. Stayed with NBM low pops with chances pops at
times northern/nw CWA during 2nd half of next week.

Climate Prediction Center (CPC) 8-14 Day for June 22-28 has 60-70%
chance of above normal temperatures over IL. CPC Week 3-4 outlook
for June 29-July 12 continues 60-70% chance of above normal
temperatures over IL. So summertime heat is favored to continue
next few weeks over the area.

07

&&

.AVIATION...  
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(For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1238 PM CDT Sat Jun 15 2024

VFR conditions will prevail through the entire 18z TAF period.
BKN-OVC high clouds will stream across the sky through this
afternoon, then will thin/dissipate toward sunset. As boundary
layer moisture flows northward and surface dewpoints increase,
NAM Cu-rule suggests SCT diurnal Cu development at around 5000ft
after 14z Sun. Winds will initially be SE at 5-10kt, then will
become S/SW and gust 18-22kt by mid-morning Sunday.

Barnes
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&&

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

$$