Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 141049

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
549 AM CDT Fri Jun 14 2024


- Slightly cooler and less humid conditions arrived today through
  Saturday with highs in the mid to upper 80s and lows tonight in
  the upper 50s and lower 60s.

- A prolonged period of unseasonably hot and humid weather will
  occur Sunday through much of next week. High temperatures will
  be in the low to mid 90s Sunday through Friday, with afternoon
  heat indices rising to 95 to 100 degrees, and likely surpassing
  100 degrees Monday afternoon.


Issued at 345 AM CDT Fri Jun 14 2024

An MCS had brought some severe storms to areas from I-72 north
during Thu evening with damaging wind reports most common east of
Peoria to north and east of Bloomington. Radar mosaic shows
isolated convection lingering along and south of I-72 and north of
I-70 at 345 am and tracking ESE around 25 mph. A frontal boundary
was just se of the IL river while an outflow boundary from
convection extended from St Louis to Decatur to Danville. PW
values of 1.5-1.75 inches over central parts of MO and IL helped
produce a few bands of 1-2 inches of rain over northern half of

CAMs have not been so great with handling this convection, though
HRRR appears to have best track record and it diminishes the
convection from I-72 south early this morning as it tracks into
southeast IL. Cold front to move se of Lawrence county by noon
with front pushing into central KY and southern MO by 7 pm.
Redevelopment of isolated convection during mid/late afternoon to
occur in southeast Indiana and sw MO. Mostly cloudy to overcast
skies south of I-74 early this morning, to see clouds decreasing
from north to south during today as skies trend sunny to mostly
sunny this afternoon over area. Highs today in the upper 80s with
southeast IL near 90F. Dewpoints in the mid 60s to near 70F early
today to lower into the mid 50s to near 60F during the afternoon
with north winds.

Weak high pressure over the Dakotas and MN to drift eastward
across the Great Lakes tonight and Saturday, providing fair
weather to IL. Upper level high pressure also riding into IL on
Saturday as 500 mb heights rise to 586-589 meters on Saturday.
Cooler lows tonight in the upper 50s and lower 60s with fair
skies and ENE winds less than 10 mph. Increasing mid/high clouds
on Saturday especially over the IL river valley with highs in the
mid to upper 80s. Comfortable dewpoints in the 50s to near 60F
with SE winds increasing to 10-15 mph by Sat afternoon. Lows Sat
night in the mid 60s in eastern IL and upper 60s to near 70F over
central and western CWA, mildest over west central IL toward the
MS river valley.

Convection chances appears to stay nw of central IL overnight Sat
night and Sunday as short wave trof moves into the upper MS river
valley. Best chances of thunderstorms to be over IA/WI. Meanwhile
a strong 593 dm 500 mb high strengthens over the southeast States
and breezy southerly flow on Sunday brings back heat and humidity.
Highs Sunday of 92-95 with dewpoints in the mid to upper 60s
giving afternoon heat indices in the upper 90s with western CWA
having HI`s near 100F. Mild lows Sunday night in the mid 70s, with
some lower 70s in eastern IL. Monday appears to be the hottest day
with highs of 95-98F and afternoon heat indices peaking 100-105F.
Will be close to heat advisory criteria of 105F especially over
the IL river valley. Isolated convection possible Monday afternoon
with increased deeper moisture over the MS river valley on western
side of strong upper level ridge over the mid Atlantic States.

The strong 500 mb ridge shifts into southern New England on Wed
with 500 mb heights rising toward 600 meters in southeast NY area.
The strong upper level ridge goes back into the mid MS river
valley and keeps hot and muggy conditions going through much of
next week with highs in the lower to mid 90s and afternoon heat
indices of 95 to 100F and possibly higher. The NWS Heat Risk
experimental parameters shows major to extreme levels of heat
over CWA Monday through Thu. This is an unusually long heat wave
for so early in the season for central/se IL. The "ring of fire"
around this strong upper level ridge has convection chances mainly
nw of IL though we could see isolated convection during the
afternoon and evening hours. Some signals of a weak front pushing
se into central IL next Thu night and Fri could bring better
chance of convection.



.AVIATION...  (For the 12z TAFs through 12z Saturday Morning)
Issued at 550 AM CDT Fri Jun 14 2024

Aside from patchy shallow fog with brief MVFR vsbys possible until
13Z/8 am, VFR conditions are forecast to prevail across the
central IL airports through 12Z/7 am Saturday. Few to scattered
mid level clouds with bases of 8-10k ft along I-72 until mid
morning otherwise just few-sct cirrus clouds through tonight. Any
cumulus cloud developing this afternoon occuring in southern IL.
Variable winds around 5 kts at dawn will become north at 7-11 kts
with gusts 15-19 kts after 15Z and diminish back to around 5 kts
by 01Z/sunset. NNE winds early this evening veer ENE overnight.
Very patchy shallow ground fog possible by dawn Saturday but too
limited to mention in central IL TAFs.