249
FXUS63 KILX 051935
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
Issued by National Weather Service St Louis MO
235 PM CDT Thu Jun 5 2025

.KEY MESSAGES...

-Despite daily rain chances through Monday, most of central
 Illinois will experience below normal rainfall over the next 7
 days. The exception will be in areas near and south of I-70 where
 there is a chance (30-50%) for above normal rainfall. Normal
 rainfall this time of year is about 1 inch per week.

-Temperatures are trending slightly below normal over the next 7
 days with afternoon highs generally in the 70s and overnight lows
 around 60. The normal high this time of year is around 82 F.

-Any storms that do develop between now and Monday have a low
 risk (< 5% probability) of severe weather and/or flash flooding.


&&

.Discussion... (Through next Thursday)
Issued at 233 PM CDT Thu Jun 5 2025

Choppy mid-level, zonal flow will support daily chances for rain
through Monday across portions of central and southeast Illinois.
The coverage of such activity looks to be confined to areas near
and south of I-70 on Friday, then areawide Saturday, Sunday and
Monday. On the synoptic scale, any showers and storms that develop
Friday and Saturday will be tied to a shortwave impulse and its
attendant sfc low pressure (if not decaying MCV) that will ride
along a diffuse baroclinic zone. The Sunday activity will be
driven by a weak synoptic cold front that slumps across the region
later in the evening. And then any showery activity that bleeds
into Monday afternoon will be scattered, stratocu-type rain on the
backside of a departing upper-level low. On the whole, CAPE/Shear
profiles during this stretch appear underwhelming and not
supportive of severe weather. The sneaky exception could be Friday
and Saturday afternoon, particularly if a squirrelly MCV does in
fact traverse our southern counties.

The rain chances and associated cloud cover should keep a
downward pressure on temperatures through early next week, with
NBM guidance offering afternoon temps in the 70s and overnight
lows around 60. Certainly we will breach 80 in a few spots during
this stretch given a favorable summer sun angle, but it should be
the exception and not the rule.

A brief stretch of dry and seasonably hot weather is apparent
among blended (NBM) and ensemble guidance (LREF) for Tuesday and
Wednesday. By then, the upper low will begin to open and lift out
of the Great Lakes region, and a ridge of surface high pressure
will build across the central US. A little bit of noise creeps
back into the guidance by Thursday, with some (GEFS) signaling a
return of rain while others (EPS/GEPS) fade it.

MJA

&&

.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1228 PM CDT Thu Jun 5 2025

The area is currently split between clear skies in the north and
MVFR stratus/stratocu in the south. We`ll see some mixing out of
the clouds along the clear/cloudy boundary, but guidance is in
consensus that the south will generally stay socked in while high
clouds move in across the area this afternoon. That should hold
through the evening and overnight, and with current dewpoint
depressions at 5 degrees or less for most areas under the clouds,
it appears likely that we`ll see another round of fog and low
stratus in the early morning hours. Guidance favors this the most
strongly at DEC and CMI, with SPI and BMI on the periphery of the
MVFR/IFR countdowns, and PIA remaining VFR through the night. I
think there`s a reasonable chance that PIA also goes down to at
least MVFR around sunrise tomorrow, but I`ve stuck pretty close to
the model forecast for the time being given that dewpoints are
mixing out more effectively at PIA.

BSH

&&

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

$$