257
FXUS63 KILX 091916
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
216 PM CDT Sun Mar 9 2025

.KEY MESSAGES...

- Dry weather with above normal temps in the upper 50s and 60s
  will prevail through midweek.

- Afternoon relative humidity values near 30% and southwesterly
  winds gusting 15-30 mph could result in heightened fire spread
  concerns Monday afternoon.

- A late week system will bring breezy winds and even warmer temps
  into the region through the latter half of the week while
  there is also an accompanying severe weather threat (15%)
  Friday.

&&

.DISCUSSION...
Issued at 208 PM CDT Sun Mar 9 2025

DRY WITH ABOVE NORMAL TEMPS THROUGH MIDWEEK...
This afternoon, the Midwest lies between an area of low pressure
digging across the Great Lakes and another area of low pressure
tracking along the Gulf Coast. Benign weather conditions will be
in place across central Illinois in between these features the
rest of today through tonight. Temps are expected to dip into the
mid 30s overnight under clear skies.

Late tonight through Tuesday, a shortwave trough will dig across
the Pacific Northwest then track along the US/Canada border.
Southwest flow will increase ahead of this feature across portions
of the mid and upper Mississippi Valley advecting warmer
temperatures into the region. Downstream of the trough, flat upper
ridging will build across the mid section of the country helping
to keep central Illinois dry and sunny. Temps will warm into the
upper 60s to near 70 area-wide Monday, and again along and south
of I-72 Tuesday. Temperatures will top out in the 50s further
north as the aforementioned shortwave trough and attendant
surface low drive a weak, dry cold front into portions of northern
and central Illinois.

Surface front will lift back north on Wednesday, but without any
upper level support and continued weak upper ridging over the
area, anticipate the front to pass through the area without any
precip. A southern stream shortwave trough will move across the
Deep South Wednesday night with precip spreading north along
portions of the lower and mid Mississippi Valley. NBM brings some
slight chance (20%) PoPs into the far southern portions of the
forecast area, but most of central Illinois will remain dry well
displaced from the upper wave.

LATE WEEK SYSTEM...
A strong upper level disturbance will dig across SoCal Thursday
and lift across the Great Plains Friday into the Upper Midwest
Saturday. The upper pattern will amplify in response to this
strong wave with upper ridging still in place over central
Illinois Thursday. Temps are expected to warm well into the 70s as
a result, with Friday shaping up to be the warmest day of the
week. While temps are forecast to top out in the mid 70s (NBM
mean) there are hints of some 80s possible Friday with NBM probs
for reaching 80F in the 25-40 percent range across central
Illinois, greatest in the west.

Meanwhile, a deep nearly 975mb surface low will move from the
Front Range of the Rockies Friday morning to the Upper Midwest
Friday night. A broad, moderately unstable warm sector is expected
to overspread much of the Mississippi Valley during the day Friday
ahead of the low. GFS/ECMWF both indicate over 1000 J/kg MUCAPE
will be in place Friday afternoon/evening with strong deep layer
shear around 50kt. LREF joint probs for SBCAPE > 500 J/kg and deep
layer shear > 30kt is 25 to 40 percent for most of the forecast
area, highest in the south. SPC currently has the 15% severe risk
over most of the forecast area, but the CSU machine learning
forecast introduces 30% probs into portions of west central
Illinois. Still plenty of time for details to be ironed out, but
this period bears close watching for a regional severe weather
risk.

Deubelbeiss

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1239 PM CDT Sun Mar 9 2025

Steady-state conditions will be in place across central Illinois
between low pressures to both our north and south. A modest
southwest breeze will prevail through the period, dropping off
below 10 kt overnight into Monday morning. VFR conditions are
expected through the period with only a few high clouds expected.

Deubelbeiss

&&

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

$$