892
FXUS63 KILX 121422
AFDILX

Area Forecast Discussion...Updated
National Weather Service Lincoln IL
922 AM CDT Sun May 12 2024

.KEY MESSAGES...

- A pleasant end to the weekend for Mother`s Day, with 80s across
  the board this afternoon.

- Widespread rains will return on Monday and continue through late
  Tuesday. There remains a 40-60% chance for more than an inch of
  rainfall south of I-74. This rain will contribute to area
  rivers and streams already running high, increasing the risk for
  localized inundation near riverbanks. This could perhaps also
  further delay planting and inhibit germination of agricultural
  seedlings.

- Below normal temps are likely (70%) Tuesday, with chilly
  conditions Tuesday night as low temps dip into the 40s north of
  I-72.

&&

.UPDATE...
Issued at 917 AM CDT Sun May 12 2024

At 915am, surface observations showed temperatures in the upper
60s to low 70s across central and southeast IL - already up
15-20 degrees from our morning lows 3-4 hours ago. Given nearly
full sunshine, filtered only by very thin cirrus, temperatures
should continue to sharply rise through the remainder of the
morning, topping out in the low to (locally) mid 80s by mid
afternoon when surface moisture gets mixed out. Fair weather
cumulus, some towering northwest of the IL River where HREF mean
brings SBCAPE to more than 500 J/kg, will develop late morning and
build into mid afternoon to offset heating slightly, but the
shift (towards the northwest) in where CAMs put precip would
suggest none of these clouds produce precip in our area.

Bumgardner

&&

.DISCUSSION...
Issued at 253 AM CDT Sun May 12 2024

Water vapor satellite loops depict our next weather disturbance slowly
advancing across Colorado, with northwest flow aloft into Illinois
bringing Canadian wildfire smoke into the region. At the surface,
high pressure is providing light and variable winds early this
morning, which will give way to southwest flow as the surface
ridge axis shifts east of Illinois by this afternoon. Mixing of
mid-level dry air today will lower dewpoints a few degrees,
allowing for high temps to overachieve into the lower 80s across
all of central and southeast Illinois. Weak warm advection lift
this afternoon could produce spurious radar returns west of the
Illinois river, however, chances of measurable rainfall will be
low due to dry sub-cloud air. Therefore, most areas should remain
dry today.

Rain chances will ramp up after midnight tonight from southwest
to northeast, as the cutoff upper low drifts into the region.
Coverage of showers will be scattered late Sunday night and
Monday morning, with widespread rains and isolated thunderstorms
finally reaching our far eastern counties Monday afternoon.
Forecast soundings are indicating narrow CAPE profiles, limiting
updraft strength amid a weak shear environment with 25kts of 0-6km
bulk shear. Precipitable water values will climb toward 1.5"
Monday afternoon through Tuesday afternoon. The NBM is still
indicating 50-60% chance of at least 1" of rainfall for areas
south of I-74 in the Mon-Tue time frame. The Grand Ensemble has
lowered those chances a bit into the 30-50% range. Despite that,
feel that pockets of 1.5"+ inches will be in play due to high PW
values, especially south of Springfield to Mattoon.

A shortwave ridge will provide a break in the rain chances mid-
week, amid colder than normal temps in the cloudy, cold air
advection regime. Tuesday`s high temps will be limited to the mid
to upper 60s for areas north of I-70. Lows Tues night will dip
into the upper 40s north of the I-72 corridor, with steady north
winds making it feel even cooler.


Shimon

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 521 AM CDT Sun May 12 2024

VFR conditions to prevail the next 24 hours, with a general
increase in mid to high level clouds late this afternoon through
this evening. Prevailing winds will increase from the southwest
this morning, reaching around 10-12 knots by mid morning. Diurnal
winds will subside below 10 kts after sunset, as shower chances
increase for PIA and SPI toward the end of this TAF period.
However, any precip before 13/06z should be trace amounts of
rain.

Shimon

&&

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

$$