515
FXUS63 KILX 101115
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
615 AM CDT Fri May 10 2024

.KEY MESSAGES...
- In the Monday-Tuesday timeframe, there is a 20-30% chance of
  greater than 0.75" of rainfall in 24 hours. Should this occur,
  one impact would be additional runoff into area rivers already
  running high.

&&

.DISCUSSION...
Issued at 237 AM CDT Fri May 10 2024

An upper level wave is diving southeast across IL this morning.
There have been a few showers associated with this wave as it
traversed IA and moved into northwest IL, but the latest high res
models indicate these showers won`t make it deep into central IL.

We will see brief upper ridging this afternoon before another
upper wave dives southeast into IL tonight in the northwest flow
aloft. An associated surface low will dive southeast across the
Great Lakes with an accompanying cold front passing through IL
Friday night. We`ll see a chance for showers with this system
Friday night, but instability looks rather weak. Believe thunder
chances will be rather slim as MUCAPEs look to be less than 100
J/kg according to the HREF mean.

Expect benign northwesterly flow aloft for the weekend. We`ll have
breezy northwest winds on Saturday with a surface ridge of high
pressure moving through the area Saturday night. By Sunday night,
an upper low will be passing to the east across Ontario with a
southern stream upper low approaching to the southwest.
Precipitation chances increase across IL from this southern
system Sunday night, with some moderate chances for thunder
expected as MUCAPEs are as high as 500 J/kg in west-central IL.

The upper low will slowly make its way east across the mid MS
River Valley on Mon/Tue and the track will play a key role in how
far north the rain extends. Showers with embedded thunderstorms
are expected for the start to the week, with the southern half of
IL having the best chance for measurable rainfall. Right now, the
rainfall ensemble mean for Mon-Tue ranges from around 0.25" in
Galesburg to 0.75" in Lawrenceville. Models also have a 20-30%
chance for 0.75" of rain in 24 hrs in our southern zones, around
I-72 and south, which could add some additional runoff to area
rivers that are already running high.

Sometime in the Wed-Thu timeframe, we`ll likely see an upper
ridge move into the area once again, providing a break from the
precip for at least part of the period. There are model
differences in the timing of this ridge, but sometime on Thu or
Friday, another upper wave is expected to bring showers and storms
back to the region. Stay tuned for updates to this late week
system as the picture becomes clearer with subsequent model runs.

Knutsvig

&&

.AVIATION...  (For the 12z TAFs through 12z Saturday Morning)
Issued at 614 AM CDT Fri May 10 2024

Cigs started around 1500 ft this morning across much of central
IL...although we do have breaks that are expanding. We`ll be
seeing improvement through the morning with most areas seeing VFR
conditions by early afternoon. With our without the initial low
clouds, we should see SCT-BKN decks of cumulus develop by late
morning with bases rising to above 3000 ft AGL by early afternoon.
A few showers will move into central IL from the northwest around
03Z, but coverage is expected to be rather low so did not include
in the TAFs at this time.

&&

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

$$