399
FXUS63 KILX 101851
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
151 PM CDT Fri May 10 2024

.KEY MESSAGES...

- In the Monday to Wednesday timeframe, there is a 30-40% chance
  for more than an inch of rainfall south of I-72, with decreasing
  chances further north. This rain will add runoff to area rivers
  already running high, increasing the risk for flooding along
  riverbanks and adjacent low-lying areas.

&&

.DISCUSSION...
Issued at 140 PM CDT Fri May 10 2024

Visible satellite shows a sea of cumulus percolating across
central Illinois, driven by surface heating and destined to perish
after its loss at sunset. Deterministic models are in agreement
500mb heights will continue their sharp rise and winds back
across the region through the evening as a shortwave ridge briefly
builds in, favoring a stable mid level atmosphere. Nevertheless,
given breaks of sunshine favoring efficient radiational warming,
mixing will be deep and surface based instability rather portly
which could lead to a brief shower/sprinkle or two, though
coverage should remain less than 15%. The better chance (> 30%
north of a Macomb to Paris line) for showers will arrive tonight
as a fast-moving, compact trough clips the northeast portion of
our area with cooling temps aloft leading to elevated instability
and low level shear increases along a trailing cold front. Between
11pm (NW of the IL River) and 4am (E of I-57), stamps on SPC`s
HREF page show various CAMs bring a narrow ribbon of
reflectivities across the area along that front, with the highest
values (and greatest chance for something to actually reach the
surface through a relatively dry atmosphere) north of I-74, where
40-60% of membership depicts measurable precip.

Behind that departing trough, another ridge will build gradually in
its wake through the weekend to foster dry and gradually warming
conditions. By Sunday, we`ll see a return to above normal temps
(normal high in Lincoln is 74 degF), though mid to high clouds will
be on the increase ahead of the next system - a cut off low
meandering our way from the Great Plains. While that feature doesn`t
properly arrive until Tuesday, moisture advection ahead of it could
lead to rain activity by late Sunday night, though this will be
delayed at least a little by the dry low level airmass in place at
that time.

Depending on the exact track of that low (and when the next system
approaches behind it), precip chances could linger through Wednesday
and possibly even into Thursday, particularly south of I-72 given
the closer proximity of the surface low`s center which the ensemble
mean tracks between Springfield, MO and Louisville, KY from Monday
night to Thursday morning. NBM suggests the same areas (south of I-
72) will have a 30-40% chance for seeing more than 1 inch of rain
for the 48-hour period ending at 12z (7am CDT) Wednesday, which will
increase run-off into rivers already running high and hence flooding
potential along riverbanks.

Bumgardner

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1254 PM CDT Fri May 10 2024

Aside from marginal MVFR ceilings around BMI (which should be
lifting over the next hour or two), VFR conditions should be
predominant throughout the forecast period, barring a brief vis
drop with scattered showers overnight. Low VFR ceilings should
break up behind the cold front, when a pronounced wind shift (from
southwest to northwest) will also occur. Northwest winds will
increase, gusting frequently over 20 kt, by mid to late Saturday
morning when surface heating aids in mixing.

Bumgardner

&&

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

$$