022
FXUS63 KIWX 260125
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
925 PM EDT Tue Jun 25 2024

.KEY MESSAGES...

- Uncertainties with storm redevelopment tonight. The threat for
  additional severe weather appears minimal. Better chances of
  showers and thunderstorms may hold off until late tonight or
  Wednesday morning.

- Hot weather not expected through the weekend. High will be
  mainly in the upper 70s to mid 80s.

- Next system is expected to bring chances for rain & storms
  late Friday into early Saturday night.

&&

.UPDATE...
Issued at 914 PM EDT Tue Jun 25 2024

Stable bubble and low level CIN persists across much of the area
this evening due to effects earlier convection. Main area of
thunderstorm development this evening has been in the vicinity
of very strong instability axis draped from southwest Iowa into
west central Illinois into southeast Wisconsin. Hi res guidance
trends over past few hours have backed off on extent of
convection through the early overnight locally. This trend
appears reasonable as lagging upper forcing back to the west
will likely provide little opportunity to overcome MLCIN
limitations locally. By late tonight, more substantial upper
trough should approach the western Great Lakes allowing weak low
level convergence axis to shift across eastern IL/northwest IN.
This should allow for weakening of stronger mid level lapse
rates which are aiding in capped conditions this evening. While
this may be supportive of more showers and thunderstorms,
instability magnitudes should be tempered as a result. Have
updated grids to reduce PoPs this evening into the early
overnight, but an additional decrease may be needed given
current trends.

&&

.DISCUSSION...
Issued at 252 PM EDT Tue Jun 25 2024

The initial round of storms has moved south along the outflow
boundary where convection was becoming more scattered. Large CAPE
values were indicated by SPC mesoanalysis from around 4000 to
5000 J/Kg south of the boundary from east central IL to west
central IN. Massive hail cores were indicated in this area with
70 dBz to over 30K feet per radar.

West of the forecast area over nrn IL and far southern WI, an
EML was helping to produce extremely large CAPEs in a long band
of >6000 J/Kg and a core over 6500 J/kg per SPC. Capping at the
base of the EML should hold storms in check until late this
afternoon and this evening per HRRR. Have reduced storm
coverage over the forecast area into early this evening given
the above reasoning. It still looks like a more marginal storm
threat tonight, although locally heavy rainfall is possible
along with possible subsequent flooding of mainly urban area.

Otherwise, a break in the stormy weather is expected until late
Friday when a pair of upper level systems are forecast to reach
the area per GFS. BUFKIT soundings given a strong signal for the
potential for heavy rain with precipitable. water values over
2.0 inches.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 746 PM EDT Tue Jun 25 2024

The cap has broken at the base of the EML to the west. Rather
explosive storm growth has been occurring where substantial
CAPEs were still over 4000 J/Kg. However, massive stabilization
farther east was making it difficult for storms to move east. It
looks like some upper level support later tonight will allow
storms to eventually reach the area and FWA and SBN terminals.
Have updated TAFs in this regard with a later arrival time.
There is still low confidence in this timing and further updates
are likely to be needed.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

UPDATE...Marsili
DISCUSSION...Skipper
AVIATION...Skipper