004
FXUS63 KIWX 161834
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
234 PM EDT Mon Jun 16 2025

.KEY MESSAGES...

- Isolated showers and storms possible (20-30%) along and
  southeast of US 24 this afternoon into Tuesday morning.

- Additional chances (20-40%) for storms Tuesday afternoon-evening
  into areas mainly west of Interstate 69 in IN and MI.

- Thunderstorms likely (50-80%) on Wednesday, particularly mid
  afternoon through the evening when severe storms and heavy
  rainfall will be possible.

- PM peak heat indices may near 100 degrees this weekend into early
  next week.

&&

.DISCUSSION...
Issued at 234 PM EDT Mon Jun 16 2025

Mid level shear axis may activate a weak low level trough and
moisture axis for a few showers/storms later this afternoon through
Tuesday morning, mainly along and south of the US 24 corridor.
Meager shear and instability profiles should limit any isolated
storms to brief downpours and a few lightning strikes at worst late
this afternoon into early this evening.

For Tuesday afternoon and evening, convection potentially develops
over IA/nrn IL and makes eastward progress into western zones later
in the afternoon and evening. Airmass will be unstable, but any
convective activity will be outrunning more favorable flow/forcing
hinting at outflow dominant and weakening convection into mainly
western portions of the forecast area. Still could see some gusty
winds, especially if a MCV emerges with a slightly stronger wind
field than modeled.

On Wednesday, moist 70F sfc dewpoint and 1.7-2" PWAT air becomes
better established within increasing low-mid level southwest flow
preceding an approaching mid level trough and associated sfc frontal
wave. This may make for an active day locally with any lead MCS
activity and associated composite outflows supporting AM
shower/storm chances. It will be the the evolution of this activity
(cloud debris/outflow boundaries) that dictates if and when strong
to severe convection becomes a concern mid afternoon through the
evening. Low-mid level southwest flow ramps up resulting in more
favorable shear profiles by this time, with any heating leading to a
moderately unstable boundary layer along and south of any pre-
frontal features, and possibly the primary cold Wed night. Mesoscale
details are obviously uncertain 3 days out, but definitely will
continue to closely monitor as we approach this potential
severe/hydro event.

Post-frontal air mass will provide brief relief from the humidity on
Thursday with any renewed, diurnally driven, convection likely
focused off to the north with a trailing secondary mid level
impulse. Thereafter, deterministic and ensemble guidance have
remained consistent in upper ridging expanding northeast into the
Great Lakes with the warmest and most humid airmass of the season
building in this weekend into early next week. Low chances (10-20%)
that some convection could sneak in on the leading edge of the
building riding around the Friday night-Saturday periods, better
chances north.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 143 PM
EDT Mon Jun 16 2025

High levels clouds will persist into tonight with weak flow
through the mid levels and stable conditions aloft. KFWA will
experience a mid level deck just after sunrise. East southeast
winds will turn southwesterly and stay under 10 knots.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...Air Quality Alert from midnight tonight to midnight EDT
     Tuesday night for MIZ078-177-277.
MARINE...None.

&&

$$

DISCUSSION...Steinwedel
AVIATION...Frazier