333
FXUS63 KIWX 131622
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1222 PM EDT Sat Jul 13 2024

.KEY MESSAGES...

* There are periodic chances (20-50%) for showers and storms tonight
  through Tuesday night. There is the potential for severe storms,
  especially later Sunday night through Tuesday.

* Hot and humid conditions are expected Sunday and Monday,
  dependent on storm coverage and timing.

* Cooler, drier weather will move in Wednesday through the rest
  of the week.

&&

.DISCUSSION...
Issued at 248 AM EDT Sat Jul 13 2024

Areas of shallow, locally dense, fog will be around early this
morning given calm winds, mainly clear skies and lingering near sfc
moisture. Story otherwise for this weekend is the increase in heat
and humidity as return southwest flow allows for a very
unstable upstream airmass to build in on the northeast fringe
of a Plains upper ridge. The leading theta-e axis does near our
far western zones later this afternoon and early evening, though
lacking convergence/forcing precludes anything more than a
10-15% PoP here with most locations experiencing a completely
dry and mostly sunny Saturday. Convection may survive southeast
into the area later tonight into Sunday morning. This occurs as
the upstream MUCAPE reservoir expands east in conjunction with
a convectively aided shortwave cresting the Plains upper ridge
into the Great Lakes. The severe threat remains low however (and
PoPs capped in the chance range) as any convective elements
outrun more favorable low-mid level flow, likely becoming
outflow dominant and in the decaying phase once reaching the
local area. West-southwest flow does deepen then into Sunday
afternoon with a lower thunder threat as a capping overspreads.
Heat indices could push the mid to upper 90s by late Sunday
afternoon, dependent on morning convection and associated
lingering clouds.

Pattern remains interesting (heat/storms) with considerable
uncertainty Sunday night through Tuesday night with impressive
low level theta-e gradient still in the vicinity under perturbed
west-northwest flow aloft. Monday likely the best potential for
near advisory level PM heat indices (near 100), though once
again dependent on the timing/track of any convective systems.
Confidence is low in these regimes, hence the broadbrush chance
PoPs and lacking details beyond the first couple of periods. An
upper trough will eventually dig into the Great Lakes sending a
synoptic scale cold front through Tuesday into Tuesday night
with additional storm chances. A comfortable/dry airmass will
settle in behind the front for the second half of the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1212 PM EDT Sat Jul 13 2024

Seemingly straightforward TAFs presented, but there are two
caveats worth noting. First, there is a low chance of patchy
ground fog once again. Wind will generally be light and copious
low- level moisture remains. However, duration was very brief
near dawn this morning and the visibility was only 3SM.

Second, showers and thunderstorms are anticipated overnight
across southern Michigan, perhaps backbuilding into far
northeast Illinois. A decaying area of storms of noted of
western WI as of this writing, which will have repercussions on
how storms evolve later today and tonight. Thus, TSRA chances,
if any, primarily at KSBN are unclear at this time.

 &&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...Air Quality Alert from midnight tonight to midnight EDT Sunday
     night for MIZ177-277.
MARINE...None.

&&

$$

DISCUSSION...Steinwedel
AVIATION...Brown