410
FXUS63 KIWX 120458
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1258 AM EDT Fri Jul 12 2024

.KEY MESSAGES...

- Some patchy fog possible again late tonight into early Friday
  morning, especially west of Interstate 69.

- Periodic chances for showers and thunderstorms between Friday
  and the middle of next week. There is a potential of some
  strong to severe thunderstorms at times during the Sunday
  through Tuesday period.

- 90 degree high temperatures are most possible Sunday through
  Tuesday of next week, dependent on thunderstorm chances.

&&

.UPDATE...
Issued at 904 PM EDT Thu Jul 11 2024

Scattered showers and thunderstorms have diminished across most
of the area this evening with development of weak surface based
CIN. The exception is across far southwest portions of the area
where some isolated stronger showers continue in a pocket of
locally stronger low level convergence and best lingering
SBCAPEs on order of 500-1000 J/kg. While lower coverage trend
should continue through remainder of the evening, upstream flow
is highly perturbed with several short waves progressing across
the Ohio Valley and Great Lakes region into Friday. Will
maintain these low PoPs through the night with some slight
increase in coverage possible again overnight as a vort max
across the Corn Belt gets sheared into the Ohio River Valley.
With some possibility of lower cloud cover across the west, a
better source of near sfc moisture from recent rainfall, and
light winds...will add some patchy fog mention for areas west of
Interstate 69 late tonight into early Friday.

&&

.DISCUSSION...
Issued at 122 PM EDT Thu Jul 11 2024

Orphaned disturbance over nw IL caught within elongated
leftover upper troughing through the wrn lakes will slowly
liftout into ern ON by late Fri. A ribbon of sfc confluence and
weak moisture return out ahead of this sys stretches from ern IA
into cntrl IN and the focus for aftn tstorm development.

Cam solutions are fairly robust and initiate convection after
21Z far south/sw in proximity to this zone of weak convergence
which will move little if any through this aftn. Certainly
favorable destabilization underway here and will retain low chc
pops to account. Otherwise general liftout of this sys will
afford some nwd spread in weak return flow overnight of which
may prompt some shower development late toward ne IN/nw OH
similar to what was observed across nrn IL this morning.
Tomorrow sfc confluence zone expected to mix further north into
the US6 corridor and again support at least isolated storms in
the aftn timed with favorable destabilization. No severe wx is
expected either today or tomorrow in light of poor mid lvl lapse
rates, weak forcing and weak flow.

However that will all change significantly in coming days as
the plains centered thermal ridge amplifies and heats, leading
to a potentially stormy period Sun-Tue. Otherwise in tandem with
upper ridge building, a return of very warm and humid wx is on
tap.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1248 AM EDT Fri Jul 12 2024

Weak flow will persist over the area with nearly saturated
conditions at ground level at the onset. Light fog was already
forming in the FWA area (KSMD). Given conditional climatology
data and ongoing light fog formation, made some adjustments to
the visibilities at the TAF sites. Also, added VCTS at FWA given
the diurnal favorability for convection.


&&

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

&&

$$

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