220
FXUS63 KIWX 291648
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1248 PM EDT Sat Jun 29 2024

.KEY MESSAGES...

- Showers with scattered storms today; some storms may be
  severe with strong to locally damaging winds and heavy
  rainfall.

- Dry, cooler & less humid Sunday and Monday. Highs in the 70s.

- Very warm Tuesday through Thursday (July 4th) with highs in the
80s to around 90. Chances for showers and storms each day.

&&

.DISCUSSION...
Issued at 313 AM EDT Sat Jun 29 2024

A very moist airmass was over the area with precipitable water
values topping 2.0" per SPC mesoanalysis. These values are also at
or above the climate maxes for this time of year per SPC upper air
climatology and the GEFS ensemble situational awareness table. With
deep saturation up to 300 mb per HRRR BUFKIT, this airmass will
favor very efficient rain-producer. So far since last night, rainfall
amounts have been almost exclusively under 0.60" given the fast
northeast movement of the showers (northeast at 35 mph). Weak
upper level support and a cold front will bring additional
chances for showers and storms later today into early tonight.
Surface based CAPEs will become substantial per HRRR topping
4000 J/Kg. Given a lot of instability, high precipitable water
values but more meager 0-6 Km shear, storms are expected to
become marginally severe to possibly severe from about 1 pm EDT
through the afternoon with the arrival of the upper level
support and occurrence of daytime heating. It looks like the
greatest severe weather threat will be from damaging winds. Wet
bulb zero heights appears to be too high to favor a large hail
threat.

Much cooler and less humid air will spread over the region
behind a cool front tonight. Highs Sunday will only be around
70 to 75 with lows Sunday night dipping into the 40s near the
Michigan border. Very warm air will quickly return with highs
well into the 80s by Tuesday. Energy in the form of short waves
in the northern stream will bring chances for showers and storms
from Wednesday through the end of the week. Temperatures should
be near normal during this time.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1241 PM EDT Sat Jun 29 2024

Confidence is increasing that KSBN will be dry for the
afternoon, with thunderstorms developing southeast of there
this afternoon, eventually moving over KFWA.

Surface observations indicate a moisture rich atmosphere is in
place ahead of a cold front. Clouds are thinning over eastern IL
and western IN, likely setting the stage for additional
thunderstorms this afternoon. Convection allowing models have
been rather consistent with storms impacting KFWA in the 22z to
00z window.

Otherwise, at both sites, plenty of MVFR ceilings are noted
upstream. The duration is a little uncertain at KSBN but
ultimately hedged toward the existing forecast. Later tonight,
there is there a 50-60% chance of MVFR stratus developing.
Time-height cross sections confirm this. Medium confidence at
best on the exact timeline, however.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement from late tonight through late Sunday
     night for INZ103.
OH...None.
MI...Beach Hazards Statement from late tonight through late Sunday
     night for MIZ177-277.
MARINE...Small Craft Advisory from 1 AM Sunday to 5 AM EDT Monday for
     LMZ043-046.

&&

$$

DISCUSSION...Skipper
AVIATION...Brown