474
FXUS63 KIWX 031818
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
218 PM EDT Thu Jul 3 2025

.KEY MESSAGES...

- A stray shower or storm possible (10-20%) into early this evening,
  and then again Friday afternoon into early Friday evening.

- Hot and humid Friday through this weekend.

- Better chances (30-50%) for scattered showers and storms
  arrive Sunday afternoon into Sunday night.

&&

.DISCUSSION...
Issued at 217 PM EDT Thu Jul 3 2025

Convection should be very limited again late this afternoon into
early this evening in the vicinity of a lake shadow/breeze given
limited boundary layer moisture and warm/dry mid-levels. Attention
later tonight into Friday morning will turn to how upstream
convection across WI evolves on the leading edge of a building ~592
dam 500 mb ridge. This activity should struggle to survive east-
southeast as it outpaces its LLJ and associated moisture
transport/convergence. Whether a MCV, cloud debris, or a more robust
outflow boundary folds into portions of our area on Friday
remains uncertain and could hold temperatures down a bit with
non-zero shower/storm chances. At this point, this kind of
impact locally appears less likely (only a 10-20% PoP) with the
upper ridge rather aggressive to build in with dry conditions
and highs making a run at 90F likely for most locations.

Upper ridge axis will be overhead on Saturday with hot and dry
conditions prevailing. This ridge breaks down into Sunday as a
dampening shortwave tracks east into the Great Lakes and forces a
slow moving cold front through Sunday afternoon-night. Pronounced
moisture pooling per ~2" precipitable water values, and moderate
boundary layer destabilization pre-frontal Sunday afternoon, while
overall flow/shear through the column is weak given the shearing
nature to the wave. Similar to previous events, threats appear to
locally heavy rainfall and gusty winds (wet downbursts) with
scattered thunderstorms during this time.

Ensembles continue to support broad upper level troughing across the
Midwest and Great Lakes next week with seasonable temps. Mainly dry
conditions should also win out in this regime, though did retain NBM
low PoPs given the non-zero potential for mainly diurnally driven
showers/storms with any weak embedded mid level impulses, and along
any outflow/lake boundaries.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 128 PM EDT Thu Jul 3 2025

A weak shortwave approaches from the northwest during the afternoon
and evening hours tonight and may be able to set off an few isolated
showers or thunderstorms before the day is done. One fly in the
ointment is that an outflow boundary from yesterday`s storms
appeared to settled south of US-30 and that may completely remove
today`s chance for a shower or storm. As such, will lean entirely
dry for this forecast. As a result, aside from some patchy morning
ground fog, expect VFR conditions throughout. Wind-wise, our
northwest winds veer overnight to become more southwesterly on
Friday with a warm front now north and east of the area.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Air Quality Alert from midnight tonight to midnight EDT Friday
     night for INZ020.
OH...None.
MI...Air Quality Alert from midnight tonight to midnight EDT Friday
     night for MIZ177-277.
MARINE...None.

&&

$$

DISCUSSION...Steinwedel
AVIATION...Roller