637
FXUS63 KIWX 040613
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
213 AM EDT Wed Jun 4 2025

.KEY MESSAGES...

- A Marginal Risk for severe thunderstorms and excessive
  rainfall will exist today. Strong wind gusts and localized
  nuisance flooding will be the main threats.

- Unsettled pattern will continue into next week with near
  average temperatures and additional chances for showers and
  thunderstorms.

&&

.DISCUSSION...
Issued at 205 AM EDT Wed Jun 4 2025

At the start of the forecast period, our area is compressed
between ridging to our east and a weak trough with attendant
cold front moving in to the area from our west. For at least the
first part of the day today, the persistent southwesterly flow
regime will keep Canadian wildfire smoke aloft over our area,
producing hazy skies. As the front moves through, high-
resolution smoke models suggest a generalized dispersion of the
smoke, at least temporarily.

The aforementioned cold front will move through the area today.
Climatologically significant moisture (HREF suggesting PWATs
near or just above daily running maximum PWAT for Lincoln, IL).
This coupled with a slowing boundary and storms likely to
propagate parallel to the front, suggests at least some threat
for heavy rain from training thunderstorms. In general, expect
widespread totals of 0.5 - 1.0 inches from this system. Steep
low-level lapse rates from a dry sub-cloud layer, especially
well out ahead of the front, along with CAPE on the order of
700-1000 and 30-35kt of 0-6km bulk shear, will allow for a few
strong to perhaps severe wind gusts - especially with any more
robust updrafts that can form ahead of the bulk of
precipitation. SPC and WPC maintain us in Marginal Risks for
Severe Storms and Flooding, respectively.

The wet/active weather will continue during this first week or
so of June, with few periods of clear-cut dry conditions. This
is supported by computer models favoring a large closed upper-
level moving low over the Great Lakes to start next week. This
will promote unsettled weather and keep temperatures at or below
average for this time of year.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 147 AM EDT Wed Jun 4 2025

Earlier showers and thunderstorms across northern Illinois have
dissipated to mainly showers, with the bulk of any remaining
thunder limited to portions of central Illinois. An impressive
prefrontal moisture axis will continue to shift eastward into
the area today. Large scale frontal forcing and possible aid
from outflows should help to form showers and embedded storms
across northern Indiana through the day, particularly across
northwest into portions of north central Indiana. Timing of this
threat at KFWA should be delayed more until the late afternoon
hours. Thunder is certainly possible, given magnitude of low
level moisture, but confidence in timing and extent of thunder
is a bit low for inclusion at this forecast distance and will be
reassessed with the 12Z TAFs. If thunder is able to develop,
cannot rule out some gusty winds with the stronger
showers/storms this afternoon. Will continue to include
prevailing showers into tonight as another upstream mid level
trough aides in rain shower coverage. As the sfc front sags
southeast into the area today, some MVFR cigs of 1-2k feet are
expected at KSBN, with a much later arrival time at KFWA.

Gusty winds to 25 knots are possible today, mainly at KFWA
through early afternoon. Low level winds should diminish in
magnitude later this afternoon. Did also include LLWS mention to
begin the 06Z TAF valid period with indications in VAD wind
profiles of 40-45 knot flow in low levels.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 8 AM EDT this morning for LMZ043-
     046.

&&

$$

DISCUSSION...Norman
AVIATION...Marsili