959
FXUS63 KIWX 300742
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
342 AM EDT Mon Sep 30 2024

.KEY MESSAGES...

- Unseasonably warm temperatures through Sunday with highs daily
  around 68 to near 80. Cool nights with lows mainly in the
  40s.

- Fog likely east of I-69 early Tuesday; locally dense?

- Mainly dry except for a chance for non-severe storms east of
  I-69 Tuesday afternoon.

&&

.DISCUSSION...
Issued at 257 AM EDT Mon Sep 30 2024

The upper low that merged/absorbed Helene was still over Kentucky
early this morning and continued to gradually weaken. To the
north of this system, light showers were occurring over Ohio.
Some of these showers had spread into the Lima area overnight
where over a tenth of an inch of rain had fallen since 8 PM EDT.
Other very light rain/sprinkles were over northern Indiana,
apparently enhanced with the moisture flux from Lake Erie. Given
obs, trends, and the latest HRRR, this activity should continue
at times today and then end by early tonight as the upper level
system finally lifts out of the region to the northeast.

Challenges Tuesday include fog development early followed by
chances for thunderstorms during the afternoon. Very high dew
points for this time of year will persist over the forecast area
as the remnants of Helene/upper low move out of the region.
Some clearing is expected with light winds which should allow
fog to form before daybreak. Added areas of fog east of I-69
which appears to have the best chance for fog formation. Any fog
should mix out by mid morning ahead of an approaching upper
level system just coming out of the Rocky Mountains into Montana
and the Canadian Prairies. Expanded storm coverage slightly in
area and duration Tuesday afternoon. Storms should have
somewhat limited energy (CAPE generally up to 1000 J/Kg) and
limited low level wind shear up to the mid levels, so severe
storms are not expected. Otherwise, mainly dry weather is ahead
for the rest of the week. It appears cold air will remain north
of the area allowing highs to be generally above to much above
normal in the 70s.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 152 AM EDT Mon Sep 30 2024

Predominantly VFR to MVFR through the TAF period at both sites,
with IFR potential at KFWA. The upper level trough/low and
surface low (remnants of Helene) just to our southeast will
meander towards the Atlantic through the period. This will allow
an upper level ridge and surface high pressure to expand over
the entire forecast area by 6z tomorrow night. Because of this,
surface winds shift from NE to more easterly and become light
and variable just after sunset tonight. Mid level moisture
transport around Helene remnants is streaming across Lake Erie
as of this writing, with a band of stratus apparent on satellite
down the north-central part of the Lake and into Toledo, far SE
Lower MI, and NW OH/NE IN (down to Elkhart/Goshen and
Rochester). Expect ceilings around 1000 feet by morning at
KFWA,with some of the guidance dropping to 700 feet. Added a
tempo for now (10-14z). Otherwise expect predominantly MVFR
ceilings. Did keep a VCSH mention from 8z-17z for potential
drizzle that could materialize with the lake enhanced cloud
deck. KSBN may see some BR development if there are breaks in
the clouds for long enough tonight and winds can lighten up a
little bit, but confidence isn`t the greatest. Added a tempo
for 4SM and a return of MVFR ceilings 12-15z), however it
appears the lake band is creeping towards KSBN which may limit
how low vis gets. IFR conditions (possibly lower) are likely
just after the end of the period (6-12z Tue AM)-particularly at
KFWA which will see earlier and greater impacts. Have a tempo
for 5sm BR starting at 3z to account for this trend.

&&

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

&&

$$

DISCUSSION...Skipper
AVIATION...MCD