IWX issues Area Forecast Discussion (AFD) at Oct 22, 1:59 AM EDT
954
FXUS63 KIWX 220559
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
159 AM EDT Wed Oct 22 2025
.KEY MESSAGES...
- Lake enhanced rain showers persist through Thursday morning,
especially north of US 6.
- West/northwest winds could gust as high as 30 to 35 mph through
Wednesday.
- Below normal temperatures persist through the week ahead.
Highs Wednesday and Thursday struggle to get out of the low
50s.
- Widespread frost/freeze is likely Friday morning with
temperatures in the low to mid 30s.
- The active weather pattern and below normal temperatures
continue through the weekend and into early next week.
&&
.DISCUSSION...
Issued at 249 PM EDT Tue Oct 21 2025
A deepening low pressure system is currently centered over Lake
Superior. With a closed low aloft and good upper level support, this
system is expected to spin across the Upper Great Lakes region for
the next few days. The center of the low will gradually shift
southward over the eastern UP and northern Lower Michigan, providing
clouds, gusty winds, and periods of lake enhanced rain showers
across our CWA from this afternoon through midday Thursday. With a
tightening pressure gradient due to the deepening low,
west/northwest winds may gust as high as 30 to 35 mph at times later
today through Wednesday. Diurnally driven rain showers downwind of
Lake Michigan are expected to increase in coverage later this
afternoon and into the evening. At times, pockets of strong 500mb
vorticity pinwheeling around the center of the low will aid in lift
and potentially allow for a few thunderstorms to develop too. While
strong low level lapse rates of 8C/km or greater will work in
conjunction with cold air aloft to sustain these storms,
instability is lacking (only up to 250 J/kg SBCAPE across
southern Lower Michigan) so thunderstorm activity is expected
to be quite isolated. Today will be an active day but likely not
a hazardous weather day. If anything, small graupel and gusty
winds of 40 mph will be the main hazards. Tonight, the best
chances for continued lake enhanced showers will be north of US
6 where continued lift, CAA, and low level convergence will be
best.
Below normal temperatures last through much of the upcoming week.
The aforementioned midweek system and gusty winds will allow for
cooler temperatures to prevail across the Great Lakes region.
Wednesday and Thursday will be the coolest days of the week with
highs struggling to make it out of the low to mid 50s. The low
pressure system finally exits the Great Lakes region, which allows
for drier air to build in during the day on Thursday. The first
widespread frost/freeze of the fall season is likely Thursday night;
Lows will likely be in the low to mid 30s area-wide by daybreak
Friday and again on Saturday morning.
The active fall weather pattern looks to continue this weekend and
into early next week. A developing low pressure system across the
Mid Mississippi valley may yield some scattered low chances for rain
over the weekend, with better chances for rain arriving Monday and
Tuesday as yet another low pressure system traverses the central
Plains and into the Upper Midwest. Temperatures will continue to be
below normal into early next week.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 155 AM EDT Wed Oct 22 2025
MVFR cigs will remain likely this forecast valid period as a
strong low level thermal trough continues to remain anchored
across the southern Great Lakes into tonight. Cold air being
drawn across southern Great Lakes will allow lake
effect/enhanced rain showers to continue periodically at KSBN,
although best chances may be through daybreak. Given westerly
fetch considerations, KSBN may be located on southwest flank of
greater precip chances during the daytime hours, with the bulk
of rain showers expected to remain north of KFWA. The potential
of cigs below 2k feet still appears maximized at KSBN through
the early to mid afternoon hours today, with expectation that
diurnal mixing should promote cigs above 2k feet after this
time. Well mixed low levels and strong boundary layer winds
should support westerly gusts into the 25 to 30 knot range
today. Gusts should diminish somewhat after 00Z Wednesday
evening, but gusts to around 20 knots should continue into
Wednesday evening for both terminals.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Gale Warning until 8 PM EDT this evening for LMZ043-046.
&&
$$
DISCUSSION...Johnson
AVIATION...Marsili
Source: IWX issues Area Forecast Discussion (AFD) at Oct 22, 1:59 AM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202510220559-KIWX-FXUS63-AFDIWX)
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