IWX issues Area Forecast Discussion (AFD) at Oct 21, 6:23 AM EDT
922
FXUS63 KIWX 211023
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
623 AM EDT Wed Oct 21 2026
.KEY MESSAGES...
- Dense fog is expected this morning, particularly along and
east of Interstate 69. More patchy fog is possible tonight
with the greatest chances across northeast Indiana and
northwest Ohio. Some locally dense fog is possible again early
Thursday morning.
- Dry weather will continue through the weekend with
temperatures slightly above normal. Temperatures are expected
to cool to slightly below normal by next Tuesday and
Wednesday.
&&
.DISCUSSION...
Issued at 320 AM EDT Wed Oct 21 2026
Satellite imagery early this morning depicts an expansive area of
stratus/fog across northwest Ohio, with widespread dense fog
developing across south central Lower Michigan and northwest Ohio.
Weak easterly flow associated with eastern portions of low level
anticyclone will support westward migration of this stratus/fog into
far northeast Indiana over the next several hours. A Dense Fog
Advisory has issued earlier this morning for Hillsdale Co MI and all
of NW Ohio counties, and based on current trends, a westward
expansion will likely be required. With expansive low level
anticyclone in place and very weak low level flow, diurnal
mixing will likely be slow to erode stratus/fog, with areas of
fog persisting through the 14 to 15Z timeframe.
Otherwise for today will be monitoring the progress of a progressive
mid/upper level short wave trough across the Upper Midwest this
morning as it reaches the western Great Lakes region. A narrow
axis of mid level moisture/patchy mid level clouds will likely
remain north of the local area while another area of mid clouds
associated with mid level short wave progressing through mean
upper ridging will largely remain displaced to the west from the
Central Plains to the Mid MS Valley. A persistence forecast
largely utilized for high temperature forecast today as little
thermal advections have been noted over past 24 hours with
similar poor mixing profiles today and similar good amounts of
insolation.
Passage of the Great Lakes short wave this evening will allow for
reinforcement and southwestward shift to low level anticyclone
across the region. This should yield a weak northeasterly low level
flow profile for tonight which once again raises the question of
some enhancement to fog development downwind of eastern Great Lakes.
Given northeast trajectories, greatest confidence in fog development
tonight is far NE IN/NW OH mainly along and south of US Route 24,
but some patchy fog will be possible once again for many areas east
of I-69. THe fog may become locally dense once again early Thursday
morning.
A stable wave pattern will maintain through the first part of the
weekend with an eventual shift of longwave upper ridge axis
east of the local area by 2nd half of the weekend. This should
allow for Sunday to realize the warmest temperatures of the
period in the low to mid 70s. Longwave predictability begins to
break down early next week with large discrepancies in how
phasing is depicted with western CONUS closed upper height
perturbations among various deterministic/ensemble guidance.
Some indications that stronger frontal forcing will develop
northwest of the local area late weekend/early next week as
southwest CONUS upper wave pushes east and dampens, but given
uncertainty in progression and depth of this wave as it reaches
central CONUS argues for maintenance of mainly dry forecast at
this time with expectation that frontal forcing will wane
through time. Blended guidance idea of trend back to cooler
conditions early to mid next week still appears reasonable.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 620 AM EDT Wed Oct 21 2026
The combination of satellite/sfc obs/web cams across northeast
Indiana indicate a westward drifting area of dense fog across
northeast Indiana. Cigs of 200 feet or less and vsbys down to
1/4SM have approached the KFWA vicinity as of 10Z, and expecting
these conditions to hold through 14Z before improving. IFR/vsbys
will likely hold through mid morning before improvement back to
VFR conditions due to poor mixing in this synoptic setup. At
KSBN, fog is expected to be more patchy in nature, but cannot
rule out a period of brief IFR vsbys in fog early this morning.
An upper level short wave trough will track across the Great
Lakes region today allowing for a reinforcement and southwest
expansion of a low level anticyclone across the Mid MS River
Valley. This will keep a weak gradient in place through this
forecast valid period. With weak low level northeasterlies given
the re-orientation of the anticyclone today, flow trajectories
will be supportive of some more stratus and fog developing
across eastern Great Lakes tonight and building west again. Best
chances of more widespread coverage may be just south of KFWA
however.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Dense Fog Advisory until 10 AM EDT this morning for INZ006>009-
017-018-026-027-034.
OH...Dense Fog Advisory until 10 AM EDT this morning for OHZ001-002-
004-005-015-016-024-025.
MI...Dense Fog Advisory until 10 AM EDT this morning for MIZ079>081.
MARINE...None.
&&
$$
DISCUSSION...Marsili
AVIATION...Marsili
Source: IWX issues Area Forecast Discussion (AFD) at Oct 21, 6:23 AM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202610211023-KIWX-FXUS63-AFDIWX)
---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!