Tocsin, Indiana Weather Forecast Discussion

405
FXUS63 KIWX 172322
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
722 PM EDT Wed Sep 17 2025
.KEY MESSAGES...
- Remaining warm and dry through Saturday.
- Rain shower chances (20-40%) arrive Sunday into early next week.
&&
.DISCUSSION...
Issued at 221 PM EDT Wed Sep 17 2025
Stagnant warm and dry pattern will remain locked in through Friday
(and probably into Saturday) with upper level ridging and subsidence
the dominant feature over the region. A round of height falls through
southeast Canada likely forces a backdoor cool front into this
ridging later Thursday night into Friday, washing out near the
US 30 corridor. This should shave a few degrees off highs on Friday
in our northeast with lacking forcing and washed out nature suggesting
nothing more than some diurnal CU near the front.
Chances, albeit low (20-40%), for showers and isolated storms enter
the forecast Sunday into early next week as the blocking pattern
gradually weakens with broad longwave troughing shifting east toward
the MS River Valley. Leading southerly flow does advect better
moisture into the area in advance of the trough axis with several
embedded shortwaves to swing through the North-central US and
western Great Lakes. The first wave on Sunday appears weaker with
lingering dry/subsident air potentially limiting shower coverage.
Better shower and iso storm prospects arrive around
Monday/Tuesday as a more amplified shortwave and frontal boundary
ejects into the western Great Lakes, though daily PoPs remain on
the low side given differences in timing and amplitude. Temps
generally near to above normal otherwise.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 722 PM EDT Wed Sep 17 2025
Still within an area of mid level ridging between a low
pressure area across the Mid Atlantic and a high pressure area
across the Rockies and SW Canada and this allows VFR conditions
to continue their hold across most of this TAF period. The one
question will once again be on the potential for morning fog.
Cross over temps are just touched at FWA, but not met at SBN.
Forecast soundings look more like a shallow ground set up even
at FWA tonight whereas soundings do not look conducive at SBN.
Aviation guidance is still showing a couple hours of 2 miles
starting at 10z tonight. With this in mind, am inclined to leave
the FWA TAF the way it is with tempo MVFR VISBY, but wouldn`t
be surprised to see just shallow ground fog there tomorrow AM.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Steinwedel
AVIATION...Roller

NWS IWX Office Area Forecast Discussion