053 FXUS63 KIWX 180514 AFDIWXArea Forecast Discussion National Weather Service Northern Indiana 114 AM EDT Thu Sep 18 2025
.KEY MESSAGES...
- Remaining warm and dry through Saturday.
- Rain shower chances (20-40%) arrive Sunday into early next week.
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.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.
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.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 110 AM EDT Thu Sep 18 2025
Broad anti-cyclonic flow (albeit weak) remains over the Great Lakes and with it the risk of some marine-modified air spilling over KFWA resulting in some fog. Guidance continues to hint at the possibility, but its magnitude and agreement among models is not as strong as 24 hours ago. Observations immediately downwind of Erie are starting to degrade. Trends will be monitored but now, am carrying on with the inherited TAFs. No fog concern at KSBN. Light wind again this afternoon with plenty of sun.
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.IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None.
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DISCUSSION...Steinwedel AVIATION...Brown
NWS IWX Office Area Forecast Discussion