563 FXUS63 KIWX 160738 AFDIWXArea Forecast Discussion National Weather Service Northern Indiana 338 AM EDT Tue Sep 16 2025
.KEY MESSAGES...
- Dry and very warm through Friday with highs in the mid to upper 80s.
- Showers are possible (20% to 40%) Saturday through Monday. An isolated thunderstorm is also possible.
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.DISCUSSION... Issued at 232 AM EDT Tue Sep 16 2025
At the onset of the forecast, ground conditions were becoming very dry over northern Indiana. Drought feedback was already apparent and was contributing to very large (and spectacular) diurnal temperature swings near 40 degrees (nearly 15 degrees above normal). This pattern will continue through Thursday.
A very large positive height anomaly remained over the Upper Great Lakes region to the southern portion of Hudson Bay near James Bay. 500 mb anomalies of around +400 meters were over this area and were supported by upstream teleconnections over western North America and the eastern Pacific. This upper level ridge will break down early this weekend as an abundance of energy undercuts the ridge. As a result, showers and perhaps an isolated thunderstorm are possible starting Saturday.
The latest array and WPC forecast keep overall precipitation relatively light through Monday and insufficient to improve drought conditions.
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.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 110 AM EDT Tue Sep 16 2025
Added FEW250 to the TAFs this morning in response to passing high clouds, per satellite. Marine-modified air may permit 5SM BR toward sunrise at KFWA. For now, upstream obs are VFR. Light wind again this afternoon with some fair weather cumulus thanks to continued high pressure.
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.IWX WATCHES/WARNINGS/ADVISORIES... IN...None. OH...None. MI...None. MARINE...None.
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DISCUSSION...Skipper AVIATION...Brown
NWS IWX Office Area Forecast Discussion