120 FXUS63 KIWX 061040 AFDIWXArea Forecast Discussion National Weather Service Northern Indiana 640 AM EDT Sat Sep 6 2025
.KEY MESSAGES...
- Mainly dry over the next 7 days. Only a 20% chance of showers or sprinkles north of US-6 tonight.
- Cool temperatures this weekend trend warmer, into the 80s, by the middle of next week.
- Dangerous swimming conditions expected for Lake Michigan beaches through Sunday.
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.DISCUSSION... Issued at 340 AM EDT Sat Sep 6 2025
Continued forcing of a ridge across the West Coast of the US via cyclonic wave breaks has allowed for a downstream trough across the Great Lakes region in concert with the normal negative Eastern Pacific Oscillation pattern. This pattern has allowed for cooler air across the area as an upper low has allowed cool northwest flow into the area. Within this trough over the Great Lakes, various shortwaves have traversed Lake MI providing various amounts of cloud cover and times of light rain. Given the reinforcing cold air and now finally some low level moisture to work with, a low chance for some lake enhanced light rain/sprinkles exists for tonight. The limiting factor would be the surface to low level dry air that could cause this all to dry up before it reaches the ground. The better low level moisture departs and the low level convergence weakens Sunday morning and so that`s when it`s expected that the lake enhanced cloud cover would begin to wane. High pressure is already into the area Sunday afternoon so expect a return to sunny skies then, which makes sense with the trough pushing into the West Coast of the US interrupting the EPO.
The aforementioned sprinkle chance is the only rain chance for the next several days, though, as plenty of dry air resides across the lower Great Lakes on the back side of a departing high pressure system even as weak mid level troughs swing through the area through the period. Given our location on the backside of the departing high pressure area during the first half of next week, weak warm advection allows a warming trend from Sunday into midweek next week from the cool 60s this weekend to reaching 80 degrees on Wednesday. There is a cold front that moves through during the latter part of next week, but that also appears to be a dry FROPA. High pressure is quick on its heels with dry weather continuing for next weekend.
There`s a potential to drop down into the upper 30s Sunday night, especially areas N of US-6 and E of I-69. This normally perks the ears up about frost potential, but at this time, it only looks like there`s an hour or two of such temperatures. With the potential for radiational cooling with high pressure overhead, this period may need to be followed.
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.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 640 AM EDT Sat Sep 6 2025
West winds continue through the period and we`ll have gusts starting around midday and continuing into the late afternoon as mixing into the low level jet commences. Low to mid level clouds wrap around the trough across the area, but CIGs should be high enough to maintain VFR conditions through the period. Showers will be possible within lake enhanced instability and a few may even traverse through SBN, but even if some do make it that far south, sfc-low level dry air should preclude lower flight conditions.
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.IWX WATCHES/WARNINGS/ADVISORIES... IN...Beach Hazards Statement until 11 AM CDT this morning for INZ103. OH...None. MI...Beach Hazards Statement through Sunday afternoon for MIZ177- 277. MARINE...Small Craft Advisory until 5 PM EDT Sunday for LMZ043-046.
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DISCUSSION...Roller AVIATION...Roller
NWS IWX Office Area Forecast Discussion