835 FXUS63 KGRR 141742 AFDGRRArea Forecast Discussion National Weather Service Grand Rapids MI 142 PM EDT Sun Sep 14 2025
.KEY MESSAGES...
- Dry weather most of this week
- Chance of showers and thunderstorms starting Friday
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.DISCUSSION... Issued at 304 AM EDT Sun Sep 14 2025
- Dry weather most of this week
Flow over the eastern CONUS will resemble a Rex block pattern (ridging with the polar jet and troughing with the subtropical jet) beginning early this work week. Being a blocky pattern, it should persist for several days. And, given rather sharp ridging aloft in our vicinity, we can expect dry and abnormally warm maximum temperatures. We are now looking at upper 80s Wednesday/Thursday, and this could easily be exceeded on Thursday especially.
- Chance of showers and thunderstorms starting Friday
Model guidance has been fairly consistent with bringing an upper shortwave trough to the western Great Lakes, which will bring more seasonal temperatures along with a chance for showers and thunderstorms. Predictability is limited given weak and poorly phased flow aloft, especially regarding precipitation chances. QPF is broad-brushed areally and temporally (across multiple days including the weekend) to illustrate the uncertainty. But in reality, precipitation may be quite episodic and spotty with any accumulations not expected to make much of a dent in our recent precipitation deficits.
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.AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 142 PM EDT Sun Sep 14 2025
Little to no aviation concerns are expected the next 24 hours. Skies are expected to be mainly clear outside of some FEW-SCT cumulus development out of the east this afternoon and early evening. Overnight we are expecting some fog and stratus to form with a push of moisture off of Lake Huron in easterly flow. The bulk if not all of the fog should be north of the TAF sites across Central Lower Michigan. We did bring 4 miles and fog into the LAN TAF in the 10z to 14z time frame as that airport will be closest to the fog bank. The fog will burn off rather quickly Monday morning. Bottom line, mainly VFR weather expected across the TAF sites through 18z Monday. Winds will be light easterly the next 24 hours.
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.MARINE... Issued at 304 AM EDT Sun Sep 14 2025
Winds and waves are expected to remain below hazardous levels. As noted previously, the larger scale flow will generally be light and offshore. However, large diurnal temperature swings are expected over Lower Michigan and this will promote an active lake/land breeze diurnal cycle.
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.GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None.
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DISCUSSION...TJT AVIATION...Duke MARINE...TJT
NWS GRR Office Area Forecast Discussion