282 FXUS63 KFGF 180351 AFDFGFArea Forecast Discussion National Weather Service Grand Forks ND 1051 PM CDT Wed Sep 17 2025
.KEY MESSAGES...
- A wet period is setting up from tonight through Friday night, with the focus for the highest rainfall potential across southeast North Dakota and west central Minnesota. Outdoor activities and ongoing harvest will be impacted to varying degrees.
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.UPDATE... Issued at 1051 PM CDT Wed Sep 17 2025
Radar is starting to fill in across the south, with a hundredth of rain now reported at Elbow Lake. A hundredth is not much, but this is the very beginning of what will become a soggy few days for this FA. The expectation is for rain to really ramp up in areal coverage in our southern two tiers of counties over the next 3 hours or so.
UPDATE Issued at 637 PM CDT Wed Sep 17 2025
Dry air at the surface is keeping the handful of radar returns in our far south from reaching the ground. However, the atmospheric column will continue to saturate over the next several hours, with rain expected to begin in the far south around midnight. From there, it will slowly inch northward overnight, reaching about I94 by sunrise. Outside of short term adjustments to match this idea in the grids, the rest of the forecast remains on track.
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.DISCUSSION... Issued at 246 PM CDT Wed Sep 17 2025
...Synopsis...
A pair of upper lows to our west will wobble east and rotate around each other as we head into the later part of the work weak. The southernmost upper circulation will lift northeastwards towards the ND/SD border tomorrow, remaining over the Dakotas through Friday before moving off into the upper midwest over the weekend. Another upper low starts to move into the Dakotas for Monday, and then down into the central MS Valley by the middle of next week.
...Rain tonight into Friday night...
ECMWF EFI has a fairly robust wet signal for the Dakotas from tonight through 00Z Saturday, then again for Monday. Instability looks fairly weak, although some ensemble members bring some CAPE into our southern counties for tomorrow, with probability of over 1000 J/kg around 25 percent. With not a lot of CAPE and deep layer shear around 30 kts, the main issue continues to be heavy rainfall. Probabilities for over an inch of rain through Friday night are still highest in southeastern ND, ranging from 50 to 80 percent. Chances for heavy rainfall trail off significantly further northeast, with less than half an inch expected near Lake of the Woods. The rainfall is expected over several days and should not all come at once, with the 75th percentile for 6 hourly QPF not getting above half an inch. At this point, think rain should soak in pretty well and will not message much more than we already have.
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.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1051 PM CDT Wed Sep 17 2025
Conditions are expected to go down hill dramatically overnight into Thursday morning, with VFR giving way to MVFR, eventually turning to IFR at multiple sites. Even if IFR is not prevailed at a specific sites TAF, pockets of IFR will likely be roaming around throughout Thursday, leading to brief instances of lower ceilings. At this time, it remains too early to add a TEMPO or PROB30 to account for this outside of where IFR is expected to prevail. Showers will also be passing through. Visibilities will change very little in areas where it is raining vs areas where it is not, as a mix of drizzle/mist will likely persist in between the periods of rain. Ceilings will lower again Thursday night. How low they go is uncertain, but places where we see persistent IFR Thursday afternoon (such as KDVL) could see LIFR by Thursday night.
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.FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None.
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UPDATE...Rafferty DISCUSSION...JR AVIATION...Rafferty
NWS FGF Office Area Forecast Discussion