388 FXUS63 KFGF 200553 AFDFGFArea Forecast Discussion National Weather Service Grand Forks ND 1253 AM CDT Sat Sep 20 2025
.KEY MESSAGES...
- Scattered showers and isolated thunderstorms tonight, then shower chances slowly diminishing west to east over the weekend. Dry next week.
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.UPDATE... Issued at 1253 AM CDT Sat Sep 20 2025
Showers remaining confined to eastern North Dakota with fog developing mainly in areas coinciding with this deformation forced precip in far northeast North Dakota and more scattered instances in southeast North Dakota. not seeing any reason for truly widespread dense fog to form at this time but will continue to monitor.
UPDATE Issued at 1014 PM CDT Fri Sep 19 2025
Main areas of light rain showers/heavy drizzle are in eastern North Dakota with lower coverage to the east, and activity continue to generally follow expected trends. Main adjustment was to add mention of fog to the forecast for the nighttime period tonight/morning period Saturday.
UPDATE Issued at 646 PM CDT Fri Sep 19 2025
There are several smaller pockets of showers where coverage is a bit better (one near lingering deformation band in northeast ND), otherwise coverage has become much more scattered following trends from previous forecast updates. Light fog is expected to develop tonight, but impacts would be limited to aviation with most vis above 1sm. Minor adjustments were made to near term trends, otherwise the forecast remains on track.
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.DISCUSSION... Issued at 232 PM CDT Fri Sep 19 2025
Upper low centered over eastern SD will move slowly into southern MN tonight. Meanwhile, the weaker circulation along the southern Saskatchewan/Manitoba border will close off over eastern ND during the day tomorrow. CAMs show a trend of showers weakening overnight as the first upper system pulls east and then shower activity picking up again tomorrow as the northern upper system moves down, and this seems fairly reasonable. Some MU CAPE of 500-1000 J/kg in our far south could allow for some isolated cells getting tall enough for lightning, but with minimal shear any lightning threat will be short lived and sporadic this evening. HREF has 70 percent probabilities of over an inch of rain in the southern Red River Valley through tonight and tomorrow. Probabilities of over 2 inches however, are less than 20 percent. Some spots could see some moderate rainfall rates moving over, but not enough to cause impacts other than the usual delays in outdoor activity due to rain.
The upper trough pulls east into MN/WI on Sunday, and showers will taper off by the end of the weekend. The upper trough continues out over the Great Lakes on Monday, and there will be a continued drying trend into the upcoming week. There is decent agreement with the ensemble members on a fairly blocky ridge setting up over the Rockies and troughing staying south over the OH Valley and Midwestern states. Conditions again turn towards drier and warmer than average for our part of the Northern Plains. Average temperatures are trending down however, and readings will not be as hot as previous warm spells.
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.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1130 PM CDT Fri Sep 19 2025
Low level moisture continues to remain in place as the slow moving upper low persists, with scattered showers slowly decreasing in coverage (better coverage lingering in northeast ND early in the TAF period). Outside of a few localized "holes" within the IFR stratus resulting in short periods of improvement, IFR ceilings are expected to prevail through the Saturday morning hours with a period of LIFR ceilings and potential light fog development (1-3sm) after 06Z through 14Z. Eventually ceilings and visibility begin to improve Saturday afternoon/early evening, however this is the type of pattern that guidance often overestimates the duration/coverage of improving ceilings and I wouldn`t be surprised to see MVFR continue to prevail at most sites. The best chance for VFR ceilings would be towards central ND (possibly KDVL).
Winds remain light and variable as weak surface gradient and low pressure slowly shifts east through the TAF period (eventually prevailing from the northwest).
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.FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None.
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UPDATE...TT/DJR DISCUSSION...JR AVIATION...DJR
NWS FGF Office Area Forecast Discussion