FXUS63 KFGF 190431 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 1131 PM CDT Mon May 18 2026 .KEY MESSAGES... - Another round of showers is expected this afternoon through tonight, bringing an additional few hundredths to two tenths of an inch across mainly southeastern North Dakota into western Minnesota. - Overnight temperatures could drop into the low to mid 30s west of the Red River Valley tonight, and a frost advisory is in effect. Temperatures drop again to near freezing across all of eastern North Dakota and western Minnesota Tuesday night. && .DISCUSSION... Issued at 230 PM CDT Mon May 18 2026 ...Synopsis... Large upper trough continues over the Rockies, with a lead shortwave starting to move through the southwest flow into SD. This shortwave is already bringing some light rain showers starting to move in around the Valley City area. The northern portion of the main upper trough will move into the Plains tonight and then off into Ontario tomorrow, with southern vorticity lobe still down near UT and NV. The northern shortwave moving through should help push high pressure down into the region Tuesday into Tuesday night. Winds return quickly back to the south on Wednesday under southwesterly flow aloft. The split trough remains over the western CONUS Thursday, but starts to move out into the Plains Friday into Saturday. A lot of variation in the ensemble members into how exactly the trough comes out and if there is another shortwave Sunday. Blended solution of some precipitation chances and temperatures rising above seasonal averages by Sunday and Monday continues to seem reasonable. ...Rain chances tonight... CAMs and global models in pretty good agreement on showers currently over the James River Valley spreading northeastward through the rest of the afternoon and into tonight. The bulk of the rain will be exiting out of our eastern counties between midnight and 6 AM, although there will be some lingering light showers/drizzle for a while after. All but portions of the Devils Lake Basin have high probability of seeing at least 0.01 of rain, and there is a 50 to 80 percent probability of at least 0.10 inches mainly in southeastern ND into western MN. ...Temperatures into the 30s tonight... Continued cold air advection pushes 850mb and even 925mb temps in some areas down below 0 C tonight. While skies will remain cloudy and there will be at least a little bit of mixing from northwesterly winds, temperatures look quite cold by tomorrow morning. NBM has probabilities 80 percent and higher for temperatures to get below 36 degrees, and even the less bullish HREF has 40 to 50 percent. With the clouds and wind do not think we will get down as low as the base NBM had us, so tweaked lows up a bit. We should stay above 32, but even with not much actual frost occurring the 33 to 36 degree range west of the Red River Valley could cause some issues to sensitive plants. Went ahead and matched neighbors for a frost advisory tonight. It does look to clear out and go light for winds tomorrow night, so better chances for freeze and frost look likely Wednesday morning. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1131 PM CDT Mon May 18 2026 Light to moderate rain is moving across eastern ND and northwest MN and will transition east of the region through 10Z. Vis within areas of rain is generally 3-6sm. IFR ceilings are expected to prevail across the region through at least 12Z, with improvement to MVFR by midday Tuesday and VFR by Tuesday evening (west to east). North to northwest winds 12-20kt are expected across much of the region, with periodic gusts around 25kt during the daytime period Tuesday. Winds should become light and variable with surface high pressure arriving Tuesday evening (along with clearing skies). && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Frost Advisory until 9 AM CDT Tuesday for NDZ006-007-014-015- 024-026-028-029-038-049-052-054. MN...None. && $$ DISCUSSION...JR AVIATION...DJR