Sunrise 6:02 AM   Sunset 8:44 PM Moonrise 3:45 AM   Moonset 4:48 PM

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FXUS63 KFGF 051049 AFDFGF

Area Forecast Discussion National Weather Service Grand Forks ND 549 AM CDT Sun May 5 2024

KEY MESSAGES

- Organized thunderstorms are likely Monday through Tuesday, with a conditional threat of strong to severe thunderstorms south of I-94 Monday afternoon/evening.

UPDATE
Issued at 547 AM CDT Sun May 5 2024

Very patchy fog has developed. The worst visibilities that have been observed is 1/2SM, and it only lasted for a half hour. This will improve over the next 1-2 hours and should present little to no impacts.



DISCUSSION
Issued at 135 AM CDT Sun May 5 2024

06z surface analysis indicates a surface high over the Devils Lake Basin with an attendant surface ridge stretching down through Minnesota. This has created near calm winds at the surface. Dew point depressions across the area are between 2 and 6 degrees and there doesn't appear to be a whole lot of spatial patterns to it. For this reason, patchy fog is likely to develop in some spots overnight tonight, but the probability for widespread fog is very low. For today, dry conditions are expected with mostly clear skies. Afternoon cumulus clouds may form, but showers are very unlikely to develop today.

Attention then turns to a very strong extratropical cyclone that will develop over the central and northern plains Monday afternoon and evening. With strong synoptic scale forcing due to strong CVA, there is high confidence in a broad swath of convection. MUCAPE values in advance of this system range in the 250-750 J/kg range, so thunderstorms are likely to develop, especially along the surface theta-e front. With shear very good thanks to strong low-level and mid-level flow, a brief window of strong to severe storms may develop along a thin surface warm sector. Near surface backing in advance of the surface front will allow for a small area of enhanced streamwise vorticity (although this would end up being highly dependent on storm motion, which is very uncertain due to frontal orientation). This would create an environment conducive for low- topped supercells, which if it were to arise would bring the threat for damaging wind gusts (exceeding 58 mph) and tornadoes. A lot of this hinges on near surface destabilization, which will be very difficult without stronger differential temperature advection and diurnal heating.
Because of all of these uncertainties, the official SPC outlook keeps us out of severe potential. This will be something to monitor over the next day.

What is highly confident is widespread showers and thunderstorms will impact the region Monday and Tuesday. The bulk of the heavier rainfall rates will be tied to thunderstorms, primarily south of Highway 200. Rainfall amounts of at least 0.10" are expected, with the potential to cross 0.50" in some locations with thunderstorms. The chances for rain continue through the week before we see a pattern shift to drier conditions.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/
Issued at 547 AM CDT Sun May 5 2024

VFR conditions will prevail for the TAF period. Isolated MVFR to IFR visibility due to fog may impact any TAF site, but the duration should be an hour at most. This will improve after 13z to VFR for the remainder of the period. Winds today will eventually become southerly, peaking after 00z.

FGF WATCHES/WARNINGS/ADVISORIES
ND...None.
MN...None.

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