Area Forecast Discussion
Issued by NWS Grand Forks, ND
Issued by NWS Grand Forks, ND
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362 FXUS63 KFGF 051808 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 108 PM 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. && .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 /18Z TAFS THROUGH 18Z MONDAY/... Issued at 103 PM CDT Sun May 5 2024 VFR conditions continue through the period. Winds forecast to become more southeasterly and increase after 00Z as a developing area of low pressure deepens and pushes across the area. Continuing to monitor conditions for tomorrow as the low develops with potential for low topped supercells late in the period. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ DISCUSSION... AVIATION...Hopkins