Area Forecast Discussion
Issued by NWS Grand Forks, ND
Issued by NWS Grand Forks, ND
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670 FXUS63 KFGF 301445 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 945 AM CDT Tue Apr 30 2024 .KEY MESSAGES... - Rain chances continue through the week with near normal temperatures. && .UPDATE... Issued at 944 AM CDT Tue Apr 30 2024 Fog will continue to diminish over the next several hours this morning. Fog will be gone by noon at the latest. Showers and thunderstorms are still expected later this afternoon and evening. UPDATE Issued at 610 AM CDT Tue Apr 30 2024 Fog has persisted long enough to become a nuisance but any pockets less than 1 mi have tended to be transient and last no longer than 1 hours any given area thus the hesitation to go dense fog advisory or even SPS. This should clear up as winds go from calm to gentle this morning helping to mix things up a bit. Anyways could see locally dense for in areas though 9am. && .DISCUSSION... Issued at 239 AM CDT Tue Apr 30 2024 The upper low currently centered over Thunder Bay Ontario will continue to drift east/northeast amid zonal flow. Shortwave ridging over western North Dakota will quickly pass over us today before the next trough ejects east out of western MT, arriving later today. In the meantime pockets of low stratus with drizzle may drop visibility as low as 1-3 miles with fog development possible under any of these areas of lower clouds. Only a 20-30% chance of fog development so leaving as just patchy fog for now and any areas that do see fog are unlikely to see dense fog (<1/4 mi) as the inversion is pretty weak. Might see some brief bouts of sun this morning and early afternoon though would bet on more clouds than not with the MT wave quickly approaching and associated clouds nearing by midday. Despite strong warm air advection from 850-700mb we will remain north of the effective surface warm front which will set up from the ND/SD/MN border east into north central WI keeping us on the cooler side today with highs in the 50s to low 60s in the far south. Rain begins by noon in eastern ND pivoting northeast overspreading the remainder of the FA by the evening commute. Could see a few thunderstorms in the far south epically in west central MN this afternoon and evening where steep mid level lapse rates >7.5 C/km and MUCAPE of 200-500 J/Kg could support some small hail though this is likely conditional upon the northward placement of the warm front and and afternoon heating at the surface during breaks in clouds which as mentioned before is expected to be limited. Overall looking for another widespread quarter to half inch but isolated higher totals remain possible in thunderstorms. This wave continues east Tuesday night with another day in the low 60s Wednesday. The parade of waves continues Wednesday night and beyond. Went ahead and grouped the late Wednesday night through Friday period as the next round, although it won`t continuously rain this entire time. There should be at least two areas of precipitation late Wednesday night into Thursday morning. During this period, a 700mb low remains pretty stationary over northeast Montana, while a wave rotates around its eastern side. The main area of precipitation should be down around southeast South Dakota into southern Minnesota, closer to the actual surface low. This convection should become elevated Wednesday night into Thursday morning, with good 850mb warm advection, a low level jet, and deeper moisture. Showers associated with this area may reach as far north as our southeast FA. A secondary area of precipitation also looks to develop over central or eastern North Dakota, associated with the upper jet and some 700mb frontogenesis. At this point, the NBM shows the highest probabilities for greater than 0.25 inches (50 percent) just brushing our far southeast FA to around 40 percent over central and eastern North Dakota. This system maintains pretty strong dynamics for Thursday afternoon through Friday, as the 700mb low consolidates over eastern North Dakota and lifts north-northeast. There should be somewhat of a break Friday night, before another little wave on Saturday skirts the far southern FA again. At this point, the deeper moisture continues to stay south of this area again, and the far southern FA would only be brushed with minimal rainfall. Brief ridging follows through at least Sunday, maybe even into early Monday, which would allow temperatures to get back to normal or even above normal (low 70s in the southern Valley). After this point, as the previous shift noted, one cluster shows a trough at the same time another cluster shows a ridge over the Plains. So although the forecast carries low chances for precipitation, the confidence is very low. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 610 AM CDT Tue Apr 30 2024 MVFR to IFR ceilings will continue through the day with locally dense fog to 1/4sm periodically dropping things to LIFR. this should end by 14z with persisting vis reductions below 3 miles until 15z. While ceilings may lift above IFR this morning as clouds attempt to clear there is minimal confidence in cloud trends and thus could remain IFR until rain moves in this afternoon. Unlikely to see widespread thunderstorms in the region today but FAR could get some VCTS from 21-01Z depending on convective trends. overall mostly just messy ceilings and nuisance rain but any lightning could throw a wrench in the forecast. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Perroux DISCUSSION...Godon/TT AVIATION...TT