Area Forecast Discussion
Issued by NWS Grand Forks, ND
Issued by NWS Grand Forks, ND
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360 FXUS63 KFGF 131813 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 113 PM CDT Thu Jun 13 2024 .KEY MESSAGES... - Unsettled period heading into next week with 500 mb trough west and ridge east and area in southwest flow aloft. - There is a 15 percent probability of another round of severe thunderstorms on Monday. && .UPDATE... Issued at 113 PM CDT Thu Jun 13 2024 Scattered showers and thunderstorms are developing in northwest Minnesota as temperatures reach convective temperature (low to mid 70s). A recent report of very small hail smaller than the size of peas came in from Roseau as a small thunderstorm moved over around 1 PM, thus confirming today`s potential for small, non-severe criteria hail. There is still the low chance for isolated thunderstorm gusts to 50 mph in northwest Minnesota this afternoon, for the reasons explained in the previous update discussion. UPDATE Issued at 1009 AM CDT Thu Jun 13 2024 Overall, the forecast remains on track as previously discussed. Daytime heating will breezy winds aloft transfer to the surface, allowing for gusts in the 20-30 mph. Deep mixing of the boundary layer between 800-700 mb will allow the potential for relatively stronger thunderstorms within northwest Minnesota this afternoon to produce wind gusts up to 50 mph, in addition to the potential for small (pea sized) hail. Should storms tap into all available instability near 1000 J/kg, these gusts should be realized. Additionally, the coverage of such gusts will be quite small, with only perhaps one or two storms producing. Overall, the chance for severe wind gusts 60 mph or greater remains very low (less than 10%) given a lack of better instability and higher winds aloft displaced just to our south. UPDATE Issued at 642 AM CDT Thu Jun 13 2024 Skies clear over the fcst area as we approach 12z. Upper wave is north and northwest of area and approaching Brandon MB. It will move southeast and generate isold-scat t-storms midday and aftn in far NE ND and NW MN per forecast. && .DISCUSSION... Issued at 234 AM CDT Thu Jun 13 2024 ...Synopsis... For today, we will be dealing with a 500 mb low over the Manitoba lakes and a short wave which is well seen moving on the south side of the upper low near Yorkton SK. This wave will move east-southeast toward toward Lake of the Woods region. 500 mb temps in the -17/-18C range near the ND/MB border and into NW MN along with daytime heating into the 70-75 range will create MU CAPES in the 500-800 j/kg range, with 20 pct chance of MU CAPE in the 1000-1100 j/kg range near Roseau and Baudette. Bufkit sounding profile for BDE shows that steep lapse rate 7.5 C/km. All of this is sufficient for scattered thunderstorms to develop today Langdon to Thief River Falls to Bemidji area north. Pea size hail wouldn`t be out of the question from some storms, but expect non-severe. This follows Day 1 SPC outlook as well. Scattered storms diminish early this evening and tonight into most of Friday look dry with clear to partly cloudy sky as the colder air aloft move east. ...Unsettled period into next week... 500 mb ridging builds into the northern Plains Friday night but the building ridge quickly shifts east toward the Ohio Valley and Mid Atlantic region Sunday and holds there thru most of the next week. This will set the region up in a southwest flow aloft with periodic short waves moving northeast in the flow through the area giving chances for showers and thunderstorms. Position of front will be critical to where any severe threat lies with ECMWF remaining slower to advance 500 mb trough to our west east vs GFS. Per SPC discussion on days 4-5 severe threat will side more toward a slower ECMWF progression. That would leave south/east half of the fcst area in some strong/severe threat early next week, while significantly cooler air and more showery weather occurs west central/northwest into north central ND incl Devils Lake region. From Grand Ensemble in DESI the probs for more than 1.5 inch of rain Sun-Wed next week is highest in warm sector due to more convective nature of the rainfall...roughly over the southeast fcst area and southeast from there toward the Twin Cities and up toward Duluth. ...15 pct probability of severe weather next Monday... SPC in its Thu AM update kept a 15 pct prob of severe in the RRV and MN for Monday. Uncertainty on frontal location means no outlook for Tuesday. But there will be sufficient instability in the warm sector Monday with ECMWF maintaining a stormier outlook vs GFS which pushes warm unstable airmass far south and east. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 113 PM CDT Thu Jun 13 2024 Scattered showers and thunderstorms will persist in far northeast North Dakota into northwest Minnesota this afternoon. This may briefly impact sites like KTVF and KBJI between 19Z-00Z. Confidence is not high enough to include TS or VCTS at these sites, but if confidence increases enough, will amend to include. There is a small chance (10%) erratic wind gusts underneath thunderstorms will reach 30-45kt. Otherwise, VFR conditions are expected with scattered cumulus between 4-6kft between 18Z-01Z today. Winds turn light and variable after 04Z this evening into Friday morning. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...CJ/Riddle DISCUSSION...Riddle AVIATION...CJ