Area Forecast Discussion
Issued by NWS Grand Forks, ND
Issued by NWS Grand Forks, ND
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928 FXUS63 KFGF 181454 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 954 AM CDT Sat May 18 2024 .KEY MESSAGES... - Winds gusting to 45 mph are expected across much of eastern North Dakota late this morning through early evening. - An active pattern will keep occasional thunderstorm chances in the forecast through the middle of next week. Isolated strong to severe thunderstorms may be possible Sunday afternoon near far southeast North Dakota. && .UPDATE... Issued at 954 AM CDT Sat May 18 2024 Continuing to track showers east with no lightning activity yet but briefly gusty winds to 40 mph. Starting to see a better signal for some stronger storms with lightning activity by the time the line currently near Grand Forks makes it northeast to Lake of the Woods. UPDATE Issued at 704 AM CDT Sat May 18 2024 Line of showers (maybe an isolated thunderstorm) is approaching our western CWA along the leading edge of the main mid level circulation (still near the SK/ND border region). I made some adjustments to better reflecting the current timing (and lull) between periods of rain, otherwise forecast is on track. && .DISCUSSION... Issued at 347 AM CDT Sat May 18 2024 The large scale pattern will be influence by a mid/upper trough developing over the Intermountain West Sunday into early next week that eventually breaks down allowing zonal flow to reestablish itself over the Northern Plains by late next week. Actual flow/jet streams may behave more like "split-flow" around this trough and there is a higher variation in the position of southwest flow and evolution of waves ejecting through southwest flow or eventually the northerly flow as the trough moves east. This creates particularly large variations in how forcing/insatiability and ultimate QPF/thunderstorm chances evolve (including any related impacts). High temperatures will tend to vary from the 60s to lower 70s, though there is reasonably high spread related to the progressive nature of the surface pattern and any frontal zones/precipitation/clouds that may develop. Regarding winds: The current mid level wave exits to the east through the day with morning rain/embedded thunderstorm ending. Another period of showers may develop across our north with the cold pool/mid level vorticity across our north through the afternoon. This may be enough to result in more cloud cover that could limit mixing and higher end gust potential. Still, as unidirectional westerly flow increases even a shallower mixed layer should support gusts occasionally to 45 mph across much of eastern ND. This aligns with NBM probs for greater than 40 mph gusts (90% chance). Confidence at this point was high enough to issue a Wind Advisory for most of our ND counties (excluding far southeast ND). Regarding severe thunderstorm chances: Instability has greatly decreased this morning and cloud cover could limit daytime heating/low level lapse rates today. While there may be higher vorticity environments in our north closer to the mid level circulation, I wouldn`t anticipate funnel development unless we see more breaks in advertised mid level clouds during peak heating. On Sunday afternoon/evening there is some guidance that shows a window for isolated strong or severe thunderstorms (large hail a primary threat) in our far southwest as the next mid level shortwave rotates northeast within SW flow (variation in how that pattern evolves). BL Td`s increasing and steepening mid lapse rates are shown to contribute to elevated instability in the 1000-1500 J/KG range while effective shear could be anywhere from 30-50kt. Due to the high variation in surface pattern (frontal zone may not set up this far northeast) and stronger capping could limit the severe risk into our area. Worth monitoring though. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 704 AM CDT Sat May 18 2024 THere is a small pocket of MVFR ceilings progressing into northwest MN (resulting in brief impacts where it tracks) otherwise VFR should prevail (4-8 KFT AGL CU). Scattered showers (isolated thunderstorms) will progress over eastern ND and into northwest MN through midday before exiting to the northeast into Canada this afternoon. westerly winds should increase through midday with occasional gusts as high as 40kt in eastern ND, decreasing this evening with sunset/loss of daytime mixing. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Wind Advisory until 7 PM CDT this evening for NDZ006>008- 014>016-024-026>030-038-039-054. MN...None. && $$ UPDATE...TT DISCUSSION...DJR AVIATION...DJR