Area Forecast Discussion
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
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022 FXUS63 KBIS 101806 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 106 PM CDT Mon Jun 10 2024 .KEY MESSAGES... - Showers and thunderstorms will gradually expand eastward through the day today before ending from west to east this evening through tonight. Isolated to scattered severe thunderstorms are possible across western and south central North Dakota, with the highest risk in the southwest. This risk is a level 1 out of 5 risk, except for Bowman and Adams counties, which are a level 2 out of 5 risk. - Near average temperatures expected today and Tuesday. Highs on Wednesday will be warmer, in the 80s, possibly reaching 90 in the southern James River Valley of North Dakota. - Chance for showers and thunderstorms (30 percent) return Wednesday evening, before higher chances for precipitation at the end of the week and through the weekend. && .UPDATE... Issued at 106 PM CDT Mon Jun 10 2024 Widespread showers are present across most of western and north central ND at this time. With a loss of instability, lightning has been gradually decreasing, though an occasional rumble of thunder remains possible. These showers and thunderstorms will continue progressing east northeast today as the next line develops in or approaches from the west. This second line is where strong to severe thunderstorms are possible. One of the main limitations is instability. Thick cloud cover persists over most of western through central ND, including the James River Valley. There was a clearing developing in the far southwest, although this is filling in now. All in all, a few strong to severe thunderstorms remain possible, although it seems the best chances are in the far southwest. UPDATE Issued at 858 AM CDT Mon Jun 10 2024 A boomerang shaped line of showers, with thunderstorms on the backside, is present on an axis from approximately Williston to Hazen to New Salem. These showers and thunderstorms will continue pushing east northeast through the morning hours. Based on any instability persisting more to the south and west of the line, expect any thunderstorms to remain on the backside, though lightning activity may diminish as the line heads north and east into a more stable environment. The next wave of showers and thunderstorms is then expected to move from west to east through the area early this afternoon. Adjusted PoPs based on the latest radar trends. UPDATE Issued at 646 AM CDT Mon Jun 10 2024 A large area of showers and thunderstorms are ongoing from Watford City, to Elgin, and back to Dickinson and just north of Beach as of 1130 UTC, with some isolated showers developing east of this area. The NDAWN station south of Beach reported about half an inch of rain in one hour, so even these smaller thunderstorms are producing modest rain amounts. This will be something to watch later today if we get stronger storms and either training or multiple rounds of rain in a short amount of time. SPC mesoanalysis page shows a swath of 850mb warm air advection across most of western North Dakota in line with the current convection, with a low-level jet analyzed over this same region. We expect this to continue pushing northeast through the morning, with a break in precipitation before the surface low and attendant cold front currently analyzed in central Montana move closer. CAMs are still in relatively good agreement on showers and storms continuing to develop in the warm air advection regime, in addition to along and potentially behind the front as it moves through. Updated POPs a bit in line with current trends otherwise going forecast looks good for now. && .DISCUSSION... Issued at 359 AM CDT Mon Jun 10 2024 This morning, a shallow ridge aloft was moving into western North Dakota, while a shortwave trough was in place over the Northern Rockies, moving east. A surface low associated with the trough was beginning to deepen in northwest Montana, with low- level warm air advection spreading across eastern Montana and western North Dakota ahead of the approaching system. Scattered thunderstorms were ongoing in eastern Montana and southwest North Dakota as a low- level jet strengthened, but in an environment of very little bouyancy and weak bulk shear. Additional showers were visible on radar across the rest of Montana and into Wyoming. Southeast surface winds were beginning to strengthen in response to the low deepening. The expectation for today is for showers and thunderstorms to become more widespread as the surface low deepens and approaches from the west. High-res guidance is painting a relatively consistent picture in convection spreading northeast, initially along the warm air advection before additional development along a cold front as it pushes east through the afternoon and evening, following the trough axis. This afternoon into the early evening is the most likely time we would see strong to severe thunderstorms develop, when instability is maximized, as that is the primary limiting factor. The 00Z HREF did back off a bit on forecast MUCAPE, keeping values maxed out around 1000 J/kg in southwest North Dakota. Bulk shear still looks quite sufficient for severe thunderstorms, in the 40 to 50 knot range, while mid- level lapse rates are marginal. The tornado potential is low but non-zero, as forecast soundings continue to show high SRH, although this would be for a narrow window of time this afternoon in western North Dakota. Otherwise, main hazards are large hail up to the size of ping pong balls and damaging wind gusts up to 60 m. Uncertainty also comes from how earlier showers and thunderstorms, as well as widespread cloud cover, will impact the environment later in the day and potentially put a ceiling on storm strength. Some CAMs are advertising isolated storms developing in western North Dakota after the front moves through this evening, so something to keep an eye on. Heavy rain is also a possibility, with forecast PWATs on the upper end of climatology, especially if some locations get multiple rounds of heavy precipitation in a short amount of time. Northwest North Dakota has a high probability of at least 0.50" through tonight, with a 20-40% chance of at least 1" of rain. Precipitation chances taper off late tonight in our eastern counties as upper ridging begins to build into the western Canadian Prairies, starting a modest warming trend for the Dakotas. Tuesday should be a pleasant June day with highs in the mid 70s to lower 80s and mostly sunny skies, with a bit of a breeze east behind the exiting system. We warm up further still on Wednesday as a low-level thermal ridge extends into the region, bringing forecast highs to the 80s, with potentially some upper 80s in the James River Valley. Our next shortwave also comes through on Wednesday, and the timing of the wave and attendant cold front could impact how warm temperatures get if it moves through faster than expected. Right now, the timing of the front/wave keeps shower and thunderstorm development just east of the forecast area, but if this slows up, the James River Valley could have potential for some stronger thunderstorms. Dry and seasonable on Thursday before a more active pattern is projected to set up this weekend, as a closed low deepens over the Four Corners region before moving northeast through the central CONUS. Blended POPs increase across the area Friday afternoon and evening, continuing through the weekend and into Monday. Southerly return flow Friday and Saturday is hinting at increasing instability, so another window to watch for some potentially stronger storms. Temperatures through the weekend look to be near to slightly above normal for mid June. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 106 PM CDT Mon Jun 10 2024 Widespread showers are occurring in much of western and north central ND. These will continue moving/expanding eastward through the day. Presently, most of the instability has been lost and therefore lightning strikes are now few and far in between. However, anywhere showers are present, there is a greater than 25 percent chance of seeing lighting within the next hour. Therefore, vicinity thunderstorms with occasional thunderstorms are mentioned at most terminals. Another line of showers and thunderstorms is expected to develop west of any ongoing showers this afternoon. These storms have the potential to become strong to severe this afternoon through the early evening. While VFR ceilings and visibility are generally expected to prevail most of the time, conditions will deteriorate during any showers and thunderstorms. This includes lowered ceilings, reduced visibility, and erratic winds. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Telken DISCUSSION...Jones AVIATION...Telken