Area Forecast Discussion
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
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477 FXUS63 KBIS 010318 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1018 PM CDT Fri May 31 2024 .KEY MESSAGES... - Dry Saturday, then chances for showers and thunderstorms return later Saturday night through the first half of next week. Near or slightly above normals highs in the 70s and 80s through much of the work week. - Isolated to scattered severe storms will be possible over central North Dakota into the James River Valley Sunday afternoon and evening. && .UPDATE... Issued at 1014 PM CDT Fri May 31 2024 Radar shows an increase in activity north of Interstate 94 as a modest short wave rotates through cyclonic flow aloft, but KBIS sounding shows quite the dry layer down low. Thus, will keep chances limited to isolated/scattered showers which anticipate to mainly remain quite light if anything reaches the ground. UPDATE Issued at 702 PM CDT Fri May 31 2024 Showers and a few thunderstorms remain mainly over northern parts of the area. For early evening update, main change was to adjust precipitation chances a bit with current trends, as a few showers remain a bit further south than previously though. && .DISCUSSION... Issued at 250 PM CDT Fri May 31 2024 The dominate feature for the forecast period is a blocking upper level low that will establishing it and linger over the Canadian Prairies today through the middle of next week. A series of shortwaves tracking around or below this low through this period will promote periods of showers and thunderstorms over North Dakota when their influence enters the northern Plains. Today, a surface high pressure center lingers over northern South Dakota. Conditions remain primarily clear, though an incoming bundle of shortwave energy aloft will allow for showers and potentially an isolated thunderstorm or two to develop across portions of the northwest and north central this afternoon. There is some modest instability developing over portions of the southwest and south central by the mid afternoon, however model soundings reveal a distinct lack of sufficient moisture that is unfavorable for even isolated convection over this area. High temperatures today are forecast broadly from the mid 60s west and the lower 70s east, still somewhat cool for the season. Winds are out of the southwest from 10 to 15 mph, with some gusts up to 25 mph across the north, but are anticipated to generally diminish through the rest of afternoon and evening. Lows tonight are forecast broadly in the 40s across the forecast area, a little warmer compared to yesterday. Saturday is looking to be another pleasant day, with primarily dry and calm conditions expected across the forecast area. Sky cover will diminish through the afternoon, becoming mostly sunny through the afternoon and evening. Winds will turn to the west through the morning and remain fairly light, though breezy conditions with sustained speeds from 15 to 20 mph will be possible across the International Border as an upper level jet pushes across the southern Canadian Prairies. Highs on Saturday return to near or slightly above normal, in the 70s across all of North Dakota. Overnight lows are forecast in the 50s. Saturday night into early Sunday, the more energetic shortwave trough and associated surface low center will push into the forecast area from the south. With highs forecast in the 70s and 80s, rebounding low level moisture levels, and steep lapse mid-level lapse rates over much of the central North Dakota, the environment ahead of this system will be fairly buoyant. Current model MUCAPE across the south central by the early Sunday afternoon range in the 1000-2000 J/KG along with 30 - 35 knots of shear, increasing to 2000- 3000 J/KG and 35 to 40 knots of shear over the James River Valley by the mid afternoon. As such, widespread showers and thunderstorms are expected on Sunday, with window where strong to severe storms will possible over the south central. At it stands, the SPC have placed much of the James River Valley in a Slight (level 2 of 5) risk for severe thunderstorms on Sunday, with much of central North Dakota in a Marginal (level 1 of 5) risk as well. There still remain questions as to how long these stronger storms will be viable, by the late afternoon and early evening MUCAPE drops off considerably, and the potential for early convection may exhaust the atmosphere prematurely. For early next week, off and on chances for showers and thunderstorms will continue as more shortwaves travel along the stationary upper level low, with the highest chances for showers (50- 80%) and thunderstorms (20-40%) on Tuesday as another energetic pacific shortwave arrives into the northern Plains. By Wednesday, longwave ridging pushing over the rockies will displace the block low and eastward and promote drier conditions through the remainder of the week. Highs through the first half next week remain at or above seasonal normals, broadly in 70s and 80s, before returning to the upper 60s and 70s by the end of the workweek. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 702 PM CDT Fri May 31 2024 Scattered showers and isolated thunderstorms remain over northern portions of the area this evening, possibly bringing very brief periods of MVFR/IFR visibility. The showers will decrease in coverage as the evening goes on. Otherwise, VFR conditions are expected. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...JJS DISCUSSION...Adam AVIATION...JJS