FXUS63 KBIS 190312 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1012 PM CDT Thu Jul 18 2024 .KEY MESSAGES... - High temperatures warm into the 80s today through the weekend. This is near to slightly above average for mid to late July. A few readings in the low 90s are expected in the southwest today. - Chances for showers and thunderstorms increase late this afternoon into the overnight, with a 20 to 50 percent chance of showers and thunderstorms Friday and then a 20 to 30 percent chance Saturday. - Severe weather chances are very low through this weekend, though a strong storm or two isn't out of the question on Friday. && .UPDATE... Issued at 1007 PM CDT Thu Jul 18 2024 A few weak showers are now lingering through central North Dakota, though this activity may be on the increase later tonight as the next wave rotates into the area. CAMs continue to show an increase in activity as the night goes on. UPDATE Issued at 655 PM CDT Thu Jul 18 2024 A few showers continue to loiter over west-central North Dakota around the Beulah-Stanton-Hazen area in area of higher instability as an upper level wave moves through. Expect a few more showers and thunderstorms through this evening. Otherwise, going forecast remains on track. UPDATE Issued at 500 PM CDT Thu Jul 18 2024 Have added some isolated showers and storms over parts of central and western North Dakota for late this afternoon into early evening as a few echos are starting to show up on radar. The showers that have shown up are in the Killdeer to Beulah area in the vicinity of a surface boundary while aloft a little wave is making its way through the region. Instability is available but shear is not the best, so do not expect these to get too frisky. Chances later this evening and overnight that were in the previous forecast continue. && .DISCUSSION... Issued at 235 PM CDT Thu Jul 18 2024 Today, a persistant upper level ridge lingers over to the west of the forecast area, with the associated thermal ridge progressing a little further eastward this afternoon. As such, at or above normal high temperatures are forecast, broadly in the 80s in the north and central while portions of the west are expected to see temperatures break into the lower 90s. A weak impulse of energy will traverse down the ridge and approach our west this afternoon and evening, promoting chances (10 to 20%) for showers and possibly even some thunderstorms later this afternoon and evening. While moisture returns are beginning to increase across the northern Plains, the environment will remain dry enough that strong to severe storms are not expected. Cloud cover will generally increase across North Dakota this evening, becoming partly cloudy in the north to mostly cloudy in the south. Winds are anticipated to remain generally light, though could become gusty where thunderstorms do develop. A more substantial shortwave disturbance will dig into the forecast area late tonight and into early Friday, expanding the chances (30 to 40%) across much of the state. The best forcing will push through the forecast area through the mid morning hours, promoting some chances for isolated thunderstorms across portions of the southwest and south central. While model bulk shear values do lie in the 25 to 35 knot range at this time, strong capping will is currently expected to inhibit the development of stronger storms at this point. Later in the afternoon, the erosion of the cap over portions of the south central and James River Valley, moderate low level saturation ahead of the trough, and some bonus forcing from low level convergence could allow a stronger storm or two to develop across this region. Were stronger storms do develop, we could see some strong gusts approaching 45 to 55 mph and small hail. Our current expectation for severe weather remains low, however, as model bulk shear values steadily decrease to around or even below 20 to 25 knots by the early afternoon period which, when paired with a fairly skinny CAPE profile in model Soundings and a moderately dry mid level forecast at around 50% humidity, indicates that any stronger storms will likely have trouble sustaining themselves. This expectation is reflected by both the SPC and CSU keeping the severe potentially mainly across the South Dakota border, where the ingredients are somewhat more favorable. The showers and thunderstorms that do develop should move southeast out of our area by the early evening hours. Partly to mostly cloudy skies will linger through much of Friday, before beginning to clear in late evening once the showers and storms move off to the southeast. Otherwise, highs on Friday are forecast broadly in the 80s, though some locations in the far west could approach the lower 90s. This weekend, chances for showers and thunderstorms will be possible in the afternoon hours as the occasional shortwave travels down the approaching upper level ridge. Then, mainly dry conditions are anticipated through much of next week. Highs each day through the weekend and into early next week are expected to be fairly seasonable, broadly in the 80s through Monday. By Tuesday, the development of another ridging pattern across the western CONUS will begin to promoting highs from the mid 80s to the lower 90s across much of western and central North Dakota through the later half of next week. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 655 PM CDT Thu Jul 18 2024 Isolated showers and thunderstorms are expected tonight into Friday. With the isolated coverage, only mentioned the possibility for thunderstorms in a few of the TAF sites which had the best chances for a thunderstorm to affect the airfield. Otherwise, VFR conditions will prevail. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...JJS DISCUSSION...Adam AVIATION...JJS