030 FXUS63 KFSD 071736 AFDFSD AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 1236 PM CDT Wed Jun 7 2023 .SHORT TERM...(Today and Tonight) Issued at 402 AM CDT Wed Jun 7 2023 TODAY: Early this morning, an area of showers and weak storms will continue to track south through western Minnesota. Waning instability with a passing weak disturbance in northerly flow aloft means continued isolated, high based showers and weak storms remain possible through mid morning in southwest Minnesota and mid day in parts of northwest Iowa. The fairly dry subcloud layer in model profiles suggests meager rainfall amounts of up to a few hundredths of an inch. A stagnant, dry upper level pattern persists today with upper ridging centered over the central Dakotas. Just east in the eastern Dakotas, a more unstable north to south oriented warm sector develops with a weak sfc trough/boundary draped from the Ohio River Valley back north paralleling I-29. This narrow warm sector situated amidst weak sfc convergence from the James River Valley to near the I-29 corridor becomes the focus for diurnally driven scattered showers and storms in the eastern Dakotas and Nebraska this afternoon, with greater coverage than the past few days. MUCAPE of 700-1700 J/kg, mid level lapse rates around 6 C/km, and precipitable water values of 1.5+ inches show potential for a few pulsy, strong to marginally severe multicell storms moving southerly. It will be difficult to sustain strong updrafts with deep layer (0-6 km) shear of only 20 to max 25 kts. Despite this, gusts up to 60 mph, hail up to quarter size, and local pockets of heavy rainfall cannot be ruled out with the strongest few storms from roughly 3-9pm. Aside from greater coverage of showers and storms by late afternoon, expect another day of above normal temperatures and further increased humidity with highs in the 80s (east of I-29) to the low to mid 90s (near/west of I-29). Aside from locally stronger, more erratic winds near showers and storms, prevailing winds will favor easterly east of I-29 and variable or slightly westerly west of I-29. TONIGHT: Shower and storm activity should weaken as instability wanes diurnally by mid evening. Could see see an occasional showers and weak storms overnight as the boundary remains in the region, but instability under 500 J/kg should negate any strong to severe storms from developing. Enhanced cloudiness overnight should keep temperatures on the warmer side, dropping into the 60s overnight and perhaps even 50s in drier air east of the boundary. .LONG TERM...(Thursday through Tuesday) Issued at 402 AM CDT Wed Jun 7 2023 THURSDAY: Expect slightly cooler, less humid conditions as Wednesday's warm sector and associated boundary shift further west into the central Dakotas and upper ridging weakens and regresses further into the High Plains. A shortwave tracking south through eastern North Dakota and into northeast South Dakota heading into Thursday evening will trigger a round of convection with some potential for severe weather, but this better forcing looks confined north of the Hwy 14 corridor. Cannot entirely rule out this activity working into east central South Dakota by the end of the evening, but diurnally driven activity seems unlikely with weak capping holding and lack of concentrated forcing for ascent. THIS WEEKEND: Confidence is increasing that the stagnant omega block across the CONUS breaks down by the end of the weekend. A strengthening wave rounds the upper ridge in northwest flow aloft and pushes a cold front into the eastern half of the U.S., giving a higher chance for scattered showers and storms Friday night through Saturday. Uncertainty in the low track and available moisture remains with ensemble guidance still painting a low chance (30% or less) of widespread rain exceeding 0.10". Guidance continues to favor cooler weather (i.e., highs in the 70s and 80s) for at least Saturday and Sunday as heights fall aloft. Sunday into early next week brings dry weather post-front amidst sfc high pressure. && .AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon) Issued at 1234 PM CDT Wed Jun 7 2023 Current satellite shows a CU field developing west of I-29 early this afternoon. Like what we have seen for the past several days, expect thunderstorms to develop within this CU field. A surface cold front has been pushing westward through the morning hours and now resides along the James River valley. This front may become a focus for thunderstorm development early this afternoon but could still see storm coverage expand east of the front. The bulk of the storms will be confined to around the James River and eastward towards I-29. As of now, confidence has increased in storm potential over KHON and have included VCTS in KHONs TAF. However, confidence has decreased a bit in storm potential at KFSD and KSUX. While still possible, have left any mention of thunder out of both KFSD and KSUX's TAF for this TAF cycle. Trends will be monitored and TAFs will be updated as needed this afternoon. Any storms that do develop will wane by this evening as the boundary layer stabilizes. With the area in the wake of the front, winds will remain light out of the east before slowly turning out of the southeast through the overnight hours to end the TAF period. Hi-res guidance does hint at the possibility of additional weak showers and storms overnight and tomorrow morning. However, confidence is not high enough to include in a TAF as of now. Will continue to monitor this possible development. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ SHORT TERM...BP LONG TERM...BP AVIATION...Meyers