Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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576 FXUS63 KFSD 041857 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 157 PM CDT Tue Jun 4 2024 .KEY MESSAGES... - Scattered convection ahead of a progressive front will bring a limited risk for severe weather to portions of Minnesota and Iowa through 5pm. - Gusty west northwest winds to 45 mph likely Wednesday afternoon behind a frontal boundary. Advisory conditions may be briefly met at times, but diminish quickly by the evening. - Pattern shift the second half of this week will continue into next week. This pattern favors only modest precipitation chances (Saturday), but higher confidence for below normal temperatures and below normal precipitation across the 7 day period of time. && .DISCUSSION... Issued at 150 PM CDT Tue Jun 4 2024 THIS AFTERNOON: A quick moving frontal boundary is approaching I-29 as 2pm approaches. Large scale lift is beginning to increase, with the development of scattered thunderstorms ahead of the front. A narrow corridor of 1500-1800 J/KG MLCAPE persists ahead of the front, allowing for some deeper growth as storms move into Minnesota and Iowa. Deep layer shear remains marginal AOA 15-20 knots as storms develop, so the most likely outcome will be disorganized multi-cell clusters capable of marginally severe hail and a few isolated stronger wind gusts. TONIGHT: A deeper mid-lvl trough axis passes through the are overnight, which should scour out any lingering cloud cover. Winds will eventually turn westerly and remain light through the daybreak hours of Wednesday. WEDNESDAY: Weak mid-lvl warm advection forms near daybreak ahead of a secondary upper trough dipping into the Dakotas early in the day on Wednesday. Soundings show an increased layer of moisture AOA 700 mb, which may be capable of squeezing out virga, sprinkles or even a few light rain showers along and north of I-90 from daybreak through early afternoon. A stronger cold front quickly drops southward in the afternoon, reaching Highway 14 by early afternoon, I-90 by mid- afternoon, and Highway 20 by late afternoon. Deep mixing behind the cold front will promote both a risk for diurnal based CU/sprinkles, but also potential for gusts AOA 45 mph at times in the afternoon. A wind advisory may be needed for a brief period of time in the afternoon, but the overall strong wind risk is only a few hours. Prefer to mix in some of the deeper mixing models for peak wind gust guidance, which is an upwards deviation from the NBM. THURSDAY-FRIDAY: Mid-lvl heights begin to rise on Thursday. While temperatures rise into the 70s, we`ll again be dealing with a fairly breezy day. Forecast soundings indicate mixing upwards of 750 mb, which should result in fairly widespread afternoon gusts between 30 and 40 mph at times. We may begin to see more cloud cover and potentially an increase in rain chances late in the day on Friday. Medium range guidance remains very split, with some guidance showing the potential of a subtle wave moving through the ridge and weak warm advection showers by late Friday into Saturday. GEFS ensemble is the only ensemble really showing much potential of this taking place, with nearly 40% probabilities of 0.10" of precipitation. ECE/CME both suggest less than a 10% probability. For now, see no strong reason to deviate from the lower probabilities with the NBM guidance. SATURDAY-MONDAY: While uncertainty in the specifics remains fairly high, the broad pattern trends continue to support increased troughing over the Great Lakes and eastern third of the CONUS, with general northwesterly flow throughout the Northern Plains during the weekend and early next week. This pattern would favor dry, or nearly dry, conditions, with temperatures running near to even slightly below normal at times. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1202 PM CDT Tue Jun 4 2024 A progressive frontal boundary will slide eastward through the Tri-State area this afternoon. Ahead of the front, scattered showers and thunderstorms are likely to develop. A few strong storms are possible, mostly east of I-29. Brief periods of MVFR conditions are possible in convection. Skies will clear overnight as winds settle. Towards daybreak, scattered mid-lvl cloud field will arrive and could bring virga or scattered sprinkles to areas along and north of I-90. A front will then arrive in the afternoon, turning winds to the northwest and becoming rather gusty. Periods of 40 mph winds are possible through the afternoon. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...Dux AVIATION...Dux