Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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336 FXUS63 KFSD 090341 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 1041 PM CDT Wed May 8 2024 .KEY MESSAGES... - Widespread showers with embedded thunderstorms east of I-29 will transition to scattered showers overnight into Thursday morning. Some threat for localized heavy rainfall resulting in additional rises on some rivers/streams, mainly in northwest Iowa/southwest Minnesota. - Warmer and mainly dry conditions move in for the weekend. Continued warm with renewed rain chances by mid week. && .DISCUSSION... Issued at 239 PM CDT Wed May 8 2024 Showers and thunderstorms should increase in coverage across parts of northwest IA and southwest MN through the afternoon as well as near highway 14. A small axis of instability is expected this afternoon in this area. Overall instability not that high, but with the freezing level around 6-7 kft it will be pretty easy to get some smaller hail. Still looks like an environment supportive of hail up to half dollar sized with only weak shear expected. One other thing to watch will be the potential for funnels and landspouts. Steep low level lapse rates and lighter winds near a surface boundary may support this type of activity. With only marginal instability and weak shear any activity like this should be short lived. While some stronger winds gusts will be possible the HRRR and HREF both indicating gusts should generally be 50 mph or lower. The upper level low pressure shears out and sags south tonight into Thursday. Scattered showers will remain possible during this time, but instability is quite a bit less so even lightning will likely diminish quite a bit after about 10 pm. Lows will be seasonally mild in the mid 40s. While the main synoptic forcing settles south, model soundings do show some weak instability near the top of the mixed layer on Thursday which may support some isolated showery activity. Temperatures will also be a touch cooler as winds turn northerly and some diurnally driven cloud cover is expected to develop. Highs should still be in the 60s. Friday and Saturday will be dry and mild as northwest flow aloft weakens and westerly flow in the low levels is in place. By Sunday a weak wave in this flow could bring some isolated activity but for now this looks to be low impact. Highs should gradually warm from the lower 70s Friday to the lower 80s by Sunday. West to northwest flow aloft is expected Monday and Tuesday which should lead to a couple of warm days. While this pattern will not be a wet one, some spotty shower and thunderstorm activity will be possible. The most agreement appears to be Monday night into Tuesday morning. Wednesday into Thursday the models are indicating a strong upper level jet max diving into the Northern Rockies which should turn upper level flow more southwesterly and bring a better chance for showers and thunderstorms. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1041 PM CDT Wed May 8 2024 Thunderstorms near/east of US Highway 59 in northwest Iowa are expected to weaken further through the remainder of tonight, with thunder not expected to impact TAF locations. MVFR ceilings and brief MVFR visibility will be associated with the area of more persistent rain east of I-29 through early Thursday. Additional scattered showers will slide back to the south across southeast SD through Thursday morning, with mainly VFR conditions expected. The threat of thunder with this activity is too low to include in TAFs, though is non-zero and will be monitored. Any showers may still produce gusty winds, though prevailing winds will generally be at or below 15kt into Thursday morning, with occasional north-northwest gusts to around 20kt during the late morning and afternoon. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...08 AVIATION...JH