Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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450 FXUS63 KFSD 272105 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 405 PM CDT Sat Apr 27 2024 .KEY MESSAGES... - Periods of light to moderate showers return tonight and should continue into the day on Sunday. A few storms may become severe by Sunday Afternoon mostly across northwestern IA. However, the severe risk will be conditional. - An additional half inch to inch of accumulation is expected through Sunday night with isolated pockets up to 1.25 inches. Localized ponding in low lying or poor drainage areas will be possible. - An active weather pattern will continue through next week with periodic rain chances expected. However, precipitation chances and overall temperatures remain a bit uncertain. && .DISCUSSION... Issued at 401 PM CDT Sat Apr 27 2024 A mild and dreary day continues! Taking a look across the area, a layer of stratus continues to blanket most of the area as a quick mid-level ridge approaches the area from the southwest. Ahead of the ridge, lingering cold air advection (CAA) along with consistent cloud cover will keep temperatures fairly similar to yesterday with highs expected to peak in the mid to upper 50s and low 60s for the day with the warmest conditions expected across northwesterly IA. By tonight, our attention shifts to the southern Rockies as another Upper-Level Low (ULL) lifts northeastwards out of the Desert Southwest bringing our next precipitation chances. Looking aloft, mid-level warm air advection (WAA) will strengthen ahead of the inverted trough axis late tonight bringing our first round of showers mostly across northwestern, IA and the Missouri River Valley. However, with the better instability expected to be to the south and southeast of the area; most of the developing activity will likely stay sub-severe. Nonetheless, periods of moderate to heavy rainfall will be possible. As the main surface low continue to slowly rotate towards our area on Sunday, increasing isentropic lift and 700mb frontogenesis will lead to the development of more scattered showers and potentially a few thunderstorms. A few isolated storms could become severe by Sunday afternoon mostly across northwestern IA as the stratus potentially thins and the dry slot sets up. With decent instability (800-1000 J/kg) and 35-45 kts of shear, can`t rule out the potential for some quarter sized hail especially with mid-level lapse rates approaching 7 degrees C/km. However, this threat will be conditionally dependent on if the stratus can clear out and the atmosphere can recover enough from tonight rain chances for things to hold together. Nonetheless, as additional half inch to an inch of accumulation is expected across the area though Monday with localized ponding possible across poor drainage areas. Heading into the new week, any lingering showers will continue to lift northeastwards by Monday morning with the departing Upper Level Low (ULL). Breezy westerly surface winds will then return with gusts between 20-30 mph as a quick mid-level ridge moves over head. This combined with increasing WAA and effective mixing should help our overall temperatures slightly recover with highs expected to be in the mid 50s to low 60s for the day. A more active pattern will continue aloft starting Monday night as quasi-zonal flow brings multiple waves through the region over the course of the week. However, with timing and location differences among guidance decided to leave the default POPs in for the extended period. Lastly, mostly seasonal conditions will continue across the area into the weekend as daily highs peak in mid to upper 50s to low 60s. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1240 PM CDT Sat Apr 27 2024 A mix of MVFR and IFR conditions are expected this TAF period mostly due to lingering stratus and developing shower activity. Taking a look at satellite imagery, stratus continues to blanket the region as the Upper Level Low (ULL) pushes northeastwards into central MN. Expect the dreary conditions to continue throughout the day as a few areas of drizzle to sprinkles become embedded in the stratus. More rain showers will lift through the area overnight into the day on Sunday as another ULL pushes northeastwards. Otherwise, northwesterly surface winds will become more northeasterly overnight before becoming breezy again with gusts between 15-25kts possible through Sunday afternoon. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...Gumbs AVIATION...Gumbs