Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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765 FXUS63 KFSD 142322 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 622 PM CDT Sat Sep 14 2024 .KEY MESSAGES... - Wildfire smoke aloft is projected to linger over the region today, but trends pointing to improvement tonight into Sunday. - Isolated to scattered showers/storms impact mainly central to northeast South Dakota again later today-tonight, with a low (20%) chance mainly west of a Huron to Wagner line this evening. Gusty winds are possible with storms, but severe weather is not expected. - Temperatures remain above mid-September normals through much of next week, with nighttime lows showing greater departures above normal due to anomalously high low level moisture/dew points. - Greater chances for rain (50-80+%) return mid-late week next week, though details in exact timing/rainfall amounts are uncertain. && .DISCUSSION... Issued at 226 PM CDT Sat Sep 14 2024 Upper level troughiness will be in place today, with the better focus to the west of the area. With some marginal instability, CAPE values around 1000 J/kg mostly west of the Missouri River, a few thunderstorms may develop. Near and east of the James River there is less instability and stronger capping. Given the deep south to southwest flow any storms that do develop west of the area will struggle a bit to push eastward given the main storm motion will be in a northeast direction. So overall the main chances will be on the lower side, 20 to 30 percent chance, and mostly west of the James River. Some very weak, very elevated instability may allow for a few showers into the late evening and overnight towards I-29, but with a deep dry layer the impacts will be minimal. Warm overnight lows in the low to mid 60s, generally 5-10 degrees above normal, are expected with southerly surface flow continuing. A small chance for a little fog late tonight as well but confidence low. Sunday should be dry as the wave tonight lifts northeast of the area. A small tail of instability could tail into the area and produce very isolated showers or a thunderstorm but for now not thinking that will be a problem as everything looks capped. The exception could be near and east of the Buffalo Ridge into northwest IA where model soundings indicate the weakest capping. Southerly flow will be fairly strong with humidity a bit on the higher side, dew points in the lower to mid 60s, with highs topping out in the mid to upper 80s. Sunday night into Monday continues the warm southerly flow and only low chances for showers and thunderstorms. Lows in the 60s and highs in the 80s. Central SD will again see the slightly better chances for showers and storms, but still generally 20 percent or less. Monday night into Tuesday will see troughing mainly west of the area with the better chances for any showers and thunderstorms remain mostly west of the James River. Continued very warm with lows in the 60s and highs in the 80s. Tuesday night into Wednesday will be the next better chance for showers and storms. A wave will eject north into Montana with the tailing energy spreading into central SD. Still a few question marks with the upper level wave so far west. Right now the GFS and EC ensembles are showing about a 20 percent chance and 50 percent chance for a half an inch of rain Tuesday night into Wednesday west of I-29. Getting pretty far out, but looks like upper level ridging will move across the area Wednesday into Wednesday night, then the next piece of energy will move into the area Thursday with additional support for showers and storms Friday into Saturday, so for now looking like a busier time frame for precipitation next week. Highs remain mostly in the 80s through the week with lows in the upper 50s to 60s. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 621 PM CDT Sat Sep 14 2024 VFR conditions are expected for the TAF period. A complex of showers and storms over central South Dakota is drifting northeastwards this evening. Think the majority of the rain will miss KHON but have included VCSH for the first few hours of the TAF period. Trends will be closely monitored and amendments may be needed, including potential mention of thunder. Otherwise, light southeasterly winds will persist through the overnight hours before turning more southerly tomorrow morning. There remains potential for fog to develop across I-29 tonight. However, confidence remains too low to include in a TAF at this time. Southerly gusts up to around 15-25 knots will finish out the TAF period. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...08 AVIATION...Meyers