311 FXUS63 KFSD 170322 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 1022 PM CDT Wed Apr 16 2025 .KEY MESSAGES... - Warm, dry, and breezy conditions this afternoon. Elevated to near critical fire danger continues through early this evening. Area at highest risk resides east of I-29. - Showers and thunderstorms return Thursday morning into Friday morning. Some of these storms may become strong to severe. The better chance for strong to severe thunderstorms is Thursday afternoon. Area at highest risk for strong storms is southeast of a line from Yankton South Dakota to Marshall Minnesota. - Periodic low precipitation chances and near normal temperatures return for the weekend into early next week. && .DISCUSSION... Issued at 316 PM CDT Wed Apr 16 2025 THIS AFTERNOON-EVENING: Warm and breezy with south-southeast winds this afternoon. Winds will decrease through the late afternoon to around 10 mph. Temperatures in the mid to upper 70s will cool down to lows in the 40s and 50s. Conditions this afternoon are near critical for fire danger. However, southerly winds are transporting moisture northward. As dew points increase, winds are expected to decrease. The worst conditions are expected east of I-29, where occasional gusts of 25-30 mph may create temporary periods of critical fire conditions. Please continue to use caution with sources of sparks. THURSDAY: Early Thursday morning a midlevel shortwave and a band of positive vorticity advection will move through the area bringing low chances (<30%) for morning precipitation. As mentioned in previous discussions, the atmosphere will be strongly capped. The most likely storm initiation will be elevated along the 700 mb front. Here there resides between 500-1000 J/kg MUCAPE sufficient to support the development of isolated to scattered showers and thunderstorms. As the nose of the LLJ pushes briefly into the area, an increase in shear to around 35 kts, and steep midlevel lapse rates of 7.5-8 deg C/km could support formation of hail up to around an inch. As the surface low and cold front move through the region Thursday afternoon another round of showers and thunderstorms is possible. Highs will depend on timing of the frontal passage, but in general highs should be in the 60s west of the James River Valley, and the 70s to the east. Lows will fall to the 30s and 40s. For Thursday afternoon model soundings continue to show a well capped environment. However, if we manage to break the cap, there is 1000-1500 J/kg of MUCAPE available. Bulk shear increases to 40-50 kts with lapse rates of 7-7.5 deg C/km. If we break the cap, storms may quickly become strong to severe Thursday afternoon. Hail of 1 to 1.25 inches is possible, as well as wind gusts of 60 mph. Coverage of stronger thunderstorms looks to be southeast of a line from Yankton, South Dakota to Marshall, Minnesota. CAMs do not agree well on the timing or location of storm initiation, but the most likely timing will be between 4 and 10 pm Thursday afternoon/evening. FRIDAY - EARLY NEXT WEEK: Showers linger through Friday morning, before drying out Friday afternoon. Winds will be northerly and breezy, gusting 30-35 mph. Highs will be cool in the upper 40s to mid 50s. A large mid to upper trough moves east through the region this weekend. By Sunday the associated surface low is expected to move to the southeast of our region. There remains high uncertainty in track of the low, which will impact our chances for precipitation Sunday afternoon. As we head into next week, a series of waves through mostly meridional flow will keep periodic chances for precipitation in the forecast. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1018 PM CDT Wed Apr 16 2025 Scattered mid-lvl and upper clouds continue to move northeast late this evening. Eventually a few showers or even a thunderstorm may develop in SW Minnesota with this activity. An additional surge of mid-lvl clouds arrives around daybreak, bringing a risk for sprinkles elsewhere through mid-morning. Gusts ahead of a surface front moving into southeastern South Dakota may approach the 30 mph mark into early afternoon. Eventually this front will reach Sioux Falls around 19-20Z turning winds west of the front to the west and then sharply northwest. East of the boundary, scattered strong thunderstorms may develop over SW Minnesota and NW Iowa into early evening. Greatest potential from Sioux City to Windom. MVFR stratus may begin to move southeast into the Tri-State area in the evening, as gusty northerly winds continue. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...AJP AVIATION...Dux