Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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175 FXUS63 KFSD 130337 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 1037 PM CDT Wed Jun 12 2024 .KEY MESSAGES... - Another round of scattered light showers and thunderstorms move across the region during the late overnight hours into Thursday morning, with afternoon temperatures again in the 80s. Severe weather is not expected. - Near to above normal temperatures will continue, with daily highs expected to peak the upper 70s to 80s. - Confidence continues to increase in more widespread rain chances on Saturday, with periodic chances for additional rain continuing into the early parts of next week. && .DISCUSSION... Issued at 252 PM CDT Wed Jun 12 2024 While we had scattered to areas of showers and thunderstorms earlier, temperatures have had no problems rebounding back up into the mid to upper 80s across the region. This is occurring as temperatures aloft continue to exceed the 90th percentile of climatology, so with a couple hours left of sunshine, we could still see areas reach up into the lower 90s before the afternoon is over. While the earlier thunderstorms were caused by the prefrontal trough, the cold front itself is still poised to move through the area later this afternoon into the evening hours. However, the front itself does not look to create enough lift to overcome the 50-100 J/kg of convective inhibition (CIN) created by the warm-air advection aloft. So, while we would have 2000-3000 J/kg of CAPE and 45 to 50 knots of bulk shear available to any storm that is able to break through the cap, additional severe thunderstorm development appears unlikely as the cap is expected to remain in place. As we cooldown to our cross over temperatures tonight, we may see some patchy fog develop in low-lying areas and river valleys, but overall widespread fog is not currently expected. Otherwise, winds will be light and variable tonight, with overnight low temperatures largely in the 60s expected. A weak shortwave moves across the region late overnight into the morning hours, but as dewpoints drop down in the 50s and low MUCAPE values of a 100-300 J/kg, only expecting light rain before the showers exit off to our east. Above normal temperatures in the lower to upper 80s are still expected for Thursday, as the cold front largely lowered our dewpoints. Upper level ridging occurs off to our west overnight into Friday, with a surface high pressure sliding down from Canada during the early morning hours. This will keep us closer to our normal temperatures, in the lower to mid 80s. Upper level ridging breaks down throughout the day as a potent shortwave ejects onto the central plains from the rockies, with the first of many shortwaves moving across the area by Friday evening. SPC has issued a level 1 out of 5 risk for severe thunderstorms. As additional waves move overhead, periodic chances for showers and thunderstorms continue throughout the day on Saturday, before ending on Sunday morning. The pattern remains active into the beginning of next week as southwesterly flow aloft continues due to a strong upper level ridge expected to develop along the east coast. This sets us up to potentially see periodic chances for rain as numerous shortwaves move across the region, with the inverted trough from a surface low pressure system also focusing chances for rain across the region. Model solutions have similar ideas, but do vary in their placement of warmest temperatures and highest rainfall chances, so have left the NBM in place given the uncertainties. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1031 PM CDT Wed Jun 12 2024 Scattered showers and isolated storms possible late tonight through Thursday morning, with the best chances along/north of I-90. Have added some VCSH for KHON toward daybreak, but confidence is low enough to omit from KFSD. Light, variable winds tonight could lead to patchy fog in low areas; however, uncertainty in coverage/development keeps confidence too low for inclusion at this time. Winds increase and shift northerly during the day on Thursday, when gusts around 20 knots are expected. Winds drop off again Thursday evening after sunset. Outside of aforementioned showers/storms and patchy fog (both of which could drop ceilings or visibility to MVFR or lower), VFR conditions prevail through Thursday evening. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...APT AVIATION...SG