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Area Forecast Discussion
Issued by NWS Sioux Falls, SD
Issued by NWS Sioux Falls, SD
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266 FXUS63 KFSD 080824 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 324 AM CDT Mon Jul 8 2024 .KEY MESSAGES... - Scattered showers and thunderstorms possible this afternoon into the evening, especially areas east of I-29. While the threat for severe weather is very low, small hail and a brief funnel cloud is possible. - Isolated afternoon into early evening showers/storms continue through Wednesday. Severe weather is not expected. - Temperatures for the first half of the week will be on the cool side of average for this time of year. However, a big warm up is on the way by the weekend along with an increase in humidity. && .DISCUSSION... Issued at 320 AM CDT Mon Jul 8 2024 Areas of patchy, dense fog are possible this morning along and east of I-29. This will burn off quickly after sunrise. Mostly sunny skies for today, warming into the upper 70s to low 80s. With dewpoints in the low 60s, conditions may feel a bit muggier than we`ve experienced recently. Later this afternoon, there is a chance for some very isolated showers and thunderstorms. Precipitable water values of 1+ inches, and long skinny CAPE indicate these showers may be capable of producing brief, heavy downpours. As these showers will be spotty in nature, most areas will not see any rain, but those that do could see a few hundredths. Under any of the stronger storms a half inch may be possible. Though we have some mild instability in the form of a 500- 1000 J/kg of MLCAPE, strong forcing and bulk shear are lacking this afternoon, and so we are not expecting severe weather. However, water vapor imagery corroborates model guidance of an area of increased vorticity on the backside of the low pressure system that is slowly moving off to the northeast. In addition, the non-supercell tornado parameter increases to 1-2 along and east of I-29, especially over western Minnesota. This indicates that there is a possibility for some brief funnels this afternoon in that area. These should not touch the ground, but can be alarming when witnessed. Tonight, northwesterly winds will become light and variable, bringing another chance for some patchy fog Tuesday morning. Lows will be in the low 60s. TUESDAY-WEDNESDAY: The slow eastward progression of the upper low spinning over the Great Lakes will keep enough energy in place for low end chances of showers and thunderstorms during the afternoon and early evening hours both days. The area most likely to see showers is east of I-29. Temperatures will begin to warm into the mid 80s for highs, and dewpoints will increase into the mid 60s by Wednesday. THURSDAY AND BEYOND: As mentioned in the previous discussion, an upper ridge begins to build in Thursday and through the weekend. 500 mb heights rise as a large high pressure sets up over the intermountain west. As the high pressure builds in we will see highs increase a couple degrees every day until we get into the upper 80s and mid 90s by Sunday. Dew points also gradually increase into the upper 60s as southerly winds at the surface bring northward moist air from the Gulf. By Saturday and Sunday, areas of northwestern Iowa will see dew points in the low 70s. This will result in heat indices approaching the mid 90s. People with sensitivities may need to plan ahead for the hot and muggy conditions this upcoming weekend. This period will remain mostly dry, though there are several weak mid-level waves that may bring isolated shots of rain. Overall any precipitation that does fall will be minimal. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1025 PM CDT Sun Jul 7 2024 VFR conditions will continue for the duration of the TAF period. Taking a look across the area, any lingering showers will gradually continue to dissipate over the next hour or so. Otherwise, quieter conditions will return as lighter winds continue for the duration of the period. Lastly, lingering low level moisture could lead to some patchy areas of fog mostly along the Missouri River Valley tonight. However, confidence in occurrence is low at this time. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...AJP AVIATION...Gumbs