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Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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312 FXUS63 KARX 150404 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 1104 PM CDT Wed Aug 14 2024 .KEY MESSAGES... - From Tonight into Thursday morning, there will be a round of showers and storms. Some of these could produce heavy rain. - From Thursday afternoon into Thursday evening there will be an additional round of showers and thunderstorms. While rain rates look to be less, there could be some strong to severe storms. This is highly dependent upon afternoon cloud cover. && .DISCUSSION... Issued at 319 PM CDT Wed Aug 14 2024 Tonight through Thursday night... The 14.12z models continue to show that a low pressure system will move slowly east northeast through the area and gradually deepen. Even though it will be deepening, the 0-6 km shear is rather messy. This is especially the case in the 3-6 km shear. The 0-3 km shear look a bit better, but its shear is in the 20 to 30 knot range. Unlike yesterday, there appears to be a bit more instability in the wake of the morning convection. Many of the models are suggesting 1-2K J/kg 0-1 km CAPES. There are even a few models up to 2500 J/kg. This will all depend on the cloud cover during the afternoon. In addition, there will be some moderate to steep mid-level lapse rates. This could result in some pulse severe storms, so the marginal Day 2 SPC outlook looks reasonable. With precipitable water values increasing to around 2 inches and warm cloud depths of 3.5 to 4 km, these showers and storms will be highly efficient rain producers. WPC has the area under marginal risk for excessive rain. It continues to look like most areas will see anywhere from 0.75 to 1.5 inches of rain. The 24-hour HREF QPF ensemble localized probability matched mean has an area of 2-3 inches from northeast Iowa northeast into north-central Wisconsin. Friday... The 14.12z models continue to show that surface low will continue to move east northeast into the northern Great Lakes. This will keep scattered showers and maybe a few storms as shortwaves rotate around this low. With limited instability and the best moisture to our east, rainfall totals still look to be on the lighter side. Days 8 to 14 (August 22-28)... Unlike the past several days, it looks like there will be a far less amplified 500 mb pattern across the northern United States and the Canadian Prairies. As a result, it is looking like the omega high in the 6 to 10 day period will quickly flatten as a series of shortwave troughs move through this region. Northwesterly flow aloft will bring unseasonably cool air south into the region. As a result, the chances for below-normal temperatures have increased across the Upper Mississippi River Valley east into the Great Lakes. While the temperatures look a bit cooler, there continues to be enhanced chances for drier than normal. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1105 PM CDT Wed Aug 14 2024 Scattered showers will continue into the early morning hours. Shower coverage is expected to increase as a band of precipitation moves through the area roughly between 07Z and 15Z. As coverage increases, there is an increased chance for thunderstorms to occur, between 20 and 40%. After this band exits the area, scattered showers will remain in the area into the afternoon before scattered thunderstorms become possible through the afternoon. CIGS will lower into MVFR/IFR flight categories during the overnight before going back to VFR for Thursday afternoon. Predominant southeast winds through Thursday morning before shifting more westerly for the afternoon and evening. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Boyne AVIATION...Cecava