Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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506 FXUS63 KARX 141938 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 238 PM CDT Fri Jun 14 2024 .KEY MESSAGES... - Hot and humid Sunday into early next week with 60-90+% chances for 90F temps Sunday/Monday, especially south and west of I-94. - Showers developing on Saturday with some storms by afternoon into early Sunday. A few strong storms possible Saturday night into Sunday with hail/heavy rain the primary threats. - Highest shower/storm chances shift farther northwest late Sunday through early next week, but intermittent showers/storms are possible (20-50%). && .DISCUSSION... Issued at 239 PM CDT Fri Jun 14 2024 Shower/Storm Chances: Areas of showers will begin to increase on Saturday in response to mid-level warm advection, especially from parts of northeast Iowa and southeast Minnesota through north-central Wisconsin. By Saturday night, moisture transport and instability really begin to ramp up ahead of a stronger shortwave trough. This will result in areas of showers/elevated storms overnight into Sunday morning. Although shear above the stable layer is weak, the increasing instability and elevated mixed layer advecting eastward early Sunday morning could support some hail in stronger storms and any wind risk would be contingent on a more organized convective system surviving eastward into the area. In addition, precipitable water values exceeding 1.75" and warm cloud depths over 4 km could result in localized heavy rainfall, especially from northeast Iowa/southeast Minnesota through northern Wisconsin. Southwest flow aloft is expected through much of the week as the persistent ridging holds to the east. Within this pattern, the favored axis of heavy rainfall/higher rain chances overall currently looks to extend from southwest Minnesota/northwest Iowa northeastward into northwest Wisconsin with a gradient to the southeast across the Upper MS Valley. Late Sunday, abundant instability will be present, but the higher chances for storms may be closer to a surface boundary across central Minnesota. Little changes with the mean flow pattern Monday/Tuesday so rain chances are only 10-30% for much of northeast Iowa through central Wisconsin and 30-50% for southeast Minnesota into north-central Wisconsin, increasing moreso to the northwest. Confidence continues to remain low later in the week given the uncertainty in the evolution of the longwave pattern, including the ridge strength and surface boundary placement. Some strong/severe storms could not be ruled out given the thermodynamic environment through the week, but mesoscale details will impact day-to-day trends, and overall with the higher deep layer shear farther north and west across western Minnesota and the Dakotas, confidence in organized severe weather locally is low. Heavier rain may a concern, especially in focused areas of repetitive storm clusters over the course of the week, again favoring areas west and north. Temps/Heat: Mid-level ridging will amplify through early next week across the Great Lakes/Northeast with the Upper Mississippi Valley residing on the western periphery of the ridge. Assuming little impact from any showers/storms, both Sunday and Monday are favored for highs near or above 90F for much of the area. NBM probabilities for max temps at least 90F are 75-90% for areas southwest of I-94 on Sunday and 80- 90+% for much of the area on Monday outside of parts of northern WI and west towards I-35 in Minnesota. With favorable gusty southwest surface flow and 925 mb temps potentially climbing near 28-29C, max temps could climb at least into the mid 90s Sunday/Monday, closer to the NBM`s 75th percentile values. However, again, cloud cover and any areas of showers/storms could impact temps for some. Heat headlines could be considered for some areas if the higher values appear likely. Confidence is somewhat lower by mid-week given uncertainty in the ridge position and low-level boundary placement. Global ensembles show some signal for modestly lower temps for Wed/Thu. There are also indications that the ridge will retrograde west late in the week with any respite in cooler air short-lived, but there is considerable spread in outcomes/temps late in the week. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1231 PM CDT Fri Jun 14 2024 VFR conditions through the TAF period. Northwest winds will transition to southerly winds during the evening. Mid-level clouds will move into the region Saturday morning with CIGS between 7kft and 10kft expected. && .HYDROLOGY... Issued at 309 AM CDT Fri Jun 14 2024 An active period of weather is expected over the next week with chances of precipitation across the region expected virtually every day beyond Saturday. While the best chances of heavy precipitation remain off to our NW, there are still small chances of heavy rainfall across our area Saturday night (best chances along and north of an Austin, MN to Medford, WI line). Mean precipitation amounts through Wednesday range from around 2.5 to 3.5 inches to our NW across central MN and around 0.75 to 2.0 inches across our local area. While much of this precipitation is expected across multiple rounds, it will eventually route into the Mississippi River, which will likely keep the river elevated through at least the next two weeks. There is a 10% chance that the Mississippi River reaches Minor Flood Stage over the next 10 days through Winona (and roughly 25 to 30% chance at Wabasha). && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...JM AVIATION...Cecava HYDROLOGY...JAW