Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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732 FXUS63 KARX 070304 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 1004 PM CDT Sat Jul 6 2024 .KEY MESSAGES... - Intermittent showers/storms are possible through the middle of the coming week, although most hours will be dry. Overall, the risk for organized heavy rain/severe weather is low. - Temperatures likely will remain near to below average through much of the coming week, possibly warming back above average towards next weekend. - The Mississippi River is near crest south of La Crosse to Guttenberg, IA, and is slowly falling to the north. By early next week, falling river levels are expected along the Upper Mississippi River from southwest WI/northeast IA northward. && .DISCUSSION... Issued at 145 PM CDT Sat Jul 6 2024 This Evening - Sunday: Broad mid-level troughing persists from the northern Plains through the Great Lakes this afternoon. GOES water vapor imagery showed an embedded shortwave across the northern plains, which will slowly progress into Minnesota over the coming day. Regional radar mosaics showed areas of showers/storms in association with this wave across the Dakotas into Minnesota as of early afternoon. Late this afternoon, lift is quite nebulous, but as inhibition is eroded, a small (10%) chance for a shower/storm exists, with the RAP indicating 1000-1500 J/kg MLCAPE from southeast MN into north- central WI. Heading into tonight and Sunday, modest moisture transport/warm advection ahead of the trough will spread across the area, with an attendant increased chance for showers/storms. With instability waning as rain approaches later this evening/tonight, expect showers and subsevere storms. Additional scattered storms are possible later Sunday/Sunday evening ahead of a weak boundary approaching from the northwest as weak inhibition is eroded by daytime heating. Although flow fields will increase relative to today, overall, modest instability (SBCAPE 1000-1500 J/kg) should be a mitigating factor for stronger storms, but gusty winds/small hail could not be ruled out with a few storms. Given the lack of deeper moisture and instability, the potential for heavy rains is limited, but any slower moving storms could produce localized amounts of 1 inch or more. Monday - Saturday: Weak mid-level troughing will persist through the first half of the work week across the Upper Mississippi Valley, keeping the region in a seasonably cool temperature regime. Additional showers/storms will remain possible (30-50%) on Monday, highest chances across Wisconsin near and ahead of the weak boundary. Additional showers/storms, primarily diurnal in nature, will be possible (20-50%) through mid- week given the weakly cyclonic mid/upper flow atop seasonable boundary layer moisture. With weak flow aloft, the risk for severe storms in this pattern looks quite low. Also, similar to this weekend, organized heavy rainfall potential is also low, but localized heavier rain amounts cannot be ruled out in slow-moving storms. Gradually building mid-level heights are forecast later in the week. As this occurs, temps should trend upward late in the week into next weekend, while rain chances trend downward (10-30%). && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1001 PM CDT Sat Jul 6 2024 Probability for showers and perhaps a bit of thunder continues to trend lower at RSE/LSE overnight. Have therefore removed the SHRA mention at LSE and continued to refrain from thunder mentions. Moving ahead to Sunday afternoon, continue to see a good signal in guidance for MVFR cumulus development and have therefore placed this into the TAFs for a few hours at each site. A shower or thunderstorm may develop out of this cumulus, but probability remains too low for a mention with this update. && .HYDROLOGY... Issued at 145 PM CDT Sat Jul 6 2024 The Mississippi River is near crest south of La Crosse and has been falling from near La Crosse and points north. By early next week, Mississippi River stages will begin falling across northeast Iowa/southwest Wisconsin. Off and on shower/storm chances are expected tonight and Sunday which could yield additional rainfall amounts of 0.1" to 0.25" with localized higher amounts. An unsettled pattern is expected to persist through the first half of next week, but rain amounts are generally expected to remain light. That said any thunderstorms could produce localized higher amounts over 1". && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...JM AVIATION...Ferguson HYDROLOGY...Naylor