Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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105 FXUS63 KARX 240923 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 423 AM CDT Mon Jun 24 2024 .KEY MESSAGES... - Showers and thunderstorms return to the forecast tonight. However, there still remains quite a bit of uncertainty revolving around storm evolution. A Slight Risk (level 2 of 5) for severe weather remains across the area. Should everything come together and severe storms develop, a more widespread damaging wind risk may evolve. - Another brief break for mid-week before additional shower and storm chances return late in the period. Details to be refined in the coming days. && .DISCUSSION... Issued at 423 AM CDT Mon Jun 24 2024 Today - Tuesday: Bottom line up front... the environment is very favorable for severe storms tonight. However, there still remain some considerable questions on storm evolution (where, when, and even if). An upper level low will continue to move eastward across Canada today, with a surface low and attendant frontal boundaries advancing across portions of the region. Moisture will be on the increase into the area with surface dewpoint temperatures forecast to increase into the 60s to low 70s. Strong warm air advection will also be increasing from the southwest through the day. This along with steep mid level lapse rates will allow for strong instability to build in. However, strong capping is expected to be in place with the EML moving into the region. The latest hi-res model guidance continues to show various solutions on how storms may evolve. It is possible we could see some elevated showers develop early this evening with mid level saturation shown in forecast model soundings. However, an interesting signal to mention, that has been persistent in a few of the hi-res models, is for storms to develop and track across Interstate 90. With not much focus for lift and the strong capping in place, this seems to be the less likely scenario at this time (but not throwing it out as impossible). Highest attention turns a bit later where a more significant scenario may be possible where hi-res guidance shows storms developing and intensifying into an MCS. With this solution, storms would likely track around the capping in place/along the CAPE gradient. While there are varying solutions on the track and timing, ensemble consensus seems to favor tracking the complex southeast along the Interstate 94 corridor. Though there is some signal for the southern edge of the system to brush south towards Interstate 90. If this scenario does occur, a more widespread swath of damaging winds would be possible. Overall, will need to continue to monitor trends and guidance through the day. There is quite strong instability and shear to work with, so IF storms can develop tonight they are very likely to become severe. As we head into Tuesday confidence unfortunately does not increase much more. A cold front is forecast to drop down across the area with some model guidance suggesting further storm development. However, how storms evolve on Tuesday will likely depend on tonights storms. Especially as there has been some indication for the cold front to be forced further south quicker. SPC has maintained its Slight Risk (level 2 of 5) for southern portions of the local area for now with the given uncertainties and multiple possible scenarios. Mid-week onward: High pressure builds in across the region behind our early week system. This looks to offer another break in shower and thunderstorm chances, with a bit cooler temperatures for mid week. However, another low pressure system is forecast to move across the region towards the end of the week. This brings a return of showers and thunderstorms to the area. However, there still remains typical spread in ensemble guidance regarding overall details. Will hang with the latest blended model guidance for now, which increases chances Thursday night into Friday evening/night. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1057 PM CDT Sun Jun 23 2024 VFR conditions are forecast for Monday. However, during the evening hours, thunderstorms could develop over central MN and move southeast toward the airfields. There is very warm air above the surface which should favor thunderstorms to form further north and east - toward KMSP to KDLL and northeast generally. Wind shear profiles combined with the instability, should it be released, would form severe thunderstorms with large hail and mainly a damaging wind threat. For now, have decided to add VCSH and a VFR BKN cloud deck for Monday evening until confidence can grow in a given outcome. && .HYDROLOGY... Issued at 613 AM CDT Sun Jun 23 2024 Heavy rainfall over the previous couple of days has resulted in many area rivers and streams running high or in flood stage. Flooding concerns will last well into the week, with the Mississippi River also continuing to rise. Fortunately, little rainfall is expected into Monday. However, another round of showers and thunderstorms will be possible Monday night into Tuesday. Although some details are uncertain at this time, will need to monitor for any further potential hydro impacts with these storms. Please continue to reference the latest flood statements for additional updates and details. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...EMS AVIATION...Baumgardt HYDROLOGY...EMS