Area Forecast Discussion
Issued by NWS La Crosse, WI
Issued by NWS La Crosse, WI
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433 FXUS63 KARX 241745 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 1245 PM 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 /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1245 PM CDT Mon Jun 24 2024 Thunderstorms will be the primary aviation concern late this evening and overnight as guidance continues to suggest a line of strong to severe storms progressing through the region. Uncertainty still remains with this line in both timing and location, however if short-range guidance does resolve (40-70% chance) would expect a period of MVFR/IFR conditions at KLSE, perhaps KRST as well, between 03z and 09z with the potential for very strong wind gusts to occur. VFR conditions are generally expected behind this line of storms aside from some indication for MVFR cigs (20-40% chance) during the early morning hours. Winds switch from southerly to northwesterly through the TAF period, remaining around 5-15 kts with higher gusts possible within thunderstorms tonight. && .HYDROLOGY... Issued at 610 AM CDT Mon Jun 24 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. Another round of showers and thunderstorms will be possible tonight into Tuesday. Although some details are uncertain at this time, locally heavy rainfall may be possible. With the already saturated soils, will need to monitor for any further potential hydro impacts as any additional heavy rainfall could exacerbate ongoing flooding. Please continue to reference the latest flood statements for additional updates and details. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Flood Watch from 7 PM CDT this evening through late tonight for WIZ032>034-041>043-053. MN...Flood Watch from 7 PM CDT this evening through late tonight for MNZ079-086>088-094>096. IA...None. && $$ DISCUSSION...EMS AVIATION...Naylor HYDROLOGY...EMS