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FXUS63 KARX 250158 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 855 PM CDT Wed Apr 24 2024 .KEY MESSAGES... - Frost/Freeze Headlines are in effect for portions of southwest Wisconsin tonight through early tomorrow morning. - An active weather pattern returns for the end of the week into the weekend with periods of rain and thunderstorms. Will continue to refine details revolving around the risk for strong to severe storms. && .DISCUSSION... Issued at 256 PM CDT Wed Apr 24 2024 Tonight - Tomorrow: Surface high pressure will continue to slide eastward through the period. With temperatures dropping around freezing to sub-freezing for some areas across southwest WI, have issued a frost/freeze headline for tonight through 8 AM Thursday morning. Another dry day is expected tomorrow with afternoon relative humidity values dropping into the 20 to 30 percent range, lowest east of the Mississippi River. In addition, as we find ourselves in between the departing high and an incoming low pressure system, southeast winds will begin to increase across the region, especially as we head into tomorrow night and through the weekend. Tomorrow Night - Weekend: As has been advertised, an amplified upper level pattern is forecast for the end of the week and weekend as upper level ridging builds to the east and troughing to the west. Will be keeping an eye on a couple of shortwaves moving across the region, bringing increased chances for rain and thunderstorms across the forecast area through the period. Overall, precip amounts The aforementioned trough over the southwest U.S. on Thursday is forecast to take on a negative tilt as it moves into the Central Plains by Friday. In turn, a surface low is forecast to lift northeast from the Central Plains towards the Great Lakes Friday through Friday night, with an associated surface warm front lifting northward ahead of the low. Moisture will begin to lift northward Thursday night into Friday with PWATs increasing to 1- 1.5" (90th percentile of climatology per NAEFS/ECMWF). This along with broad lift will allow for increasing rain and thunderstorm coverage across the forecast area Friday. There remain some uncertainties in the progression of the warm front and how earlier convection may have an impact. Even so, guidance suggests timing/location of the warm sector may be displaced to our south/southwest and in turn keeps the higher risk of severe weather southwest of the local forecast area. However, SPC does have portions of SE MN, NE IA, and SW WI in a marginal risk at this time, so be sure to stay up to date with the latest forecasts. The shortwave trough and surface low will continue to exit and weaken northeastward Saturday, leaving a boundary draped across the forecast area. There is some indication for a short break in precipitation for some Saturday. However, we will have to watch for redevelopment later in the day with plenty of moisture still in place. Model forecast soundings show capping in place through early Saturday, but if that can be eroded through the day some surface based convection may be possible east of the boundary. Another shortwave trough and surface low approach the region from the southwest Saturday night into Sunday. This will bring additional rain and thunderstorm chances to the forecast area. Details remain a bit less certain at this time, but this will be another time period to keep an eye on favorable conditions for severe weather. To note, SPC's Day 5 Severe Weather Outlook does highlight portions of NE IA and SW WI. Overall, with several rounds of precipitation over a few days ensemble guidance suggest rainfall amounts may fall in the 1 to 2-2.5 inch range, with probabilities for >= 3" remaining around 10- 20%. With the convective nature there will likely be some variability in exact amounts across the area, with some locally higher amounts possible. Will keep watch for any response/impacts to rivers with increased rainfall totals over the coming days. Next Week: Heading into next week, upper level ridging looks to build in across the central CONUS. There is still plenty of spread among ensemble solutions, but there is signal for a warm up into mid- week with the temp trend leveling out for the start of May. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 855 PM CDT Wed Apr 24 2024 CIGS: SKC/SCT conditions through the period. Next round of impactful/low cigs move in Friday morning as a spate of weather systems promise widespread rain/a few storms for the weekend. WX/vsby: no impacts expected. Next shot for rain with associated vsby restrictions moves in Friday morning with periodic -shra and a few ts through the weekend. WINDS: light southeasterly tonight increasing by mid morning Thu. A few gusts upwards of 20 kts for KRST. A stronger period of winds are expected for Friday through Sunday as a couple weather systems march across the region. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Frost Advisory from 2 AM to 8 AM CDT Thursday for WIZ053-054- 061. Freeze Warning from 2 AM to 8 AM CDT Thursday for WIZ055. MN...None. IA...None. && $$ DISCUSSION...EMS AVIATION.....Rieck