Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
093 FXUS63 KMKX 241536 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 1036 AM CDT Mon Jun 24 2024 .KEY MESSAGES... - A strong to severe line of fast moving thunderstorms is expected to move across southern WI after midnight. Damaging winds will be the main threat. - Urban and small stream flooding will be possible after midnight due to the already saturated conditions and a quick burst of torrential rainfall. - River rises will continue early this week and may receive a sudden boost from heavy rain after midnight. - Heat index values into the 90s will be possible on Tuesday. && .UPDATE... Issued 1036 AM CDT Mon Jun 24 2024 Main concern going into tonight will be MCS development across the Dakotas and Minnesota, with a probable southeasterly turn into the southern portion of the state. Exact track will be dependent on where exactly convection initiates and begins to congeal, but it seems more likely than not that at least portion of the forecast area will be impacted. Beyond that, the big unknown is how much wind will be able to make it through a low level stable layer. Above this inversion, very strong instability (2000-3000 J/KG of MUCAPE) is available. In addition, with PWATs between 1.5 and 2 inches, very heavy rainfall is likely with any storms. Storms could begin to impact the region as early as 10 PM, but right now midnight to 4 AM is the most likely window. Tonight`s activity will also have a significant impact on Tuesday`s convective potential, with remnant outflow serving as a focus for renewed development. This is currently expected to be near, or perhaps actually south of the state line, but will ultimately depend on how tonight`s activity plays out. Boxell && .SHORT TERM... Issued 431 AM CDT Mon Jun 24 2024 Today through Tuesday night: High pressure will shift ewd today with sly winds developing this afternoon. Any low lying fog will quickly burn off after sunset with temperatures returning to the 80s away from the lake for the afternoon. Attention then turns to a MCS for after midnight. A shortwave trough will track from wrn MN to the nrn Great Lakes tonight and be accompanied by a n-s wave of low pressure. A swly LLJ of 50 kt will develop ahead of the aforementioned features and then veer into srn WI after midnight. Strong warm, moist advection from 925-700 MB will support a maturing and fast MCS from ern MN esewd into srn WI. The strong thetae advection and steep mid level lapse rates will support elevated CAPE of at least 1500-2000 J/KG and PWs near 2 inches. Despite the elevated nature of this event, expect pockets of SVR winds to make it to the surface. The best timing for the MCS would be from 0600-0930 UTC. The sfc trough passage will then quickly follow on Tue likely setting up any new convection over IL and IA for later in the day. Wly winds and gradually lowering dewpoints will lead to a very warm day. Gehring && .LONG TERM... Issued 431 AM CDT Mon Jun 24 2024 Wednesday through Sunday: For Wed a digging shortwave trough will track from wrn Lake Superior and NW WI to the lower Great Lakes. Its cold front will pass in the morning including onshore flow from Lake MI. Despite these features the fcst soundings are fairly dry and will keep pcpn out of the fcst for now. Pleasant temps in the 70s are expected, but possibly only upper 60s for east central WI and near Lake MI. High pressure will then shift across the state late Wed nt into Thu AM. Another pleasant day in the 70s is forecast. Yet another round of strong warm, moist advection and thunderstorms arrive for Fri followed by a stronger cold front and more storms Fri nt-early Sat. This will be initiated by an upper trough and cyclogenesis moving from the nrn Great Plains to the nrn Great Lakes. Certainly cannot rule out SVR storms and heavy rain with this scenario. Weakening nly winds and pleasant temps and humidity for Sun with high pressure arriving late in the day. Gehring && .AVIATION... Issued 1036 AM CDT Mon Jun 24 2024 Light southerly winds and VFR conditions are expected during the day today. Tonight, one or more clusters or lines of thunderstorms are expected to impact the terminals, with strong winds, heavy rain, and low ceilings/vis possible. Winds will then likely turn variable for a time behind the storms, before becoming more westerly in nature for Tuesday. Some additional storms are possible on Tuesday, but these may remain south of the terminals. Boxell && .MARINE... Issued 431 AM CDT Mon Jun 24 2024 High pressure of 29.9 inches will shift east across Lake Michigan this morning with light and variable winds expected. Modest south winds will develop this evening, becoming breezy late tonight into Tuesday morning as low pressure around 29.2 inches moves across northern Ontario. Modest westerly winds behind the low will then shift to northerly on Wednesday following the passage of a cold front. A line of thunderstorms with very gusty winds will move across Lake Michigan late tonight through Tuesday morning. Gehring && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. && $$ Visit us at weather.gov/milwaukee Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSMilwaukee www.twitter.com/NWSMilwaukee www.youtube.com/NWSMilwaukee