Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
140 FXUS63 KMKX 221000 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 500 AM CDT Sat Jun 22 2024 .KEY MESSAGES... - Flood Watch continues for flash flooding potential across portions of south central and southeast Wisconsin through late this evening. Multiple additional rounds of showers and storms are expected, with widespread rainfall amounts between 1 and 3 inches and locally higher amounts exceeding 3 inches. - There is the potential for strong to severe thunderstorms this afternoon/evening (risk 2 out of 5). Damaging winds are expected to be the primary hazard, with isolated tornadoes and a few areas of large hail possible. - Heat index values in the upper 80s to low 90s are expected across far southern Wisconsin today, with heat index values reaching 90 degrees across much of southern Wisconsin again on Tuesday. - Strong thunderstorms may develop once again along a cold front on Tuesday. && .SHORT TERM... Issued 500 AM CDT Sat Jun 22 2024 Today through tonight: Scattered showers and thunderstorms are ongoing along the nose of an 850 mb LLJ, pushing northeastward through the mid-morning hours. Warm frontogenesis north and west of the I-90/I-94 corridor will allow for scattered to isolated showers and storms to linger through the day, while areas to the south may even see brief breaks in cloud cover and temperatures rising into the upper 80s in far southern Wisconsin. With high humidity, heat index values in far southern Wisconsin may rise to near 90 degrees. PWATS of 2 to 2.25 inch will lead to heavy rainfall rates and wet microburst potential within any thunderstorms that develop. However, storms will be moving quickly northeastward. Therefore, training convection will be needed to realize flash flooding potential. A Flood Watch remains in effect due to multiple additional rounds of rainfall over already wet soils. This watch is valid through midnight CDT tonight to account for any lingering precipitation after cold frontal passage. Low pressure strengthens over northern Wisconsin late this afternoon, developing and pushing a strong cold front southeastward through southern Wisconsin late this afternoon into tonight. This cold front will be pushing into a primed airmass with CAPE of 1000 to 2000 J/kg, 0 to 3 km SRH of 200 to 300 m2/s2, and minimal CIN. PWATs on the order of 2 inches, a 700 mb jet, and at least a few hundred J/kg of DCAPE lends credence to widespread damaging wind potential along the line. QLCS tornadoes are also a potential as line normal shear may be up to 40 kts in places while SRH of 200 to 300 m2/s2 continues. Storms exit offshore into Lake Michigan into the early overnight hours, with northwesterly breezes thereafter. MH && .LONG TERM... Issued 500 AM CDT Sat Jun 22 2024 Sunday through Friday: A quiet day on Sunday, with a few isolated showers and thunderstorms in southeastern Wisconsin during the afternoon hours (15% chance) as a shortwave passes through. Northwesterly breezes continue, with highs near 80 degrees. High pressure then dominates through Monday, allowing temperatures to rise again into the mid-80s. Tuesday, low pressure propagating eastward through the Canadian provinces will shift winds southwesterly and bring in high heat index values and high humidity once again. A frontal feature associated with this low is expected to bring showers and thunderstorms. A few storms may be strong to severe, with increasing CAPE and PWATs through the day. Longwave ridging across the Southeast U.S. and Appalachia may permit the frontal boundary to stall through Wednesday morning before weakening, bringing additional rainfall to southern Wisconsin. High pressure and seasonable temperatures are then expected Wednesday through late week, with an additional Canadian low producing thunderstorm chances Friday. MH && .AVIATION... Issued 500 AM CDT Sat Jun 22 2024 Scattered showers and thunderstorms are producing visibilities between 3 and 5 SM. Strong thunderstorms are producing visibilities around 1 SM. Meanwhile, light onshore flow and humid conditions have lead to patchy dense fog along the Lake Michigan lakeshore. IFR Ceilings near Lake Michigan and near MSN reflect lifting fog, with ceilings rising into MVFR/VFR beneath showers and thunderstorms. Scattered showers and thunderstorms will give way to more widespread showers with embedded thunderstorms in southwestern Wisconsin later this morning, while terminals near Lake Michigan may see a break in precipitation this morning into early this afternoon. MVFR to VFR conditions are expected during this time frame. During the late afternoon to late evening hours, a strong line of thunderstorms is expected to progress southeastward across southern Wisconsin, producing damaging winds, isolated tornadoes, and heavy downpours. Northwesterly winds are expected after the line exits. MH && .MARINE... Issued 500 AM CDT Sat Jun 22 2024 Light winds will transition to southerly and gusty across the southern two-thirds of the open waters and to easterly and gusty across the northern one-third this morning into this afternoon as low pressure develops in southern Minnesota. This low will progress through northern Lake Michigan this evening into tonight, bringing widespread thunderstorms along a cold front. Gusty winds are expected with these thunderstorms, especially in the southern half of the lake. Winds may approach Small Craft Advisory criteria tonight after the line of storms moves into the open waters. Winds across the Lake then shift northwesterly late tonight into Sunday morning as storms end. Winds will diminish but remain northwesterly through Sunday night, with high pressure building in Monday and producing light and variable winds. MH && .MKX WATCHES/WARNINGS/ADVISORIES... WI...Flood Watch...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-WIZ058- WIZ059-WIZ062-WIZ063-WIZ064-WIZ065-WIZ067-WIZ068-WIZ069 until midnight Sunday. 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