Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
508 FXUS63 KMKX 240335 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 1035 PM CDT Thu May 23 2024 .KEY MESSAGES... - Two rounds of showers and thunderstorms will likely occur from Friday morning into Friday evening. There is a slight risk for severe storms (2 out of 5) Friday, mainly for hail and gusty winds, although a brief, isolated tornado can`t be ruled out. && .UPDATE... Issued 1021 PM CDT Thu May 23 2024 Conditions will remain quiet through most of the overnight. Most 00z model runs favor a dying line of thunderstorms moving toward the lakeshore in the morning to early afternoon on Friday, with redevelopment in the afternoon and evening causing most of the severe weather threat for tomorrow. Of note, the HRRR does depict an unstable sfc environment lifting north ahead of the morning line of storms. While this appears to be an outlier solution compared the the Nam 3km and WRFs at the moment, if this solution were to pan out, there could a brief window for severe weather with the morning round inland from Lake Michigan before the line weakens as it moves toward the lake. We`ll continue to monitor this potential outcome overnight, especially as models get a better handle on the MCS forming over the Central Great Plains. CMiller && .SHORT TERM... Issued 234 PM CDT Thu May 23 2024 Tonight through Saturday: Broken high based cumulus and isold showers have formed north and west of Madison as a weak shortwave trough moves across central WI. Isold to sct showers and isold storms will remain possible north and west of Madison toward east central WI the remainder of the afternoon. Upper ridging and quiet wx is then expected tnt. For Fri, a negative tilt upper wave and associated sfc low will move from the ern Dakotas into Canada while deepening then occluding. A surge of low to mid level warm, moist advection and elevated CAPE will bring a 1st round of showers and storms from west to east across srn WI Fri AM into the early afternoon, with some weakening expected in the east, especially toward east central WI. A few hours or more of decreasing pcpn coverage and the nwd advance of the warm front is then expected over srn WI before the cold front arrives from late afternoon into the evening. There is uncertainty on the airmass recovery and the amount of MLCAPE and MLCIN within the narrow warm sector, but believe MLCAPE of 1000 J/KG is very probable while some MLCIN will remain. However some PVA should aid the frontal forcing and the HREF suggests another round of storms. Deep layer shear will range from 30-45 kts while 0-2km SRH will likely be rather high around 200-300 m2/s2 as veering profiles remain in the narrow warm sector. As the fronts advance the lake breeze should eventually retreat toward the lake but early afternoon convection could reinforce it as well. All SVR threats will be possible with supercellular development and/or QLCS development. If the airmass recovery suffers, any meaningful MLCIN would keep the tornado threat rather small. Nwly winds and cold advection will then drop temps into the middle 40s to lower 50s by sunrise Sat. High pressure will then shift across the state on Sat with temps rebounding into the lower 70s for the afternoon. Gehring && .LONG TERM... Issued 234 PM CDT Thu May 23 2024 Saturday night through Thursday: High pressure is expected to shift east of the region Saturday night, as low pressure moves across Kansas. The low track is generally northeast into far northern Illinois or southern Wisconsin Sunday, before moving into northern Lake Michigan Sunday night. Ensemble low track trends have been shifting a little northward, so a track across far southern Wisconsin is possible Sunday afternoon and early evening. Warm air advection ahead of the low will bring deep moisture into the area, and should bring clouds and showers/thunderstorms into the area Sunday morning into the afternoon. There may be a couple of shortwave troughs that rotate through the area as well, as the main 500 mb remains northwest of the area. The main question will be if and how much instability may develop if the warm sector airmass can push into southern Wisconsin, given the northward trend on the ensembles with the low track. There is enough deep layer bulk shear to bring some severe storm potential, so instability will be key. The further north the low can track into southern Wisconsin, the better the severe weather potential may be. Kept the higher PoPs for Sunday into Sunday evening for now. Warm temperatures are expected to continue. Another 500 mb shortwave trough may shift southeast through the region Monday or Monday night/Tuesday, with the area getting into more northwesterly flow. Some semblance of a cold front may shift southeast through the region on Tuesday as well. Thus, kept PoPs for showers and a few storms going for most of this period. High pressure should bring back quiet weather for mid-week. Temperatures via ensembles and NBM still look rather mild into next week. Wood && .AVIATION... Issued 1034 PM CDT Thu May 23 2024 Mainly VFR overnight with southeasterly winds. Clouds will increase overnight and lower in height to low VFR as an MCS moves in from the central plains. Rain and thunderstorms will be possible between 12z and 18z as the line moves from west to east tomorrow morning. Another round is expected to develop tomorrow afternoon and move through from west to east between 18 to 21z through 03z. Hail and gusty winds will be possible with these storms. CMiller && .MARINE... Issued 234 PM CDT Thu May 23 2024 High pressure around 29.9 inches will drift across the Great Lakes this afternoon into tonight. Light to modest southerly winds will prevail over the entire lake becoming easterly late tonight. Modest east-southeast on Friday are expected as a warm front approaches followed by a cold front Friday night. A couple rounds of thunderstorms are expected with the fronts. Modest westerly winds will occur after the cold frontal passage and continue into Saturday. High pressure around 29.9 inches will then move across Lake Michigan for Saturday afternoon and evening. 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