Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
190 FXUS63 KMKX 190316 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 1016 PM CDT Tue Jun 18 2024 .KEY MESSAGES... - Decaying thunderstorms with gusty winds will move into south central WI after midnight but more storms to follow later in the morning. Otherwise chances for storms (30 to 60 percent) will continue for Wed and the remainder of the week. - Dangerous swim conditions are likely into tonight at Lake Michigan beaches in Sheboygan and Ozaukee Counties. && .UPDATE... Issued 1016 PM CDT Tue Jun 18 2024 See no reason to veer away from the forecast of a decaying line of storms moving into south central WI after midnight. The low pressure area over ne MN will lift newd into Canada during the overnight with a weakening wind field and cold front. The MCS over IA is exhibiting front to rear flow and within weak deep layer shear so expect it to continue to weaken as it approaches WI. The gust front should still be able to initiate sct convection over south central WI for the early morning hours. Scattered convection could then continue from sw-ne on the tail end of the LLJ and just ahead of or along the slow moving cold front over south central WI for later in the morning. This will occur within a PW plume of 1.7-1.9 inches with some training of storms possible but believe any flash flood threat will remain low. The cold front will then slowly move sewd across srn WI through the day within the same high PW airmass. Scattered convection will likely reignite with heavy rainfall as the main hazard. A MCV or vorticity maximums will then approach srn WI from IA for Wed nt with possibly more heavy rain that could become better organized if a sufficient swly LLJ forms. Gehring && .SHORT TERM... Issued 324 PM CDT Tue Jun 18 2024 Tonight through Wednesday night: The low clouds have scattered out across the area, allowing for the very warm and humid conditions to take hold. Heat index values in the middle to upper 90s are generally expected inland from Lake Michigan until early this evening. A southeast lake breeze has developed near the lake, and those areas will cool down as a result. Peak temperatures will be close to convective temperatures, especially toward the Illinois border area. Isolated to widely scattered pop up showers and storms are still possible to occur in these areas. There is enough mean layer CAPE to possibly bring gusty winds with any storms. Deep layer bulk shear is quite weak, around 15 knots or less. So, would expect any showers and storms to be fairly short-lived. Beach Hazards Statement remains in effect until later tonight for the Sheboygan and Ozaukee County beaches. Gusty south winds will bring waves up to 4 feet for these beach areas, which will result in dangerous conditions for being in the water. A moderate swim risk remains for beaches to the south of there as well. There are better chances for showers and storms (30 to 60 percent) overnight into Wednesday night, as a cold front sags southeast into the area and washes out. There are some indications from the CAMs that the cold front could shift south of the area as well by Wednesday evening. Generally weakening showers and storms from the west overnight may shift into the western parts of the area. This may linger into Wednesday morning. CAMs generally support the weakening trend with this overnight and early morning activity. Clouds associated with this activity may linger through the rest of Wednesday, so there is uncertainty with how much instability will be available for possible storms later Wednesday into Wednesday evening. Deep layer bulk shear is expected to increase to 25 to 35 knots Wednesday afternoon and evening, so if storms can develop, there is some risk for strong winds from downbursts to occur. This will be conditional on clouds scattering out and enough instability developing. Heat index values may still reach the middle to upper 90s in far southeast Wisconsin, where the most sunshine could occur. Again, this will depend on if the clouds can scatter out by the afternoon. Wood && .LONG TERM... Issued 324 PM CDT Tue Jun 18 2024 Thursday through Tuesday: The upper flow will transition to nearly zonal between Wednesday night and Thursday as high pressure settles over the southeast US. Weak ripples in the flow will roll across southern WI and northern IL at times through Saturday. The effective front will waffle north and south a little, but overall we will remain in a warm and unstable pattern with at least small chances for showers and thunderstorms through the period. It looks like a stronger wave will cross the region Saturday and drag a weak cold front through southern WI Saturday afternoon or evening. This is a more certain time for storms, but the time of day will determine their severity so this is something to keep an eye on. There will be a brief period of northwest flow and a relief from the warm temps and storms Sunday into Monday night, but it looks like we will be warm again by Tuesday. Cronce && .AVIATION... Issued 1016 PM CDT Tue Jun 18 2024 MVFR Cigs will develop Wed AM over much of south central WI but especially where training of showers and storms occur. The MVFR Cigs should then rise to 3.5-5.0 kft for the afternoon and evening with scattered storms continuing over all of srn WI. Gehring && .MARINE... Issued 324 PM CDT Tue Jun 18 2024 Low pressure around 29.5 inches will move from west central Minnesota to near James Bay tonight. Gusty south winds are expected to linger tonight into early Wednesday. A Small Craft Advisory remains in effect through this evening for the nearshore waters, with the gusty winds and building waves. Gusts over the open waters will reach 30 knots at times into tonight, mainly over the northern portions of the lake. Some fog may develop at times over the lake into Wednesday, with the very warm and humid airmass in place. Winds will gradually ease Wednesday and shift to the north by Wednesday evening, as a cold front sags into the region. North to northeast winds should then linger into Thursday night, as high pressure around 30.4 inches moves into Lake Superior. Wood && .MKX WATCHES/WARNINGS/ADVISORIES... WI...Beach Hazards Statement...WIZ052-WIZ060 until 4 AM Wednesday. LM...Small Craft Advisory...LMZ643 until 1 AM Wednesday. Small Craft Advisory...LMZ644-LMZ645-LMZ646 until 10 PM Tuesday. && $$ 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