Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
607 FXUS63 KMKX 200300 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 1000 PM CDT Wed Jun 19 2024 .KEY MESSAGES... - On and off thunderstorm chances will continue into this weekend. - Areas of fog (some dense) may develop over Lake Michigan tonight, and could drift into lakeshore counties tonight into Thursday AM. Patchy fog is possible further inland. - A break from the heat on Thursday, but heat index values will be back in the middle 90s Friday and Saturday. - A moderate swim risk is forecast Thursday morning at Sheboygan County beaches. Low swim risk for the afternoon and onwards. && .UPDATE... Issued 1000 PM CDT Wed Jun 19 2024 The effective front created by storm outflow has finished crossing the region, leaving the CWA in a weak northerly flow regime. Additional rounds of showers and weak thunderstorms are possible tonight (50% rain chance). Additional RH from overnight rainfall and / or radiational cooling through breaks in the clouds may lead to patchy fog development in our CWA overnight, dissipating a few hours after sunrise. Areas of fog (with patches of dense fog possible) could develop more easily over the cool waters of Lake Michigan, with northeast winds possibly advecting it into lakeshore counties Thursday AM. Lake Michigan wave height forecasts have trended lower, but the northeast winds and building waves Thursday morning are still expected to create Moderate Swim Risk conditions for Sheboygan county beaches. Wave heights decrease in the afternoon. Sheppard && .SHORT TERM... Issued 310 PM CDT Wed Jun 19 2024 Tonight through Thursday night: Cold front will continue to shift southeast through the area and into northern Illinois into this evening. Scattered showers and storms continue to develop and slowly shift northeast through parts of the area, both near the front and where convective temperatures may be reached. CAMs continue to support the scattered showers and storms into early this evening across the area. The best instability will be toward southeast Wisconsin, where mean layer CAPE up to 1500 J/kg or so is expected, perhaps higher in spots. Areas further northwest may have more clouds move in with the front, so mean layer CAPE there will be lower. 0 to 6 km bulk shear values should increase by early evening into the 20 to 25 knot range, though the southeast parts of the area will be on the lower end of this range. This would mean short-lived airmass thunderstorms that have some downburst wind potential, as forecast soundings are showing some inverted V structures to them in the low levels. In addition, cannot totally rule out a landspout spinup, as 0 to 3 km CAPE values are above 100 J/kg along the front and are coinciding with some surface vorticity with the front. The probability is low, but not zero. We will keep an eye on this. Heat index values in the lower to middle 90s are expected to linger in southeast Wisconsin until early this evening. Cooler but still mild temperatures are expected later tonight into Thursday, as winds shift northeast and lower clouds move in. Some fog and low stratus clouds may also push onshore near the lake overnight into Thursday morning. The clouds may linger for a good part of Thursday. Chances for showers and storms will continue at times overnight into Thursday night, as some modest 850 mb warm air advection and convergence/frontogenesis response lingers near the area. Areas near the Illinois border may see the best chances for storms Thursday afternoon and evening, as some better low level frontogenesis with the front just to the south of the area interacts with warm and unstable air. May see some gusty winds with any of those storms as well. && .LONG TERM... Issued 310 PM CDT Wed Jun 19 2024 Friday through Wednesday: Models are generally showing the warm front shifting north across the area Friday into Friday night, before moving further north for Saturday. Chances for showers and storms will remain during this period. The area should get into the warm sector and become very warm and humid again on Saturday with southwest winds. A cold front looks to shift east across the region Saturday night, bringing another chance for showers and thunderstorms. Will have to watch this period for stronger storms, though deep layer bulk shear values are only 20 to 25 knots at this time. There may be a lull in precipitation chances Sunday into Monday, as high pressure may move through the region. Temperatures look to remain near to above normal into next week per ensemble trends. Chances for showers and storms may return for the middle of next week as well, as ensembles are showing a generally wet Tuesday into Wednesday period. Wood && .AVIATION... Issued 1000 PM CDT Wed Jun 19 2024 Light north to northeast winds expected overnight. Patchy fog is possible for all areas, with the potential for areas of fog (some dense) over the southern half of Lake Michigan. Lakeshore county airports may see this denser marine fog and/or IFR stratus cloud ceilings drift inland due to the northeasterly wind. Though inland airports are farther from this marine layer, a west-to-east arrival of additional showers and weak thunderstorms overnight is likely to lower cloud ceilings to MVFR, with IFR possible. Off and on shower / thunderstorm chances continue into Thursday and this weekend. Cloud ceilings gradually improve throughout Thursday. Sheppard && .MARINE... Issued 310 PM CDT Wed Jun 19 2024 A cold front will gradually sink southeast across Lake Michigan into tonight. South to southwest winds will shift northwest to north this evening, and northeast to north later tonight into Thursday. Patchy to areas of marine fog may form tonight and linger into Thursday morning, with some dense fog possible. North to northeast winds should then linger into Friday, as high pressure around 30.4 inches moves from Lake Superior into Ontario. Gusty south to southwest winds are then anticipated to return for Saturday into Saturday night, as low pressure around 29.5 inches shifts into the region. Wood && .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