Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
060 FXUS63 KMKX 162021 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 321 PM CDT Mon Jun 16 2025 .KEY MESSAGES... - Scattered showers and storms may continue to slowly move eastward into western portions of the area into early this evening, with brief gusty winds and small hail possible. - There is some potential for a line of storms moving southeast toward and into the area this evening and perhaps into the overnight hours. They may be weakening as they move in, or they may dissipate before moving in. Lots of uncertainty here. - Chances for showers and thunderstorms at times through the rest of the week, with the better chances for stronger storms Tuesday afternoon into Wednesday night. - Very warm and humid conditions are looking more likely for the weekend into early next week. && .SHORT TERM... Issued 321 PM CDT Mon Jun 16 2025 Tonight through Tuesday night: The current scattered shower and thunderstorm activity across southwest Wisconsin should slowly spread east into western parts of the area into early this evening. This is being driven by 850 mb to 700 mb warm air advection and perhaps some frontogenesis response in this area. CAMs have been really struggling with grabbing onto this activity so far today. Brief gusty winds and small hail are possible, with deep layer bulk shear up to around 20 knots and mean layer CAPE of 1000 to 1200 J/kg. CAMs continue to show some potential for a line of storms generally weakening as they move southeast toward and into the area this evening, perhaps lingering into the overnight hours. There remains a lot of uncertainty here with if and how much thunderstorm activity will affect the area during this time. Some CAMs bring weakening activity into the area as it pushes through, with others weakening before it gets into the area or are dry altogether. Will maintain PoPs for this possibility, but again confidence is rather low with what may occur. The cold front will shift southeast into the area Tuesday, sliding south of the Illinois border by later Tuesday afternoon or Tuesday evening. CAMs have been trending more toward convection developing over northern Illinois, where the front meets the influence of a possible MCV/shortwave trough. The HRRR still develops convection in parts of the area in the afternoon, before shifting it to the southeast. There is uncertainty here as well with what may occur, so kept PoPs in the 30 to 50 percent range in the south parts of the area Tuesday afternoon. Mean layer CAPE of 1000 to 1500 J/kg with 20 to 25 knots of deep layer bulk shear are anticipated in the southern parts of the area, so gusty winds and hail are possible again. There is not much besides the front to provide upward vertical motion, which contributes to the uncertainty. The approach of the deepening surface low Tuesday night and warm air advection should bring a round of showers and storms into the area, perhaps not until after midnight Tuesday night. Kept 50 to 70 percent PoPs for later Tuesday night for now. Wood && .LONG TERM... Issued 321 PM CDT Mon Jun 16 2025 Wednesday through Monday: Low pressure should move northeast through the area Wednesday, then to the northeast Wednesday night. There is a well defined shortwave trough accompanying the surface low, along with better deep layer shear in the 30 to 40 knot range. The key will be if enough of the warm sector airmass can get into the area to allow for enough mean layer CAPE to bring a strong to severe storm risk. The better chances for this would be in the southeast parts of the area Wednesday afternoon and evening. Kept 70 percent or higher PoPs for now for this period. The heavy rainfall risk for Tuesday night into Wednesday night will depend on if the Tuesday afternoon/night convection develops and is widespread enough to combine with any thunder Wednesday into Wednesday night. The area can take some heavy rain initially, though the usual urban and low lying areas may have some issues, if the rounds of storms occur, which is a big if at this time. The 75th percentile of NBM is 1.75 to 2.00 inches, but a large spread remains in the 25th to 75th percentiles due to the uncertainty in what convection may occur. For now, will continue to monitor this potential. Warm air advection Thursday night into Friday night ahead of and with the warm frontal passage may bring another round of showers and storms. South to southwest winds then pick up, with very warm and humid conditions likely to occur this weekend into early next week. Ensembles suggest highs well into the 80s and perhaps breaking 90 degrees in some areas, with dew points into the upper 60s or lower 70s. Will continue to monitor this period as well for possible heat impacts. Wood && .AVIATION... Issued 321 PM CDT Mon Jun 16 2025 The current scattered shower and thunderstorm activity should shift eastward into western portions of the forecast area into early this evening. For now, may add in PROB30 groups for this activity later this afternoon and early evening for the Madison and Janesville terminals. Not sure if this will move all the way east to the rest of the terminals. Light south winds are expected into early evening, with a southeast lake breeze lingering for the terminals near Lake Michigan. Ceilings should remain above 3000 feet AGL during this time. There is some potential for a line of storms moving southeast toward and into the area this evening, perhaps lingering into the overnight hours. There is a lot of uncertainty here with if and how much thunderstorm activity will affect the area during this time. Confidence remains low, so will not mention in TAFs at this time. Winds will be light and south tonight, then southwest on Tuesday, as a cold front moves into the area from the northwest in the afternoon. Winds should shift west behind the front. There are chances for showers and storms with the front, mainly Tuesday afternoon and evening. Uncertainty here again with if and how much showers and storms develop during this time. Wood && .MARINE... Issued 321 PM CDT Mon Jun 16 2025 Low pressure around 29.5 inches will cross western Lake Superior tonight, and high pressure around 29.8 inches will settle into the Upper Midwest on Tuesday. Low pressure of 29.6 inches will cross eastern Iowa Wednesday morning and reach central Lower Michigan by Wednesday evening, while strengthening to 29.4 inches. High pressure of 30.0 inches will set up over the Plains Thursday, with the top of the ridge over Lake Superior and northern Lake Michigan. Expect increasing southerly winds tonight through Tuesday, with highest gusts over the north half of Lake Michigan. Lighter and variable conditions will return Wednesday, then become westerly Thursday. While showers and thunderstorms are possible through much of the week, the time period with the best chance for storms is Wednesday afternoon through Thursday morning. Cronce && .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