Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
037 FXUS63 KMKX 170144 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 844 PM CDT Mon Jun 16 2025 .KEY MESSAGES... - A few showers and thunderstorms are possible through the overnight, but most locations will likely remain dry. - 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. && .UPDATE... Issued 844 PM CDT Mon Jun 16 2025 Convection across southeastern Minnesota and far western Wisconsin has struggled to become organized this evening, likely due to a lack of strong upper level support and weak/disorganized convergence in the low levels. A cold front currently located across this region will sink south- southeastward tonight into Tuesday morning, and while there will be chances for a few showers and thunderstorms during this time, coverage looks to be pretty sparse, and most locations will likely remain dry through the overnight hours. No severe weather is expected, though some brief gusty winds and small hail can be expected with the strongest storms. Boxell && .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 844 PM CDT Mon Jun 16 2025 Isolated thunderstorms will be possible during the overnight hours as a weak frontal boundary moves into the area. Will continue with PROB30 groups to show this potential. Uncertainty with coverage/location and timing is especially high overnight into tomorrow morning. Additional thunderstorms are possible tomorrow afternoon, especially for terminals across the southern portion of the area. Winds through the period will be light from the south overnight, becoming more westerly on Tuesday. Boxell && .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