Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
849 FXUS63 KMKX 181610 AAA AFDMKX Area Forecast Discussion...UPDATED National Weather Service Milwaukee/Sullivan WI 1110 AM CDT Tue Jun 18 2024 .KEY MESSAGES... - Small chances (15 to 20 percent) for showers and storms in southern and southeastern parts of the area this afternoon. - Chances (30 to 40 percent) for showers and storms overnight into Wednesday night. - Heat index values will be between 95 and 100 degrees this afternoon. Hydration and frequent breaks are advised if working outdoors. - Dangerous swim conditions are likely into tonight at Lake Michigan beaches in Sheboygan and Ozaukee Counties. && .UPDATE... Issued 1110 AM CDT Tue Jun 18 2024 Any lingering light showers or sprinkles will move out of far southeast Wisconsin, as a shortwave trough shifts out. Low clouds are lingering across parts of the area, and may linger for several more hours before scattering out by middle afternoon. Confidence is low in how long it may take to mix out these low clouds, which would affect high temperatures and subsequent instability. If they linger through the afternoon, high temperatures and instability will be reduced. Kept highs in the 90 to 92 degree range for the most part, but may need to adjust down if the low clouds persist. Heat index values in the middle to upper 90s are expected if the forecast highs are reached. Onshore winds from Port Washington north into Sheboygan will keep those areas cooler. Forecast high temperatures will be close to convective temperatures, especially in southern and southeastern parts of the area. If these highs do occur, then widely scattered pop-up showers and storms are possible to occur. 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. There are better chances for showers and storms (30 to 40 percent) overnight into Wednesday night, as a cold front sags southeast into the area and washes out. Generally weakening showers and storms from the west overnight may shift into the western parts of the area. This may linger into Wednesday morning. 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 and downbursts to occur. This will be conditional on clouds scattering out and enough instability developing. Wood && .SHORT TERM... Issued 459 AM CDT Tue Jun 18 2024 Today through Wednesday: This morning, a week wave over the southern end of Lake Michigan is expected to bring some low clouds to southeastern WI, along with slight chances for rain (~15%). Any rain that happens is expected to be widely scattered. Skies should clear mid morning and the heat should build, with highs in the low 90s, amid dew points in the low 70s. Resulting heat indices will be between 95 and 100 this afternoon. In addition to the heat, southerly winds will gust between 25 and 30 mph. At local beaches in Sheboygan and Ozaukee counties, this will drive a High Swim Risk from high waves and dangerous rip currents this morning into tonight. A Moderate Swim Risk will exist in Milwaukee and Racine Counties. Even with the high heat outside, swimming is not advised. Overnight, the large ridge over the eastern United States will lean more latitudinally, allowing for a cold front to make an approach at Wisconsin from the northwest before washing out. This cold front will drag showers and storms over central WI overnight. Through the day on Wednesday, the cold front will become more of a southwest to northeast oriented stationary front from Iowa into lower Michigan. Convergence along this baroclinic zone will drive on and off scattered shower and storm chances through Wednesday into Thursday. Heat will still linger south of the baroclinic zone on Wednesday, and much of southern WI will see highs in the upper 80s to low 90s again. CMiller && .LONG TERM... Issued 448 AM CDT Tue Jun 18 2024 Wednesday night through Monday: Lee troughing over the front range of the Colorado Rockies will allow for an increase in southerly flow over the plains Wednesday night into Thursday morning. Sfc WAA will allow moisture to surge back north and the stationary front should lift north as a warm front. Through the day on Thursday, sfc flow along the sfc trough/warm front will allow for east flow off of the lake, driving a lake modified air mass inland. As a result, much of southern WI should see a break from the heat, although conditions will still remain humid with dewpoints remaining in the mid to upper 60s. Weak scattered shower and storm activity may occur along the warm front as well. The WAA will bring another surge of warmth north for Friday and Saturday with daytime highs on both days in the upper 80s. Relief may not finally come until a cold front comes through Saturday night. The NBM paints great PoPs at 70%, suggesting a line of showers and storms along with the front Saturday night. Temperatures then cool for Sunday and Monday. CMiller && .AVIATION... Issued 1110 AM CDT Tue Jun 18 2024 Low clouds with ceilings of 1800 to 2500 feet AGL continue to linger across the area, and may linger into or through the afternoon hours. Uncertainty exists with how long it may take to get these low clouds to scatter out. South winds will continue to be gusty this afternoon, before weakening somewhat tonight. There may be low level wind shear conditions tonight, with southwest winds around 2000 feet AGL of 40 to 45 knots. A few showers and storms may pop up this afternoon and early evening. Weakening showers and storms should move into areas west of Madison overnight and may spread over the area into Wednesday morning. Low clouds with ceilings of 1500 to 2500 feet AGL may spread over the area during this time, and may linger into the rest of Wednesday and into Wednesday night. There may be more showers and storms that form along a weakening and stalling cold front Wednesday afternoon and evening, but uncertain how much of this activity will occur at this time. Wood && .MARINE... Issued 1110 AM CDT Tue Jun 18 2024 Low pressure around 29.5 inches will move from the northern Plains into northwestern Ontario today. Gusty south winds are expected today and tonight. A Small Craft Advisory is in effect through this evening for the nearshore waters, with the gusty winds and building waves. Gusts over the open waters may reach 30 knots at times this afternoon 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 then gradually ease early Wednesday morning, and lighter southwesterly winds are then expected through Wednesday, as the low continues to move into Hudson Bay. A cold front will slowly push southward across the lake Wednesday night into Thursday, shifting winds to the northeast. 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