Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
672 FXUS63 KMKX 180129 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 829 PM CDT Tue Sep 17 2024 .KEY MESSAGES... - Summer-like warmth continues through the remainder of the week. Daytime highs will range between five and fifteen degrees above normal. - Dry conditions prevail through Thursday, then a cold front brings showers and storm potential Thursday night and Friday. On and off chances for showers and storms are then expected Saturday into Monday. && .UPDATE... Issued 829 PM CDT Tue Sep 17 2024 Srn WI will remain on the wrn periphery of high pressure over New England while a narrow upper ridge continues. Above normal temps and mostly clear skies will continue into Wed. Gehring && .SHORT TERM... Issued 238 PM CDT Tue Sep 17 2024 Tonight through Wednesday night: Dry and hot conditions continue through today and Wednesday with high temperatures in the mid to upper 80s away from the immediate lakeshore. Low dewpoints will lead to relative humidity values falling into the 25 to 30 percent range both today and Wednesday away from Lake Michigan. A few spots in southwestern Wisconsin may dip below 25 percent at times. A lake breeze will keep temperatures and humidity values temperate in the afternoon hours in Lake Michigan counties both days. Relief from the heat is expected during the overnight hours tonight and again Wednesday as low dewpoints continue and a lack of cloud cover allow temperatures to fall into the mid-50s. High pressure dominates to the east, while semi-permanent low pressure lingers in the northern High Plains. This will yield light southeasterly winds through Wednesday, except for nearly calm winds during the overnight hours. Areas along the Kettle Moraine and low-lying river valleys are expected to see patchy ground fog development once again. MH && .LONG TERM... Issued 238 PM CDT Tue Sep 17 2024 Thursday through Tuesday: Blocking pattern begins to erode with an upper-level cutoff low pivoting into the Desert Southwest on Thursday, with a jet streak riding over the Great Plains Ridge and assisting with frontogenesis across the Upper Midwest. This frontal development will progress eastward slowly Thursday evening into Friday, but the overall pattern looks to pull the surface low northward, limiting the cooling and moistening effects of this front. Still, showers and thunderstorms are possible Thursday night into Friday along this frontal boundary, especially in southwestern Wisconsin. Meanwhile, an additional upper level trough feature pushes into western Canada, with interplay between this trough and the Desert Southwest cutoff setting the stage for precipitation this weekend into early next week. Surface high pressure is expected to slowly shift northward between developing low pressure in the lee of the Rockies and a developing low in the Atlantic. Phasing between the Canadian and Southwestern troughs will dictate the strength of the western low pressure system and therefore when and how much precipitation southern Wisconsin will see Sunday through early next week. Confidence remains low, with models diverging widely as per placement and timing of troughing, so generally kept NBM PoPs through the weekend into early next week (20 to 40 percent chance). Regardless of exact timing of precipitation and associated cloud cover, less impressive ridging going into early next week should allow temperatures to fall back to near average in the mid to upper 70s. MH && .AVIATION... Issued 829 PM CDT Tue Sep 17 2024 Other than patchy ground fog over ern WI during early Wed AM, VFR conditions will prevail tnt-Wed nt. Gehring && .MARINE... Issued 238 PM CDT Tue Sep 17 2024 High pressure around 30.2 inches over the Northeast and low pressure around 29.3 inches the northern High Plains will keep winds light through Wednesday. High pressure will gradually weaken and drift eastward on Thursday, with the low strengthening to 29.2 inches. This will produce south-southeast winds Thursday into Friday. In addition, a weak front will push southeastward across the open waters Thursday night into Friday, bringing showers and isolated thunderstorms. Low pressure will slowly shift eastward toward the Great Lakes region this weekend, with winds remaining generally southeasterly. As low pressure approaches, additional showers and thunderstorm chances develop, especially across the southern half of the Lake. MH && .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