Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
214 FXUS63 KMKX 041955 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 255 PM CDT Thu Jul 4 2024 .KEY MESSAGES... - This Afternoon and tnt: Scattered showers and storms (30-50% chances) are expected to develop this afternoon across srn WI. Severe wx is not expected with these storms. A line of storms will then move from west to east across srn WI this evening. Damaging winds would be the main threat for south central WI with the storms gradually weakening as they move toward ern WI late in the evening. - Rainfall tnt through Friday: Expect widespread totals around a quarter to half and inch, but areas northwest of HWY-151 have a 50-80% chance for totals to exceed one inch. - Elevated water levels continue on area rivers and streams through the end of the week. Flood Warnings remain in effect in several locations. && .SHORT TERM... Issued 255 PM CDT Thu Jul 4 2024 Tonight through Friday night: Scattered slow moving thunderstorms have developed along a weak warm front west of Madison, while isolated showers and storms are developing over se WI. MLCAPE ranges from 500-1000 J/KG this afternoon with a vorticity maximum moving across srn WI. SVR storms are not anticipated with this activity but urban and small stream flooding will be possible mainly west to nw of Madison. For tnt the upper low currently over the ern Dakotas will track to west central WI by 12Z Fri with its sfc low around 1006 MB in the same vicinity. A line of strong storms is ongoing near the sfc low and cold front from south central MN into north central IA. The HREF has a reasonable scenario of bringing a line of strong storms from sw WI into south central WI this evening then with gradual weakening as CAPE declines. Overall, this is supported by a 500 mb wswly 50 kt jet nosing into srn WI ahead and within the deep convection; thereby increasing deep layer shear to at least 50 kts. This gives some confidence for MCS development as the HREF supports, but the strong shear also makes the timing of weakening difficult since the MCS could maintain its strength longer than what would be typical. The cold front will then gradually move across srn WI late tnt through Fri AM as the sfc low and upper wave move across central WI. The persistent showers and scattered storms will be toward central WI where the better warm, moist advection and PVA is located; however, the upper trough axis will support 50-70 percent chances of rain for the remainder of srn WI. The upper trough and moisture will then linger into the evening thus expecting sct showers to linger. The areas that could see widespread 1 inch rainfall amounts with locally 2 inch amounts would be north and west of Madison especially with the MCS this evening. Urban and small stream flooding may occur given the saturated soils. Gehring && .LONG TERM... Issued 255 PM CDT Thu Jul 4 2024 Saturday through Thursday: A brief period of high pressure and shortwave ridging aloft will take hold for Sat. Afterward, a series of shortwave troughs will support mean upper troughing over the Upper MS River Valley and wrn Great Lakes. Thus chances for showers and storms will be forecast each day. Temps during the extended will be near normal with above normal relative humidity. Gehring && .AVIATION... Issued 255 PM CDT Thu Jul 4 2024 VFR conditions will prevail this afternoon and evening but areas of MVFR Cigs and vsbys may occur following thunderstorms. Widespread stratus development with Cigs of 600-1900 feet are then expected to develop from west to east early Fri AM through late Fri AM with the passage of low pressure and a cold front. Intermittent showers and isold storms will continue during this time, while Cigs will rise to 1-3 kft for Fri afternoon. Gehring && .MARINE... Issued 255 PM CDT Thu Jul 4 2024 Weak high pressure around 29.9 inches over Lake MI this afternoon will slide eastward this afternoon and evening, as a couple weak low pressure areas develop east across MN and from IL into IN during the afternoon and early evening. Light and variable winds are expected over Lake MI. More organized south to southeast winds will develop over the south half tonight into Friday morning, with east northeasterly winds over the north half as low pressure around 29.7 inches moves from MN across central WI. This low pressure area will gradually track eastward across the middle of Lake Michigan early Friday afternoon. Modest southwest winds will prevail over central and southern Lake MI at this time with northeasterly winds to the north. The winds will then trend to north northwest Friday night into Saturday morning as the low moves away across Lake Huron and southern Ontario. The winds will then back to southwest during the afternoon and evening, and southerly for Sunday as high pressure around 30.0 inches moves across Lake MI and tracks to the lower Great Lakes. Gehring && .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