Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
623 FXUS63 KMKX 252000 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 300 PM CDT Tue Jun 25 2024 .KEY MESSAGES... - Heat index values in the middle to upper 90s are expected until early evening across portions of the area. - Strong to severe storms should remain to the south of the area later into tonight, with strong thunderstorms possibly returning later on Friday into Friday night. - River flooding and high water levels will continue this week and into this weekend. && .SHORT TERM... Issued 300 PM CDT Tue Jun 25 2024 Tonight through Wednesday night: The main cold front is still working its way southeast through the area. Very warm and humid conditions will continue ahead of it, with dew points in the 70s and heat index values into the middle to upper 90s in some areas. CAMs continue to suggest that the front should be southeast of the area by early this evening. They develop new strong to severe convection along the front in northern or central Illinois by later this afternoon, within a very unstable airmass with 35 to 40 knots or more of 0 to 6 km bulk shear. CAMs have been consistent with the strong to severe convection remaining south of the area, though the latest HRRR has convection developing just south of the Illinois border by 00Z Wednesday. Forecast soundings still show a cap with the warm temperatures in the low levels, so that may hinder development with the lack of any other forcing mechanisms. Thus, will maintain low PoPs near the Illinois border into tonight. Will watch the far southern portions of the area for any signs of convection. Dew points may remain high enough overnight into Wednesday morning with the light winds to have some fog, possibly dense, move onshore from Lake Michigan. Will continue to watch for this potential and adjust the forecast near the lake if needed. High clouds from convection to the south may linger tonight, before scattering out on Wednesday. A passing shortwave trough may bring more clouds, along with a few showers, with lingering low level instability. For now, kept forecast dry but may need to add in some PoPs in later forecasts. It looks to be a less humid day but still mild. Winds may shift onshore near the lake in the afternoon, bringing cooler temperatures there. High pressure should move into the region Wednesday night, bringing quiet weather and cooler temperatures. Wood && .LONG TERM... Issued 300 PM CDT Tue Jun 25 2024 Thursday through Tuesday: High pressure should continue to bring pleasant summer weather to the area for Thursday into Thursday night. Warm air advection will develop later Thursday night into Friday, as a southwesterly low level jet develops and transports more moisture into the region. A cold front should pass eastward through the region sometime Friday night or Saturday morning. The main 500 mb shortwave trough misses the area to the north, but there will be low level frontogenesis with the front to help bring chances for showers and thunderstorms. Any strong to severe potential will be tied to the timing of the front and if the low level jet can sustain elevated convection. This will be the next period to watch for potential strong to severe storms, though forecast soundings are showing mainly elevated CAPE with modest bulk shear of 20 to 25 knots. This could lead to multicell development with some heavy rain potential as well, with precipitable water values approaching or reaching 2.00 inches. Strong cold air advection with high pressure should bring cooler and less humid air into the region later Saturday, with quiet weather into Sunday. This trend is generally supported by ensembles. Ensembles then show more potential for showers and thunderstorms early next week, as more warm air advection and moisture moves into the region. Thus, the active weather pattern continues. Wood && .AVIATION... Issued 300 PM CDT Tue Jun 25 2024 May see some sprinkles move through the area into early this evening, with middle level clouds. Gusty west winds will weaken somewhat and become northwest into early this evening, as a cold front moves through and to the southeast of the area. Ceilings should gradually scatter out or rise above 3000 feet AGL during this time. Any thunderstorm development with the cold front should remain south and southeast of the area into tonight. Light northwest winds tonight will become north to northwest on Wednesday. May see patchy fog, some dense, move onshore from the lake overnight into Wednesday morning, but confidence is too low to mention in TAFs. May see northeast winds for terminals near Lake Michigan by Wednesday afternoon. High clouds from thunderstorms to the south may cover the area tonight into early Wednesday morning, before scattering out in the afternoon. May see some light rain showers move through Wednesday afternoon. Wood && .MARINE... Issued 300 PM CDT Tue Jun 25 2024 Gusty southwest winds will become lighter and veer to the west and northwest this evening, as a cold front moves across the lake. There are chances for showers and thunderstorms into tonight across far southern portions of the lake, as the cold front pushes through. Winds will shift to the north later tonight into Wednesday, becoming gusty at times. Lighter winds return later Wednesday night into Thursday night, as high pressure around 30.0 inches shifts across the region. Increasing south winds are then forecast for Friday, becoming southwest to west on Saturday, as a cold front moves through the region. Chances for showers and thunderstorms increase during this period. Wood && .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