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Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
438 FXUS63 KMKX 032020 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 320 PM CDT Wed Jul 3 2024 .KEY MESSAGES... - Independence Day Afternoon: Isolated to scattered showers and thunderstorms are expected during the afternoon. Best chances for showers and thunder in central and southwestern Wisconsin (25 to 45 percent chance). A few later afternoon storms could produce gusty winds. - Independence Day Evening: Areas along and west of I-39 have the greatest chances (50-80%) to see showers/storms between 5 PM CDT and 11 PM CDT, while areas east of I-39 have lower (15-45%) potential. Early evening storms could produce gusty winds and small hail. - The greatest window for showers and thunderstorm chances (>65%) will be after 10 PM CDT tonight through Friday with medium (45-65%) potential for rainfall to exceed one inch northwest of HWY-151. Widespread accumulations up to 0.25 inch are expected. - 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 321 PM CDT Wed Jul 3 2024 Tonight through Thursday night: Mostly sunny skies and light westerly winds continue through this evening, with winds becoming light and variable overnight. Low temperatures in the mid-60s are expected. A few areas of patchy fog are possible in the low lying areas of southwestern Wisconsin as moist soils remain after recent rainfall. Currently expecting drier air in the remainder of the boundary layer to prevent widespread fog production. Temperatures increase quickly under a mostly clear sky and light southerly winds Thursday morning (Independence Day), with highs in the low to mid-80s expected. A lake breeze is expected to develop in the midday hours and reduce temperatures in lakeshore counties through the afternoon. During the afternoon hours, MUCAPE upwards of 1000 J/kg and a few shortwave ripples ahead of a deepening upper low may assist with scattered shower and thunderstorm development. Generally expecting these showers and thunderstorms to be short-lived as pop-up variety thunderstorms due to a lack of environmental shear. However, a few storms may grow enough to produce gusty winds or small hail after 4 PM CDT. Lake breeze component looks to keep those areas stable without pop-up thunderstorm potential during the afternoon and evening hours. A frontal boundary looks to begin to push eastward through southwestern Wisconsin around 7 PM CDT, although there remain differences in timing by a few hours on CAMs. These storms move eastward through the I-39 corridor by 11 PM CDT, and into southeastern Wisconsin thereafter. Concerns remain for gusty wind and small hail through the evening hours, diminishing overnight. However, thunderstorms continue throughout the overnight hours, with a reinforcing cold front during the late overnight hours bringing additional storm chances. Storms continue through the overnight hours as low pressure deepens and propagates eastward. Storms look to remain progressive and not tap into the full potential of PWATs around 1.5 inch, but potential remains (45 to 65 percent) for greater than an inch of precipitation north and west of HWY-151. Localized river flooding is expected to continue. MH && .LONG TERM... Issued 321 PM CDT Wed Jul 3 2024 Friday through Wednesday: Showers and thunderstorms continue through much of Friday on the back side of departing low pressure. Generally expecting precipitation rates to be lower with this activity, with accumulations less than a half inch expected. Still, river flooding concerns continue into the weekend. Northwesterly breezes and overcast skies will keep temperatures in the 70s. Dry and clear conditions Saturday will bring temperatures back to near 80 degrees, with light northwesterly winds as high pressure builds back into the central Plains. A 500 mb trough is then expected to affect the Upper Midwest Sunday into Monday, bringing additional thunderstorm chances. As the trough departs on Tuesday, additional showers and thunderstorms are possible as southern Wisconsin remains on the northern edge of the central Plains ridging. Due to uncertainty of convective evolution, kept NBM PoPs through the long term. Seasonable temperatures near 80 degrees remain through Wednesday. MH && .AVIATION... Issued 321 PM CDT Wed Jul 3 2024 A few diurnal cumulus around 5000 ft have developed across southern Wisconsin, with VFR conditions expected to continue throughout the overnight hours. Patchy fog may develop in low- lying areas of southwestern Wisconsin overnight, including JVL, although confidence remains low (20 percent) in widespread fog potential. Light southwesterly winds this evening will become light and variable overnight, before becoming southerly into Thursday afternoon. A few pop-up thunderstorms are expected Thursday afternoon from KUES westward, with more widespread thunderstorms expected Thursday evening into the overnight as a front pushes eastward through the area. MH && .MARINE... Issued 321 PM CDT Wed Jul 3 2024 Breezy south winds across Lake Michigan this afternoon will diminish and become westerly overnight as weak high pressure moves east across the lower Great Lakes region. Light westerly winds will be in place to start the day on Thursday, but are expected to turn easterly and accelerate by Thursday afternoon as low pressure deepens over Wisconsin Thursday night into Friday. As the low pressure system moves across Wisconsin on Friday, winds across the southern half of the lake will generally be from a south to southwesterly direction whereas winds across the northern half of the lake will be from an east to northeasterly direction. Gusts across the lake will be around 20 kt on Friday. Showers and thunderstorms are also possible across the lake on Friday associated with the low. As the low moves across central Lake Michigan Friday night, winds will become more variable, but will become northwesterly for the start of the weekend as the low lifts northeastward into eastern Canada. Falkinham && .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