Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
288 FXUS63 KMKX 030938 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 438 AM CDT Wed Jul 3 2024 .KEY MESSAGES... - Drier and much warmer today with temps in the mid to upper 80s. Warmer temps will continue into Independence Day. - Independence Day Morning: Looks to mostly be dry into the early part of the afternoon across much of southern WI. - Independence Day Afternoon: Spotty showers and few rumbles of thunder will be possible late afternoon into the early evening across southern WI, but if anything develops they would be brief and most areas may remain dry. - Independence Day Evening: Showers and thunderstorm chances increase through the evening. Areas west of I-39 have the greater chances (40- 80%) to see showers/storms between 5pm-11pm while areas east of I-39 have lower (10-40%) potential. - The greatest window for showers and thunderstorm chances (>60%) will be overnight, generally after 10pm-1am through Friday with medium (40-60%) potential for rainfall to exceed one inch, mainly northwest of HWY-151. - 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 434 AM CDT Wed Jul 3 2024 Today through Thursday: Some scattered showers will linger along with the cloud cover through the early morning hours before we clear out by mid- morning. Expecting mostly dry conditions today with precip chances next to nothing, but given PWATs look to be greater than 1 inch, a small swath of lingering mid-level vorticity, and temps near the convective temps, cannot rule out seeing some patchy showers develop this afternoon. However, think the the dry air and subsidence from incoming surface high will win out and keep things dry this afternoon. Otherwise expect weak westerly winds and plenty of sunshine through the afternoon as a broad area of high pressure builds across the region through the evening. Thus temps look to climb into the mid to upper 80s this afternoon. While potential remains low (<20%), it would not be out of the realm of possibility to see a few locations in southeast WI creep toward or even exceed 90F this afternoon. All eyes are on the Independence Day forecast. Models continue to follow the dry trend for the morning into the early afternoon as the surface high pressure slides east. However, shower and thunderstorm chances pick up through the second half of the day. For the afternoon, there remains the potential for a few brief, spotty showers and thunderstorms to develop as an impulse of mid-level vorticity (dCVA) pushes across the area ahead of the main upper- level trough. Pair the mid-level forcing with low- level WAA and an effective warm front lifting across southern WI with SBCAPE building to around 500-1000 J/kg and this may be enough to support the scattered thunderstorm development. Main window looks to be 4pm and sunset and lightning will be the primary concern for this round as thunderstorms look to be of the pulse-type nature. Although the environment does not favor the upscale growth given the lack of shear and lower-lapse rates paired with the upper-level dynamics remaining upstream, still cannot rule out seeing a stronger storm or two capable of producing strong gusts and maybe even some small hail if development is driven by mesoscale features, such as a nearby outflow. Overall chances remain lower at this time, but bears watching given the holiday and increased outdoor festivities. Wagner && .LONG TERM... Issued 434 AM CDT Wed Jul 3 2024 Thursday night through Tuesday: The better shower and thunderstorm chances along with more widespread shower coverage will be overnight Thursday into Friday as the upper-level trough pushes into the Upper Mississippi River Valley. The associated surface low will follow a similar track and is progged to deepen to sub 1008 mb level as it tracks over southern WI. Along with the more favorable dynamics and forcing, we will see moisture advection bring PWATs greater than 1.5 inches with this system. Given the slow moving nature of the low as it occludes and persistent moisture transport, expect widespread rainfall beginning generally after 03z and persisting into much of the day Friday. There will be periods of moderate to heavy rainfall, but QPF generally looks to remain below an inch for this activity. However, any deeper convection that may develop and train over the same area would be capable of producing localized heavier rainfall exceeding and inch or two through Friday morning. By the second half of the day Friday we begin to see the system lift east-northeast and lose the better forcing, but lighter showers will likely linger through much of the afternoon and into Friday evening. Saturday is looking drier as mid-level ridging sets up over the region and surface high pressure tracks south of the area. Then an active pattern returns for the later half of the weekend into early next week as a series of shortwave troughs traverse the region. Each passing wave will bring a bout of showers and thunderstorms. Wagner && .AVIATION... Issued 434 AM CDT Wed Jul 3 2024 A cold front is pushing through this morning with some lingering light showers/drizzle and lower ceilings/visibility. This activity is responsible for the lower flight conditions where widespread ceilings below 1000 ft persist across southern WI. However, expecting the cold front to push east and ceilings/visibility to improve through the morning as high pressure builds in through the day. Then mainly expecting VFR conditions today with light westerly winds. VFR conditions are expected to prevail through this evening and into Thursday morning with light and variable winds. Wagner && .MARINE... Issued 434 AM CDT Wed Jul 3 2024 Low pressure across far northwestern Ontario will drag a weak cold front across Lake Michigan through the morning. Winds will turn more west-southwest behind it and pick up through the afternoon with gusts to around 20-25 knots. Then a weak area of high pressure over the Central Plains this morning will gradually slide into the area this evening easing the west- southwesterly winds this evening into the start of Thursday/Independence Day. Winds will gradually increase through the evening as low pressure treks across the Upper Mississippi River Valley and deepens over WI overnight into Friday. Expect northeast-east winds across the northern half of the lake and more west-southwest winds across southern portions as the low pressure system tracks across the middle section of Lake Michigan Friday evening/night. As low pressure lifts into eastern Ontario/Quebec Saturday, expect more northwesterly winds behind it to gradually weaken through Saturday evening. Wagner && .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