Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
033 FXUS63 KMKX 041514 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 1014 AM CDT Tue Jun 4 2024 .KEY MESSAGES... - Thunderstorms are expected to develop this afternoon. Isolated severe storms with wind and hail are possible during the afternoon to evening hours. - Additional thunderstorms expected tonight through early Wednesday AM along a cold front. No severe weather is expected from these storms at this time. - Localized heavy rainfall is possible this afternoon through tonight, and may lead to flooding. - Northwest winds bring cooler and drier air to southern Wisconsin for the second half of this week. && .UPDATE... Issued 1010 AM CDT Tue Jun 4 2024 A negative tilt shortwave will gradually lift northeast today and with increasing instability into this afternoon as upper 60 to near 70 degree DPs develop into the region we should expect scattered storm development through the evening. However with little to no shear we expect these storms to largely be of the popcorn style with limited severe risk with the only real risk for hail up to an inch and brief strong gust from collapsing storms. Latest CAMs suggest some storms but mostly weak and not lasting long. As storms dissipate into the mid evening that were associated with the shortwave we will then see the effects of the longwave trough in west central Canada ejecting another wave of energy through the area. This, in addition to the cold front, will be the cause of convection through the afternoon in MN but the remnants of this convection will try to slide through in the late evening and overnight hours. This is expected to be weak if not actively dissipating as it pushes across southern WI. Following the front we will see a brief period of quiet weather before the upper low in Canada with again eject some shortwave energy into the western Great Lakes for Wednesday afternoon and evening. Given some decent midlevel lapse rates behind the cold front we could expect a few storms but nothing severe would be anticipated at this time. Kuroski && .SHORT TERM... Issued 358 AM CDT Tue Jun 4 2024 Today through Wednesday: Dry / quiet weather expected for the remainder of this morning. GOES satellite reveals a shortwave trough currently over northwestern MO. It is expected to drift northeastward, with PVA and diffluent flow aloft leading to ascent in our CWA in the early to mid afternoon hours, likely triggering scattered showers and thunderstorms. Though mostly cloudy skies are forecast ahead of its arrival, the majority of said clouds (aside from a few diurnal cu later in the morning) are thin / high-altitude clouds, allowing a combination of solar heating and southerly surface moist air advection (dewpoints rising from mid 60s to around 70 despite daytime mixing) to rapidly destabilize the atmosphere, achieving 2000 (possibly 3000) joules of SBCAPE, with little to no CIN by this afternoon. With forcing from the approaching shortwave, confidence in convective initiation is high (PoPs increasing to 60% from southwest to northeast this afternoon and evening). With a weakly sheared environment (0-6 km shear 20 kts or less), no supercellular or well organized storms are expected, mostly single cells and clusters capable of a pulse-severe hail and wind threat. Though individual storm cells are not expected to last long, popcorn- style redevelopment and waves of storm clusters (afternoon and evening) will likely lead to off-and-on shower/storm activity for many areas this afternoon and evening. Late this evening into tonight, a cold front sweeps west to east across the region, delivering a 75% precip chance, likely in the form of a north/south-oriented broken line of showers and thunderstorms. With the afternoon and evening pre-frontal convection eating away at the instability, this line of storms is likely to weaken gradually on approach. Some CAMs even show it dissipating before reaching our eastern CWA. The cold front reaches eastern areas and moves out over Lake MI by roughly 7 AM Wednesday morning, with winds shifting westerly and rain chances gradually decreasing behind the front. Showers and weak storms may linger into the Wednesday AM commute, particularly along I-43 north of Milwaukee and I-94 south of Milwaukee (45% chance). Mostly dry and sunny weather expected mid Wednesday, followed by a late afternoon / evening 25% chance of showers and thunderstorms, driven by solar heating and triggered by some diffluence / PVA in the left exit quadrant of an approaching 200mb/300mb jet streak. These storms (if they develop) would be in a strongly sheared low- CAPE environment, and may struggle to organize, unless diurnal destabilization exceeds expectations. Sheppard && .LONG TERM... Issued 358 AM CDT Tue Jun 4 2024 Wednesday night through Monday: Synopsis: Post cold-frontal showers & storms will push east of the region during the overnight hours Wednesday into Thursday. The remainder of the long term period will be characterized by a quasi- steady synoptic pattern featuring longwave ridging over the western CONUS, and mean troughing over the Hudson Bay/Saint Lawrence River vicinity. Tied to the aforementioned upper troughing/ridging, surface low pressure will linger along the Quebec-Ontario border through this weekend, with a broad high pressure ridge remaining stagnant from the foothills of the Rockies into the Plains. West- northwest surface winds will thus prevail through the duration of the long term period, allowing a cooler & drier Canadian air mass to remain in place across the region. Tied to perturbations wrapping around the trough in the Saint Lawrence Valley, isolated rain showers will be possible during the afternoon hours each day. Thursday Through Monday: Cooler high temperatures and significantly lower dew points are forecast with a Canadian air mass becoming established across the state. The overnight update shows highs primarily in the low-mid 70s daily, with dew points generally ranging from the upper 40s to low 50s. Can`t rule out bouts of diurnally-driven shower activity with Wisconsin still proximate to the Saint Lawrence Valley disturbance/shortwaves embedded within it. Rainfall totals are likely to be light in any activity. Quigley && .AVIATION... Issued 1010 AM CDT Tue Jun 4 2024 Mostly high clouds overhead with mostly mid to upper level clouds expected through the evening. We should see some scattered storm development this afternoon and through the evening though only a very small chance (5-10%) for a severe storm in southern WI. Some heavier rainfall at times could reduce VSBYS for brief periods. As the front pushes in late this evening expect some MVFR/IFR CIGS, which should carry through the overnight period and even lingering into Wednesday morning. CIGS could at times fall to LIFR or even VLIFR but will gradually clear from the west into early Wednesday morning. Otherwise expect modest southerly winds today with winds turning to the west behind the front later this evening into tonight. Kuroski && .MARINE... Issued 358 AM CDT Tue Jun 4 2024 A low pressure trough around 29.2 inches will cross the Northern Plains today and move into south central Canada tonight. Southerly winds are expected ahead of the associated cold front. Showers and thunderstorms are expected late this afternoon through tonight. The cold front will cross Lake Michigan Wednesday morning, causing winds to veer westerly. Widespread showers and storms will end by around noon Wednesday. Scattered showers are possible each afternoon through the weekend. Westerly winds continue through the end of the week as low pressure over south central Canada weakens to around 29.4 inches. A Small Craft Advisory is likely for the nearshore zones on Thursday due to gusty west to northwest winds. Sheppard && .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