Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
962 FXUS63 KMKX 131502 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 1002 AM CDT Tue Aug 13 2024 .KEY MESSAGES... - Mostly dry weather expected today with slight chances (< 15%) for showers and a possible thunderstorm across east central Wisconsin and along the lakeshore this afternoon. - Chances for showers and thunderstorms (30 to 80%) from Wednesday night into this weekend. Highest chances (60 to 80%) for rainfall are Thursday / Thursday night. - Strong to severe storms are possible on Thursday. && .UPDATE... Issued 957 AM CDT Tue Aug 13 2024 The forecast remains on track as of mid-morning, with minimal adjustments being made in the 10 AM update. An isolated shower remains possible later this afternoon thanks to a combination of daytime heating, as well as lift along a lake breeze & upper wave approaching from the northwest. The aforementioned disturbance is evident in current water vapor imagery, with extrapolation pointing to the core of the feature passing over north-central and northeastern Wisconsin later today. Given the spacing & likely track of available forcing mechanisms, 10-15% precip probabilities continue over southeastern and east- central Wisconsin, with negligible probabilities remaining further southwest. Afternoon forecast soundings depict ~500-1000 J/kg of MLCAPE in proximity of developing showers, so an isolated clap of thunder can`t be entirely ruled out in any development. Hazards will otherwise be nill in isolated showers/thundershowers this afternoon, with activity quickly tapering following sunset. Quigley && .SHORT TERM... Issued 432 AM CDT Tue Aug 13 2024 Today through Wednesday: Mostly dry weather is expected today as high pressure slowly meanders across the state. There are slight chances for some isolated showers with perhaps a few rumbles of thunder again this afternoon (< 15%) across east central Wisconsin and the along the lakeshore as CAMs indicate development and RAP soundings suggest a few hundred J/kg of CAPE. Any storms that do develop should remain fairly weak owing to weak wind shear. Otherwise, today will feature light winds, partly cloudy skies, and highs in the low 80s. Low pressure will develop across the Central Plains on Wednesday in association with a 500hPa shortwave trough that will eject off the Rocky Mountains. The low will move northeastward towards Wisconsin throughout the day providing increasing cloud cover. Expecting that southern Wisconsin will remain dry as high pressure continues to influence the area with high temperatures in the low 80s. Falkinham && .LONG TERM... Issued 432 AM CDT Tue Aug 13 2024 Wednesday night through Monday: Current models suggest two rounds of showers and storms on Thursday as the aforementioned low moves into the region. The warm front will make its way into southern Wisconsin early Thursday morning with ample dynamics present including WAA, low level moisture, a low level jet, and 850-700 frontogenesis which will allow for the development of the first round of showers and storms. Thinking that the main hazard of this first round of storms will be heavy rain given the expected elevated nature of their development and lack of appreciable instability due to the early morning timing combined with PWATs of 1.5-2 inches. The second round will be associated with the cold front that is expected to move through the area in the evening to overnight hours on Thursday. This second round looks to have a better shot at some strong to severe storms as MUCAPE builds to generally 750-1250 J/kg, mid-level lapse rates steepen to around 7 C/km, and 35-40kt of 0-6 shear will be present as mid to upper level flow increases in magnitude which would support stronger updrafts. The main hazards at this time look to be strong winds and hail. However, the track of the low as well as the environment`s ability to recover from the morning`s convection will largely determine the axis of the strongest storms. A more northerly low track as suggested by the Euro/NAM indicates the potential for strong to severe storms to enter southern Wisconsin while a more southerly track as indicated by the GFS indicates strong to severe storms may remain south of Wisconsin provided we enough clearing occurs during the afternoon. There is good run to run consistency between the individual models, but still differences between the models, so will need to continue to monitor trends. The low will move east of Wisconsin this weekend, but wrap around moisture may result in additional precipitation primarily on Saturday. Dry conditions are expected to start next week as upper level ridging builds over the central United States. Falkinham && .AVIATION... Issued 957 AM CDT Tue Aug 13 2024 VFR conditions currently prevail at all southern Wisconsin terminals. Anticipate that VFR categories will continue through the duration of the period at all fields. A lake breeze, combined with a weak upper disturbance overspreading from the northwest, could encourage the development of a few isolated rain showers over east-central and southeastern Wisconsin this afternoon. Current precip chances (10-15% at MKE, UES, and SBM) are too low to justify any prevailing or PROB30 mentions, though trends will be monitored through this afternoon. Should -SHRA chances increase and/or approach any of the aforementioned aerodromes, amendments will be made. Precip chances will diminish after sunset this evening. Quigley && .MARINE... Issued 432 AM CDT Tue Aug 13 2024 Winds will be light and variable throughout the day as high pressure of 30.1 inches continues to move through the Great Lakes region. An area of low pressure will develop across the Central Plains Wednesday which will move northeast into the Great Lakes region, deepening to around 29.6 inches as it does. Winds will shift to a southeasterly direction Wednesday night in response to the low which will accelerate on Thursday. Waves along the western side of Lake Michigan will build to 6-7 feet at the same time with showers and thunderstorms possible Thursday and Friday. The low will depart the region to the east this weekend, turning winds northwesterly. 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