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Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
439 FXUS63 KMKX 120911 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 411 AM CDT Mon Aug 12 2024 .KEY MESSAGES... - Low chances (15 to 20%) of showers and possibly a thunderstorm across east central WI this afternoon. - Dry conditions are expected Tuesday and Wednesday as high pressure influences the region. - Chances for showers and thunderstorms (30 to 70%) from Wednesday night into this weekend. Highest chances (60 to 70%) for rainfall are Thursday / Thursday night. && .SHORT TERM... Issued 406 AM CDT Mon Aug 12 2024 Today through Tuesday: A weak upper shortwave trough currently over Iowa as seen in water vapor imagery and associated shower/thunderstorm development is expected to stay to our southwest and south as they move through the region. However, upper level cloudiness is expected to continue streaming across southern Wisconsin as these features propagate eastward. Otherwise, dry conditions are expected across southern Wisconsin through much of the day. At 500hPa, Wisconsin is sandwiched between an area of low pressure across the northeastern United States and the ridge building across the central United States. Jet streaks associated with these features remain to our east and south as seen in the observed upper air analysis which will put northern and east central Wisconsin in an area of speed divergence and lower heights aloft come this afternoon. A lake breeze is also expected to develop this afternoon under partly cloudy skies which will promote surface convergence along the lakeshore. As such, there is a chance (15-20%) for shower development this afternoon across east central Wisconsin. Expecting anything that develops to primarily be showers, but can`t rule out a rumble of thunder given a few hundred J/kg of CAPE as seen in model soundings and convective cloud depths reaching above -10C. High temps today will be in the upper 70s, with a few locations potentially breaking 80F. Upper level ridging then builds back into the area Tuesday with dry air throughout the column. Deterministic global models suggest additional precipitation development on Tuesday, mainly along the Lake Michigan shoreline, but currently thinking that ample subsidence associated with the upper ridge and surface high pressure combined with the dry air will not be conducive to said development and have kept the forecast dry on Tuesday. Falkinham && .LONG TERM... Issued 406 AM CDT Mon Aug 12 2024 Tuesday night through Sunday: Dry conditions are expected to remain Tuesday night through Wedensday as the upper ridge and surface high pressure continue to dominate the Midwest region. A 500hPa trough ejects off the Rockies Wednesday afternoon, supporting the development of a surface low pressure center across the Great Plains which will lift northeastward and move through the Midwest Thursday and Friday. Showers and thunderstorms are expected to develop in association with this feature as WAA, 850-700 frontogenesis, and the nose of a low level jet move towards southern Wisconsin. Models appear to be in better agreement as far as timing goes, so chances have been bumped up slightly (60 to 70%) for showers and storms Thursday morning, although the location of heaviest rainfall is a challenge. The low will move through Wisconsin on Friday, but moisture on the backside of the low provides additional precipitation chances through the weekend. Falkinham && .AVIATION... Issued 406 AM CDT Mon Aug 12 2024 VFR conditions are expected throughout the TAF period. Mid to high clouds will continue streaming across southern Wisconsin this morning as ongoing showers and storms across Iowa move eastward. Diurnal cumulus around 5kft is expected to develop this afternoon with light winds out of the west. A lake breeze is also expected this afternoon which will shift winds at the lakeshore sites to an easterly direction. There is a 15-20% chance of showers across east central Wisconsin this afternoon with SBM being the most likely to see any precipitation, but can`t rule out a rumble of thunder. Otherwise the forecast remains dry today. Falkinham && .MARINE... Issued 406 AM CDT Mon Aug 12 2024 High pressure of 30.1 inches centered over Illinois this morning will continue to move eastward Monday and Tuesday allowing for lighter and more variable winds. Winds will become east to southeasterly and accelerate on Wednesday as low pressure of 29.7 inches develops across the Central Plains and moves towards lifts northeast towards the Great Lakes, moving through the region on Thursday and Friday. Shower and thunderstorm chances exist across Lake Michigan on Thursday and Friday due to this low. 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