Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
064 FXUS63 KMKX 150152 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 852 PM CDT Tue May 14 2024 .KEY MESSAGES... - Decreasing clouds overnight. Dry conditions Wednesday. - Next round of showers and storms expected to impact southern Wisconsin on Thursday, with additional rounds into this weekend. && .UPDATE... Issued 850 PM CDT Tue May 14 2024 A gradual decrease in cloud cover is expected to continue from northwest to southeast overnight tonight as low pressure drifts eastward across Kentucky. The southeastern half of the CWA may hold on to some of its mid and upper altitude clouds into the early morning hours of Wednesday, hence the coolest overnight low temps in our forecast (low 40s) are found in the north CWA where it is already clear. Still expecting dry wx on Wednesday, with a continued northeast breeze keeping Lake Michigan counties much cooler than their inland counterparts. Sheppard && .SHORT TERM... Issued 255 PM CDT Tue May 14 2024 Tonight through Wednesday night: Weak 925-850mb frontogenesis and plenty of moisture in the 850-700mb level, along with deformation in the upper levels, are responsible for the lingering clouds and light showers/drizzle. Weak low pressure slowly moving across southern WI this afternoon will make its way to the Ohio River Valley while weakening tonight through Wednesday. With the slower movement of this system, the clouds are much slower to clear across southern WI this afternoon. In fact, mid level clouds may linger across southeast WI until mid Wednesday morning due to the lack of any advection of dry air. Once the clouds do clear from northwest to southeast late tonight to mid Wednesday morning, temps will increase into the lower 70s for inland areas. The onshore winds will keep lakeshore areas cooler, but warmer than today, with highs in the 60s. Cronce && .LONG TERM... Issued 255 PM CDT Tue May 14 2024 Thursday through Tuesday: A surface low pressure center will propagate into northwestern Wisconsin Thursday morning supported by a weakening 500hPa shortwave trough before moving off into Lake Superior by Thursday night. Forcing via the associated occluded front is expected to move eastward across the state throughout the day which combined with the upper trough and low level moisture advection will bring precipitation chances to southern Wisconsin (60%-70%). MUCAPE of 500-1000 J/kg and ~30kt 0-6km bulk shear suggests thunderstorm development along the boundary is possible with a generally discrete storm mode currently expected given 0-6km shear is roughly perpendicular to the front. Model soundings also depict a saturated column with PWATs of ~1.25 inches and mid-level lapse rates of ~6.5 C/km which suggest that showers and storms that develop will likely be efficient rain producers. Decreasing clouds and drier conditions are expected on Friday, but with another weak shortwave trough and PVA running across the state combined with a well-mixed boundary layer, there may be showers and perhaps a few rumbles of thunder across southern Wisconsin in the afternoon (20%-30%). A lot of uncertainty surrounds the forecast this weekend. Models are starting to come into better agreement surrounding a 500hPa shortwave trough and surface low traversing the northern Great Plains Friday night into Saturday before entering the Great Lakes region on Saturday night. Amplitude and timing of this trough are still things to monitor with coming model runs, but it is noteworthy that the long range deterministic guidance now depicts this 500hPa trough as compared to a few runs ago where there was discrepancy between if zonal or meridional flow was dominant aloft. Have stuck with NBM guidance for the weekend due to this uncertainty. However, upper level ridging and surface high pressure appear to build across Wisconsin on Monday before precipitation chances return again on Tuesday. Falkinham && .AVIATION... Issued 850 PM CDT Tue May 14 2024 Though scattered to broken clouds currently linger in far southeastern WI, cigs are already at VFR altitude, and should remain so as cloud coverage continues to decrease overnight. Dry weather and VFR continue through Wednesday evening, with mostly clear skies. A northeast breeze is expected to continue in Lakeshore counties, with slower due east winds for inland areas on Wednesday. Sheppard && .MARINE... Issued 255 PM CDT Tue May 14 2024 Low pressure over southern IL will continue to weaken overnight as it tracks along the Ohio River Valley. Northerly winds up to 30 kt over Lake Michigan will diminish overnight, but remain northerly into Wednesday evening. Southerly winds will develop Thursday as a weak low pressure trough tracks into western WI Thursday afternoon. Scattered showers and thunderstorms are expected along the trough. Winds will become variable behind the trough passage Friday as weak high pressure builds over the Upper Great Lakes. The pattern remains unsettled for the weekend with chances for showers and thunderstorms, but no periods of elevated winds are anticipated. Cronce && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 4 AM Wednesday. && $$ 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