979 FXUS63 KMKX 041349 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 849 AM CDT Sun Apr 4 2021 .UPDATE... (Issued 848 AM CDT Sun Apr 4 2021) Expect some increase in mid-high level clouds today as mid-level warm air advection moves across Wisconsin, with the main push across the north. Inland high temperatures getting into the low 70s still looks good with breezes off cool Lake Michigan keeping shore areas considerably cooler. Kavinsky && .SHORT TERM... (Issued 425 AM CDT Sun Apr 4 2021) Today through Monday Night: Today, a low pressure system/surface trough feature will gradually lift NE- ward into the arrowhead region of Minnesota. As it does, a warm front will lift northeastward during the afternoon hours. Mostly southerly winds away from the lakeshore will support highs in the low to mid 70s. Areas along a line from Kenosha to roughly west of Fond du Lac and eastward will see cooler high temperatures today, as southeasterly winds will create a fetch off of the lake. There will be passing high clouds today as well, owing to the low and overrunning along the warm front. It'll be dry again today, and mixing will once again support a bottoming out of RH values. A full fire weather discussion can be found below. Overnight Sunday into Monday, we'll get into the warm sector of the low pressure system and dew points will gradually rise. Aloft, some 850mb warm advection will steepen lapse rates and support a few hundred Joules of elevated CAPE. With the warm front present as the initiating boundary, some sparse shower and thunderstorm activity could develop before daybreak. Shower and Thunderstorm activity may then increase in coverage over southern WI during the morning and early afternoon hours as a subtle 500mb vortmax moves overhead, providing some more upper- level support. Activity will then die off during the late afternoon as the vortmax shifts eastward. Fire weather concerns will likely come to an end on Monday as min RH values are expected to be around 50% and the scattered shower activity will impart some much needed moisture to dry plants. CMiller && .LONG TERM... (Issued 425 AM CDT Sun Apr 4 2021) Tuesday through Saturday: The sfc trough over central WI will stall and weaken on Tue but will hang onto slight chances of showers/tstorms for now. Cyclogenesis will continue over the central Great Plains in response to an upper low crossing the central Rockies. Warm conditions are expected once again on Tue with winds becoming ely late in the day in response to the aforementioned cyclogenesis. The various model plumes of the occluded low pressure area are tightening a bit for later in the week. The mean GEFS and ECMWF both occlude the low and eventually bring it across WI Thu nt-Fri. Thus rain chances will continue to increase from Tue nt into Thu with the most widespread rain expected for Wed nt-Thu as the moist TROWAL shifts nwd across srn WI. More uncertainty with the speed and track of the occluded low for Thu nt-Fri nt, but this period could be wetter than what is currently forecast. && .AVIATION... (Issued 848 AM CDT Sun Apr 4 2021) VFR conditions expected to continue into tonight. Some increase in mid-high level clouds today as mid level warm air and moisture advection moves across the area. Shower chances increase late tonight into Monday morning as deeper low level moisture spreads into the area. Leaning toward VFR conditions continuing through Mon morning as well even with isold to sct -shra developing. Can't rule out an isold t-storm as well. Kavinsky && .MARINE... (Issued 425 AM CDT Sun Apr 4 2021) Winds today will be southeasterly over southern Lake Michigan driven by a warm front in association with a low of 29.9 inches over the arrowhead of Minnesota. Winds over the northern end of Lake Michigan will be more northeasterly, driven by a high pressure of 30.2 inches just south of Hudson Bay. Winds will come around to southeasterly over the majority of the lake Sunday night into Monday as the high pressure retreats. Southeast winds will continue through Monday and spotty thunderstorm activity will be possible at times over the southern two thirds of the lake. Strong low pressure of 29.5 will approach from the central plains Tuesday night into Wednesday and winds will come around to northeasterly. Active weather will continue to persist through much of the rest of the week with on and off rounds of rain and some embedded thunderstorms possible. CMiller && .FIRE WEATHER... (Issued 425 AM CDT Sun Apr 4 2021) Elevated fire weather conditions will be present again today as mixing will once again allow for minimum relative humidity values to drop as low as 20 percent over inland locations. These low RH values along with modest southerly and southeasterly wind gusts between 15 and 20 kt and high temperatures in the low to mid 70s will support conditions favorable for fire ignition and spread. CMiller && .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