Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
438 FXUS63 KMKX 022005 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 305 PM CDT Sun Jun 2 2024 .KEY MESSAGES... - Warm/muggy conditions prevail for the first half of this week. Multiple rounds of showers and thunderstorms Monday through Wednesday. There is a small, conditional potential for severe storms Monday afternoon. - Northwest winds bring cooler and drier air to southern Wisconsin for the second half of this week. && .SHORT TERM... Issued 305 PM CDT Sun Jun 2 2024 Tonight and Monday: Light winds and high dewpoints may lead to some patchy fog tonight, but increasing high clouds and slightly increasing southeast winds through the night should keep widespread dense fog from developing. Although, river valleys and marshy areas have a chance at dense fog. Lows should be in the mid 50s east thanks to lake-cooled air that will spread inland with the lake breeze this evening. Inland lows will be in the lower 60s where dewpoints will be higher. There is still uncertainty about how the radar might look Monday. The generally thinking is that the thunderstorms developing in Nebraska this afternoon will evolve into thunderstorm complex that tracks across Iowa overnight. The convection with this is expected to diffuse over northern IL and/or southern WI Monday morning. Meanwhile, a shortwave trough swinging across the Northern Plains and fueled by the low level jet overnight should produce scattered thunderstorms that are also weakening as they reach western WI Monday morning. Depending on where the boundaries from the overnight convection stall, and also on how much cloud debris is left over, southern WI could be the focus for a few areas of thunderstorms by midday Monday. So we might see some dying showers and perhaps a rumble of thunder Monday morning, especially west of Madison. Then any clearing skies will help overcome the cap within our moist environment in the afternoon and thunderstorms could freely convect, especially along any remnant boundaries or areas of convergence. The NAM is showing the potential for 2000 j/kg of CAPE and bulk shear over 35 kt, which would be sufficient for severe storms. This is a little overdone due to too high of dewpoints, but the idea is that we have a chance at severe if conditions come together just right. The SPC Marginal Risk seems appropriate at this time. With precipitable water values of 1.5 to 1.8 inches over our area by Monday afternoon, heavy rain is a threat with any clusters of storms that develop. The precip should be diminishing Monday night, although the GFS wants to fire convection along a stalled 850mb boundary draped across southern WI and on the nose of a weak low level jet. This looks like a less likely scenario at this time. Cronce && .LONG TERM... Issued 305 PM CDT Sun Jun 2 2024 Tuesday through Sunday: There will be two areas of forcing to watch for when predicting our storm chances on Tuesday. The first one is a forecast storm complex that will be moving across the mid Mississippi River Valley Monday night that could lift into southern WI Tuesday afternoon. The GFS has this idea but the ECMWF and NBM keep this complex over IL. The other area is vorticity advection ahead of a stronger shortwave trekking along the US/Canadian border in the northern Plains. Warm air advection, moisture advection, and vorticity advection well out ahead of this upper wave may produce scattered showers and thunderstorms over southern WI Tuesday afternoon. The high precipitable water values in the 1.5 to 1.8 inch range will persist through Wednesday, so heavy rain will continue to be a threat wherever there is convection. All of this forcing should keep us fairly cloudy, which will help keep down our instability and therefore our chance for severe storms. The Northern Plains upper wave is expected to push through WI early Wednesday. Gusty northwest winds will usher drier air into the region. Look for scattered showers during the afternoon due to steep low level lapse rates with the cyclonic flow aloft. There is uncertainty about how that upper wave will act over the Upper Great Lakes after Wednesday. The GFS tries to keep the closed upper low overhead while the ECMWF moves it to the east coast. The bottom line is that temperatures will be cooler for the last half of the week. Cronce && .AVIATION... Issued 305 PM CDT Sun Jun 2 2024 Widespread diurnal cumulus is hanging on across southern WI, although most sites have ceilings above 3500 ft now. Look for increasing high clouds tonight. Decaying areas of showers with a small chance for thunder should roll into portions of southern WI from the west Monday morning. There is a better chance for storms Monday afternoon and evening, especially over southeast WI. Severe storms are conditional based on how much sunshine we can manage and a few other factors. Cronce && .MARINE... Issued 305 PM CDT Sun Jun 2 2024 Dense fog is possible over the south half of Lake Michigan again tonight since the dewpoints are in the mid 50s over the relatively cooler lake water. Look for light and variable winds to increase out of the southeast Monday. Storms are possible Monday afternoon and evening, and at times through Wednesday morning. Light winds will persist through Wednesday morning. Look for gusty northwest winds in the wake of a cold front Wednesday afternoon. Gusts may exceed Small Craft Advisory levels near the lakeshore during this time. Cronce && .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