UPDATE
Issued 1133 AM CDT Fri Sep 20 2024

Wly winds and drier air will continue to gradual move into srn WI this afternoon. High temps in the lower 80s for east central WI and middle 80s elsewhere still looks good. Weak high pressure over IA will then shift across srn WI tnt-Sat AM with low temps mainly from 55-60F. Sly winds and warm, moist advection will then begin Sat afternoon as a n-s sfc trough/cold front approaches from the west. This front extends swd from a strong upper wave and well developed sfc low over Manitoba and Ontario.
High 850 mb dewpoints will surge back into the area from the sw with negative showalter indices developing along with marginal MLCAPE. South central WI may see initial shower and storm development by mid to late afternoon, but with increasing chances through the evening and overnight for all of srn WI as the cold front passes.

Gehring

SHORT TERM
Issued 418 AM CDT Fri Sep 20 2024

Today through Saturday:

As the upper-level trough pushes eastward, the last of the overnight showers and storms will follow suit and push east out over the Lake Michigan by daybreak. The weak cold front will not be far behind the precip and will slide through southern WI this morning. Expect westerly winds and drier airmass to push in behind the front as surface high pressure briefly builds across the area. However, southern WI will still see above normal/summer like temps today given the deeper mixing of warmer air aloft and ample sunshine. Still looking at highs to top off in the low to mid 80s this afternoon. As the high shifts east overnight, winds are progged to become light/calm and paired with mostly clear skies, will see temps drop into the mid 50s to low 60s. High pressure will push east for Saturday and southerly flow will return to southern WI. Once again will see above normal/summer-like temps in the mid to upper 80s.

Wagner

LONG TERM
Issued 418 AM CDT Fri Sep 20 2024

Saturday night through Thursday:

As southern WI "enjoys" the summer-like pattern, another upper- level trough is progged to dig across the northern Plains and skirt the Upper-Midwest overnight Saturday and Sunday. The associated surface low is progged to track across Manitoba/Ontario toward Hudson Bay, which will drag another cold front across WI Saturday night into Sunday. Expect moisture to advect into the warm sector ahead of the front and bring another bout of precipitation to southern WI. Thinking there will be better potential to see a bit more coverage of rainfall/storms with this weekend system given the frontal forcing paired with mid-level dCVA ejecting out ahead of another upper-level trough working its way from the the Desert Southwest into the Central Plains. Both the EPS and GEFS along with the NBM all prog a 50-70% chance of southern WI seeing a half an inch or more of rainfall across southern half of the CWA (generally south of I-94) within the 24hr period ending Sunday evening. Higher amounts approaching 1 inch will be possible, especially for areas along the Cheddar Curtain into IL, but chances remain less than 40% for southern WI at this times.

Additional shower and storm chances will continue through early next week as a series of shortwave trough traverse across the region. However, as we head into next week models differ in timing and track of these features. Thus uncertainty remains, but nevertheless the pattern looks more active through at least Tuesday. Otherwise, the return of more seasonal/near normal temps are expected behind Sunday's cold front and this trend continues through next week. Looking at daily highs in the 70s with overnight lows in 40s/50s.

Wagner

AVIATION
Issued 1133 AM CDT Fri Sep 20 2024

Areas of MVFR Cigs ending early this afternoon north of MKE.
Otherwise VFR conditions this afternoon through Sat other than a brief period of fog at sunrise Sat in the lower WI River Valley and other low lying areas.

Gehring

MARINE
Issued 418 AM CDT Fri Sep 20 2024

Low pressure centered over Manitoba will gradually lift into the Hudson Bay today. This low to the north will drag a weak cold front across Lake Michigan through this evening where southerly winds today will turn more westerly overnight into Saturday. Will see a broad area of high pressure build in behind the front for Saturday before winds turn back to the south and pick up ahead of another low pressure. Expect this low to lift across Manitoba/Ontario and deepen overnight Saturday into Sunday dragging another cold front across Lake Michigan. Will once again see southerly winds turn more west-northwesterly behind the front during the day Sunday. Northerly winds will continue into the the start of next week as high pressure builds across the Upper Great Lakes region.

Wagner

MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM...None.