DISCUSSION
Issued at 434 AM CDT Sat Jul 27 2024

Short Term
Today
Tonight...and Sunday

Southerly winds will bring warmer temperatures into Wisconsin today, but humidity levels will be low enough for it to be pleasant enough, especially across the Fox Valley and lakeshore counties where dewpoints should be lowest. Low level warm advection and increasing moisture will produce increasing clouds across central and northcentral WIsconsin today, with skies remaining mostly sunny further east. Highs today will be a few degrees above normal in most areas.

Dry air circulating around the surface high across the Lower Great lakes, and mostly clear skies will allow temperatures to fall to near or just above normal levels tonight.

Sunday will be mostly cloudy and there is a chance of thunderstorms across central and east central Wisconsin as a weak upper trough approaches from the Central Plains. It will feel much more humid with dewpoints climbing through the 60s during the day. Temperatures will be a few degrees above normal.

Long Term...Sunday Night Through Friday

Main highlights from this forecast period revolve around multiple chances for showers and thunderstorms throughout the work week, paired with above normal temperatures and humid conditions.

Precipitation...Showers and thunderstorms will likely be ongoing into Sunday evening as a weakening shortwave lifts northeast across the state. However, this precip will come to an end rather quickly into the evening/night, as forecast soundings indicate low to mid- level dry air moving into the area. A brief break in the precip looks to occur through Monday morning before the next shortwave phases with its predecessor. This phasing has resulted in models generating areas of convection in different locations across the Upper Midwest. Where and how these areas of convection evolve and progress eastward for the remainder of Monday will be the main challenge to iron out over the next few days. Despite these discrepancies, it does still appear the forecast area will see showers and thunderstorms sometime between Monday afternoon and night, but the finer details of who will see the greatest amount of rain, when it will occur, and the severity of the thunderstorms remains uncertain. Guidance is indicating the main shortwave will linger over the western Great Lakes on Tuesday, which may generate some diurnally driven showers and storms in far eastern WI.

Broad upper-level ridging will attempt to build over the area Tuesday night, but won't last long as models are showing signs of multiple shortwaves riding the ridge throughout the rest of the work week. However, there are large discrepancies in the timing and placement of these shortwaves. Anticipate the forecast area will see precip at some point between midweek and the end of the week, but it is too difficult to determine any further details at this time.

Temperatures...Despite the several chances for precip throughout this forecast period, the warm, moist airmass producing this precip will also result in above normal temperatures and humid conditions.
Anticipate highs to mainly top out in the middle to upper 80s each day, with a few spots potentially reaching 90 degrees. Dew points will generally be in the middle to upper 60s, with low 70s on some days. While heat index values will be in the upper 80s to low 90s, the risk for excessive heat remains low.

AVIATION
for 12Z TAF Issuance Issued at 628 AM CDT Sat Jul 27 2024

A weak low level jet was producing clouds with MVFR ceilings west of an Iron Mountain to Antigo to Stevens Point line at 11UTC this morning. These clouds should gradually diminish as they move east this morning, and should become scattered by the time they get to OSH/ATW/GRB. Assuming this is the case, there will be VFR conditions over the entire area this afternoon through tonight.

VFR conditions are likely to continue Sunday morning, then an upper level trough approaching from the Central Plains will bring a chance of thunderstorms and MVFR conditions roughly south of a Wausau to Green Bay line in the afternoon.

Warmer and more humid air streaming up from the south will likely produce MVFR/IFR conditions and scattered showers or thunderstorms Sunday night.

OSH
VFR conditions are expected today and tonight. Scattered clouds with bases around 3500 feet will arrive later this morning.
They could become broken for a couple hours around noon, and then scatter out again in the afternoon. Mostly clear skies are likely overnight, but clouds will return Sunday morning, with a chance of thunderstorms and MVFR conditions in the afternoon as an upper trough approaches from the Central Plains.

GRB WATCHES/WARNINGS/ADVISORIES
None.