Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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026 FXUS63 KGRB 150350 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1050 PM CDT Fri Jun 14 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - Well above average temperatures are expected from Sunday into the middle of next week. Heat indices may surpass 90 degrees at times. - A round of showers and thunderstorms is expected across the area Saturday night into Sunday morning. Locally heavy rainfall is likely across northern Wisconsin, with amounts over an inch possible. High rainfall rates could result in localized street flooding and ponding of water on roads. - There is a Marginal Risk of severe thunderstorms across much of the area Sunday afternoon and Sunday night. Some of the storms could produce damaging winds and large hail. - On and off chances for thunderstorms will continue next week, although there is still some uncertainty with timing. Due to increasing heat and humidity, some stronger storms and locally heavy rainfall may be possible. && .DISCUSSION... Issued at 305 PM CDT Fri Jun 14 2024 Short Term...Tonight and Saturday High base cumulus clouds across northern and central Wisconsin should dissipate early this evening as the sun sets, with mostly clear skies overnight. The dry air will allow for another cool and pleasant night with lows a degree or two below normal. Saturday will start out sunny, but middle and high clouds will increase during the afternoon in the warm advection ahead of a warm front. Showers are possible west of highway 51/39 in the afternoon. The showers will be falling into dry air, so rainfall amounts will be minimal. Highs will be close to normal for this time of the year. Long Term...Saturday Night Through Friday Forecast into next week continues to be volatile regarding potential for some strong to severe storms with a ring of fire pattern expected to build in across the CONUS. The SPC has highlighted north-central and northwest Wisconsin under a marginal risk for receiving severe weather on Sunday, although there are still some questions about timing and airmass recovery. Heavy rainfall will likely be a concern given abundant moisture and an open Gulf. Hence, the WPC has put most of northeast Wisconsin under a marginal/slight risk of receiving excessive rainfall Saturday and Sunday. Saturday night through Sunday precip chances... Saturday night/Sunday morning convection remains a source of uncertainty regarding storm potential later Sunday afternoon and evening. Some storms will be possible out ahead of the warm front Saturday evening through Sunday morning, especially as the nocturnal LLJ ramps up to 50+ knots and moisture convergence results in modest elevated instability. However, convective activity early Sunday morning may act to shunt the northward movement of the warm front later in the day. This scenario would affect how warm temperatures are able to get Sunday afternoon, and in turn the possibility of storm re-development, due to the effect of lingering cloud cover and departing precip. Model soundings are quite aggressive with instability (3000 to 4000+ J/kg of CAPE) Sunday afternoon, although current thinking is that this will largely depend on how the warm front behaves. Additionally, some models are suggesting that any thunderstorm activity would be capped due to stable flow off of Lake Michigan. Rest of the extended... Attention then turns to storm chances on Monday as a trailing cold front moves across the upper Midwest. With an open Gulf and temperatures possibly surging into the low 90s across the warm sector, strong storms with locally heavy rainfall will be possible across portions of central to north- central Wisconsin Monday afternoon. Will continue to monitor severe potential as we get closer to the event. As the cold front departs to the southeast Monday evening, a robust trough west of the Rockies will carve out a high amplitude ridge over the eastern US, placing much of the Midwest under a warm and moist southwesterly flow regime through mid-week. This ring of fire pattern will bring about the first heatwave of the summer, with heat indices early in the week potentially climbing into the low to mid 90s. && .AVIATION...for 06Z TAF Issuance Issued at 1050 PM CDT Fri Jun 14 2024 VFR conditions are expected tonight int Saturday morning with only a few mid to high clouds drifting across the region. Some high-based showers or sprinkles will be possible Saturday afternoon, with the best chance of any measurable precip being north/west of the Fox Valley. Higher chances for widespread showers and a few storms arrives after sunset, especially across central and northern WI. Then a period of showers with embedded storms is expected across the entire area after midnight. Heavy rain appears to be the greatest risk with these storms, with mainly MVFR and IFR conditions. Will hold off on thunder mention as threat will remain under 20% until after 06z Sunday. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....RDM/Goodin AVIATION.......Bersch