Sunrise 5:40 AM   Sunset 7:54 PM Moonrise 2:04 AM   Moonset 10:37 AM

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LMZ542 Sturgeon Bay To Two Rivers Wi-two Rivers To Sheboygan Wi- 942 Am Cdt Tue Apr 30 2024
Today - W wind 5 to 10 kts backing sw in the afternoon. A chance of sprinkles in the morning. Waves 2 ft or less. Tonight - SE wind 5 to 10 kts veering S 10 to 20 kts after midnight. A chance of rain showers in the evening, then rain showers and a slight chance of Thunderstorms after midnight. Waves 1 to 3 ft building to 2 to 4 ft early in the morning. Wednesday - W wind 10 to 20 kts with gusts to around 25 kts. Partly cloudy. Waves 2 to 4 ft subsiding to 1 to 3 ft in the afternoon. A small craft advisory may be needed. Wednesday night - W wind 5 to 10 kts veering N after midnight. Partly cloudy in the evening then becoming mostly cloudy. Waves 2 ft or less.

LMZ500
No data

FXUS63 KGRB 301148 AFDGRB

Area Forecast Discussion National Weather Service Green Bay WI 648 AM CDT Tue Apr 30 2024

Updated aviation portion for 12Z TAF issuance

KEY MESSAGES

- Active weather pattern to bring a round of showers and embedded storms this evening into early Wednesday, with widespread rain and a few thunderstorm possible late Wednesday night through Friday.

- Gusty west winds up to 40 mph expected on Wednesday. While recent rains will limit fire weather concerns, the gusty winds will bring a threat of sporadic power line fires.

- Due to recent/upcoming rainfall, rivers and streams will be on the rise this week, with some reaching bankfull stage.

DISCUSSION
Issued at 343 AM CDT Tue Apr 30 2024

Short Term
Today
Tonight...and Wednesday

Today...plenty of clouds are expected to start the day as low pressure slowly lifts north/east away from the region. A few sprinkles, pockets of drizzle and/or light fog will lingering into the morning hours, especially across northern WI. Look for decreasing clouds from south to north through the late morning and afternoon hours as drier air briefly works in, but additional clouds will spread in from the west later in the afternoon as the next system approaches. West winds will generally be in the 10-20 mph range through the early afternoon, then will decrease and shift to the south/southeast. Highs will climb into the upper 50s and 60s for most locations, with a 70 possible in the SW CWA and slightly cooler readings near the shores of Lake Michigan.

Tonight...the brief break in clouds (and rain) will end quickly this evening as the next in a series of low pressure systems and shortwaves cross the Great Lakes. Showers with some embedded storms are expected to spread west to east across the area, reaching central WI between 00-03z and 04-07z over eastern WI.
The activity looks to exit by 12z Wednesday. Surface-based instability is forecast to stay just to our south, but MUCAPEs do climb to around 700 J/kg, highest across central WI in the mid- evening. While severe weather is not expected, as the LLJ brings 40+ kt winds aloft, some gusty winds could accompany any of the showers or storms, along with some small hail as wet-bulb heights will be on the low side. Models in general agreement bringing between 0.40-0.75" of rain across much of central and north central WI, with locally higher amounts over an inch are possible if/where any storms track over the same location (PWATs around one inch). Lower amounts under 0.25" in the Fox Valley and lake shore. Lows will be in the 40s to low 50s.

Wednesday...lingering clouds and possibly some light showers or sprinkles are expected early in the day, with a period of partly to mostly sunny skies for most locations by mid-late morning.
Additional clouds are expected later in the day. West winds will gust to 40 mph as the pressure gradient will remain tight behind the departing low and good mixing will bring down the stronger winds. Highs look to range from the 60s across north-central WI to the upper 60s to lower 70s over eastern WI where some downsloping should help offset any CAA.

Afternoon relative humidity readings should drop into the 30s across most locations, lowest in the sandy soil regions where some upper 20s are possible. Recent/expected rainfall, along with the continued green-up, will limit overall fire weather concerns; however, the gusty winds will bring a threat of sporadic power line fires. And with pine fuels at/near their seasonal peak, could have some issues if any fires are able to start.

Long Term...Wednesday Night Through Monday

The potential for areal flooding will be the main impact during the extended period as several chances for showers and storms are forecast for the latter half of this week and this weekend.
Several area rivers are already on the rise with this weekend rainfall.

First chance for precipitation is progged to arrive Wednesday night as a deepening through developing over the Northern Rockies pulls a lee side cyclone northeast into the upper Mississippi Valley. Rain shower are expected to become widespread Thursday with the heaviest rain Thursday afternoon and evening as a right rear jet quad and mid- level PV anomaly move over the region along with enhanced poleward moisture transport resulting in PWAT values of 1-1.5". Event total QPF is expected to range from around 0.5-1" with locally higher totals possible where the heavier showers develop. There is a small chance for isolated embedded thunderstorms Thursday afternoon through early Friday morning, mainly along a warn front forecast to set up across central and east-central WI. The threat for any storms that do develop becoming severe looks low giver MUCAPE values peaking around 200-400 J/kg and effective shear values around 10-20kt.
Caveat here is if the warm front sets up further north allowing the warm sector to pusher further north a few stronger storms may be possible Thursday evening. Showers and a few weak storms may linger into Friday morning as a cold front pushes through through the region. Expect dry and breezy conditions behind the front with westerly wind gusts reaching 20-30 mph at times, highest in central WI.

Ensemble guidance is showing a second disturbance developing in the wake of the departing main vertically stacked low. The timing of this feature remains uncertain as some ensemble members have it arriving as early as Saturday afternoon while some keep the region dry until Sunday morning. Current guidance is not showing much in the way of convective potential with this system, however given the days 5 and 6 time frame that could change with later forecasts.

Temperatures are forecast to remain steadily a few degrees warmer that normal through the extended period with highs each day ranging form the mid 50s to around 70 degrees. Low temperatures are expected to fall into the upper 30s to around 50 degrees each night. Frost/Freeze headlines will be issued as needed beginning May 1st for central and east-central WI and May 7th for northern WI.

AVIATION
for 12Z TAF Issuance Issued at 644 AM CDT Tue Apr 30 2024

A mix of VFR and MVFR conditions will continue this morning with a few patches of drizzle and sprinkles possible. Look for improving conditions through the morning and afternoon hours, then conditions will deteriorate this evening as a fast moving low pressure system pushes into the area, spreading rain across the entire area. The heaviest rain and best chance for thunder will be in central (AUW/CWA) and north central WI (RHI). A low level jet will increase winds at 2000 ft late tonight into early Wednesday, creating LLWS. Surface winds will be westerly through early afternoon, then turn south/southeast for a time this afternoon and evening, before shifting back to the southwest/west overnight into Wednesday morning. Gusty west winds up to 35 kts are expected on Wednesday.

GRB WATCHES/WARNINGS/ADVISORIES
None.

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