Sunrise 5:20 AM   Sunset 8:14 PM Moonrise 6:39 PM   Moonset 4:05 AM

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LMZ646 Wind Point Wi To Winthrop Harbor Il- 106 Pm Cdt Tue May 21 2024
.dense fog advisory in effect until 7 pm cdt this evening - ..small craft advisory in effect from 7 pm cdt this evening through Wednesday morning - .
Rest of today - Southeast wind 5 to 10 knots rising to 10 to 20 knots late in the afternoon. Patchy dense fog early in the afternoon. Waves 1 to 2 feet. Tonight - South wind 15 to 20 knots becoming 15 to 25 knots late in the evening, then veering southwest after midnight becoming 15 to 20 knots early in the morning. Scattered showers and Thunderstorms through around midnight. Isolated showers and Thunderstorms after midnight. Waves 3 to 5 feet building to 4 to 6 feet late in the evening, then subsiding to 3 to 5 feet after midnight subsiding to 3 to 4 feet early in the morning. Wednesday - West wind 15 to 20 knots with gusts to around 25 knots becoming southwest 10 to 15 knots with gusts to around 20 knots in the afternoon. Partly Sunny in the morning then clearing. Waves 2 to 4 feet subsiding to 1 to 2 feet in the late morning and afternoon. Wednesday night - West wind 10 to 15 knots becoming southwest 5 to 10 knots in the late evening and overnight. Clear. Waves around 1 foot.

LMZ600
No data

FXUS63 KMKX 211812 AFDMKX

Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 112 PM CDT Tue May 21 2024

KEY MESSAGES

- Marine Dense Fog will continue to decrease in coverage through the afternoon.

- A complex severe weather event is expected today, with multiple rounds of thunderstorms expected. All severe hazards are possible.

UPDATE
Issued 112 PM CDT Tue May 21 2024

Low to mid level warm, moist advection has been maintaining the convection from Iowa into south central WI today. The sfc warm front is beginning to move nwd with a weakening supercell along it over Dane Co. with additional storms along the warm front or outflow over ern IA. Any of these storms will be capable of becoming supercells given deep layer shear of 50 kts and 0-1KM SRH of 200-300 m2/s2 with all hazards possible including tornadoes.

The warm front should move into central WI by early evening as the deepening sfc low over the Mid MO River Valley tracks to just west of KMSP by 00Z Wed. The amplifying upper wave, strong cold front, and a broken to solid line of convection will then sweep across WI this evening. Mdt to strong deep layer shear and strong low level shear is present but there is a limiting factor to the severe potential this evening. A warm layer from 800-700 mb could yield a high LFC and very low 0-3 km CAPE. This warm layer will also contribute to building MLCIN along with the loss of diurnal evening. Although there would still be some tornado risk, damaging winds and hail may be more probable. The warm layer and building MLCIN could actually cause the line to dissipate over far se WI as indicated by some CAMs.

Gehring

SHORT TERM
Issued 448 AM CDT Tue May 21 2024

Today and Tonight:

A busy, rain and stormy, day is in store for Wisconsin today.
The Storm Predictions Center's Severe weather outlook does a good job of reflecting this busy day with a Moderate Rick (4 out of 5 risk) covering portions of southwestern Wisconsin.

With high dewpoints this morning and cooling temperatures, fog has developed across the forecast area with many locations experiencing dense fog. As southerly winds increase and diurnal heating kicks in after sunrise this fog should burn off rather quickly.

Kicking the rain/storm discussion off early this morning there is ongoing convection across northeast Iowa and far western Wisconsin. This ongoing convection is on the leading edge of the Low level jet. Much of this early morning convection is well ahead of these features and is slowly moving northeast.
Southwestern and western Wisconsin will have the best chances the ongoing and slightly developing blob of showers/storms this morning. Much of eastern and southeastern Wisconsin will remain dry with this morning "round".

This afternoon and evening will be the main concerns for any severe weather to develop. The afternoon round of storms will likely be along the leading edge of the warm front. As warm moist air surges northward a few showers and storms are likely to develop. The exact location that storms could fire is a bit muddled due to many models have a very shallow cap in place which limits the location and coverage of any convection during the afternoon. This cap does look to be pretty weak, which means anything that does break it could grow quickly. Strong to severe storms during this afternoon would mostly pose a wind and hail threat. A brief lull between this afternoon and evening rounds will prep the stage for the severe weather potential this evening.

As the cold front passes later this evening the next round of rain and storms will move through. Timing with this has the cold front beginning to move through as early as 6 PM with it exiting the region as late as midnight. While the exact outcome will depend on the duration of the lull between the passage of the warm front and cold front. The air mass in place and the dynamics within this strengthening low pressure system are fantastic. This means that supercells and squall line storm modes are on the table. Lapse rates are steep, CAPE is high, and low level shear/helicity is also very good. Hodographs continue to show the nice curved features you would be looking for on days with good tornado potential. Overall the threat with this evening round is strong winds, large hail and tornadoes.

Patterson

LONG TERM
Issued 448 AM CDT Tue May 21 2024

Wednesday through Monday:

As the low pressure system bringing all of our rain and storms today moves northeast across Lake Superior and into Canada, high pressure will be on its heals for Wednesday and Thursday. The upper level ridging will be building into the Midwest Wednesday afternoon and will continue to influence the region through Thursday. The pressure gradient will remain tight between the exiting low and incoming high pressure resulting in some gusty west winds, and decent cold air advection. Cloud cover should be decreasing throughout the day Wednesday. Considering the warmer temperatures over the previous few days, Wednesday is likely to feel much cooler with the 70 degree high temperatures feeling slight deceiving for some.

Dry weather will continue through Friday morning. Precipitation chances will increase as the next approaching shortwave moves toward the state. Showers and thunderstorms will be possible Friday afternoon through Saturday morning. There is still quiet a bit of uncertainty with this system especially with timing and strength. The GFS is still pretty rambunctious in comparison to other long range models. Its likely that timing of rain will tighten up a bit and that some of the finer details such as QPF and exact location as this system gets closer in time.

Another shortwave looks to be on the horizon as well for Saturday which could be yet another round of showers and storms. Almost like a round two if you will. Showers and storms Friday into Saturday and again Saturday will be supported by two separate shortwave troughs. Still a lot of details to be hashed out here. Thankfully Sunday continues to show promise for being dry as a weak ridge quickly moves through the Great Lakes Region.

Patterson

AVIATION
Issued 112 PM CDT Tue May 21 2024

The Cigs well below 1 kft over far ern WI and nw of Madison will dissipate by late afternoon. Otherwise scattered strong to severe storms will move across south central WI this afternoon followed by a north to south line moving ewd across srn WI for the early to middle evening hours. After the cold front passes MVFR Cigs are expected to develop over much of srn WI and continue into Wed AM before dissipating by afternoon.

Gehring

MARINE
Issued 448 AM CDT Tue May 21 2024

With dewpoints near the air and water temperatures across the southern half of the Lake this morning dense fog has developed.
As dewpoints increase with the passage of the warm front later today, its likely that the dense fog will persist until the cold front moves across the open waters, bringing with it rain and thunderstorms.

South to southeast winds this morning will become breezy as a deepening low pressure system advance from the central plains northeastward toward the upper Great Lakes Region. There will be periods of thunderstorms over the lake, especially the southern portions through Wednesday morning. A Small Craft Advisory is in effect tonight through Wednesday morning due to the gusty southerly winds.

High pressure will build into the Midwest Wednesday and Thursday bringing quieter winds and waves through midweek.

Patterson

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

LM
Dense Fog Advisory
LMZ080-LMZ643-LMZ644-LMZ645-LMZ646-LMZ669- LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874- LMZ876-LMZ878 until 7 PM Tuesday.

Small Craft Advisory...LMZ643-LMZ644...7 PM Tuesday to 4 PM Wednesday.

Small Craft Advisory...LMZ645-LMZ646...7 PM Tuesday to 10 AM Wednesday.

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