849
FXUS63 KMKX 181610 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1110 AM CDT Tue Jun 18 2024

.KEY MESSAGES...

- Small chances (15 to 20 percent) for showers and storms in
  southern and southeastern parts of the area this afternoon.

- Chances (30 to 40 percent) for showers and storms overnight
  into Wednesday night.

- Heat index values will be between 95 and 100 degrees this
  afternoon. Hydration and frequent breaks are advised if
  working outdoors.

- Dangerous swim conditions are likely into tonight at Lake
  Michigan beaches in Sheboygan and Ozaukee Counties.

&&

.UPDATE...
Issued 1110 AM CDT Tue Jun 18 2024

Any lingering light showers or sprinkles will move out of far
southeast Wisconsin, as a shortwave trough shifts out. Low
clouds are lingering across parts of the area, and may linger
for several more hours before scattering out by middle
afternoon. Confidence is low in how long it may take to mix out
these low clouds, which would affect high temperatures and
subsequent instability.

If they linger through the afternoon, high temperatures and
instability will be reduced. Kept highs in the 90 to 92 degree
range for the most part, but may need to adjust down if the low
clouds persist. Heat index values in the middle to upper 90s are
expected if the forecast highs are reached. Onshore winds from
Port Washington north into Sheboygan will keep those areas
cooler.

Forecast high temperatures will be close to convective
temperatures, especially in southern and southeastern parts of
the area. If these highs do occur, then widely scattered pop-up
showers and storms are possible to occur. There is enough mean
layer CAPE to possibly bring gusty winds with any storms. Deep
layer bulk shear is quite weak, around 15 knots or less. So,
would expect any showers and storms to be fairly short-lived.

Beach Hazards Statement remains in effect until later tonight
for the Sheboygan and Ozaukee County beaches. Gusty south winds
will bring waves up to 4 feet for these beach areas, which will
result in dangerous conditions for being in the water.

There are better chances for showers and storms (30 to 40
percent) overnight into Wednesday night, as a cold front sags
southeast into the area and washes out. Generally weakening
showers and storms from the west overnight may shift into the
western parts of the area. This may linger into Wednesday
morning.

Clouds associated with this activity may linger through the
rest of Wednesday, so there is uncertainty with how much
instability will be available for possible storms later
Wednesday into Wednesday evening. Deep layer bulk shear is
expected to increase to 25 to 35 knots Wednesday afternoon and
evening, so if storms can develop, there is some risk for strong
winds and downbursts to occur. This will be conditional on
clouds scattering out and enough instability developing.

Wood

&&

.SHORT TERM...
Issued 459 AM CDT Tue Jun 18 2024

Today through Wednesday:

This morning, a week wave over the southern end of Lake
Michigan is expected to bring some low clouds to southeastern
WI, along with slight chances for rain (~15%). Any rain that
happens is expected to be widely scattered. Skies should clear
mid morning and the heat should build, with highs in the low
90s, amid dew points in the low 70s. Resulting heat indices will
be between 95 and 100 this afternoon.

In addition to the heat, southerly winds will gust between 25
and 30 mph. At local beaches in Sheboygan and Ozaukee counties,
this will drive a High Swim Risk from high waves and dangerous
rip currents this morning into tonight. A Moderate Swim Risk
will exist in Milwaukee and Racine Counties. Even with the high
heat outside, swimming is not advised.

Overnight, the large ridge over the eastern United States will
lean more latitudinally, allowing for a cold front to make an
approach at Wisconsin from the northwest before washing out.
This cold front will drag showers and storms over central WI
overnight. Through the day on Wednesday, the cold front will
become more of a southwest to northeast oriented stationary
front from Iowa into lower Michigan. Convergence along this
baroclinic zone will drive on and off scattered shower and storm
chances through Wednesday into Thursday. Heat will still linger
south of the baroclinic zone on Wednesday, and much of southern
WI will see highs in the upper 80s to low 90s again.

CMiller

&&

.LONG TERM...
Issued 448 AM CDT Tue Jun 18 2024

Wednesday night through Monday:

Lee troughing over the front range of the Colorado Rockies will
allow for an increase in southerly flow over the plains
Wednesday night into Thursday morning. Sfc WAA will allow
moisture to surge back north and the stationary front should
lift north as a warm front. Through the day on Thursday, sfc
flow along the sfc trough/warm front will allow for east flow
off of the lake, driving a lake modified air mass inland. As a
result, much of southern WI should see a break from the heat,
although conditions will still remain humid with dewpoints
remaining in the mid to upper 60s. Weak scattered shower and
storm activity may occur along the warm front as well.

The WAA will bring another surge of warmth north for Friday and
Saturday with daytime highs on both days in the upper 80s.
Relief may not finally come until a cold front comes through
Saturday night. The NBM paints great PoPs at 70%, suggesting a
line of showers and storms along with the front Saturday night.
Temperatures then cool for Sunday and Monday.

CMiller

&&

.AVIATION...
Issued 1110 AM CDT Tue Jun 18 2024

Low clouds with ceilings of 1800 to 2500 feet AGL continue to
linger across the area, and may linger into or through the
afternoon hours. Uncertainty exists with how long it may take to
get these low clouds to scatter out. South winds will continue
to be gusty this afternoon, before weakening somewhat tonight.
There may be low level wind shear conditions tonight, with
southwest winds around 2000 feet AGL of 40 to 45 knots.

A few showers and storms may pop up this afternoon and early
evening. Weakening showers and storms should move into areas
west of Madison overnight and may spread over the area into
Wednesday morning. Low clouds with ceilings of 1500 to 2500 feet
AGL may spread over the area during this time, and may linger
into the rest of Wednesday and into Wednesday night. There may
be more showers and storms that form along a weakening and
stalling cold front Wednesday afternoon and evening, but
uncertain how much of this activity will occur at this time.

Wood

&&

.MARINE...
Issued 1110 AM CDT Tue Jun 18 2024

Low pressure around 29.5 inches will move from the northern
Plains into northwestern Ontario today. Gusty south winds are
expected today and tonight. A Small Craft Advisory is in effect
through this evening for the nearshore waters, with the gusty
winds and building waves. Gusts over the open waters may reach
30 knots at times this afternoon into tonight, mainly over the
northern portions of the lake.

Some fog may develop at times over the lake into Wednesday,
with the very warm and humid airmass in place.

Winds will then gradually ease early Wednesday morning, and
lighter southwesterly winds are then expected through Wednesday,
as the low continues to move into Hudson Bay. A cold front will
slowly push southward across the lake Wednesday night into
Thursday, shifting winds to the northeast.

Wood

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060 until 4 AM Wednesday.

LM...Small Craft Advisory...LMZ643 until 1 AM Wednesday.

     Small Craft Advisory...LMZ644-LMZ645-LMZ646 until 10 PM
     Tuesday.

&&

$$

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