NWS-Milwaukee/Sullivan Forecast Discussion

 

						FXUS63 KMKX 192010
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
310 PM CDT Wed Jun 19 2024

.KEY MESSAGES...

- Scattered showers and storms are forecast into early this
  evening for most of southern Wisconsin. May see gusty winds
  with the stronger storms over southeast Wisconsin. On and off
  thunderstorm chances will then continue into this weekend.

- Heat index values will be in the middle 90s over southeast
  Wisconsin until early this evening. Head index values will be
  back in the middle 90s Friday and Saturday.

- A moderate swim risk may occur Thursday morning at Sheboygan
  County beaches.

&&

.SHORT TERM...
Issued 310 PM CDT Wed Jun 19 2024

Tonight through Thursday night:

Cold front will continue to shift southeast through the area and
into northern Illinois into this evening. Scattered showers and
storms continue to develop and slowly shift northeast through
parts of the area, both near the front and where convective
temperatures may be reached. CAMs continue to support the
scattered showers and storms into early this evening across the
area.

The best instability will be toward southeast Wisconsin, where
mean layer CAPE up to 1500 J/kg or so is expected, perhaps
higher in spots. Areas further northwest may have more clouds
move in with the front, so mean layer CAPE there will be lower.
0 to 6 km bulk shear values should increase by early evening
into the 20 to 25 knot range, though the southeast parts of the
area will be on the lower end of this range.

This would mean short-lived airmass thunderstorms that have
some downburst wind potential, as forecast soundings are showing
some inverted V structures to them in the low levels. In
addition, cannot totally rule out a landspout spinup, as 0 to 3
km CAPE values are above 100 J/kg along the front and are
coinciding with some surface vorticity with the front. The
probability is low, but not zero. We will keep an eye on this.

Heat index values in the lower to middle 90s are expected to
linger in southeast Wisconsin until early this evening. Cooler
but still mild temperatures are expected later tonight into
Thursday, as winds shift northeast and lower clouds move in.
Some fog and low stratus clouds may also push onshore near the
lake overnight into Thursday morning. The clouds may linger for
a good part of Thursday.

Chances for showers and storms will continue at times overnight
into Thursday night, as some modest 850 mb warm air advection
and convergence/frontogenesis response lingers near the area.
Areas near the Illinois border may see the best chances for
storms Thursday afternoon and evening, as some better low level
frontogenesis with the front just to the south of the area
interacts with warm and unstable air. May see some gusty winds
with any of those storms as well.

&&

.LONG TERM...
Issued 310 PM CDT Wed Jun 19 2024

Friday through Wednesday:

Models are generally showing the warm front shifting north
across the area Friday into Friday night, before moving further
north for Saturday. Chances for showers and storms will remain
during this period. The area should get into the warm sector and
become very warm and humid again on Saturday with southwest
winds. A cold front looks to shift east across the region
Saturday night, bringing another chance for showers and
thunderstorms. Will have to watch this period for stronger
storms, though deep layer bulk shear values are only 20 to 25
knots at this time.

There may be a lull in precipitation chances Sunday into Monday,
as high pressure may move through the region. Temperatures look
to remain near to above normal into next week per ensemble
trends. Chances for showers and storms may return for the middle
of next week as well, as ensembles are showing a generally wet
Tuesday into Wednesday period.

Wood

&&

.AVIATION...
Issued 310 PM CDT Wed Jun 19 2024

Scattered showers and storms are expected to continue into early
this evening, as a cold front moves southeast through the area.
Gusty winds are possible with the storms, with locally reduced
visibility values.

Gusty southwest winds ahead of the front will shift west to
northwest and weaken by early this evening, as the cold front
moves through. Winds will then shift north by later this
evening and northeast later tonight, with east to northeast
winds on Thursday.

Cooler temperatures are expected tonight into Thursday,
especially near Lake Michigan. Some showers and storms may
occur at times overnight into Thursday night, perhaps more
toward the Illinois border areas on Thursday.

General VFR ceilings into this evening should drop to 500 to
1200 feet AGL Thursday morning, as low stratus clouds move into
the area off of Lake Michigan. These ceilings should slowly
rise Thursday afternoon. In addition, fog with 2 to 5 mile
visibility may form overnight into Thursday morning, with some
fog moving onshore from Lake Michigan for terminals near the
lake. Locally lower values are possible.

Wood

&&

.MARINE...
Issued 310 PM CDT Wed Jun 19 2024

A cold front will gradually sink southeast across Lake Michigan
into tonight. South to southwest winds will shift northwest to
north this evening, and northeast to north later tonight into
Thursday. Patchy to areas of marine fog may form tonight and
linger into Thursday morning, with some dense fog possible.

North to northeast winds should then linger into Friday, as high
pressure around 30.4 inches moves from Lake Superior into Ontario.
Gusty south to southwest winds are then anticipated to return for
Saturday into Saturday night, as low pressure around 29.5 inches
shifts into the region.

Wood

&&

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

$$

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