568
FXUS63 KMKX 161538
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1038 AM CDT Thu May 16 2024

.KEY MESSAGES...

- Scattered thunderstorms are expected from late morning into
  the early evening. Some could be strong to severe with small
  hail and gusty winds as the main threats. A marginal risk (1
  out of 5) has been issued for most of southern WI.

- Summer-like temperatures and mostly dry Fri-Sun.

- A wet and unsettled period for Mon-Tue.

&&

.UPDATE...
Issued 1015 AM CDT Thu May 16 2024

Higher dew points are working their way into southwest
Wisconsin at the moment behind a week warm frontal boundary,
with mid 50 degree dew points being observed in Grant County and
along the Mississippi River and low 60s observed over northeast
to eastern Iowa. As time goes on this morning, warm moist
advection on southerly winds should bring these better dewpoints
north into a larger area of southern Wisconsin as temperatures
rise into the upper 60s to low 70s. SBCAPE of 1000 to 1500 J/kg
will result, and with an advancing cold front and shortwave
aloft, scattered thunderstorm development may occur between 12
to 2 PM in western to central WI.

Gusty winds and hail appear to be the main threats, but storms
actually reaching severe criteria (quarter sized hail stones,
60 mph winds) may be isolated, owing to a skinny CAPE profile,
marginally supportive mid-level lapse rates, and marginally
supportive effective bulk shear. The already conditional, low
tornado threat appears even lower this morning owing to less
projected low to mid level SRH and an unfavorable warm front
orientation with respect to storm motion.

Storms should begin to taper off/exit east over Lake Michigan
between 6-9PM this evening.

CMiller

&&

.SHORT TERM...
Issued 400 AM CDT Thu May 16 2024

Today through Saturday:

A shortwave trough slightly amplifying and digging into MN will
move across the nrn half of WI today then lift newd into
Ontario tnt. At the surface, the warm front approaching the MS
river will quickly lift into central WI this afternoon then
stall as a weak wave of low pressure moves along it. A weak sfc
trough/wind shift will then follow for late afternoon and early
evening over srn WI. A plume of PWs of 1-1.2 inches and MUCAPE
of 1000-1500 J/KG is expected for the afternoon along with deep
layer shear of 30 kts. At this time it still appears shower and
storm development is likely with moist low to mid levels
resulting in little to no capping, in addition to the lift from
a meaningful band of PVA extending south from the main
shortwave trough. Additional isolated development will be
possible during the early evening along the weak wind shift. The
aforementioned CAPE and shear combo would support marginal
conditions for SVR storms with any short segment lines that may
develop or possible supercell structures.

Fog may then become a concern tnt especially where any
meaningful rain occurs as the sfc trough dissipates and good
radiational cooling conditions develop where clearing occurs.
Weak high pressure will then prevail over Lake MI Fri-Fri nt
with 500 mb height rises over the Great Lakes. Any fog should
quickly burn off Fri AM followed by summer like temps away from
the lake. Temps will then warm into the lower 80s well inland
from the lake for Sat as an upper ridge builds over the Great
Lakes in response to an occluding low over Manitoba.

Gehring

&&

.LONG TERM...
Issued 400 AM CDT Thu May 16 2024

Saturday night through Wednesday:

Filling low pressure is trending northward due to a nose of high
pressure nudging in from the central Plains on Saturday night,
leading to diminished chances for rainfall along an associated
cold front. Still, an isolated shower or thunderstorm is possible
in west-central Wisconsin during the evening to overnight hours
before the frontal feature weakens. Dry and sunny conditions with
light northerly winds are then expected through Sunday, leading to
temperatures near 80 degrees across much of southern Wisconsin.
Light winds may lead to a lake breeze component, keeping shoreline
counties cooler.

Developing low pressure in the central and northern Plains then
brings a weak warm frontal feature through southern Wisconsin late
Sunday night into Monday, with showery activity increasing into
Monday morning. Low pressure follows general steering flow
northward around the surface high, bringing chances for
thunderstorms throughout Monday afternoon as the surface trough
pivots slowly eastward. A wet, warm pattern continues through
Tuesday as additional shortwaves propagate northeastward along the
previously initiated trough. As high pressure retreats eastward on
Wednesday, expect precipitation to exit. However, wrap around
precipitation may produce a few additional showers through
Wednesday.

Gehring

&&

.AVIATION...
Issued 1035 AM CDT Thu May 16 2024

Light southerly winds will persist today among mainly VFR
background conditions. Scattered showers and storms are expected
to develop this afternoon, which may drop vis and ceiling
categories in their vicinity. Skies should then clear some this
evening following storms, but fog may form, especially along the
lakeshore, leading to reductions in vis down to 1-2 miles.

CMiller

&&

.MARINE...
Issued 400 AM CDT Thu May 16 2024

Light east to northeast winds early this morning will veer to east
to southeasterly later this morning and last through the day. This
will occur as a weak trough of low pressure moves across Wisconsin
then dissipates over the lake tonight. Weak high pressure will
then prevail over the lake Friday and Friday night. Areas of dense
fog will be possible over the lake tonight into Friday as a
relatively humid airmass flows over the cold waters.

Gehring

&&

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

$$

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