073
FXUS63 KMKX 060916 CCA
AFDMKX

Area Forecast Discussion...CORRECTED
National Weather Service Milwaukee/Sullivan WI
416 AM CDT Mon May 6 2024

.KEY MESSAGES...

 - Periods of showers and thunderstorms remain likely Tuesday. A
   few storms could be strong to severe during the afternoon and
   evening hours.

 - Small craft conditions are expected Tuesday.

 - Unsettled weather continues into mid-week, with additional
   showers and storms possible Wednesday afternoon through
   Thursday.

&&

.SHORT TERM...
Issued 409 AM CDT Mon May 6 2024

Today through Tuesday:

Synopsis/Mesoanalysis: GOES water vapor imagery places a pronounced
upper level low over the Four Corners vicinity early this morning.
Wedged between the aforementioned upper low and shortwave ridging
over the northern Mississippi Valley, an area of diffluent upper
level flow has been analyzed over the Northern Plains vicinity.
Positioned beneath said upper level diffluence, well-defined lee
troughing is apparent over the WY & MT Front Range. The Four Corners
upper low is forecast to advance northeast toward the international
border today, with attendant DPVA encouraging surface cyclogenesis
along MT-ND-SD border vicinity this afternoon and evening. The
surface low will linger over this general area through the duration
of the short term period, undergoing the occlusion process along the
international border Tuesday afternoon and evening. An attendant
occluded front is forecast to extend southeast of this surface low,
approaching southern Wisconsin from the southwest Tuesday afternoon
and evening. Precise progress of the front will depend upon how
quickly a round of showers and embedded thunderstorms passing
through the region Tuesday AM vacates to the east. Despite the
remaining uncertainties regarding precise occluded front
positioning, at least scattered redevelopment of showers and
thunderstorms is anticipated on Tuesday afternoon given the presence
of the boundary, mild low level temperatures along/behind it, and
upper level diffluence lingering across the Western Great Lakes.
Some of these storms could become strong to severe, with trends to
be closely monitored over the coming forecast cycles.

Today & Tonight: Pleasant conditions will continue locally, with
mostly sunny skies promoting high temperatures in the low-mid 70s
away from Lake Michigan. Conditions will turn unsettled to our south
and west in the Plains, where an expansive line of scattered showers
and storms will develop ahead of the ejecting Four Corners
disturbance this afternoon. Much of this activity will persist into
the overnight hours tonight, with the northern end moving into the
mid-upper Mississippi Valley as it gradually weakens approaching
daybreak Tuesday. Anticipate that some of this activity will begin
to nudge into our southwestern zones prior to daybreak Tuesday,
which has been accounted for with increasing precip probs primarily
west of Madison following 1 AM Tuesday. Given that storms will be
well into their weakening/decaying phase, severe weather is not
anticipated at this time.

Tuesday: Supported by upper diffluence overspreading the western
Great Lakes, the decaying showers/storms entering our southwestern
zones prior to daybreak will continue to move east across the area
during the morning hours. Given an abundance of cloud cover, poor
mid-level lapse rates, and the early day timing, don`t currently
expect any of these storms to be strong/severe. Attention will then
turn west/behind of the vacating morning activity during the
afternoon hours, when scattered redevelopment of showers and storms
is possible. Potential redevelopment will be facilitated by the
arrival of the occluded front discussed above. Winds will turn out
of the southwest along/behind the boundary, which will combine with
breaks in the clouds to allow temperatures to recover into the lower
70s, particularly over south-central and southwestern zones where
morning precip will vacate sooner. Convergence along the boundary,
augmented by lingering upper level divergence, will likely provide
sufficient lift for at least isolated redevelopment of showers &
storms within this air mass on Tuesday afternoon. Given a plume of
steep (7-8.5 degC/km) mid-level lapse rates moving in from the west,
said redevelopment would occur in an environment conditionally
favorable for large hail. Well-mixed boundary layers depicted in
forecast soundings would support some potential for gusty winds as
well. Thus can`t rule out a few strong to severe storms tomorrow
afternoon. SPC has extended a marginal (level 1/5) risk for severe
thunderstorms into the region given this potential.


Quigley

&&

.LONG TERM...
Issued 409 AM CDT Mon May 6 2024

Tuesday night through Sunday:

Synopsis: Developing in the lee of the Rockies during the end of the
short term period, an area of low pressure will migrate into the mid-
Mississippi Valley on Wednesday, ultimately passing from Central IL
to the Lake Erie vicinity Wednesday night into Thursday morning.
Beneath a still unsettled upper pattern linked to the current
disturbance over the Four Corners, the approach of the surface low
will support additional periods of showers and thunderstorms across
the region from Wednesday afternoon through Thursday. An isolated
strong to severe storm can`t be ruled out Wednesday
afternoon/evening, particularly over southwestern and south-central
Wisconsin. Winds will turn out of the north-northwest through the
second half of the week as the aforementioned surface low vacates to
the northeastern CONUS, bringing modestly cooler high temperatures
from Thursday through the weekend. Mirroring the surface pattern,
northwest flow will prevail in the mid-upper levels through the
second half of this week into the weekend. Encouraged by
perturbations meandering through the aforementioned upper flow
pattern, additional periods of showers and isolated thunderstorms
are possible Saturday and Sunday.

Wednesday: Encouraged by the approach of the surface low highlighted
above, as well as lingering shortwaves pivoting overhead, additional
showers and thunderstorms are expected to develop during the
afternoon and early evening hours. While the surface low is
currently forecast to remain to our south, elevated WAA ongoing
north of the low will support increasing MUCAPE across the region,
with the greatest readings currently progged near the state line in
current guidance. Thus expect convective development to be elevated
in nature, though mid-level lapse rates in the 7-7.5 degC/km range
would support some hail potential in any storms developing during
the afternoon and early evening hours, with the greatest risk
focusing where elevated instability is maximized. Will monitor
trends closely over the coming forecast cycles, as subtle changes in
the track of the approaching surface low will carry appreciable
implications on the local thermo & related storm potential.

Thursday: Additional periods of showers and storms are possible.
Don`t expect severe weather in any of this activity at this time,
but will monitor trends.


Quigley

&&

.AVIATION...
Issued 409 AM CDT Mon May 6 2024

VFR conditions are forecast through the period at all terminals. The
current deck of SCT-BKN upper cloud coverage will pivot east into
the Ohio Valley this morning, giving way to mostly clear skies
through the daytime hours today. Winds will gradually pivot out of
the east-southeast this afternoon as low pressure begins to develop
in the Northern Plains. Speeds will increase moving into the
overnight hours as the aforementioned low continues to strengthen.
Can`t rule out LLWS between the 2500-5000 feet AGL layer during the
overnight hours, particularly at the Lake Michigan aerodromes,
though confidence was too low to justify inclusion in the 06/09Z
updates. Will monitor trends over the coming cycles and make
amendments if confidence increases.

Quigley

&&

.MARINE...
Issued 409 AM CDT Mon May 6 2024

Currently light and variable surface flow will begin to increase out
of the east today, ultimately shifting out of the southeast from
tonight through Tuesday morning as a 982 mb low pressure center
develops over the northern Great Plains. An area of showers and
embedded thunderstorms will approach from the west Tuesday morning,
ultimately crossing the open waters during the afternoon hours. Said
activity is not currently anticipated to be strong/severe.
Additional shower and storm activity can`t be ruled out on Tuesday
evening, though coverage will be more scattered compared to the
afternoon round of activity. Any storms developing Tuesday evening
would be capable of gusty winds and hail. Winds will turn out of the
southwest Tuesday night as a 998 mb low pressure center moves from
the open waters toward Lake Huron, prior to turning out of the
northeast on Wednesday afternoon as a second area of 998 mb low
pressure approaches from the central Great Plains. Additional
showers and thunderstorms are possible as the second area of low
pressure approaches. Winds will turn out of the north through the
end of the week as high pressure builds into the Great Plains.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645...7 AM Tuesday to
     7 PM Tuesday.

&&

$$

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