006
FXUS63 KMKX 071537
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1037 AM CDT Tue May 7 2024

.KEY MESSAGES...

- Showers and thunderstorms continue this morning. Additional
  showers and thunderstorms will redevelop this afternoon and
  evening, a few of which could be strong to severe.

- Small craft conditions are expected today.

- Showers and thunderstorms are possible Wednesday afternoon
  through Thursday.


&&

.UPDATE...
Issued 1037 AM CDT Tue May 7 2024

The initial line of showers and storms moving northeast this
morning will continue its trek through Wisconsin. Upper level
lift and support from the trough centered over the northern
Plains will create enough synoptic support to prevent any
subsidence on the back side of this line of storms. What this
means is that there will be cloud cover that continue to linger
throughout the day. Filtered sunlight to very brief breaks in
the cloud cover will be the most southern Wisconsin should get.
This will limit the environmental recover a bit for this
afternoon. Warm moist air advection will aid in temperatures and
dewpoints climbing again boosting low level instability. The
main concerns for redevelopment along the warm/occluded front
this afternoon will be hail. Mid level lapse rates continue to
look impressive around 7-8 C/km which will aid in the hail
development. Still cant rule out a brief spin up, but the best
chances for any tornadic activity will be right along the warm
front. Low level Storm Relative Helicity and soundings in
general aren`t very supportive of spinning, but the warm front
will provide a wind direction shift that could be just enough.
Regardless chances are low and anything that does develop will
be brief.

Patterson

&&

.SHORT TERM...
Issued 410 AM CDT Tue May 7 2024

Today through Wednesday:

Synopsis/Mesoanalysis: GOES water vapor imagery places a nearly
stationary upper low over the MT-ND-SD border vicinity early this
morning. Positioned between the Northern Plains upper low and
shortwave ridging over the Western Great Lakes, a diffluent upper
flow pattern is evident over the Upper Mississippi Valley. At the
surface, a now occluded surface low has been analyzed over western
ND, with an occluded front being drawn southeast toward St. Cloud,
MN. A cold front extends southwest from this region into the Central
Plains, with a warm front apparent from the Twin Cities into the
Wisconsin River Valley. Encouraged by a combination of the
aforementioned features, a line of showers and storms is in progress
over east-central IA, and is expected to track across the region
near and after sunrise today as it slowly weakens. Said activity
will push east over Lake Michigan by late-morning/early afternoon,
allowing the warm front highlighted previously to advance northeast
into the state. Additional shower and thunderstorm development is
anticipated during the afternoon and evening hours as temperatures
climb into the upper 60s and low 70s in the wake of the boundary.
Severe weather is possible in this activity. Redeveloped showers and
storms will push east over Lake Michigan tonight, giving way to dry
conditions through the first half of Wednesday. A secondary area of
low pressure will approach from Iowa on Wednesday afternoon,
ultimately passing south of the region. Scattered shower and
thunderstorm chances will increase once more ahead of this feature
Wednesday afternoon, with the best chances holding off until
Wednesday night & the beginning of the long term period.

This Morning: Expect the ongoing shower/storm activity over IA to
hold together and push east across the region. Earlier CAM guidance
suggested that this activity would be well into its weakening phase
while crossing the area, and while this expectation generally
remains on track, convection has been able to maintain itself at
levels not progged in the aforementioned set of earlier CAM
solutions. Said trends have been noted observationally over the last
several hours, with jumps in lightning activity and cooling cloud
tops continuing to occur in satellite imagery. A combination of
lingering MUCAPE and sufficient shear is likely behind the
persistence of convection at strong to marginally severe levels, and
while activity will encounter decreasing shear as it moves into
southern Wisconsin after sunrise, guidance does show several hundred
J/kg of MUCAPE over the region as storms move through. Will thus
need to monitor trends for an isolated stronger storm with small
hail/gusty winds as activity pushes in, though the aforementioned
weakening shear and stable boundary layer conditions should preclude
a greater risk from materializing.

This Afternoon & Evening: With early morning activity pushing east
over Lake Michigan, winds will turn out of the southwest across the
region as the warm front discussed in the synopsis advances north.
The wind shift/related warm advection -- combined with any breaks in
the clouds behind the departing showers & storms -- will allow
temperatures to climb into the upper 60s and low 70s away from Lake
Michigan. Said surface heating, combined with lift along the front &
lingering diffluence aloft, will support scattered redevelopment of
showers and storms across the region this afternoon and evening.
These storms will be forming as an area of colder temperatures
aloft/steep mid-level lapse rates overspread the region. Combined
with sufficient effective shear ranging between 25-35 kt, the
potential for large hail will thus exist in any redeveloping storms
this afternoon. Isolated damaging wind gusts will also be possible
given dew point depressions in the boundary layer. While far and
away secondary to the hail & damaging wind potential, a brief spin
up can`t be ruled out, particularly in locations positioned near the
warm front where winds will back out of the southeast & low level
shear will be enhanced. Be sure to have multiple ways to receive
warnings this afternoon & evening. Severe potential will taper by
mid-evening as activity pushes east over Lake Michigan.

Quigley

&&

.LONG TERM...
Issued 410 AM CDT Tue May 7 2024

Wednesday night through Monday:

While a marginal risk is painted over far southwest Wisconsin
through the overnight hours Wednesday night into Thursday, it
currently looks like it`ll be difficult for us to realize a severe
threat owing to a couple of factors. First, a trough attached to
an area of low pressure over Lake Ontario will sink south over
Wisconsin late in the afternoon. This will drive cool northeast
flow off of the lake and cause a strong inversion that could push
as far inland as Madison. Second, more favorable flow and PVA
from a compact 500mb cutoff low will be focused south of the
state, and favorable return flow of moisture from the Ohio River
Valley will be blocked by an early day MCS. We`ll still realize
precipitation over our area Wednesday night into Thursday owing to
some weak 850 to 700mb WAA in escutcheon with a TROWAL over the
area, but the precip will be stratiform to shower in nature.
There will be pockets of CAPE aloft, ranging from 250 to 500
J/kg, so a rumble of thunder can`t be ruled out with this
activity.

Rain should linger into Thursday afternoon before tapering off as
the TROWAL shifts east. Conditions dry for Friday with a mix of
sun and clouds as a weak surface ridge shifts southeast over the
state. Rain chances then return Friday night as a weak shortwave
sinks southeast across the state. This shortwave should drive the
formation of a weak sfc low that will meander southeast over
southern Wisconsin through Saturday, causing areas of showers.
High pressure and better weather then takes over by Sunday.

CMiller

&&

.AVIATION...
Issued 1037 AM CDT Tue May 7 2024

MVFR to LIFR conditions are expected today across southern
Wisconsin through this evening. As the line of
showers/thunderstorms moves northeast through the area this
morning, ceilings around 2 kft to 500 ft will be possible with
visibilities ranging from 2-6 SM. Behind this line of storms,
ceilings of 2-5kft will persist through the afternoon. The cloud
deck is expected to be scattered to broken during this time.
Once the rain ends, visibilites will improve back toward 10 SM.
Additional rain/storms will develop this afternoon and early
evening bringing another round of lower IFR to LIFR ceilings and
visibilites. Strong to severe storms will be possible this
afternoon/evening. Tonight VFR conditions will return as skies
briefly clear.

East to southeast winds this morning will become southwesterly
by late this evening behind the occluded front. Overnight winds
become lighter and variable, eventually becoming easterly again
by Wednesday afternoon.

Patterson

&&

.MARINE...
Issued 410 AM CDT Tue May 7 2024

Breezy east to southeast winds will prevail over the open waters
today as a 986 mb low pressure lingers over the northern Great
Plains. Periods of showers and embedded thunderstorms will be
possible from late this morning through this evening. A few of these
storms could be strong with gusty winds and hail, particularly later
this afternoon and early this evening. Winds will turn out of the
northeast over the lake on Wednesday afternoon and evening as a
second area of 1000 mb low pressure passes south and southeast of
the open waters.  Additional periods of showers and thunderstorms
are possible from Wednesday evening through Thursday, with
conditions drying out Thursday night. Northerly winds will persist
through Friday morning, prior to turning out of the southwest on
Friday afternoon as a 1005 mb low pressure moves across Ontario.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 7 PM
     Tuesday.

&&

$$

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