889
FXUS63 KMKX 241738
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1238 PM CDT Fri May 24 2024

.KEY MESSAGES...

- Another round of strong to severe thunderstorms will be
  possible this afternoon and early evening, but the extent of
  it should be limited by persistent cloud cover and ongoing
  precipitation.

- Keeping an eye on another round of thunderstorms on Sunday,
  but the more favorable environment remains just south of
  southern WI at this time.


&&

.UPDATE...
Issued 1237 PM CDT Fri May 24 2024

Persistent low to mid level warm, moist advection is producing
showers and storms over ern IA into sw WI. This is expected to
continue until the cold frontal passage early this evening.
Initially these storms will remain elevated due to large MLCIN
in the wake of the ongoing showers and storms, but a sly LLJ of
30-40 kts will maintain warm advection and moisture transport
with MLCAPE possibly recovering to 1000-1500 J/KG. The MLCIN may
reduce to 25-50 J/KG by late afternoon and early evening so sfc
based convection will be possible. Thus a severe threat remains
given effective shear of 30-40 kts and effective SRH of 150-200
m2/s2. All hazards will be possible but the extent of severe
should be limited by the aforementioned CIN and somewhat poor
low level lapse rates.

Gehring

&&

.SHORT TERM...
Issued 354 AM  CDT Fri May 24 2024

Today through Saturday:

Another active pattern is in store for southern WI today as a
mid- level trough and accompanying surface low pivot
northeastward across the Upper Midwest. This is looking to bring
multiple rounds of thunderstorms and each bringing a potential
for stronger to severe weather.

The first round will be this morning as an ongoing line of
severe thunderstorms currently making its way across the
Missouri River Valley along the NE/IA border is progged to lift
into southern WI. The big question with this activity is will it
maintain its strength as it tracks eastward early this morning.
Current it anchored to the instability axis aligning with the
effective shear zone and LLJ. While SPC mesoanalysis shows CIN
associated with the upstream SBCAPE >1000 J/kg , these showers
seems to be overcoming the CAP at this time. Given the trends
along with some developing convection out ahead of it along the
effective warm frontal boundary, thinking there is a pretty good
chance we will see this line make it into our neck of the woods
later this morning as the instability axis lifts northeastward
along with the LLJ persisting.

Most of the 00z and later CAMs indicate seeing the line make it
up here between 12z-14z for our western CWA, but handle this
MCS evolution differently. While the the 00z-04z runs of the
HRRR seem to be the more aggressive solutions with this line
maintaining it strength as it traversing into southwestern WI.
Given the latest trends, is not looking unplausible as long as
it does outpace the instability. However, most CAMs including
the NSSL-WRF, ARW, and NAM- Nest, weakening the line, especially
as the deep layer shear seems to weaken a bit through the
morning. The latest 06z seems to be jumping onboard more to this
scenario as well. Nevertheless will need to monitor trends as
it may have a narrow window as it pushes into the area where it
may be strong-severe bringing gusty winds and maybe some hail
and with it riding the warm frontal boundary, cannot rule out
seeing an embedded QLCS tornado or two with this round,
especially with 00z HREF progged 0-1km SRH around 100-150 m2/s2.
The better potential for this round of strong-severe storms
will be mainly south and west of Madison as the line is progged
to weakens as it pushes east.

After the morning round of storms, there looks to be a lull for
a couple of hours. Then thunderstorm redevelops and activity
picks back up as the upper-level trough swings through as the
cold front slides across the area. Given the lull and the warm
front progged to lift at least into the east-central WI, the
environment looks to recovery enough for the next round of
development where MUCAPE creeps to around 1000-1500 J/kg and
0-3km SRH exceeds 200 m2/s2. Given the upper-level dynamics,
forcing, and mesoscale setup, all severe hazards will be
possible with this second round as it develops just upstream or
overhead and congeals into a line as it tracks eastward.

However, there continues to be some uncertainties with the
afternoon/evening round, one of the main point being how does
the first round impact the environment and will there be enough
recovery between the morning and afternoon/evening round.
Another concern is timing as some models like the HRRR are
faster in the progression of this storm activity with the other
CAMs are a bit slower. Also there are even a solution or two
such as the 00z ARW where the afternoon round does not develop
likely a result of the lack of recovery behind the morning round
and/or the warm front stalling further south. While these are
the minority of solutions, there is still a low end potential to
see this scenario play out. Otherwise, will lean more on the
majority of the hi-res model guidances and bank on afternoon
redevelopment with another round of strong to severe
thunderstorms mainly after 21z through 03z before the cold front
slides through.

Once the cold front pushes through, expect high pressure to
build in behind and dry/cool things off for Saturday.

Wagner

&&

.LONG TERM...
Issued 354 AM CDT Fri May 24 2024

Saturday night through Thursday:

Saturday night looks fairly quiet as a weak surface high
gradually pushes off to the east as a fairly strong low pushes
in from the southwest. Sunday morning we will start to see this
system push in which will be associated with a fairly strong
shortwave aloft. This system will also be heavily influenced by
40-60kt LLJ sliding through the CWA during the day. The severe
potential Sunday afternoon exists primarily due to the LLJ and
the strong 0-3km helicity and deep layer shear associated with
it.

While some storms could be expected into the early afternoon
the environment may be heavily influenced based on how far north
the warm front gets in addition to just how much instability we
can muster up, especially when clouds would likely figure into
this discussion with ongoing precip/storms from the morning.
Several models suggest that much of the activity could really
begin too far east to impact the CWA but if there is any chance
it seems mostly restricted to southeast parts of the CWA. On the
flip side if things are a bit slower in terms of progression it
will open up a window for strong to severe storms with all-
hazards possible.

The deepening surface low will gradually push northwest into
the northern Great Lakes region and into Ontario but one thing
to point out Sunday night through much of Monday is that some
wrap- around precip will be possible (30-40%) due to some
shortwave energy lingering in the region along with some
moisture. In addition slight effects from the TROWAL may play a
role as well. It seems tough to gauge the likelihood of precip
given the potential being largely driven by the shortwave energy
(placement) in addition to moisture associated with the
shortwave energy.

Tuesday will also feature continued chances (20-30%) for
showers, though weak, due largely to the upper low digging
through the region. Wh and will depend on the morning round. If
  environment recovers between rounds, then could see the
  potential for near severe hail and gusty winds and even a
 brief, isolated tornado can`t be ruled out.ile there remains
lots of uncertainty with this upper closed low and its
progression from central Canada into the western Great Lakes
region the main questions will be the moisture associated with
it as it appears questionable, which is the main reason for just
chances as the forcing will not be the issue.

By midweek it appears for at least a short period we will
finally return to drier conditions with higher pressure sliding
in ahead of ridging aloft

Kuroski

&&

.AVIATION...
Issued 1237 PM CDT Fri May 24 2024

Rounds of showers and storms will continue this afternoon and
evening. Areas of MVFR Cigs and Vsbys may briefly occur in the
wake of any of the stronger storms. Areas of MVFR Cigs are also
expected for a brief time along and after the passage of the
cold front this evening. Skies will then clear during the
overnight hours with VFR conditions into Wed.

Gehring

&&

.MARINE...
Issued 354 AM CDT Fri May 24 2024

High pressure continues to push into the eastern Great Lakes
early this morning. Meanwhile light and variable winds early
this morning will turn east to southeasterly as warm front lifts
northward through the afternoon as a deepening low pressure
lifts into the Upper Midwest this evening. This will then drag a
cold front across Lake MI overnight tonight turning winds more
westerly int Saturday. Also accompanying these frontal
boundaries will be rounds of thunderstorms today, but ending
later this evening. High pressure will then move across Lake
Michigan for Saturday afternoon and evening before another low
pressure lifts across the region Sunday. Next week is likely to
start off with northwesterly winds as the low lifts out of the
Upper Great Lakes region.

Wagner

&&

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

$$

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