299
FXUS63 KMKX 200247
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
947 PM CDT Sun May 19 2024

.KEY MESSAGES...

- Unsettled Monday and Tuesday with several rounds of
  rain/storms.

- Risk 2 out of 5 for severe thunderstorms exists for Monday
  primarily over the southeastern corner of our CWA at this
  time. The main threats are gusty winds and hail.

- While there remains uncertainty on the exact specifics of the
  severe weather threat Tuesday, there remains a higher chance
  (risk 3 out of 5) for severe weather on Tuesday with all modes
  of severe weather (large hail, damaging winds, and tornadoes)
  possible. Overnight storms Monday into Tuesday and how they
  track/evolve over IA/IL will impact the development and
  environment Tuesday afternoon and evening.


&&

.UPDATE...
Issued 945 PM CDT Sun May 19 2024

No major changes to the current forecast. There are a few
pockets of light reflectivity making their way into the area
late this evening, however, the showers have a
downward/weakening trend. Areas west of Madison may see a brief
shower, but otherwise most of the CWA should remain mostly dry
through the first half of the night. Then our focus shifts to
the upstream showers and thunderstorm activity over southwest IA
as it looks to lift into the area by early Monday morning
bringing an initial round of showers and thunderstorms mainly
between 10z-15z.

Then we may see a brief lull before the MCV
feature currently located with the severe thunderstorms in
eastern KS lifts northeast through the early afternoon and
redevelops showers and storms, especially for our far
southeastern counties. Main concern with the afternoon activity
will be some hail and gusty to damaging winds. The latest 00z
HRRR is showing most of the morning convection limiting the
redevelopment in the afternoon for southern WI with better
chances further south and east, but other CAMs such as the 00z
ARW and NSSL-WRF still lean a bit closer to the 12z runs.
Nevertheless while the 00z hi-res models still show different
scenarios on how the convection will evolve, the main driver
will be the MCV feature upstream and where it will track
overnight. So will need to monitor and see how things evolve in
the coming hours.

Wagner

&&

.SHORT TERM...
Issued 400 PM CDT Sun May 19 2024

Tonight through Monday night:

High pressure should keep things quiet this evening as high
clouds stream in from the southwest. With time overnight,
scattered shower and storm activity is expected to increase as
low to mid level WAA increases over our region. Activity should
congeal into a coherent blob and move east over our area around
daybreak on Monday. By midday Monday, a remnant MCV from
convection over KS will move through, providing an compact area
of enhanced flow and PVA aloft. The MCV will spread over the
area and steepen lapse rates, leading to SBCAPE around 1500
J/kg, and enhance effective Bulk shear to around 50 knots.
Storm relative helicity is weak, dampening the tornado threat,
but unstable and relatively dry low levels will support gusty
winds, and any transient supercellular structures should support
hail. Showers and storms should then exit after 7PM

Following the MCV, subsidence should take over, suppressing
widespread shower and storm activity, and only some very widely
scattered showers may continue overnight.

CMiller

&&

.LONG TERM...
Issued 402 PM CDT Sun May 19 2024

Tuesday through Sunday:

Tuesday`s severe weather threat appears much more robust given
the dynamics. Two waves at the 500mb level look to enhance flow
over a warm front that`s expected to surge north with time
Tuesday afternoon and evening as a sfc low deepens over Iowa
and Minnesota. NAM/GFS/ECMWF solutions depict a moist, unstable
environment with sickle hodographs, great low level instability,
effective shear of 50 knots and favorable 0-3km shear of 50
knots as well. This type of environment would support supercells
initially with upscale growth to a QLCS mode with time. Current
timing for storms appears to be in the late afternoon into the
evening. Some confounding factors appear to be the lack of jet
dynamics aloft and the positioning of the warm front. The HRRR
depicts convection exploding just south of the WI/IL border
Tuesday morning. This scenario may limit the northward
advancement of the warm front, but is an outlier for now. Once
Monday convection shows its hand and we see more runs of the
CAMs, we`ll have a better grasp of the severe threat on Tuesday.

Beyond, the weather will grow quiet Wednesday into early Friday,
before active weather returns next weekend.

CMiller

&&

.AVIATION...
Issued 945 PM CDT Sun May 19 2024

While there are a few pockets of light showers west of Madison
most of the area will see the light and variable winds and VFR
conditions overnight. Then showers and thunderstorm potential
will increase by early Monday morning as the activity in
southwesterly IA makes its way into southern WI. While there is
a pretty good chance of seeing showers especially for MSN and
JVL, there remains some question on if the initial round will
make it east toward the other southern WI terminals. Also cannot
rule a rumble of thunder or two with the morning round of
showers. Then there looks to be another window for showers and
storms across southern WI more toward the afternoon as the
thunderstorm activity in eastern KS begins to makes its way
across southern WI. While this activity looks to be scattered
and not everyone will see something, any terminals that are
impacts will likely see lower ceilings and visibility along with
gusty winds and possible some hail. This line of of showers and
storms are expected to clear east through the earl evening with
drier and VFR conditions returning.

Wagner

&&

.MARINE...
Issued 340 PM CDT Sun May 19 2024

Light and variable winds will continue over the lake through the
rest of the afternoon and evening as high pressure moves
northeast. Winds will then come around to southeasterly by
daybreak on Monday and should become more southerly by Monday
afternoon. Breezy southerly winds will remain Monday night into
Tuesday morning before winds become southeasterly ahead of a
low pressure system that will deepen as it approaches the Upper
Great Lakes Region. Periods of thunderstorms are also expected
over the lake Monday through Wednesday morning.

CMiller

&&

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

$$

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