413
FXUS63 KMKX 190236 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
936 PM CDT Sat May 18 2024

.KEY MESSAGES...

- Isolated thunderstorms this evening, especially northwest of
  Madison. Gusty winds possible.

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

- Increased risk for strong/severe storms Tuesday and Tuesday
  evening.

&&

.UPDATE...
Issued 936 PM CDT Sat May 18 2024

The incoming cold front has struggled to produce much in the
way of showers/storms so far this evening. Isolated activity has
pulsed up and down toward the Dells, with better sustained
updrafts in/around Waupaca.

There will remain enough convergence to maintain a risk of
isolated showers and storms into the early overnight hours,
mainly north the I-94 corridor. Loss of daytime heating has
resulted in waning instability and an increasing cap. As a
result any storms that are able to develop will be capable of
lightning, small hail and perhaps a few wind gusts, though the
opportunity for any gusts would be in the next hour or two.

Light southwest winds ahead of the front have allowed
temperatures to stay rather warm so far this evening. The
forecast has been adjusted for a slower temperature descent,
though lows in the 50s continue to look good by daybreak Sunday.
Enjoy the quiet, warm day Sunday as the pattern will once again
becoming active Monday and Tuesday.

Gagan

&&

.SHORT TERM...
Issued 237 PM CDT Sat May 18 2024

Rest of this Afternoon through Sunday:

Temperatures have warmed into the 80s inland (70s lakeside)
this afternoon, under abundant sunshine. Deep mixing has
resulted in dewpoints dropping into the 50s and low 60s in many
locations, with just a few high based cu.

The main focus this evening will be on a cold front currently
located to our northwest. This front and an associated pre-
frontal trough will push into south central Wisconsin early
this evening. Overall upper level support is weak, with the main
shortwave moving across western Lake Superior. This, along with
the deep mixing and dry boundary layer, will probably limit
convective coverage along the front. That said, the dry and well
mixed boundary layer will also present a threat for strong wind
gusts for any organized convection that does form, given the
inverted v profile.

Convective coverage will decrease fairly quickly through the
evening, with just a handful of showers/storms (if that) by the
time the front reaches southeastern Wisconsin late this evening.
Skies will clear overnight, with lows in the 50s.

High pressure makes a brief appearance tomorrow, with light and
variable winds and highs in the upper 70s to near 80. With the
light wind profile, expect a well-developed lake breeze to move
inland during the afternoon hours.

Boxell

&&

.LONG TERM...
Issued 237 PM CDT Sat May 18 2024

Sunday Night through Saturday:

Scattered showers and storms will develop overnight Sunday
night into Monday morning as a strong low level jet noses into
the area. Hail will be possible with a few of the strongest
storms.

Additional thunderstorms are possible during the day Monday,
depending on the timing of a shortwave moving through the area.
If the wave moves through during the morning as currently
expected, there may be enough capping/subsidence in the
afternoon to limit additional precipitation. However, a slower
progression would favor more convective development in the
afternoon, including the potential for a few stronger storms.

Tuesday continues to look like our best chance for severe
weather, though the situation remains somewhat messy and
complex. Low pressure lifting through western Iowa and southern
Minnesota is expected to reach western Wisconsin by afternoon
and evening, with an associated warm front lifting northward
through the region. Convection will likely be ongoing north of
this front Monday night and Tuesday morning, but there may be
enough capping south of the warm front for a break early Tuesday
afternoon. The current scenario suggests that severe
thunderstorms may then develop over Iowa and northern Missouri
Tuesday afternoon, and move east-northeastward Tuesday evening
ahead of an advancing cold front. All modes of severe weather
will be possible, though the wind and spin-up tornado threat
will be greatest if convection is able to congeal into an
organized convective complex by the time it reaches southern
Wisconsin.

Ultimately, the location of the warm front and degree of
instability that is able to develop Tuesday and Tuesday
afternoon will be very key to the eventual severe weather
threats.

Drier air looks to then build into the region mid week as high
pressure moves through the area, with southerly flow returning
late in the week/early next weekend.

Boxell

&&

.AVIATION...
Issued 936 PM CDT Sat May 18 2024

Showers and storms have remain rather isolated in coverage
(north and west of MSN) with the best coverage toward central
and northern WI. The incoming cold front will shift winds from
southwest this evening to northwest overnight, however
confidence is low that a shower or storm will affect any of the
area aerodromes and any mention in the TAFs will be removed with
a forthcoming update.

Winds will continue to shift on Sunday, with easterly winds
setting up during the afternoon. Aside from a few passing high
clouds, VFR conditions are expected into Sunday evening.

Gagan

&&

.MARINE...
Issued 237 PM CDT Sat May 18 2024

Southwest winds will continue this afternoon and early evening ahead
of a cold front. Winds become northerly early Sunday behind the front,
before becoming light and variable as high pressure moves
through Sunday afternoon. Breezy southerly winds return Monday
and Tuesday ahead of the next approaching low pressure
system. Small Craft Advisories are likely to be needed during
this time.

Boxell

&&

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

$$

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