439
FXUS63 KMKX 120911
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
411 AM CDT Mon Aug 12 2024

.KEY MESSAGES...

- Low chances (15 to 20%) of showers and possibly a thunderstorm
  across east central WI this afternoon.

- Dry conditions are expected Tuesday and Wednesday as high
  pressure influences the region.

- Chances for showers and thunderstorms (30 to 70%) from
  Wednesday night into this weekend. Highest chances (60 to 70%)
  for rainfall are Thursday / Thursday night.

&&

.SHORT TERM...
Issued 406 AM CDT Mon Aug 12 2024

Today through Tuesday:

A weak upper shortwave trough currently over Iowa as seen in
water vapor imagery and associated shower/thunderstorm
development is expected to stay to our southwest and south as
they move through the region. However, upper level cloudiness is
expected to continue streaming across southern Wisconsin as
these features propagate eastward. Otherwise, dry conditions are
expected across southern Wisconsin through much of the day.

At 500hPa, Wisconsin is sandwiched between an area of low
pressure across the northeastern United States and the ridge
building across the central United States. Jet streaks
associated with these features remain to our east and south as
seen in the observed upper air analysis which will put northern
and east central Wisconsin in an area of speed divergence and
lower heights aloft come this afternoon. A lake breeze is also
expected to develop this afternoon under partly cloudy skies
which will promote surface convergence along the lakeshore. As
such, there is a chance (15-20%) for shower development this
afternoon across east central Wisconsin. Expecting anything that
develops to primarily be showers, but can`t rule out a rumble
of thunder given a few hundred J/kg of CAPE as seen in model
soundings and convective cloud depths reaching above
-10C. High temps today will be in the upper 70s, with a few
 locations potentially breaking 80F.

Upper level ridging then builds back into the area Tuesday with dry
air throughout the column. Deterministic global models suggest
additional precipitation development on Tuesday, mainly along
the Lake Michigan shoreline, but currently thinking that ample
subsidence associated with the upper ridge and surface high
pressure combined with the dry air will not be conducive to
said development and have kept the forecast dry on Tuesday.

Falkinham

&&

.LONG TERM...
Issued 406 AM CDT Mon Aug 12 2024

Tuesday night through Sunday:

Dry conditions are expected to remain Tuesday night through
Wedensday as the upper ridge and surface high pressure continue
to dominate the Midwest region.

A 500hPa trough ejects off the Rockies Wednesday afternoon,
supporting the development of a surface low pressure center
across the Great Plains which will lift northeastward and move
through the Midwest Thursday and Friday. Showers and
thunderstorms are expected to develop in association with this
feature as WAA, 850-700 frontogenesis, and the nose of a low
level jet move towards southern Wisconsin. Models appear to be
in better agreement as far as timing goes, so chances have been
bumped up slightly (60 to 70%) for showers and storms Thursday
morning, although the location of heaviest rainfall is a
challenge. The low will move through Wisconsin on Friday, but
moisture on the backside of the low provides additional
precipitation chances through the weekend.

Falkinham

&&

.AVIATION...
Issued 406 AM CDT Mon Aug 12 2024

VFR conditions are expected throughout the TAF period. Mid to
high clouds will continue streaming across southern Wisconsin
this morning as ongoing showers and storms across Iowa move
eastward. Diurnal cumulus around 5kft is expected to develop
this afternoon with light winds out of the west. A lake breeze
is also expected this afternoon which will shift winds at the
lakeshore sites to an easterly direction. There is a 15-20%
chance of showers across east central Wisconsin this afternoon
with SBM being the most likely to see any precipitation, but
can`t rule out a rumble of thunder. Otherwise the forecast
remains dry today.

Falkinham

&&

.MARINE...
Issued 406 AM CDT Mon Aug 12 2024

High pressure of 30.1 inches centered over Illinois this morning will
continue to move eastward Monday and Tuesday allowing for lighter
and more variable winds. Winds will become east to southeasterly
and accelerate on Wednesday as low pressure of 29.7 inches
develops across the Central Plains and moves towards lifts
northeast towards the Great Lakes, moving through the region on
Thursday and Friday. Shower and thunderstorm chances exist across
Lake Michigan on Thursday and Friday due to this low.

Falkinham

&&

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

$$

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