242
FXUS63 KMKX 091423
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
923 AM CDT Thu May 9 2024

.KEY MESSAGES...

- Areas of rain are ongoing and will continue into the mid
  afternoon before gradually tapering off. Main chances for
  lightning would be in the southwestern half of the state this
  afternoon but anything that develops will stay below
  strong/severe levels.

- Winds and waves will approach but stop short of Small Craft
  Advisory criteria this afternoon. Trends will be monitored to
  see if conditions reach criteria and warrant an Advisory.

- Periods of showers and a few rumbles of thunder are expected
  Friday evening through Saturday. Strong storms are not
  expected at this time.

&&

.UPDATE...
Issued 923 AM CDT Thu May 9 2024

Rain has moved into southern Wisconsin along and north of an
inverted surface trough that extends from a low centered over
southeast Illinois. Expect that light rain will through much of
the morning and early afternoon as a pivot happens with the
inverted surface trough due to a cold front also dropping south
across the state. 09.13z RAP shows a few hundred J/kg of SBCAPE
developing in the southwest part of the state this afternoon, so
some lightning is possible there, but not likely. Thermal/wind
shear profiles from the RAP certainly don`t suggest anything
strong/severe occurring.

Halbach

&&

.SHORT TERM...
Issued 416 AM CDT Thu May 9 2024

Today through Friday:

WAA from the TROWAL region of a low pressure passing to our
south over IL/IN will continue to spur shower activity through
the rest of this morning into the mid afternoon. By the mid
afternoon, most of this WAA should pivot south and east, and
CAA should kick in aloft. The CAA may be enough to sustain some
scattered light instability driven showers into the early
evening. Weak sfc ridging should then move in overnight
promoting subsidence and the clearing of skies overnight and
through most of Friday. Clouds will then increase late Friday
afternoon as a weak shortwave and sfc low bring an area of
showers and thunder southeast from MN toward southern WI.

Temperatures overall today should be limited by the cloud cover
and rain limiting highs to the upper 50s to low 60s.
Temperatures then rebound on Friday to the mid to upper 60s.

CMiller

&&

.LONG TERM...
Issued 438 AM CDT Thu May 9 2024

Friday night through Wednesday:

A weak surface low and shortwave is expected to bring shower and
storm activity Friday night into early Saturday morning for
most of southern WI. The main wave/sfc low should exit southeast
by dawn on Saturday, and skies should clear. This will promote
sufficient daytime heating and with cold air aloft from a larger
500mb trough positioned over Lake Superior/Southern Canada, we
may hit the covective temperatures and get instability driven
showers Saturday afternoon. PoPs for this are low at the moment
(~30% from 18z Sat to 00z Sun), so any activity that forms
Saturday afternoon isn`t anticipated to be a washout at this
time.

A weak sfc ridge will then pass over the area Saturday night
into Sunday, ahead of a weak sfc trough that will sink southeast
Sunday evening, bring more nebulous chances for rain/rumbles of
thunder Sunday night.

Long range models then grow fuzzy in their evolution beyond
Sunday night, with the NBM painting broad PoPs of 20 to 35% over
the upper Great Lakes region through most of the rest of the
extended. Aloft, flow grows more zonal with multiple waves
propagating from west to east leading to on and off rain chances
into mid week. None of this activity looks like it will be
severe however. We will suffer from a lack of deep moisture
from the Gulf of Mexico as the subtropical jet is expected to
blow up multiple thunderstorm complexes through the Gulf States
this upcoming week, blocking good sfc return flow and flow
aloft looks weak, keeping shear low.

CMiller

&&

.AVIATION...
Issued 923 AM CDT Thu May 9 2024

Main concern/challenge will be with when sites hit MVFR
conditions either for visibility dropping to 5sm or for ceilings
dropping to 1-2kft. It`ll be a bit random through the day but
will be more likely this morning and early afternoon as a band
of rain moves through the southern part of the state. Conditions
should improve into tonight as drier air moves in behind a cold
front. Another round of rain showers/potential storms moving
through tomorrow afternoon/evening along another cold front
could bring the next round of potential brief storms in.

Halbach

&&

.MARINE...
Issued 401 AM CDT Thu May 9 2024

Low pressure will be replaced by weak high pressure of 29.9
inches over Lake Michigan later today and into tonight. There
should be extensive cloud cover over most of the lake, save for
the north end, with areas of light rain mainly over the southern
half of the lake during this time. Gusty north to northeast winds
to around 20 knots, with occasional higher gusts, will occur over
the lake, mainly late this morning into the evening.

Locally, these gusts will approach small craft advisory
criteria for a brief period this afternoon, but fall short of
needing an advisory issuance. Nonetheless, we will monitor winds
and waves to see if conditions come in stronger than forecast
and warrant an advisory. Gusts should then taper off tonight.

Friday should be dry before the next low pressure system moves
into the Great Lakes Friday night with increasing winds and
another chance for rain.

CMiller

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...noon
     Thursday to 10 PM Thursday.

&&

$$

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