000
FXUS63 KMKX 110913
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
413 AM CDT Thu Apr 11 2024

.KEY MESSAGES...

- Low pressure shifted further east resulting in lower rainfall
  amounts, generally less than half an inch today. But still
  expecting showers and a few thunderstorms, especially for
  areas west of a line from Fond du Lac to Janesville, this
  afternoon. Any heavier shower or thunderstorm may bring
  locally higher rainfall.

- River flooding will continue through the weekend on isolated
  portions of the Lower Fox and Rock Rivers.

- Gusty northwest winds are expected through most of Friday,
  with a gales possible over the open waters.

- Above normal temps expected for the weekend into early next
  week.

&&

.SHORT TERM...
Issued 405 AM CDT Thu Apr 11 2024

Today through Friday:

The latest radar imagery shows a thin, broken band of
sprinkles/light rain working its way across western WI this
morning along a weak cold frontal boundary. Upstream obs only
show a trace of accumulations associated with this activity,
thus have sprinkles mentions through the morning as this
boundary pushes through the area.

Otherwise, there has been a shift in the forecast compared to
24 hours ago. The 00z ECMWF and GFS now show the upper-level
trough phasing later, thus the surface low continues to deepen
and lift later and further east. As a result of this shift and
delay, our shower chances have followed suite. The area of
showers associated with the southern upper-level trough looks to
now stay far enough east to limit PoPs chances and rainfall
amounts in the eastern CWA this morning. But it would not be out
of the question for the lakeshore to be clipped by the western
edge of the precip shield. It now looks like our better shower
chances will be with the northern trough as it swings across the
Upper Midwest through the day. Hi-res models still pick up on a
northerly to southerly orientated band of broken showers to
develop this afternoon and work their way east through the
evening along the mid-level vorticity max.

Given the delay in phasing and precip, this will allow for
temps to warm a bit more into the upper 50s and lower 60s this
afternoon and result in a bit of instability to build up
through the morning, especially across the western half of the
CWA. Most models and the 00z HREF only show minimal values with
MUCAPE <500 J/kg. Nevertheless, should be enough for a few
embedded thunderstorms with the afternoon shower activities.
While cannot rule out some small hail from any of this
thunderstorm activity given modest mid-level lapse rates around
7 C/km, most of it should remain sub-severe given low
instability and minimal deep layer shear (<45kt). Again given
the shift, precip amounts have lowered quite a bit as well.
Generally looking at less than half an inch across the area, but
could see a few isolated pockets of locally higher amounts that
may occur with any deeper showers or thunderstorms that may
develop.

Otherwise, shower chances will diminish through the evening as
the upper-level trough phases and the surface low deepens over
the eastern Great Lake Region overnight. Still expecting a tight
pressure gradient to setup across the region for Friday and
gusty winds are expected. Could see gusts around 25-35 mph
Friday afternoon, but higher potential has shifted east as well.
Friday looks to be mild as well with high temps closer to
normal in the 50s.

Wagner

&&

.LONG TERM...
Issued 405 AM CDT Thu Apr 11 2024

Friday night through Wednesday:

Quite, warming weather generally prevails through the weekend,
although a quick-hitting shortwave may produce a few showers
and perhaps an isolated thunderstorm Saturday night, especially
in central Wisconsin. Northwesterly breezes behind this
shortwave will temper high temperatures on Sunday, but still
expecting highs nearing and exceeding 70 degrees if timing of
the shortwave remains consistent. If this shortwave slows down,
cloud cover would keep temperatures lower. Monday, stiff WAA
increases cloud cover ahead of a developing low pressure system
in the central Great Plains, leading to high temperatures in
the 70s once again.

WAA continues through Tuesday, with increasing instability
ahead of the longwave trough ejecting from the central Plains
northeastward. Current modeling implies 500 mb trough tilting
neutral to negative relative to the mean flow on Tuesday, which
may lead to concerns about storm development. That being said,
ECMWF takes a low track through southern Wisconsin while the GFS
swings the low northward into northern Minnesota. Plenty of
variability in low track remains in ensembles as well, with
trends towards the western half of the state seeing the best
chances for thunderstorm activity. The primary low lifts
northward into Ontario into Wednesday, with chances for
additional precipitation lingering along an extended cold
front.

MH

&&

.AVIATION...
Issued 405 AM CDT Thu Apr 11 2024

VFR conditions persist this morning with mid to high cloud
cover. winds will remain light through daybreak, but will pick
up and shift more north-northwest as a weak cold front slides
across the region. Showers chances continue to trend later and
outside of a stray sprinkle, this morning will remain mostly
dry. Then shower chances pickup through the afternoon as a
broken band works its way west to east across southern WI. Could
see a few thunderstorms west of a line from Fond du Lac to
Janesville later this afternoon and evening before diminishing
tonight. Can expect to see lower, mainly MVFR levels, flight
conditions accompany the shower and thunderstorm activity, but
IFR will be possible if under a heavier shower/thunderstorm.
Additionally northwesterly winds will pick up with this
activity as well. Shower chances diminish later tonight, but
gusty conditions will continue into the day Friday.

Wagner

&&

.MARINE...
Issued 405 AM CDT Thu Apr 11 2024

A bit of tricky forecast for winds over the Lake Michigan later
today into Friday. Continue to see a trend delaying the
stronger wind gusts later into early Friday morning now as the
surface low deepens further east than previous forecast. There
continues to be gale potential as this low deepens and lifts
across the eastern Great Lakes, but some questions remain. Have
higher confidence in seeing northwesterly gale force gusts
across the northern third of Lake Michigan and have upgraded to
a Gale Warning for early Friday morning through Friday
afternoon. However, will maintain and have delayed the start of
he Gale Watch for the southern two-thirds given the easterly
shift of the surface low. Also while the strong winds are
present aloft, it still remains to be seen if they can overcome
the stable layer and mix down. Nevertheless, the more favorable
locations for gales in the south two-thirds of the lake is over
the eastern side of the open waters and lower MI lakeshore.

Winds will gradually weaken later Friday night into the weekend
as the low tracks northeast into Quebec. Then broad area of
high pressure will fill in behind this system for Saturday
before a weak area of low pressure moves across the middle of
Lake Michigan on Sunday.

Wagner

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Warning...LMZ261-LMZ362-LMZ364-LMZ563...4 AM Friday to 7
     PM Friday.

     Small Craft Advisory...LMZ645-LMZ646...4 PM Thursday to 7 PM
     Friday.

     Small Craft Advisory...LMZ643-LMZ644...1 AM Friday to 7 PM
     Friday.

     Gale Watch...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...4 AM Friday to 7 PM Friday.

&&

$$

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