Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 252024
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
324 PM CDT Mon Mar 25 2024

.KEY MESSAGES...

- Rainfall continues into Tuesday. Isolated thunderstorms are
  possible in far southern into southeastern Wisconsin. A
  stronger storm or two cannot be ruled out.

- Gusty southeasterly to southerly winds continue today through
  Tuesday, with gales expected on Lake Michigan tonight through
  Tuesday afternoon.

- Above normal temperatures return this weekend.

&&

.SHORT TERM...
Issued 323 PM CDT Mon Mar 25 2024

Tonight through Tuesday night:

Rain has been slow to fill in across southern Wisconsin and
surrounding areas, although patchier showers have been
developing at times. Finally seeing a steady band of rainfall
associated with upper level divergence setting up across
northern Illinois and nudging into southeastern Wisconsin. This
band is expected to wobble westward as low pressure deepens over
southern Minnesota and western Wisconsin, then sit over the
region through the overnight hours before tracking back eastward
late tonight as the low lifts toward Lake Superior.

As the main band of stratiform rainfall moves northeastward out
of the area Tuesday morning, attention turns to a low-topped
QLCS potentially pushing northeastward through far southern
Wisconsin. CAMs are indicating a dry slot feature between 11Z
and 14Z, allowing for slight destabilization that may be
enhanced if the sun is able to make a brief appearance in
southeastern Wisconsin during this time frame. The main driver
of the morning instability, however, is CAA in the 850 to 700 mb
range. This drops temperatures aloft just enough to yield
approximately 200 J/kg of CAPE ahead of a surface based trough.
Meanwhile, southerly winds around 15 kt shift to southwesterly
around 40 to 50 kt at 850 mb, yielding just enough shear and
helicity to become concerned about a low topped broken line with
an embedded rotating supercell or two. The main cold frontal
feature looks to push northeastward through the region between
16Z and 19Z, which will complete the stabilization and remove
what remains of any low-topped spinner threat.

There are still many variables that could work against this
set-up. If CAA aloft is less intense or comes into alignment
with the surface front, instability will be lacking in the low
levels. In addition, a lack of dry slot may keep surface
temperatures lower due to evaporation and lack of insolation.
The low level helicity is the strongest variable in favor of any
weak tornadogenesis, but the ability of a storm to become rooted
in the surface layer is still in question due to the morning to
midday timeframe of concern. With all concerns in mind, far
southeastern Wisconsin is the main area of concern for stronger
convective activity.

Cold frontal passage Tuesday afternoon shifts winds westerly,
with breezy conditions continuing into the overnight and
bringing in cooler temperatures. A few snowflakes may mix in as
wrap-around precipitation progresses eastward through much of
southern Wisconsin during the late evening hours. This final
round of precipitation rotates out of the region late Tuesday
night as the low lifts northeastward into Ontario. Lows in the
mid to lower 20s are expected.

MH

&&

.LONG TERM...
Issued 323 PM CDT Mon Mar 25 2024

Wednesday through Monday:

The mid-level trough that is bringing our early week active
pattern will gradually lift northeast and likely phase with
another mid- level shortwave trough over the Upper Midwest for
Wednesday. While the majority of the upper-level forcing and
moisture will be out of our area and most models and ensembles
prog southern WI to be dry and cooler. Thus, PoPs remain out, but
given the trend of slower exit as the mid-level features phase, I
would not be surprised to see a scattered flurry/light snow
showers glance our central WI counties on the backside of this
system through Wednesday morning. Overall, it is a small potential
(<15%) for anything to actually develop given thr drier airmass
and incoming subsidence with a building surface high across the
region.

Otherwise, the end of the week will remain dry as the surface
high and upper-level ridging settles over the region through
Friday. Will also see temps gradually increase each day through
the start of the weekend with a medium (40-60%) potential Thursday
and higher ((70- 90%) potential Friday for daily highs to exceed
50F.

Then the weekend looks to become more active with increasing
chances for measurable precip as system pushes across the Midwest
overnight Friday into Saturday. There is a general consensus of
low-level WAA to develop ahead of a surface feature paired with
increasing moisture (PWATS > 0.5") and will be enough to spur a
few showers. However, there continues to be a great deal
uncertainty as the long range models and ensembles differ on the
system`s timing and track due the difference in handling the
upper-level wave. Nevertheless, keep an eye on the weekend for
another chance of some spring rain with another system on the
horizon for early next week.

Wagner

&&

.AVIATION...
Issued 323 PM CDT Mon Mar 25 2024

A band of steady rainfall is pushing northward into
southeastern Wisconsin this afternoon. This band of rain is
expected to wobble westward to affect southwestern Wisconsin
late this evening, before progressing eastward once again
overnight and exiting Tuesday morning. More scattered shower
activity is expected going into Tuesday morning, with potential
for a line of weak storms progressing across far southern
Wisconsin between 12Z and 17Z, and additional shower activity
with perhaps an isolated thunderstorm along a cold frontal
feature pushing through between 17Z and 20Z. KENW is most likely
to see a thunderstorm, while KJVL and KMKE are also in the area
of potential.

LLWS is expected to continue along Lake Michigan through early
tonight as southeasterly winds increase with height. Going into
the late overnight hours and Tuesday morning, LLWS continues but
increases as southeasterly winds at the surface quickly turn to
southwesterly at 2000 ft. Winds and LLWS decrease Tuesday midday
into Tuesday afternoon as a cold frontal passes through.

Ceilings this afternoon are steadily falling from MVFR to near
1700 ft. Expect flight conditions to continue to deteriorate
overnight as rain fills into the area, dropping visibilities to
2 to 3 miles and ceilings down to IFR. Ceilings slowly rise back
to near 1500 ft Tuesday morning, continuing through Tuesday
evening.

MH

&&

.MARINE...
Issued 323 PM CDT Mon Mar 25 2024

Low pressure will lift from southern Minnesota toward Lake
Superior tonight, leading to continued gusty, southeasterly
winds at Small Craft Advisory criteria. As the low makes its
closest pass tonight, expect winds to increase to gales of 40 kt
in the open waters and in nearshore regions from Sheboygan
through North Point Lighthouse. A few gale force gusts are
possible in southern nearshore waters. Winds remain at gale
force through early Tuesday afternoon before the low lifts into
Ontario and winds shift southwestward. A Gale Warning is in
effect across the open waters and in the nearshore regions from
Sheboygan to North Point Lighthouse late tonight through Tuesday
afternoon for these concerns.

Winds shift westerly overnight Tuesday as a cold front
progresses across the lake from west to east. Small Craft
Advisory conditions are expected once again during this time.
Breezy westerly winds continue through Wednesday night into
Thursday as low pressure slowly fills in the Hudson Bay.

Rain showers are expected throughout tonight and Tuesday, with a
few thunderstorms possible across the southern half of the lake
early Tuesday morning into midday Tuesday. A few of these
thunderstorms may produce briefly gusty winds.

MH

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 3 AM
     Tuesday.

     Gale Warning...LMZ643-LMZ644...3 AM Tuesday to 1 PM Tuesday.

     Gale Warning...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
     LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...1 AM Tuesday
     to 4 PM Tuesday.

     Gale Watch...LMZ645-LMZ646...3 AM Tuesday to 4 PM Tuesday.

&&

$$

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