NWS Milwaukee Forecast Discussion
000
FXUS63 KMKX 270243
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
943 PM CDT Fri Apr 26 2024
.KEY MESSAGES...
- Multiple rounds of showers and thunderstorms are expected
tonight through the weekend, with storms possibly lingering
into early Monday. Locally heavy rainfall will be possible,
especially south and west of Madison.
- A few thunderstorms may be severe during this active pattern,
particularly later Saturday through Sunday.
- Additional chances for showers and storms mid to late week
next week.
&&
.UPDATE...
Issued 940 PM CDT Fri Apr 26 2024
Continue to monitor for thunderstorm potential tonight as the
surface low lifts into MN lifting a warm front across southern
WI. Trends continue to slow this northward progression of the
warm front as it is currently draped across southern IA through
central IL. Latest 00z models coming in have the front lifting
in later than previous forecast around 04z-06z. However there is
still a question on if anything develops along this frontal
boundary as it moves into a more stable environment. Thus the
later the arrival of the surface warm front the less likely to
see thunderstorms develop along this boundary as hinted at by
the 00z ARW. However most of the other incoming 00z models such
as the HRRR and NAM Nest have at least a few showers and storms
developing after 04z and quickly moving through the area as LLJ
lingers paired with low-level WAA and an approaching warm front.
00z Rap still tries to bring in a nose of 250-500 J/kg of
instability, thus still can`t rule out a few storms to produced
some small hail. Otherwise, with a stronger, 45-55 kt LLJ,
cannot rule out some gustier winds with any thunderstorms as
well.
Overall, the best thunderstorm chances remain along and west of
the I-39/90 corridor tonight, but the later arrival trends
continues to limit the potential for any stronger storms. This
activity should diminish by 09z as the warm sector settles into
the region. Drier, warmer conditions look to persist into
Saturday before the cold front moves into the region and
triggers another round of showers and storms.
Wagner
&&
.SHORT TERM...
Issued 356 PM CDT Fri Apr 26 2024
Tonight and Saturday:
Rain showers continue to push in from the south, with some
rumbles of thunder embedded throughout the system. Current low
level profiles remain drier while the upper levels moisten with
the oncoming rain, helping to keep rainfall values around light to
moderate across the area. This rain will continue to push in
throughout the afternoon and evening, before a brief reprieve as
it traverses towards the northeast.
Behind this initial band of rain, more rain follows the warm
frontal boundary with an associated low pressure currently over
Nebraska. With this line of rain, some embedded thunderstorms are
anticipated, with greater lift along the boundary and more energy
following warm air advection into the region. As the low pressure
exits towards the northern Great Lakes region by Saturday morning,
temperatures will climb with stronger southwesterly winds
prevailing. Isolated thunderstorms are possible in the afternoon
hours, although most regions are expected to stay dry. Going
into the evening on Saturday, a greater severe threat begins to
take shape.
Gertonson
&&
.LONG TERM...
Issued 356 PM CDT Fri Apr 26 2024
Saturday night through Friday:
Frontal feature hanging over central Wisconsin will slowly sink
southward as low pressure approaches from the central Great
Plains once again Saturday night. With surface dewpoints in the
lower 60s and temperatures in the lower 70s, surface based CAPE
values close to 2000 J/kg in the evening hours are possible,
with CAPE above 1500 J/kg likely. Mid level lapse rates of 6.5
to 7 degrees C/km lends credence to continued concern for 1 inch
or larger hail with the initial convection within the unstable
layer. Gusty winds are also possible with this activity as dry
air intrudes in the 700 to 500 mb layer and PGF increases ahead
of the next low pressure pushing eastward. Increasing helicity
ahead of the front (200 to 300 m2/s2) may result in an isolated
tornado, although confidence in this hazard remains low.
Frontal convection continues through Saturday night into Sunday,
with any individual cells continuing to be capable of producing
hail. However, increasing stability in the boundary layer will
keep storms elevated and reduce any severe winds or lingering tornado
potential. Sunday morning, low pressure begins to sweep
northeastward toward Minnesota, bringing better bulk shear (40
to 50 kt) to the area as southerly winds continue to increase.
Cloud cover through the morning may prevent warming, and
location of the frontal feature may produce a 10 or more degree
F difference in temperature from central Wisconsin to southern
Wisconsin. Still, temperatures in the lower 70s and dewpoints in
the lower 60s lend credence to another round of thunderstorms in
southern Wisconsin Sunday afternoon and evening as WAA and an
850 mb jet act as the main trigger and MUCAPE producers.
Potential for hail and gusty winds are once again in play.
Trends have been slower with the progression of the main cold
frontal feature, leading to continued concerns for thunderstorms
into Monday. Southerly to southwesterly flow continues
throughout Monday morning, with frontal passage currently
forecast early Monday afternoon. Temperatures are expected to
rise to near 70 degrees across all of southern Wisconsin, with
westerly component allowing for warming all the way to Lake
Michigan. Uncertainty remains in intensity of convection on
Monday due to uncertainty in precursory convection and impact of
previous days convection on the propagation of the low.
A brief period of quiet, dry weather on Tuesday, then an
additional shortwave comes through the region Tuesday night,
with additional shortwaves and perhaps a stronger low pressure
system developing and impacting southern Wisconsin through the
end of the week.
MH
&&
.AVIATION...
Issued 940 PM CDT Fri Apr 26 2024
Some light scattered rain is working its way across the area
late this evening with another round of scattered showers
possible between 04z-09z as a warm front is progged to lift into
the southern WI overnight. Cannot rule a rumble of thunder or
two with the overnight activity, especially for MSN and JVL
terminals. However this window will be brief. Lower ceilings are
lingering across southwest and south central WI bring lower
ceiling around IFR to MVFR levels, while VFR are more present
closer to the Lake. Can see lower visibilities and ceilings drop
with and shower that passes over the terminals. Otherwise, will
continue to see gusty southeasterly winds tonight turning a bit
more southerly more into Saturday morning as warm front lifts
north. Flight conditions are expected to improve as ceilings
lift with the drier conditions. However, another round of
showers and storms, potential strong to severe return later
Saturday as a cold front slides across the region bringing back
the lower flight conditions.
Wagner
&&
.MARINE...
Issued 356 PM CDT Fri Apr 26 2024
Low pressure over the central Great Plains will lift into
Minnesota tonight, with gusty southeasterly winds expected. A
few gusts late tonight into Saturday morning may approach gale
force, especially in the northern half of the Lake, as the low
continues to lift into Lake Superior. Winds will then become
light and northeasterly Saturday night into Sunday morning as
the low exits and a weak cold front drapes across central
portions of the lake. Sunday into Sunday night, winds will
become breezy and southerly south of the front and will become
breezy and easterly to northeasterly north of the front. A Small
Craft Advisory is in place through Monday for gusty winds and
elevated wave conditions. A lull may occur late Saturday night
into Sunday, with increased gustiness once again Monday.
A few thunderstorms are possible this evening into tonight across
the southern half of the lake, lifting into the northern half
Saturday morning. Additional rounds of showers and thunderstorms
are expected Saturday and Sunday. A few storms in the afternoon
hours could produce locally gusty winds.
MH
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 7 PM
Monday.
&&
$$
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