NWS Milwaukee Forecast Discussion
337
FXUS63 KMKX 042005
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
305 PM CDT Sat May 4 2024
.KEY MESSAGES...
- A line of showers and thunderstorms will develop this
afternoon and evening bringing brief heavy downpours. There
may be a few strong thunderstorms within the line capable of
producing hail and gusty winds for areas along and east of
HWY-151 to around I-41.
- Quiet and dry weather expected for Sunday into early next
week.
- Additional showers and thunderstorms are expected during the
middle portions of next week.
&&
.SHORT TERM...
Issued 302 PM CDT Sat May 4 2024
Tonight through Sunday night:
The initial morning line of showers have diminished and pockets of
clear are resulting in temps warming into the low to mid 70s across
much of the area. Clouds are looking a bit more agitated on the
latest visible/RGB satellite imagery ahead of the cold front
which looks to strewn through far southwestern WI. Convective
initiation is starting with a cell deepen over Jo Davies County
just south of the WI/IL border. Expect this activity to develop
over the next few hours as the cold front gradually slides
east.
The environment ahead of the front has warmed and moisten with
dewpoints in the mid 50s to mid 60s allowing SBCAPE to build to
around a 1000-1500 J/kg this afternoon along the WI/IL border
with the 500 J/kg contour extending up into the upper Fox River
Valley. Pair the instability with marginal deep layer shear
values around 35- 40kt and looks to be enough for storms to
develop along the cold front through the afternoon. Some
stronger thunderstorms will be possible with this activity
given the overachieving environment. Thinking any hail threat
will be over the next couple of hours as storms begin to
develop before the merging into a line. While the effective bulk
shear is looking a bit less parallel at this time, the 0-3 km
bulk shear still remains along a similar orientation as the cold
front favoring a linear storm mode. However, with the
inverted-V on model soundings and steep low-level lapse around
+7.5 C/km, thing the threat for gusty to damaging winds will
increase through the evening as the line matures. Again would
not be surprised to see an embedded segment of the line to grow
upscale and become severe especially along the WI/IL where an
early MCV from northeastern MO lifts into northern IL. Again may
see hail up to around an inch early on, but more of a damaging
wind threat through the evening. While it is not out of the
realm of possibility given some remnant outflows and potential
lake breeze interaction increasing low-level (0-1km) shear,
cannot rule out a brief spinup along the line, especially with
any bowing/surges. But given more parallel shear, chances
remain very low.
Nevertheless, the potential for strong storms along with a brief
downpour will continue now through the evening mainly pushing east
and over the lake between 01-03z. The main area of concern looks to
still be a slice from just west of Monroe up through Green Lake and
Fond du Lac County down through Burlington/Lake Geneva/Twin Lakes.
Still think chances will be limited along the lakefront given the
persistent onshore flow, more stable environment, and later arrival.
Otherwise, the cold front pushes through this evening bringing drier
airmass and quickly diminishing precip chances. Clouds may linger a
bit longer as well possibly through daybreak Sunday. Then surface
high pressure is progged to build across the area for Sunday
bringing light and variable winds. Still looking to see temps warm
into the 60s and given the light flow, a lake breeze may develop and
push inland. Thus temps will be cooler by the lake for Sunday. High
pressure influence will linger through Sunday night bringing a crisp
conditions as mostly clear skies and light winds allow temps to
drop. While temps look to only fall into the low 40s, but cannot
rule out a few inland locations to fall into the upper 30s
with a potential for some frost development.
Wagner
&&
.LONG TERM...
Issued 302 PM CDT Sat May 4 2024
Monday through Saturday:
Low pressure occluding over the Northern Plains will be our next
weather maker for southern WI Monday night through Thursday.
Increasing southeast winds can be expected Monday, along with
increasing high clouds. Showers and thunderstorms are expected along
the warm front that will be slowly lifting east-northeast into
southern WI Monday night. The trend for the arrival time of precip
is slower/later, which is no surprise given the nature of upper
lows.
With this warm front, elevated instability looks to be weak/modest
(around 750 j/kg) as it lifts across southern WI Tue morning. Mid
level forcing of vorticity advection and low level jet will be
weakening during this time. Hail would be possible in any
stronger storms. Tuesday afternoon looks like a drier, reload
period, although there are plenty of timing differences between
the models this far out. Another round of showers and
thunderstorms is possible over south central and southeast WI,
probably south of I-94, and this is due to another lobe of
vorticity advection rotating through and the potential for the
surface warm front to sneak north of the WI/IL border. The lake
breeze may help (initiate convection) or hinder (shunt the warm
front to the south) in southeast WI, so we will need to keep an
eye on this.
Wednesday is looking fairly dry and warm at this time. The upper
low will start to move into MN Wed night. Another round of showers
and thunderstorms is possible over southern WI Wed nt into Thu. We
will be stuck under a large upper trough through Saturday and
potentially longer. Expect chances of showers and storms through
this period.
Cronce
&&
.AVIATION...
Issued 302 PM CDT Sat May 4 2024
A line of showers and few thunderstorms will continue to develop
across southwestern WI through the afternoon and trek east along the
cold front through the evening. This line looks to bring brief,
heavy downpours, small hail, and gusty winds along with lower
visibility and ceilings. The deteriorating conditions will be
limited to a narrow 2-4 hr window as the line tracks over the lake
by 01-03z. Lower ceilings may linger a bit longer overnight and
possibly into early Sunday morning, but drier conditions are
expected to build in with high pressure for Sunday behind the cold
front.
Otherwise, expect south-southeasterly winds through the afternoon
before turning west-northwest by tonight behind the cold frontal
passage. Light and variable winds along with prevailing VFR
conditions expected for Sunday as the high works across the area.
May see a winds pick up and shift more easterly Sunday afternoon as
a lake breeze is progged to develop and push inland.
Wagner
&&
.MARINE...
Issued 302 PM CDT Sat May 4 2024
Some marine dense fog looks to linger through the afternoon along
the western open waters and western nearshores given the warm, moist
air over the cooler lake.
Otherwise a broad area of low pressure will continue to work its way
eastward from WI and over the Lake tonight. This will drag a cold
front across the lake overnight and shift winds from the east-
southeast to the west-northwest. Will see scattered showers and
thunderstorms with some gusty winds and small hail possible along
the front. But it will be drier by Sunday morning as high pressure
begins to build into the western Great Lakes region. Expect lighter
and more variable winds for Sunday into Monday as the high pressure
works its way across the region. Winds then begin to shift out of
the east-southeast Monday afternoon and evening as another low
pressure develops and deepens over the northern Plains. Winds will
pivot between southeasterly and southwesterly through mid- week,
prior to turning out of the north and northwest on Thursday and
Friday as another low pressure moves east of the open waters.
Periods of showers and thunderstorms are forecast from early to mid
week, with conditions drying out by the end of the week and
beginning of next weekend.
Wagner
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Dense Fog Advisory...LMZ080-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ643-LMZ644-LMZ645-LMZ646-LMZ669-LMZ671-LMZ673-LMZ675-
LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878
until 7 PM Saturday.
&&
$$
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