wi discuss
Office: MKX
FXUS63 KMKX 300837
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
337 AM CDT Wed Apr 30 2025
.KEY MESSAGES...
- Widespread light rain expected late tonight through Thursday.
A few rumbles of thunder will be possible in far southeast WI.
&&
.SHORT TERM...
Issued 336 AM CDT Wed Apr 30 2025
Today through Thursday:
An area of low clouds developed near Green Bay late last evening
and slowly expanded into east central WI overnight. The
trajectory keeps them confined to Sheboygan and Fond du Lac
counties early this morning, and then mixing will help them
dissipate by mid morning. Temperatures dropped into the upper
30s across much of east central and southeast WI thanks to cool
air from Lake Michigan on slightly enhanced northeast winds.
Winds were probably too high to allow for frost development.
There will be a large difference in temps between the lakeshore
and western Waukesha County (and north-south of there) due to a
steady east wind off Lake Michigan all day. Inland temps should
reach the mid to upper 60s from Madison and westward.
Dewpoints are in the 30s and they are not expected to make much
headway into the 40s today, per the upstream obs in IA and IL.
Therefore, min RH values will be in the 35 to 40 percent range.
The arrival time of the precip today looks slower than
previously forecast due to all the dry air in place over WI.
The convection ongoing over MO will lift into the Upper Midwest
later today. However, the nose of the LLJ (and vorticity
advection with a southern stream upper trough) that are driving
that convection is expected to split around southern WI. This
means that one wing of the precip will track into northeast IL
today and lower Michigan this evening; the other wing of precip
will track northward into southern MN, following the right
entrance region of the upper jet and a mid level shortwave
trough.
Eventually, the southern stream shortwave trough will
push into the mid Mississippi River valley and a more connected
flow from there into southeast WI will develop overnight. Thus,
that is when the more widespread showers will arrive in
southeast and east central WI. However, the disjointed upper
levels between the southern stream upper trough and northern
stream upper trough means that south central WI and central WI
will likely have lower precip amounts from this system. Total
rainfall amounts are forecast to range from around 0.75 inch in
southeast/east central WI to 0.35 inch in south central/central
WI.
A surface low will develop over central IL as the MS River
valley mid level shortwave trough gets closer. That surface low
will slide across southern Lower MI during the day Thursday, and
the steadier showers over southeast WI will taper off from west
to east from Thursday afternoon through Friday evening.
Given that we will be on the northwest periphery of the main
forcing of this system, our chance for thunder is very low. The
steeper mid level lapse rates should be limited to right along
the WI/IL border late tonight through Thursday. Elsewhere, lapse
rates look moist adiabatic and thus quite stable.
Temps Thursday will remain cooler by the lake, especially
toward east central WI due to steady northeast winds. Inland
highs will be in the upper 50s, except lower 60s near the WI/IL
border.
Cronce
&&
.LONG TERM...
Issued 336 AM CDT Wed Apr 30 2025
Thursday night through Tuesday:
Meanwhile, the northern stream upper trough will be slow to make
eastward progress. This will bring additional light showers to
southern WI Thursday night. While shower chances continue
through Friday due to the upper trough passing overhead, the dry
air surging in from the north may win out and keep us dry. Any
precip will not be a steady rain, but instead characterized by
several waves of light to moderate showers, as various
shortwaves rotate through the larger scale upper trough. Highs
Friday will be a touch cooler, with readings in the mid to upper
50s to around 60.
The main upper level trough is expected to pass through the area
Friday night, with high pressure building into the region on
Saturday. Guidance is suggesting that an omega block will set up
across the CONUS, with deep troughs/upper lows over the eastern
and western US, and a strong ridge over the central part of the
country. This suggests a stretch of quiet and warm weather as high
pressure slowly drifts eastward, with highs early next week
approaching the upper 70s and low 80s.
Boxell
&&
.AVIATION...
Issued 336 AM CDT Wed Apr 30 2025
An area of low clouds developed near Green Bay late last evening
and slowly expanded into east central WI overnight. The
trajectory keeps them confined to Sheboygan and Fond du Lac
counties early this morning, and then mixing will help them
dissipate by mid morning. Northeast winds are elevated near Lake
Michigan and lighter for inland areas. High clouds will continue
streaming into southern WI from a storm complex crossing the
MO and IL today.
Light rain chances should hold off for southern WI until
evening, although virga is possible. Then more widespread
showers should develop in southeast and east central WI
overnight tonight. A few rumbles of thunder will be possible
near the IL border.
VFR today. Ceilings will fall tonight as the rain moves in,
with IFR expected after midnight and through at least Thursday
morning.
Cronce
&&
.MARINE...
Issued 336 AM CDT Wed Apr 30 2025
High pressure of 30.3 inches centered over Upper Michigan will
cross Lake Huron today. Steady easterly winds will persist through
Wednesday night, then increase Thursday as low pressure around
29.6 inches tracks from IL to southern Lower Michigan.
Winds will become northerly Thursday afternoon and westerly
Friday afternoon as that low exits the region. High pressure
around 30.2 inches will return to the Upper Great Lakes for the
weekend, bringing quiet weather and light winds to the region.
Cronce
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&
$$
Visit us at weather.gov/milwaukee
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSMilwaukee
www.twitter.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee
Office: ARX
FXUS63 KARX 301025
AFDARX
Area Forecast Discussion
National Weather Service La Crosse WI
525 AM CDT Wed Apr 30 2025
.KEY MESSAGES...
- Periodic showers and a few thunderstorms this afternoon
through Thursday evening. Rain amounts are roughly 0.1" to
0.25" for areas along and north of I-94 and 0.25" to 0.4" for
areas south of I- 94.
- Warming trend this weekend. High temperatures warming into
the mid to upper 70s by Sunday and possibly near 80 in a few
locations by early next week.
&&
.DISCUSSION...
Issued at 309 AM CDT Wed Apr 30 2025
Today-Friday: Near Normal Temperatures, Periodic Rain and
Thunderstorm Chances:
Ahead of an approaching upper level low from the southern Plains and
a shortwave trough dipping down into the Upper Midwest, southwest
flow aloft is over the area through the day. This will help mix us
out a little and as a result, high temperatures warm into mid to
upper 60s. Rain chances increase during the afternoon across
northeast Iowa, southeast Iowa, and southwestern Wisconsin as the
upper level low shoots off some shortwave impulses into the area.
Initially the lower levels will be drier and may take a couple hours
to saturate enough for the rain to reach the surface. Some light
rain showers will be possible until enough saturation takes place. A
few thunderstorms will also be possible this evening through
Thursday evening primarily along and south of I-90 as 100-300
J/kg of MUCAPE moves into the area. There is still some
uncertainty in the CAMs as far as coverage of these showers and
thunderstorms and where the higher rain totals will be located
at.
After Thursday evening, the upper level low moves off to the
northeast and we transition to northwest flow aloft as the shortwave
trough shifts into our region. This will give the area 20 to 40%
chance at some showers for Friday. All precipitation chances are
expected to diminish by evening. Overall rain amounts have changed
slightly for the forecast area with locations to the north of I-94
receiving 0.1" to 0.25" and locations to the south of I-94
potentially receiving anywhere from 0.25" to 0.4". High temperatures
for Thursday and Friday cool slightly compared to today, ranging
from the upper 50s to mid 60s.
Saturday-Early Next Week: Warmer Temperatures and Drier?
Once the trough moves off to the east, ridging builds into the area.
While the region remains in northwest flow, temperatures only warm
slightly compared to Friday, into the mid to upper 60s, however by
Sunday and early next week, southwest flow returns and helps to warm
our temperatures into the mid to upper 70s and even near 80 degrees
for some locations. Dry conditions are expected for the weekend.
There are some differences in the deterministic models on how
early next week pans out. The EC and CMC have an omega block
pattern over the central US from Saturday through Wednesday
while the GFS brings a shortwave on Monday and shortwave
impulses for Tuesday and Wednesday that could increase
precipitation chances. Current ensemble guidance does have a low
chance for rain to return early next week, however it is
roughly 20-30% of all ensemble members. The majority of ensemble
members keep us dry through at least the middle of next week.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 525 AM CDT Wed Apr 30 2025
VFR conditions throughout the daytime hours will give way to MVFR
and eventually IFR cigs overnight. Winds will remain around 8-12 kts
during the afternoon before diminishing and switching to the east
with sct to bkn high clouds. As a weather system approaches the
area, cigs will decrease to MVFR (70-90% chance in the 30.00z HREF)
and eventually IFR (50-80% chance in the 30.00z HREF) by 12z.
Additionally, scattered to numerous showers will move into the area
with visibility reductions to MVFR and perhaps IFR at times.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Cecava
AVIATION...Naylor
Office: GRB
FXUS63 KGRB 301141
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
641 AM CDT Wed Apr 30 2025
Updated aviation portion for 12Z TAF issuance
.KEY MESSAGES...
- Next opportunity for rain is Wednesday night through Friday.
Expecting mainly rain, thunder chances are low.
- Dry and warmer weather this weekend and into early next week.
There is a 50-80% chance of high temps of 70+ on Sunday away
from the lake sore.
&&
.DISCUSSION...
Issued at 502 AM CDT Wed Apr 30 2025
Low clouds formed off of Lake Michigan and expanded westward
overnight, which has left much of the forecast area under a low
cloud deck. Easterly winds have also held up, contributing to the
expansion of these clouds. Therefore, temperatures have remained a
little warmer than expected in the mid 30s for most locations as
of 09Z. Places where skies were still clear (Land O' Lakes and
northern Door County) were cooler and had calm winds.
It took models a bit to pick up on this cloud trend, mainly
followed the HREF and NBM for cloud coverage today. Low clouds
continue to hang around through midday, and then scattered out as
winds veer to the south. This is quickly followed by increasing
high clouds ahead of the next weather system. So, looking at a
partly to mostly cloudy sky today, which may have a slight
influence on temperatures. But, the late day warm advection and
any breaks in the clouds should help. Forecast highs are in the
upper 50s and low 60s, and cooler along the lake shore in the mid
40s to low 50s.
Focus shifts to a few rounds of rain from tonight through Friday.
There is a shortwave/sfc low moving up from the southwest,
quickly followed by one from the northwest. Still some timing and
track differences, but either way overall impacts will be low.
First low approaches tonight and moves south of WI on Thursday.
Some models have pulled this farther south, leading to little
precip getting into the GRB forecast area; while others still
bringing in light rain, at least for the southern half. Slowed
down arrival of PoPs until around or after midnight which continue
through Thursday. Just as this system departs a shortwave/low
moves in from the northwest, bringing another round of light to
moderate Thursday night into Friday morning. With some lingering
moisture and lift possibly into Friday afternoon--especially
across northern WI. Rainfall totals from 12AM Thursday through 7PM
Friday range from ~0.25 to 0.50 inches, which does not trigger
any flooding concerns. Cannot rule out some embedded thunder on
Thursday with a few spots of 100-200 J/kg of CAPE present, but
overall thunder chances are low and severe weather is not
expected.
High pressure builds in for the weekend leading to pleasant
weather conditions. Dry weather is expected from Saturday through
at least Monday, with high temps in the 60s on Saturday, and 70s
for most from Sunday-Wednesday.
&&
.AVIATION...for 12Z TAF Issuance
Issued at 641 AM CDT Wed Apr 30 2025
Low clouds had spread across the area overnight with a mix of
MVFR/IFR/LIFR cigs across the area, lowest across north-central
WI as of 1130Z. There were also localized pockets of fog which had
formed in far north-central WI where skies were clear most of the
night, with some vsbys as low as 1-3SM. Expect any fog to
quickly dissipate as the sun rises. Low clouds will also lift and
scattered during the mid-morning, with high clouds spread in above
them. Once the low clouds dissipate VFR conditions are expected
through the rest of the TAF period. Light rain arrives late tonight
(around 7-9Z), but lower flight conditions likely do not arrive
until after 12Z/Thu.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....KLJ
AVIATION.......KLJ
