Area Forecast Discussion Issued by NWS Milwaukee/Sullivan, WI
000
FXUS63 KMKX 101645
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1145 AM CDT Wed Apr 10 2024
.KEY MESSAGES...
- Increasing shower potential Thursday with a few rumbles of
thunder, but uncertainty in rainfall amounts remains due to
large model spread in potential totals.
- River flooding will continue through the weekend on isolated
portions of the Lower Fox and Rock Rivers. Additional rises
and possible flooding on area rivers will be possible with
Thursday`s rainfall.
- Gusty northwest winds are expected through most of Friday,
with gales possible on the open waters of Lake Michigan.
- Above normal temps today and again this weekend with high
potential (>75%) for daily highs to exceed 70F this weekend.
&&
.UPDATE...
Issued 1034 AM CDT Wed Apr 10 2024
High based cumulus is beginning to develop over south central WI
with some expected farther east, but could be limited in far se
WI due to high cloud cover. The lake breeze is currently along
the Kenosha lakefront, but should develop along the entire
shoreline and move inland through the afternoon and early
evening. High temps in the upper 60s still looks good.
Delayed the rain for late tnt-Thu AM as 12Z GEFS and 12Z GFS is
tracking the lower MS River cyclogenesis farther ewd to Lake
Erie by 00Z Fri. Thus the digging and amplifying shortwave
trough currently over the high nrn Great Plains will be the main
catalyst for showers and sct storms Thu-Thu nt. Confluent flow
btwn the two systems will lead to low level frontogenesis and an
inverted trough over srn WI with some marginal CAPE expected.
Numerous showers and sct storms will develop over south central
WI by early Thu afternoon with some development ewd into Thu nt.
Gehring
&&
.SHORT TERM...
Issued 345 AM CDT Wed Apr 10 2024
Today through Thursday night:
Broad area of high pressure will be chased out of the area
through the afternoon. As a result, southwesterly flow will
become more prevalent ahead of the surface low workings its way
up the lower Mississippi River Valley. With this setup, looking
at the warmest day of the week with ensemble mean max temps
climbing well into the 60s this afternoon with a few spots
cracking 70F. Would not be surprised to see a few spots even
trend toward the 75th-90th percentile values in the lower to mid
70s given the ample sunshine. However, given the light wind
field and strong thermal gradient between inland temps and the
much cooler Lake Michigan surface temps in the lower 40s, likely
will see a lake breeze develop this afternoon. Thus areas along
the lakefront will likely be on the cooler side of the temps
trend for the afternoon. Otherwise, today will a be very warm
spring day with overnight lows in 40s.
The warmer above normal temps will be brief as the
aforementioned surface low lifts farther north-northeast over
the conjecture of the Mississippi and Ohio Rivers overnight and
through IN during the day Thursday. Models continue to show the
low to deepening as it lifts into MI later on Thursday as two
upper-level troughs phase over the region. While, the 00z EPS
and GEFS ensemble members generally agree on the low track, the
mid-level troughs phasing gives me a bit of pause as a shift in
the track is not out of the question, but consensus continues to
show southern WI on the cold side of this system.
Nevertheless, this system on Thursday will bring our next round
of active weather, but will be warm enough for it all to be
rain. Expect the upper-level dynamics to align over the region
bringing plenty of forcing and moisture for widespread shower
activity through the day Thursday. Onset timing of the showers
seems to be slightly later given the influence of the high-res
models. Could see showers move into our neck of the woods as
early as 09z Thursday, but the better chances pick up after 12z
as the low deepens and upper-level trough work their way across
the Upper Great Lake Region. With the two separate upper-level
trough progged to phase, there looks to be two areas of forcing
and shower activity, which are being picked up on the 00z HREF.
The initial wave associated with the southern trough looks to
move in earlier and will bring the initial showers from the
south-southeast through the morning. Then another area of
showers associated with the northern trough looks develop to the
northwest later Thursday morning into the afternoon. As the
troughs phase, some of the CAMs, such as the 00z HRRR and
NAMnest, are picking up on a north to south line of showers
ramping up across the western half of the CWA, which would be a
focus of deeper showers, heavier rainfall, and even a few
rumbles of thunder with hints of instability (<500 J/kg). While
shower potential remains high (>70%), there remains a large
spread (0.5->1 inch on the 00z NBM) between QPF 24 hour totals,
so some question remains on exact rainfall amounts with this
system.
Otherwise, showers chances will linger through the evening and
diminish overnight as the surface low kicks further northeast.
In addition to the increased rain chances, the strong pressure
gradient from the deepening low to sub-990 mb will likely result
in increasing north-northwesterly winds later Thursday.
Wagner
&&
.LONG TERM...
Issued 345 AM CDT Wed Apr 10 2024
Friday through Tuesday:
The tight pressure gradient persists into Friday and expecting
stronger north-northwesterly with gusts likely exceeding 25-30
mph through Friday afternoon before easing into the evening.
Expect quieter, and warmer conditions for the weekend as upper-
level ridge builds over the Central CONUS. There are increasing
probabilities (>75%) to see high temps exceed 70F on both
Saturday and Sunday across southern WI with even a low-medium
chance (20-50%) to exceed 80F on Sunday. Nevertheless, it looks
to be a warm spring weekend ahead.
Above normal warmth looks to continue into the start of next
week, but the pattern is trending a bit more active. While
still seeing run-to-run variability, the 00z GFS and ECMWF both
are hinting at deepening system trekking into the Upper Midwest
for Tuesday. Again still a great deal on uncertainty being so
far out, but is a system that bears keeping an eye on and how it
evolves over the coming days.
Wagner
&&
.AVIATION...
Issued 1034 AM CDT Wed Apr 10 2024
VFR conditions today and tonight with scattered high based
cumulus this afternoon. Showers and scattered storms then
expected by Thu afternoon over much of srn WI. Areas of MVFR
Cigs may form over far se WI from Thu AM into Thu PM.
Gehring
&&
.MARINE...
Issued 345 AM CDT Wed Apr 10 2024
Light to moderate southwest to southerly winds will persist
today and tonight as weak high pressure is pushed east by an
area of low pressure tracking across the Upper Midwest today.
Winds will increase and turn more east-northeasterly heading
into Thursday as a stronger low pressure deepens it lifts
across the lower Mississippi and Ohio River Valleys. With the
strong pressure gradient, expect gusts up to around 30 knots
with small craft conditions likely, but cannot rule out a few
gale force gusts on Thursday. The low pressure continues to
deepen as it lifts across IN into lower MI through Thursday
night. Widespread gusts exceeding 30 knots are expected on the
backside of the departing low and while there remains some
uncertainty, there is a potential for gales through the day
Friday. Will continue to monitor trends for stronger
northwesterly winds/gales on Friday to assess marine headlines.
Otherwise, the low lifts across eastern Ontario and Quebec
later Friday and into Saturday and winds weaken across Lake
Michigan for the weekend.
Wagner
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&
$$
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