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000
FXUS63 KMKX 160845
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
345 AM CDT Tue Apr 16 2024

.KEY MESSAGES...

- Approaching Wind Advisory criteria this afternoon for strong
  east to southeast winds

- Rounds of showers and storms will likely (60-85%) bring over
  an inch of rain this afternoon through Wednesday afternoon
  with pockets to around 2 inches possible especially over south
  central WI.

- There is a conditional severe threat for far south central WI
  this afternoon and evening.

&&

.SHORT TERM...
Issued 345 AM CDT Tue Apr 16 2024

Today through Wednesday night:

Higher clouds will gradually push in this morning as the surface
low slides east through the Central Plains. Overall the day will
be relatively warm and breezy. 925mb temperatures will be warm
enough to bring areas near the WI/IL border to near 70 degrees
while much of the rest of the area should (60-70%) reach the
low to mid 60s outside of areas near the lake where the lake
will keep them cooler given the breezy easterly flow off the
lake. As for winds the WAA just off the deck will inhibit crazy
mixing heights but you will not have to mix very high to tap
into 35-40kt winds aloft right around 925mb. We did consider a
Wind Advisory for parts of the area today but these higher end
winds seem fairly limited in time and still remain fairly
borderline.

Moving later into the afternoon dry conditions ahead of the
system any showers that pop up out ahead of the main forcing (as
seen in a few CAMs) may (50-60%) not reach the ground. However
once the main forcing aloft with the upper low pushes in we will
see the rain and storm potential rapidly increase. This will be
coincident with the increasing LLJ. Overall the initial wave of
precip will likely occur in a 3-4 hr window for a given
location between 5pm and midnight. As storms slide east during
the evening gradual weakening will be expected (90%). We still
see some potential (30-40%) for a few strong to severe storms in
the southwest portions of the CWA primarily.

Our severe potential is fairly conditional on just how far
north the warm front gets and how much instability there will
be. Currently it appears the warm front may (60%) just sneak
north enough to bring severe potential to the southwest part of
the CWA with upwards of 1000-1500 J/kg of MLCAPE. Given the
0-6km shear being upwards of 50-60 kts the severe potential is
certainly there. The concern comes in with how CAMs are
developing storms, storm mode, and precip/storms potential ahead
of the main convection. All of this adds uncertainty but if we
get a well formed line of storms pushing through damaging winds
and QLCS tornadoes could be a concern, while if it is more
cellular hail becomes the primary concern. Either way potential
remains fairly limited overall given the conditions needed for
stronger storms but over the next 6-12 hours we will have a
better idea of exactly what this is going to look like. Areas
further east are not as likely (20-30%) to see the warm front
push far enough north, due in part to the lake. Thus severe
potential is limited to the southwest with maybe a stronger
elevated storm sneaking further north.

The main period of convection should end by around midnight with
a period of dry conditions likely (60-70%) through the late
night period as the area sits in the dry slot. However, by the
early morning hours around daybreak most of the CAMs suggest a
few more storms could develop across the CWA associated with the
upper low/surface low and perhaps forming off the occluded
front. While severe storms are not expected (10-20%) from this
the shear may potentially large enough to cause a bit of
organization to these storms to be a bit stronger than expected.
Otherwise the rest of the day will feature scattered to
isolated showers associated with the upper low primarily. By the
evening the system will likely (80%) have shifted far enough
east to bring back drier conditions to the region.

I should additional mention the hydro concerns with this event
as we could see widespread precip amounts of 0.75-1.25 inches
with some chances (30-40%) for some spots to the west to see
upwards of 2 inches or rain. This will be on the backs of
transient PWATs of 1.25-1.5 inches. A few rivers in the western
part of the CWA will likely (60-70%) be impacted and that will
be the main thing to monitor regarding impacts from rain
amounts. Rates will be the secondary thing to watch with this
system but overall flash flooding is not expected at this time.

Kuroski

&&

.LONG TERM...
Issued 345 AM CDT Tue Apr 16 2024

Thursday through Monday:

A shortwave trough digging through the Central Plains from NE to
IL Wednesday night into Thursday will be the focus for our next
chance of rain across southern WI. A narrow area of 600-700mb
frontogenesis is expected to slide across southern WI Thursday
afternoon. This should be enough to saturate the mid levels for a
few hours, and light rain is likely (60-70%) for areas along and
west of a Wisconsin Dells-Madison-Janesville line. Models have
been fairly consistent with this signal of light QPF, and precip
amounts should be less than 0.10 inch.

We will enter into a lengthy period of fairly dry northwest flow
from Friday through Thursday. Temperatures will be at or below
normal for most of the period, with normal highs in the upper 50s
to around 60 for mid to late April. Lows will be in the 30s Friday
night and through Sunday night. Saturday night looks the coldest
with below freezing temps possible.

A shortwave trough crossing the Central Plains Monday and Monday
night will help us warm briefly. There is a chance of rain with
this feature, although there are model differences in the track of
this associated low and therefore the precip. It looks like the
pattern will change back to warm and unsettled beyond Day 7.

Cronce

&&

.AVIATION...
Issued 345 AM CDT Tue Apr 16 2024

VFR TAFs expected through at least the early afternoon though
winds will pick up by the late afternoon with east to southeast
winds gusting as high as 40 knots, especially toward central
Wisconsin (this will continue into the evening ahead of storms).
By the late afternoon and early evening showers and storms will
start to push in from the west that will be coincident with
some MVFR CIGS and likely (60-70%) some reduced VSBYS with
heavier rain (heavy rain more likely further west). By the
evening hours we should (70%) see most of the rain/storms push
out with a period of dry condition, though MVFR CIGS will
continue. Overnight will remain fairly quiet with additional
storm development probably (70%) around daybreak Wednesday
morning with spotty showers thereafter. Overnight into Wednesday
morning may (40%) feature CIGS falling to IFR for a period
though CIGS should be expected to improve from the west during
day Wednesday as the system gradually pushes out.

Kuroski

&&

.MARINE...
Issued 345 AM CDT Tue Apr 16 2024

Easterly winds will continue across the lake this morning as low
pressure continues northeast towards the Great Lakes region.
Winds today will remain easterly, but will begin to accelerate
throughout the day as the low approaches, leading to the
likelihood of gales across much of the lake by this evening.
As such, we have upgraded the Gale Watch to a Gale Warning that
is in effect from this evening through Wednesday evening for
various parts of the lake. In addition we issued a Small Craft
leading into the Gale Warning for high waves and strong
easterly winds from 25 to 30 kts. Winds across much of the lake
will decelerate and shift southerly to southwesterly Wednesday
as the low moves north across central Wisconsin, but easterly
gales are still possible over the far northern portion through
Wednesday evening before also turning westerly and decelerating.
Westerly winds will then continue Thursday morning before
becoming southwesterly by Thursday afternoon for the entire lake
as the low departs the area. A Small Craft will likely be
needed for parts of the nearshore following the end of the Gale
Warning for a least a short period.

Kuroski

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...10 AM
     Tuesday to 6 PM Tuesday.

     Gale Warning...LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-LMZ643-
     LMZ669-LMZ671-LMZ868-LMZ870-LMZ872...6 PM Tuesday to 7 AM
     Wednesday.

     Gale Warning...LMZ080-LMZ644-LMZ645-LMZ646-LMZ673-LMZ675-
     LMZ777-LMZ779-LMZ874-LMZ876-LMZ878...6 PM Tuesday to 1 AM
     Wednesday.

     Gale Warning...LMZ261-LMZ362...6 PM Tuesday to 7 PM Wednesday.

&&

$$

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