220 
FXUS63 KMKX 070902
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
402 AM CDT Mon Sep 7 2020

.SHORT TERM...
(Issued 358 AM CDT Mon Sep 7 2020)

Today and Tonight:

Cooler temperatures are moving in behind the front this morning
with quiet, but cloudy conditions expected through most of the 
day today. This front will return to us this evening as it gradually
make its way northward with winds shifting to the northeast and 
becoming breezy. Precipitable water values will also increase as 
the front pushes northward with mid level frontogenesis developing
along the temperature gradient. This could cause some showers and
even a few thunderstorms to develop during the early evening. 
Better chances arrive after midnight as we move into southwest 
flow at 500mb and positive vorticity advection streams over the 
area. We'll even have some support with the right entrance region 
of the upper level overhead. There is some elevated instability 
as CAPE values will be around 800 J/kg, so can't rule out some 
embedded thunderstorms overnight.

RAH

&&

.LONG TERM...
(Issued 358 AM CDT Mon Sep 7 2020)

Tuesday through Sunday:

The start of the long term period is going to feel more like a
late September into early October pattern than early September
with highs in the low to mid 50s and rain. Breezy northerly winds
will accompany the cooler temps and make it feel like a pretty raw
day compared to what we've been used to. All of this is the result
of a stalled frontal boundary to the south and a digging trough in
the western US that also extends NE into southern Canada. Multiple
weak waves eject out of the digging trough and move NE across the
region Tue/Wed. This synoptic forcing will combine with
frontogenesis and WAA aloft to bring an extended period of light
to moderate rain with some embedded thunderstorms. Precip should
start tonight and continue for the most part through Wednesday
night. Forecast QPF amounts from various models have backed off 
slightly from previous versions and between 1 to 2 inches is 
expected from Monday through Wednesday night. Forecast soundings 
do show some elevated instability through the period and we could 
see enhancement of amounts from any thunderstorms that develop. 
These occurring over a more spread out period of time should limit
any threat for flooding. 

The trend in models of cutting off the digging trough in the Four
Corners region has held and will provide some relief from the 
cooler, rainy, and breezy days by Thursday. Surface high pressure
builds to the north and we'll see some brief ridging aloft as the
cut off low begins to shift east. Highs on Thursday could reach
back into lower 60s. The high kicks east Friday with winds
shifting to the south bringing more seasonable temperatures back 
to the southern WI. 

There is good agreement in the system opening up and moving across
the region Friday night through Saturday. Increasing WAA ahead of
this low will bring better moisture northward and a round of
thunderstorms is expected as the low swings through. While winds
do shift to the north behind this system we shouldn't have much of
an airmass modification and highs for Sunday stay seasonable. 

Stumpf

&&

.AVIATION...
(Issued 358 AM CDT Mon Sep 7 2020)

Northwest winds will gradually become lighter as we head through
the morning hours. Winds will then shift to the northeast and
become gusty along the lake this evening. These northeast winds
will continue into Tuesday afternoon with gusts around 25 knots
across much of southern and eastern Wisconsin.

VFR ceilings are expected through most of the day today with
ceilings gradually decreasing to MVFR to IFR values overnight
tonight. Along with low ceilings rain with a few embedded
thunderstorms will be possible mainly after midnight and continue
through Tuesday.


RAH

&&

.MARINE...
(Issued 358 AM CDT Mon Sep 7 2020)

Northwest winds will gradually become lighter and drop below Small
Craft Criteria this morning. Winds will then shift to the
northeast with gusts around 30 knots tonight into Tuesday. An
additional Small Craft Advisory is likely tonight through Tuesday
night. Waves tonight will build to 4 to 8 feet and continue
through Tuesday night.

RAH

&&

.BEACHES...
(Issued 358 AM CDT Sun Sep 6 2020)

Brisk northeast winds will develop tonight causing waves to build
to 4 to 7 feet into Tuesday night. This will lead to high swim
risk conditions as life threatening waves and currents are 
expected.

RAH

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 9 AM 
     Monday.

&&

$$

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