Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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867
FXUS63 KMKX 212249
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
549 PM CDT Fri Sep 21 2018

.UPDATE...

Look for the low level cold air advection stratocu to continue
clearing from northwest to southeast this evening. Winds will veer
to the northeast over Lake Michigan later tonight. The combo of
the cold temps and warm lake will result in some lake effect
clouds spreading into southeast Wisconsin between after 4 am
Saturday. These clouds will be progressive and eventually push out
of the area by late morning.  The forecast is on track.

&&

.AVIATION(00Z TAFS)...

VFR conditions will continue through much of the TAF period. As
winds turn to the northeast late tonight, after 09z Saturday, we
could see some lake effect clouds spill into KENW/KMKE/KUES
throughabout 16-17z Saturday. They could be MVFR CIGS around
2.5-3kft. They will be progressive and move out of southeast
Wisconsin by late morning. Light winds and radiating temperatures
could result in some patchy dense fog north and west of Madison
overnight.

&&

.PREV DISCUSSION... (Issued 328 PM CDT Fri Sep 21 2018)

DISCUSSION...

Tonight and Saturday...Forecast confidence is high.

Brisk wnwly winds and cold advection will weaken tonight. High
pressure over the Great Plains will move to central and srn WI
late tnt. Mostly broken stratocumulus will diminish during the
early evening hours. Then clear and cool for tnt, although lake
effect clouds are expected to develop after 09z over far se WI via
nely flow. The opportunity for light rain showers is brief and may
focus more in ne IL so will not mention any chances at this time.
Skies will become mostly sunny for the afternoon. High temps in
the 60s over all of srn WI.

Sunday and Monday - Confidence...Medium
The influence of the surface high gradually wanes while a
southerly flow regime sets up Sunday night into Monday. Some of
the models are showing a little qpf due to increased moisture
transport. All in all mid level forcing will remain west as will
lower level convergence associated with approaching trough.

Monday night and Tuesday - Confidence...Medium
Lower level forcing will be on the increase with the approach and
passage of surface/850 front. There will be a gradual increase in
broad cyclonic vorticity as mid level trough axis translates east
from MN/IA. Looks like a fairly decent shot at some rain moving
in Monday night and lingering into at least Tuesday morning. A
rumble of thunder is possible though soundings look overall devoid
of much in the way of CAPE.

Wednesday - Confidence...Medium
Shot of some CAA as low level thermal trough looks rather
transient. Still, some single digit celsius 850 temps with this.
Influence of this feature to last into Wednesday night though a
shift towards a WAA regime noted.

Thursday and Thursday night - Confidence...Medium
Another 500 millibar trough will swing through. This one looks a
bit more vigorous than the previous one, however instability looks
limited. The surface low will track to our north with an
associated cold front swinging through Thursday night.

Friday - Confidence...Medium
Surface high proggd to gradually work into the area with overall
quiet conditions.

AVIATION(21Z TAFS)...Wnwly wind gusts 25-30 kts diminishing by
sunset. Bkn035-040 stratocumulus diminishing early this evening.
However, lake effect clouds bkn020-030 will develop over far se
WI for 09z-16z Sat with clearing afterward. Fog expected early
Sat AM in the WI River Valley.

MARINE...A Gale Warning remains in effect through 7 PM for the
nrn two thirds of the lake and has been extended until 11 PM for
the northeast portion of the lake. Strong low pressure will
continue newd across nrn Quebec through tnt. The pressure
gradient will slacken tnt as high pressure moves from the nrn
Great Plains into central WI into Lower MI. The high waves will
gradually subside tonight into Sat AM.

Over the nearshore waters of se WI, a Small Craft Advisory is in
effect north of North Point Lighthouse into the early evening for
gusty nwly winds, while in effect until 7 AM south of Port
Washington for gusty winds and high waves. The winds and waves
will be much lighter for Saturday and Sunday.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Warning until 7 PM CDT this evening for LMZ669-671.

     Small Craft Advisory until 7 AM CDT Saturday for LMZ645-646.

     Small Craft Advisory until 9 PM CDT this evening for LMZ643-644.

&&

$$

Update...Davis
Tonight/Saturday and Aviation/Marine...Gehring
Saturday Night through Friday...Collar



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