Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 201155 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
655 AM CDT Wed Sep 20 2017

.UPDATE...

Have trimmed back precip chances a bit for this morning, as it
appears the upstream line of storms may go largely north of the
forecast area. Latest radar does show the line building southward
a bit, so did feel the need to leave some pops in there.

&&

.AVIATION(12Z TAFS)...

Fog in the east will improve by not long after sunrise this
morning. The upstream line of storms will diminish as it moves in
from the west this morning, with more storms likely later this
afternoon and evening as a cold front moves into the area.

VFR conditions are expected today after the fog diminishes, other
than briefly lower visibilities in thunderstorms. Could see some
low clouds develop tonight with the front stalled in the area.

&&

.PREV DISCUSSION... (Issued 344 AM CDT Wed Sep 20 2017)

SHORT TERM...

Today and tonight...Forecast confidence is medium to high:

Fog in the east will likely persist through the early morning
hours given light winds and limited cloud cover. Visibilities
should improve not too long after sunrise as daytime mixing kicks
in.

Low pressure will drag a cold front into the forecast area by this
evening, with the front hanging up over the southeast tonight.
Plenty of moisture and instability ahead of this front, but
forcing is not that impressive. Still, should be enough for a
chance for showers and storms.

Current line of storms upstream will likely diminish as it enters
the forecast area from the west this morning. Next round of storms
will then develop during the afternoon as the front approaches the
area. Given the lack of forcing and system dynamics, the
shower/storm activity will largely diminish by late evening as
daytime heating is lost, though could see a shower/storm at times
overnight with the front hanging around.

Temps today and tonight will be well above normal for this time of
year, likely only falling short of records by a few degrees this
afternoon.

Thursday...Forecast confidence is medium:

The stalled cold front will continue to weaken across southern
Wisconsin Thursday morning. We`ll be beneath large scale ridging
aloft, so there will be virtually no support for lift other than
the weakening front. Despite this weak convergence and some
lingering low level moisture, morning showers do not look likely.
Chose to leave Thursday morning dry for now, but that may need to
change once we see how much oomph the front has overnight.

Winds will quickly shift back around to the south by late Thursday
morning, which will help temperatures recover quickly from the
fropa. There will again be some weak low-level convergence with this
wind shift, but the column will be even drier, so I`m sticking with
a dry forecast on Thursday afternoon and evening. Those southerly
winds will also allow for the dew points to recover quickly,
potentially setting the stage for some low clouds over and near the
lake.

LONG TERM...

Friday through Wednesday...Forecast confidence is medium:

A very slow moving upper level ridge will remain in place through
much of the period. This will keep high pressure and unseasonably
warm temperatures in place across much of Wisconsin. A baroclinic
zone on the western flank of the ridge will very slowly approach
southern Wisconsin through the period. By early next week, it looks
like that front will reach southern Wisconsin, bringing chances for
precip late on Monday and especially on Tuesday. Given the
abnormally high temperatures and dew points, thunder will be
possible each day despite modest lapse rates.

AVIATION(09Z TAFS)...

Fog in the east will improve by not long after sunrise this
morning. The upstream line of storms will diminish as it moves in
from the west this morning, with more storms likely later this
afternoon and evening as a cold front moves into the area.

VFR conditions are expected today after the fog diminishes, other
than briefly lower visibilities in thunderstorms. Could see some
low clouds develop tonight with the front stalled in the area.

MARINE...

Breezy south to southeast winds will likely gust to 25 knots at
times in the northern forecast zones, so decided to issue a Small
Craft Advisory north of Port Washington for this afternoon into
evening. Waves will also be upwards of 4 feet in this area.

Lighter winds and lower waves are expected for the remainder of
the week.

BEACHES...

Breezy south to southeast winds will likely build waves around 4
feet today at beaches in Sheboygan and Ozaukee counties, thus a
Beach Hazard Statement will be issued. The highest waves and
strongest currents are expected this afternoon into the evening.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Dense Fog Advisory until 9 AM CDT this morning for WIZ052-059-
     060-065-066-071-072.

     Beach Hazards Statement from 1 PM CDT this afternoon through
     this evening for WIZ052-060.

LM...Small Craft Advisory from 1 PM this afternoon to 9 PM CDT this
     evening for LMZ643.

&&

$$

Update...DDV
Today/Tonight and Aviation/Marine...DDV
Thursday THROUGH Tuesday...BSH



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