Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 151419 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
919 AM CDT Sun Oct 15 2017

.UPDATE...

Clouds are expected to hang on through the afternoon, diminishing
this evening and overnight. Any lingering drizzle or light rain
should wind down by late morning or early afternoon.

The ongoing forecast for temperatures today still seems
reasonable. Most places have dipped into the 40s and will likely
only recover into the low 50s this afternoon. It`ll be the coolest
day of the season thus far, especially when you factor in the
windy conditions.

&&

.MARINE...

The Gale Warning remains in effect until 4 pm this afternoon.
Might be able to downgrade to a Small Craft Advisory earlier than
that, as it appear peak winds will only be through early
afternoon. Advisory conditions would likely then continue into the
evening hours per latest forecast winds and waves.

Could see winds return to advisory levels Tue and/or Wed.

&&

.PREV DISCUSSION... (Issued 638 AM CDT Sun Oct 15 2017)

UPDATE...Patchy light rain and drizzle will continue for several
hours as upper level low pressure trof moves through eastern WI.
Not expecting any clearing until this afternoon or early evening.
Temperatures and blustery WNW will result in a much cooler day.
Strongest low level cold air advection this morning becoming
neutral this afternoon.

AVIATION(12Z TAFS)...Patchy light rain and drizzle this morning
with ceilings mostly in MVFR. Peak wind gusts of 25 to 30 knots
this morning will subside this afternoon.

PREV DISCUSSION... (Issued 340 AM CDT Sun Oct 15 2017)

SHORT TERM...

Today And Tonight...Forecast Confidence Is Medium To High.

Strong low level frontogenetical forcing producing numerous
showers over eastern CWA early this morning. Gusty winds
associated with some of these showers, perhaps as high as 40 to 45
mph. These should abate by 11-12Z or so.

Blustery southwest winds will turn to the west and then northwest
as tightening pressure gradient associated with low pressure near
GRB moves off to the east. Wind gusts for most of the morning
will be in the 25 to 35 mph range. Expect some light showers to
affect northern and possible eastern areas later this morning,
associated with upper low pressure passing through.

The winds will diminish late this morning and afternoon with
gradual clearing later this afternoon. Secondary passing weak mid-
level short wave will bring a period of mid-high clouds to the
area overnight.

The clouds along with boundary layer mixing above a shallow low
level inversion may prevent temperatures from falling into the mid
30s and widespread frost. Will continue to mention frost threat
for late tonight away from Lake Michigan, but will hold off on
issuing Frost Advisory due to uncertainties regarding clouds and
surface winds.

Monday Through Tuesday Night...Forecast Confidence Is High.

Models are in good agreement with trends during this period. They
show the 500 mb shortwave trough sliding east of the region on
Monday, with a weaker shortwave trough moving into the area later
Tuesday night. The 500 mb flow becomes zonal during this period.

Warm air advection develops over the region Monday into Tuesday,
with south to southwest winds gradually increasing with a
tightening pressure gradient. Forecast soundings are rather dry
during this period, so kept the dry forecast going. Temperatures
should warm from the upper 50s Monday into the middle 60s Tuesday.

LONG TERM...

Wednesday Through Friday...Forecast Confidence Is High.

Models remain in good agreement with trends into this period. They
have the zonal 500 mb flow on Wednesday into Thursday becoming
more southwesterly Thursday night into Friday. This is in response
to a ridge developing across the southeastern part of the country.

Gusty southwest winds within another shot of warm air advection on
Wednesday is followed by a cold frontal passage late Wednesday
night. At this point, the air column looks rather dry across the
region, so kept the dry forecast going Wednesday into Wednesday
night.

After a weak high pressure system moves through on Thursday,
south winds and steady warm air advection return for Friday. Thus,
warmer temperatures with dry conditions are expected. Highs
should rise from the upper 60s Wednesday and Thursday into the
lower 70s Friday. It may get a little warmer than that.

Friday Night Through Saturday...Forecast Confidence Is Medium.

Models begin to show some timing and placement differences with
features this far out in the forecast. The GFS and ECMWF show a
cold front sliding eastward through the region Saturday night,
with the Canadian on Saturday. Kept forecast dry for now during
this period, as the Canadian model looks to be an outlier
solution. This period still looks warm, with highs into the lower
70s once again on Saturday.

AVIATION(09Z TAFS)...

Difficult to buy the gust to 57 knots shown by KMSN at 0722Z with
only light showers in the area. No velocity signal from KMKX
doppler radar, however at the time of the wind gust, the winds
were switching from the south to the west as surface trof moved
through.

No other reports of wind gusts close to this strength with these
showers, but can believe gusts of 30 to 40 mph as they move
through. Light showers associated with low level frontogenetical
forcing wl move through eastern areas early this morning.

Otherwise, expect mostly MVFR cigs with a few bouts of IFR
gradually lifting later today. Strong wind gusts of 30 to 35 knots
possible, but perhaps as high as 40-45 knots with current band of
showers moving through.

MARINE...

Tightening pressure gradient over the near shore waters and Lake
Michigan in response to deepening low pressure near Green Bay. Low
will move across northern lower Michigan this morning, and into
the eastern Great Lakes this afternoon. Tightest pressure gradient
expected between 12z and 18z, when strongest winds expected. Few
gusts expected to climb to 30 to 35 knots, so wl continue Gale
Warning through early afternoon.

Current south to southwest winds will abruptly shift to the west
to northwest early this morning. Wind gusts likely to remain above
Small Craft Advisory criteria into the evening.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Warning until 4 PM CDT this afternoon for LMZ643>646.

&&

$$

Update...DDV
Today/Tonight and Aviation/Marine...MBK
Monday THROUGH Saturday...Wood


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