Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 210814

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
314 AM CDT FRI OCT 21 2016

.TODAY AND TONIGHT...Forecast Confidence Is High.

A large Upper level trough axis will reach the eastern Great Lakes
this evening as a ridge pushes into the Northern Plains. Little in
the way of upper level divergence with mainly weak downward 700mb
motion.  Weak upward motion begins tonight. Weak 700 mb warm air
advection begins this afternoon, with stronger 8950 mb warm air
advection tonight.

Forecast soundings indicate the shallow moisture producing the
stratocumulus deck will thin and begin to scatter out by sunrise.
Therefor expect partly/mostly sunny skies.  Then 850/700 mb RH
increases, especially after midnight with the developing warm air

The surface ridge will move across southern Wisconsin early this
evening with weak south winds developing south central Wisconsin
late tonight.  Frost potential expected to be greatest over
southeast Wisconsin, where frost is likely, even close to lake
Michigan. Frost advisories will likely to be needed.

Lake showers may brush the far southeast Wisconsin shore areas,
especially near Wind Point and Kenosha early this morning. The HRRR
then shifts the lake band more to the east by mid/late morning.

.SATURDAY THROUGH MONDAY...Forecast Confidence...High

High pressure will bring continued mostly sunny to partly cloudy
skies Saturday. Highs temps will warm back up to around or even a
couple degrees above normal as southwest winds develop on the
back side of the high.

Weak low pressure is progged to move through the state on Sunday.
It still looks like the best forcing will remain to the north of
the surface low, so expecting the dry weather to continue. High
pressure will follow the departing low for Monday.

Should see temps several degrees above normal Sunday, falling
back to around normal Monday.

.TUESDAY THROUGH THURSDAY...Forecast Confidence...Medium

A stronger low will develop to the southwest on Tuesday, moving
through the area on Wednesday. This system is expected to bring
widespread rainfall to the forecast area Tue and Wed. The biggest
problem with this low is where exactly it will track. The GFS and
Canadian models continue to track it just to the south of the
WI/IL border. This would keep the milder temps and instability
south of the forecast area. The ECMWF is a little farther north
and would suggest a small thunder chance, so left a low end
thunder mention in the forecast.

High temperatures Tue/Wed were lowered a bit more given models
are still looking pretty cool both days, especially if a
persistent rainfall develops. Current forecast is still milder
than the blend of model 2 meter temps, so may need to lower the
temps a bit more, especially if the more southern track of the
low verifies.

Kept some low pops Thursday per the slower ECMWF solution dragging
the upper trough through. The GFS is dry though, moving the system
out faster.



Mostly VFR cigs expected. Cigs mainly between 4-5 kft in most
places. There is the potential for some MVFR cigs near Lake michigan
until mid morning.  Some Lake effect showers may brush the shoreline
areas, especially from Wind Point to Kenosha. Expect clouds
to gradually scatter out.

Surface high pressure will move across southern Wisconsin early this
evening, with mid level clouds increasing from the west late.



Brisk north winds near Small craft advisory condition from North
Point Lighthouse into mid morning due to the pressure gradient from
the low near western Pennsylvania, and high pressure over the mid
and upper Mississippi Valley.  Still the potential of 3 to 5 foot
waves until mid morning, so will extend the Small craft advisory til
10 am.

Waves will remain in the 2 to 4 foot range into the early
afternoon with 10 to 15 knot north winds.


.MKX Watches/Warnings/Advisories...
WI...FROST ADVISORY until 8 AM CDT this morning for WIZ046-047-051-

LM...SMALL CRAFT ADVISORY until 10 AM CDT this morning for LMZ645-646.



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