Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 231545 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1045 AM CDT FRI SEP 23 2016

.UPDATE...
Morning showers were associated with a weak low level jet impinging
on an 850 front draped across southern WI. They were also upstream
of a surface trough with an axis over the center of the state.
The surface trough will shift east today but the 850 features will
linger creating small chances for showers today.

&&

.AVIATION/18Z TAFS/...
Daytime mixing should bring IFR ceilings to MVFR across the region
by midday. They may linger in far southwest WI. Low level moisture
will remain through Saturday morning in south-central and southwest
WI so MVFR ceilings are likely through Saturday morning. Ceilings
may be lower in southwest WI. Eastern areas will get some drier air
from Lake Michigan this afternoon and tonight and may see VFR
ceiings at times tonight but MVFR is likely for a time Saturday
morning.

&&

.MARINE...
A surface trough will move east today and winds will become
easterly. Wind speeds and waves will approach Small Craft
Advisory levels, particularly tonight. However, confidence is not
high enough to issue at this time. A cold front will move through
the region during the latter half of the weekend, shifting winds
to the south and west with time. Wind speeds and waves look to be
below Small Craft Advisory levels.

&&

.PREV DISCUSSION... /Issued 330 AM CDT FRI SEP 23 2016/

Today and Tonight...Confidence is medium.

Low level front continues to linger just southwest of the area this
morning. Best forcing has only clipped the far southwest portion of
the area, with occasional bouts of showers and a few rumbles of
thunder. This activity will persist into the daylight hours of this
morning and will continue to focus higher PoPs across Lafayette,
Iowa and Green.

The aforementioned low level front will become a bit more diffuse
with time and gradually shift to the north this afternoon into
tonight. While we remain moist, convergence weakens and any
additional shower activity looks to become more scattered in nature
and light. Clouds will linger through the day and limit heating
potential. Highs will be right around seasonal norms for late
September.

Heading into the overnight hours tonight, a southerly low level jet
ramps up. This may lead to a redevelopment of scattered showers and
a few rumbles of thunder. Have maintained low end chance PoPs to
account for this. If model trends continue, an increase in PoPs may
be necessary.

Saturday through Sunday Night...Confidence is Medium

The main focus for this weekend is on the precipitation chances,
particularly on Sunday.

An approaching deep mid level trough will provide increasing
southerly flow ahead of it starting on Saturday. Some weak low
level warm air advection may lead to a few showers Saturday
morning though the forcing quickly weakens and shifts northward.
This should lead to Saturday being a fairly decent day with
ridging aloft in place for much of the day.

The main band of rain looks to come in on Sunday though there
still remains some differences in the timing between the ECMWF and
the NAM/GFS. The ECMWF is slower (afternoon) with bringing this
band of convection through compared to the NAM/GFS (morning) ahead
of the advancing cold front. Instability is fairly weak and skinny
on 23.00z NAM/GFS soundings due to weak lapse rates. Deep shear is
increasing with time, but appears to mainly be post-frontal. With
the deeper forcing occurring further north, severe weather is
looking unlikely due to the lacking instability and shear. With
the cold front looking fairly progressive, rainfall amounts should
stay more on the tame side at about a quarter of an inch to a half
inch.

Monday through Thursday...Confidence is Low

Going into next week, the question is with the deep trough and
whether it becomes cutoff from the upper level flow or continues
on with it. The 23.00z GFS and ECMWF show opposite solutions at
this point with the GFS cutting off the low and leaving it across
the Great Lakes through mid-week while the ECMWF quickly whisks it
away to the northeast. Too much uncertainty to know whether we end
up rainy and cooler (GFS) or dry and cooler (ECMWF).

AVIATION/12Z TAFS/...
Widespread MVFR ceilings, with occasional bouts of IFR this morning,
are expected during the next 24 hours. A few showers will be
possible through the day today, though confidence is too low to
mention at any TAF site at this time. The risk for a few showers and
an isolated thunderstorm will continue through tonight as a weak
front lifts north through the region. Improvement in ceiling heights
is possible late tonight as the front moves into central Wisconsin.
Winds will be easterly into Saturday.

MARINE...
Exiting high pressure to our northeast will result in easterly winds
through Saturday. Wind speeds and waves will approach Small Craft
Advisory levels, particularly tonight. However, confidence is not
high enough to issue at this time. A cold front will move through
the region during the latter half of the weekend, shifting winds to
the south and west with time. Wind speeds and waves look to be below
Small Craft Advisory levels.

&&

.MKX Watches/Warnings/Advisories...
WI...None.
LM...None.
&&

$$

UPDATE...Marquardt
TODAY/TONIGHT AND AVIATION/MARINE...Gagan
Saturday THROUGH Thursday...Halbach



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