Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 271634 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1134 AM CDT TUE SEP 27 2016

.UPDATE...

Aside from bringing the clouds into southern WI earlier, there are
no major changes to the going forecast. Exact timing of the showers
are more uncertain. They are due to vorticity advection and 850mb
frontogenesis. Rain showers will be intermittent between 3 and 5 pm,
and then become more widespread from 5 pm through around midnight.
Showers will taper off in coverage overnight. It will be breezy
during the day today, but winds will die down this evening as the
pressure gradient weakens with the center of the weakening surface
low sagging over Lake Michigan.

&&

.AVIATION/18Z TAFS/...

Gusty westerly winds will persist until late afternoon, then
diminish through the night. A large area of clouds associated with
upper level low pressure is expanding across southern WI late this
morning. Broken cloud bases will be around 4-5 kft this afternoon.
Cloud bases will then fall to MVFR with the onset of the rain by
around 5 pm, followed by the ceilings falling below 1 kft for the
overnight hours. MVFR vsbys will occur at times with the rain and
the low ceilings tonight.

&&

.MARINE...

A Small Craft Advisory continues until 7 pm CDT. Gusty westerly
winds will persist through the afternoon as strong low pressure
moves south across Lake Superior. The low will then weaken tonight
as it moves down Lake MI. Thus the SCA will expire at 7 pm.

&&

.PREV DISCUSSION... /Issued 435 AM CDT TUE SEP 27 2016/

Today and Tonight...Forecast confidence high.

The large occluded low near Lake Superior will continue to fill
today and tonight as it moves down Lake MI. The PVA and warm
advection at jet level along with 850 mb frontogenesis will bring
increasing shower coverage from north to south during the afternoon
with widespread showers for the evening. Some sunshine expected this
morning with high temps ranging from the upper 50s toward central WI
and middle 60s near the IL border. Lows tonight from 45-50.

WEDNESDAY - Confidence...Medium
A large circulation will spin from southern Lake MI slowly ese
towards northwest OH. the flow remains strongly cyclonic at all
levels into srn WI. This will keep cloud cover/shra and cool NE
winds in place. Per 3 hourly MOS numbers many areas are likely to
struggle to reach the 60 degree mark.

THURSDAY - Confidence...Medium
Large low shifts a bit further south though srn WI remains on nw
periphery of the circulation. Vort pattern looks elongated/sheared
so not as much forcing expected. Going with the consensus of the GFS
and ECMWF will keep the forecast area dry at this time. Only the
southeast corner would be vulnerable based on proximity to the
affects of the circulation though GFS barely clips the far se with
qpf and the ECMWF is even further southeast. Consensus says it stays
precip stays to our southeast so will stick with dry forecast. The
northeast breeze will persist though any breaks in sun will help to
send temps well into the 60s.

THURSDAY NIGHT THROUGH SUNDAY - Confidence...Medium
The GFS and GEM have trended more towards what the ECMWF had been
suggesting. A waffling and retrograding circulation. So expecting at
least a chance of shra this period as moisture and spokes of lift
get wrapped back into southern WI. There is an eastward shift
of the low center on Sunday so carrying just the small pop in
the eastern CWA per Superblend.

MONDAY - COnfidence...Medium
A trend towards mid level ridging appears likely with system far
enough to our east. The GFS keeps more of a low level easterly flow
while the ECMWF develops a sse regime which shows more pronounced
warming with the 925 thermal field. Will use Superblend guidance at
this point which may need a nudge should the ECMWF trend hold.

AVIATION/12Z TAFS/...Gusty wly winds will develop later this
morning once mixing ensues. Otherwise clouds will become broken this
afternoon around 4-5 kft. The cigs will then fall to MVFR with the
onset of the rain late this afternoon or early evening followed by
the cigs falling below 1 kft by late evening and overnight. MVFR
vsbys will occur at times with the rain and the low cigs tonight.

MARINE...A Small Craft Advisory continues until 7 pm CDT. Gusty
wly winds are expected once again today as strong low pressure
moves south across Lake Superior. The low will then weaken tonight
as it moves down Lake MI. Thus the SCA will expire at 7 pm

&&

.MKX Watches/Warnings/Advisories...
WI...None.
LM...SMALL CRAFT ADVISORY until 7 PM CDT this evening for LMZ643>646.

&&

$$

UPDATE...MRC/REM
TODAY/TONIGHT AND AVIATION/MARINE...Gehring
Wednesday THROUGH Monday...Collar



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