Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 070317
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
917 PM CST Tue Dec 6 2016

.UPDATE...

Skies may clear briefly near the Illinois border tonight, but then
fill in as moisture is trapped beneath an inversion that gradually
lowers. The new NAM does dry the layer around 3 thsd ft, but
moistens the 2 thsd ft layer, so Wednesday looks fairly cloudy.

&&

.AVIATION/06Z TAFS/...

Skies may clear briefly near the Illinois border tonight, but then
fill in as moisture is trapped beneath an inversion that gradually
lowers. The new NAM does dry the layer around 3 thsd ft, but
moistens the 2 thsd ft layer, so tonight and Wednesday looks
fairly cloudy with mainly MVFR cigs.

&&

MARINE...

brisk west winds due to strong low pressure near lake Superior.
The low will gradually weaken Wednesday. Some peak gusts reaching
the 30kt range tonight. The highest waves will likely be out
toward the open waters of Lake Michigan. Due to these high winds
and waves, a small craft advisory is in effect through tomorrow.

&&

.PREV DISCUSSION... /Issued 259 PM CST Tue Dec 6 2016/

SHORT TERM...
TONIGHT and WEDNESDAY...Forecast confidence is high.

A cold front is pushing its way through eastern Wisconsin at the
moment with a brief band of drizzle/light snow ahead of it.  Behind
the front, colder air is moving in with a brief dry slot leading to
a 1-3 hour window of clearing before more low clouds funnel in
behind.  The main question for tonight into tomorrow is with cloud
cover and how overcast we may be.  Currently...the fog IR band shows
an expansive band of stratus moving down across Minnesota/western
Wisconsin which is expected to make it into southern Wisconsin this
evening.  Some of the meso-models are showing this stratus making it
down to the IL border while the other handful of them are keeping
skies a bit more clear tonight.  I went with a blend of this with
keeping things a bit cloudier behind the clear wedge but then
improving later on tonight with less clouds to the south.  If some
of the clouds do remain into tomorrow, the saturated layer would end
up in the ice growth zone and could lead to some flurries.
Confidence is not high in this scenario given the subsidence in
place, so will keep it out of the forecast for now.

WEDNESDAY NIGHT through THURSDAY...Forecast confidence is high.

Upper level trough pushes through the region through the
period...though much of the moisture remains to the north of the
region and only flurries will likely be possible...especially
during the late morning through early evening Thursday. Modest
northwest winds and substantial cloudiness will remain through
the majority, if not all, of the period with below normal
temperatures.

LONG TERM...
FRIDAY through TUESDAY...Forecast confidence is high.

Fairly zonal flow across the northern tier of the US to start the
period as large surface high pushes just to the south of the
region friday into Saturday...may actually see some sunshine on
Friday. Modest warm advection pattern sets up for Saturday into
early Sunday as the surface high moves off towards the east coast
and an area of low pressure develops over the plains. Snow likely
to develop later Saturday afternoon into the evening hours...only
modest differences in timing between the Euro and GFS. Snow may
become moderate at times during the evening into the overnight as
the lift looks to be close to sweet spot in the snow growth
region...not a huge system by any definition but something to
watch with at least advisory level amounts likely if everything
holds as is in the current runs. Will have to watch the warm nose
on late Saturday/early Sunday...if it moves just a bit further
north it could throw a wrench in the whole forecast. Snow should
wrap by late Sunday afternoon or early evening at the extreme
latest...colder air behind the system for Monday. Another fast
moving system Tuesday may drop some light snow...much much much
colder air possibly loading up for the middle of next week. Stay
tuned on first possible Arctic air intrusion.

AVIATION/00Z TAFS/...
Winds have shifted as a cold front has moved through the region
which is bringing an end to the IFR/LIFR conditions.  After a brief
clear patch in the clouds, another round of MVFR ceilings will move
in from the northwest with heights around 2kft.  These ceilings are
expected to linger into the evening before possibly clearing late.
Will have to keep an eye on whether or not the low cigs can continue
into tomorrow afternoon as well since conditions will not change
much.

MARINE...
Winds have shifted to the west as a cold front has pushed through
with gusty winds beginning along the nearshore zones.  These gusty
conditions will continue into tomorrow with some peak gusts reaching
the 30kt range. The highest waves will likely be out toward the open
waters of Lake Michigan.  Due to these high winds and waves, a small
craft advisory is in effect through tomorrow.

MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...SMALL CRAFT ADVISORY until 10 AM CST Wednesday for LMZ644>646.

     SMALL CRAFT ADVISORY until 6 PM CST Wednesday for LMZ643.

$$

TONIGHT/Wednesday AND AVIATION/MARINE...Halbach

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...SMALL CRAFT ADVISORY until 10 AM CST Wednesday for LMZ644>646.

     SMALL CRAFT ADVISORY until 6 PM CST Wednesday for LMZ643.

&&

$$

UPDATE...Hentz
TONIGHT/Wednesday AND AVIATION/MARINE...Halbach
Wednesday NIGHT THROUGH Tuesday...ABS


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