Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 060312
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
912 PM CST Mon Dec 5 2016

.UPDATE...

A strong low level inversion around 1100 feet should keep stratus
in place. With increasing southeast flow visibilities will drop,
but at this moment should not be widespread enough for dense fog.
Somewhat higher potential for this is west of Madison.

&&

.AVIATION/06Z TAFS/...

RAP Soundings show moisture trapped beneath a strong inversion
around 1100ft sticking around through the night, so expect
IFR/LIFR stratus to persist. Expect visibilities to drop a bit,
with LIFR vsbys mainly west of Madison. Winds along the lake will
pick up slightly and become southeast tonight which may help raise
ceilings and visibilities somewhat, mainly in the east. A cold
front will come through on Tuesday bring stronger west winds and
this should help scour out low clouds somewhat during the
afternoon.

&&

MARINE...

Brisk south winds are expected tonight, reaching Small Craft
Advisory levels in gusts north of Port Washington. There will be
a lull in winds Tuesday morning as a cold front moves through.
Then winds will become westerly and increase to Small Craft
Advisory levels once again later on Tuesday. All zones are
expected to reach advisory criteria at this time and these strong
winds could persist through Thursday. Think waves will stay below
4 feet during this period due to the westerly flow.

&&

.PREV DISCUSSION... /Issued 320 PM CST Mon Dec 5 2016/

SHORT TERM...

TONIGHT and TUESDAY...Forecast confidence is high.

High pressure to the southeast will continue to move away from
the region as low pressure moves across MN. Winds stay 5 to 10
knots overnight with this pressure gradient, but due to the low
level moisture in place and fresh snow, it looks like fog will
stick around thorough the night. Soundings show moisture trapped
beneath an inversion around 1000ft. It may be dense in some spots
late tonight and Tuesday morning. Fog will create slippery
conditions on untreated roads with temperatures near or below
freezing.

The cloud cover may stick around through Tuesday. An upper low moves
across MN with sheared vorticity brushing the northern CWA. During
the day a cold front moves through. Behind it winds will be brisk
out of the west. There is a small chance for freezing drizzle and
snow north and west of Madison in the morning. The GFS shows a
partial loss of ice crystals resulting in freezing drizzle while the
NAM shows snow.

LONG TERM...

TUESDAY NIGHT THROUGH FRIDAY... Forecast confidence is medium.

Winds will be picking up out of the west Tue night as cold air
advection ensues. Lows will drop down to around 20 with a possible
window of time with clear skies toward WI border due to weak ridging.

The brisk west winds and cold temperatures will be the main story
for the latter half of the week. Models are now in good agreement on
the location of a closed upper low sliding across Ontario Canada
though Wed and into Ontario on Thu.

An upper jet will strengthen over the Midwest Thu morning which will
produce some upward motion over southern WI. This combined with the
500mb trough and surface trough could lead to some light scattered
snow showers or at least flurries in srn WI.

The coldest air will drop into southern WI on Friday with 850 mb
temps around -14C. Highs will be in the 20s Wed and Thu... then
struggle to reach 20 on Friday. Lows will be in the teens each night.

SATURDAY THROUGH MONDAY... Forecast confidence is low.

We will get into more of a zonal flow pattern for the weekend. A
ripple in the flow will bring a weak surface low through the Upper
Midwest/Great Lakes on Saturday.  This feature now looks very light
on the ECMWF and GFS, but the Canadian model is still painting
higher qpf with a much more amplified system.

The GFS and ECMWF are now showing their more amplified system
crossing WI on Sunday. This bears watching for the potential of
accumulating snow.

AVIATION/00Z TAFS/...

Soundings show moisture trapped beneath an inversion around 1000ft
sticking around through the night, so expect low stratus to persist.
Winds along the lake will pick up slightly and become southeast
tonight which may help raise ceilings and visibilities somewhat,
mainly in the east. Given current trends, confidence is low in
this happening. A cold front will come through on Tuesday bring
stronger west winds and this should help scour out low clouds
somewhat during the afternoon.

MARINE...

Brisk south winds are expected tonight, reaching Small Craft
Advisory levels north of Port Washington. There will be a lull in
winds Tuesday morning as a cold front moves through. Then winds will
become westerly and increase to Small Craft Advisory levels once
again later on Tuesday. All zones are expected to reach advisory
criteria at this time and these strong winds could persist through
Thursday. Think waves will stay below 4 feet due to the westerly
flow.


&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...SMALL CRAFT ADVISORY until 6 PM CST Wednesday for LMZ643.

&&

$$

UPDATE...Hentz
TONIGHT/Tuesday AND AVIATION/MARINE...Marquardt
Tuesday NIGHT THROUGH Monday...MRC


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