Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 070902
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
302 AM CST Thu Dec 7 2017

.SHORT TERM...

TODAY and TONIGHT - Confidence...Medium to High.

Few light snow showers and flurries will continue to affect the area
through 12Z as last vestiges of mid-level short wave trof pass
through the area.  Strongest lift associated with low-level
frontogenetical forcing has slide south of the area several hours
ago.  Any additional accumulation will be a dusting at best.  Expect
decreasing cloud trend later this morning into the early afternoon
due to weak short wave subsidence and influx of drier air in the low
to mid levels.  Some high clouds may return due to secondary much
weaker short wave currently over nrn MN/Can passing through the
area.  Backing low to mid level winds will allow slightly warmer air
to return to the area later today and tonight.  An increase in mid-
level RH will result in thicker clouds returning to the area for a
time tonight.  Atmosphere remains drier below 4k ft so wl hold off
on any flurrie mention at this time. Today`s partial sunshine will
help the temperature rebound a few degrees into the low to mid 20s
most areas, with wind chills in the single digits to low teens.

.LONG TERM...

Friday through Saturday...Forecast confidence is high.

We are expecting a quick round of 1 to 3 inches of snow Friday
evening. This will impact people who have evening plans, as roads
may become snow covered and slippery. Winds will be light while
it`s snowing, and then increase through the overnight hours as the
snow tapers off.

Snow should hold off across southern WI until early Friday
evening (6-8 pm), then spread through quickly during the evening
hours and taper off from nw to se after midnight. This is due to a
potent shortwave coupled with the left exit region of an upper jet
diving into the Upper Midwest pairing with decent low- mid layer
frontogenesis. A sufficient depth of 4000 feet of saturation
within the dendritic growth zone, along with -5 to -8 ubar/sec of
omega will lead to a period of widespread, accumulating snow.
Visibility will likely drop to 2 miles or less at times and
quickly accumulate on surfaces.

Models agree on 0.10 to 0.15 inch of QPF as the upper trough and
associated surface low pivot over Lake Michigan. Snow will be on
the drier side with ratios around 17:1. This equates to 1 to 3
inches of snow accumulation, with higher amounts east of Madison,
especially toward Sheboygan.

Light snow or flurries may linger into Saturday morning, but the
main story is the brisk northwest winds causing wind chills around
10 degrees during the day.

Sunday through Thursday... Forecast confidence is medium.

A large upper trough will keep southern WI in brisk northwest flow
until further notice. Shortwaves rounding the base of the trough
will bring rounds of light snow about every other day. Timing of
the snow is still uncertain, but one round should track through
southern WI Sunday night or Monday, and another one Tue nt into
Wed. Each could bring 1 to 3 inches.

&&

.AVIATION(09Z TAFS)...Brief period of MVFR cigs possible early
this morning with passing light snow showers and flurries. Most of
the forecast period will be VFR as drier air settles in behind
exiting low level trof. Some lower VFR clouds will likely return
to the area later today and this evening ahead as slightly warmer
air returns to Wisconsin. Gusty winds are again expected today,
but the gusts will remain mostly below 20kts.

&&

.MARINE...Will continue Small Craft Advisory until 12Z.
Racine Reef observing platform continuing to record gusts of 20 to
25 knots last several hours.  Gradual decrease in gusts is expected
through the morning. Possible a few gusts up to 25 knots could
linger beyond 12Z, but with decreasing trend, will forego extension
of SCA at this time.  Winds will remain breezy from the WNW today
and then shift to the WSW tonight.  Gusts could reach Small Craft
levels once again tonight ahead of an approaching cold front.
Several passing low pressure systems will result in periods of gusty
winds over the weekend.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory until 6 AM CST early this morning for
     LMZ643>646.

&&

$$

Today/Tonight and Aviation/Marine...MBK
Friday through Wednesday...Cronce



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