Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 181445
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
945 AM CDT Sat Mar 18 2017

.UPDATE...Updated sky grids to delay any appreciable clearing
until this evening. Back edge well west into wrn IA and extreme sw
MN so would have to hope for some holes to evolve to see any sun
today. Soundings not overly impressive for this so have trended
more pessimistic in the sky grids today. Going temps may be a
smidge too warm in the absence of any breaks in the clouds.

PC

&&

.MARINE...Going Small Craft Advisory still looks good until noon.
Only seeing isolated gusts 20 knots plus at the moment so expect
the noon time to hold with fewer gusts upstream with the
slackening gradient.

PC

&&

.PREV DISCUSSION... (Issued 656 AM CDT Sat Mar 18 2017)

AVIATION(12Z TAFS)...Rain and snow showers continue to diminish
across southeast WI. A few flurries and sprinkles remain until 14z
or so. Otherwise, MVFR cigs to continue most of the day. Thinning
of the clouds and eventual breakup is expected late today into
tonight. Some fog may develop late tonight in light winds and at
least partial clearing.

PREV DISCUSSION... (Issued 331 AM CDT Sat Mar 18 2017)

SHORT TERM...

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

Latest water vapor imagery showing circulation associated with upper
low over northern WI shifting slowly southeast.  This feature has
been driving some scattered mostly rain showers across southern WI
since evening, however as colder air continues to filter into
southern WI, some of the rain showers have changed over to a mix or
all snow.  KUNU vsby briefly reduced to 3/4 mile in a passing 25-30
dbz shower.  These rain and snow showers will affect eastern half of
CWA through 12z.  Weak returns upstream have been diminishing so wl
go dry after 12z, but possible a few flurries or sprinkles may hang
on in the east for an hour or two. Otherwise, expect clouds to
persist this morning, possibly eroding in the west during the
afternoon and in the east in the evening. Thermal trof and upper
level jet does shift off to the east later today as low level
moisture gradually scours out.  Passing high pressure ridge axis and
light boundary layer winds will allow temperatures to fall quickly
later in the night if expected clearing does take place. This may
result in some patchy late night fog.  Due to uncertainty of cloud
cover, wl limit fog to patchy wording and only in the late night
hours for now.

LONG TERM...

SUNDAY AND MONDAY... Forecast confidence is medium.

Ridging with southerly flow will keep southern WI mild and dry
during the day Sunday. Look for highs in the lower 50s well inland,
but lower 40s near the lake due to southeast winds.

Sunday evening, showers may develop along an elevated warm front.
The better chances for precip will be across northern WI closer to
the occlusion and south of the WI/IL border where there should be a
nose of a low level jet. Showers become likely across southeast WI
as the surface trough/ cold front reach the area overnight Sunday
night.Model soundings show elevated instability, so if any showers
develop, there could be a rumble of thunder during the late evening
and overnight.

The cold front is expected to clear southeast WI by Monday morning
and cooler air will begin pouring in on dry northwest winds.

TUESDAY AND WEDNESDAY... Forecast confidence is high.

High pressure with dry weather will dominate these two days. High
temperatures in the 40s to upper 30s are expected, with lows in the
20s.

THURSDAY THROUGH SATURDAY... Forecast confidence is low.

Southerly flow with return flow around the high will usher moisture
back into southern WI by Thu evening. Precip associated with this
warm front will likely be in the form of rain, although there is a
question of how quickly surface temps will warm Thu night, so kept
the mention of snow.

Southern WI will be well into the warm sector on Friday. The weather
pattern favors thunderstorms over much of the Midwest ahead of a
deep low over the Plains. This will be a time period to watch for
the risk of severe weather.

Then the surface low will track through Illinois or southern WI,
depending on the model. The track will determine winds and precip
type for southern WI next weekend.

AVIATION(06Z TAFS)...Brisk nwly winds are expected for early Sat
AM into the early afternoon hours. Stratus clouds mainly in the
MVFR range will prevail for the morning hours and will lift to
3.5-4.0 kft for the afternoon. The stratus clouds will gradually
become scattered from west to east across srn WI during the
afternoon and early evening.

MARINE...

Tightening pressure gradient behind low pressure moving southeast
across Michigan will result in increasing northwest winds early this
morning.  Gusts to 25 knots are still expected so the current Small
Craft Advisory will remain in effect.  The Small Craft is set to
expire at noon, but may need to be extended into the afternoon.
Otherwise, winds and waves will slowly subside as high pressure
ridge approaches the western Great Lakes late today and tonight.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory until noon CDT today for LMZ643>646.

&&

$$
Today/Tonight and Aviation/Marine...MBK
Sunday THROUGH Friday...Cronce



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