Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 280451
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1051 PM CST Mon Feb 27 2017

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Tuesday
Issued at 224 PM CST Mon Feb 27 2017

The latest rap analysis and satellite/radar imagery show yesterdays
cold front returning northward from the Upper Peninsula to the
Dakotas early this afternoon.  Winds have turned to the southwest
aloft as shortwave energy moves east across the western conus, and
are pushing mid and high clouds across the northwest half of
Wisconsin. Starting to see light returns showing up over southwest
Iowa and northwest Missouri, which is the leading edge of the deeper
moisture return.  As this moisture lifts northeast into the state
late tonight, precipitation timing and potential for snow/freezing
rain are the main forecast concerns.

Tonight...Southwest winds will increase aloft ahead of the next
shortwave trough, and associated cold front that will move southeast
across the northern Plains and into the northern Mississippi Valley
by daybreak.  Ahead of the front, will see a push of deeper moisture
accompanied with mid-level fgen which should produce a swath of
precipitation over Iowa/Minnesota during the evening before entering
Wisconsin overnight.  This precipitation is on track to arrive over
central and east-central WI between 06-09z, and across northern WI
between 09-12z. Though temperatures will not fall much tonight, the
combination of readings near freezing over north-central WI and
pavement temperatures below freezing will lead to light
accumulations of snow/freezing rain from the onset of precip through
8 am, including the morning commute. Will issue a sps to provide a
heads up for the north. Elsewhere, precipitation should consist
mostly of rain. Lows should fall into the upper 20s over northern
WI, to the mid 30s in central WI.

Tuesday...The swath of precip will continue to lift to the northeast
and exit northeast WI during the morning.  Progged soundings
indicate that mid-levels temporarily dry out behind this leading
swath of precip, but look to remain saturated enough for periods of
drizzle to occur thereafter.  As the front moves across the eastern
half of the state and a wave of low pressure lifts into southern WI
during the afternoon, there is potential for more widespread light
rain to impact the area.  Highs will be warmer than todays readings
thanks to the push of warm air, and should range from near 40 in the
north to the middle 40s in the south.

.LONG TERM...Tuesday Night Through Monday
Issued at 224 PM CST Mon Feb 27 2017

Precipitation type for Tuesday night into Wednesday morning
continues to be the primary challenge for the long term forecast.
Rain is expected to continue across the Fox Valley and central
Wisconsin while snow showers and possible freezing drizzle press
into northern Wisconsin. A transition to snow in the north is
anticipated to be complete by early Wednesday morning, but drying
mid levels around midnight may keep freezing drizzle in a little
longer as ice crystal introduction into the lower levels
diminishes during this time and liquid precipitation freezes to
colder road surfaces. The rest of the region will then also change
over to snow through the day and into the afternoon with a brief
period of slick road conditions possible as road surfaces drop
below freezing. Pops will gradually diminish through the day and
into the afternoon before the system moves out by the evening.

Northwesterly flow, wrap around moisture, and a couple shortwaves
aloft will bring in a couple additional chances to see some light
snow primarily in northern Wisconsin, but also sporadically
through the Fox Valley and central Wisconsin through Thursday. A
weak ridge is expected to move into the region Friday morning
which will bring in a brief quiet period and colder temperatures
overnight. Warm air advection returns ahead of the next shortwave
Friday night, for another brief round of possible snow showers
ahead of the next ridge that sits in the area for the weekend.
Models then show a strengthening surface low pressure system that
will enter the region late Sunday night into Monday with another
round of possible mixed precipitation as temperatures rise ahead
of its arrival, although the timing and placement of this system
are still highly uncertain this far out.

High temperatures will be around normal through the rest of the
work week before advancing warm air advection brings temperatures
well into the 40s over the weekend.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1036 PM CST Mon Feb 27 2017

Conditions will deteriorate rapidly overnight as an approaching
frontal system approaches the area from the southwest, bringing a
band of precipitation from southwest to northeast. Light snow
and/or freezing rain may occur for a few hours over north-central
Wisconsin late tonight into early Tuesday morning, which could
impact flat surfaces such as runways. A period of low level wind
shear conditions is also possible late tonight over north-central
Wisconsin. LIFR/IFR cigs and poor vsbys are expected to hold tough
through much of Tuesday and Tuesday evening with periods of light
rain and drizzle. The rain may mix with or changeover to snow
across north-central Wisconsin Tuesday evening.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....MPC
LONG TERM......Uhlmann
AVIATION.......Kurimski


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