Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 262021
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
221 PM CST Sun Feb 26 2017

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Monday
Issued at 220 PM CST Sun Feb 26 2017

The latest rap analysis and satellite/radar imagery show a shortwave
trough moving east towards the western shoreline of Lake Superior
while pushing a cold front across northwest Wisconsin.  A band of
snow showers is accompanying the front, with some decent returns
moving towards western Vilas county.  Will issue an SPS if snow
showers hold on to their current intensities and forward motion.
These snow showers will pass across north-central WI late this
afternoon, and the heaviest snow showers could drop a quick inch of
snow.  Behind the front, skies clear over northern Minnesota, but
more mid and high clouds are heading our direction over the western
Dakotas.  Snow shower trends is the main forecast concern through
this period.

Tonight...The cold front that is moving into northwest Wisconsin is
expected to stall over central WI by late tonight.  But as shortwave
energy peels off to the northeast and mid-level heights build,
convergence along the front will weaken, which should lead to snow
showers diminishing along the front over far northern Wisconsin this
evening.  Less than a half inch of additional accumulations are
expected. Thereafter, mid and high clouds will invade from the west
as winds become light. Because of the mid and high clouds overhead,
think fog potential is rather limited.  Lows falling into the single
digits in the north, and into the teens to lower 20s elsewhere.

Monday...Winds turn to the south which will cause the front to
return northward through the day.  Will continue to see broken mid
and high clouds overhead, thicker across the north, but low level
moisture looks too meager for any chance of precip along the front.
More mild air will accompany the southerly winds, which should boost
highs into the mid 30s in the north to middle 40s in the south.

.LONG TERM...Monday Night Through Sunday
Issued at 220 PM CST Sun Feb 26 2017

A weak surface ridge will persist into the overnight hours of
Tuesday before giving way to an approaching low pressure system
and associated upper level trough. Strong warm air advection
ahead of this system will allow rain to fall across the Fox Valley
when this system arrives with a narrow band of mixed
precipitation further north and snow in northern Wisconsin. The
exact placement of this transition zone may still vary, but as the
morning progresses and warm air continues to flow into the
region, wintry precipitation is expected to steadily shift to the
north as precipitation transitions to rain by the early
afternoon. Rain showers will then continue into the evening as the
surface system moves across the region.

Cold air advection returns overnight Tuesday into Wednesday,
bringing back a chance of wintry mix and snow. Much of Wednesday
will then feature smaller chances for additional precipitation as
the trough drags off to the east and leaves behind enough forcing
to continue active weather along the lakeshore and Fox valley.
Northern Wisconsin will also have a few snow showers during this
time as wrap around moisture enters from the north.

A brief, mostly dry period is in store for Thursday into Friday
as the next surface high pressure system moves in under an upper
level ridge. A few snow showers are possible in northern Wisconsin
as winds shift northwest. Friday into Saturday will then see the
next period of light snow showers as a shortwave riding along the
back edge of this ridge enters the region into Saturday. A
stronger low pressure system follows as an upper level trough
moves in Saturday into Sunday, but the placement of this system
is still highly uncertain this far out.

Temperatures during this period will be largely above normal
through Tuesday afternoon before a cooling trend through the rest
of the week as the ridge and high pressure system move into the
area. Temperatures then start to rise above normal once again
through the weekend as winds shift south Saturday.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1107 AM CST Sun Feb 26 2017

The combination of a weak front dropping into northern Wisconsin
and an unstable air mass  will lead to scattered snow showers
over northern Wisconsin into this evening. The snow showers may
briefly be moderate to heavy with ifr conditions. Elsewhere, vfr
cigs are anticipated through this evening with a gusty southwest
wind. The front will weaken tonight, and snow showers will
diminish across northern WI. Mid and high clouds will arrive late
tonight, but no precipitation is expected through the rest of the
taf period.
&&

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

$$

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


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