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Area forecast discussion 
National Weather Service Green Bay WI
257 PM CDT sun Mar 29 2015

Forecast discussion for routine afternoon forecast issuance

Synopsis...
issued at 256 PM CDT sun Mar 29 2015

Pretty typical late March weather with temperatures undergoing
considerable day to day variation.

The large scale will have modest amplitude most of the period as
progressive and quite energetic band of westerlies remains across
much of the Continental U.S. And southern Canada. The lack of amplitude on the
large scale will result in temperatures rollercoastering around
normal with the passage of each weather system. There will be enough
opportunities and sufficient available moisture for precipitation that
amounts are likely to end up near normal for the period.
&&

Short term...tonight and Monday
issued at 256 PM CDT sun Mar 29 2015

Main forecast concern through Monday will be the chance for light
rain Monday afternoon...which will carry over into Monday night.

After a complicated system today with a Kitchen sink of different
precipitation types...quieter weather returns tonight. The frontal
system that brought todays weather should exit the state around 00z
tonight. This will bring precipitation to an end in most locations...with
northern Wisconsin seeing some lingering light lake effect snow
showers for a few hours this evening. With drier midlvl air and
upper level ridging pushing in behind this system...clouds will clear
tonight. Current satellite imagery shows this clearing in eastern
Minnesota now...and after timing its arrival most of northeast
should see mostly clear skies by midnight. Again...northwest flow
off of Lake Superior will mean continued cloud cover in northern
Wisconsin per the usual through much of the night.

Monday will start off quiet...with mostly sunny skies and dry
conditions. Models then have a weak shortwave and an upperlvl jet
move into the Great Lakes region Monday afternoon into Monday
night. Clouds and precipitation chances should increase Monday after
18z...but as the norm with weaker impulses in the mean flow...models
are having issues agreeing on a solution as these features slide
southeast. Seems the track of the precipitation is a bit south and slower
than previous runs...so attempted to capture this in the forecast.
Any precipitation that does fall will be as rain and will be light.

Above normal lows tonight and Spring like temperatures are
expected Monday...though overnight temperature were decreased from
the previous forecast as todays temperature today were cooler than
anticipated.

Long term...Monday night through Sunday
issued at 256 PM CDT sun Mar 29 2015

As typical of the low-amplitude progressive flow...models
struggling with the system expected to cross the region Monday night. In
fact...there is probably more spread in the location of the
maximum precipitation on tdas runs compared with those 24 hours ago.
System still seems capable of producing a narrow band of near
advisory-criteria snow. The most likely location still seems to
be the far north near the Upper Michigan border...though confidence in
that is not high. Kept the likely probability of precipitation from the previous forecast for the
far north...and increased probability of precipitation a bit farther S as the north/S posn of the
precipitation now more in question. Will continue to have an inch or two of snow
across the far north in the grids...and mention in the severe weather potential statement.

Handling of the middle-week system is much more consistent...probably
because it/S a lot bigger. Timing is a bit slower now...so adjusted
grids accordingly. In fact...leading band of precipitation in isent lift
zone ahead of the cyclone may stay north of the forecast area entirely.
But a band of rain is still likely to sweep through the region Wednesday
night/early Thursday as cold front crosses the region. May eventually need
to add some thunder for at least the southern 2/3 of the forecast area. But
as of the now the precipitation band looks like it will cross the area at night
when instability will probably be at a minimum...so did not add
thunder to the grids yet.

The models have given up on or at least backed down substantially
on the idea of significant secondary development occurring once
the front pushes S of the area late in the week. But there is still
some upper level energy back to the SW...so that idea could
resurface at some point. Given the uncertainty...stuck with the
extended forecast initialization grids based on a broad blend of
guidance products.
&&

Aviation...for 18z taf issuance
issued at 1158 am CDT sun Mar 29 2015

Continued MVFR and IFR ceilings and precipitation are expected through
this afternoon and early evening as a frontal system swings
through the area. Any linger freezing precipitation should come to
end early this afternoon...with snow and freezing rain continuing
the longest in northern Wisconsin. After The Rounds of precipitation come
to an end...much better flying weather is expected as rain ends
and clouds scatter out then clear overnight. Gusty south winds
this afternoon will continue before veer west behind the front
early this evening...then diminish overnight. Monday should be
much nicer with VFR conditions and warmer temperatures.

&&

Grb watches/warnings/advisories...
none.
&&

$$

Synopsis.......skowronski
short term.....Allen
long term......skowronski
aviation.......Allen

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