Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 240910

Area Forecast Discussion
National Weather Service Green Bay WI
410 AM CDT Fri Mar 24 2017

Forecast discussion for routine morning forecast issuance

Issued at 408 AM CDT Fri Mar 24 2017

Occasional light freezing rain and drizzle across the north early
today, with a more persistent band of heavier rain from central
through northeast Wisconsin today and tonight.

Split flow now in place across North America, with the mean
trough position in the southern stream over the southwestern
United States. As a result, the southern stream systems that
manage to track far enough north to affect the area will be slow
moving and weakening by the time they arrive. One such system will
affect the area the next several days, with another probably
passing to our south early next week. A third system could affect
the area late next week.

The air mass across the area the next few days will be seasonable.
But widespread clouds, precipitation, and a stout northeast wind
will make it feel rather raw even though daytime highs will only
be a little below normal. Readings should warm to a little above
normal next week as the split flow keeps cold air locked up well
north of the area. Total precipitation for the period will be
primarily a result of the current system. Amounts will range from
well above normal across the southern part of the forecast area to
closer to normal across the north.

.SHORT TERM...Today...Tonight...and Saturday
Issued at 408 AM CDT Fri Mar 24 2017

Lots of forecast details to sort through this morning. Plan to
keep the advisory for the north through to expiration.
Temperatures were hovering near freezing. Precipitation has mainly
been sporadic and light, but temperartures will be favorable for
light icing to continue for several more hours.

The next issue is a substantial band of rain expected to develop
from central through northeast Wisconsin, and remain in place
today. Confidence in the band developing is high (it`s already
becoming apparent on radar), with the uncertainty concerning the
location of the southern and northern edges of the band. Whereever
it forms, it should sag south late today into tonight, then
probably come back north again Saturday as the main upper low
approaches from the southwest. At this point it appears the
primary precipitation area tonight will be far enough south for
mainly rain, though would not be surprised to see a mix along the
northern edge.

The final short-term concern is a frontal boundary that will sag
across the area this morning, then strengthen to our south today
and tonight as northeast winds increase. Although temperatures
will be just warm enough for the bulk of the precipitation to fall
as rain, the increasing northeast winds and temperatures in the
30s will likely create conditions perceived by most as very raw
and unpleasant--especially in the east where winds will be coming
off the lake and bay.

.LONG TERM...Saturday Night Through Thursday
Issued at 408 AM CDT Fri Mar 24 2017

00Z models were consistent in showing a surface low and 500 mb
low moving northeast from Missouri into Illinois Saturday night.
Thus, PoPs increase with even far north central Wisconsin in at
least chance PoPs by late Saturday night. Precipitation type is
once again an issue due to warm air aloft and surface temperatures
falling below freezing across a good portion of the area. Based
on QPF, an advisory would be necessary over the northern part of
the forecast area due to ice from freezing rain. Will let the day
shift take a look and see what he/she thinks after evaluating the
12Z version of the models.

More differences among the models show up on Sunday in their
treatment of both the mid level system and surface low. But they
all showed a large area of QPF covering most/all of Wisconsin.
Any freezing rain across the north should change to rain by
mid morning as temperatures warm. Precipitation chances decrease
on Sunday night as the surface and mid level systems depart, but
chance PoPs remain across the north in cyclonic flow. Chances for
freezing rain return and some sleet is also possible across
northern Wisconsin as temperatures drop overnight.

The 00Z GFS and ECMWF developed another surface low upstream from
the first, but its track is expected to be farther to the south.
Chances for rain continue on Monday ahead of an approaching mid
level trough. Generally dry weather is expected from about Monday
night through Wednesday as a surface ridge and a rather flat mid
level ridge pass across the state.

Model differences increase later in the week so have stuck with
the blended solution that had a chance for rain or snow Thursday
night, mainly over the north.

Highs should be in the 40s Sunday and Monday, but then warm into
the middle 40s to middle 50s range once we get rid of the rain
and some of the clouds. Lows should be in the middle 20s to middle
30s most nights.

.AVIATION...for 12Z TAF Issuance
Issued at 408 AM CDT Fri Mar 24 2017

Ceilings have held up pretty well thus far, but should settle into
the lower end MVFR and IFR range as precipitation becomes more
persistent and northeast flow strengthens.

Winter Weather Advisory until 9 AM CDT this morning for WIZ005-


SHORT TERM.....Skowronski
AVIATION.......Skowronski is the U.S. government's official web portal to all federal, state and local government web resources and services.