Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 111006
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
406 AM CST Sat Nov 11 2017

Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Sunday
Issued at 405 AM CST Sat Nov 11 2017

Strong warm air advection and the right entrance region of an
upper jet combined to produce an inch or two of snow across
central and northcentral Wisconsin overnight. The snow was having
a hard time making it into east central Wisconsin at 10z, as dry
air was being advected in from the south in the Fox Valley and
lakeshore counties. The snow should eventually make it into those
areas and produce a dusting to inch of snow.

The snow could continue into the evening hours over the lakeshore
counties as some of the models suggest that a weak coupled jet
will keep vertical motion going in that area. There could be some
drizzle or freezing drizzle as mid level moisture and ice crystals
depart. Nearly steady temperatures expected tonight.

Sunday should be mostly cloudy and a bit milder with temperatures
in the 30s.

.LONG TERM...Sunday Night Through Friday
Issued at 405 AM CST Sat Nov 11 2017

The mean flow appears to remain fairly constant over the extended
period with an upper ridge over the eastern Pacific, an upper
trough over the West Coast and a progressive near zonal flow
across the rest of the CONUS. Models are in good agreement
through the middle of next week, especially with the handling of a
system expected to hit the western Great Lakes Tuesday afternoon
through Wednesday morning. Problems arise for late next week as
the models have some serious disagreement on the timing and
strength of the next system. Such a vast array of possibilities
exist that it make take a few days for the models to come into a
reasonable consensus. Temperatures are still expected to moderate
to or go slightly above normal next week.

A surface ridge axis is forecast to move into western WI later
Sunday night, bringing generally partly cloudy skies and a light
west-northwest wind to northeast WI. Temperatures appear to be
seasonal with readings dipping into the upper teens to lower 20s
north, lower to middle 20s central/far northeast and middle to
upper 20s east-central WI. This surface ridge slowly moves across
WI on Monday and is expected to reside over eastern WI by 00z
Tuesday. Look for a mix of sun and clouds through the day and as
weak WAA develops, anticipate max temperatures to be in the middle
30s north-central WI, upper 30s to around 40 degrees south.

As the high pressure finally exits the area Monday night, a return
flow sets up over the Upper Midwest/western Great Lakes. WAA will
continue into WI, but with a dry air mass in place, only
anticipate a general increase in cloud cover through the night.
The combination of clouds and south winds will provide for milder
conditions with min temperatures only in the middle to upper 20s
north, upper 20s to lower 30s south. It still appears that the
atmosphere will saturate enough by Tuesday to bring a chance of
light rain to the forecast area as the WAA pattern persists and
deeper low-level moisture arrives. Temperatures would continue to
slowly moderate with readings reaching the lower 40s north, middle
40s south.

Models are in good agreement in sending a cold front/trailing
shortwave trough into the western Great Lakes Tuesday night.
Temperatures should be warm enough to allow most of the
precipitation to fall as all rain, although snow is expected to
mix with the rain over the north after midnight. The
precipitation chances will continue into Wednesday morning until
the shortwave trough shifts east. There may be some mixed
rain/snow toward the back end of the precipitation shield, but
with the heavier QPF already to our east by Wednesday morning,
there should be no weather issues of consequence. The rest of
Wednesday will see clouds on the decrease, especially during the
afternoon hours. Even with the passage of the cold front, max
temperatures will still be able to reach the lower to middle 40s
north, middle to upper 40s south.

A weak area of high pressure is forecast to move across WI
Wednesday night, followed by increasing clouds on Thursday as the
next surge of WAA heads in our direction. A cooler start to the
day, plus the expected thickening clouds, will keep temperatures a
bit cooler compared to Wednesday. Look for max temperatures on
Thursday to be in the upper 30s north-central, lower 40s
elsewhere.

Forecast confidence takes a significant dip toward the end of the
work week as the models have serious timing issues with a
potentially strong system taking aim at the Great Lakes. Just too
may scenarios at this point to make an educated forecast on both
precipitation timing or precipitation type. For now, will simply
increase pops Thursday night into Friday and see how the models
shake out in the coming days.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1038 PM CST Fri Nov 10 2017

Snow will move across the northern half of Wisconsin overnight
into Saturday morning. Still some uncertainty in the southern
extend of the snow, but KATW/KGRB/KMTW should see at least a
few hours of light snow towards 12z. It appears the models
are ending the precipitation earlier than anticipated from
this morning. The only exception is the Canadian model which
brings more snow into the area late Saturday afternoon and
Saturday evening. Have discounted the Canadian model for now
for the 06z tafs. Midnight shift will get to take a look at
the new European model to make any necessary adjustments.
The snow may end as freezing drizzle as well.

The MVFR CIGS have developed across central and north-central
Wisconsin and will continue overnight. MVFR CIGS are expected
to develop across northeast and east-central Wisconsin on
Saturday, especially during the afternoon hours.
&&

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

$$

SHORT TERM.....RDM
LONG TERM......Kallas
AVIATION.......Eckberg



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