Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 161119
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
519 AM CST Thu Nov 16 2017

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Friday
Issued at 306 AM CST Thu Nov 16 2017

Gusty winds continue behind a low pressure system exiting the
western Great Lakes this morning. Some light snow showers were
noted across far north-central Wisconsin with lake effect snow
from the Lake Superior snowbelt. Winds will die down this morning
as lake effect snow showers come to an end as high pressure builds
in from the west. Models continue to indicate that skies will
clear out today as the ridge tracks through the area, however
upstream satellite observations bring this into doubt. Even if the
area clears out later today, the next system approaching from the
west will bring clouds back to the region later this afternoon and
into the early evening hours. Highs today will generally be in the
30s.

A low pressure system will track through later tonight into
Friday, bringing a mixed bag of precipitation types to northeast
Wisconsin as it tracks through the region. Lows tonight should
occur during the evening hours, then rise during the rest of the
night as winds turn southerly. Mid level dry air and a warm layer
will mean sleet and freezing drizzle will be a possibility, as
well as snow as the column is saturated at times. The weak lift
and dry layer should keep the liquid portion of the precipitation
as mainly drizzle, until deeper moisture and better dynamics
transition this to rain Friday afternoon. The mixed precipitation
could make the morning commute interesting on Friday, especially
across central and north-central Wisconsin. Snowfall amounts are
expected to be fairly light given the other precipitation types
expected with icing expected to be fairly light given the weak
dynamics during the morning hours. The main question will be how
cold the roads are and how much liquid precipitation falls. Right
now it appears to be fairly minimal, however if that changes the
impact could worsen depending on future forecasts.

.LONG TERM...Friday Night Through Wednesday
Issued at 306 AM CST Thu Nov 16 2017

Precipitation chances/types Friday night and Saturday, wind speeds
and gusts on Saturday into Saturday night, and the potential for
lake effect snow showers lingering Saturday night into Sunday are
the main concerns with this package.

For Friday night, the precipitation should start out as light rain
or drizzle. The colder air is slower to work into the area
compared to several days ago, so any change over to snow well
north and west of the Fox Valley would not occur until well
after midnight Friday night. Latest model guidance would not
suggest a mix at Wausau until almost sunrise on Saturday morning.
Roads could become slick again late Friday night into Saturday
morning across north-central Wisconsin. The colder air will
gradually work across the area on Saturday for the opening of the
deer hunting season. Latest bufkit soundings indicated most of
the precipitation on Saturday would be in the form of rain across
the Fox Valley/lakeshore region until the afternoon where a mix
is possible before the precipitation ends. It will be mainly snow
across the north, could be a little rain early Saturday morning
if air temperatures are a few degrees above freezing at a few
spots. Across central Wisconsin, a mix of rain/snow is expected.
Probably the bigger issue is expected wind speeds/gusts. 00z
bufkit soundings tonight would suggest gusts of 35 to 40 knots are
possible due to deep mixing due to steep low level lapse rates.
Have increased wind speeds/gusts, but not as high as the bufkit
soundings suggest. Want to see one more model run to ensure the
strength of the winds. A wind advisory may be needed for Door
county, and possibly some portions of northeast Wisconsin.
Temperatures should fall slowly through the late morning and
afternoon hours on Saturday.

Lake effect snow showers will linger across the far north
Saturday night into Sunday with northerly flow off Lake Superior.
There is small chances of precipitation across the far north
early next week, but confidence is low. Temperatures will
be on a roller coaster ride, with middle 30s to lower 40s
Saturday, upper 20s to middle 30s Sunday warming back into
the upper 30s to middle 40s Monday before plunging again
on Tuesday.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 519 AM CST Thu Nov 16 2017

Gusty west to northwest winds will continue to subside this
morning. MVFR cigs will gradually improve to VFR today from west
to east as high pressure moves through the region. Low pressure
will bring MVFR cigs back to the area tonight as a wintry mix
falls over portions of central and north-central Wisconsin.
&&

.MARINE...
Issued at 306 AM CST Thu Nov 16 2017

Northwest Gales are expected to continue along the Door peninsula
this morning, before easing throughout the daytime hours. Gales
look to occur for a few more hours than previously expected,
therefore will extend the Gale Warning through 9 am. After the
Gales, small craft conditions are expected through mid-day, with
all headlines expected to end by the afternoon hours.

Another low pressure system could bring additional chances for
gale force winds, first from the south on Friday ahead of the
system, then from the northwest behind the system on Saturday and
Saturday evening. Given the fairly high confidence on the
southerly Gales across most zones on Friday will issue a Gale
Watch for all areas save for the southern Bay of Green Bay during
the daytime hours with this issuance.
&&

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

$$

SHORT TERM.....Kurimski
LONG TERM......Eckberg
AVIATION.......Kurimski
MARINE.........Kurimski


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