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430
FXUS63 KGRB 131004
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
404 AM CST Wed Nov 13 2019

Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Thursday
Issued at 404 AM CST Wed Nov 13 2019

Challenging forecast this morning as there are
subtle but important model differences that are resulting in
varying amounts and placements of the snow we are expecting
today. In addition, the atmosphere is initially dry, so some of
the lift being produced by upper jet action and low level warm
advection is being used to lift and saturate the air.

The models all have some sort of a coupled upper jet that moves
across the area today. One jet is departing the Western Great
Lakes while one is approaching from the Central Plains. The
majority of the 00z and 06z models have the best forcing across
far northeast Wisconsin while the 00z ECMWF is further south
across the east central part of the state.

Think that an area of light snow will move across the entire area
this morning, the steadiest snow north of highway 29. Then expect
the majority of snow in the afternoon to be across east central
and far northeast Wisconsin. The surprising thing about the snow
is that it is unusually cold for this time of the year, and
precipitation type is not an issue. The snow should end from west
to east this evening with clearing late tonight and Thursday.
Temperatures will remain well below normal.

.LONG TERM...Thursday Night Through Tuesday
Issued at 404 AM CST Wed Nov 13 2019

Quiet conditions will cover the early extended as high pressure
dominates the region. Once this departs, return flow will bring
rising temperatures closer to normal by the start of next week,
but also a few period of unsettled weather in the latter part of
the weekend and next week.

Thursday, upper level ridging will continue to build over the
region as high pressure conditions dominate. Continued the dry
forecast for the time period through Saturday afternoon. Moisture
and forcing will be limited during this time period, despite a
weak cold front moving into northern Wisconsin. As upper level
flow becomes less amplified through this period, our access to the
abnormally cold air will begin to get cut off, which will lead to
some improvement in the overall temperatures. Expect the region
to get to within ten degrees of normal by Saturday.

Saturday afternoon and evening, the next shortwave will enter the
region as the surface high pressure system departs to our east.
Models still vary some on the arrival time for active weather with
this feature but the best chance will be Saturday overnight into
Sunday. Precipitation is expected to be mainly snow overnight, but
could change over to rain briefly on Sunday as warmer air pushes
into the region from the south. This return flow on Sunday will
also help continue the trend of increasing our daytime high
temperatures to the middle to upper 30s by the start of the work
week.

For the rest of the extended period, the upper level trough will
continue to build over the region for the beginning of the work
week. Several shortwaves riding through this trough will bring
periods of unsettled weather for the region, with brief bouts of
snow showers, and mixed precipitation. Flow at the surface will
remain mainly south to southwesterly during this time, bringing
high temperatures close to normal by the middle of next week.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 854 PM CST Tue Nov 12 2019

Aviation weather conditions are expected to gradually deteriorate
during the next 12-18 hours as light snow develops across the
region. Snow, and associated lowering ceilings and visibility is
expected to develop Wednesday-- initially across the north during
the morning, and then across central and east- central Wiscnsin
during the afternoon. Anticipate a period of IFR conditions
tomorrow afternoon into the evening as the snow affects the
region. Increasing winds aloft overnight will result in some
LLWS-- mainly across the western portion of the area.
&&

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

$$

SHORT TERM.....RDM
LONG TERM......Uhlmann
AVIATION.......Skowronski