Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 220818
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
318 AM CDT Fri Sep 22 2017

Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Saturday
Issued at 318 AM CDT Fri Sep 22 2017

Primary forecast issue today into Saturday centers on fog
potential along the lakeshore and bay, convection trends over
the northwest portion of the state, and max min temperatures.

As of 300 am, fog along the lakeshore has diminished with the fog
imagery indicating pockets of fog between Two Rivers and Kewaunee
at this time. Web cams have shown improvement early this morning
but will let the lakeshore fog advisory run for another few hours
to see if redevelopment occurs. Otherwise anticipate patchy fog
along the lake will continue into the weekend with surface
dewpoints well into the 60s.

For convection trends this morning, area radars show clusters of
mainly elevated thunderstorms moving northeastward over
Minnesota. The storms will be sliding near the DLH vicinity
through 5 am. Radar does show some weaker turns showing up over
northwest Wisconsin at 3 am, but still west and northwest of
Oneida and Vilas Counties. A few meso models do track convection
originating over northeast South Dakota, over north central
Wisconsin during the morning hours. Height 850 to 300 thickness
fields indicate a southwest to northeast flow before shifting west
to east over northern Wisconsin. Surface warm front appears to
have lifted north of the area but 925 mb progs indicate a frontal
boundary over the north this morning may be the main focus of
convection across the area. Mid level clouds increasing across
this area may also be pointing out this boundary location.
Anticipate convection to continue to move mainly northeastward and
west of the area, but will continue to keep a small chance of
elevated convection over at least northern Wisconsin due to the
increasing elevated capes through today.

For tonight into Saturday, will continue the dry forecast as the
upper ridge and cap dominates. Its possible a storm may pass near
north central Wisconsin, but the potential is too low at this
time to add to the forecast.

With the warm front lifting north of the area tonight into
Saturday, south winds will continue to pump in a very warm and
humid air mass into the area. Temperatures will continue to run
nearly 20 degrees above normal.

.LONG TERM...Saturday Night Through Thursday
Issued at 318 AM CDT Fri Sep 22 2017

500mb ridge across the eastern United States will bring record or
near record warmth across our area Saturday/Sunday with highs well
into the 80s. A few readings in the lower 90s are possible on
Saturday. Showers and thunderstorms to the north and west of the
state could spill into far north-central Wisconsin at times this
weekend.

A major shift in the 500mb pattern will take place during the first
half of next week. A western ridge will build with a downstream
trough across the eastern United States. Temperatures will gradually
trend towards normal by late next week. Meanwhile, a cold front
will slowly push east towards the area on Monday, and then across
the area on Tuesday. Do have chances of showers and thunderstorms
on Monday, but confidence is low if the rain will materialize on
this day. Tuesday is looking a little bit more interesting with
stronger wind aloft (greater than 50kts) with the area being in
the right entrance region of a 100+ knot jet. If these wind fields
materialize, there may some potential for severe weather across
the area. Still pretty far out to mention severe wording, but it
is something to watch over the next few days. Continued the small
chances of showers on Wednesday with dry conditions on Thursday as
high pressure builds into the region. Temperatures on Thursday
will be close to normal.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1059 PM CDT Thu Sep 21 2017

Plenty of issues just in the short term make this a low confidence
forecast. Rain that most of the synoptic scale models had reaching
the area by 06Z at the latest, has not yet developed. HRRR had a
few specs in central/north central Wisconsin on the simulated
reflectivity product, but just for a couple of hours and then
nothing moves in until around 14Z when showers and storms reach
Vilas County. In the mean time mostly clear skies prevailed, but
dew points were well into the 60s and it will not take much for
temperatures to drop enough for fog development. IFR/LIFR
conditions in dense fog prevailed close to Lake Michigan and the
fog could advect farther inland overnight.

Will go with mostly MVFR and/or IFR conditions in fog at most
locations overnight. Some low ceilings may also develop. Plan to
bring showers and storms in during the morning and continue them
east into the afternoon.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM CDT this morning for WIZ022-040-
050.
&&

$$

SHORT TERM.....TDH
LONG TERM......Eckberg
AVIATION.......MG



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