Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 231651
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1051 AM CST Thu Nov 23 2017

Updated aviation portion for 18Z TAF issuance

.SYNOPSIS...
Issued at 309 AM CST Thu Nov 23 2017

Quiet weather with warmer temperatures today. Windy and warm
Friday, then cooler (but still above normal) for the weekend.

The main westerlies across the CONUS will flatten the next couple
days, then reamplify some during the weekend. The pattern is
expected to become progressive next week, while maintaining low to
modest amplitude.

The westerly component to the upper flow will result in above
normal temperatures. A series of strong cyclones tracking across
Canada will be the primary factor controlling daily temperature
changes. Readings will vary from a couple degrees above normal on
some days to as much as 12-18F degrees above normal on others.
Moisture will be limited, so precipitation amounts will be light
despite the strong cyclones. Amounts are likely to end up below
normal for the period.
&&

.SHORT TERM...Today...Tonight...and Friday
Issued at 309 AM CST Thu Nov 23 2017

Some light snow and freezing rain produced scattered slippery
spots on area roads Wednesday evening, but the precipitation has
exited the area. Generally quiet weather is expected today and
tonight in it`s wake. Cloud trends today area a bit problematic.
Satellite indicated clouds back to the north and west were a
little more prevalent than the guidance suggested. Trended toward
more lingering clouds this morning, but still decreased clouds
later today. Cirrus will be streaming across from the northwest
today, but expect much of that to be thin. Raised maxes a bit
from the previous forecast, but not quite as far as a blend of the
top performing guidance products would have suggested--due to the
additional morning clouds.

Quiet weather is expected tonight. The Canadian RGL was an outlier
in generating precipitation across north-central Wisconsin this
evening and was ignored. The core of the strongest WAA and the
mid-level short-wave forcing the precipitation seemed too far
north to result in any precip in the forecast area.

A strong cyclone will track east across central Ontario on Friday.
Southwest winds will increase and become gusty as the warm sector
shifts through the forecast area. Models differed considerably on
the areal extent of precipitation by late in the day. The
precipitation is likely to be showery, and coverage of the showers
may also be an issue. Opted for mainly chance PoPs, with slight
chances in east-central Wisconsin, and likely PoPs over the far
northwest part of the area late in the day. Warmer air should
surge in from the Plains, so expect highs in the upper 40s to
middle 50s despite increasing clouds and the arrival of the
precipitation. Edged temps toward a blend of top performing
guidance products, which was warmer than the standard broad-based
forecast grid initialization blend.

.LONG TERM...Friday Night Through Wednesday
Issued at 309 AM CST Thu Nov 23 2017

Focus of the forecast remains on the impacts from a cold front
passing across the region on Friday night, followed by a potential
system for early next week.  Have a slight preference for the ecmwf
based on comparisons to the ensemble means.

Friday night through Saturday night...A strong cold front will be
exiting eastern WI on Friday evening, and could see a few showers
linger over the Fox Valley and lake shore through mid-evening.  Cold
advection will gradually ramp up late in the evening and overnight
behind the front, though wind trajectories never really veer enough
for a favorable lake effect component off Lake Superior.  Still
though, could see a few snow showers move across northern WI late
Friday night into Saturday.  Larger impacts probably revolve around
the gusty winds that are expected to develop as low level lapse
rates steep in the cold advection.  Some gusts to 30 mph appear
possible late Fri evening into Saturday morning. Though could see
some sun on Saturday morning over central and east-central WI,
northwest winds will be pushing a low stratus deck southeast across
the region, which should result in mostly cloudy skies for much of
the day.  High pressure will build in for Saturday night, but will
probably not see clearing until late in the night.

Rest of the forecast...High pressure will then move across the
region on Sunday.  With only cirrus overhead, should see some
filtered sunshine.  Warmer temperatures are expected on Monday as
winds shift to the southwest ahead of a sagging cold front.  Because
of the residual dry airmass in place across the region, precip is
not expected.  Plenty of uncertainty thereafter in regards to
location of frontal boundaries.  Models have backed off solutions
that bring a surface low through the region Tue and Wed.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1051 AM CST Thu Nov 23 2017

VFR conditions will prevail today into tonight as
southwest winds ahead of an approaching frontal system lifts a
dry air mass over the area. Increasing winds aloft will likely
develop LLWS conditions overnight followed with increasing
surface winds for Friday. MVFR cigs and showers ahead of a cold
front will work into the northwest portion of the state Friday
afternoon and continue tracking over the area Friday night.
&&

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

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Skowronski
LONG TERM......MPC
AVIATION.......TDH



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