Area Forecast Discussion
Issued by NWS Green Bay, WI

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311
FXUS63 KGRB 220359 CCA
AFDGRB

Area Forecast Discussion...CORRECTED
National Weather Service Green Bay WI
1059 PM CDT Mon Oct 21 2019

Updated aviation portion for 06Z TAF issuance
and new information added to update section

.UPDATE...
Issued at 959 PM CDT Mon Oct 21 2019

Have allowed the Lakeshore Flood Advisory to expire. Winds have
turned south to southwest and diminished, so strong onshore flow
has ended. As a result, water levels have already dropped about a
foot, and continue to fall. Calls to local sheriff departments
indicated that flooding conditions had improved in most areas,
though at least minor flooding was likely still occurring in
localized areas near the bay. A lack of recent on site reports
made it difficult to fully assess the situation, but meteorological
conditions suggested continued improvement should occur.

UPDATE
Issued at 700 PM CDT Mon Oct 21 2019

The wind advisory for Door county will be allowed to expire, as
winds have dropped well below advisory criteria.

Isolated thunderstorms will continue over far northern WI, where
MUCAPE was around 400 j/kg within the nose of the dry slot. Will
update the forecast to extend a slight chance of storms for a
couple more hours.

An area of locally dense marine fog was lifting up the Lake
Michigan shoreline. Models show this moving out of the area
by around 02z or shortly thereafter, so will just handle with
Marine Weather Statements on the lake and Special Weather
Statements for the shoreline areas.

Will be calling around to determine whether or not coastal
flooding is still occurring this evening. Water levels have come
down a bit since they peaked earlier in the day, and winds are
turning southerly, so conditions are expected to gradually
improve. The current Lakeshore Flood Advisory is in effect until
10 pm.
&&

.SHORT TERM...Tonight and Tuesday
Issued at 252 PM CDT Mon Oct 21 2019

The latest RAP analysis and satellite/radar imagery show a strong
area of low pressure along the western Wisconsin and Minnesota
border early this afternoon. Moderate to briefly heavy rain
continues to move northeast across much of Wisconsin. The
strongest showers have been bringing down isolated strong gusty
winds in the 40 to 50 mph range mainly over the Fox Valley and
Lakeshore. Gale force gusts are also occurring over the Bay and
Lakeshore, with reports of high water occurring along the
shoreline near Suamico. Given the current winds, no change to the
ongoing wind advisory or lakeshore flooding headlines. Not out of
the question that an isolated rumble of thunder could occur as
well south of Hwy 29. Meanwhile, the dry slot is pushing into
southwest Wisconsin with partial clearing ongoing. Additional
showers and a few thunderstorms are also occurring within the
comma head of the cyclone over western Iowa and far eastern
Nebraska. As this cyclone moves across the region over the next 24
hours, forecast concerns include precip trends and strong wind
potential.

Tonight...Low pressure will lift northeast across far northwest
Wisconsin and western Lake Superior. Showers will continue to
rapidly lift northeast ahead of the dry slot and clear far
northern Wisconsin and Door County early this evening. The
strongest winds look to occur just ahead of the dry slot within
the heaviest showers, so winds should subside somewhat as the
showers exit and winds shift to the southwest. A lull in the
precip should then persist until early overnight. Then deeper
moisture will return beneath the comma head overnight and bring
widespread light rain and drizzle to the region. As cold advection
moves in, winds may increase again towards day break, mainly over
eastern WI. Low temps mainly ranging through the 40s.

Tuesday...The upper cyclone will continue to lift north across the
Upper Peninsula and Lake Superior. Progged soundings are quite
moisture-laden through the day, with saturation extending up
through 700 mb. This should result in periods of light rain and
drizzle. Weak cold advection will continue which should serve to
steepen low level lapse rates up to 900 or 875 mb, where winds are
projected to reach into the 35 to 40 kt range. As a result, could
see wind gusts of 35 to 40 mph, mainly over central and northeast
WI where the pressure gradient will be tighter. Blustery highs
ranging from the mid 40s to near 50.

.LONG TERM...Tuesday Night Through Monday
Issued at 252 PM CDT Mon Oct 21 2019

Showers will diminishing Tuesday night as the upper
low moves off towards Hudson`s Bay. A few snowflakes could mix in
with the rain Tuesday night but it`s not cold enough aloft for
anything more than that.

A Clipper system could bring some light rain or snow to east
central Wisconsin Wednesday afternoon and evening, but the bulk of
it should stay to our south.

Otherwise generally dry and cooler than normal weather expected
for the middle and end of the week with northwest upper flow and
surface high pressure passing by to our south.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 959 PM CDT Mon Oct 21 2019

Wrap-around showers with a low pressure system will overspread
the region from west to east overnight, along with lowering
ceilings and vsbys (MVFR/IFR). Showers and IFR/MVFR flight
conditions will continue through most of the day on Tuesday,
though some improvement should be noted in the late afternoon and
evening as showers gradually taper off.

Winds will diminish a little tonight before turning west and
increasing again on Tuesday. Westerly gusts will reach 30 to 35
knots in central and east central WI during the afternoon and
early evening. LLWS should gradually taper off overnight.
&&

.MARINE...
Issued at 252 PM CDT Mon Oct 21 2019

A strong low pressure system will passing through the area tonight
and Tuesday. Ahead of the low, wind gusts will peak this afternoon
in the 35 to 40 kt range, before subsiding somewhat this evening.

After winds veer to the southwest, winds are expected to increase
again late tonight into Tuesday. Gusts in the 35 to 40 kt range
appear likely from late tonight into Tuesday evening.

Wind gusts will be approaching gale force through Tuesday night.
As a result, have extended the gale warning for the Bay until 00z
Wednesday.
&&

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

$$

UPDATE.........Kieckbusch
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......Kieckbusch
MARINE.........MPC



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