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000
FXUS63 KGRB 230351
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1051 PM CDT Fri Sep 22 2017

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Saturday
Issued at 242 PM CDT Fri Sep 22 2017

Convection over northeast WI has been weakening and heading east
over the past couple hours, and is expected to exit the region
late this afternoon. A warm front was situated from around
AUW-OCQ-SUE, and was being enhanced by cloud cover and
convection/evaporational cooling over northern WI. Temperatures
ranged from the middle 60s far north to the upper 80s and lower
90s south.

The cold front should shift north of the region this evening,
leaving the forecast area in the capped warm sector tonight into
Saturday. Despite a very moist air mass, surface and boundary
layer winds should be strong enough to prevent any significant
fog from forming overnight. The exception may be advection fog
over Lake Michigan. A cold front will move into northwest WI
Saturday afternoon, but any precipitation chances should remain
to our northwest. Mild lows in the 65 to 70 range are anticipated
tonight, followed by unseasonably warm highs in the middle 80s to
lower 90s on Saturday.

.LONG TERM...Saturday Night Through Friday
Issued at 242 PM CDT Fri Sep 22 2017

The medium range models remain in good agreement with the pattern
change due to arrive in the Tue-Wed time frame next week. Will
continue to use a multi-model blend for this forecast.

Saturday night through Monday...Quiet, warm, and humid conditions
will continue on Saturday night through Sunday night, thanks to
strong sub-tropical ridging across the region. Sundays high temps
might be a degree or two cooler than Saturdays readings, but should
still range from the mid to upper 80s.  As a cold front moves
towards far western Wisconsin, the chance of storms returns to north-
central Wisconsin on Monday.  Shear parameters look too marginal for
a severe threat at this time. Eastern sections of the state should
remain dry, warm, and humid with highs in the mid 80s.

Rest of the forecast...The chance of storms will continue for north-
central Wisconsin on Monday night before spreading east on Tuesday
ahead of a cold front.  This front will mark the pattern change and
bring in more seasonable temps for Wednesday.  Shear parameters
improve on Tuesday along the front, so a severe threat looks higher
than on Monday.  Then mainly looking at dry and less humid weather
for Wednesday through the end of the week.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1032 PM CDT Fri Sep 22 2017

Mainly VFR conditions are expected through the TAF period,
however some light fog or haze may drop vsibilities into the IFR
category at times overnight. The main sites that appear
susceptible are RHI where it rained today as well as GRB and MTW
which have already showed signs of fog. Therefore will reduce
visibilities at these sites to IFR, however vsbys could fall
further. The other sites are more of a wild card as they did not
get any rain and have so far not shown signs of going down.
However given the high dew point airmass in place will reduce them
to MVFR for a time late tonight.

The other aviation concern for tonight into Saturday morning is
LLWS, which is expected to impact the RHI/AUW/CWA TAF sites from
through early morning, as southwest winds aloft increase to
around 40 kts. Will leave LLWS out of the GRB/ATW/MTW TAF sites
for now, as winds aloft are not quite as strong (25-35 kts) there.
&&

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

$$

SHORT TERM.....Kieckbusch
LONG TERM......MPC
AVIATION.......Kurimski