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Area forecast discussion
National Weather Service Green Bay WI
634 PM CDT Tue Oct 22 2019

Updated aviation portion for 00z taf issuance

Short term...tonight and Wednesday
issued at 254 PM CDT Tue Oct 22 2019

The latest rap analysis and satellite/radar imagery show a strong
area of low pressure lifting north of Lake Superior early this
afternoon. Deep moisture within cyclonic flow continues to wrap
around the low, and provide periods of showers and drizzle. Winds
have been gusting up to about 35 mph at times, highest over
northeast WI and might increase slightly around mid-afternoon, but
should remain below Wind Advisory criteria of 45 mph. Looking
upstream, widespread low overcast extends west into Minnesota and
south into east-central Illinois. Forecast concerns revolve around
strong wind potential and light precip trends.

Tonight...low pressure will continue to lift northeast over
northern Ontario. Deep cyclonic flow will continue, however, with
thermal troughing and a strengthening inversion supporting low
overcast to persist through much of the night. It's possible
central WI and the downsloping areas of northeast WI could see
some holes in the clouds develop late. Forecast soundings remain
support of areas of light rain and drizzle persisting into the
evening as saturation folds over the top of the inversion. But as
the low moves away, should see light precip chances diminish and
lift north through the night. After peaking late this afternoon,
should see winds gradually diminish through the night as well.
Temps wont fall much due to cloud cover and the breezy conditions,
with lows falling into the middle 30s to near 40 by the lake.

Wednesday...though low pressure will continue to move farther away
from the region, the low overcast will be slow to lift north, and
may hang around northern WI through the afternoon. Meanwhile, any
clearing that occurs over central and east-central WI looks to be
short-lived as a shortwave trough will quickly move across the
northern Mississippi Valley and into the western Great Lakes in
the afternoon. It will bring a low chance of light rain into
parts of central and east-central WI, mainly in the late afternoon
hours. Highs ranging from the low 40s in the north to near 50 in
the east.

Long term...Wednesday night through Tuesday
issued at 254 PM CDT Tue Oct 22 2019

Cool and dry weather is expected Wednesday through
Saturday as northwest upper flow prevails across the Great Lakes.
Temperatures should range from 5 to 10 degrees below normal.

The medium range models have differences as far as Saturday night
and Sunday go. The GFS moves an upper trough across the lower Ohio
Valley keeping Wisconsin dry, while the European model (ecmwf) and Gem have a
negatively tilted upper system lifting northeast across Illinois
which would bring a chilly rain to the area. The jet energy for
that system is still off the Pacific coast so we do not have a lot
of confidence in any of the model forecasts yet.

Aviation...for 00z taf issuance
issued at 629 PM CDT Tue Oct 22 2019

The strong low pressure system will continue to lift northeast
away from the region through the taf period. However, deep and
moist cyclonic flow will continue, resulting periods of light rain
and drizzle through this evening. Cigs and vsbys will mainly be
MVFR, but may briefly fall to IFR in north central WI, especially
when it is raining. MVFR conditions should prevail on Wednesday,
except in eastern WI, where improvement to VFR is anticipated
during the late morning and afternoon.

issued at 254 PM CDT Tue Oct 22 2019

After a lull this morning, southwest winds are
projected to increase again but remain under gale force late this
afternoon into this evening. If winds proceed as planned, think
the Gale Warning will likely get downgraded to a Small Craft
Advisory on the Bay and possibly on the lake too. Winds and waves
that are hazardous to small craft will then likely continue until
Wednesday afternoon.

Grb watches/warnings/advisories...


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