Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 221706
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1206 PM CDT Tue Aug 22 2017

Updated aviation portion for 18Z TAF issuance

.UPDATE...
Issued at 839 AM CDT Tue Aug 22 2017

Northwest winds are currently gusting up to 30 kts over the
northern and central Bay, so issued a small craft advisory. With
cold advection and model guidance showing 25 kts at 950mb
continuing into the evening, not sure how long these gusty winds
will last. Ended the advisory at 00z, thinking offshore winds may
slacken a bit with loss of heating, but with water temps near the
peak, its possible the small craft advisory will need to get
extended into tonight.
&&

.SHORT TERM...Today...Tonight...and Wednesday
Issued at 341 AM CDT Tue Aug 22 2017

A cold front was moving through eastern WI early this morning,
and a stronger secondary cold front was ushering in a much cooler
and less humid air mass over northwest and far north central WI.
Precipitation had just about ended, with only the tail end of a
line of showers and thunderstorms brushing far northeast WI.
Expect dry conditions to prevail by daybreak, with a clearing
trend occurring during the morning hours in the wake of the
secondary frontal passage. Northwest winds will become blustery,
with gusts to 20 to 25 mph at most locations. High temperatures
should range from the upper 60s northwest to the lower to middle
70s elsewhere.

Expect clear to partly cloudy skies across most of the forecast
area tonight. The exception will be over north central and parts
of far northeast, where cool north-northwest flow off Lake
Superior may lead to low clouds and patchy drizzle or light
showers. The light precipitation should taper off and low clouds
erode early Wednesday morning, followed by partly cloudy
conditions for the remainder of the day. Models suggest that a
weak surface trof may sag south through the area during the day,
but with dew points in the 40s and little or no instability, will
keep a dry forecast intact. Lows tonight should be in the middle
40s to middle 50s, with highs on Wednesday in the 60s and lower
70s.

.LONG TERM...Wednesday Night Through Monday
Issued at 341 AM CDT Tue Aug 22 2017

Cool northwest flow aloft regime will dominate the region for the
remainder of the work week. Progs continue to track a short wave
trough with 80 knot upper jetlet over the southwest half of the
state Wednesday night into Thursday. Consensus of the latest
progs is a further southwest track and drier forecast for central
Wisconsin. This system will also be working over a relatively dry
air mass. Temperatures will be cooler than normal for the
remainder of the work week, with overnight lows across the north
possibly dipping into the upper 30s in the climatological cool
spots. Clear skies, light winds and longer nights will likely lead
to patchy fog as well.

Precipitation chances begin to increase from the west for the
weekend and early next week as the return flow works back north
across the Plains. The surface high pressure ridge over the Great
Lakes region will likely keep the precipitation chances minimal
at this time. Instability is also minimal at this time for any
introduction of thunder.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1052 AM CDT Tue Aug 22 2017

Cloud bases continue to rise at midday, and should settle in the
4000-5000 ft range this afternoon. As a weak disturbance moves
southeast, short range guidance indicates that a few showers could
move into north-central WI this evening, though confidence is not
high enough to include in the RHI taf. Otherwise, cool north-
northwest flow off Lake Superior will bring some low clouds and
patchy light showers or drizzle to north central WI late tonight,
but conditions should remain VFR farther south and east. Gusty
northwest winds will diminish after sunset.

&&

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

$$

UPDATE.........MPC
SHORT TERM.....Kieckbusch
LONG TERM......TDH
AVIATION.......MPC


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