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Area forecast discussion 
National Weather Service Green Bay WI
1237 PM CDT Sat Aug 30 2014

Updated aviation portion for 18z taf issuance

Short term...today...tonight...and Sunday
issued at 253 am CDT Sat Aug 30 2014

Precipitation trends today through early this evening the primary
focus. A good portion of the forecast area picked up soaking
rain overnight...with the more widespread rain approaching east
central Wisconsin this morning. Widespread showers with isolated
storms will continue this morning over the forecast area as the
middle level short wave trough slides over. At 08z the center of a
surface low was located near LaCrosse with a warm front extending
into east central Wisconsin. Area radars show showers extending
west into eastern Minnesota.

A vorticity was located in the base of this deep trough and will rotate
into Wisconsin this morning to continue the threat of showers and
isolated storms. Will not be to quick to end the convection today
as models in good agreement with dropping a northern stream short
wave into the initial system to maintain convection this afternoon
and likely into the evening over far northeast Wisconsin until the
phasing trough system departs east.

Mean relative humidity supports clouds to linger tonight...as a weak ridge slides
over. With the recent rain...and light winds and possibility of
partial clearing skies tonight...will keep the fog mention. The
fog could become more of an issue if clearing becomes widespread
in the wake of the trough. Upstream observations so far reveal a
MVFR to IFR stratus clouds behind this system.

Next system approaching from the plains will lift a warm front
back north over the state. Some models are producing some minor
convection. Will leave the forecast dry for now...but later shifts
may need to intro a small pop with the frontal passage if this trend is
consistent.

Long term...Sunday night through Friday
issued at 253 am CDT Sat Aug 30 2014

Precipitation trends are the main concern during this part of the
forecast. Upper level flow across the Great Lakes region should
generally be zonal during the upcoming week.

Timing among models is similar with a middle level short wave moving
across Wisconsin Sunday night and Monday as a surface low drags a
cold front through the state. Upper jet dynamics are expected to
enhance lift on Monday so this Labor Day looks like it will be a
wet one. A weak short wave passing through the region brings a
chance for showers on Tuesday. Surface high pressure and a weak
upper level ridge should keep Tuesday night and Wednesday
generally dry. Chances for thunderstorms return on Wednesday night
and continue through Friday as a middle level trough and surface low
and cold front approach and make their way across Wisconsin.
Models varied in their treatment of the surface boundary...adding
more uncertainty to this part of the forecast.

Temperatures should be near or above normal for most of the long term.
&&

Aviation...for 18z taf issuance
issued at 1236 PM CDT Sat Aug 30 2014

Plenty of IFR/MVFR ceilings rotating around an upper trough over the western
Great Lakes region this afternoon. Radar continues to show numerous
bands of showers moving through NE WI with the back edge slowly working
into western WI. Expect this precipitation to gradually shift east and come to
an end by early evening over eastern WI. Weak surface and upper ridging to
occur later tonight which may allow skies to at least become partly
cloudy for a time. Problem is fog development as much of the
region has had heavy rainfall over the past 24 to 36 hours. Any
improvement in ceilings will be replaced by reduced visibilities into the LIFR
to IFR range late tonight as the fog overspreads the area. This fog
is expected to gradually dissipate by late Sunday morning allowing
for a return to VFR conditions for the rest of the day.
&&

Hydrology...
issued at 253 am CDT Sat Aug 30 2014

Much of central and north central Wisconsin picked up
a soaking rain overnight and still ongoing as of early Saturday
morning. Radar estimates suggest an inch to 1.50 inches but
locally higher amounts over eastern Portage and western Waupaca
counties. Showers and storms with higher rainfall rates just
working over east central Wisconsin early this morning but moving
at a good clip. Steady wrap around showers will continue this
morning as the surface low and upper trough slide over. A warm
front extends from the low at arx at 08z to near osh to mtw and
could be a focus for more convection and heavy rain this morning.
&&

Grb watches/warnings/advisories...
none.
&&

$$

Short term.....Tdh
long term......mg
aviation.......AK
hydrology......tdh

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