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National Weather Service Green Bay WI
617 am CDT Tuesday Jul 29 2014

Updated aviation portion for 12z taf issuance

Short term...today...tonight...and Wednesday
issued at 359 am CDT Tuesday Jul 29 2014

Precipitation trends through the period...and the potential for a few
strong thunderstorms with hail this afternoon...will be the main forecast
concerns.

A short wave trough was exiting the southern part of the forecast area
early this morning...and another was approaching from Ontario.
Showers had ended across WI...though regional radar still showed
a few showers over the Minnesota arrowhead. Scattered-broken clouds covered the
region...and patchy fog had developed over NC WI.

The next short wave trough is expected to move through the forecast area
this afternoon (roughly from 18z-22z according to extrapolation)...
and should trigger scattered/numerous shra/tsra. Will carry high-end chance
or likely probability of precipitation over the entire County Warning Area. Modified forecast soundings (using
temperatures in the middle to upper 70s and dew points in the lower to
middle 50s) support SBCAPE of 1000-1500 j/kg and lifted indice's -3 to -5.
Wet bulb zero heights around 9k feet and cold air aloft (h5 temperatures -16
to -18) will be very favorable for hail. Storm Prediction Center has most of grb County Warning Area
in a 5% risk area for large hail...and this looks reasonable...so
will mention the potential for isolated severe thunderstorms this afternoon and
early evg in the hazardous weather outlook.

Another short wave trough will move through the region tonight...accompanied
by a weak Canadian cold front. Will have chance probability of precipitation during the evg...
and carry slight chances into the overnight hours before ending
late. Weak ridging over NC/far NE WI may allow patchy fog to
develop overnight. Lows temperatures should drop into the middle to upper
40s at the cool spots in the Northwoods...and lower to middle
50s elsewhere.

On Wednesday...another in a string of short wave troughs should pass by to
our northeast during the afternoon...with the lfq of a 70 knots jet
possibly impacting far NE WI. The air mass is not expected to be
as unstable as today...so afternoon convection should be isold/sct.
Mixing through 800-750 mb supports high temperatures in the lower to
middle 70s.

Long term...Wednesday night through Monday
issued at 359 am CDT Tuesday Jul 29 2014

Closed upper low over Ontario/Quebec Canada will meander across
the eastern portion of Canada into the weekend. Closed low will
eject eastward next Sunday into Monday. Persistent northwest flow
expected across the western lakes with periodic chances for
showers and storms through much of the period.

Timing of these features this far out difficult to pinpoint...but
best chances for showers and storms will be during the afternoon
and early evening hours Wednesday through Saturday. A lot of
uncertainty on how the Sunday and Monday will play out...thus did
not include in the hazardous weather outlook. Did adjust min
temperatures down a degree or two on a few nights. Only real
change was to add a few degrees to our typical warm spots/Sandy
soil regions. Later shifts may need to adjust Lakeshore region
down as water temperature at Sturgeon Bay this evening was only
50 degrees.
&&

Aviation...for 12z taf issuance
issued at 609 am CDT Tuesday Jul 29 2014

A couple upper disturbances will drop south out of Canada today
and tonight...leading to a chance of showers/thunderstorms over the
forecast area through at least this evening. The air mass will
become quite unstable this afternoon...so have added a tempo
group for thunderstorms at each of the taf sites. The stronger storms
will be capable of producing hail and gusty winds. Weak high
pressure is expected to build into northern WI late tonight...
and may lead to patchy fog development over parts of NC/far NE
WI...including the rhi taf site.
&&

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

$$

Short term.....Kieckbusch
long term......eckberg
aviation.......kieckbusch

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