Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 241731

Area Forecast Discussion
National Weather Service Green Bay WI
1231 PM CDT FRI JUN 24 2016

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Saturday
Issued at 328 AM CDT Fri Jun 24 2016

With the exception of some patchy morning fog early this
morning...mainly mostly sunny skies expected today under a high
pressure regime. A mix of progs suggests some diurnal cu
development today. As the high pressure region drifts
east...winds turn more south this afternoon with a northwest flow
aloft. Best return flow and returned instability will lie to the
west as a short wave trough drops into the northern plains today
into tonight.

LLJ will lifting deeper moisture and instability into the
northern plains tonight will increase convection over minnesota.
Some of this convection may spill into northwest Wisconsin late
tonight including north central Wisconsin toward morning. This
debris convection from the northern plains may reduce instability
at the onset saturday as the llj begins to lean into western
Wisconsin. Will continue with the trend with ramping up pops on
Saturday as pwats and instability will be on the increase ahead
of a cold front and dry slot over the northern plains.

.LONG TERM...Saturday Night Through Thursday
Issued at 328 AM CDT Fri Jun 24 2016

Thunderstorms Saturday night are the main concern during this
part of the forecast.

Have categorical pops for the entire area Saturday night as a
cold front moves in from the west. By that time dew points are
expected to be in the 60s with CAPEs mostly in the 1000-2000 J/kg
range and LLJ around 35 knots. SPC day 2 outlook had at least a
marginal risk of severe storms across the entire forecast area
with a slight risk in parts of central and north central
Wisconsin. It appears that Minnesota and western Wisconsin are
the more likely locations for any severe storms since instability
is forecast to decrease quickly on Saturday evening. PW values are
still forecast to be in the neighborhood of 2 inches, so heavy
rainfall is a pretty good bet. Some storms may linger in far
eastern Wisconsin on Sunday morning but they should be out of the
area fairly early in the day.

There is a slight chance for showers on Sunday night and Monday in
north central Wisconsin with a mid level short wave and surface
cyclonic flow. Other than that, surface high pressure should help
to keep things dry for much of the upcoming week. There is a chance
for thunderstorms in northern Wisconsin on Thursday with an
approaching cold front and mid level short wave, but models were
showing some timing differences with this so confidence level is
low regarding pops on Thursday.

High temperatures should be above normal on Sunday, but they will be
much cooler than normal behind the front on Monday and Tuesday,
before it warms up again Wednesday and Thursday in return flow.

.AVIATION...for 18Z TAF Issuance
Issued at 1230 PM CDT Fri Jun 24 2016

High pressure over the Great Lakes this afternoon is forecast to
slowly shift east toward the Eastern Great Lakes tonight. VFR
conditions are expected through tonight with Saturday morning.
Current cu field at 5-6KT feet will dissipate this evening, with
mid/high clouds arriving overnight as showers/thunderstorms
develop to our west as WAA increases in advance of a warm front.
A few of these showers/storms may approach the RHI TAF site toward
daybreak/Saturday morning, otherwise dry conditions are expected
until later Saturday afternoon as a cold front pushes across MN.



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