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Area forecast discussion 
National Weather Service Green Bay WI
1248 PM CDT Wednesday Jul 23 2014

Updated aviation portion for 18z taf issuance

Short Thursday
issued at 215 am CDT Wednesday Jul 23 2014

A cooler drier but more comfortable air mass will dominate the
region today into Thursday as a surface high pressure settles into
the western Great Lakes region. Line of convection with a cold
front was dropping southward over the Ohio Valley and Illinois
early this morning.

Some patchy fog was noted across north central Wisconsin early
this morning and patchy fog will likely occur again tonight under
light winds and clear skies.

A few models are producing some light precipitation amounts this afternoon
across the region...European model (ecmwf) late morning over the northern Great
Lakes region and the NAM this afternoon over central Wisconsin.
Northwest flow aloft does become more established while 500 mb temperatures
cool a little and a subtle vorticity drops southward as well. Cumulus rule
indicates a period of scattered- broken clouds for part of the day where
surface dewpoints linger in the middle or upper 50s. Sat imagery
showing some patchy middle level clouds over northern Great Lakes
region drifting southward. Certainly possible a lone shower could
develop today with the cooling middle levels and any lingering
surface dewpoints in the middle 50s. Since the chance is minimal will
continue with the dry forecast.

Long term...Thursday night through Tuesday
issued at 215 am CDT Wednesday Jul 23 2014

Western ridge will dominate the weather pattern during the period.
Upper level disturbances dropping southeast in the mean flow will
bring chances for showers and storms from time to time from Thursday
night into early next week.

System for Thursday night and Friday is expected to push a little
further east than previous runs...although some big difference in
model solutions on where system will track across the region on
Friday. Did raise rain chances Thursday night and Friday.

Upper trough is expected to move into the western lakes Saturday
night...then move across the region Sunday into Sunday night. This
feature will bring mostly cloudy skies along with a chance of showers
and thunderstorms. Temperatures Sunday should be below normal due
to cloud cover and rain. Below normal temperatures will continue
to run a few degrees below normal early next week. Only minor
tweaks to the forecast after Friday.

Aviation...for 18z taf issuance
issued at 1247 PM CDT Wednesday Jul 23 2014

Expect VFR ceilings across much of the forecast area the
rest of the day...with the exception of locations downwind from
Lake Michigan and the Bay where there may be VFR ceilings at
times...but mainly scattered cloud cover.

Winds will die off quickly due to the loss of daytime heating and
a weak gradient around an approaching surface high. Considering
the fact that fog developed last night/this morning in northern
Wisconsin it seems likely that there will be fog issues in central
and north central Wisconsin tonight. Have some IFR visibilities in fog at
times in tafs for grb/atw/osh/mtw...prevailing IFR visibilities in
auw/County Warning Area tafs...and prevailing LIFR at rhi during the night.
Getting fog forecasts correct if tricky but confidence level in
this forecast is medium.

Grb watches/warnings/advisories...


Short term.....Tdh
long term......eckberg

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