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Area forecast discussion
National Weather Service Green Bay WI
1033 PM CDT Sat Sep 14 2019

Updated aviation portion for 06z taf issuance

Short term...tonight and Sunday
issued at 227 PM CDT Sat Sep 14 2019

Clouds were on the increase this afternoon as temperatures
warmed into the middle 60s north to the lower 70s south.

For tonight, an area of low pressure and the associated warm
front is expected to lift northward. A 35 to 45 knot low level
jet is expected to develop this evening and veer overnight.
Scattered thunderstorms are expected to develop and spread
northeast across the area this evening into the overnight
as the low level jet increases to 35 to 45 knots and veers
overnight. Models indicating steep mid level lapse rates
around 6 c/km and 850 lifted indices around 0 c across central
and east-central Wisconsin to support thunderstorms. Also
noted was 0-6 km shear values of 35 to 45 knots to support
stronger storms. The new day 1 outlook from the storm prediction
central (spc) now has the entire area in a marginal risk of
severe storms. Will continue to mention stronger storms with
gusty winds and hail in the hazardous weather outlook. Will also
mention brief heavy rain as well.

Late tonight and Sunday morning, areas of fog and some light rain
or drizzle will linger past 7 am, especially across eastern
Wisconsin. Clouds will be slow to clear during the day, thus
lowered maximum temperatures on Sunday by a few degrees, which
was indicated in the latest numerical guidance values.

Long term...Sunday night through Saturday
issued at 227 PM CDT Sat Sep 14 2019

Dense fog looks to be a good bet late Sunday night
and early Monday as skies clear and winds become light over the
wet ground. A dense fog advisory might be need if this situation
does materialize.

An upper ridge is expected to move into Wisconsin Monday and
Tuesday and produce dry and mild weather with highs and lows
around ten degrees above normal. The upper flow is then forecast
to become southwest Wednesday and Thursday with a weak cold front
approaching from the plains. This will bring a good chance of
showers and thunderstorms at some point, though the models are
quite different with timing.

Upper ridging looks likely to return Friday and Saturday with
mostly warm and dry weather.

Aviation...for 06z taf issuance
issued at 1019 PM CDT Sat Sep 14 2019

A warm front moving northward will trigger showers and a few
thunderstorms overnight. The first round of showers will shift
out of far northeast WI early in the taf period, while a second
round may form over the south part of the forecast area during
the overnight hours. Ceilings should drop to MVFR overnight,
followed by periods of low stratus, fog, drizzle and IFR
conditions late tonight into Sunday morning. Conditions should
slowly improve from west to east in the late morning and
afternoon, with VFR conditions returning to the western taf sites
late in the day.

Partial clearing in the evening may allow fog to develop,
especially late in the taf period. The worst conditions will
likely occur overnight, and this will be detailed in the 12z

Grb watches/warnings/advisories...


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