Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 181636
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1136 AM CDT Sun Jun 18 2017

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Monday
Issued at 403 AM CDT Sun Jun 18 2017

A potent short-wave trof was moving through Wisconsin early this
morning, and producing widespread moderate to briefly heavy
rainfall. Little lightning has been observed over the past couple
hours, but that may change soon as forcing increases over east
central WI, where CAPE is still around 600 j/kg in the warm sector
just east of a 998 mb surface low.

The main area of rain will gradually lift northeast out of the
region this morning. Will carry likely/categorical pops over
northern WI. Cyclonic northwest flow and additional short-wave
energy will trigger more showers and thunderstorms this afternoon,
most numerous over northern WI. Small hail may accompany any
storms. It will be much cooler and turning blustery, with highs
only reaching the middle 60s northwest to the lower to middle
70s southeast.

Expect most of the lingering convection to diminish after sunset
tonight, with mainly dry conditions overnight. Low temperatures
will settle into the upper 40s and 50s.

On Monday, weak short-wave energy and an associated secondary
cold front will impact the area, bringing additional chances of
showers and thunderstorms. Will carry the highest pops over the
southeast half of the forecast area in the afternoon, as the
best instability (CAPE around 500-1000 j/kg) will reside there.
Once again, with cold air aloft and low wet-bulb zero heights,
small hail will be likely with any storms. High temperatures
will range from the middle 60s to the lower 70s.

.LONG TERM...Monday Night Through Saturday
Issued at 403 AM CDT Sun Jun 18 2017

Upper level flow starts off northwest and then backs to a more
zonal pattern around the middle of the week before becoming
southwest ahead of an approaching trough that is expected to be
moving into the region next weekend.

There is at least a slight chance for showers and thunderstorms
Monday night and Tuesday in cyclonic flow both aloft and at the
surface. A surface ridge passing through Wisconsin should help to
keep Tuesday night dry, but an approaching warm front then brings
chances for showers and storms back to the area starting Wednesday
and continuing into Wednesday night. 00Z models have high pressure
over the region on Thursday so it looks mainly dry. Timing beyond
that gets to be quite a challenge, so have opted to use the 00z model
blend for PoPs the rest of the way through the forecast.

Below normal daytime temperatures are expected on Tuesday but a
slight warming trend, as upper flow backs, will bring near normal
highs to the area for Thursday and Friday before slightly cooler
than normal temperatures arrive for Saturday.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1129 AM CDT Sun Jun 18 2017

Steady rains are ending over far northeast Wisconsin late this
morning, but areas of MVFR ceilings will persist for several
hours into the afternoon. Scattered showers and a few
thunderstorms will redevelop across the region through early
evening. Expect a fairly quiet night after sunset with showers
diminishing, but low clouds are expected to develop over mainly
north central and far northeast WI later tonight. More showers are
anticipated to develop by late Monday morning.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....Kieckbusch
LONG TERM......MG
AVIATION.......MPC



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