000
FXUS63 KGRB 242342
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
642 PM CDT Sun Jun 24 2018

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Monday
Issued at 247 PM CDT Sun Jun 24 2018

A fairly quiet summer afternoon across the area so far, with some
high clouds drifting across the region and daytime cumulus
clouds over much of the area, away from Lake Michigan. The
thickest cloud cover was over central WI where a little more
moisture was present and temps reached the convective temp (upper
70s to 80). Only a couple returns on the radar in our area with no
lightning detected as of 2:45pm. The cumulus field doesn`t look
very agitated just yet overall, but starting to see areas of some
beefier clouds, especially in Wood/Portage counties.

For this evening, look for the high clouds to continue to spread
across the region. The daytime cumulus clouds will slowly
dissipate as the evening progresses. There is still a window for
showers to develop late this afternoon/early evening, mainly
across central and north central WI. Meso models continue to focus
on an area from Oneida/Lincoln to Forest county as the best chance
to see some activity, possibly into Marathon, along/near a weak
surface boundary. A couple showers are expected over Wood and
Portage counties as well. A rumble of thunder is also possible,
but instability is lacking (SBCAPEs of 400-800 J/kg), plus some
weak surface-based convective inhibition (CIN) to overcome. Will
linger some chance POPs in the evening, then go dry overnight as
instability wanes.

Dry conditions are expected on Monday as weak high pressure/
ridging pushes over the region and some drier air filters in
from the east/northeast. Some sunshine is expected in the morning
(possibly filtered by high clouds), then look for thicker clouds
to work into the area in the late morning and afternoon as the
next system approaches from the west, along with possibly some
daytime cumulus clouds.

.LONG TERM...Monday Night Through Sunday
Issued at 247 PM CDT Sun Jun 24 2018

A relatively small, but vigorous low pressure system will deliver
rain and thunderstorms to northeast Wisconsin on Tuesday. While
this system has potential to produce severe weather, most of that
activity should stay south of the Fox River Valley, as easterly
winds drawn across the cool waters of Lake Michigan ahead of the
approaching low will help reduce instability.

Forecast concerns mainly revolve around precipitation chances
this week, followed by heat concerns from Thursday on into the
weekend. Over the past couple of days, medium-range forecast
trends have placed the development of a beefy sub-tropical ridge
further east into the northeast U.S. This trend is more favorable
for mesoscale convective system activity across the western Great
Lakes, but so far models are not in good agreement on timing and
location of said systems. If not for the potential of thunderstorm
activity, highs on Friday and Saturday could approach 90 in the
north and the mid 90s over central and east- central WI. Heat
indices could also approach dangerous levels if cloud cover and
precipitation are absent.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 642 PM CDT Sun Jun 24 2018

VFR conditions are expected through Monday, with scattered middle
and high clouds. Showers and thunderstorms and MVFR/IFR conditions
are expected late Monday night and Tuesday as a front approaches.
&&

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

$$

SHORT TERM.....Bersch
LONG TERM......ML
AVIATION.......RDM

NWS GRB Office Area Forecast Discussion