Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 141037
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
537 AM CDT Tue Aug 14 2018

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Wednesday
Issued at 257 AM CDT Tue Aug 14 2018

The main concern for today through Wednesday will be the
chances of showers and thunderstorms. For today, a cold
front is expected to drop southward into northern Wisconsin
this afternoon. The front is expected to trigger scattered
showers and thunderstorms across the north, as models indicating
500 to 1000 J/KG of cape during the peak heating of the day. The
Storm Prediction Center (SPC) has the area in general thunder
today, thus not expecting severe weather. There could be a few
strong storms with gusty winds, small hail and brief heavy rain.
Models indicating much of the convection should wane by mid
evening with much of the activity staying north of a Wausau to
Sturgeon Bay line. The combination of the front/outflow boundaries
from the afternoon convection is expected to produce a southward
surge of the front across northeast Wisconsin. As the front pushes
southward later this evening and overnight, kept a small chance of
showers with this feature. There will probably be some fog at most
locations late tonight. Went a degree or two above mos guidance
values for high temperatures today based on what has happened the
last two days.

On Wednesday, the boundary should set up across central into east-
central Wisconsin. Daytime heating should cause more showers and
storms to form with some additional activity north of the front
across north-central Wisconsin. High temperatures Wednesday will
be highly dependent if we see some sunshine. Despite the boundary
dropping into the area, little relief in the humid conditions. Did
increase high temperatures a degree or two at most places, except
across the far north.

.LONG TERM...Wednesday Night Through Monday
Issued at 257 AM CDT Tue Aug 14 2018

Main highlights for the long term include chances for
showers/storm? to start the period, mainly dry for the weekend,
with a better chance for widespread showers/storms early next
week. Temps look to start off near normal on Thursday, then return
to above normal for much of the rest of the period. Cooler air
does look to arrive early next week behind a low pressure system.

Wednesday night into Thursday night, surface low pressure and a
mid-level shortwave will track across Lower Michigan, while
another shortwave trails across Minnesota and Iowa, with a broad
upper trough over the Great Lakes. The heavier precip looks to
stay south/east of the area, but will need to carry slights/chance
POPs through the period, highest during the late morning and
afternoon hours of Thursday as a little instability could lead to
an increase in activity, along with some rumbles of thunder. By
Friday morning, the surface low will be in eastern Ontario, with
the upper trough over Wisconsin. The bulk of the precip is once
again expected to stay to our south, closer to the shortwave
energy, weak surface low over Iowa, and deeper moisture, but look
for some diurnal clouds (along with some high clouds) and possibly
a few showers, especially over the south/west.

As the upper trough exits to the east Friday night into Saturday,
the chances for showers will end, with ridging building into the
western Great Lakes. The dry weather looks to last into Sunday,
then attention turns to a digging trough and developing surface
low pressure over the Plains. Still a little to early to dive into
the details with this system as there remains significant
differences among the models, specifically where/when the system
deepens/tracks, which will impact where the best chances for
storms and heavy rain will occur. That said, the models have
trended toward a stronger, wrapped-up system somewhere in the
Great Lakes region early next week, likely bringing a period of
very unsettled weather to the area.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 536 AM CDT Tue Aug 14 2018

A few pockets of fog were noted across central and north-central
Wisconsin early this morning. Any fog should burn off by 13z.
For today, high clouds will stream across the area this morning.
Showers and thunderstorms are expected to develop across
northern Wisconsin this afternoon and continue into the
evening. Will have a tempo group in for the KRHI taf site.
For KAUW/KCWA, current model data has the showers and storms
on the doorstep early this evening before showers and storms
dissipate by mid evening. May have a small tempo group early
this evening for showers and storms at those two sites. KGRB,
KATW and KMTW should remain dry as the showers and storms end
across the north during the evening. After 05z, areas of fog
should develop especially across the north where it is expected
to rain. More showers and storms are in the forecast for late
Wednesday morning and afternoon.

&&

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

$$

SHORT TERM.....Eckberg
LONG TERM......Bersch
AVIATION.......Eckberg


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