Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 141657
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1157 AM CDT Mon Aug 14 2017

Updated aviation portion for 18Z TAF issuance

.SYNOPSIS...
Issued at 421 AM CDT Mon Aug 14 2017

Some showers today and tonight, otherwise mainly seasonable
temperatures for the upcoming week.

During the forecast period, the flow across North America will
consist of a blocky pattern at high latitudes, with a modest,
progressive band of westerlies to the south across southern
Canada and the northern CONUS. Temperatures will be mainly near to
a little above normal, though there will probably be a day or two
with slightly cooler temperatures. A couple rather humid days are
likely mid-week as well. There will be sufficient opportunities
for precipitation to result in AOA amounts for the period.
&&

.SHORT TERM...Today...Tonight...and Tuesday
Issued at 421 AM CDT Mon Aug 14 2017

The eastward progression of the precipitation with the incoming
shortwave continues to be slower than indicated by the models. In
addition, some of short-range models are now showing somewhat
limited coverage across the area later today. Adjusted PoPs based
on short-term extrapolation of radar trends, interpolated back
into consensus model PoPs for later today. Still think most areas
will get some rain, but did not take PoPs above likely at any
location due to concerns over coverage. Enough destabilization
will probably occur to get some thunderstorms this afternoon into
this evening, though severe storms seem unlikely. Also raised PoPs
from the previous forecast into the overnight hours to account
for the slower eastward progression of the system. PWATs will
generally be in the 1 to 1.5 inch range, with surface dew points
in the lower 60sF. Those values are pretty modest for this time of
year, so although a few of the storms could produce brief
downpours this isn`t really a heavy rainfall situation.

Some fog may develop across the north late tonight, depending
upon how quickly the clouds exit the region.

Northeast flow may keep temps a degree or two below normal
Tuesday, but the air mass across the area will be seasonable.
Stayed close to a blend of guidance products for high
temperatures.

.LONG TERM...Tuesday Night Through Sunday
Issued at 421 AM CDT Mon Aug 14 2017

Timing of precipitation chances is the main concern during this
part of the forecast.

An approaching mid level short wave trough and surface low moving
out of the Plains will bring a slight chance for showers and
thunderstorms to central Wisconsin late Tuesday night. Chances
for showers and storms increase across the area as these features
approach and then move across Wisconsin. Showers are likely,
along with some thunderstorms, for the entire forecast area on
Wednesday night. PoPs then drop off as the surface and upper
systems depart, leaving mainly dry weather from Thursday afternoon
through Friday evening. Showers are possible with the next system
that is expected to impact the region mainly in central Wisconsin
late Friday night into Saturday. Timing and strength of the
system are not consistent among the models so forecast confidence
is low.

High temperatures should be within a few degrees of normal at
most locations from midweek into the upcoming weekend.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1151 AM CDT Mon Aug 14 2017

Scattered showers and isolated storms will continue to move east
across the area for the rest of the afternoon into this evening.
Ceilings should continue to hold up well this afternoon, though
could drop locally to mvfr within the heavier showers/storms.
Short range models continue to show that showers will diminish
this evening. But ample mvfr clouds upstream and statistical
guidance suggest ceilings will lower overnight. Any ifr/mvfr cigs
to improve quickly on Tuesday morning after 14-15z.

&&

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

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Skowronski
LONG TERM......MG
AVIATION.......MPC



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