Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 221739
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1239 PM CDT MON AUG 22 2016

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Tuesday
Issued at 346 AM CDT Mon Aug 22 2016

Little change to previous short-term forecast as surface high
pressure currently situated over the forecast area continues to
drift into the eastern Great Lakes today. Heights will continue to
rise aloft over the western Great lakes region into Tuesday ahead
of notable shortwave trough forecast to push into eastern Montana
and Wyoming by 00Z Wednesday. In response to aforementioned
upper-level trough, strengthening southwesterly low-level jet over
the plains has lead to robust WAA over the northern Mississippi
Valley. Within WAA zone, IR satellte imagery indicates expanding
area mid-level clouds and light shower activity spreading ESE
across northern Minnesota and western Lake Superior. Short-term
model guidance continues to suggest that southern edge of mid-level
cloudiness will brush the northern portion of the forecast area
this morning with very light shower activity staying well north
of the Wisconsin-Michigan border. Other than some passing mid-level
clouds across the north this morning, should see mostly sunny skies
with increasing southwesterly winds especially this afternoon as
deeper mixing begins to tap into the stronger southwest winds
aloft. Daytime highs should rebound to 75 to 80 degree range which
is close to normal for middle of August.

This evening and overnight, the majority of the model guidance
including the RAP,NAM,WRF and Canadian continue to suggest the
possibility of some isolated shower or thundershower activity
breaking out in strong WAA zone and near leading edge of steep
mid-level lapse rates over far northern Wisconsin and Upper
Michigan around 00Z. Although moisture is still somewhat paultry,
forcing associated with LLJ/WAA is fairly stout in this region.
Given fairly consistent signal among the model guidance, low-end
pops across the north this evening look pretty reasonable. Any
elevated activity that devlops this evening should push off to
the east rather quickly by daybreak Tuesday.

On Tuesday, upper heights will continue to build over the western
Great Lakes as upstream trough approaches the Dakotas. Associated
surface frontal boundary will only make it into the eastern
Dakotas by 00 UTC Wednesday. Model guidance fairly consistent on
firing convectivity activity over eastern Nebraska and eastern
Dakotas near the frontal boundary late Tuesday afternoon, with
Wisconsin remaining dry. Will start to feel a bit more humid on
Tuesday as boundary layer moisture starts to work its way back
north on brisk southwest winds.

.LONG TERM...Tuesday Night Through Sunday
Issued at 346 AM CDT Mon Aug 22 2016

Low amplitude mid level flow should lead to a period of mainly
near or above normal temperatures for this part of the forecast.
This setup does lead to some timing differences among the models
but they seem to at least be pretty close with the midweek
system.

An approaching mid level short wave and surface cold front will
bring a chance for showers and thunderstorms to the area late
Tuesday night through Wednesday evening.

Have not really made more than minor cosmetic changes to the
initial days 4 through 7 model blend. It keeps the area dry
through Friday night with surface high pressure moving into the
region, though a couple of the models did have some QPF in
northern Wisconsin during the day on Thursday.

The next system approaching the state will bring chances for
showers and storms starting Saturday and continuing through
Sunday.

The warmest days look to be the wettest with cooler, but still
near or a little above normal, temperatures Thursday into
Saturday.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1238 PM CDT Mon Aug 22 2016

Vfr conditions to prevail this afternoon and tonight as high
pressure drifts southeast of the area. Southwest winds on the
backside of the high will increase this afternoon. Increasing
southwest winds in the boundary layer may also produce low level
shear conditions over Central and North Central Wisconsin taf
sites, including AUW, CWA and RHI.
&&

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

$$

SHORT TERM.....ESB
LONG TERM......MG
AVIATION.......TDH



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