Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 111721
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1221 PM CDT Fri Aug 11 2017

Updated aviation portion for 18Z TAF issuance

.SYNOPSIS...
Issued at 342 AM CDT Fri Aug 11 2017

Relatively quiet late summer weather through at least early next
week.

The upper flow at high latitudes across North America will become
increasingly blocky through early next week. That will leave the
southern portion of the large scale trough currently across the
area in place for much of the forecast period. The blocking will
increasingly become confined to high latitudes later next week,
which will allow a fairly zonal band of westerlies to develop
across southern Canada and the northern CONUS.

After below normal temperatures today, readings will gradually
trend upward, likely to modestly above normal by the latter part
of next week. Humid conditions will probably return to the area
late in the period as well. There will be limited opportunities
for precipitation through early next week, then rain chances will
increase. Precipitation totals for the period are likely to end
up below normal unless significant rains arrive late in the
period.
&&

.SHORT TERM...Today...Tonight...and Saturday
Issued at 342 AM CDT Fri Aug 11 2017

Much quieter today. Some fog and drizzle will probably linger
across the north early. Radar has been showing some patchy returns
out of the mid-deck passing through east-central Wisconsin, so
will cover that with a mention of sprinkles. As far as the
potential for showers later today, support for that is pretty much
confined to the ECMWF and GFS. Decided to maintain low PoPs to
cover the possibility, though confidence in getting anything at
all isn`t great.

Clearing skies and diminishing winds tonight should allow temps to
fall off pretty well in the climatological cool spots of central
and north-central Wisconsin. Took mins below guidance in those
locations. There should be a little wind across the rest of the
area, so stayed close to a blend of the top performing guidance
products elsewhere.

Plenty of sunshine and a dry air mass should allow temperatures to
rebound to within a couple degrees of normal Saturday. Nudged
maxes to match the better performing guidance products, which
were a bit warmer than the broad-based blend.

.LONG TERM...Saturday Night Through Thursday
Issued at 342 AM CDT Fri Aug 11 2017

This part of the forecast is generally dry with near or slightly
above normal temperatures as surface high pressure remains in the
region through early next week. Showers are possible at some
point over the weekend as a mid level trough axis passes through
Wisconsin, but models had their differences and the blended
solution brought just a slight chance for showers to parts of
central and east central Wisconsin and confined it to Sunday
afternoon.

The next chance for showers and thunderstorms will be Wednesday
night and Thursday as the high starts to move away from Wisconsin
and mid level short wave energy enters the picture. Models differ
in their timing and location of the best upper support, but right
now it appears that rain chances are higher in north central and
northeast Wisconsin than in the central and east central parts of
the state. The 00Z GFS had PWATs of 1.5 to 2 inches in the
forecast area for Thursday so there is the potential for heavy
rainfall, if it verifies well.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1221 PM CDT Fri Aug 11 2017

Cyclonic flow over northeast Wisconsin will continue to linger
MVFR cigs over much of the area for the start of the afternoon.
High pressure with drier air on northwest winds building into the
state from the west will decrease clouds and raise ceiling heights
to VFR from west to east during the afternoon hours. Clearing
skies and light winds tonight may lead to patchy fog late. VFR
conditions are expected for Saturday.
&&

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

$$

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



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