Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 121717
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1217 PM CDT Sat Aug 12 2017

Updated aviation portion for 18Z TAF issuance

.SYNOPSIS...
Issued at 331 AM CDT Sat Aug 12 2017

Quiet late summer weather through at least early next week.

Increasingly blocky flow across North America at high latitudes
will lock the gradually weakening remnants of the eastern trough
in place across the Great Lakes region into next week. But the
blocking will become increasingly confined to high latitudes
later next week as a fairly zonal band of westerlies develops
across southern Canada and the northern CONUS.

The modified polar air mass across the area early in the period
will be dry, but a return to more humid conditions is expected by
the middle of next week. Overnight lows will fall to seasonably
cool levels early while the dry air dominates, then likely remain
AOA normal as the humidity increases. Daytime highs will
generally be near to modestly above normal during the period. The
main opportunities for precipitation will be Monday and again
during the middle to latter part of next week. Moisture will be
limited with the initial system, but later systems could be more
robust precipitation producers. Precipitation totals for the
period will depend heavily on what falls late in the period. The
best guess is for near normal amounts, though confidence in that
forecast is low.
&&

.SHORT TERM...Today...Tonight...and Sunday
Issued at 331 AM CDT Sat Aug 12 2017

A band of middle clouds dropping southward through eastern
Wisconsin was generating some weak returns on area radars, so
carried sprinkles over portions of the east for a time this
morning. Otherwise, some (though limited) convective cloudiness
should develop during the day, and dissipate tonight. Then clouds
will increase as a mid-level shortwave approaches from the west.
At this point, expect the air mass associated with lingering high
pressure to be too dry to allow for any precipitation.

Stayed close to a broad based-blend of guidance for highs today
and Sunday. Lows tonight were a little trickier. PWATS will be
higher than this morning, and there will probably be some cirrus
streaming across the area. But low-level winds will probably drop
to calm due to the high directly across the area. Lowered mins
from the previous forecast, close to a blend of the better
performing bias-corrected guidance products. That may be cool
enough to allow for patchy fog to form, so added that as well.

.LONG TERM...Sunday Night Through Friday
Issued at 331 AM CDT Sat Aug 12 2017

Return flow behind a departing surface high pressure system and a
mid level trough will bring a chance for showers and thunderstorms
to most of the area on Monday. The next chance for showers and
thunderstorms starts to move in Tuesday night and spreads across
most of the area on Wednesday as a surface system and mid level
short wave pass through the region. Models were not all that
consistent by this point so forecast confidence is a bit on the
low side. There is another chance for showers and storms on Friday
but models differ quite a bit by this time so this part of the
forecast is questionable at best.

High temperatures should generally be near or above normal during
the upcoming work week.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1121 AM CDT Sat Aug 12 2017

Other than areas of patchy fog possibly resulting in isolated
IFR/LIFR conditions late tonight, good flying conditions are
expected through the taf period.

&&

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

$$

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



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