Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 231931
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
231 PM CDT MON MAY 23 2016

Forecast discussion for routine afternoon forecast issuance

.SYNOPSIS...
Issued at 230 PM CDT Mon May 23 2016

A change to a much wetter weather pattern, but with temperatures
generally remaining above normal.

The sharp upper ridge which brought several warm and dry days to
the area is gradually breaking down and shifting east. But the
upstream trough over the western CONUS is expected to remain in
place. The result will be the development of southwest upper flow
across the forecast area. Once in place, the southwest flow is
likely to persist at least through next weekend.

The southwest flow will bring mild temperatures and considerable
precipitation. Although the specifics of the precipitation
chances will be hard to ascertain, it is very likely that amounts
for the next 7 days will be above normal. Daily temperatures will
vary depending on amount of clouds and precipitation, but readings
are expected to be at or above normal.
&&

.SHORT TERM...Tonight and Tuesday
Issued at 230 PM CDT Mon May 23 2016

Another warm day was noted across the region with temperatures in
the lower to middle 80s away from the bay and lake. Afternoon
relative humidity readings at most places dropped into the 20 to
30 percent range. Winds gusted as high as 35 mph across portions
of north-central Wisconsin.

For tonight, a cold front will approach from the west. Showers
and thunderstorms will move into north-central and central
Wisconsin this evening. Some of the storms may be capable of
producing gusty winds and small hail. The showers and storms will
struggle into eastern Wisconsin due to the dry air mass in place.
The lake shore region may not see any rain until after 7 am.
Took a blend of the guidance tonight due to cloud cover and
persistent south winds.

On Tuesday, the frontal boundary will sag south across the area.
Bufkit soundings indicated close to 1000 j/kg, total totals of 50
to 55, and low wet bulb heights from 8500-9500 feet at Green Bay.
If we can get ample sunshine, some of the stronger storms could
produce strong gusty winds and hail. An isolated severe storm
could not be ruled out.

.LONG TERM...Tuesday Night Through Monday
Issued at 230 PM CDT Mon May 23 2016

Long-term forecast challenges continue to be the specifics of the
precipitation chances, and the risk of severe weather.

As typical for a southwest flow regime where precipitation chances
are tied to fairly small scale shortwaves, the details of the
precipitation forecast look a little different again today.
Frontal boundary is still expected to sag south across the area
Tuesday night, but upper support for precipitation during that
time will be limited. So will continue to have a lull in the
precipitation chances Tuesday night. Precipitation chances will
increase from the southwest Wednesday, as isentropic lift over the
frontal boundary increases and a mid-level shortwave approaches
from the southwest. Maintained the likely PoPs we have been
carrying in the forecast for Wednesday night, then tapered back to
chance PoPs for Thursday as the shortwave shifts off to the
northeast. Another significant round of precipitation is likely
early in the weekend as another significant shortwave heads across
the region. Precipitation could occur at other times as well, but
the smaller scale of the shortwaves affecting the area at those
times make timing difficult, and resulted in chance PoPs in most
periods.

As far as the severe weather threat is concerned, the SPC
continues to focus the primary severe weather risk south of the
forecast area throughout the week. That seems reasonable given
the likely position of the main frontal boundary to our south. But
given the increasingly moist and unstable airmass likely to be
across the area, it is certainly possible that the severe risk
could expand northeast into the forecast area at times. But
determining when that would occur is very difficult.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1138 AM CDT Mon May 23 2016

Very warm this afternoon with gusty southerly winds. Portions
of central into north-central and far northeast Wisconsin could
wind gusts of 30 to 35 kts. Much more stable air is expected near
the Great Lakes, where wind gusts around 20 knots are expected.
The chances of showers and thunderstorms will increase across
central into north-central Wisconsin later this evening and
continue overnight. The combination of the slow moving front and
dry air across eastern Wisconsin should allow for a much slower
arrival of the rain. The rain is not expected to reach the
lakeshore until after sunrise. Models indicated a band of showers
and storms moving across the area overnight into Tuesday morning.
There should be a break in the action, but secondary boundary
dropping south out of Upper Michigan could bring another
chance of showers and storms Tuesday afternoon into Tuesday
evening.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 8 PM CDT this evening FOR WIZ005-010>013-
018>021-073-074.
&&

$$

SYNOPSIS.......Skowronski
SHORT TERM.....Eckberg
LONG TERM......Skowronski
AVIATION.......Eckberg



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