Area Forecast Discussion
Issued by NWS Green Bay, WI

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867
FXUS63 KGRB 221935
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
235 PM CDT SUN MAY 22 2016

Forecast discussion for routine afternoon forecast issuance

.SYNOPSIS...
Issued at 234 PM CDT Sun May 22 2016

The upcoming work week will bring a change to a much wetter
weather pattern, but with temperatures generally remaining above
normal.

The large scale flow in the middle latitudes across NOAM is
currently dominated by troughs over the West and East, with a
sharp ridge in between near 90W. Changes to the large scale
pattern will occur the next few days as shortwave energy shearing
out of the western trough gradually flattens the mid-continent
ridge and nudges it east. That will result in the development of
southwest flow across the forecast area. Once in place, the
southwest flow is likely to persist through next weekend.

Southwest upper flow at this time of year favors mild, wet, and
increasingly humid weather across the forecast area. The specifics
of the precipitation chances will be dependent on the location of
the main frontal boundary and timing of small scale shortwaves
riding northeast from the Plains. Amounts are likely to end up
above normal for the period. Though individual daytime
temperatures will vary depending on clouds and precipitation,
readings are expected to average above normal for the period. The
chilly nighttime temperatures will come to an end as the air mass
moistens.
&&

.SHORT TERM...Tonight and Monday
Issued at 234 PM CDT Sun May 22 2016

Another warm and dry was noted across the area with temperatures
in the upper 70s to middle 80s. Relative humidity values dropped
to 15 to 30 percent away from the bay and lake. For tonight, clear
skies will prevail with lows in the middle 40s to lower 50s.
Followed the ADJECSBC guidance for lows since it has performed
well the last few nights.

On Monday, it will be warm and dry with highs in the lower to
middle 80s with afternoon relative humidity values dropping to
18 to 33 percent. South winds are expected to increase to 10 to
20 mph, with gusts of 20 to 30 mph. Followed the ADJECSBC/ADJMETBC
guidance for highs on Monday. Any rain should hold off until
Monday night.

.LONG TERM...Monday Night Through Sunday
Issued at 234 PM CDT Sun May 22 2016

Once again today, the main long-term forecast challenges are
the timing of precipitation chances and assessing the potential
for severe weather.

The main change in the guidance since yesterday is for the main
frontal boundary to surge southward more quickly. Some additional
slowing of the initial influx of precipitation was also noted on
the 12Z guidance. As a result, slowed the eastward progression of
the PoPs Monday night a bit more, especially early in the night.
The latest guidance changes also suggested a lull in the
precipitation (or possibly even a dry period) Tuesday night.
Trended the forecast in this direction. But forecast details are
especially hard to pin down in southwest flows like the one that
is developing, so kept the changes modest in case later guidance
waffles back the other way.

The SPC focuses the primary severe weather risk south of the area
during later outlook periods. That seems reasonable given the
likely position of the main frontal boundary. It still appears a
somewhat stronger/better defined shortwave will approach the area
Wednesday afternoon and then cross the area Wednesday night. That
could bring a risk of severe weather to the area, depending on
whether or not the main frontal boundary can lift back north
toward the area in prior to it`s arrival. But as yesterday,
nothing about the set-up appears especially ominous at this point.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1155 AM CDT Sun May 22 2016

VFR conditions will continue through 00z Tuesday. For later
tonight, added low level wind shear to the KRHI/KAUW/KCWA
tafs. Southerly winds around 700 feet are expected to crank up
to around 30 knots late this evening into the overnight hours.
Winds will increase at the surface late Monday morning and
continue into early Monday evening. Winds should gust between 15
and 25 knots, with locally higher gusts over portions of north-
central and far northeast Wisconsin. The next chance for showers
and thunderstorms will be on Monday night and Tuesday.
&&

.FIRE WEATHER...
Issued at 234 PM CDT Sun May 22 2016

Elevated fire weather conditions will prevail through mid-evening
until temperatures fall back into the 60s and relative humidity
values rise above 50 percent. Another warm and dry day is expected
on Monday, with high temperatures in the lower to middle 80s and
afternoon relative humidity values of 20 to 30 percent away from
the bay and lake. The only difference between Monday and the last
two days will be the wind. Winds are expected to increase to 10 to
20 mph by late Monday morning and continue into early Monday
evening. Wind gusts of 20 to 30 mph are also expected during this
period. The combination of the warm and dry weather along with the
gusty winds will create critical or near critical fire weather
conditions. A fire weather watch has been issued for locations
generally north of a Merrill to Oconto line. Showers and thunderstorms
are expected across much of the area Monday night or Tuesday that
will reduce the risk of wild fires.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Monday afternoon through Monday evening
FOR WIZ005-010>013-018>021-073-074.
&&

$$

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



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