Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 141129

Area Forecast Discussion
National Weather Service Green Bay WI
629 AM CDT FRI OCT 14 2016

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Saturday
Issued at 258 AM CDT Fri Oct 14 2016

As high pressure continues to shift east, return flow will
increase during the day. The corresponding WAA will cause patches
of mid-level clouds to develop through the day. WAA and periods
of sunshine will allow temperatures to warm into the middle 50s
to lower 60s.

Continued WAA on the nose of 45 to 50 kt LLJ will bring increasing
clouds and a small chance of showers to our northwest counties
late tonight. RH timesections suggest that stratus may develop
overnight, especially over the northwest half of the CWA. Steady
south winds will bring mild air into the region, leading to very
pleasant low temperatures in the lower to middle 50s.

On Saturday, a cold front will work its way into northwest WI
late in the day. Although the front and best upper level forcing
will remain to our northwest, increasing moisture (PWATS around
1.25 inches) and weak elevated instability (H8 LI`s of zero to
-2) should lead to scattered shower and isolated thunderstorm
development, especially over the northwest half of the forecast
area. Stratus clouds should continue to expand eastward during
the day.

.LONG TERM...Saturday Night Through Thursday
Issued at 258 AM CDT Fri Oct 14 2016

Mean flow is expected to gradually transition from a western NOAM
upper trough/eastern NOAM upper ridge through early next week, to
a western NOAM upper ridge/east-central NOAM upper trough by the
middle of next week. For northeast Wisconsin, initial west-
southwest flow aloft will keep an active, but mild pattern through
Tuesday before the flow turns northwest aloft and drier, cooler
air arrives. Main forecast challenge remains timing of
precipitation events this weekend into early next week.

Cold front is forecast to reach central Wisconsin toward midnight,
then sweep east of the forecast area during the overnight hours.
Models continue to show MUCAPES approaching 500 J/KG across
central Wisconsin with LI`s to around -1, along with bulk shear
values greater than 30 knots. Expect sufficient lift from the
cold front to combine with increasing mid-level forcing from a
northeast- moving shortwave trough to produce a band of showers
and thunderstorms across the forecast area. The risk of any severe
storms looks minimal at best due to the loss of daytime heating
and some convective inhibition shown on the models/forecast
soundings. Possibility of a stronger storm is there, especially
over central Wisconsin where instability to be a little stronger
Saturday evening. Min temperatures to range from around 50 to the
lower 50s north, upper 50s to around 60 east-central Wisconsin.

The cold front is progged to stall in the vicinity of the
Wisconsin-Illinois border on Sunday as weak high pressure moves
across Ontario. Exactly where this front does come to a halt will
determine how much sunshine central/east-central Wisconsin will
see, let alone the outside minimal chance of a shower late in the
day. Have kept the vast portion of the forecast area dry on Sunday
with max temperatures in the mid 60s north-central, 65-70 degree
range elsewhere.

Models indicate an increasing south-southwest low-level jet (up to
50 knots) will lift the stalled boundary north as a warm front
Sunday night and couple with a weak shortwave trough to bring the
next chance of showers/thunderstorms to northeast Wisconsin. We
will also have to watch for a few stronger storms again as MUCAPES
could approach 1K J/KG and mid-level lapse rates reach 7 C/KM.
However, potential of convective inhibition could keep these
storms in check. Min temperatures to be in the upper 40s far
north, middle 50s south. Monday could very well be the warmest day
of the extended forecast as a southerly flow to continue into
Wisconsin with 8H temperatures reaching around +15C. Northeast
Wisconsin to reside between one weather system pulling away into
southeast Canada and the next system organizing over the Northern/
Central Plains. Depending on the amount of sunshine we receive,
temperatures over central/east-central Wisconsin (away from Lake
MI) could get into the lower 70s.

There are still questions associated with this next system headed
into Monday night, primarily with the location/movement of an area
of low pressure. Models remain inconsistent from run-to-run, thus
confidence is somewhat lacking. A pretty strong shortwave trough
is forecast to lift northeast across the Northern Plains Monday
night, thus a more northern track of the low pressure makes more
sense. If this is the case, the stronger lift/forcing would pass
to our west and north Monday night into Tuesday with only the
passage of a cold front to initiate any precipitation over the
forecast area. Prefer to place higher pops over northern Wisconsin
during this time with lower pops farther south. One more mild day
expected on Tuesday with max temperatures close to 10 degrees
above normal.

By the middle of next week, the mean flow will be transitioning
toward a western NOAM upper ridge/east-central NOAM upper trough
pattern. Weak high pressure should keep northeast Wisconsin dry on
Wednesday, but it will be noticeably cooler with temperatures
closer to normal which translates to lower to middle 50s north,
mainly upper 50s south.

As the broad mid-level trough settles over east-central NOAM by
next Thursday, combination of cool air aloft/daytime heating along
with the passages of individual shortwaves, could generate
sporadic light precipitation chances. Max temperatures on Thursday
should be cool with readings around 50 north, lower to middle 50s

.AVIATION...for 12Z TAF Issuance
Issued at 620 AM CDT Fri Oct 14 2016

A band of altocumulus clouds will push through northeast WI early,
otherwise skies should be clear to partly cloudy today. Gusty
south winds will develop by around midday.

Aviation concerns will increase quickly tonight, as LLWS develops
in the evening, and continues overnight. In addition, stratus
clouds will spread into central and north central WI in the late
evening, and into eastern WI toward daybreak. When the stratus
first arrives, cigs should be generally in the MVFR category,
but should lower into the IFR/LIFR category over north central
and central WI late.


Issued at 258 AM CDT Fri Oct 14 2016

Have decided to upgrade the Small Craft Advisory on the northern
Bay and northern Lake Michigan zones to a Gale Warning, as gusts
to 35 kts appear likely. 925-850 mb winds are expected to be 40 to
45 kts, and water temperatures in our northern marine zones are
still 17-18 C, so mixing should occur. For the sake of simplicity,
the Gale warning headlines (19z/Fri-03z/Sun on the northern Bay,
and 19z/Fri-09z/Sun on northern Lake Mich) will encompass the
ramp up and ramp down periods of Small Craft conditions at onset
and the end of the event.

Frost Advisory until 9 AM CDT this morning FOR WIZ022-038>040-


SHORT TERM.....Kieckbusch
LONG TERM......Kallas
MARINE.........Kieckbusch is the U.S. government's official web portal to all federal, state and local government web resources and services.