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Area forecast discussion
National Weather Service Green Bay WI
1146 PM CDT sun Oct 13 2019

Updated aviation portion for 06z taf issuance

issued at 601 PM CDT sun Oct 13 2019

Latest satellite trends continue to point toward clearing skies
from the northwest this evening. Temperatures are already in the
30s across much of the area and are expected to continue dropping
into the low 30s by daybreak. Some light wind may linger into the
overnight hours, which could limit frost development in exposed
locations; however, temperatures falling close to or possibly
below freezing could still pose a hazard to vegetation in those
locations. A little tricky from a messaging standpoint. Decided to
issue the frost advisory and word it so that isolated freezing
conditions may also develop, even in the locations that don't
experience frost development.

Short term...tonight and Monday
issued at 218 PM CDT sun Oct 13 2019

Scattered rain showers mixed with snow at times, was moving across
central and northeast Wisconsin. The precipitation was mainly in
the form of snow across north-central Wisconsin. It was a cold
October afternoon with temperatures in the middle 30s north
to the lower 40s south.

For tonight, main concern is for freezing temperatures across
the Fox Valley east to the lake. Numerical guidance has been
too warm the last few nights, thus lower than normal confidence
in temperatures reaching the freezing mark. Decided to issue
a Special Weather Statement (sps) to highlight the low
temperatures near or slightly above freezing for the Fox Valley
east to the lake where frost/freeze headlines are still being
issued. Clouds will be on the decrease tonight, especially across
eastern Wisconsin while the clouds are expected to remain across
north-central into central Wisconsin. The rain/snow showers should
come to an end by mid evening.

On Monday, it should start mostly cloudy across the north with
decreasing clouds through the day. Partly cloudy skies will
prevail across the remainder of the region. Did not stray far
from numerical guidance for high temperatures. It will remain cool
with high temperatures running 10 to 15 degrees below normal.

Long term...Monday night through Sunday
issued at 218 PM CDT sun Oct 13 2019

The start of the long term forecast remains in a cooler and
somewhat active weather pattern, with the primary focus on Tuesday
into Tuesday night. A warmer weather setup is expected by the end
of the week.

Monday evening through wednesday: expect at least partial clearing
at the start of Monday night, then with fading influence from the
ridge cloud cover will increase with a chance for light
precipitation across central Wisconsin near daybreak.

Tuesday becomes the main period of interest in the long term
forecast as a strong mid-level shortwave and surface low approach
WI from the west. Rain is the main precip type, however a brief
period of mixed precip or light snow showers are possible across
northern WI at the onset and again as the system pulls away.
Expect pcpn to develop from west to east across the forecast area
Tuesday morning with the primary push of warm air advection ahead of the sfc low.
Forcing is strong but the window of opportunity is short- lived.
Showers will become more widely scattered to isolated during the
afternoon as a dry slot wraps up into the area. A few claps of
thunder cannot be ruled out Tuesday afternoon as models continue
to show around 100 to 200 j/kg of cape across central and east-
central WI (coinciding with the spc's day 3 general thunder
outlook). Lingering rain and/or snow showers are possible Tuesday
evening through Wednesday morning due to wrap around moisture
coming back across northern Wisconsin and northwest winds over Lake
Superior. This activity should remain light and scattered. No snow
accumulations are forecast. Rain amounts during this are forecast
to range from a few hundreths across central and east- central WI,
to up to half an inch across far northern Wisconsin.

Rest of the week/weekend: a pattern shift is still on pace to
begin Thursday as surface and upper level ridging take place and
southerly winds help drive a warmer airmass into the state. Highs
will be near 50 degrees on Thursday, then in the mid 50s to low
60s on Friday through the weekend. Rain is possible later Friday,
Saturday, and again on Sunday, but confidence is low at this time
due to model differences and consistency.

Aviation...for 06z taf issuance
issued at 1141 PM CDT sun Oct 13 2019

An upper-level low and surface low slowly working through the
area tonight, will shift off to the east through the day Monday.
Occasional MVFR conditions may impact rhi and may drop as low as
IFR at times. This will largely be due to a shortwave sliding
through the area along with some upslope winds/moisture into the
site. Otherwise, steadily improving conditions and decreasing
winds can be expected throughout Monday through Monday night.

Grb watches/warnings/advisories...
frost advisory until 9 am CDT Monday for wiz022-038>040-048>050-


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