Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 261126

Area Forecast Discussion
National Weather Service Green Bay WI
626 AM CDT WED OCT 26 2016

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Thursday
Issued at 332 AM CDT Wed Oct 26 2016

A swath of rain continues to advect in from the southwest early
this morning ahead of an approaching low pressure system currently
located near Omaha. This low will track through northern Illinois
later this afternoon and this evening. Abundant isentropic lift,
frontogenesis and a vigorous mid level shortwave tracking through
the western Great Lakes will bring rain to the area for much of
today and this evening, with activity slowly ending from west to
east later tonight as the low moves off to the east.

The abundant lift will take advantage of PWATs approaching 1 inch,
which should bring a widespread soaking rain of 1 to 2 inches to
the area today and tonight. Despite the expected rainfall totals,
the duration of the event should help mitigate flooding concerns
across the area. However area rivers will need to be monitored in
case they reach bankfull.

The tight pressure gradient will bring blustery conditions to the
area today, as wind gusts approach 30 mph across central and
east-central Wisconsin. Given the area will be on the north side
of this system, some colder air wrapping in from the north will
bring the possibility of snow mixing in at times today and
tonight, particularly across north-central Wisconsin. Despite the
possibility of snow, the main precipitation type is expected to be
rain. In addition the relatively warm, wet ground should help to
mitigate any snow that fell from this system across the northern

High pressure and drier air advecting in from the west will bring
dry conditions back to the are by Thursday afternoon. However
clouds will remain across the area as cyclonic flow remains at mid

.LONG TERM...Thursday Night Through Tuesday
Issued at 332 AM CDT Wed Oct 26 2016

The latest GFS ensemble mean continues to show flattened upper
ridging across the center of the conus through early next week.
Models continue to indicate that shortwaves will eject out of the
large-scale trough off the west coast, and provide occasional precip
chances.  However, significant differences remain with the sensible
weather starting on Friday, making this a low confidence forecast.
Will put more weight into the nam/sref through 12z Sat before
shifting towards the gfs.

Thursday night through Friday night...High pressure will be sliding
from the western Great Lakes at the start of the Thu evening to the
eastern Great Lakes by Friday morning.  Warm advection will
strengthen in response, with clouds increasing aloft, but some
indications that low clouds never really depart over central and
north-central WI.  Will keep sky conditions mostly cloudy here and
partly cloudy elsewhere.  Low pressure will move into northern Lake
Superior region during the afternoon with warm air ahead of the
system continuing to invade the region.  Models have backed off of
precip chances over far northern and northeast WI, mainly due to the
abundance of mid-level dry air.  Will back off precip chances some.
Colder air will return behind the low for Friday night...with a
chance of light showers across far northern WI developing.

Rest of the forecast...Northwesterly flow could continue to generate
showers in the lake effect belt of n-c WI on Saturday.  But will be
watching the next shortwave traverse the region on Saturday and
Saturday night.  If the group of models which include the
nam/gfs/gem/sref are correct, this shortwave will mainly produce
precip over central and southern WI.  Confidence is low, due to the
more robust ecmwf, which shows widespread rain for these periods.
After a dry Sunday, the next system will be moving towards the
region on Monday into early Tuesday.  In general though, precip
amounts look to be light with each system.

.AVIATION...for 12Z TAF Issuance
Issued at 626 AM CDT Wed Oct 26 2016

A low pressure system will track through northern Illinois today
and this evening. Conditions are expected to continue to
deteriorate from west to east this morning, with widespread
IFR/LIFR cigs and IFR/MVFR vsbys due to rain today. Increasing
winds in the boundary level will create gusty surface winds along
with a period of LLWS conditions this morning. The rain is
expected to taper off from west to east later tonight as the low
pressure system departs to the east.



SHORT TERM.....Kurimski
AVIATION.......Kurimski is the U.S. government's official web portal to all federal, state and local government web resources and services.