Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 181102

Area Forecast Discussion
National Weather Service Green Bay WI
602 AM CDT Sun Mar 18 2018

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Monday
Issued at 250 AM CDT Sun Mar 18 2018

Surface analysis early this morning shows a ridge of high pressure
extending over minnesota into mid Mississippi valley region.
Meanwhile a low pressure system over Lake Superior will slide
east of the region today. This low pressure system will drag a
cold front over the area this afternoon and evening leading to
cooler temperatures for the start of the new work week along with
more clouds. Temperatures trends will be the primary issue during
this period.

With temperatures rising well above normal this afternoon, this
cold front will be likely be preceded with a back door pneumonia
type cold front dropping southward along the lakeshore today.
Temperatures along the bay and Lakeshore will turn sharply cooler
as winds turn northeast this afternoon.

Even though the cold front will sag into northern Wisconsin this
afternoon, a warm start today will still allow above normal temps
today before cooling late afternoon. Temperatures for Monday will
be about 15 degrees cooler than today/s high readings. Blustery
northeast winds will add to the chill.

.LONG TERM...Monday Night Through Saturday
Issued at 250 AM CDT Sun Mar 18 2018

Medium range models remain in good agreement tonite, and continue to
advertise a quiet pattern through much of the upcoming work week.
With the primary storm track expected to be south of the region,
Hudson Bay high pressure will likely lead to near or below normal
temperatures and below normal precipitation.  A general model blend
will continue to work for this forecast.

Monday night through Tuesday night...Mid and high clouds will be
increasing across the region ahead of various pieces of shortwave
energy moving across the northern Plains.  However, Hudson Bay high
pressure will be positioned over northern Ontario, and funneling dry
air below 700mb into eastern WI.  Therefore think most area will
remain dry, except for possibly the Lake Michigan shoreline where
instability may be just sufficient for a few flurries.  As the
shortwaves move across Wisconsin, progged soundings show that
saturation is looking more robust on Tuesday and Tuesday night.  As
a result, will have a slightly higher chance of flurries or light
snow, particularly over central and north-central WI, and also along
the Lake Michigan shoreline.  Under overcast conditions, temps to
fall back into the 30s.

Rest of the forecast...The shortwave energy will be slowly exiting
the region on Wednesday.  Weak convergent flow, however, will likely
keep broken to overcast conditions in place for much of Wednesday
and possibly into Wednesday night too.  But with mid-level moisture
peeling out, chances for light precipitation will be less than on
Tues/Tues night.  High pressure will return for Thursday, and think
should see more sunshine. Though it appears this sunshine could be
short-lived as models bring in the next chance of widespread precip
in the Fri-Sat period.

.AVIATION...for 12Z TAF Issuance
Issued at 602 AM CDT Sun Mar 18 2018

High pressure over the area will continue the VFR conditions at
the onset today before a cold front approaches from the north late
today. First aviation concern starts this afternoon as a back
door cold front or pneumonia front drops over northeast Wisconsin.
The cold front is expected to begin reaching NC WI around 21z,
but the back door front will race ahead of the surface cold front
and may work over Door county between 18z and 21z and then the taf
sites of GRB, MTW and also ATW between 20z and 23z. Northwest
winds will turn abruptly northeast and may include a few gusts to
20 knots over northeast Wisconsin. The Cold front is expected to
reach central Wisconsin Tafs early this evening. Clouds are
expected to lower to a lower end VFR or MVFR levels during the



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