Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 212231

Area Forecast Discussion
National Weather Service Green Bay WI
531 PM CDT FRI OCT 21 2016

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Saturday
Issued at 247 PM CDT Fri Oct 21 2016

The latest RAP analysis and satellite/radar imagery show a surface
ridge axis extending from north-central Ontario, across central WI
to central Texas early this afternoon. But despite the close
proximity of the surface high, a cold airmass and steep low level
lapse rates continues to lead to widespread low clouds, similar to
yesterday.  Think this cloud cover will persist through the rest of
the afternoon, and likely into much of the evening over eastern WI.
Not out of the question that a spotty shower could occur over
Marinette and Door counties. Looking upstream, broken mid and high
clouds are pushing east over the northern Mississippi Valley in a
region of warm advection. A few weak returns are showing up over
eastern North Dakota and northern Minnesota.  Forecast concerns
revolve around light precip chances and cloud trends.

Tonight...High pressure at the surface will be moving across the
region tonight.  The high is not exactly clean however, so will keep
scattered wording over north-central WI into the evening. Otherwise,
think the broken cloud cover will persist over eastern WI through
much of the evening and possibly overnight over the Door. Deep upper
troughing will finally depart the area overnight, and the resultant
warm advection will bring a swath of broken mid and high clouds
across the area. The saturated layer is not really deep, so at best
think only a few sprinkles will be possible.  Confidence is too low
for an inclusion of sprinkles into the forecast though, and will
leave the area dry instead.  Lows mainly ranging from the mid 20s to
mid 30s.

Saturday...A layer of 5-6 kft clouds will shift east across the
region through the morning and into early afternoon with warm
advection lowering.  The atmosphere becomes really dry above this
layer, so precip chances will be too small to mention.  As the
clouds depart in the afternoon, should see the sun return along
with warmer temps.  Highs in the mid to upper 50s.

.LONG TERM...Saturday Night Through Friday
Issued at 247 PM CDT Fri Oct 21 2016

Northwest flow will prevail into early next week, with generally
dry quiet weather expected. The main exception will be Sunday when
a mid level disturbance tracking through the northern Great Lakes
brings the chance for showers across the extreme northern cwa. The
next significant chance for widespread rain arrives during the
middle of next week as a low pressure system develops across the
central plains on Tuesday. This low will track to the south of the
area on Wednesday and Wednesday night, bringing rain to much of
the area. Being on the cold side of the system there could be a
few snowflakes mixed in with the rain at times Monday night and
Tuesday night across north-central Wisconsin, however the impact
is expected to be minimal. Although the low will be east of the
area late next week, additional shortwaves embedded in northwest
flow will bring a small chance for showers during this period.

.AVIATION...for 00Z TAF Issuance
Issued at 429 PM CDT Fri Oct 21 2016

As high pressure drifts slowly east tonight, a weak frontal
system will approach from the Northern Plains. A lower end VFR
clouds will linger over eastern Wisconsin tonight while mid to
high level clouds approach from the west. Little change in cloud
expected for saturday, with perhaps the higher end VFR clouds
become more dominate.




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