Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 241135

Area Forecast Discussion
National Weather Service Green Bay WI
635 AM CDT Sat Mar 24 2018

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Sunday
Issued at 338 AM CDT Sat Mar 24 2018

High clouds have thickened over the forecast area, in association
with the system that was producing a swath of heavy snow well to
our southwest. These clouds will erode from northeast to southwest
during the day as another surge of very dry air arrives from the
Hudson Bay high. This dry air surge is expected to be very
impressive, resulting in 850 mb dew point depressions increasing
to 30-50 C tonight into Sunday.

Gusty east to northeast winds are anticipated today, as the
pressure gradient strengthens between the Hudson Bay high and
low pressure tracking through the Upper Midwest. Minor CAA will
result in temperatures a couple degrees cooler than yesterday.
Winds will turn southeast on Sunday, leading to a modest warmup,
with highs in the 40s away from Lake Michigan.

Daytime mixing should lower dew points into the single digits
again over parts of north central and northeast WI this afternoon.
On Sunday, mixing should tap into the previously-mentioned very
dry air aloft, leading to widespread low dew points, some as low
as zero in north central WI. This will lead to very low relative
humidity in the 15 to 25 percent range in the sandy soil regions.
The combination of low humidity and gusty southeast winds will
result in elevated fire weather conditions, especially in the
grassy areas of central and east central WI, where there is little
or no snow cover.

.LONG TERM...Sunday Night Through Friday
Issued at 338 AM CDT Sat Mar 24 2018

The mid level ridge and Canadian high pressure, that will keep
the weekend dry, are forecast to move east. Warmer but wetter
weather is in store early in the work week. Low level moisture
will increase ahead of an approaching surface system that will
combine with a mid level short wave to bring rain to the forecast
area. Onset of rain chances looks to be Monday afternoon in parts
of central Wisconsin and there is a slight chance a little farther
to the east. Boundary layer temperatures should be warm enough to
keep precipitation in liquid form as it spreads across the rest
of the area Monday night. There may even be some thunder in parts
of east central Wisconsin late Monday night and Tuesday. Rain
chances decrease from west to east Tuesday and Tuesday evening as
the short wave and surface system depart. There could be a short
period of snow or mixed rain and snow in parts of northern and
central Wisconsin Tuesday evening before the precipitation ends.
Surface high pressure moving into the region is expected to keep
Wednesday and Wednesday night dry. The 00Z models had QPF across
parts of northern Wisconsin at times Thursday through Friday.
There were some location and timing differences so PoPs are low
end chance category or slight chance. Will need to watch closely
and see how things develop since cold cyclonic flow on the back
side of a surface low, behind a passing cold front, combined with
a passing mid level trough could produce significant lake effect
snow showers. Confidence is low regarding snow showers due to
model differences.

Expect warmer conditions for much of the work week, with highs
mostly in the 40s to lower 50s. Colder air moves in behind a
passing cold front, bringing below normal temperatures back to the
area for Friday.

.AVIATION...for 12Z TAF Issuance
Issued at 629 AM CDT Sat Mar 24 2018

The main aviation concern will be increasing east to northeast
winds, which will be gusty at times, especially in central and
east-central Wisconsin during the late morning and afternoon.
High clouds will erode from northeast to southwest during the
afternoon and early evening.

Added a brief period of LLWS at AUW/CWA early this morning, due
to east-southeast flow of 35 knots just above the surface.



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