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Area forecast discussion
National Weather Service Green Bay WI
255 PM CDT Tue Mar 28 2017

Forecast discussion for routine afternoon forecast issuance

Short term...tonight and Wednesday
issued at 255 PM CDT Tue Mar 28 2017

The latest rap analysis and satellite/radar imagery show high
pressure stretching from central Canada to the western Great Lakes
early this afternoon. Skies are mostly clear across the region,
except near the lake and Bay where low stratus has remained solid so
far today. But over the past hour, the stratus has been starting to
break up over the Door Peninsula. This trend should continue for
the rest of the afternoon with further day time heating. Looking to
the west, clouds are spreading northeast over the northern plains
and into the northern Mississippi Valley. Forecast concerns include
cloud trends, and potential for fog tonight.

Tonight...Canadian high pressure will continue to build southward
into the region. Despite the loss of heating, think the low stratus
deck will continue to erode over Lake Michigan, but not quickly
enough to prevent a mostly cloudy start to the evening along the
Lakeshore. Some concern that this cloud mass could surge southwest
and lower late tonight into the Fox Valley and Lakeshore, but
confidence is low for that occurring, so will show clearing skies
overnight. Otherwise, will see mid and high clouds invade the region
from the west late. With clear skies and light winds, some ground
fog could also reform over north-central WI and eastern WI late.
Lows ranging from the mid 20s in the north to the low 30s near the

Wednesday...clouds will continue to thicken and lower through the
day as low pressure moves across the Central Plains. Light precip
will try to move to central WI by late in the afternoon, but think
the east winds out of the Canadian high will hold it off. Temps
will continue to be cooler over eastern WI due to the clouds/east
wind combo. Highs ranging from near 40 near the lake to the upper
40s over central WI.

Long term...Wednesday night through Tuesday
issued at 255 PM CDT Tue Mar 28 2017

Main concern for this period will be the system moving across the
region Wednesday night and Thursday, and then another system early
next week.

The system for Wednesday night and Thursday is a little more
potent on the European model (ecmwf) compared to yesterday. This could lead to
a few inches of snow late Wednesday night into Thursday morning
across the southern two-thirds of the forecast area. Highest snow
and precipitation totals will be south of a Marinette to Wausau
line. Per coordination with National Weather Service Milwaukee, bumped up snow totals
across our southern tier of counties. If latest European model (ecmwf) is correct,
snow totals may need to be bumped up a little more over the next
day. The snow could make for some hazardous travel for the
Thursday morning commute to work or school. Any lingering rain
should exit east-central and northeast Wisconsin Thursday evening.
High pressure will dominate the weather pattern on Friday and
Friday night.

A weak cold front could bring a chance of rain/snow showers
Saturday afternoon and Saturday night across the north. System
passing to the south could bring a chance of precipitation Sunday
night into Monday, but the next round of significant precipitation
will be Monday night into Tuesday. Temperatures will be close
to normal through Friday, with slightly above normal temperatures
for the weekend.

Aviation...for 18z taf issuance
issued at 1155 am CDT Tue Mar 28 2017

VFR conditions expected at most locations through the taf period,
but with a couple exceptions. IFR/LIFR conditions will impact the
Lakeshore areas through mid-afternoon, where very low stratus and
pockets of dense fog are moving southwest off the lake. Some
concern that fog could reform along the Lakeshore again late
tonight, but confidence is too low to include in the tafs. Fog
could also redevelop over north-central WI late tonight, but
again, confidence is low. Otherwise, mid and high clouds will
increase late tonight into Wednesday morning.

Grb watches/warnings/advisories...

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