Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kgrb 241754 

Area forecast discussion
National Weather Service Green Bay WI
1154 am CST Tue Jan 24 2017

Updated aviation portion for 18z taf issuance

Short Wednesday
issued at 326 am CST Tue Jan 24 2017

The main forecast concern is headlines and snowfall amounts with
the incoming low pressure system tonight into Wednesday.

A weak ridge of high pressure was edging eastward into WI early
this morning. Widespread low clouds remained over the region, but
fog was not as widespread as it has been over the past week. That
being said, there were still some patches of thicker fog, mainly
over Door County and portions of north central WI. Since there
have been observations of at least locally dense fog over Door
County early this morning, have decided to let the dense fog
advisory continue there.

Expect generally quiet weather today, as the weak ridge of high
pressure moves through. Guidance suggests continued improvement
in the foggy conditions by afternoon, so will follow that trend.
With the Nor'easter heading up the East Coast and having a
blocking influence on upstream systems, it's not surprising that
models continue to delay the precipitation arrival with the low
pressure system approaching from the Central Plains. Have pulled
the small pops from our far southwest counties late in the day.

Tonight, expect light pcpn to arrive in central and east central
WI by mid-evening or so. At onset, it appears that pcpn type will
be drizzle/freezing drizzle, as moisture is quite shallow, and
there is little or no ice in the saturated layer. Light icing may
occur on the northern periphery of the pcpn shield. Snow will
develop and increase in intensity in central WI and the southern
Fox Valley overnight, as stronger forcing and deeper saturation

The best snows will occur across central and east central WI late
tonight into Wednesday morning, as the surface and upper lows
arrive. Though some accumulation may continue into Wednesday
afternoon, warming temperatures should result in a rain/snow mix
in some areas. With expected snowfall of 3 to 6 inches occurring
south of a line from Wausau to Shawano to Green Bay and Kewaunee,
have decided to issue a Winter Weather Advisory. Timing will be
from 9 PM tonight through 6 PM Wednesday.

Long term...Wednesday night through Monday
issued at 326 am CST Tue Jan 24 2017

The surface and mid level systems, responsible for the snow in
the short term part of the forecast, will be passing southeast of
the forecast area by 06z Thursday. This is expected to result in
about another inch of accumulation across that part of the
forecast area mainly from the Fox Valley east to Lake Michigan on
Wednesday night. Drier air in the dendritic growth zone will
cause precipitation type to be messy at times, with a chance for
a wintry mix also present.

A cyclonic circulation of colder air on the back side of the
departing system will keep at least a chance for snow showers
going across north central Wisconsin until the end of the
weekend/early next week when surface high pressure moves into the
region as a mid level trough approaches. This will cause winds
to take on too much of a westerly component for lake effect in
northern Wisconsin.

Temperatures drop off behind the departing system but it will not be
exceptionally cold, with highs near normal, and low temperatures
mostly above normal.

Aviation...for 18z taf issuance
issued at 1149 am CST Tue Jan 24 2017

Low clouds (mvfr) are expected to linger across the region, although
a few breaks in the clouds (vfr) are possible through late afternoon.
For tonight, low clouds will continue with some drizzle developing
later this evening across much of the area. Snow should arrive
around 06z at kisw/kmfi/ky50/kosh. The snow should arrive around
08z for kauw/kcwa/kgrb/kmtw/katw. Snow will continue through much
of the remainder of the night into Wednesday evening, before
tapering off to drizzle or ending.


Grb watches/warnings/advisories...
Winter Weather Advisory from midnight tonight to 6 PM CST
Wednesday for wiz035-036-045-048.

Winter Weather Advisory from 2 am to 6 PM CST Wednesday for

National Weather Service Glossary of Abbreviations