Area Forecast Discussion
Issued by NWS Green Bay, WI
FXUS63 KGRB 110102 AAA
Area Forecast Discussion...UPDATED
National Weather Service Green Bay WI
702 PM CST Tue Jan 10 2017
New Information added to update section
Issued at 701 PM CST Tue Jan 10 2017
Snow has tapered off early this evening, but areas of blowing
snow are occurring across much of central, north central and far
northeast WI. Weather not meeting criteria for a warning, as vsbys
in blowing snow are generally 2-5 miles, but roads are treacherous,
especially in north central WI, where the WDOT has advised motorists
to stay off the roads. Think a good compromise right now is to
convert the winter storm warning to a winter weather advisory for
blowing snow, and mention the terrible road conditions in the
Will cancel the winter weather advisory for Waushara, as it
rained for much of the day, so blowing snow is not much of a
concern. Will add them into the wind advisory though, as they
recently gusted to 43 knots.
.SHORT TERM...Tonight and Wednesday
Issued at 337 PM CST Tue Jan 10 2017
There seem to be too many concerns in the short term to pick just
one or two.
Heavy snow was falling this afternoon to the left of an
intensifying surface low pressure system that was passing through
Wisconsin. Some locations in central and north central Wisconsin
reported snowfall rates in the 1 to 2 inch per hour range during
the afternoon. Warm air in east central Wisconsin changed
precipitation to mostly rain for a good chunk of the day. There
was at least isolated thunder in east central Wisconsin to add to
the already active situation. Strong west-northwest winds are
expected in the tight surface pressure gradient in the wake of
the departing low. This may cause some issues with blowing and
drifting snow, especially north and west of the Fox Valley. This
was a major reason for extending winter weather headlines. Winds
in the Fox Valley and Lakeshore areas should be strong enough to
at least reach the low end of wind advisory criteria during the
late afternoon and evening.
The arrival of much colder air will cause any falling rain to
change to snow, and rain that was already on the ground to rapidly
freeze. Precipitation should end during the early evening as the
system quickly departs. Winds are expected to weaken by around
midnight, winter weather and wind headlines, over the land, should
all be gone after that. Clouds and winds will keep overnight lows
from getting colder than the single digits and teens.
There is only a brief respite before snow chances and amounts
enter the picture again. Upper jet dynamics, along with a mid
level trough, will bring a chance for snow to the area starting
Wednesday morning, with snow likely across the north by midday.
12Z model snow amounts differed, and they were not even in total
agreement whether the entire area will get measurable snow. Have
opted to confine the likely pops to the northwest half of the
forecast area, which generally matches the forecast grids from
surrounding offices. HPC guidance suggest that headlines may be
needed for this upcoming event as well.
.LONG TERM...Wednesday Night Through Tuesday
Issued at 337 PM CST Tue Jan 10 2017
There is a big difference to start this forecast period
Wednesday night, depending on which model solution is most correct.
The NAM has been consistent in showing a wave moving northeast
along the surface front across northern Illinois to southern lower
Michigan with a coupled jet structure moving across central and
east central Wisconsin with strong mid level convergence producing
a few more inches of snow. The GFS suggests this as well but to a
lesser degree, while the ECMWF just has some light snow across northern
Wisconsin associated with the right entrance region of the jet. The
NAM seems to have done a better job with this past system so will
side with it for now. After this goes by there could be some light
snow across the southeast quarter of the forecast area early Thursday
as some jet energy moves through. Then dry and colder Thursday afternoon
through Saturday with temperatures 5 to 15 degrees below normal.
Fresh snow will make nights especially cold.
Milder weather looks likely next week as the upper flow becomes
nearly zonal. There could be significant snow or mixed precipitation
at times as some fairly significant upper systems arrive from the
Pacific and move across the Rockies into the Plains states. Highs
should be 5 to 10 degrees above normal.
.AVIATION...for 00Z TAF Issuance
Issued at 541 PM CST Tue Jan 10 2017
Snow will quickly end early this evening, but strong west winds
will produce some blowing and drifting snow in open areas of
central, north central and far northeast WI. West winds will
gust to over 30 kts in most areas this evening, with gusts as
high as 40 kts in the Fox Valley and Lakeshore areas. Toward
midnight, winds should diminish, with flight conditions briefly
returning to VFR at the TAF sites.
Another round of snow is expected to develop over parts of central
and north central WI early Wednesday morning, and spread southeast
across the rest of the forecast area by midday. Conditions should
quickly drop to IFR once the steadier snow develops. Improving
visibilities will arrive in north central WI as the snow tapers
off there in the afternoon.
Wind Advisory until midnight CST tonight for WIZ022-038>040-045-
Winter Weather Advisory until 10 PM CST this evening for WIZ005-