Area Forecast Discussion
Issued by NWS Green Bay, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
000
FXUS63 KGRB 111804
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1204 PM CST Wed Jan 11 2017

New Information added to update section

.UPDATE...
Issued at 1204 PM CST Wed Jan 11 2017

Will remove Southern Marinette and the rest of Oconto from the
advisory but will let the rest of the Advisory run its course
through 3 pm. Area radars shows the back edge of the snow working
over west central Wisconsin late this morning. A narrow band of
heavy snow around 6 inches appears ongoing from around Squirrel
Lake area in Western Oneida to Woodruff to the Eagle River area. 4
to 5 inches reported in this region late this morning.

UPDATE
Issued at 958 AM CST Wed Jan 11 2017

Current Weather Advisory overlaid with ongoing radar trends
appear to be well on target. Perhaps only southern Marinette may
not get the advisory snow but central Marinette county may get
clipped. Quick calls and vsbys indicating inch per hour snow
falling. Would not be surprised to see a narrow 6 inch amount
surrounded by the widespread 2 to 4 inch amount with these combo
jetlet and fgen structures. Will add a local higher amount in the
advisory area to account for this.

For later afternoon and evening, HRRR indicating a near advisory
snow for part of east central Wisconsin toward the lakeshore with
the next system passing to the southeast of the area. Will focus
on this later today as this pcpn and possibly mixed may impact
the evening commute.
&&

.SYNOPSIS...
Issued at 448 AM CST Wed Jan 11 2017

Some light snow today into tonight, followed by a brief shot of
arctic air for the latter part of the week. January thaw-like
conditions expected next week.

A persistent block over the northeast Pacific combined with energy
undercutting the block were maintaining a strong baroclinic zone
downstream over the central and eastern CONUS. The block is
forecast to finally break down late this week, with the positive
upper height anomaly from the block migrating westward to
northeast Asia. That will allow a strong, broad, low-amplitude
Pacific jet to expand eastward across southern Canada and the
CONUS by next week.

Disturbances riding along the baroclinic zone currently draped
over the area will bring a few more rounds of snow through the
first part of the weekend. A final round of precipitation is
possible late in the weekend, but precipitation type becomes
highly uncertain by then as much of the cold air will have
released back off to the northeast. Total precipitation amounts
for the period are likely to end up above normal.

Temperatures during the early to middle part of the forecast
period will respond to north and south shifts in the baroclinic
zone as individual weather systems cross the region. A prolonged
period of above normal temperatures will likely begin next week
when the low-amplitude westerly flow off the Pacific dominates
NOAM.
&&

.SHORT TERM...Today...Tonight...and Thursday
Issued at 448 AM CST Wed Jan 11 2017

Another complicated forecast this morning. A lead band of snow
showers was surging quickly across the area. The southern portion
should weaken, but the precipitation across the north is likely to
persist, and could become quite banded as strong mid-level
frontogenetic forcing slides into that area. Started the forecast
with a general 3 inch snowfall across the north, though some
locations could get double that if a small-scale band persists or
redevelops over the same locations. Later shifts will need to
monitor and adjust amounts accordingly. Posted a Winter Weather
Advisory for the north due to the snow.

Opted to keep Door county out of the advisory initially.
Precipitation will take a little longer to get to that area.
Also, although snowfall amounts in the current forecast are
similar to areas farther west, (especially over the northern tip
of the county), confidence in the location of the best snows
decreases farther east. Door can be added to the advisory later
this morning once radar trends make it clearer where the best
snows will occur.

As the first band of precipitation weakens and begins to shift out
of the area this afternoon, a second band is forecast to develop
over southwest Wisconsin and slide northeast. Raised PoPs and
snowfalls in east-central Wisconsin for the afternoon and early
evening to account for this. Some sleet or even freezing rain
could be mixed with the snow from OSH-MTW south. Amounts for this
area are generally sub-advisory in the current forecast. But as
mentioned earlier, these small scale snow bands are hard to
diagnose more than a few hours in advance. The snowfall forecast
for east-central Wisconsin will need to be monitored closely. If
it becomes apparent amounts will be higher than now forecast, or
if it begins to look like a burst of snow will occur during the
afternoon commute, an advisory might still be needed.

Some of the models indicate a third band of snow could affect the
southeast part of the area overnight, though support for that was
more marginal than for the first 2 events. Covered with chance
PoPs in the forecast for now.

Quieter weather should return Thursday, though with the baroclinic
zone still draped across the area it`s certainly not inconceivable
that another snow band could develop.

.LONG TERM...Thursday Night Through Tuesday
Issued at 333 AM CST Wed Jan 11 2017

Main focus for this period will be the bitterly cold temperatures
Thursday night into Friday morning, then a moderation in temperatures
this weekend with above normal temperatures expected early next
week. In addition, a system will affect the area bringing another
round of mixed precipitation.

For Thursday night into Friday morning, bitterly cold temperatures
are in the forecast with lows in the single digits below zero east
and in the teens below zero west. A northwest wind of 5 to 10 mph
will produce wind chill readings of 20 below to 30 below zero
north and west of the Fox Valley. A wind chill advisory is
anticipated for this area late Thursday night and Friday morning.
Another cold day is expected on Friday with highs from 5 above to
12 above zero. Minimum temperatures tricky Friday night as a weak
upper level disturbance passes to the south of the area. This
feature will bring an increase in cloudiness and a chance of light
snow mainly south of highway 29. Minimum temperatures across the
far north will need to be monitored as they may need to be lowered
depending on how thick cloud cover is in this region.

A gradual moderation in temperatures is expected this weekend with
above normal temperatures expected for the first half of next
week. The next weather maker will bring a wintry mix to the region
Monday into Tuesday. Some differences noted between the Canadian
and ECMWF with the amount of warm air spreading northward into the
region. Will also need to contend with pavement temperatures which
may be slower to respond due to the expected cold weather late
this week. Later shifts will be able to sort out the details.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1027 AM CST Wed Jan 11 2017

Bands of moderate snow will continue to produce
periods of IFR conditions across northern Wisconsin through mid
afternoon before diminishing later afternoon and evening. As
northern Wisconsin snow tapers off, another region of snow,
possibly mixed with sleet will produce lower end MVFR or IFR
conditions across east central Wisconsin this afternoon and
evening. Conditions to gradually improve from north to south from
tonight into Thursday as high pressure nudges into northwest
Wisconsin.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 3 PM CST this afternoon for WIZ005-
010>013-018-019.
&&

$$

UPDATE.........TDH
SYNOPSIS.......Skowronski
SHORT TERM.....Skowronski
LONG TERM......Eckberg
AVIATION.......TDH



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.