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Area forecast discussion 
National Weather Service Green Bay WI
251 PM CST Tuesday Nov 25 2014

Forecast discussion for routine afternoon forecast issuance

Short term...tonight and Wednesday
issued at 251 PM CST Tuesday Nov 25 2014

Cloud trends will be the key to the min temperature forecast for tonight.
Unfortunately...cloud forecast for early tonight is tricky. Low clouds have
been slower to exit the area than initially expected. But they
have become somewhat cellular looking on satellite imagery...indicating
they may dissipate during the evening. But another batch of
low/middle clouds is heading eastward from east-c Minnesota...and looks like it will pass
across at least the western/northwestern part of the forecast area early tonight. A
much larger area of high/middle clouds will overspread the area from the
plains later in the night. So with a fresh deep snowcover and light
winds...min temperatures pretty much come down to whether or not there
are any clear periods during the evening. Looks like the east/NE part
of the area will have the best chance for a period of clear skies during
the evening. Went with lowest temperatures there...though always have to
be concerned that north-c WI could just free-fall with even a short
break in the clouds there. Looks like they will be clear right after
sunset...so took temperatures down hard there at dusk...then let them
come back during the night as clouds increase.

The other main forecast issue is the chance for snow. Still a few
flurries across the area...so will linger those into the evening.
Radar returns from eastern Minnesota/western WI also suggest flurries still
occurring with the area of low clouds heading in from the west. The
consensus of the models was to keep the main area of snow with the
approaching system SW of the area tomorrow. But the large area of
radar echos moving east-southeastward across ND on the radar mosaic has certainly
caught my attention. Delayed the onset of precipitation as that area of
precipitation should turn more southeast as the upper flow amplifies...but that will
need to be watched. Also added chance of flurries to far eastern WI
tomorrow as low-level winds could turn onshore as surface low heads
toward Iowa.

Long term...Wednesday night through Tuesday
issued at 251 PM CST Tuesday Nov 25 2014

Light snow and lake-effect potential Wednesday night into Thursday...and
precipitation trends and type with a Pacific low pressure system late
Thursday night through Sat night...are the main forecast concerns.

An upper trough and low level cyclonic north flow will affect the region
Wednesday night...bringing around an inch of snow to much of the
region. Have been concerned about lake-effect potential for Vilas
County the past couple days...but it now appears that wind
trajectories will be north-northeast when the synoptic enhancement
occurs Wednesday evg...and some low level shear may also inhibit the
development of snow bands until late in the event. Best snowfall
should stay west and north of Vilas County...so will only carry 1
to 3 inch accums for now. The snow will taper off late Wednesday night
into early Thursday...though les should continue through at least
midday Thursday in Vilas County.

The flow pattern will turn zonal for the end of the work week
and much of the weekend. Strong warm air advection will develop late Thursday night/
Friday as high pressure departs to the east and a Pacific low
pressure system organizes in the northern plains. A swath of
1 to 3 inches of snow is expected to occur with the warm air advection...
then lift out of northeast WI Friday afternoon. Dry slotting and
warming aloft may result in some patchy mixed precipitation Friday night into
Sat night...before the Pacific low passes and cold air floods back
into the region. Confidence in the details during this period are
low.

After the brief warmup into the 30s on Saturday...temperatures
will plummet on Sunday into Monday...before rebounding again on
Tuesday.
&&

Aviation...for 18z taf issuance
issued at 1132 am CST Tuesday Nov 25 2014

As typical of this time of year...figuring out low cloud trends is
a challenge. Though thinning...clouds with MVFR ceilings remained across
the bulk of the area at mid-day. They should continue to thin and
shift off to the east...but weak keep MVFR ceilings and some flurries going
well into the afternoon. Another patch of low clouds from the west will probably
make it into at least western taf sites before shiftg off to the NE
with backing low-level flow.

The other aviation concern is the potential for visibilities to drop off
during the night due to fog as low-level inversion begins to
strengthen across the area. This was hinted at in both the met and
lav guidance...so added to the tafs.
&&

Grb watches/warnings/advisories...
none.
&&

$$

Short term.....Skowronski
long term......kieckbusch
aviation.......skowronski

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