Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Green Bay WI
309 PM CST Thursday Nov 26 2015
Forecast discussion for routine afternoon forecast issuance
Short term...tonight and Friday
issued at 309 PM CST Thursday Nov 26 2015
Precipitation trends/type and winter weather headlines are the main forecast
Widespread rain was occurring over the forecast area this afternoon...
except over Vilas...Oneida and northern Forest counties...where
snow was falling. Spotter reports in SW Oneida County indicated
that big flakes were falling and starting to accumulate on the
roads...and several web cams indicated around a half inch of
fresh snow on the ground in Vilas County.
Have utilized the 12z GFS/00z European model (ecmwf) to time the precipitation changeover
to snow...which has just reached Rhinelander...should reach Wausau
around 6 PM...and Green Bay close to midnight. Have not received
any sleet reports yet...but think we will get some for a few
hours at any given location as the precipitation changeover commences.
Latest quantitative precipitation forecast/snowfall forecasts suggest totals of 2 to 3 inches NC/far
NE WI...1 to 2 inches in c/NE WI...and less than an inch in the
Fox Valley/Lakeshore areas. Precipitation is expected to taper off earlier
than previously thought (mid to late evg) over our northwest counties...
and a decrease in middle-level moisture may lead to a few hours of
fzdz before the precipitation completely ends. Will keep all of the
advisories going...even though snow and sleet amounts may stay
below criteria. Hazardous travel is still expected...as wet roads
freeze this evg...and this will cause problems for Thanksgiving
day travelers and black Friday shoppers. Sports enthusiasts in
Green Bay will encounter a very wet evening...with mixed precipitation
developing during the late evening. The evening shift can cancel
the advisories early if poor travel conditions do not materialize
Aside from some lingering lake effect snow showers in Vilas
County...and a few flurries near mtw...Friday should be dry.
Expect some decrease in clouds during the afternoon.
Long term...Friday night through Thursday
issued at 309 PM CST Thursday Nov 26 2015
A system that is forecast to impact the area for the early to
middle part of next week is the main concern for the long term.
Drier weather is expected Friday night as surface high pressure
builds into the area from the west and 500mb flow becomes
confluent over the region. Kept Friday night lows pretty much the
way they were. They seemed reasonable based on expected clear
skies...light/calm wind and fresh snow-cover.
A 500mb cyclone over the western Continental U.S. Will move east over the
weekend into early next week. Models are more consistent with
timing of precipitation arrival ahead of this system and appear to
be zeroing in on Monday night. Precipitation type is a bit
uncertain at this point...but there could be some snow
accumulation as it looks like most of the area will be cold
enough for snow Monday night. Daytime temperatures on Tuesday
should change precipitation to rain and/or snow across all but
central and north central Wisconsin. The 12z Canadian brought a
dry slot into the state on Tuesday...shutting down most of the
precipitation in the area by Tuesday afternoon. The 12z European model (ecmwf) and
12z GFS both had quantitative precipitation forecast across the entire state through 00z
Wednesday but the ec cut it off at the WI/Illinois border. Not great
confidence in the precipitation forecast with the system due to
the differences among the models. The main upper level system
should be departing late Tuesday night/early Wednesday. Have
mostly slight chance probability of precipitation for Tuesday night...a small area of
slight chance probability of precipitation on Wednesday then dry through the end of the
Highs are expected to be near...or a few degrees above...normal.
Aviation...for 18z taf issuance
issued at 1050 am CST Thursday Nov 26 2015
Ceilings and visibilities will remain in the IFR/LIFR categories
this afternoon and evening...as widespread precipitation covers the area.
Rain or mixed precipitation will gradually change to snow from northwest to southeast...
with the changeover occurring middle-afternoon at rhi...early evg
at auw/cwa...and midnight or a little later at grb/atw. Gusty
north winds will develop early this evg...especially in the Fox Valley/
lkshr areas. As drier air arrives and precipitation decreases tonight...
flight conditions should improve to MVFR.
Winter Weather Advisory until 2 am CST Friday for wiz013-020-021-
Winter Weather Advisory until 2 am CST Friday for wiz005-010>012-