NWS-Green Bay Forecast Discussion

 

						FXUS63 KGRB 091735
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1135 AM CST Sun Dec 9 2018

Updated aviation portion for 18Z TAF issuance

.SHORT TERM...Today...Tonight...and Monday
Issued at 238 AM CST Sun Dec 9 2018

Clouds continue to plague the area early this morning, which is
causing a disparity in temperatures across the region. Across
areas that are clear temperatures are about 10 to 15 degrees, with
temperatures around 20 across areas that have remained cloudy.
Models continue to clear out clouds later this morning once the
sun rises. High pressure will keep the weather dry today, as high
temperatures rise into the middle to upper 20s.

Overnight things get a bit tricky again as some models develop
clouds once again while others keep skies clear. Given the
propensity to develop clouds the last few nights will place clouds
in across central and north-central Wisconsin. Overnight lows
will generally range from 10 to 15 across central and north-
central Wisconsin before clouds cause temperatures to stall or
rise, with lows in the middle to upper teens across east-central
Wisconsin.

A weak low pressure system will pass to the north on Monday,
however dry weather is expected to remain across the region as
moisture and lift are not that impressive with this system. Highs
on Monday will generally remain in the middle to upper 20s.

.LONG TERM...Monday Night Through Saturday
Issued at 238 AM CST Sun Dec 9 2018

Forecast concerns mainly revolve around precip chances from
Wednesday through the end of this period.  Models have come into
better agreement during this time period, so will continue to use a
blend of the ecmwf and gfs.

Monday night through Tuesday night...Shortwave energy will be
passing over the northern Great Lakes on Monday night and possibly
on Tuesday as well.  Best combination of forcing and moisture from
these shortwaves remains expected to pass well north of the region,
so no precip is expected.  But will probably see scattered to broken
high clouds push overhead on Monday night, and also possibly some
low stratus push into far northeast WI on Tuesday afternoon and
evening.  No significant changes to temps.

Rest of the forecast...A fast moving Pacific system will then
proceed to cross the region on Wednesday afternoon and Wednesday
night.  With a southeast wind ahead of the system, temps could
become warm enough for precip to mix with or change to rain over
northeast WI.  It appears that areas further west could see an inch,
maybe two if deeper moisture is quicker to move northeast than
models advertise.  Models are then trending further south with a
southern stream system late in the work week.  This may cause
shortwave energy to split the region to the north and south if
trends continue.  But for now, the back edge of the precip shield
may graze east-central WI on Friday.  High pressure then moves in to
start next weekend.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1118 AM CST Sun Dec 9 2018

MVFR/IFR CIGS across central into east-central Wisconsin should
erode away as the afternoon progresses. The main question for
tonight is will the low clouds and stratus redevelop. All the
numerical guidance suggests no, but there is weak warm advection
in the low levels of the atmosphere, combined with the inversion
should allow for areas of low clouds (IFR or lower) to develop
across much of the area tonight, except across far northeast
Wisconsin. Have low clouds and fog arriving around 02-04z
across portions of central and north-central Wisconsin and
05-07z at KGRB/KATW/KMTW. The low clouds and fog should burn
off by mid to late morning on Monday.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....Kurimski
LONG TERM......MPC
AVIATION.......Eckberg