Area Forecast Discussion
Issued by NWS Green Bay, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 43

000
FXUS63 KGRB 271152
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
652 AM CDT Wed Mar 27 2024

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Snow showers and flurries today into tonight, with up to around
  an inch of snow over northern WI. Below normal temps and
  blustery conditions today as well with gusts to around 30 mph.

- A fast moving shortwave is expected to bring a wintry mix to the
  forecast area Friday night into Saturday. Northern Wisconsin,
  especially along the U.P. border, is most likely to see winter
  weather impacts.

- Another round of active weather is possible early next week,
  although the track and timing for this system is currently
  uncertain. This system has the potential to bring another round
  of wintry precipitation to the area.

&&

.DISCUSSION...
Issued at 336 AM CDT Wed Mar 27 2024

Short Term...Today...Tonight...and Thursday

Snow Chances & Amounts / Cloud Trends:

Cyclonic flow will continue across the western Great Lakes today
as surface low pressure tracks towards Hudson Bay. Flurries and
snow showers remained fairly widespread through the overnight and
early morning hours, especially across northern WI. Within this
flow, a fairly potent shortwave and upper low will move from MN
this morning to central Lake Superior this afternoon. This will
likely continue, then enhance the snow activity later this morning
and afternoon. Best moisture and forcing will be across northern
WI, where up to around an inch of snow is expected. Have increased
snow chances, especially over the north, along with bringing
flurries south across most of the area. If the activity makes it
south of Hwy 29, some rain could mix in during the peak heating of
the day. The snow showers and flurries will slowly end from south
to north this evening/overnight with dry conditions expected on
Thursday as weak high pressure slides into the region.

Have remained on the pessimistic side for clouds today due to the
cyclonic flow/upper system moving through, but some partial
clearing is expected at times, especially over eastern WI. Better
chances for clearing skies arrives late tonight into Thursday as
the system pulls away and drier air works in the from west.

Winds / Wind Chills / Temps:

Pressure gradient will slowly weaken behind the departing low
today, but winds of 30-35 kts around 2000 ft will continue provide
blustery conditions today, with WSW surface gusts between 20-30
mph for most spots. A few gusts to 35 mph are also possible. Gusts
tonight look to be reduced due to the lack of any CAA to aid in
better mixing, but winds of 20-25kt aloft could mix down at times.
West winds of 15-25 mph are expected on Thursday. The winds will
push wind chills into the single digits and teens this morning and
again tonight into Thursday morning.

It will be colder today as CAA pushed 850mb to between -14C & -10C.
Highs should range from the mid and upper 20s across north-central
WI to the mid and upper 30s across eastern WI. Lows tonight will
drop to between 10-20 across central and north-central WI and into
the low to mid 20s in the Fox Valley and lake shore. Temps will
moderate slightly on Thursday with highs climbing into the mid 30s
to mid 40s.

Long Term...Thursday Night Through Tuesday

Focus for the extended remains on weekend and early week systems
that are expected to bring two rounds of wintry precip to the
forecast area. A mix of rain, freezing rain, and snow will be
possible with both systems. However, details are still too few and
far between this far out to ascertain exact amounts or
accumulations.

Weekend precip chances... A shallow and progressive shortwave is
progged to eject from the west coast and up through Wisconsin
Saturday morning as upper-level jet energy builds into the Great
Lakes. A surface low and attendant warm front will thus be placed
across the Wisconsin/Illinois border by Saturday afternoon. While
the warm sector will remain mostly to our south, marginal warm
air advection out ahead of the front will likely result in light
precip beginning to spread north across Wisconsin Saturday
morning. Main concern with this system will be precip type,
specifically potential for freezing rain and minor ice
accumulations across the north as surface temperatures fall below
freezing. There is still uncertainty about how warm the 900 to 800
mb nose gets, with the latest GFS guidance trending the thermal
profile several degrees colder, thus favoring snow as the
dominant precip type instead of freezing rain. However, any
fluctuation of a degree or two would likely paint a different
picture. Ensembles seem to be honing in on central/east-central
Wisconsin for highest QPF amounts averaging at around 0.25 to
0.3". Suspect that QPF may trend on the higher end of what
ensembles are hinting at given strong signal for Gulf moisture
making its way up into southern Wisconsin by Saturday morning.
Resultant PWATs during this time would range between one and two
standard deviations above average. Regardless, forecast
confidence remains on the low side for the time being.

Early week precip chances... Still some uncertainty with the
early week system. Additional chances for wintry precip are
expected to arrive to the western Great Lakes starting Sunday
afternoon ahead of a robust trough that will make its way from
the Rockies up to the Midwest by late Monday night. This trough
will spin up a Colorado low which will potentially track north and
east to affect the Great Lakes region. The exact track of this
low is still extremely variable, thus precip timing and amounts
are still uncertain. Snow and rain both look to be possible with
this system, although pinpointing the transition from rain to snow
will continue to be a hindrance to the forecast.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 652 AM CDT Wed Mar 27 2024

A mix of VFR/MVFR conditions are expected today into tonight,
with a few IFR conditions possible across northern WI. Snow
showers and flurries will continue as an upper level disturbance
tracks across the area. Lowest ceilings/visibilities will be
across northern WI in any heavier snow shower activity. Partial
clearing is expected this morning and again overnight. W/SW winds
will gust up to 30 kts today and up to around 20 kts tonight.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION.....Bersch/Goodin
AVIATION.......Bersch


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