Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 121924

Area Forecast Discussion
National Weather Service Green Bay WI
224 PM CDT Mon Mar 12 2018

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Tuesday
Issued at 224 PM CDT Mon Mar 12 2018

The extent of snow showers/flurries remains the main forecast
challenge over the next 24 hours as a cold, cyclonic flow remains
locked over the region.

The 19z MSAS surface analysis showed a pair of very weak areas of
low pressure over eastern sections of the Great Lakes. A ridge of
high pressure resided from west of Lake Winnipeg south through the
central Plains. Most of the forcing and lift this afternoon were
aloft due to mid-level shortwaves dropping southeast and the
location of a strong upper-level speed max. The radar mosaic
picked up on a decent burst of snow showers across Door County
with only spotty flurries or drizzle elsewhere.

Northeast WI to remain on the cyclonic side of a strong shortwave
trough/nearly closed upper low moving southeast across central/
eastern sections of the Great Lakes tonight. Several embedded
shortwaves within this trough will bring enough mid-level forcing
to generate light snow showers and/or flurries over most of the
forecast area. Higher pops to be placed over north-central WI due
to lake enhancement and eastern WI where forcing to be the
strongest. It would appear that any accumulation of consequence
will be limited to Vilas County where one-half to one and one-half
inches of snow is possible. Min temperatures to range from 10 to
15 degrees north-central, to around 20 degrees over east-central

Only subtle changes are expected on Tuesday as the shortwave
trough/closed upper low will be slow to exit the eastern Great
Lakes due to the big nor`easter off the New England Coast.
Therefore, northeast WI to remain stuck in the weakening cyclonic
flow with additional shortwave energy moving southward through WI.
Any snow showers or flurries to be restricted more to eastern WI,
while lake effect for north-central WI to begin diminishing as
high pressure builds into the Upper MS Valley. Tuesday will also
be a bit on the blustery side with gusts of 15 to 25 mph. 8H
temperatures cool a little as well, thus max temperatures are
expected to only reach the middle to upper 20s north/parts of
central WI, upper 20s to lower 30s over the rest of central and
east-central WI.

.LONG TERM...Tuesday Night Through Monday
Issued at 224 PM CDT Mon Mar 12 2018

After a shortwave ridge tracks through the area Tuesday night, a
shortwave and surface trof will move through the western Great
Lakes region on Wednesday. Despite the dynamics, the weather
looks to remain dry as model soundings are quite dry across the

Large scale ridging then works its way in from the west for the
end of the week, which should keep the weather dry through the end
of the week. The weekend gets a bit complicated as the Canadian
model continues to bring a low pressure system through the western
Great Lakes while the ECMWF and GFS models remain dry with high
pressure across the region. Given the upper level ridge in place
will lean towards and drier forecast and keep POPs low for this

Long range models then bring a low pressure system through the
western Great Lakes during the early part of next week. However
with the continued trend of bringing a low pressure system through
the region then backing off there is little confidence in this
portion of the forecast. Temperatures should be at or above normal
for the extended portion of the forecast.

.AVIATION...for 18Z TAF Issuance
Issued at 1235 PM CDT Mon Mar 12 2018

Combination of CAA, passage of mid-level shortwaves, and daytime
heating has allowed mainly low-end VFR cigs to develop/move south
across northeast WI. Still anticipate some mix of rain/snow
showers or sprinkles/flurries to develop this afternoon and then
persist through much of tonight as additional mid-level energy/
lingering cyclonic flow persists over the region. Cigs could
briefly drop into the MVFR range tonight, especially over the RHI
TAF site where lake enhancement also possible. Gusty northwest
winds this afternoon are expected to ease tonight, but pick up
once again on Tuesday. Cannot rule out additional snow showers
and/or flurries on Tuesday as the overall weather pattern is not
expected to change much until Wednesday.



SHORT TERM.....Kallas
LONG TERM......Kurimski
AVIATION.......Kallas is the U.S. government's official web portal to all federal, state and local government web resources and services.