Area Forecast Discussion
Issued by NWS Green Bay, WI

Current Version | Previous Version | Text Only | 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 44 45 46 47 48 49 50

FXUS63 KGRB 260439

Area Forecast Discussion
National Weather Service Green Bay WI
1039 PM CST Wed Nov 25 2020

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Thursday
Issued at 242 PM CST Wed Nov 25 2020

Light rain or drizzle is possible in east central
Wisconsin through the evening hours from moisture associated with
the low pressure system moving from Indiana to southeast Lower
Michigan. There could be a little drizzle or patchy fog further
west. Skies should remain cloudy as moisture is trapped below a
temperature inversion. Lows tonight will be about ten degrees
above normal due to cloud cover and mild temperatures aloft.

Thanksgiving Day will start out cloudy, but there should be some
breaks in the clouds in the afternoon as southwest winds increase
a bit ahead of an approaching cold front. Highs will be five
degrees above normal.

.LONG TERM...Thursday Night Through Wednesday
Issued at 242 PM CST Wed Nov 25 2020

The extended forecast mainly revolves around what will happen early
next week as two pieces of energy phase together. There are many
questions left to be answered as models continue to change from run
to run and day to day.

Thursday evening through Saturday...Quiet conditions with above
normal temperatures are anticipated through this period. An upper-
level trough/shortwave will slide across the region on Friday,
however, due to limited moisture, not expecting any precipitation
with its passage. High temperatures will be the warmest on Saturday
with readings in the 40s, and possibly a few spots reaching 50

Rest of the extended...Model guidance continues to show two pieces
of energy eventually phasing together sometime early next week. A
closed low will slide across the southern U.S. from TX/OK to the
Tennessee River Valley Sunday into Monday. At the same time, an
upper-level trough will dig over the Northern Plains/Upper
Mississippi Valley before phasing with the closed low over the Ohio
River Valley/Tennessee River Valley. There is some agreement
bringing moisture over northern Wisconsin Sunday night as a result
of the upper-level trough and north/northwest winds. If models
continue to show this feature in subsequent runs, PoPs will have to
be added to the forecast across north-central Wisconsin. Although,
the two pieces of energy appear to phase together east of the
region, there is some indication of the eventual stacked low moving
north over Lake Erie and then retrograding over Lower Michigan,
which would bring snow and strong winds to the forecast area on
Tuesday. However, not all models are in agreement with this
solution. In fact, the latest 12z GFS has the stacked low moving
northeast over the Appalachian Mountains, keeping the forecast area
completely dry. With many questions left to answer and models
consistently changing from run to run and day to day, did not
refrain from the blend of models during this time. However, one
consistent factor is temperatures cooling down to below normal or
near normal for the beginning of next week after the upper-level
trough passes over the region.

.AVIATION...for 06Z TAF Issuance
Issued at 1039 PM CST Wed Nov 25 2020

IFR/LIFR fog conditions will continue in most places through
around 15z Thanksgiving Day as low-level moisture remains trapped
under an inversion. Patchy light rain or drizzle are also possible
closer to the lake and bay tonight. Ceilings and visibilities
should rise into the MVFR category Thursday morning with some VFR
conditions possible over eastern Wisconsin by Thursday afternoon
if clouds can become scattered. Anticipate ceilings to drop back
to IFR/MVFR conditions for Thursday evening as a weak surface
trough moves through the region.



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