Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 200536
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1136 PM CST Sun Nov 19 2017

Updated aviation portion for 06Z TAF issuance
and new information added to update section

.UPDATE...
Issued at 1130 PM CST Sun Nov 19 2017

Clearing skies and light winds have allowed temperatures to
plummet at the typical cold spots in north central WI. Lowered
minimum temperatures significantly there, and made some minor
downward adjustments elsewhere.

&&

.SHORT TERM...Tonight and Monday
Issued at 225 PM CST Sun Nov 19 2017

Main forecast focus to be on temperatures as a surface ridge axis
moves through the region late this afternoon into tonight.

The 19z MSAS surface analysis indicated the ridge axis extended
from the Mid-MS Valley northward along the MN/WI border into the
southwest corner of Ontario. The next system of interest is
located well to our northwest over southwest Canada. Visible
satellite imagery showed a brief break in the clouds over
northeast WI between retreating low clouds to the east and
advancing mid/high clouds to the west. Temperatures were well-
below normal for mid-November.

A west-southwest wind will prevail across the region and draw
milder air into WI tonight as 8H temperatures warm from around -6C
to around 0C. This WAA, coupled with the passage of a 110 knot
upper jet, should bring these mid/high clouds into parts of
northeast WI through the night. Under generally partly cloudy
skies, temperatures are expected to bottom out later this evening,
then either hold steady or slowly rise late. Currently have low
temperatures ranging from 15-20 degrees north-central WI, 25-30
degrees east-central WI. As a side note, if skies over northern WI
were to clear out, temperatures could end up closer to 10 above
due to fresh snow cover.

South winds at the surface and southwest winds aloft will continue
to pull warmer air into WI as 8H temperatures rise to around +6C
by 00z Tuesday. A decent amount of sunshine is expected on Monday,
although there could be some increase in clouds late in the day
ahead of a clipper system moving into extreme southwest Ontario.
Monday appears to be the warmest day of the week as we see max
temperatures reach around 40 degrees far north, upper 40s over
parts of central WI.

.LONG TERM...Monday Night Through Sunday
Issued at 225 PM CST Sun Nov 19 2017

A pretty quiet period of weather is expected this
week, with dry northwest upper flow and two shortwave troughs
moving through. The first should produce light lake effect snow
showers Monday and Monday night, while the second could bring some
light snow or rain towards the end of the week as a clipper passes
by to our north. Temperatures should be within about five degrees
of normal for this time of the year.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1130 PM CST Sun Nov 19 2017

Mid and high level clouds are anticipated through Monday evening.
Light southwest winds are expected overnight, with gusty south
winds developing Monday afternoon and evening.

The main aviation concern is LLWS, which will develop in advance
of a cold front on Monday evening, as southwest winds aloft
increase to 40 to 50 kts.

&&

.MARINE...
Issued at 225 PM CST Sun Nov 19 2017

Pressure gradient is forecast to tighten between high pressure
over the Mid-Atlantic states and the clipper low pressure moving
across southern Canada. A small craft advisory will be issued
starting Monday afternoon. We will have to watch for possible
gales Monday night into Tuesday behind the clipper as winds turn
to the west-northwest.
&&

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

$$

UPDATE.........Kieckbusch
SHORT TERM.....Kallas
LONG TERM......RDM
AVIATION.......Kieckbusch
MARINE.........Kallas



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