Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 150417
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1017 PM CST Tue Feb 14 2017

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

.UPDATE...
Issued at 1001 PM CST Tue Feb 14 2017

Will be lowering pops across far north central WI, and just going
with scattered snow showers in Vilas county, despite favorable
trajectories and increasing over-water instability. Nothing more
than flurries have been reported in Vilas county so far, and with
dew points in the single digits upstream of western Lake
Superior and lowering inversion heights, prospects aren`t very
good for any significant development.
&&

.SHORT TERM...Tonight and Wednesday
Issued at 235 PM CST Tue Feb 14 2017

The primary forecast challenges to be precipitation trends into
this evening accompanying a cold front and then amount of lake
effect snow showers across north-central WI tonight into Wednesday
morning.

The 20z MSAS surface analysis showed an area of low pressure over
southeast Ontario with a cold front extended southwest through
central WI into northern IA. High pressure stretched from central
Canada southward into the central Plains. The radar mosaic
indicated several bands of precipitation along and behind the cold
front with visibilities briefly getting knocked down to under 2
miles in heavier (albeit very brief) snow squalls.

Northeast WI to reside on the cold, cyclonic side of an exiting
shortwave trough tonight with a colder/blustery air mass taking
over for the overnight hours. The CAA, coupled with favorable
trajectories, should be able to produce some lake effect snow
showers/flurries over north-central WI tonight. Accumulations
appear to be minimal due to low inversion heights and delta-T
values only in the middle teens. Perhaps up to an inch of snow
possible over the Vilas County snowbelt with less than one-half
inch expected farther south and east. Min temperatures to range
from 10 to 15 above north-central, to the lower 20s east-central
WI.

The lake effect snow threat will continue through at least
Wednesday morning before the cyclonic flow weakens and winds begin
to back to the west-northwest, making trajectories become
marginal. Do not anticipate much more than a couple tenths of an
inch of accumulation over the Vilas County snowbelt. Otherwise,
the rest of northeast WI is expected to be dry, but mostly cloudy
as mid/high clouds overspread the region as some warmer air aloft
moves toward WI. Max temperatures will be noticeably colder than
previous days behind the departed cold front. Look for readings to
be closer to normal with lower to middle 20s north, mainly 25 to
30 degree range south.

.LONG TERM...Wednesday Night Through Tuesday
Issued at 235 PM CST Tue Feb 14 2017

Dry and mild weather weather expected through Sunday,
as a large upper ridge approaches from the Plains. Highs should
approach or exceed 50F in some areas Saturday, Sunday and Monday.

Dewpoints should stay below freezing through Saturday or Sunday,
so not expecting low clouds or fog until they do. This will also
slow snowmelt and river rises.

An upper trough lifting northeast from the northern Plains into
Canada and an approaching surface cold front will bring south
winds and Gulf moisture to the region Monday afternoon and night
along with a good chance of rain. The rain and high dewpoints will
likely produce fog and rapid melting of whatever snow is left on
the ground. This could cause rising rivers and ice jams in some
areas.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1001 PM CST Tue Feb 14 2017

Scattered lake effect snow showers or flurries will persist
across north central WI into Wed morning, but the main impacts
should be confined to Vilas county. The remainder of the region is
forecast to be dry overnight into Wednesday evening. Although
a stratocumulus deck is expected to spread back across the region
overnight into Wed morning, conditions should remain VFR at most
locations. Cloud bases may briefly drop into the MVFR range late
tonight into Wednesday morning across parts of northern and
central WI, so will probably carry a tempo group there.
The stratocumulus should break up as a ridge of high pressure
arrives in the afternoon, followed by increasing mid-level
clouds during the evening.
&&

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

$$

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



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