Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 291839
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1239 PM CST Tue Nov 29 2016

.UPDATE...
Issued at 1230 PM CST Tue Nov 29 2016

Accumulating precip is confined to the far western edges of the FA
in Benson county where light snow continues and along a line from
the southern valley into the arrowhead of MN where a mostly rain
mixed with a few wet snow flakes continues to pinwheel to the
southwest. Mid level dry tongue has worked into the FA between
these two areas with some patchy fog, mist or drizzle occurring
underneath the loss of ice crystals aloft. Went ahead and
increased the pops in the southern valley where the highest
confidence exists for continued accumulating precip and
introduced the fog and drizzle, mist into the forecast elsewhere.


&&

.SHORT TERM...(Today and tonight)
Issued at 334 AM CST Tue Nov 29 2016

The forecast challenge for the short term period continues to be
precipitation type, rainfall/snowfall amount and temperatures. The
majority of eastern North Dakota into the Red River Valley is
ranging from 34 to 36 degrees...with temps around the 40 mark in
the northern valley. The latest surface obs indicate the surface
low in the vicinity of Wahpeton with trough extending through
Otter Tail county and into Crow Wing county MN. The low has begun
to gradually drift to the east and should take a southeast
trajectory to near Alexandria by mid afternoon...although the NAM
is a bit further to the northeast with the upper vort over
northeastern ND. Warm air advection from the NE has brought
surface temps across Devils Lake into the mid 30s and precip
changed over to snow last evening, with most recent web cams
showing at least some melting of the snow they received yesterday
morning. Snow is being reported at Valley City with rain likely
now at Cooperstown...and the rain-snow line appearing to be along
a line from Valley City possibly into the Rugby area. The main
batch of precip moving northeast out of northeastern ND is moving
into the Griggs/Eddy/Nelson county region and is rain or a
rain/snow mix.

As the surface low begins to accelerate east, precip over central
ND as well as a slightly cooler near surface layer will help
change rain back over to snow in the far western regions into
portions of southeastern ND, but the southeast will quickly return
to rain while a wintry mix is not expected to move into the valley
until near sunset. This slow transition will limit the best
snowfall accumulations once again to about the Highway 281
corridor and west, where a second round of 1 to 3 inches is
possible by 00Z Wednesday. As the surface low pulls east, the
tighter pressure gradient over central ND as well as stronger cold
advection into the low pull cause some gustier winds but snow will
be wet enough that blowing/drifting snow will not be an issue. The
surface low moves into northwestern WI by 12Z Wednesday. Most
regions will receive up to one quarter of an inch of rainfall
with higher amounts across the south and west. Only minor
accumulations are expected west of a Devils Lake to Valley City
line by morning as surface temperatures stay in the mid 30s.

.LONG TERM...(Wednesday through Monday)
Issued at 334 AM CST Tue Nov 29 2016

Models are indicating a shallow saturated level being overrun by
dry air aloft Wednesday afternoon. The GFS keeps the top of the
saturated level near the ice crystallization level, however
blended solutions dry that layer out. Light snow is expected to
continue through noon Wednesday, with only minor accumulations,
however if the lower layers of the atmosphere do not dry out and
end precip, there is a chance for drizzle or freezing drizzle
expanding north to south during the afternoon hours. Only minor
accumulations of ice are possible...mainly on untreated roads
however the warm road temperatures will make accumulation
difficult. Grids indicate drizzle or light snow with some
uncertainty in the depth of the shallow saturated layer.

Lingering isolated snow showers will continue into Thursday
morning with thinning clouds during the afternoon hours, however
temps are expected to stay around freezing throughout the day. A
much colder and drier air mass will move over the area Thursday
night and temps may fall into the mid 20s, however with cloud
cover expected much of the night...model guidance may be a bit too
cold.

Friday through Wednesday...

Surface high pressure will be in control on Friday with the ridge
axis over the Devils Lake basin...with light winds and high temps on
Friday in the upper 20s.

By Saturday...high pressure retreats toward the Ohio valley and will
see return flow across the region ahead of the next system. A trof
of low pressure will cross the area on Sunday...but limited moisture
will result in some light snow with little accumulation expected.

Otherwise...a more organized system looks to develop by late Monday.
Southerly winds should become a bit breezy with a tightening
pressure gradient...and temperatures will be slightly warmer. Some
precipitation should occur right at the end of the forecast
period...with mainly light snow in the north and possibly a mix in
the south.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1230 PM CST Tue Nov 29 2016

IFR CIGS to be prolonged at all TAF sites as saturated airmass
remains in place. Periodic episodes of BR or DZ mixing with -RA
or -SN overnight can not be ruled out. North winds will continue
through the period with a gradual drying possible from west to
east beginning tomorrow mid morning at dvl.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&

$$

UPDATE...JK
SHORT TERM...Speicher
LONG TERM...Hopkins/Speicher
AVIATION...JK



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