Area Forecast Discussion
Issued by NWS Grand Forks, ND

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473
FXUS63 KFGF 220002
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
602 PM CST Sat Jan 21 2017

.UPDATE...
Issued at 602 PM CST Sat Jan 21 2017

Forecast update addresses fog issues beginning to develop across
portions of southeastern North Dakota into the southern Red River
valley. Web cams showing fog development from Tenney, MN through
the Oriska rest stop east of Valley City...to include Gwinner that
is now showing 1/4SM visibility. Will issue a dense fog advisory
for the I-94 corridor and south...to include Cass/Clay counties as
well as western Otter Tail. Confidence not as high for the Fargo
Moorhead area but certainly expect visibilities less than one
quarter mile to develop in far western Cass and far southern Clay
over the next couple of hours...especially since Moorhead ob
currently showing zero dewpoint depression and calm winds. Dense
fog advisory will be in effect through noon Sunday.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 253 PM CST Sat Jan 21 2017

Same challenges continue for tonight with fog, drizzle and
potential for freezing pcpn later this evening possibly impacting
travel.

Broad upper trough remains over the n central US. From water
vapor imagery appears to be a weak mid level shear axis in central
ND shifting east. A weak surface trough bisecting ND from NW-SE
also expected to drift east tonight. Ahead of these features there
are some lower condensation pressure deficits and there is some
weak isentropic lift from the valley west which weakens overnight.
With some spotty radar returns over the far western fa will keep
some chance pops for measurable pcpn. Only catch is soundings
more supportive of drizzle vs r/zr/s. For this will limit any
measurable pcpn potential to the west and later shifts will have
to adjust if necessary. Overall not much drop in temperatures
overnight as in the past few nights although may be a little
cooler in the nw. Visibility over the west has improved so degree
of fog and if dense in question but with all the low level
moisture feel there will be some degree of fog and will keep the
mention in the forecast.

As weak trough passes tomorrow does not appear to be a great deal
of lift so for the most feel the day will be dry. Maintained some
low end pops but confidence low and if anything and continuance of
some dz/fzdz. Temperatures will continue to be above average but
maybe a tad cooler with some cooler air moving in.

.LONG TERM...(Sunday night through Saturday)
Issued at 253 PM CST Sat Jan 21 2017

The advent of more westerly upper level flow Sun night should start
to scour out most of the stratus/dz/fzdz with areas of -sn becoming
more prevalent as column cools with time. Most if not all of this
pcpn will be east of the valley Sun night. Mon will be dry but will
still offer a fair amount of cloud cover in the absence of any
strong high pressure. Guidance differs a bit on the track of the
next system for Tue but it appears that movement through Iowa or
extreme southern MN will still brush the far southern forecast
area with minor snowfall amounts.

Wed through Sat...

12z GFS/ECMWF continue to indicate low pressure and associated
system moving toward lake Michigan as this period begins on Wed. It
still appears that the northern edge of the pcpn shield should clip
parts of SE ND and the southern tip of our MN lakes region as it
pulls out. This is handled well in the fcst with minimal
accumulations over this part of the forecast area. Cyclonic flow and
some upper level trough could lead to brief periods of light snow
region wide during Wed into Thu. Temps will be generally dropping
through the week albeit still above average with highs in the 20s
instead of the 30s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 602 PM CST Sat Jan 21 2017

Expect primarily IFR cigs with lowering visibilities in the
southern RRV this evening. May see some brief periods where cigs
increase into MVFR range but this should be short lived.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Dense Fog Advisory until noon CST Sunday for NDZ038-039-049-052-
     053.

MN...Dense Fog Advisory until noon CST Sunday for MNZ003-029-030-040.

&&

$$

UPDATE...Speicher
SHORT TERM...Voelker
LONG TERM...WJB
AVIATION...Speicher



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