Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 130355

Area Forecast Discussion
National Weather Service Grand Forks ND
955 PM CST Tue Dec 12 2017

Issued at 955 PM CST Tue Dec 12 2017

Surface low currently centered over the northern Red River Valley,
with the precip dropping down from southwestern Manitoba. The high
res models take this band southeastward into the central RRV
before exiting through west central MN before sunrise. Temperatures
with the precip have been very warm, with upper 30s and even low
40s at 9 PM. Air temperatures will stay steady or even slowly rise
for the next few hours before falling later tonight. Road
temperatures are below freezing all but the Devils Lake Basin.
Some rain freezing on contact with the ground will be possible,
particularly over the northern RRV where road temps are in the
20s. Even if not much freezes overnight, with dropping
temperatures during the morning hours think that roads wet from
the rain along with melted slush in some areas will refreeze.
Strong winds tomorrow along with reduced visibilities with those
spots that get snow showers will only make traveling more of a
headache. Will continue to keep the headlines we have going, with
wording hitting the later part of the advisory after temperatures
drop a bit harder. The NAM and some of the high res models have a
decent amount of QPF with freezing rain over the southeastern
counties as the band exits. Think some of this is overdone, but
will keep an eye in future updates in case the advisory needs to
be expanded to the southeast.


.SHORT TERM...(This evening through Wednesday)
Issued at 256 PM CST Tue Dec 12 2017

Temperatures have warmed very nicely late this afternoon. The
warmest spots are just west of the Red River Valley. Winds have
not switched to the southwest to west in the northern valley or
east of the valley. Will probably not have a true diurnal temp
curve tonight. There will likely be additional warming through
sunset, then probably steady or even warming temps yet in some
areas, before a fall very late. With the warm temperatures aloft,
still looking like there will be some sort of mixed pcpn again
developing later this evening. Thinking it will hold off until
late evening in the north and several hours later in the south.
The NAM12 and GFS20 both develop a thin band of higher pcpn
values, which would correspond to potentially greater impacts
between midnight and sunrise. Both models show this potential area
to be the central Red River Valley into west central MN.
Confidence not great with this, but have to keep it in mind.

Greatest confidence is the strong wind potential developing behind
the mixed pcpn potential. Thinking it will lag behind the mixed
pcpn potential by about 3 to 6 hours or so. Therefore the
strongest winds should be arriving in the time prior to sunrise
probably through early afternoon. Still thinking gusts up in the
50 to 55 mph range will be possible, especially in the valley.
With the expected temp fall through the morning, any mixed pcpn
would change to light snow. Not looking at a lot of snow during
the day, but enough that when combined with the snow, vsbys below
a half mile will be likely. Not expecting these low vsbys to be
there continuously, but periods of them. To handle the expected
weather types mentioned above, have elected to go with a winter
weather advisory for the Red River Valley and west for the
combination of mixed pcpn and low vsbys due to blowing snow. Have
less confidence of the mixed pcpn for areas east of the valley,
and there will be less wind there too. Will issue an updated
special weather statement to cover the mixed pcpn potential east
of the valley. Conditions should begin to improve by late Wed

.LONG TERM...(Wednesday night through Tuesday)
Issued at 256 PM CST Tue Dec 12 2017

Main impacts will continue to be clipper systems in NW flow aloft
and potential precipitation combined with wind for each clipper.
Track of each clipper and the blyr temp profile will continue to
allow the threat of a period of mixed phase precipitation. The next
couple of clippers will be Thursday and Friday. Thursdays appears to
bring light pcpn in the west and Fridays in the east. Neither system
appears to be a strong wind producer. Saturdays system appears a bit
more complex with an extended time frame for impacts as the ridging
in the west deamplifies. Models remain wide spread with a possible
central plains piece of energy merging with the southern stream and
developing a more robust system to the south of the FA Sunday.
Monday and Tuesday appear less active as of now. Timing in this flow
remains challenging 6 and 7 days out to say the least.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 632 PM CST Tue Dec 12 2017

IFR ceilings continue at KBJI, and that trend will continue
through the TAF period. The other TAF sites remain VFR, but
conditions will slowly deteriorate towards morning. A band of
mixed precip could bring some FZRA during the 06-12Z time frame,
but not confident enough to include at this point at any one TAF
site so will monitor and amend as needed. All sites should be MVFR
or lower by 15Z at the latest, with some IFR ceilings also at
times. Winds will increase out of the northwest to over 25 kts
sustained and gusts near 40 kts by morning. Some snow showers
could also create some lowered visibility at times with the strong
winds, but it is unknown at this point if any of these showers
will affect the airports. Winds should start to come down late in
the period.


ND...Winter Weather Advisory until 3 PM CST Wednesday for NDZ028>030-

     Winter Weather Advisory until 3 PM CST Wednesday for NDZ006>008-

MN...Winter Weather Advisory until 3 PM CST Wednesday for MNZ002-003-

     Winter Weather Advisory until 3 PM CST Wednesday for MNZ001-004-



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