Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 111006
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
406 AM CST Mon Dec 11 2017

.SHORT TERM...(Today and tonight)
Issued at 406 AM CST Mon Dec 11 2017

Strong upper level low propagating through the region causing all
sorts of concerns. Initially, precipitation associated with the
vorticity advection across the southern parts of the region is
falling as mostly liquid, and leading to icy roads where
temperatures are below freezing. With that said, temperatures are
rising above freezing which is limiting impacts.

Cold front is currently (10z) situated just north of the
International border, and set to quickly propagate from north to
south through the region this morning. Current radar imagery not
very impressive, and although snow showers will occur with the
fropa, visibility will likely not be limited too much. Winds will
increase, and the main question revolves around magnitude (i.e.
will a wind advisory be needed?). Strong wind indicators (pressure
rise max, cold air advection, winds aloft) would suggest sustained
30mph gusting to over 45mph, but current observations upstream do
not support these values. Most likely a situation where we see a
a brief period (less than an hour) of wind advisory speeds with
the fropa. Winds will begin to diminish by late morning. The other
concern will be flash freeze potential with moist roads and
temperatures above freezing before the fropa. Will monitor, but
roads may have enough time to dry before temperatures drop below
freezing.

.LONG TERM...(Tuesday through Sunday)
Issued at 406 AM CST Mon Dec 11 2017

The parade of clippers out of Canada continues with the grand
marshall leading the parade around the Wednesday timeframe. Guidance
is still struggling with interaction between a compact but strong
vort max rounding the western ridge near southern British Columbia
and energy originating from more northern Canada. However it does
seem guidances wants to keep the former further west into eastern
Montana perhaps preventing phasing between the two once shown
before. Regardless, light snow and elevated winds are expected
Wednesday into Thursday.

Behind the grand marshall comes another clipper shortly after around
late Friday into Saturday. It is advertised that there may be a bit
more moisture to work with as the source air mass will not have as
much time to be modified originating from the Pacific northwest as
opposed to deeper into Canada. This is a result of flattening of the
western ridge which could also bring warmer temperatures into the
region.

Several pieces of energy emanate from the US Pacific northwest out
of the barrel of a more zonal upper level jet max pointed towards
southern British Columbia/Washington state. Interaction with a
Pacific atmospheric river will supply moisture for these pieces of
energy to play with towards the late weekend. Ensemble guidance is
highlighting one piece of energy around the Sunday/Monday timeframe
to cross the region bringing elevated precipitation chances.

Temperatures will continue to be above normal as colder air stays
trapped in the eastern trough. Normal temperatures this time of year
are in the lower 20s for highs to mid single digits above zero for
lows.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1150 PM CST Sun Dec 10 2017

VFR conditions for most of the RRV/E ND overnight but turning MVFR
or IFR for a time Monday morning as winds turn north and lower
cigs move south. North winds gusty at times as well to 30 kts in
the RRV and DVL. Snow more of an issue at BJI but that will taper
off by morning. I do expect clearing from the north Monday midday
and aftn.

&&

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

$$

SHORT TERM...TG
LONG TERM...CJ
AVIATION...Riddle



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