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Office: BIS

FXUS63 KBIS 131824
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1224 PM CST Wed Dec 13 2017

.UPDATE...

Issued at 1222 PM CST Wed Dec 13 2017

Highest wind potential now behind us as gusty mixing winds will be
on the decrease here on out. Last few hours have also seen no
observing sites at or above wind adv criteria. Thus all wind
headlines were expired with this product issuance.


UPDATE
Issued at 915 AM CST Wed Dec 13 2017

Quick update to expire all but my south and east from the wind
advisory as winds continue to diminish. A few stronger gusts
remain possible south over the higher terrain and east near better
gradient forcing. Will also maintain the mention for patchy
freezing rain northeast.

&&

.SHORT TERM...(Today and tonight)
Issued at 400 AM CST Wed Dec 13 2017

Wind advisory and patchy light freezing drizzle and/or light snow
highlights the today period. Another clipper arrives tonight with
light snow and minor snowfall accumulations.

Per observations and BUFKIT soundings regarding the wind advisory,
it is marginal on the sustained winds and gusts, and we should be
able to chip away and remove counties from west to east through
the morning hours.

Latest water vapor imagery indicates an active northwest flow
continues into North Dakota, as successive clippers are passing
through just about every 24hours. This mornings clipper type cold
front is well south of the state, with its associated upper level
shortwave now pushing into northern South Dakota. Large chunk of
stratus is quickly shifting south from eastern Saskatchewan and
Manitoba, and into the Turtle Mountains as of this writing.
Followed the NBM sky grids which seemed to capture the clouds
well. Essentially once the stratus arrives, expecting it to linger
for the day along and east of a line from Williston to Bismarck,
which seems to line up along the low level baroclinic zone.
Farther to the west, low clouds will be in/out with breaks of
sunshine from time to time, especially in the southwest. Cooler
today with highs in the 30s.

The next mid/upper level shortwave supporting our next surface
clipper/cold front per water vapor imagery was located near
Yellowknife in the Northwest Territories of Canada. This will dive
southeast today, arriving into northwest ND by 06z Thursday.
Large scale ascent will increase and push from northwest to
southeast 06z-18z Thursday. GEFS Plumes across western/central ND
show decent clustering between 0.05 and 0.10 inch liquid amount
range. With average snow ratios around 13 to 1, forecast snowfall
totals between a half inch and one and one half inches from
tonight through Thursday morning can be expected. Despite this not
being a large amount of snow, it will occur during the Thursday
morning commute, so will message this mostly through social media
at this time.

One area will need re-evaluating is in southwest ND Thursday
morning, as strong winds, near or into advisory level per BUFKIT
soundings, may combine with snow for low visibilities and impact
to travel. Future shifts can re-evaluate the soundings with the
latest data to see if these trends continue. Elsewhere, winds will
range between 15 and 25 mph, with patchy blowing snow.

.LONG TERM...(Thursday through Tuesday)
Issued at 400 AM CST Wed Dec 13 2017

No shortage of additional clippers through the long term. As of
now, it appears Friday night, Saturday night, Monday, and late
Tuesday into Wednesday, are the favored time periods for each
passage through western/central ND.

A chance of snow can be expected with each clipper, along with brisk
winds/15mph to 25 mph. Strong winds are not expected at this time.
Trends continue for much colder air to pour into the northern high
plains late next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)

Issued at 1222 PM CST Wed Dec 13 2017

Gusty winds to 30kt and stratus will be the main aviation hazards
this afternoon. Large area of MVFR cigs will persist across
central and eastern terminals through the period. KISN-KDIK will
toy with MVFR cigs today, but overall should remain VFR. Next
clipper arrives tonight, with light snow and MVFR to pockets of
IFR conditions persisting/developing at all terminals for the
remainder of the period, with perhaps some improvements after 15Z
Thursday.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

UPDATE...NH
SHORT TERM...KS
LONG TERM...KS
AVIATION...NH



Office: FGF FXUS63 KFGF 131807 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 1207 PM CST Wed Dec 13 2017 .UPDATE... Issued at 1153 AM CST Wed Dec 13 2017 Winds have decreased and visibilities have increased and as such have let the headlines go. Upstream obs showing minimal in the way of snow streamers within the secondary push of cold advection. Will continue to have the possibility of some patchy fog or mist or freezing drizzle across the ND side with lack of ice nuclei aloft. On the MN side light snow is falling as ice nuclei is present and will persist into the early evening. && .SHORT TERM...(Today and tonight) Issued at 357 AM CST Wed Dec 13 2017 Surface low is located near Alexandria (10z) and will continue to propagate southeast. Associated precipitation is about to exit the region. Current air/road temperatures suggest mainly rain within and west of the valley, with freezing rain east of the valley. With that said, had a situation here at the office in Grand Forks where the rain occurred with air temperature above freezing while road temperatures where below freezing. We began with icy sidewalks, which became wet/slushy. These wet/slushy sidewalks are now icy as the temperature has quickly dropped into the mid 20s. Latest RAP guidance indicates a push of strong cold air advection pushing southward through the Red River Valley right behind the precipitation which is causing any wet/slushy roads to quickly freeze. Any wet/slushy roads across the southern Red River valley should quickly freeze this morning as well. The morning commute will be hazardous. There is another push of cold air advection down the valley again later this morning and afternoon with the passage of another upper level wave. This should reinforce mixing of winds aloft to the surface and continue to expect wind advisory criteria. The main question will revolve around any additional winter weather impacts. Still think the potential exists for snow showers along and east of the valley, which combined with strong winds may reduce visibility at times. The next clipper brings snow chances to central/eastern North Dakota later tonight. .LONG TERM...(Thursday through Tuesday) Issued at 357 AM CST Wed Dec 13 2017 Upper air pattern continues with the northwest flow aloft. Short waves continue to roll over the upper ridge over western North America and drop into the Northern Plains. Also short waves will drop south from Northern Canada and mainly move east of the forecast area. However they may affect the far eastern zones. One such short wave may affect the northeast zones Thu afternoon. Next upper level trough over the eastern Pacific will approach the forecast area on Fri. Models generally agree on warm advection precip for Fri and upper level system to affect the area Sat. Long wave pattern maintains a long wave ridge over the eastern Pacific or the West Coast. Long wave trough remains over eastern Canada and the northeast US. Upper level pattern becomes more zonal on Mon but does re-amplify somewhat on Tue. GFS and ECMWF were in reasonable agreement through Mon. The ECMWF becomes a faster solution thereafter. High temperatures were increased two to three degrees for Sat and increased a degree for Mon. Little change to temps for Sun and Tue from yesterdays forecast. && .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) Issued at 1153 AM CST Wed Dec 13 2017 IFR and MVFR CIGs impacting the TAF sites this afternoon along with gusty north winds 20 to 30kts. -SN or FZDZ is possible also. Winds will quickly weaken this afternoon. Overnight -sn is possible. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...JK SHORT TERM...TG LONG TERM...JH AVIATION...JK