Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 101456

Area Forecast Discussion
National Weather Service Bismarck ND
856 AM CST Sun Dec 10 2017


Issued at 855 AM CST Sun Dec 10 2017

Main update to the forecast for this morning/afternoon was to
bump up sky cover with increasing clouds from north to south
observed the past few hours. Used a blend of NBM and GLAMP which
seemed to capture the trend rather well. Otherwise the forecast
remains on track for today with chances for light rain maybe mixed
with snow far north mid to late day. Temperatures still on track
as well with low 50s southwest/south central.

UPDATE Issued at 634 AM CST Sun Dec 10 2017

No changes for this morning or today outside of observed trends
through 12 UTC.


.SHORT TERM...(Today and tonight)
Issued at 345 AM CST Sun Dec 10 2017

Another very mild day today, followed by strong winds tonight
highlight the short term forecast.

With a very mild start with 10 UTC temperatures in the 30s across
most of the area, favorable westerly winds through the day,
dwindling snow, and the same airmass in place as Saturday, another
very mild day is expected across most of western and central North
Dakota today. Trended above the 00 UTC guidance consensus,
maintaining the thinking of highs in the 50s southwest and south
central today, 40s northwest and north central with increasing
cloud cover, and 30s across the James River Valley through the
Turtle Mountains with far less mixing.

For tonight, a cold front will rapidly propagate from northwest to
southeast across western and central North Dakota associated with
an Alberta Clipper. Strong northwest winds are expected behind the
front tonight into Monday. The timeframe of the strongest winds
are expected in the 06-12 UTC window when low level lapse rates
and cold air advection increase, coincident with the greatest
isallobaric forcing. However, the 6mb/3 hr pressure rise bubble
and greatest isallobaric forcing are forecast to impact eastern
North Dakota to a greater degree. With 45-55kts at the top of the
mixed layer, wind headlines are certainly possible. However, there
is some uncertainty how efficient momentum transfer will be as
both cold air advection and isallobaric forcing will be modest.

.LONG TERM...(Monday through Saturday)
Issued at 345 AM CST Sun Dec 10 2017

The impacts of two to three clipper systems highlight the
extended forecast.

The 00 UTC global suite is in agreement on two to three clipper
systems to potentially impact western and central North Dakota as
the upper level pattern remains generally unchanged most of the
week as a high over low western CONUS blocking pattern is slow to
break down. The first clipper is expected Tuesday into Wednesday,
a second weaker clipper Friday, and a potential third on Sunday.
Thus, expect a pattern of a mild Tuesday, Friday and Sunday ahead
of the clippers. The 00 UTC suite does suggest the western CONUS
upper level ridge may break down late next week.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 634 AM CST Sun Dec 10 2017

Low level wind shear is possible across western and south central
North Dakota early this morning with strong winds off the surface
in an inversion. A strong cold front will overtake western and
central North Dakota Sunday evening from northwest to southeast.
Strong northwest wind gusts of 30 to 40kts are expected behind
the front Sunday night into early Monday morning. VFR conditions
are expected this morning through the early evening. However,
MVFR/IFR conditions in stratus and a mix of rain and snow is
expected behind the front tonight into Monday.




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