Area Forecast Discussion
Issued by NWS Bismarck, ND

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503
FXUS63 KBIS 240611
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1211 AM CST Sat Feb 24 2018

.UPDATE...
Issued at 1207 AM CST Sat Feb 24 2018

Weak return flow continues overnight. Made a few changes to
temperatures as areas over the southern James River valley have
dropped quickly to well below zero, while other wind prone areas
such as Minot and Dickinson remain in the lower teens. We did
delay the onset of snow a bit on Saturday in the south central.

UPDATE Issued at 939 PM CST Fri Feb 23 2018

Quick update for observed trends through 03 UTC. Return flow
through the night should hold overnight low temperatures in
the 5 below to 5 above range for most areas.

UPDATE Issued at 658 PM CST Fri Feb 23 2018

Little change for the overnight outside of observed trends through
00 UTC. Did scale back the SPS to be focused across Logan,
McIntosh, Dickey, LaMoure and Stutsman counties for light snow
Saturday per trends in the 18 UTC GFS/NAM.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 237 PM CST Fri Feb 23 2018

Highlight in the short term is light snow Saturday into Saturday
evening for portions of south central including the James River
Valley. A Special Weather Statement has been issued highlighting
sub-advisory snow accumulations/with some impacts/inconveniences
to travel.

Latest water vapor imagery shows a southwest upper flow into North
Dakota, depicted as a split flow pattern, with a northern stream
trough over south central Canada, and a Great Basin upper
low/trough in Nevada/Utah. Through the short term period, the
Great Basin upper trough will eject northeast, and link up with
aforementioned Canadian shortwave trough. South Central North
Dakota including the James River Valley will remain on the
northern fringes of the weaker snowfall range. As stated in the
Special Weather Statement, total snowfall accumulations of between
1 and 2 inches can be expected from Bismarck to Jamestown, and
from Selfridge to Ashley. Higher amounts of around 3 inches are
expected over the far southern James River Valley, including
Verona, Ellendale, Oakes and Ludden. The EMC GEFS Plumes for
Bismarck and Jamestown, along with the global/high resolution
model liquid precipiation amounts are in fairly good agreement
with the above snowfall amounts. The NAM/Canadian models indicate
higher amounts of snowfall across the southern James River Valley,
and although this could have some merit and will need watching,
the overall snowfall guidance were below these higher totals.

Current visible satellite imagery and surface observations show
generally clear conditions, as the last of the stratus continues
to dissipate over the Turtle Mountains. Clear early tonight, then
clouds increasing across the south after midnight. Overnight lows
wil range from the lower single digits below zero north to the
lower single digits above zero south. Not as cold south with
increased cloud cover arriving later tonight as mentioned above.

.LONG TERM...(Saturday night through Friday)
Issued at 237 PM CST Fri Feb 23 2018

The light snow will exit the southern James River Valley Saturday
night associated with the southern stream upper trough. Perhaps a
couple pockets of lingering light snow behind the northern stream
upper trough as it slides through late Saturday night, but this
only shows up on the GFS/ECMWF and mainly over the northwest.
Otherwise, expect dry weather Sunday with warm air advection
overspreading western and central North Dakota. This will be
followed by a quick/minor surge of cold air advection Monday as a
fast moving warm front/cold front glides across southern Canada.
Some slight chances for light snow graze northern North Dakota
Sunday night, but very little snow if any is forecast to
accumulate. Highs Sunday will rise into the upper 20s north to
lower 30s south.

Thereafter, Monday through Friday, a split flow continues with an
active southern branch and a weaker northern branch. The weaker
northern branch will push a couple of systems through North
Dakota with little or no precipitation threat. The GFS/EC hint of
a deeper upper trough across the northern Rockies next weekend
which could yield better prospects for precipitation, but time
will tell whether this trend is maintained. For the balance of
next week, dry with highs mostly be in the lower 30s and overnight
low temperatures between 10 and 15 above.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1207 AM CST Sat Feb 24 2018

Light snow will move into far south central ND Saturday morning
and spread northeast with time into the James River valley for the
afternoon. KJMS will likely experience IFR ceilings and visibility
with the light snow Saturday afternoon and early evening. The most
recent model guidance suggests the light snow will stay southeast
of KMOT, and may only briefly impact the KBIS terminal during the
midday hours. We therefore carried only 6SM in light snow at KBIS
with the 06 UTC TAF release, though brief MVFR conditions could
certainly occur.

&&

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

$$

UPDATE...TWH
SHORT TERM...KS
LONG TERM...KS
AVIATION...CJS



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