Area Forecast Discussion
Issued by NWS Bismarck, ND

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KBIS 250556
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1156 PM CST Fri Feb 24 2017

.SYNOPSIS...
Issued at 304 PM CST Fri Feb 24 2017

Per GFS/ECMWF height fields and PNA/Pacific North American
Pattern...all support a pattern change commencing by 240hr/March
6th. Currently, an upper ridge extends through the Gulf of Alaska
with a downstream west coast trough and northwest flow into North
Dakota. This is forecast to be replaced with an upper trough in
the Gulf of Alaska and a building ridge downstream along the west
coast by March 6th. The PNA/Pacific North American Pattern goes
negative and peaks just before March 1 (should represent the peak
of the coldest air), then becoming positive at the end of the
first week in March. This would correspond to a warming trend with
the upper ridge developing along the west coast during this time.

Until then, expect an active period under the aforementioned
northwest flow. Between the GFS and ECMWF, between 6 and 8 weather
systems are forecast to work their way through western and central
North Dakota through next Saturday. Essentially, expect pops in
the forecast on a daily basis. However, nothing at this time
signals for any significant precipitation event, mostly progressive
and weak systems resulting in minor snowfall accumulations.

In addition, ice jam impacts are possible along the Yellowstone
River and the Missouri River upstream of Williston over the next
several days. Please see the hydro discussion below for further
details.

&&

.UPDATE...
Issued at 1146 PM CST Fri Feb 24 2017

Several weak surface lows will move across west and central North
Dakota during the next 24 hours. The first will track a weak cold
front through the region early this morning. NWS radars show a
band of light snow associated with the front moving into
northwest and north central North Dakota. For this aligned the
POPS to follow the trends through 6 am. Snow accumulations will be
light generally less than an inch tonight.

UPDATE Issued at 929 PM CST Fri Feb 24 2017

Increased PoPs with this update for most of the area for tonight
through Saturday in a high PoP/low QPF event favored by the 18-00
UTC global suites. This is in association with a weak wave across
far north central Montana late this evening that will impact
western and central North Dakota tonight, and a stronger
wave/clipper for Saturday. With steep lapse rates, the 18 UTC GFS
and 00 UTC NAM favor an enhanced area of snowfall Saturday
afternoon and evening from northwest North Dakota through the
upper James River Valley where up to a quick two inches of snow
are possible.

UPDATE Issued at 614 PM CST Fri Feb 24 2017

The latest observations were blended into the forecast, including
an adjustment to POPs to reflect current radar trends. Otherwise,
no major changes were made to the forecast.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 304 PM CST Fri Feb 24 2017

Latest water vapor imagery shows a vorticity lobe extending from
Hudson Bay southwest into southern Manitoba, Saskatchewan, and
into Alberta. Another shortwave trough was noted over northern
Alberta southwest into southern British Columbia. Both of these
shortwaves will result in weak surface low pressures to push
through one right after the other. The initial one arrives tonight
northwest and into south central Saturday morning; with the second
system into the northwest Saturday afternoon, then into central
Saturday night. The initial system will produce a couple of
tenths of snowfall for portions of western and central ND; with
the secondary shortwave Saturday night a bit deeper/stronger in
the as noted by the 700-500mb height fields. This will produce
another couple more tenths to around an inch to an inch and a half
across north central ND and into the northern James River Valley.

Lows tonight in the single digits above zero north and east, to
the mid and upper teens west. Highs Saturday wil range from the
upper teens north to around 30 south.

.LONG TERM...(Saturday night through Friday)
Issued at 304 PM CST Fri Feb 24 2017

As mentioned in the short term discussion, an area of light snow
will follow for Saturday night then exits early Sunday morning. A
much weaker system pushes through Sunday afternoon through Sunday
night with little or no snowfall, mainly across the north. The
next system is slated for Monday night through Tuesday night,
with the GFS being deeper and more totals. With the latest
gridded data and model run, the highest snowfall totals are slated
for north central ND with between one and two inches. Expect a
tenth or two elsewhere at this time.

The GFS then pushes through two more systems, one Wednesday
afternoon through Wednesday night, and a second system Friday and
Friday night. These clippers appear stronger than previous systems
during the week as they should be more typical of a clipper
possessing stronger winds and light snow across western and
central ND. The ECMWF is weaker with these clippers. Bottom line
is not a lot of sunshine or quiet weather for any length of time
through the extended. High temperatures will mostly be in the 20s
to lower 30s, with overnight lows in the single digits above zero
to the mid teens.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1150 PM CST Fri Feb 24 2017

At 11 pm CST a cold front extended through northwest North Dakota
into northeast Montana. An area of snow associated with the front
will move through western and north central North Dakota tonight
bringing MVFR/IFR conditions in snow. The snow will spread into
the south central Saturday morning. Additional periods of snow are
possible area wide Saturday afternoon and evening as a stronger
Alberta clipper impacts the area.


&&

.HYDROLOGY...
Issued at 304 PM CST Fri Feb 24 2017

Occasional ice jams due to ice breaking up continue along the
Yellowstone River in eastern Montana. River rises will be
possible on the Yellowstone in North Dakota from Fairview,
downstream to the Missouri River near Buford when ice jams
release. Ice affected rises may also be possible along the
Missouri River from the Yellowstone downstream to Trenton and
Williston. Those with interests along the Yellowstone and Missouri
Rivers near the Montana border should be prepared for the
possibility of rising river levels.

&&

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

$$

UPDATE...WAA
SYNOPSIS...KS
SHORT TERM...KS
LONG TERM...KS
AVIATION...AYD
HYDROLOGY...JJS



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.