Area Forecast Discussion
Issued by NWS Bismarck, ND

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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

FXUS63 KBIS 160528

Area Forecast Discussion
National Weather Service Bismarck ND
1228 AM CDT Fri Mar 16 2018

Issued at 1214 AM CDT Fri Mar 16 2018

Bowman radar shows the reflectivity continues to trend to the
west as the h500 low develops into the central plains with a
negatively tilted narrow h500 ridge providing enough subsidence
across North Dakota to suppress most of the vertical motion and
mid clouds. Will leave the current dry forecast in place with just
a sliver of action across the southwest and far west tonight.
Latest surface observation from Baker MT now reporting freezing
drizzle so expect a mix of snow/sleet/rain southwest with limited
qpfs tonight. This area will transition to light snow by morning.

UPDATE Issued at 927 PM CDT Thu Mar 15 2018

Very little change with this forecast update. Current radar
observations continue to show virga across much of western North
Dakota. The 00 UTC observed sounding at Bismarck showed a deep layer
of very dry air at mid-levels. Forecast GFS/NAM Bufr soundings
show this layer of dry air persisting into tomorrow at Bismarck,
Dickinson, and Williston. Therefore, the chances for any
precipitation to reach the ground tonight are low. The best
chances for precipitation to reach the ground will be across far
southwest North Dakota, where the mid-level dry air is not as
deep. Any precipitation that does make it to the ground will
likely fall as light freezing rain, assuming temperatures do not
cool down to the wet-bulb in the low-level dry layer.

UPDATE Issued at 647 PM CDT Thu Mar 15 2018

Little change with this forecast update other than for observed
trends through 23 UTC. Dry air below 600mb has thus far, and is
expected to continue to significantly limit the potential for
precipitation to reach the ground this evening and tonight. There
does appear to be a brief window for possible light freezing rain
across extreme southwest North Dakota in the 03-06 UTC timeframe
per the 18 UTC GFS/NAM Bufr soundings at Baker. This would
assume that the warm layer does not cool to the wet-bulb given
the dry air that remains.


.SHORT TERM...(This evening through Friday)
Issued at 207 PM CDT Thu Mar 15 2018

Light snow and a wintry mix in the far western counties will be
the main forecast concern for the short term period.

Water vapor imagery depicted a large upper level trough centered
off the coast of Oregon. Embedded shortwaves were moving through
meridional flow over eastern Wyoming and Montana. An associated
surface low was centered over northern Wyoming with a surface high
to the northeast centered over Manitoba. Cloud cover was observed
over the west and south central associated with the active
south/southwest flow. Clear skies were to the north central and

With the upper low almost stationary and flow over Montana
shifting to the northwest, the focus for synoptic forcing was
focused to the west of our border. High-resolution models indicate
a north-south oriented area of precipitation forming this evening
along and west of the Montana/North Dakota border. A few radar
returns were detected over Slope/Billings/Stark counties at the
time of this discussion however there was no evidence of
precipitation reaching the ground. Model soundings for our far
west indicated a persistent 850-700mb dry layer through this
evening, supporting the sporadic chances for precipitation this
evening depicted by high-res guidance. Precipitation that does
reach the ground will have the chance to be any type
rain/snow/sleet given a warm mid-level nose shown by forecast
soundings in the west. The mid-levels cool through the night
switching any light precipitation to all snow through Friday

Through the day Friday a more potent shortwave moves northeast
through Wyoming with associated isentropic lift bringing light
snow to southwest and south-central North Dakota. A rain-snow mix
may be possible in the west where temperatures rise above freezing
in the afternoon hours. East-southeast flow keeps temperatures
mild on Friday with highs in the low to upper 30s.

.LONG TERM...(Friday night through Thursday)
Issued at 207 PM CDT Thu Mar 15 2018

Friday night the aforementioned shortwave lifts north dragging the
associated moisture plume and light snow into northwest North
Dakota before exiting early Saturday morning.

Southwest flow aloft over the Wyoming/Montana sets up after the
previous wave passage, deepening a surface low to our southwest on
Saturday. In the warm sector of the low, southerly flow brings
high temperatures into the upper 30s and low 40s for southwest
North Dakota with low to mid 30s in central and northwest North

The next chance for precipitation arrives with a northerly flow
Canadian low on Sunday. Temperature profiles indicate a rain/snow
wintry mix is possible with this system, however placement,
timing, and amounts of precipitation still has some moderate
disagreement from 12Z model guidance. A blend of guidance brings a
long period of light snow Sunday night through Monday night in the

Ensemble guidance indicates a western ridge building beginning
Tuesday, bringing a gradual warming trend to the area.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1214 AM CDT Fri Mar 16 2018

Slow moving surface trough from Nebraska northwest into Montana
will remain nearly stationary through Friday. High pressure across
eastern North dakota will maintain an easterly surface wind. VFR
conditions are forecast through the 06z TAF period. The only
exception will be KDIK which may see some light snow and MVFR
ceilings after 02Z.




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