Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 150008

Area Forecast Discussion
National Weather Service Bismarck ND
708 PM CDT Wed Mar 14 2018

Issued at 700 PM CDT Wed Mar 14 2018

In agreement with neighboring offices and despite short term
models, have decreased forecast cloud cover overnight and added
patchy fog south-central, Bismarck to Jamestown and south. Short
term models have overdone extent of low clouds recently and expect
the same this forecast cycle. Although increasing surface pressure
gradient and expectation that wind will pick back up to near 10
mph overnight, have added patchy fog to the area from Bismarck to
Jamestown and to the South Dakota border due mainly to melting
from today. Here the short term models support this decision.


.SHORT TERM...(This evening through Thursday)
Issued at 303 PM CDT Wed Mar 14 2018

Water vapor analysis indicates a broad Pacific trough moving over
the west coast, amplified ridging centered over the front range of
the Rockies, and Northwest flow aloft over the Northern Plains.
Cold air advection from low level northerly flow over the southern
Canadian prairies into eastern North Dakota. Clear skies and light
winds continue this afternoon into the evening under the influence
of upper level ridging.

Overnight, a lee trough deepens over eastern Montana with
low level southeasterly flow over our west. A combination of moist
southeasterly winds and cooler northeast flow out of southern
Manitoba will lead to stratus development over much of the central
and northwest portions of the state. Though forecast soundings
indicate ample boundary layer moisture, increased low level flow
will inhibit any fog development overnight.

Early Thursday, an embedded shortwave from the western CONUS
trough moves into eastern Montana. Weak isentropic lift over far
western North Dakota leads to slight precipitation chances
beginning Thursday morning. Thermal profiles suggest mostly a rain
snow mix with a possibility for sleet in the southwest where a
deeper warm nose and cold surface layer may lead to some
hydrometeor melting and refreezing.

.LONG TERM...(Thursday night through Wednesday)
Issued at 303 PM CDT Wed Mar 14 2018

Thursday night through Friday the Colorado low quickly closes off
over central Kansas/Nebraska, keeping greatest synoptic forcing
off to our south. Weak moisture transport over
southern/southwestern North Dakota will keep chances for snow/rain
in the forecast through Friday however accumulations will be

Global models are consistent with bringing another low out of the
Rockies on Sunday, moving east through the central Plains through
Monday. Consistency in placement of upper level low and
focus of precipiation is low however. Both the ECMWF and GFS bring
precipitation into central and Western North Dakota with the
Canadian keeping moisture to our south. At the time the consensus
of the ECMWF/GFS warrants a chance of rain or snow Sunday early
Tuesday. Precipitation amounts and timing will remain uncertain
until we get closer to the weekend.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 700 PM CDT Wed Mar 14 2018

Clear sky to start the TAF valid period with increasing mid cloud
into western North Dakota ahead of developing low pressure to the
southwest. As far as the east, enhanced short term guidance is
showing a moistening lower atmosphere. Model output has been
overdone of late with respect to this. Patchy fog is also possible
east, KBIS-KJMS, due to snow melt from Wednesday. Confidence is
not high enough at this point to prevail any MVFR / IFR the TAFs,
rather, introduced SCT lower cloud and a TEMPO period of MVFR
visibility in fog, again KBIS-KJMS. Note that pockets of -rasn are
expected after 15/18Z along the Montana border.




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