Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 141731

Area Forecast Discussion
National Weather Service Bismarck ND
1231 PM CDT Wed Mar 14 2018

Issued at 1224 PM CDT Wed Mar 14 2018

Observation sites in the northwest are reporting consistent
visibilities in the 4 to 7 mile range so we cancelled the Dense
Fog Advisory with this update. Fog in low lying areas and river
valleys is still plainly visible on satellite, especially in the
Missouri River valley west of Williston, so we kept some fog in
the grids. Otherwise no other major updates with this update.

UPDATE Issued at 1032 AM CDT Wed Mar 14 2018

We extended the dense fog advisory until 18Z given the persistence
of fog observed on the GOES-East Day Snow-Fog RGB product.

UPDATE Issued at 937 AM CDT Wed Mar 14 2018

Dense fog continues across northwest ND. No changes to the current
Dense Fog advisory. Updated sensible weather elements and
interpolated to mid-morning values.

UPDATE Issued at 632 AM CDT Wed Mar 14 2018

Dense fog migrating across northwest North Dakota, originally
mainly in the river valleys but now becoming more widespread. Will
issue a dense fog advisory through 16z.


.SHORT TERM...(Today and tonight)
Issued at 343 AM CDT Wed Mar 14 2018

Morning fog and high temperatures today are the main focus in the
short term period.

Currently, a large upper level low/trough was off the west coast,
with an amplified upper level ridge over the Rockies and Front
Range, resulting in northerly flow over the Northern Plains. An
upper level shortwave was diving south out of the Hudson Bay area,
with a surface cold front over northern Saskatchewan and
northwestern Ontario moving south.

Fog had developed over northwestern and north central North Dakota,
with some locales indicating dense fog with visibilities 1/4 mile or
less. Expect fog to continue developing during the morning hours,
likely including the higher elevations along the Missouri Coteau.
Have addressed this with a special weather statement rather than
issuing a dense fog advisory.

Today the aforementioned Canadian cold front is forecast to enter
northeastern North Dakota, moving southwestward into north central
and the James Valley later today. Meanwhile the west coast
low/trough moves onshore, nudging the upstream upper level ridge
into the western Dakotas. This will result in continued warm
advection over western North Dakota.

Looking at highs today in the low to mid 30s north through the James
Valley, with temperatures again reaching into the lower and mid 40s
over parts of southwestern North Dakota.

Tonight a potent shortwave ejecting from the base of the advancing
western trough reaches the central plains near
Colorado/Nebraska/Kansas. This will result in a southerly flow aloft
over the plains reaching well into Canada. A lee side surface low
develops over eastern Colorado, and an increasing southeasterly
surface flow develops this afternoon and continues tonight over
western and south central North Dakota.

The cold air associated with the Canadian high in northeastern North
Dakota and the warm air associated with the Colorado low pressure
system in southwestern North Dakota will result in lows tonight
ranging from around 10 above in the Turtle Mountains to the lower
20s in the far southwest.

.LONG TERM...(Thursday through Tuesday)
Issued at 343 AM CDT Wed Mar 14 2018

Thursday through Friday the upper level shortwave over Colorado
develops/moves east/northeast into the mid-Mississippi Valley,
bringing a large area of precipitation to the southern and central
plains, and into the Dakotas and eastern Montana. Temperature
profiles suggest a wintry mix of rain, snow, freezing rain and
freezing drizzle for western North Dakota. The greatest forcing will
remain south of our area, with only light amounts of precipitation.

Global models are consistent with bringing another low out of the
Rockies on Sunday, moving east across the central US through
Tuesday. There is high uncertainty about its track and how much
precipitation will make it into our area. The consensus of the
models warrants mentioning a chance of rain or snow Sunday through
Monday night for western and central North Dakota.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1224 PM CDT Wed Mar 14 2018

Lingering MVFR visibility to begin the 18Z TAF period at KISN is
expected to improve to VFR shortly. Otherwise VFR conditions
expected today and into this evening. By late evening and into the
overnight hours an increasing easterly flow is expected to develop
with mesoscale models and BUFKIT soundings indicating a moistening
lower atmosphere. Thus we have brought MVFR to IFR ceilings from
northeast to southwest into the forecast area tonight and lingering
through the morning on Thursday.




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