Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 161726

Area Forecast Discussion
National Weather Service Bismarck ND
1226 PM CDT Fri Mar 16 2018

Issued at 1203 PM CDT Fri Mar 16 2018

A band of moderate snow was located over western South Dakota
moving northwest under the influence of a 300 mb right entrance
region. The majority of this forcing continues to scrape our far
southwest with light radar returns moving towards
Bowman/Slope/Adams counties. Upstream road cameras in South Dakota
showing snowy conditions and a 2 inch snow report in Hoover, SD
this morning was enough to adjust PoPs so they increase earlier in
the day. Still expecting highest snow totals to be found in our
far southwest in the 1-2 inch range through this evening.

UPDATE Issued at 850 AM CDT Fri Mar 16 2018

Updated surface winds for this afternoon as southeast winds
increase with a tightening pressure gradient. Forecast soundings
are showing 10-15 kts carried down to the surface this afternoon
in the south-central. Otherwise updated going forecast with
current trends.

UPDATE Issued at 625 AM CDT Fri Mar 16 2018

Current forecast looks good. No changes.


.SHORT TERM...(Today and tonight)
Issued at 304 AM CDT Fri Mar 16 2018

The concern in the short term will be snow amounts across
southwest North Dakota. The southwest will just see a brushing of
snow as an upper low closes off south of the region causing a
pivot in the precipitation area. The dominant high pressure over
eastern North Dakota will keep the region dry for all but the far
southwest. Consensus snow amounts today and tonight across the
southwest will be up to 2 inches. Skies will be cloudy southwest
and partly to mostly sunny north and east.

.LONG TERM...(Saturday through Thursday)
Issued at 304 AM CDT Fri Mar 16 2018

The level of uncertainty in the long term continues to be high.
Model QPF differences and low level temperature profiles make the
weather type, and the eventual snow amounts and potential ice
accumulations, very uncertain for the Sunday through Monday

First, Saturday will see warmer temperatures as the consensus
among models suggests the an upper low across the central plains
will depart, to be replaced with a building h500 ridge over the
northern plains. This ridge forms in response to a three headed
h500 low over the northwest US. The fact this system is dispersed
over the northwest will lead to a spread in the model solutions as
the upper low breaks down and sends a split flow across the
northern plains Sunday into Monday. The more intense portion of
upper low will remain south of the region, which leaves the
northern plains in weak flow aloft dominated by the northern
stream upper low across southern Canada. The spread in model
solutions will impact the weather type as the GFS, the colder
solution, suggests a mix of rain and snow transitioning to all
snow. The SREF precip type suggests more widespread freezing rain,
with the Superblend input resulting also in freezing rain, due
primarily to a lack of ice crystals impacting natural cloud
seeding. Bufkit soundings analysis pegs the mid levels more
saturated than the Superblend depicted so initialized the ProbIce
with the GFS. This gave a more realistic weather type, still a
wintry mix of rain and snow and freezing rain but was judged a
better transition from the wintry mix to snow. Lastly the QPF also
contains significant uncertainty. If the southern system becomes
more dominant and remains further south the higher QPFs suggested
by the GFS may be overdone. So smoothed the QPF with an average of
the GFS and the Superblend. This still leads to fairly high
uncertainty in the the snow fall amounts.

Tuesday through Thursday will become milder owing to a broad
ridge over the northern plains. By Friday rain and snow are
possible with the approach of a shortwave trough in southwest flow


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1222 PM CDT Fri Mar 16 2018

Generally VFR conditions are expected to prevail through the TAF
period, however, a period of MVFR CIGS are anticipated from 06-12z
at KISN/KDIK. Fog is possible at KJMS late tonight and into the
early morning hours. There is still some uncertainty as to how
widespread and dense fog developement will be over the James
Valley. At this time only went briefly into MFVR with the KJMS
TAF for fog.




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