Area Forecast Discussion
Issued by NWS Bismarck, ND

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973
FXUS63 KBIS 152144
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
344 PM CST Sun Jan 15 2017

.SHORT TERM...(This evening through Monday)

Issued at 344 PM CST Sun Jan 15 2017

Temperatures will again be the main forecast challenge and
highlight in the short term period.

Currently, quasi-zonal flow aloft with a surface high pressure
ridge off to our south. Southwesterly low level winds vary in
strength across west and central North Dakota depending on the
elevation. Higher areas seeing stronger winds and low lying areas
nearly calm. Temperatures are greatly dependent on these winds,
warmer where mixing is stronger and colder where winds are having
a hard time increasing in the valleys. Our morning ROAB here at
KBIS at 5am CST showed a massive low level inversion, -10F at the
surface and +32F 900FT up! Very common in the winter when there
is a deep snow pack and mid level WAA.

Surface ridge moves slowly south and east tonight with a subtle
surface trough moving through the Northern Plains ahead of a
northern stream upper level S/WV trough. Models are indicating
increasing boundary layer moisture along to ahead of the upper
trough into west central and southwestern ND overnight towards
12Z, then continuing to expand east and slightly south during the
day Monday. It appears this is plausible as there are low clouds
now associated with this upper level wave which is currently over
the Idaho panhandle and northwestern MT. As a result increased sky
cover late tonight through much of the day Monday. Am concerned
there is potential for freezing drizzle as the low clouds develop,
with dry air above the expected stratus coupled with forcing with
the wave and sfc temperatures in the 20s. For now I left any
freezing precipitation mention out of the forecast as still
uncertain where and how much low stratus will develop. Will
monitor closely and update accordingly.

Temperatures will again be a problem for Monday due to the same
reasons as the last couple days. About as much mixing tomorrow as
we are seeing today. I thus lowered forecast highs a few degrees
based on what we observed today and yesterday for those areas that
have been colder than forecast.


.LONG TERM...(Monday night through Sunday)

Issued at 344 PM CST Sun Jan 15 2017

Moderating temperatures and dry conditions through the middle of
next week, followed by what looks like an increasingly active
weather pattern along with colder temperatures late this week and
through next weekend continue to highlight the extended forecast.

Broad ridging develops Tuesday-Wednesday maintaining dry
conditions and allowing mild Pacific air to surge westward into
the Northern Plains. Robust WAA Tuesday-Thursday along with models
suggesting a good mixing potential should bring a nice warming
trend to west and central ND. Forecast high temperatures remain in
the 30s to low 40s by Wed/Thu.

Both the GFS and EC continue to depict a long wave trough moving
into the western CONUS Thursday, moving and amplifying the ridge
east resulting in strong southwest flow aloft developing.
Uncertainty remains high on any details with model spreads
remaining large, though it is safe to say it will be more active
regarding precipitation chances and trending colder later this
week and into the weekend. Currently the forecast calls for
rain/snow Friday & Saturday, and there may also be some ice
potential. Again, very uncertain. Both the GFS/EC bring in another
long wave trough late in the period which will continue to keep
our pattern active well into next week.


&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)

Issued at 100 PM CST Sun Jan 15 2017

VFR conditions and a west to southwest flow expected at all TAF
sites through the 18Z TAF period. A weak cold front will move
through the forecast area late tonight through Monday morning. This
will bring more of a northwest flow and increasing moisture to the
west Monday morning. Models are indicating some low level moisture
especially at KDIK Monday morning. At this time will keep KDIK at
low vfr as models as the low level moisture is quite shallow.


&&

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

&&

$$

SHORT TERM...NH
LONG TERM...NH
AVIATION...TWH



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