FXUS63 KBIS 190614

Area Forecast Discussion
National Weather Service Bismarck ND
114 AM CDT Mon Mar 19 2018

Issued at 114 AM CDT Mon Mar 19 2018

Changes with this update cycle were focused on increasing hourly
PoPs to 100 percent overnight over southwest and much of central
ND based on ongoing trends in snow, and to reduce them over far
northwest and north central ND. In the latter areas, relatively
drier northerly low-level flow is impeding the progress of snow
north of Highway 2 to this point, and in fact very recent radar
imagery suggests northward movement may have halted altogether at
the moment. For now, we maintained the idea of higher PoPs
spreading to the Canadian border by daybreak as larger-scale
synoptic ascent moves into central ND, but trends will require
monitoring the next few hours.

Otherwise, the forecast and headlines are on track. We received
several reports of 4 to 6 inches of snow in a band arcing from
near Marmarth to Fairfield to Garrison, and it's very plausible
some locations in that band will end up with around 7 inches when
all is said and done. However, frontogenetical forcing is already
waning per RAP-based analyses, and the body of model guidance
concurs that downward trend will continue overnight, allowing the
snowfall to become less banded in nature, and thus lighter. The
steep mid-level lapse rates sampled by the 00 UTC Bismarck RAOB,
which were on the order of 7.5 C/km in the 3-6 km AGL layer, are
also likely being slowly reduced and that also heralds a lower
risk of enhanced snowfall rates going forward. Add in the fact
that winds are light with this event, thus making impacts rather
similar for a 4 versus 7 inch snowfall, and we chose to hold off
on upgrading any counties to Winter Storm Warnings.

Issued at 953 PM CDT Sun Mar 18 2018

I opted to expand the winter weather advisory to include more
central counties. Models fairly uniform with wrapping moisture
back eastward across more of my central counties tonight/Monday
AM. Also already have picked up 2-3 inches of snow east of
Bismarck due to a persistent band of precipitation across eastern
Burleigh/Kidder/northern Stutsman counties this evening, which is
finally showing signs of dissipating/moving more east. Another
factor is current wet roads from Bismarck east will likely freeze
making for hazardous travel later tonight and during the Monday
morning commute.

Issued at 634 PM CDT Sun Mar 18 2018

No major changes with this forecast package. Headlines remain
valid. POPs were adjusted the most to account for latest radar
imagery, specifically the band of precipitation lifting north
across my central counties. Otherwise radar is filling in
southwest as snow develops northward, which the inherited forecast
has well depicted.


.SHORT TERM...(This evening through Monday)
Issued at 246 PM CDT Sun Mar 18 2018

The Winter Weather Advisory appears on target for tonight through
tomorrow morning. Light snow/freezing drizzle continues to develop
across southwest North Dakota this afternoon. Freezing drizzle
will give way to all snow by later this evening.

The consensus among forecast models is to focus the highest snow
amounts across western and north central North Dakota. The latest
trends shift the heaviest axis a bit further west and place it
between Beach and Glen Ullin. Three to five inches of snow, with
isolated six inches seem likely across the Advisory area.

Heaviest snow amounts are expected between 6 pm and midnight
across western North Dakota, and midnight and 6 am across north
central North Dakota.

.LONG TERM...(Monday night through Sunday)
Issued at 246 PM CDT Sun Mar 18 2018

Light snow is possible Tuesday with the passing of a quick upper
level wave. Wednesday and Thursday look dry and milder with a
ridge building in over the central US. Highs are expected to
reach into the lower 40s southwest and 30s elsewhere.

By the end of the week into the weekend, a large and potent
negatively tilted upper low over the northwest US will send some
shortwave energy into the Northern Plains. Current trends suggest
another opportunity for accumulating snow Friday through Sunday.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 114 AM CDT Mon Mar 19 2018

Widespread IFR and occasional LIFR conditions in snow will
continue across most of western and central ND through Monday
morning. Conditions will slowly improve as snow ends in western ND
Monday morning, and over central ND during the afternoon. However,
based on recent model guidance, MVFR or IFR stratus will likely
persist through the 06 UTC TAF cycle in most locations.


Winter Weather Advisory until 1 PM CDT /noon MDT/ this afternoon
for NDZ010>012-017>023-025-031>037-040>046.



Back to Main Forecast Discussion Page