Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 251751

Area Forecast Discussion
National Weather Service Bismarck ND
1151 AM CST Sat Feb 25 2017

Issued at 1146 AM CST Sat Feb 25 2017

The initial shortwave early this morning which produced one half
inch here at the Bismarck weather office continues to slide into
the southern James River Valley. Will keep likely/categorical pops
here for the early part of the afternoon.

Main update was to increase POPS to categorical - northwest North
Dakota this afternoon, then across the north central this evening
and early tonight. Latest water vapor imagery shows our next
shortwave now over southeast Saskatchewan. Both the NAM/GFS show
this as a stronger wave with frontogenetical forcing aligning
with synoptic scale ascent this afternoon and evening, along with
mid level lapse rates around 6.5C/km. Used a blend of the HiRes
models and the NAM/GFS for POPs and snowfall/qpf output. Expecting
a 1 to 3 inch snowfall range northwest North Dakota southeast
into the northern James River Valley, where forcing is maximized.
Will re-evaluate for potential higher amounts associated with
banded snow this evening, as the GFS shows a 70kt upper jet coming
over the top possibly resulting in a stronger/deeper circulation,
and hence banded snow.

UPDATE Issued at 844 AM CST Sat Feb 25 2017

A band of light snow continues to gradually sag south primarily
over south central into parts of southwest North Dakota. For mid-
morning update main change was to significantly increase
precipitation chances with this, though do not expect much in the
way of accumulation. This band will continue to track on its way
to the south-southeast, with the next round of light snow pushing
into the area later today as a fast moving shortwave over Montana
slides into the area. Have also expanded patchy fog coverage for
a little longer and a bit further south as some webcams are
showing reduced visibilities.

UPDATE Issued at 619 AM CST Sat Feb 25 2017

Added some patchy fog across the northwest this morning otherwise
current forecast looks good.


.SHORT TERM...(Today and tonight)
Issued at 324 AM CST Sat Feb 25 2017

With the h500 flow from the northwest and several weak shortwaves
expected to move through the northern plains today and tonight
will see an active weather pattern for light snow. The first weak
system and associated cold front is currently moving through
central North Dakota bringing a band of light snow along with it.
This area not expected to produce more than a half an inch for
the most part through noon today.

A little more robust system will follow tonight into Sunday
morning. This has the potential to spread an inch or two across
central North Dakota tonight. For the most part accepted the
CONSHORT guidance for the forecast but raised the winds across the
James River Valley late tonight where the departing low and
advancing high produce 3 to 4 mb pressure rises in 3 hours. If
there were more fresh snow on the ground would add blowing snow
however with the recent warm weather not much to blow around for
this area and new snow not enough either.

.LONG TERM...(Sunday through Friday)
Issued at 324 AM CST Sat Feb 25 2017

For the extended period a quasi-stationary h500 trough will remain
over the central CONUS through Wednesday. Within this trough
several shortwaves will roll through the region but none of these
impulses should cause significant snow but will have some chances
off and on. Temperatures will remain near or a bit below normal
until the end of the week. By then the h500 trough moves east and
a strengthening mid level west to northwest flow should bring a
chinook flow to portions of the high plains. Some warming will
likely reach far western North Dakota with highs possibly reaching
the 40s across the southwest Friday.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1118 AM CST Sat Feb 25 2017

Widespread MVFR cigs will continue over much of the area today
into tonight, with areas of IFR visibility developing,
particularly north, as the next round of snow pushes in later
today into this evening. Conditions will gradually imrove Sunday
morning, with most locations returning to VFR.




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