Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 271858
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1258 PM CST Mon Feb 27 2017

.UPDATE...
Issued at 1247 PM CST Mon Feb 27 2017

Relatively narrow band of snow to the north of a sw-ne surface
boundary from DVL to far northern valley will continue to lift ne
through the afternoon. While there is some f-gen forcing,
precipitable h2o values only around two tenths of an inch and
model guidance indicating that isentropic lift weakens mid-late
afternoon. Local web cams indicating some accumulations but
nothing too serious. Still thinking and inch maybe two in snow
band. Increased pops and snow amounts in snow band otherwise no
other forecast changes.


UPDATE Issued at 924 AM CST Mon Feb 27 2017

Flurries or very light snow is into the far nw counties so nudged
pops into this area a little earlier but no big deal as far as
forecast differences.  No other changes.

UPDATE Issued at 640 AM CST Mon Feb 27 2017

Made a few tweaks to cloud cover, but otherwise no major changes
to the forecast this morning.

&&

.SHORT TERM...(Today and tonight)
Issued at 345 AM CST Mon Feb 27 2017

Snow chances and amounts throughout the period will be the main
challenge.

Water vapor loop shows fast westerly flow aloft starting to
becoming southwesterly, with several weak embedded shortwaves
upstream. One such shortwave is already in eastern MT and will
move out into northern ND during the day today. In addition to the
upper support provided by the shortwave, the models indicate some
decent 850mb frontogenesis coming in this afternoon and evening.
Although it does not totally coincide with the best upper level Q
vector convergence. Still, it should be enough to generate some
light snow starting in the Devils Lake Basin this afternoon and
spreading north and eastward into the early evening. The models
all show variations of this band of precip, with slightly
different placement and QPF all very light. Think that amounts
should be fairly light and kept snow totals below an inch.

This first round of snow will be winding down as another stronger
shortwave trough will be approaching along the ND/SD border later
today and into tonight. The main surface low will be well to our
south, but an inverted trough will be sticking up into the
southeastern counties, with a strong baroclinic zone developing.
Frontogenesis at 700mb will be better correlated with upper
support and there will be better moisture available across the
south. The models break out up to a few tenths of an inch of QPF
across the southeast tonight into Tuesday morning, which seems
reasonable at this point. Will continue to keep high POPs in our
southeast with amounts of 1-2 inches possible and will keep an eye
in case they need to be bumped up more.

As for temperatures, warmer air will begin to push into the far
southern counties today, which will help temps rise into the upper
30s to near 40, while the northwest will remain firmly entrenched
in the cold and stay in the teens. The large temperature range
will continue into tonight with clearing skies and more snow
keeping the north near the zero mark while clouds precip have the
south staying in the 20s. Colder air will start moving back south
on Tuesday as the surface trough finally pushes off to the east.

.LONG TERM...(Tuesday night through Sunday)
Issued at 345 AM CST Mon Feb 27 2017

Tuesday night through Wednesday night...The next significant
shortwave trough will begin to move into the northern Plains as
flow starts to transition to a more northwesterly direction. All
the models have some QPF with this shortwave although again
amounts will be very light. Will continue to keep our 20-30 POPs.
The next reinforcing shortwave will dig down Wednesday night, with
the surface low tracking from the western Dakotas into southern
MN. The best QPF will be with the baroclinic zone to our south and
west, but the southeastern ND counties could get clipped with a
bit of snow. Temperatures will be on a downward trend as we head
into mid-week.

Thursday to Sunday night...The end of this week will feature an
overall dry period with low snow chances each day somewhere in the
forecast area. Thursday will see the light snow chances across the
southeastern ND as a clipper moves through central ND.  Then as
500mb flow transitions from NW to zonal flow some light snow
chances are possible across the north within the WAA regime Friday.
A short wave is expected to move across southern Canada Saturday and
with it there is the possibility of some light precipitation
brushing the northern areas. Temperatures will be coldest on
Thursday with teens to the north and mid 20s south. Warmer air
returns on south winds on Friday and into Saturday as temps rise
into the low 30s north to low 40s south.

By Sunday there is a stronger signal for larger scale system to
impact the region with a more robust 500mb wave moving into the
Northern Rockies. As the track of the SFC low pressure emerges the
the best chances for snow across the central and northern plains for
Sunday and Monday will be refined.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1247 PM CST Mon Feb 27 2017

VFR conditions expected into tonight over all but the DVL site
where snow band bringing MVFR cigs/vsby. Later tonight and Tuesday
am potential exists for lower cigs/vsby (MVFR) from FAR-BJI as
next snow band develops. Models continue to differ in solutions
on where and when main band will develop so confidence not high at
this point.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&

$$

UPDATE...Voelker
SHORT TERM...JR
LONG TERM...JR/JK
AVIATION...Voelker



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