Area Forecast Discussion
Issued by NWS Grand Forks, ND

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277
FXUS63 KFGF 260012
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
712 PM CDT Tue Apr 25 2017

.UPDATE...
Issued at 712 PM CDT Tue Apr 25 2017

Only minor adjustments to the grids, mainly to increase PoPs.
Although confidence is high that precipitation will occur, we are
still not within the predictability horizon for details such as
snow amounts or ice accumulation. Mid-upper level low will spread
deformation zone forcing into the southern FA through the
overnight hours. This feature will propagate very slowly, which
will prolong precipitation. Starting to think that QPF of at least
0.50 inch will be possible in a narrow area. Will continue to
monitor incoming CAM guidance to gain confidence in this trend.
Lots of things to consider such as the above freezing warm layer
aloft (mainly east of the valley), surface temperatures, ground
temperatures, how much snow can accumulate, etc. The potential is
increasing that the winter weather advisory may need to be
expanded in area to include the Fargo area and portions of SE ND
for mainly 3-5 inches of snow, with a mix of ice/snow to the
east/northeast of Fargo.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 315 PM CDT Tue Apr 25 2017

Very challenging forecast ahead through the short term. Surface
low/inverted trough associated with stronger wave/jet maxima will
lift through Iowa into southeast Mn into Wisconsin by morning.
NW edge of Deformation zone pcpn band to impact roughly the se
half of the fa tonight into Wednesday. Thermal profiles and
surface temperatures through this area will be critical on phase
and amounts. Warm layer aloft most noticeable over the eastern/SE
fa tonight however this area also has the warmest surface
temperatures. Over the past several days surface temperatures have
also been above freezing so the ground should be relatively warm.
This makes potential for freezing pcpn challenging. Warm layer
aloft does hold through 06z and if surface temperatures can cool
freezing rain likely to cause issues. Farther south and west more
uncertain for freezing rain so will have to be monitored. Column
continues to cool later tonight so should see an transition to a
wintry mix then snow. At this time snow amounts look to range in
the 1 to 3 inch range with locally higher amounts possible. At
this time favored f-gen forcing for banding snow looks to be to
our east. There is however some weaker f-gen forcing over the tri-
state border later tonight which could result in some higher snow
snow amounts but at this time too much uncertainty. Based on
icing potential and modest snow amounts will be issuing a winter
wx advisory for the eastern fa to include Bemidji, Park Rapids and
Bagley.

Snow within Deformation zone will continue across this area
tomorrow and will have to continue to monitor for additional snow
amounts. Temperatures again tomorrow will go nowhere holding a
few degrees either side of freezing.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 315 PM CDT Tue Apr 25 2017

The primary challenge for the long term period will be the outgoing
low pressure system primarily impacting the short term period.  A
constant fetch of gulf moisture into this system will keep wrap
around precip in the forecast from Wednesday night through about
midnight Friday morning.  The GFS does show a break early Thu
morning with some very light QPF developing again Thu aftn...which
could be more drizzle considering the drying in the mid layer.
Precip types will be dependent on sfc temps but the soundings appear
a bit cooler than the blended hourly temps for Thu, and need to
watch potential for some drizzle in the aftn hours.  Primary
impacts, however, will be Wed PM in the 00Z to 06Z Thu timeframe
where an additional half an inch of snowfall may occur as the short
term period system winds down.

Dry weather then expected by early Fri morning through the weekend.
Weekend highs will climb into the 50s pending significant cloud
cover...but a sfc ridge extending from a Canadian high will keep dry
weather until at least Mon aftn, when a sfc low over MT begins
developing light rain over the central Dakotas which will most
likely move into ern ND early Tue morning.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 712 PM CDT Tue Apr 25 2017

Most sites already MVFR...and most sites should stay this way
through the evening hours. Precipitation expected to develop later
this evening across the KFAR and KBJI area. KFAR should be mostly
snow...while KBJI will be a mix before turning to snow. Cigs/Vsby
will drop to at least IFR where precipitation occurs.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...Winter Weather Advisory until 7 PM CDT Wednesday for MNZ009-016-
     017-023-024.

&&

$$

UPDATE...TG
SHORT TERM...Voelker
LONG TERM...Speicher
AVIATION...TG



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