Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 171725
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1125 AM CST Sun Dec 17 2017

.UPDATE...
Issued at 940 AM CST Sun Dec 17 2017

Water vapor imagery continues to show two features propagating
across Canada that will affect our weather over the next couple of
days. The first wave across southern Manitoba will have little
influence as the stronger wave across western Canada will have
greater influence increasing low level southerly return flow. As
such, sky/fog forecast is difficult with warming temps
counteracted by increasing low level moisture. For now, continued
optimistic that low level clouds will continue to clear from west
to east as low level temps warm. Did continue fog in the forecast
until around noon with isolated webcams/observations still
indicating 1/2sm or less visibility. Otherwise, forecast is on
track. Will need to consider fog again tonight for a portion of
the region.

&&

.SHORT TERM...(Today and tonight)
Issued at 346 AM CST Sun Dec 17 2017

An upper level wave is moving across southern MB this morning. South
to southwesterly winds exist across the forecast area this
morning...with a high over southeastern Ontario and a low over far
NW Canada. This low will make its way eastward as an upper level
wave moves out of the Gulf of Alaska. The southern extent of this
upper wave will brush the northern zones, likely bringing some light
snow to the area on Monday.

Currently, dense fog exists across parts of the south including
Detroit Lakes, Fergus Falls, and Elbow Lake areas. Recent call from
Richland Law Enforcement confirms dense fog in the southern part of
that county as well. Latest LAV guidance has fog in this area
through late morning. Currently have Dense Fog Adv through noon.

We should see some sunshine in most areas today. Believe the far SE
will eventually break out of the clouds as well, but it might be
late in the day. It should be a rather nice day as highs will be
in the upper 20s to 30s with relatively light winds and some sun.
Tonight, the south to southwesterly winds will stay up a bit...
limiting fog potential. However, the LAV guidance tries to bring
some fog in again to the Fergus Falls area and other parts of the
southeast. Believe this is overdone.

Monday and Monday night`s upper wave may bring a dusting of fresh
snow to the far north. Don`t expect much more than an inch, however.
Monday does look like the warmest day for quite a while with highs
in the 30s and westerly winds.

.LONG TERM...(Monday through Saturday)
Issued at 346 AM CST Sun Dec 17 2017

Tuesday... A cold front will bring windy conditions and colder
temperatures. Winds aloft remain strong in model guidance but mixing
potential still looks limited so breezy but not high impact winds
expected.

Wednesday... Models continue to be in agreement that a warm air
advection snowfall event will occur in the Northern Plains.  The
entire forecast area in eastern North Dakota and northwest Minnesota
is in the risk area but the differences in deterministic and
ensemble guidance are still significant enough that the exact
locations and amounts are still uncertain. Another concern is that
banding is possible due to mid level frontogenesis leading to much
higher snowfall amounts in some areas. Model forecast QPF with
expected snow ratios provide the potential for a significant, but
uncertain snowfall event.

Thursday to Sunday... Some of the coldest air so far this season
will move in to eastern North Dakota and northwest Minnesota. Based
on CPC 6-10 day and 8-14 day temperature outlooks the colder air
will remain with us for a while.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1125 AM CST Sun Dec 17 2017

Sites along and west of the Red River Valley expected to remain
VFR through much of the period. Snow showers and reduced
visibility possible later Monday afternoon for the sites closer to
the International border. East of the valley, forecast is very
uncertain. Latest guidance suggests VFR conditions this afternoon
becoming LIFR/IFR/MVFR again this evening into the overnight
hours. Went with an idea similar to this as it makes sense given
the weather set-up, but details such as timing and exactly how low
conditions become are still up in the air.

&&

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

$$

UPDATE...TG
SHORT TERM...Knutsvig
LONG TERM...NC
AVIATION...TG


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