Area Forecast Discussion
Issued by NWS Grand Forks, ND

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000
FXUS63 KFGF 180546
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1146 PM CST Sat Feb 17 2018

.UPDATE...
Issued at 1144 PM CST Sat Feb 17 2018

No further changes. Updated aviation section.

UPDATE Issued at 1022 PM CST Sat Feb 17 2018

Much discussion on what to do with headlines. Discussed with
Duluth office resulted in an advisory across RRV and into NW/NC
MN. Overall the various, many short range models, indicate a
widespread 3-5 inch event in all but the far north and far south.
Somewhere in this area though will likely be an intense 30 mile
wide band of heavier snow that may well be into the warning range.
While confidence is high in the area of snow...it is quite a bit
lower in where the heaviest snow band will be. Felt it was best to
go with the advisory, instead of keeping a watch, then if needed
update a few areas where this band sets up. Frontogenetical
forcing is strongest in that Mayville-Ada-Bemidji zone. But some
short range models have waffled in this placement.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 350 PM CST Sat Feb 17 2018

Expect partly cloudy conditions with light northwest winds through
the evening with winds becoming light during the overnight.
However... a storm system is now moving out of western Montana
that should move quickly into the Dakotas overnight and overspread
northern Minnesota on Sunday.

Model guidance is still quite variable as far as total snowfall
and strength of the surface low. Consensus guidance would track
the surface low into southwest MN around 18z with heavier snow
ahead and north of the low, and strongest winds developing behind
the low.

Thus conditions should change markedly through the early morning
hours in eastern North Dakota as clouds thicken after midnight and
areas of light snow develop into central ND by 3am, then into and
across eastern ND from 3am through 6am. Strong north winds should
develop and spread across eastern ND by midmorning and persist
through much of the day. Though snowfall should end by early
afternoon there should be blowing and drifting snow persisting
into late afternoon.

Heavier snow is expected into the Red River Valley from mid
morning into noon... with north winds increasing throughout the
forenoon. Prolonged periods of low visibilities in blowing and
drifting snow are possible down the Valley corridor.

Heaviest snow is likely across northwest Minnesota from the
forenoon into mid afternoon... with snow tapering off from the
west by nightfall.

.LONG TERM...(Sunday night through Saturday)
Issued at 350 PM CST Sat Feb 17 2018

An active precipitation pattern sets up from Sunday through Tuesday
as an upper level trough builds over the western CONUS placing the
region under southwest flow aloft. Embedded shortwaves are expected
to propagate within the southwest flow providing dynamical support
to produce precipitation Monday and Tuesday. A zone of baroclinicity
will be set up south of the region oriented southwest to northeast
through the Central Plains into the Upper Midwest. An elongated area
of snow is expected to develop along this baroclinic zone from
around South Dakota into southern and central Minnesota for an
extended period, Monday through Tuesday. The northeastern edge of
this snow could impact the CWA with better chances residing in
southern and eastern counties. With generally light snow expected,
periodical upticks in snow may be expected with the passage of each
shortwave focusing its energy and lift. There is also some chance
for banding of snow as mid level frontogenesis will be possible over
eastern South Dakota into west-central Minnesota. One notable period
of snow will be Monday overnight with a shortwave progged to pass
through the region. As of now snow accumulations remain on the
lighter side, ie 1 to 4 inches, but confidence on these totals are
low as it will depend on location and timing of these embedded
shortwaves, not to mention the extent of dry air near the surface
filtering in from the north. Breezy winds generally out of the north
could bring some potential of patchy blowing and drifting snow
mainly for Monday afternoon. Temperatures will be on the cooler side
with highs generally into the single digits to teens above zero and
lows in the negative single digits.

As the western trough axis begins to move eastward on Wednesday,
conditions dry with help from a surface high pressure moving over
the region. Cold air aloft will allow for colder than normal
temperatures to return mid next week, although forecast 850 mb
temperatures warmer than -20 C should limit the magnitude of cold
expected. There is a chance of a brief warm up to near normal
temperatures late next week as the upper trough deamplifies and
breaks down. Precipitation chances from mid to late next week look
minimal at this time, although confidence on this is low.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1144 PM CST Sat Feb 17 2018

Conditions will be going downhill thru the early morning as vsbys
lower in snow. In most locations IFR vsbys are anticipated as
predominate 12z-18z period...then improving. Winds more east-
southeast turning north Sunday midday/aftn with some gusts over 25
kts in the RRV.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Winter Weather Advisory from 5 AM to 4 PM CST Sunday for NDZ008-
     016-027-030.

     Winter Weather Advisory from 3 AM to 3 PM CST Sunday for NDZ006-
     007-014-015-024-026-028-029-038-039-054.

MN...Winter Weather Advisory from 6 AM to 6 PM CST Sunday for MNZ005-
     006-008-009-013>017-022>024-027-028.

     Winter Weather Advisory from 5 AM to 4 PM CST Sunday for MNZ001-
     002-004-007.

     Winter Weather Advisory from 3 AM to 3 PM CST Sunday for MNZ003.

&&

$$

UPDATE...Riddle
SHORT TERM...Gust
LONG TERM...CJ
AVIATION...Riddle



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