Area Forecast Discussion
Issued by NWS Grand Forks, ND

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130
FXUS63 KFGF 220001
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
701 PM CDT Sat Oct 21 2017

.UPDATE...
Issued at 700 PM CDT Sat Oct 21 2017

Upper level trough over the area will continue to move north and
east tonight. Radar indicated light showers mainly over north
central MN and were moving north at 50-55 knots. Little change to
current forecast. Tweaked pops to match current radar.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 322 PM CDT Sat Oct 21 2017

Precip chances will be the main issue for the period.

Water vapor loop shows the main trough axis still just entering
the Western Plains, but a lead shortwave is currently lifting
through eastern ND out ahead of that main system. A line of
showers has developed with that shortwave, extending from the
Devils Lake Basin into the central Red River Valley and west
central Minnesota. None of the CAMs are doing a very good job with
these showers, and a few cells have grown strong enough across the
MN counties to produce some thunder. Think the showers will
continue to lift northeastward through the next few hours, while
another band of light rain with the main trough axis moves only
slowly east from central ND. Stronger convection will stay to the
south where there is actually some instability. Think the precip
across all but the far eastern CWA will dissipate quickly late
this afternoon as we lose heating and the lead shortwave rotates
out of the area.

Tonight, skies will clear off as the cold front pushes the rest of
the way across the region. West to southwest winds will keep us
mixed, so even with good radiating out temps should stay in the
30s to low 40s. Southwesterly winds will continue into tomorrow,
and it looks like there will be some warm air advection. Even with
a cold start and increasing clouds, think Sunday should get into
the upper 50s into the 60s. The next strong shortwave will be
approaching the Saskatchewan/Manitoba border during the day, which
should increase clouds and bring a slight chance for some rain
along our northwestern border late in the day.

.LONG TERM...(Sunday night through Saturday)
Issued at 322 PM CDT Sat Oct 21 2017

A cooling trend is in store for the upcoming work week. Monday will
see scattered rain chances return for areas north of the Highway 2
corridor as a shortwave trough progresses through the northern
portions of the region. Temperatures for Monday are expected to be
close to seasonal with highs in the mid upper 50s and overnight lows
dropping to the mid to low 30s. Tuesday will see drier conditions
with temperatures similar to Monday.

Most guidance suggests a shift to a more active pattern beginning
mid week. There is reasonably good agreement that a weak cold
front/surface trough will progress through northwest Minnesota
region late Tuesday night into Wednesday. This could lead to a few
scattered showers overnight Wednesday. Temperatures are expected to
be the warmest on Wednesday with highs reaching to the mid to upper
50s in southeastern North Dakota and through the Red River Valley
with mid 50s likely in northeastern North Dakota and northwestern
Minnesota.

Beginning Thursday model guidance begins to show more spread...both
between models and sequential model runs... especially with regards
to timing. However... an overall signal persists that rain chances
will increase Thursday into the weekend. Both the GFS and ECMWF show
large scale troughs deepening over the western U.S. with the 12z GFS
having a more amplified and robust wave ejecting out over the
plains Thursday into Friday. Meanwhile, the ECMWF suggests less
amplified wave ejecting over the northern Plains during the same
Thursday to Friday time frame. Notable timing differences between
runs of the ECMWF place slightly more confidence on recent GFS
runs.

Regardless... both solutions show precipitation chances in the
northwest deformation zone of surface lows that track over the north
central Plains and into the Great Lakes region. With overnight
temperatures dropping below freezing and cold air in place aloft a
wintry mix of snow and rain can not be ruled out during the
overnight hours Thursday through Saturday... especially along the
Canadian border and into northwestern Minnesota. Highs Thursday
through Saturday are expected to remain above freezing in the low to
mid 40s. Even with day time temperatures above freezing impacts from
any winter precipitation are difficult to determine at this time due
to high model uncertainty in timing, precipitation location, and
precipitation amount. This system will need to be monitored for
potential impacts heading into the upcoming work week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 700 PM CDT Sat Oct 21 2017

MVFR conditions were located over the far eastern zones roughly
east of a line from FGN to west of PKD. Expect MVFR cigs to move
to the north and east by midnight. Elsewhere a mostly cloudy sky
was over the region with cigs from 40 to 85 hundred ft. Satellite
indicated cloud decks at two different levels moving in two
directions. Cloud deck to the west was moving southeast around 35
knots while cloud deck over the area was moving north at 50-55
knots. Cloud deck to the west was lower with cigs between 30-55
hundred ft. Clouds will clear over the southwest half of the area
by 12Z Sun.

&&

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

$$

UPDATE...JH
SHORT TERM...JR
LONG TERM...AM
AVIATION...JH



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