Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 141130
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
530 AM CST Tue Nov 14 2017

.UPDATE...
Issued at 445 AM CST Tue Nov 14 2017

Visibilities across the extreme northern Red River valley have
improved. However, the dense fog advecting northward has reached
the northern edge of the dense fog advisory, and expanded this
slightly north of the current advisory.

&&

.SHORT TERM...(Today and Wednesday)
Issued at 303 AM CST Tue Nov 14 2017

Dense fog will be the initial concern. The dense fog advisory from
earlier (northern Red River Valley) is still valid with
observations remaining 1/4sm or less. The other area of concern is
the low level moisture advecting northward into the FA. This has
led to visibilities dropping through the night. 1/4sm visibility
has developed across eastern South Dakota and adjacent portions of
Minnesota, which is also advecting northward. Some of the model
guidance actually has a decent handle on the situation, and
indicates this trend to continue. Timed the dense fog northward
until sunrise and went with this area for a dense fog advisory.
There are some sites that are not yet dense, but figured it would
be best to get ahead of the game. Most road sfc temperatures are
above freezing, or rising, so do not any additional impacts from
freezing mist on roadways.

Thinking clouds/fog will move into much of the FA by mid-
afternoon before the SFC trough pushes the low level moisture
east. As the SFC trough interacts with the low level moisture,
forcing may be enough for patchy drizzle to develop this evening.
Otherwise, best precip chances will be late tonight into early
Wednesday across NW MN with the passage of a stronger upper level
wave. This precip should be all snow, with amounts remaining very
light. High pressure builds into the region by later Wednesday
afternoon.

.LONG TERM...(Thursday through Monday)
Issued at 357 AM CST Tue Nov 14 2017

Upper level ridge over the western Dakotas will shift east over the
area Wed night. Another upper level trough will move across southern
Canada Thu night with the GFS a faster solution than most of the
models. Warm advection precip is forecast for Thu night into Fri.
Also the right entrance region of the jet will be over the area.
Precip is expected to be light.

Main upper trough over the northeast Pacific will move through the
Northern Plains Fri night. The GFS remains the faster model and
farther south than the ECMWF. The ECMWF was trending a little slower
while the GFS was trending faster and farther north except for the
latest run. Precipitation also is expected to remain light. The
ECMWF and the GFS were 180 degrees out of phase by Mon.

The long wave pattern amplifies through the extended period with an
upper level ridge over the Rockies and a long wave trough over
eastern North America.

High temperatures were generally increased zero to two degrees for
Fri. High temps were increased one to three degree for Sat, and
increased five degrees for Sun and Mon from yesterdays forecast.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 530 AM CST Tue Nov 14 2017

Low clouds and fog continue to move northward. LIFR conditions
will affect locations within and east of the Red River Valley
through at least the morning hours. Not sure if conditions will
improve this afternoon. Thinking at least some improvement to at
least IFR/MVFR, but that might not happen. Best bet for
improvement will be tonight or Wednesday morning, although with a
cold front moving through the region there might not be much
actual improvement.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Dense Fog Advisory until 10 AM CST this morning for NDZ027-029-
     030-038-039-049-052-053.

MN...Dense Fog Advisory until 10 AM CST this morning for MNZ001>003-
     007-008-013>017-022>024-027>032-040.

&&

$$

UPDATE...TG
SHORT TERM...TG
LONG TERM...JH
AVIATION...TG



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