Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 182103
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
303 PM CST Sat Feb 18 2017

.SHORT TERM...(This evening through Sunday)
Issued at 303 PM CST Sat Feb 18 2017

Any fog formation overnight and temperatures tomorrow will be the
main challenges for the period.

Temperatures warmed quite nicely and will continue to do so over
the east, but some clouds moving into the west have slowed down
the climb. Readings are still unseasonably mild and snow continues
to melt and release moisture into the boundary layer. The weak
surface high currently over the western CWA will move east
tonight, and there will be a period of light and variable winds
before winds pick up from the east later tonight. However, there
will continue to be some clouds moving into the area from the
west as the surface trough develops to our west. Think the cloud
deck will keep us from completely radiating out and fog from
forming. The MOS guidance leans in this direction although the
CAM models are much more bullish on fog especially over the
eastern counties. Given that fog and lower stratus has really been
overdone by the high resolution models lately will hold off on
including any fog in the grids for now and will keep things quiet
with temps falling into the upper 20s to 30s.

Tomorrow, the upper ridge axis starts to move east with the
surface trough developing in the lee of the Rockies and south to
southeast winds picking up. Some of the models bring some spotty
QPF into our western and northern counties tomorrow, which isn`t
out of the question with a weak vort moving through. However, much
to today`s radar activity is not reaching the ground and not too
much will be going on tomorrow either. Kept some low POPs in the
north going but think that QPF will be minimal. After a cloudy
morning think at least the southern counties will see sunshine
tomorrow and with 925mb temps around 12 C. Temps should get well
into the 50s in the south and trees in the east with 40s further
north.

.LONG TERM...(Sunday night through Saturday)
Issued at 303 PM CST Sat Feb 18 2017

The recent quiet stretch of weather will come to an end as a more
active period ramps up for the new week.

Beginning Sunday night, a surface low centered across eastern
Wyoming/western South Dakota is progged to swing northeast through
the forecast area. Even warmer and more moist air will advect into
the region ahead of this system with dew points possibly pushing
into the 50s in the far south. As the low moves through,
precipitation will spread from southwest to northeast across the
forecast area. Deterministic models continue to paint a broad area
of a quarter of an inch or so of (liquid) QPF while the GEFS
ensemble still depicts a wide range of amounts up to a half inch or
more (mainly east). Rainfall amounts will certainly need to be
watched as the snowpack continues to decrease and saturated soils
begin to thaw out. Additionally, a rumble of thunder or two isn`t
out of the question, especially across the south, with 100-200 J/kg
of MUCAPE and slightly negative Showalter values (also depicted by
SPC`s Day 3 Outlook).

As the low moves off to the northeast, precipitation chances will
come to an end but decent warm advection will continue with
westerly/southwesterly winds. A cooler push of air accompanied by a
fairly weak upper wave Tuesday night and Wednesday will allow
rain/snow chances to return, mainly across the north where
temperatures could cool enough for a few tenths of snow accumulation.

The second half of the week will bring a reminder that it`s not
quite spring yet as 850 mb temperatures plunge well below zero with
surface temperatures returning to more seasonal values. Models
continue to depict a strong storm system pulling out of the Rockies,
but as of now, the biggest impacts look to remain just south of the
area, more across eastern South Dakota and southern Minnesota. Will
continue to monitor for any northward shifts in the track of this
system.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1229 PM CST Sat Feb 18 2017

All sites are VFR with only some high clouds moving into the area.
More mid level and high cloud will move in later tonight, which
should help keep much fog from forming even as winds go light and
variable for a time this evening. Some MVFR ceilings will be
possible in the northern forecast area later in the period,
although quite a bit of model guidance has been too low with
ceilings lately. Will include some MVFR and later IFR ceilings at
KDVL and KBJI, keeping KGFK and KTVF on the lower end of VFR for
now. Winds will pick up from the east to southeast at around 10
kts by tomorrow morning.


&&

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

$$

SHORT TERM...JR
LONG TERM...Lee
AVIATION...JR



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