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fxus66 kpdt 081731 

Area forecast discussion
National Weather Service Pendleton or
931 am PST sun Dec 8 2019

Updated aviation discussion.

Update...upper trough will move south and east of the area by
this evening ending any precipitation over the eastern mountains
this afternoon. The dense fog has mostly dissipated so have
discontinued the dense fog advisory with this forecast package. A
ridge of high pressure will build over the area tonight so expect
the fog and stratus to redevelop. That will be the main forecast
concern the next couple of days. Made minor adjustments to high
temperatures and afternoon probability of precipitation for today otherwise current
forecast is on track. 78

Aviation...18z tafs...fog remains across the Columbia Basin
impacting kdls, kpdt, kalw, kpsc & kykm. Conditions will likely vary
between IFR/MVFR through 22z this afternoon before fog begins to
lift and visibility improves. Upper level ridge will keep weather
calm through the period, but fog likely will develop again overnight
across the area with IFR conditions expected everywhere except
krdm/kbdn. In areas where fog becomes dense, LIFR conditions can be
expected. Richards


Previous discussion... /issued 301 am PST sun Dec 8 2019/

Short through Tuesday upper level trough
will slowly exit the region today with showers over the eastern
mountains coming to an end this afternoon. There will be some areas
of clearing today mainly in the western portion of the forecast area
but remaining mostly cloudy in the east associated with the
aforementioned showers. There will also some persistent fog and
stratus especially along the foothills of the Blue Mountains and
eastern portion of the lower Columbia Basin today. A ridge of high
pressure will build in from the west tonight so we will see more
spread and growth of the fog and stratus as inversion strengthens
which will persist into Tuesday. Then a weak system moving through
the ridge will push a weak cold front across the forecast area late
Tuesday and Tuesday night. Precipitation amounts associated with
this system are expected to be light and do not expect any major
snow accumulations in the forecast area.

Long term...Wednesday through Sunday...models in good agreement
through the period as a very active weather pattern sets up over the
Pacific northwest. Light to moderate rain and mountain snow will
begin to fall along the Cascades late Wednesday afternoon and
spreading eastward Wednesday night. The steady precipitation will
continue through Thursday, but it should begin to decrease over the
Columbia Basin by Thursday night. A brief break is expected on
Friday with only scattered showers expected over the mountains. The
next system approaching from the south should begin to spread
another area of widespread rain and mountain snow over our southern
County Warning Area Friday night. The precipitation is expected to spread northward
Saturday. A shortwave ridge is expected to develop in the wake of
the aforementioned system on Sunday resulting in a short-lived
drying trend. Daytime highs are expected to be near to slightly
above normal through the period. Earle


Preliminary point temps/pops...
PDT 45 32 38 31 / 10 0 0 0
alw 44 34 39 32 / 10 0 0 0
psc 45 33 38 32 / 0 0 0 0
ykm 46 30 39 30 / 0 0 0 0
hri 46 32 38 31 / 0 0 0 0
eln 44 30 39 30 / 0 0 0 0
rdm 48 25 47 26 / 0 0 0 0
lgd 43 30 42 32 / 40 10 0 0
gcd 46 29 44 29 / 20 10 0 0
dls 50 35 42 35 / 0 0 0 0


PDT watches/warnings/advisories...

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