Scientific Forecaster Discussion
fxus66 kpdt 141708 aaa
Area forecast discussion
National Weather Service Pendleton or
908 am PST Thu Nov 14 2019
Updated aviation discussion
Short term...today and tonight...widespread stratus and areas of
fog continue to blanket the low elevations over most of eastern Washington
and the northern half of eastern or. Dense fog with visibilities
less than 1/4 mile have been patchy. The dense fog advisory in
effect for the blue mtn foothills is set to expire at 10 am, and the
odds are likely this will be allowed to expire. A weak shortwave
trough over southwest or will decay as it makes its way across or,
but there will be improvement in the stratus and fog. Central or
will have the best chance of clearing, but the fog may be lifted in
other areas currently in pea soup with less fog coverage.
Temperatures have been a challenge due to the overcast stratus with
big differences in temperatures compared to those above the
inversion. Afternoon highs will be in the 40s in the lower
elevations and in the 50s for areas lucky enough to see the sun
today. The inversion is shallow and primarily above 2000 feet, but
some of the high valleys such as the grande ronde valleys are
observing fog this morning.
Only updates to the forecast have been to add drizzle for the blue
mtn foothills and the eastern portion of the lower Columbia Basin.
Aviation...18z tafs..widespread IFR ceilings/visibilities this
morning will improve to MVFR/VFR this afternoon. Conditions will
likely deteriorate somewhat overnight tonight...but probably not as
bad as early this morning since an approaching storm system will
provide some large scale lift by early Friday morning. Some light rain
will impact the western tafs after 12z. Winds will be light and
Previous discussion... /issued 343 am PST Thu Nov 14 2019/
Short term...an upper level trough and cold front will move through
the area on Friday. Most locations should receive some light rain
with the front. Highest amounts will be the Cascades and blues.
Winds at 850-700mb will increase to 25-35kt with some cold
advection. Expect this will help mix out the boundary layer and
temporarily eliminate the low clouds and fog. Upper ridge builds
back into the region Saturday with partly to mostly cloudy skies.
Fog in the Columbia Basin likely returning Sat night.
Long term...Saturday night through Wednesday. Models are in fairly
good agreement in saturday's dry respite returning to a more moist
pattern as a plume of moisture north of US settles southward. This
brings a slight increase in shower chances to mountainous areas on
Sunday with minimal impacts to basin and valley areas. On Tuesday, a
more organized system brings better and more widespread moisture to
the area as well as a colder airmass. Valley rain and mountain snow
are expected. There remains some modest differences between the
timing and organization of this system as it moves into the pac northwest.
This system is expected to usher a more seasonably cold airmass into
the region for mid next week.
Preliminary point temps/pops...
PDT 43 36 52 37 / 10 0 40 20
alw 44 37 50 39 / 10 0 50 20
psc 47 36 53 36 / 0 0 40 0
ykm 47 36 51 34 / 0 10 40 0
hri 47 37 54 37 / 10 0 30 10
eln 47 36 50 34 / 0 10 50 10
rdm 55 34 57 30 / 0 0 40 10
lgd 56 39 53 34 / 0 0 50 30
gcd 57 37 54 33 / 0 0 40 20
dls 48 39 54 39 / 0 10 50 10
or...dense fog advisory until 10 am PST this morning for orz507.
Washington...dense fog advisory until 10 am PST this morning for waz029.
Air stagnation advisory until noon PST Friday for waz027.