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Area forecast discussion 
National Weather Service Pendleton or
753 PM PDT Thu Oct 27 2016

Update...the cold front that brought light rain or showers to the
forecast area is slowly moving to the east and is now oriented from
the northern Blue Mountains in Washington southwest across the
Oregon Blue Mountains with light rain or showers from the Blue
Mountains eastward. This precipitation will continue to gradually
decrease through the rest of the night and will be to the east of
the County Warning Area by morning. There will be a break in the precipitation on
Friday with a low off the coast and the current front to the east of
the County Warning Area. Meanwhile the synoptic pattern will persist with an upper
high pressure ridge over the center of the County and an upper
trough off the coast with a southwest flow aloft over the County Warning Area. With
the County Warning Area being in between short wave systems a dry forecast is
expected on Friday. Then the next shortwave weather system off the
coast will move inland Friday night into Saturday bringing more rain
(and high elevation snow...with snow levels between 6000-8000 feet)
to the forecast area. There is a probability of this next system
bringing about .1 to .25 inches of additional precipitation to the
forecast area Friday night into Saturday. Snow levels will lower to
between 5000-7000 feet Saturday night into Sunday. Then another
system is expected to move across the region by Sunday afternoon
into Sunday night. Winds through this period are expected to remain
light. 88


Aviation...06z tafs...mostly VFR conditions are expected as the
current weather system moves to the east. However patchy to areas of
fog development is possible due to clearing skies with abundant low
level moisture which may cause periods of MVFR/IFR conditions at
times overnight over the lower Columbia Basin and adjacent
valleys and foothills, which will improve Friday morning as mixing
and heating takes place. Friday will become a VFR day at all taf
sites. Winds will remain light and under 10 kts through the next 24
hours. 88


Previous discussion... /issued 213 PM PDT Thu Oct 27 2016/

Short term...tonight through Sunday...the slow moving cold front
will continue to bring precipitation mainly to the eastern portion
of the forecast area through early tonight and then exit into Idaho
by early Friday. The upper level trough will remain in position off
the coast keeping US in a moist southwest flow. Conditions will
remain dry through Friday before turning wet again Saturday and
Sunday as a couple of more weather systems pass over the forecast
area. Snow levels will remain between 6000 and 8000 feet through
Saturday and then lowering to 5000 to 7000 feet Sunday.

Long term...Sunday night through Thursday...models in good
agreement in continuing the progressive weather pattern across the
Pacific northwest through the period. At this appears the
best chance of precipitation will be Sunday night as a warm front
moves through the area. By Monday afternoon...the models begin to
differ on their handling of an upper level low pressure system
approaching the West Coast. The GFS is farther south and moves it
over Southern California Monday night. The European model (ecmwf) has it farther
north and moves it over Oregon Tuesday afternoon. At this
time...will lean more towards the GFS solution which keeps a
drier...westerly flow over the area Tuesday. By Tuesday night...a
developing weak upper level ridge begins to force most of the
weather systems north of the area. Nevertheless...a chance of
precipitation will continue...albeit mostly over the
mountains...through the long term period as weak disturbances move
through the southwest flow aloft. Daytime highs will remain near
normal through the period. Earle


Preliminary point temps/pops...
PDT 41 60 42 56 / 30 0 10 50
alw 47 61 47 56 / 30 0 10 40
psc 45 59 46 55 / 10 0 10 30
ykm 39 60 43 57 / 10 0 10 40
hri 42 60 44 54 / 20 0 10 40
eln 39 57 41 54 / 10 0 10 40
rdm 33 58 37 55 / 20 0 30 50
lgd 40 58 40 57 / 50 0 10 60
gcd 41 58 43 57 / 40 10 30 60
dls 45 62 48 57 / 10 0 20 50


PDT watches/warnings/advisories...



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