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Area forecast discussion 
National Weather Service Pendleton or
930 PM PDT Monday Oct 24 2016

Short term...tonight...a weakening cold front is moving through
central and north central Oregon bringing scattered showers to
central Oregon and the lower Columbia Basin of Oregon and
Washington and numerous showers to north central Oregon.
Showers will taper off and end in central and north central Oregon
by around midnight. Brief wind gusts to around 45 mph are possible
in the heavier showers ahead of the cold front until around 2-3 am.
Walla Walla Airport reported a squall of 46 mph at 907 PM. I lowered
pops in central and north central Oregon to 28-48 percent for the
remainder of this evening. Polan


Previous discussion... /issued 706 PM PDT Monday Oct 24 2016/

Short term...tonight through Thursday...overall synoptic pattern
during this time will be an upper level trough in the eastern
Pacific and an upper level ridge over the central U.S.. this will
place the Pacific northwest under a southwest flow aloft with a
series of weather systems impacting the forecast area. The first
will be occurring overnight as a weakening cold front slowly moves
eastward and exits the area by early Tuesday. The next system will
arrive as a warm front Tuesday night and Wednesday which slowly
lifts northward across the forecast area. This will be followed by
yet another weak cold front on Thursday. Tonight's precipitation
will be light and generally under a tenth of an inch. The warm front
Tuesday night and Wednesday will produce a little more precipitation
but generally over the western portion of the forecast area closer to
the Cascade mountains. Temperatures will be slightly above normal
through the short term.

The Wind Advisory for the Grande Ronde Valley has been cancelled.

Long term...Thursday night through unsettled and wet
weather pattern will continue through the long term period. Models
are in generally good agreement in having a trough centered offshore
with a series of systems moving through the area though there are
the usual timing differences. Thursday night one system will be
leaving the area with a slight chance of rain over much of the area
though the Columbia Basin and surrounding valleys will be dry. On
Friday another system will be moving in from the south with rain in
central Oregon in the morning and spreading a chance of rain across
the rest of the area in the afternoon and lasting through Friday
night. Another system arrives right on its heels on Saturday and
Saturday night with a chance of rain continuing over the area though
the Columbia Basin will have a slight chance of rain. On Sunday an
upper low will move north along the Oregon coast and then through
our area as an open wave Sunday night and Monday. This will keep a
stream of moisture over the area and there will continue to be a
chance of rain through Monday. Temperatures will be in the 50s and
lower 60s through the period. Snow levels will remain around 7500
feet before lowering to around 6500 feet on Monday so no significant
snowfall is expected. Perry

Aviation...00z tafs...broken to overcast skies at 7000-10000 feet
agl will lower to 4000-7000 feet agl this evening as a weakening
cold front moves through the area. Rain will develop at western taf
sites kbdn, krdm, kdls and kykm around 02z and continue through
around 07z. Further east, kpsc, kalw and kpdt will develop rain
around 05z and continue through 13z. After the showers end, ceilings
will clear aside from scattered high cirrus at around 20000 feet.
Southerly winds of 15 to 25 kts with gusts to 35 kts will continue
at krdm and kbdn before diminishing to below 15 kts after 03z. Winds
there will increase again tomorrow afternoon with gusts to 20 kts.
Southerly winds of 10 to 20 kts will continue at kalw and kpdt
through 04z this evening. Otherwise winds will remain below 15 kts.


Preliminary point temps/pops...
PDT 48 63 50 64 / 50 10 30 80
alw 53 64 53 65 / 60 10 20 70
psc 50 64 50 58 / 40 10 20 90
ykm 42 62 46 58 / 60 10 20 90
hri 47 64 49 60 / 40 10 30 80
eln 42 58 44 54 / 70 10 20 90
rdm 37 59 45 66 / 30 10 80 10
lgd 47 61 47 65 / 50 30 30 50
gcd 47 59 48 66 / 40 20 60 10
dls 45 64 50 60 / 70 10 70 80


PDT watches/warnings/advisories...



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