Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pendleton or
1032 PM PDT Tuesday Oct 21 2014
Updated aviation discussion
Short term...tonight and Wednesday...a large area of low pressure
will be stationed over the eastern Pacific with a cold front coming
onto the coast tonight. This front will be very slow to move
eastward but will begin to produce precipitation along the Cascades
and east slopes late tonight and early Wednesday then reaching the
eastern zones late Wednesday afternoon and evening. This front is
supported by a fetch of moisture coming across the Pacific Ocean.
The slow moving nature of the front will allow for some hefty
precipitation totals to occur over the next 24 to 48 hours
especially near the Cascade mountains. Will see an increase in
southerly winds ahead of the front but not expecting any need for
advisories. The southern portion of the Grande Ronde Valley will see
some of the strongest winds of around 30 miles per hour and gusts around 40
miles per hour.
Aviation...06z tafs...VFR conditions should prevail next 24
hours...but expect clouds to be lowering and rain increasing which
could result in some MVFR conditions at krdm...kbdn...kdls and kykm
by Wednesday afternoon. Rain may not reach kpsc...kalw and kpdt
until late Wednesday afternoon or evening. Winds will generally
remain below 15 kts...except they will be occasionally gusty to
25-30 kts out of the south.
Previous disc... /issued 400 PM PDT Tuesday Oct 21 2014/
Short term...tonight through Friday. Weak low level instability
over the area this afternoon with scattered cumulus. This should
diminish by sunset. A large upper level low and strong jet will
impact the Pacific northwest for the next few days. Water vapor
satellite showing moisture plume enhancing offshore. This will
spread clouds across the region tonight with rain into the
Washington Cascades. For Wednesday the strong southwest flow
combined with deep moisture will bring heavy rain to the Cascades.
Lighter rain expected further east from the Cascades. The frontal
boundary and steady rain will move southeast across the forecast
area Wednesday night. The precipitation will decrease Thursday with
skies remaining cloudy. A strong low pressure system will then move
northward along the coast Friday pushing the boundary back across
the area as a warm front. This will bring another period of rain.
High temperatures over the next several days will remain in the 50s and
60s. With the active weather pattern winds will become breezy at
times with Wednesday and Wednesday night having the strongest winds.
Long term...Friday night through Tuesday...a warm front will push
through the area Friday night with a swath of rain that will move up
from the south...clearing northeast Oregon by Saturday morning.
Southerly winds will also increase during this time across central
and northeast Oregon. Breezy to windy conditions will persist
through Saturday as the cold front moves in from the West. Mountain
showers will then linger through Sunday with the upper level trough
moving over the region. There will be a break in activity Sunday
night...but another weather system will begin impacting the area
Monday afternoon. This disturbance will bring more rain as well as
breezy winds going into Tuesday. Temperatures will remain mild for
this time of year with snow levels generally above 5000 feet. Cobb
Preliminary point temps/pops...
PDT 45 69 50 62 / 10 10 80 50
alw 49 68 50 62 / 10 10 80 60
psc 48 67 51 64 / 10 30 80 30
ykm 46 58 43 59 / 30 80 100 30
hri 45 68 48 64 / 10 20 80 30
eln 46 57 43 59 / 50 90 100 30
rdm 41 63 45 58 / 10 40 90 40
lgd 41 64 48 58 / 10 10 70 50
gcd 42 64 45 59 / 10 10 70 50
dls 49 61 48 61 / 30 70 100 50
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