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Area forecast discussion...updated 
National Weather Service Pendleton or
418 am PDT Monday may 4 2015

Updated for aviation discussion

Short through Wednesday...models are in good agreement
in the short term in bringing an upper trough into the Pacific
northwest for the next couple of days. The flow aloft will switch to
be from the southwest today which will begin transport of increasing
instability and moisture into the County Warning Area. This will result in afternoon
thunderstorms...especially over the mountains. This does not look
like a huge thunderstorm outbreak and most storms will be weak to
moderate and at this time not expecting any severe storms.
Thunderstorms will be possible Tuesday and Wednesday as
well...especially over the mountains. Temperatures today will be the
warmest of the next few days with maximum readings in the middle 70s to
around 80...with mostly 60s to lower 70s in the mountains.
Temperatures will cool down about 10 degrees on Tuesday from today
due to more cloud cover the chance for showers besides cooler air
aloft moving in with the upper trough. Wednesday will have even
cooler temperatures. Winds will be mostly light but there could be
locally breezy conditions in the afternoons and evenings in the
Kittitas Valley and the eastern Columbia River gorge and possibly
the basin and Blue Mountain foothills.

Long term...Wednesday night through Sunday...probability of precipitation for the extended
have been significantly modified for the track of the low pressure
system. The low will continue to push south of the area Wednesday
evening. Have kept a slight chance of thunder over the east slopes
of the Cascades...central Oregon...and northeast mountains for the
evening. By Thursday evening the low will be centered over the
California/Nevada boarder west of Reno...leaving a deformation zone over
portions of central and northeast Oregon. Probability of precipitation north of this area
have been cut back to less than 15 percent...therefore no mention of
showers will be north of central Oregon or west of the Blue
Mountains on Friday. Northwest flow Friday evening as a weak ridge
attempts to rebuild...will keep most areas dry...will allow for some
probability of precipitation along the east slopes of the Cascades...and northeast
mountains...due to the uncertainty and potential spill over from
west side upslope showers. GFS hints at another disturbance to move
over the area Saturday night into Sunday. By Sunday evening the
model hints that the weak disturbance will close off as a low
centered over the or/California boarder off the coast. That could present a
decent thunderstorm scenario for central and possibly parts of
northeast Oregon...but will hold off on mention of thunder for European model (ecmwf) has a different solution. Weber


Aviation...12z VFR conditions will persist for the next 24 hours
across all taf sites. Few-scattered clouds around 25kft with few clouds
at 8kft this afternoon. Winds will pick up after 18z and be mainly
out of the west-northwest. Expect winds to be 10-15 kts...gusting as high as
25 kts. Weber


Preliminary point temps/pops...
PDT 77 43 65 39 / 0 0 10 20
alw 80 45 67 42 / 0 10 10 20
psc 82 45 70 41 / 0 0 10 20
ykm 79 41 66 38 / 0 0 20 30
hri 80 45 69 41 / 0 0 10 20
eln 76 42 63 37 / 0 0 20 30
rdm 75 34 61 32 / 0 0 10 10
lgd 76 38 62 37 / 20 20 10 10
gcd 82 38 64 35 / 20 10 10 10
dls 79 44 66 41 / 0 10 20 30


PDT watches/warnings/advisories...

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