Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus66 kpdt 230927 

Area forecast discussion
National Weather Service Pendleton or
227 am PDT Sat Jun 23 2018

Short through Monday...a northwest flow aloft today
will keep cooler and dry conditions over the forecast area through
tonight. There may be a few light rain showers along the central
Washington Cascade east slopes this morning due to an upslope flow
into the Cascades with some spill over. But it will be dry over the
rest of the County Warning Area. A building and amplifying upper ridge will move
into the Pacific northwest on Sunday with the ridge axis reaching
the Cascade Range by 12z (5 am pdt) Sunday morning. This ridge will
bring a sharp warming trend on Sunday from temperatures today. Highs
on Sunday in the lower elevations will be into the lower 90s with a
few locations possibly reaching the mid 90s. In the mountains
temperatures will be mostly in the 70s to lower 80s. The next
weather system and its upper trough will begin to move into the
region Sunday night into Monday. This will bring cooler temperatures
with a marine push and increasing winds...especially along the
Cascade east slopes, the eastern Columbia River gorge, the lower
Columbia Basin, the Blue Mountain foothills and the Kittitas Valley.
However, the winds will not be as strong as they were on Friday.
This system will have very limited moisture and can expect only some
light rain showers over the Washington Cascade east slopes on
Monday. Temperatures on Monday will cool back down to the lower to
mid 80s in the lower elevations with 60s to mid 70s mountains. 88

Long term...Monday night through Saturday...winds will taper off
Monday evening as pressure gradients equalize across the Cascades
behind a departing cold front. High zonal flow becomes established
behind the departing system Tuesday through Thursday morning with
dry westerly flow and near zero precipitation chances. Weak onshore
flow will keep westerly afternoon winds in the 10-15 mph range
during this period which may aggravate any continuing wildfire
suppression efforts. Models have come into a little better agreement
with deepening longwave trough Thursday into the weekend. Main
impacts from this system will be breezy winds during the day
Thursday with strengthening onshore flow and a slight chance of
showers into Friday and Saturday as an upper level low becomes
established over the forecast area. Given rather meager mid-level
lapses even with upper low overhead have kept any mention of
thunderstorms out of the forecast for now. Peck


Aviation...12z tafs...the pressure gradient across the Cascades
will continue to relax through this afternoon as upper level ridging
builds into the region with winds trending down for rdm/bdn/dls/PDT
through late this afternoon. Scattered-broken mid-level cigs in the vicinity
of PDT/alw this morning associated with marine influenced air
ridging up into The Blues will dissipate through the afternoon as
mixing increases. North-northwest transport winds should keep most
smoke from central Oregon fires away from the taf sites this
morning. Peck


Preliminary point temps/pops...
PDT 80 55 90 59 / 0 0 0 0
alw 81 58 91 62 / 0 0 0 0
psc 85 57 92 63 / 0 0 0 10
ykm 82 54 89 58 / 0 0 0 10
hri 84 57 93 62 / 0 0 0 0
eln 77 54 88 56 / 0 0 0 10
rdm 78 46 92 51 / 0 0 0 0
lgd 73 49 85 54 / 10 10 0 0
gcd 73 49 85 54 / 10 0 0 0
dls 80 57 92 60 / 0 0 0 0


PDT watches/warnings/advisories...

National Weather Service Glossary of Abbreviations