Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus66 kpdt 221001 cca 

Area forecast discussion...corrected
National Weather Service Pendleton or
252 am PDT Sat Jul 22 2017

Short through Monday night. Dry westerly flow aloft
today with sunny skies. A front moving into southern British Columbia will
continue to bring scattered clouds to the Washington Cascades this
morning. 850mb temperatures increase today with building upper
level ridge and high temperatures will be 3-7 degrees warmer than
yesterday. An upper level low will be approaching the northern
California coast Sunday. Instability will be increasing over
central Oregon and expect cumulus development in the afternoon.
Could have isolated thunderstorms over the southern Cascades
late. Remainder of the forecast area will have another sunny day
with highs in the 90s to near 100. Warmest temps will be in the
Columbia Basin. Surface gradients indicate a little more wind
Sunday especially Kittitas Valley and gorge. The upper low will
slowly move into northern California and southern Oregon Sunday
night and Monday. This will increase the coverage of showers and
thunderstorms. Mainly impacting central and northeast Oregon. To
the north of this area it will be partly cloudy and continued
warm. 94

Long term...Tuesday through Friday...mid/upper low along northern
California coast continues to spread mid level moisture and
associated elevated instabiity into central and NE Oregon. This sets
the stage for a good chance of thunderstorms Tuesday and Wednesday
in The Highlands/mountains of central Oregon and the Blue Mountains.
As the low enters the forecast area it opens up to a negatively
tilted trough with its amplitude dampening as the trough moves NE
through the forecast area. Wednesday night the upper trough swings
through far NE Oregon and exits the region by daybreak Thursday
followed by a drier SW flow aloft. The dry SW flow aloft will
persist on Thursday through Friday, which results in dry conditions
through the remainder of the long term. Tuesday looks to be the
warmest day with high temperatures in the mid to upper 90s.
Wednesday Onward will be slightly cooler with highs in the mid 80s
to lower 90s through Friday. Polan

Fire weather...low amplitude ridging will result in dry
conditions and a warming trend through the weekend. The next
significant fire weather concern will be thunderstorms for the
first half of next week. Models are coming into a little better
agreement with mid/upper level low pressure digging along the
northern California coast Sunday into Monday, then opening into a trough
and moving east/northeast Tuesday and Wednesday. With the flow
becoming more toward the southwest, sufficient moisture and
instability will work into the region for some thunderstorm
development. Initial storms would likely develop across central or
Sunday evening, pushing east to the southern blues Monday, then
into northeast or Tuesday/Wednesday. With limited deep layer
moisture initially, will keep thunderstorm wording at slight
chance through Monday. Looks like the greatest risk will be on
Tuesday, and will use chance wording for thunderstorms. Given
significant uncertainty remaining will not issue any watches.


Aviation...VFR conditions will continue for the next 24 hours
across all taf sites. Polan


Preliminary point temps/pops...
PDT 92 64 98 63 / 0 0 0 0
alw 94 68 99 66 / 0 0 0 0
psc 96 66 101 64 / 0 0 0 0
ykm 94 65 99 62 / 0 0 0 0
hri 95 66 100 64 / 0 0 0 0
eln 91 63 92 58 / 0 0 0 0
rdm 91 56 97 57 / 0 0 0 20
lgd 89 57 95 57 / 0 0 0 10
gcd 92 58 97 60 / 0 0 0 20
dls 95 67 97 65 / 0 0 0 0


PDT watches/warnings/advisories...

National Weather Service Glossary of Abbreviations