051
FXUS66 KPDT 091722
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1022 AM PDT Wed Jul 9 2025

Updated Aviation Discussion

.AVIATION...18Z TAFs...VFR conditions to prevail through the
period. A cold front passing through the area will bring some
occasional few-bkn cloud decks above 10kft AGL through this
evening. Winds will increase to 12-20kts with gusts to around
25kts at sites RDM/BDN/YKM/ALW/PSC this afternoon, becoming 12kts
or less after 4Z-5Z. At sites DLS/PDT, winds will be increasing
to 17-25kts with gusts up to 35kts this afternoon, with winds
decreasing to around 12kts at site PDT by 8Z, and winds 12-20kts
with gusts to around 30kts at site DLS after 4Z. Lawhorn/82

PREV DISCUSSION... /issued 141 PM PDT Tue Jul 8 2025/

.SHORT TERM...Tonight through Thursday...Satellite imagery this
afternoon shows mostly clear conditions across the region, though
cumulus fields are beginning to develop along the higher terrain
of central and eastern OR.

Upper level ridging over the PacNW will begin to break down later
this evening as a developing trough offshore begins to move
inland. However, the influence of the upper ridge will continue to
be felt across the region today, as high temperatures across the
Columbia Basin increase into the lower 100s, with widespread mid
to upper 90s elsewhere. Ahead of the trough, southwest flow has
developed across the PacNW, leading to increasing instability
across central and eastern OR this afternoon. Isolated to widely
scattered thunderstorms (15-20% chance) developing in these areas
throughout the afternoon and evening will be able to tap into that
instability, but also tap into the strong low to mid level lapse
rates. All that said, shear aloft doesn`t look to favor
maintaining storms, so gusty outflow winds from a collapsing
updraft are expected. Thunderstorm activity is expected to wane
tonight, however, an HREF member or two do depict a few storms
developing and moving along the Blue Mountain foothills tonight,
but confidence is very low (10%) in these storms developing.
Otherwise, breezy winds will begin to develop through the Cascade
Gaps as the cross Cascade pressure gradient tightens.

Wednesday, the upper trough and a dry cold front will move across
the PacNW bringing two fire weather concerns: strong winds and
another round of isolated thunderstorms. Persistent instability
across eastern OR in tandem with some divergence aloft will allow
for isolated thunderstorms (~15% chance) to develop across
southern and eastern portions of Grant county into southern Union
and Wallowa counties tomorrow afternoon and evening. As for winds,
the cold front passage tomorrow afternoon will result in
sustained winds of 25-35 mph with gusts up to 45 mph developing
through the eastern Gorge and Kittitas valley, with sustained
winds 20-30 mph and gusts up to 40 mph across the Columbia Basin
and portions of north central OR. Winds will generally be 15-25
mph with gusts 25-35 mph elsewhere in the lower elevations. The
cold front boundary will also produce cooler temperatures tomorrow
into Thursday, which will help increase afternoon RHs above
critical thresholds tomorrow. That said, the strength of the winds
tomorrow will overcome the impacts from higher RHs, necessitating
the need of a Red Flag Warning for the Columbia Basin tomorrow
afternoon and evening.

By Thursday afternoon the upper trough will have moved east of the
region, leaving behind a cooler airmass with locally breezy
conditions through the Cascade Gaps. By the evening hours, a
transient upper level ridge will slide across the PacNW, with a
more broad upper ridge beginning to develop in the northeast
Pacific. Lawhorn/82

.LONG TERM...Friday through Tuesday...Ensemble cluster guidance
in great agreement through the extended forecast that upper level
riding will build over the northeast Pacific, with the PacNW
coming under the influence of the upper ridge (confidence 60-70%).
Flow aloft will waver from a weak zonal flow into northwest flow
aloft early next week. Temperatures will be increasing Friday into
the weekend, with a slight cool off into early next week with
northwest flow developing. Breezy winds will develop through the
Cascade gaps each day as well, but as flow aloft turns more
northwesterly, the Kittitas Valley and gaps through the WA
Cascades will see breezy to locally gusty conditions (50-70%).
Otherwise, mod-high confidence (60-80%) that the upper ridge will
suppress storm activity across the region through early next week.
Lawhorn/82

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  91  61  87  58 /   0   0   0   0
ALW  91  64  86  62 /   0   0   0   0
PSC  94  61  90  58 /   0  10   0   0
YKM  91  59  87  59 /   0  10   0   0
HRI  93  62  90  59 /   0   0   0   0
ELN  83  58  83  58 /  10  10   0   0
RDM  87  50  84  49 /   0   0   0   0
LGD  87  58  81  56 /  10  10   0   0
GCD  89  53  84  52 /  20  20   0   0
DLS  84  63  85  62 /   0  10   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning until 10 PM PDT this evening for ORZ691.

     Red Flag Warning from 2 PM this afternoon to 11 PM PDT this
     evening for ORZ698.

WA...Red Flag Warning until 10 PM PDT this evening for WAZ691.

&&

$$

SHORT TERM...82
LONG TERM....82
AVIATION...82