069
FXUS66 KPDT 100513
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1013 PM PDT Mon Jun 9 2025

Updated Aviation Discussion

.UPDATE...Clear skies throughout the region. Hit triple digits
across many parts of the Basin and the Kittitas Valley. Saw
Advisory criteria that would warrant additional highlights in the
southern foothills of the Blues and North-Central Oregon that will
remain in effect until 9 PM Tuesday.

.AVIATION...06Z TAFs...VFR conditions to prevail through the
period. A system clipping the region to the south will bring
increasing thunderstorm chances mainly south and east of sites
RDM/BDN tomorrow afternoon. That said, high-res short term model
guidance indicates a prob30 of an isolated thunderstorm or two
impacting the sites between 21Z-03Z. Otherwise, few-sct CIGS
AOA 15kft AGL will impact all sites tomorrow. Mostly light winds
will prevail tonight, then increase between 17Z-03Z at sites
PDT/RDM to 12-15kts with gusts to around 25kts. Site DLS will also
see winds increase to 12-20kts with gusts 20-30kts after 17Z.
Lawhorn/82


PREV DISCUSSION... /issued 143 PM PDT Mon Jun 9 2025/

.SHORT TERM...
Tonight through Wednesday night...
Strong high pressure remains over the Pacific Northwest. This high
will keep very hot temperatures and moderate to high HeatRisk
across much of the region today. The ridge will move a bit
eastward on Tuesday and gradually break down and we will be in a
more southwesterly flow by late afternoon early evening. Still, it
is expected to be another hot day, just not as hot as today.

Southwesterly flow will continue into Wednesday.

As the ridge moves eastward on Tuesday into Wednesday, there will
be a slight (15-20%) chance of showers and thunderstorms across
central Oregon and the Ochoco-John day Highlands Tuesday and then
more across Eastern Oregon on Wednesday. Some of these
thunderstorms will be dry, though there could be some that put
down some light (a few hundredths) amounts of rain.

There are 500 to 1000J/kg of CAPE in spots both Tuesday afternoon
and Wednesday afternoon but also some decent CIN.

Winds will increase both this afternoon and Tuesday afternoon,
with Tuesday having the stronger winds. The combination of the
strong winds and low relative humidities will yield critical fire
weather conditions and a Red Flag Warning remains in effect.
through Tuesday.

High temperature will remain above normal through the period
though they will slowly decrease. Highs on Tuesday will be in the
90s to around 100 degrees in the Columbia Basin. These
temperatures are about 20 degrees above normal. Highs on Wednesday
will be about 7 to 10 degrees cooler than Tuesday, and range
mainly in the 80s to lower 90s. These highs are still about 10
degrees above normal. HeatRisk will remain moderate across the
Columbia Basin, Yakima Valley and Blue Mountain Foothills.

The ECMWF EFI has anomalies of 0.9 to 0.95 for high temperatures
across the Columbia and Foothills of the Blue Mountains on
Tuesday and 0.8 to 0.9 for lows. EFI also has 0.7 to 0.8 for highs
on Wednesday.

.LONG TERM...
Thursday through Monday...Dry southwesterly flow will continue
through the midweek into the weekend. A weak trough may bring some
showers by Monday, but that is still a week away and is likely the
next chance of any precipitation after the isolated thunderstorms
tomorrow and Wednesday. The cooler temperatures will bring at
least some increase in RH and help alleviate fire weather
concerns. High temperatures will be close to normal Friday through
the weekend, and there will be diurnal breezes each day.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  64  97  62  91 /   0   0  10  10
ALW  69  96  66  89 /   0   0   0  10
PSC  64  99  61  94 /   0   0   0   0
YKM  64  99  62  94 /   0   0   0   0
HRI  64 100  62  93 /   0   0   0   0
ELN  64  95  61  89 /   0   0   0   0
RDM  56  94  50  86 /   0  10  10   0
LGD  61  92  60  85 /   0   0  10  20
GCD  59  93  58  87 /   0  20  40  30
DLS  64  94  62  85 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory until 9 PM PDT Tuesday for ORZ041-044-507-508-510.

WA...Heat Advisory until 9 PM PDT Tuesday for WAZ024-026>029.

     Red Flag Warning until 8 PM PDT Tuesday for WAZ690-691.

&&

$$

UPDATE...95
SHORT TERM...77
LONG TERM....77
AVIATION...82