253
FXUS66 KPDT 271145
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
445 AM PDT Wed May 27 2026

.KEY MESSAGES...

- Chances of thunderstorms for Central Oregon Wednesday with
  more widespread coverage on Thursday. Hail and gusty winds are
  possible embedded in these storms.

- Minor heat risk for today and Thursday, with greater risk on
  Thursday before thunderstorm development.

- Breezy to windy conditions develop on Friday.

&&

.DISCUSSION...
Overhead ridging will bring dry conditions in the short term,
with the cut-off low pressure system situated over Nevada and
California bringing enough lift to initiate isolated
thunderstorms in Central Oregon through Wednesday. Sufficient
daytime heating through Thursday will build minor heat risk
across the region with values of "1" on Wednesday, with more
widespread pockets of "2" on Thursday (70-90% chance). High
temperatures will climb into the high 80s to low 90s by
Thursday. Consequently, this will enable thunderstorm
development with abundant atmospheric energy in the later
afternoon hours Thursday, increasing our chances of
thunderstorms across the region to 30-40%.

GFS deterministic advertises high CAPE values of up to 1200
J/kg and dew point values in the mid to high 50s, with the
highest values situated across the Foothills of the Blues and
going up into the Northern Blue Mountains. ECMWF backs up higher
than usual CAPE values Thursdays with relative forecasts of 0.7
to 0.91 and a shift of tails of 0 to 1. Widespread low-level
lapse rates of 8.8 to 9.2 degrees is present with mid-level
rates between 8.2 to 8.7 degrees. Looking at soundings, there`s
an apparent cap at around 800 mb that is preventing the storms
from tapping into the full available energy. Depending on
whether storms can overcome the cap will determine if storms
will be stronger than anticipated. Per SPC, the entire CWA is
fully in a marginal risk Thursday with 5% chances of severe wind
and/or hail embedded with these storms. Regardless, gusty
outflows is likely from any strong developing storms, bringing
erratic 40-60 mph gusts.

For Friday, a cold front passes through the region that will
develop tight pressure gradients and bring along breezy to
gusty winds across the region. Thunderstorm formation will be
limited to the eastern part of the CWA near the Wallowas and
parts of the Foothills of the WA Blues (15 to 25% chance) as the
low moves off to the east. Conditions quickly become more dry
over the weekend as the pattern becomes more zonal/slightly
ridged over the PacNW and a warming trend continues.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
VFR conditions persist through the TAF period. Dry conditions
persist with the exception of BDN and RDM that have a PROB30
chance of some isolated thunderstorm development from 04Z to
07Z. Heavier showers and storms will produce temporary sub-VFR
conditions with low visibility and cloud decks.

&&

.Preliminary Point Temps/PoPs...
PDT  79  51  86  52 /   0  10  20  50
ALW  81  57  87  58 /   0  10  20  50
PSC  85  55  93  55 /   0   0  10  50
YKM  87  57  93  56 /   0   0  10  70
HRI  82  54  89  54 /   0   0  10  60
ELN  82  55  89  53 /   0   0  10  60
RDM  78  45  79  43 /   0  50  90  90
LGD  79  49  86  50 /  20  20  40  50
GCD  79  45  81  45 /  20  50  80  50
DLS  86  59  90  56 /   0   0  20  70

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...None.
OR...None.

&&

$$

DISCUSSION...95
AVIATION...95