650
FXUS66 KPDT 282334
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
434 PM PDT Thu May 28 2026

.KEY MESSAGES...
- Scattered thunderstorms capable of strong/damaging gusts and
  isolated large hail will impact the forecast area this
  afternoon and evening

- Heavy downpours embedded within thunderstorms will bring an
  excessive rainfall threat to the Cascade east slopes today

- Breezy to locally gusty winds through the Cascade gaps and
  Lower Columbia Basin Friday

&&

.DISCUSSION...
Severe convection an brief heavy rains are going to be the
primary weather hazards today following afternoon low end heat
risk (category 2) over the Washington Columbia Basin and Yakima
Valley and Eastern Columbia River Gorge. Highs This Afternoon
will peak in the low 90s in the and Lower Columbia Basin, and
into the mid 80s across central Oregon and the Blue Mt
Foothills. The category 2 heat risk (moderate) affects those who
are sensitive to heat especially those without cooling/hydration
and some health systems and industries.

Shallow convection has already developed across the northern
periphery of the upper low, namely across Crooks into southern
Deschutes counties with occasional dry lightning noted on ETLN 5
and 1 minute. Interestingly HRRR modeled updraft helicities are
not very robust as the modeled convective elements move into
the PDT CWA after mid afternoon which could limit the frequency
of severe events (hail/damaging wind reports).

The general trend is for the southwest to northeast broken
linear convection to spread into southern Oregon and the Blue
Mountains from mid afternoon though about early evening before
continuing north into a lower CAPE environment across the
Washington Valleys and Upper Columbia Basin late this evening.
The HREF Cams solutions with the most scenarios of longer lived
and stronger rotating storms favors the Ochoco  John Day
Highlands and Deschutes County and the Oregon counties in
general. Precipitation potential from the NBM mean ranges for up
to one tenth of an inch over the Lower Columbia basin and
expansion to one quarter inch across the rest of the forecast
areas, with the exception of much higher rainfall amounts in
three quarter of an inch to one inch range over central Oregon
and the Oregon Eastern Slopes. Local flash flooding is possible
in these areas especially over any preexisting burn scars over
the last could of years with these rains upwards of an inch
overnight.

Beyond the convective setup for look for stronger wind speeds
and gusts especially though the Kittitas valley On Friday based
on gap winds/gradient forgings.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
VFR conditions will primarily be dominant, with the exception
of brief PROB30 heavy thunderstorms impacting TAF sites through
06Z. More moderate showers to heavy thunderstorms will reduce
visibilities with low cloud decks temporarily. As soon as storms
pass, there`s a high likely hood that conditions remain VFR.
Other hazards associated with thunderstorms will be small hail
and brief erratic 40-60 mph gusts. Dry conditions persist after
storms pass this evening with breezy conditions of 20-30 knot
gusts developing.

&&

.Preliminary Point Temps/PoPs...
PDT  51  69  42  67 /  60  10  10   0
ALW  57  72  47  68 /  50  10  10   0
PSC  54  75  45  73 /  70  20  10   0
YKM  57  73  43  72 /  90  40  10   0
HRI  54  70  44  70 /  60  20  10   0
ELN  54  66  40  64 /  80  40   0   0
RDM  42  59  32  62 /  90  60  10   0
LGD  48  72  42  64 /  60  50  10   0
GCD  42  69  37  65 /  60  60  20   0
DLS  55  67  45  69 /  90  40   0   0

&&

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

&&

$$

DISCUSSION...71
AVIATION...95