740
FXUS66 KPDT 141032
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
332 AM PDT Fri Aug 14 2026

.KEY MESSAGES...

1. Isolated to scattered thunderstorms with abundant lightning and
   gusty outflow winds
                 *Red Flag Warning In Effect*

2. Sunday continued southwest flow will bring chances of
   thunderstorms and showers.

&&

.DISCUSSION...
Current nighttime satellite shows some mid level clouds lingering
over the region. Radar shows a few returns along the eastern
mountains but thunderstorms quickly teetered out earlier this
evening. Overnight temperatures will be in mostly in the 50s with
isolated areas in the Basin seeing low 60s.

Southwest flow aloft will continue over the region with a trough
just off the coast. Models show a shortwave will make its way into
the region bringing with it increased moisture form the south. this
will lead to increased chances of thunderstorms and showers. Looking
at forecasted RAP soundings, there are MUCAPE values between 250-400
J/kg, LIs of -3, lapse rates between 7.5-8 C/km and effective bulk
shear of 18 kts. This is just enough instability to allow for
isolated to scattered thunderstorms across central OR and the
eastern mountains today with 30-55% chances. Also, the flow tilts
enough to allow for moisture (PWATs 0.60-0.70 inches) to surge into
the WA Cascades and again MUCAPE values above 300-500 J/kg, LIs of -
3, lapse rates above 8-9 C/km and shear of 15 kts. That coupled with
orographic lift will lead to isolated thunderstorms along the eastern
slopes of the WA Cascades this afternoon. Even with the increased
chances of showers accompanying these storms, there is moderate
confidence (60-70%) of elevated fire weather conditions developing
due to lightning potential outside of rain cores and gusty outflow
winds. Therefore a Red Flag Warning has been issued for these areas
through & PM Friday.

Models show another shortwave is expected to move across the
southwest flow bringing in another round of thunderstorm chances
Saturday (30-50%). The flow will again allow for convection to occur
over the WA Cascades. Forecast sounding show Saturday to have values
above 250 J/kg, LIs of -1, lapse rates above 7 C/km and shear of 20
kts. While these are a bit weaker than Fridays values, we cannot
rule out an isolated storm or two across central OR, the eastern
mountains and the east slopes of the WA Cascades.

Sunday onward the models are phased slightly out of agreement with
the overall synoptic pattern of an offshore closed low and where
that low will go. However, mesoscale patterns show the area to
continue to be under southwest flow aloft. This will allow continued
moisture to be brought into the region. Chances of thunderstorms and
showers will continue with 15-20% probabilities over the eastern
mountains.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Mostly VFR conditions across all TAF sites through the morning.
Once sunrise occurs, smoke could settle out at RDM after 1100
bringing VIS to MVFR and there is a 30% chance BDN will see
MVFR conditions after 20Z. Otherwise, light surface smoke will
bring the remaining sites to sub P6SM. Winds will be light
through the period allowing the smoke to continue to settle.

&&

.FIRE WEATHER...
Increased moisture at the surface and incoming instability will
increase the chances (30-55%) of isolated to scattered
thunderstorms through the weekend. Abundant lighting is expected
over the eastern mountains and the WA Cascades. Not only will
abundant lightning be a concern, gusty outflow winds that
develop will be a concern as well.

&&

.Preliminary Point Temps/PoPs...
PDT  87  54  89  58 /   0   0  20   0
ALW  89  60  91  64 /   0   0  30  10
PSC  91  57  93  58 /   0   0  10   0
YKM  88  60  90  61 /  10  10  10   0
HRI  90  60  92  61 /   0   0  20   0
ELN  83  56  86  59 /  30  10  10  10
RDM  85  50  86  49 /  10  10  10  10
LGD  86  54  87  55 /  30  10  60  20
GCD  85  54  88  54 /  30  10  30  10
DLS  90  63  90  63 /  10  10  10   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Air Quality Alert until 3 PM PDT this afternoon for WAZ026>030-
     521>523.
     Red Flag Warning from noon today to 9 PM PDT this evening for
     WAZ695.
OR...Air Quality Alert until 3 PM PDT this afternoon for ORZ041-049-
     050-502-503-505-506-509>511.
     Red Flag Warning until 7 PM PDT this evening for ORZ694.
     Red Flag Warning until 7 PM PDT this evening for ORZ695-697-
     699.
     Red Flag Warning until 5 AM PDT early this morning for ORZ696-
     698.

&&

$$

DISCUSSION...90
AVIATION...90
FIRE WEATHER...90