Sunnyside, Washington Weather Forecast Discussion

578
FXUS66 KPDT 210546
AFDPDT
Area Forecast Discussion
National Weather Service Pendleton OR
1046 PM PDT Sat Sep 20 2025
Updated Aviation Discussion
.AVIATION...06Z TAFs...VFR conditions forecasted to prevail
through the period. A cold front passage tonight through tomorrow
will bring rain impacts to sites DLS/YKM/PSC/PDT/ALW. Showers with
the cold front will be capable of producing MVFR or lower
CIGS/vsby, however confidence was too low (15-30%) to include in
the forecast. CIGs will increase ahead of the cold front tonight,
but are expected to become clear or few decks behind the frontal
passage. Winds will increase to 12-20kts with gusts 20-30kts at
all sites with the initial approach and passage of the cold front
boundary. Otherwise, winds will be mostly 12kts or less, except
at site DLS where 12-15kt sustained winds and gusts to around
21kts will continue through 10Z. Lawhorn/82
PREV DISCUSSION... /issued 156 PM PDT Sat Sep 20 2025/
.DISCUSSION...Satellite imagery reveals multiple features of
interest in the Pacific. A closed low centered off the coast of
central California is advecting remnants of tropical moisture
northward into the Blue Mountains region, leading to PWATs of
150-200% of normal. To the northwest, a closed low is churning in
the Gulf of Alaska, and water vapor imagery shows a shortwave
diving southeast towards the Pacific Northwest. Ahead of the
shortwave, a frontal boundary is draped from Vancouver Island
southwest into the Pacific.
Today, there is a slight chance (10-15%) of isolated showers and
thunderstorms across the Blue Mountains, roughly from the Bend
metro area eastward. Cross-Cascade pressure gradients will drive
breezy winds through the Cascade gaps into wind-prone areas of the
Columbia Basin today. While some areas will approach Red Flag
thresholds for wind and low relative humidity, confidence was too
low (

NWS PDT Office Area Forecast Discussion