textproduct: Pendleton

KEY MESSAGES

- Mostly warm, dry conditions persist through the next few days.

- Elevated fire weather conditions for wind/low RH continue.

- Small chance (0-10%) of dry thunderstorm development across the Southern Blues and Eastern Mountains Wednesday and Thursday.

DISCUSSION

Current satellite shows a few cumulus clouds across the Cascades with mostly sunny conditions across most of the region. Smoke and haze originating from wildfires in Central Oregon through parts of the Southern Blues is clearly visible streaming from the SW to NE, bringing hazy conditions across the Colombia Basin. An Air Quality Advisory initiated via the Department of Environmental Quality is in effect through much of the Colombia Basin and Blue Mountains through noon tomorrow due to ongoing smoke transport.

Synoptically, southwest flow continues and will persist through the next couple of days as a trough just offshore of British Colombia paves way through the PacNW through Friday evening. Periods of embedded shortwaves within the trough will bring very low chances of dry thunderstorm development (0 to 10 percent chance) across portions of the Southern Blues and Eastern Mountains, potentially triggering new ignitions. Deterministics Wednesday and Thursday advertise a pocket of very slight moist air with 45-65% RH in the low to mid levels passing through the Southern Blues and Eastern Mountains, along with 150-300 J/kg of MUCAPE developing during peak heating according to the REFS. Precipitable water values stay at below 1.00 inch in the development region (80-90% chance), suggesting any thunderstorm that initiate will be mostly dry in nature with little to no potential for wetting rains to occur.

As the trough approaches the area early Saturday morning to afternoon, tight pressure gradients will develop and bring gusty to locally windy conditions across the region. Areas across the Kittitas/Yakima Valley's, Columbia Basin of Oregon, and the Cascade Gap region have the greatest chance of exceeding wind advisory criteria (>45 mph gusts) Saturday. Chances of exceedance reaches 50-80% across the mentioned areas, with wind highlights possible as we get closer to the event. This will also consequently enable to the potential of elevated to critical fire weather conditions developing Saturday. Joint probabilities of 25% or less humidity AND sustained winds of 20 mph or more are advertised at 15-35% chances by 5 PM Saturday. Will monitor for the trend going through tomorrow to see if fire weather highlights are warranted.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

VFR conditions are expected through the TAF period, at all sites except ALW. At ALW MVFR conditions have moved in due to smoke from wildfires. Lower conditions from smoke can not be ruled out at other sites either. Winds will gust 20 to 25 kts at all terminals through this evening then decrease to 10 kts or less.

Preliminary Point Temps/PoPs

PDT 54 86 56 88 / 0 0 0 0 ALW 59 88 60 90 / 0 0 0 0 PSC 56 90 57 91 / 0 0 0 0 YKM 55 89 56 90 / 0 0 0 0 HRI 56 89 58 90 / 0 0 0 0 ELN 51 85 54 85 / 0 0 0 0 RDM 47 88 47 88 / 0 0 0 0 LGD 53 90 54 91 / 0 0 0 0 GCD 52 93 53 94 / 0 0 0 0 DLS 58 87 58 86 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...None. OR...Air Quality Alert until noon PDT Wednesday for ORZ041-044-049- 050-502-503-505>511.