textproduct: Pendleton

KEY MESSAGES

- Elevated to locally critical fire weather conditions will continue to persist through at least the better part of this week.

- Widespread moderate risk of heat expected to develop through the region by Thursday.

- Smoke and haze from local and regional wildland fires continue to suppress air quality levels through at least Thursday.

DISCUSSION

Satellite & other night time products continue to show widespread smoke and haze across the region from local and regional wildland fires ignited over the past few weeks. Smoke is expected to linger through at least Thursday (>90% chance) as a ridge located offshore continues to move towards the region through Thursday. This has allowed unhealthy levels of air quality to accumulate, thus local agencies from Oregon & Washington have issued Air Quality Alerts/Advisories for the entire forecast area.

With the ridge axis expected to reach over the area in the Thursday/Friday timeframe, we expect a warming trend to continue until then with the NBM advertising chances of reaching triple digits in parts of the Columbia Basin at around 30-50%. Guidance is in very good agreement with HeatRisk values reaching 'moderate' with widespread chances of 80-100%. Isolated areas of major HeatRisk is possible with 30-50% chances possible Thursday & Friday in parts of the Yakima/Kittitas region. With that being said, wildland fire smoke could inhibit the ridge bringing its full potential of heat. Areas with thicker columns of smoke may fall short several degrees than otherwise expected, possibly tapering levels below major that would've reached it otherwise. This brings issuing heat advisories at a low confidence (10-30%) due too the difficult to forecast smoke plumes in the area.

Guidance in the synoptic level through the weekend is in good agreement that the pattern will turn into a zonal/quasi-zonal flow with tighter pressure gradients, resulting in breezy to locally windy conditions developing late this week. With dry air lingering with minimum relative humidities still in the 10-18 percent range Friday and Saturday, chances of critical weather conditions developing go up with 20-30% confidence. The main factor in increased confidence will be how far and widespread the winds will be. Although local areas are expected to be critical, it's not anticipated it will be a widespread event, thus no fire weather highlights will be issued for the weekend at this time.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Widespread smoke and haze from local and regional wildland fires continue to impact all TAF sites through the next 24-hours. Smoke plumes are large enough to bring at least MVFR and IFR conditions at all sites, with persistance through the TAF period. There's a small chance (5 to 15 percent) of seeing smoke levels temporarily improving to VFR with daytime heating mixing smoke levels.

Preliminary Point Temps/PoPs

PDT 93 58 97 62 / 0 0 0 0 ALW 94 63 98 68 / 0 0 0 0 PSC 95 59 100 61 / 0 0 0 0 YKM 94 62 98 63 / 0 0 0 0 HRI 95 60 99 64 / 0 0 0 0 ELN 92 61 96 63 / 0 0 0 0 RDM 96 53 99 55 / 0 0 0 0 LGD 96 58 100 61 / 0 0 0 0 GCD 98 58 101 60 / 0 0 0 0 DLS 97 64 99 64 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Air Quality Alert until 5 AM PDT Tuesday for WAZ024-026>030- 521>523. OR...Air Quality Alert until 5 AM PDT Tuesday for ORZ041-044-049- 050-502-503-505>511.