textproduct: Pendleton

KEY MESSAGES

- Near-seasonal temperatures through the week.

- Transition to a convective weather pattern Today with daily shower and thunderstorm chances into next week, mainly for the mountains.

- Critical Fire weather due to lightning Risk Thursday afternoon

DISCUSSION

The region is transitioning into a convective pattern which should linger into the early weekend bringing potential each afternoon and evening of shower and thunderstorms with possible fire weather impacts due to lightning if it is abundant enough. Confidence for measurable precipitation is not high (in the 15 to 25% range) Thursday afternoon across the John Day Highlands/Basin and southern Blue Mountains however the drought with high ERCs have leaned us toward the Red Flag as NBM members area trending around 0.1 flashes /sq mile /5 mins across these zones from mid afternoon and across the overnight hours into Friday morning. HRRR smoke models show a southward push of vertically integrated smoke as showers and thunderstorms can create outflow winds across northern WA and the Upper Columbia Basin overnight and early Thursday. Temperatures continue to remain largely unchained by the pattern with upper 80s and across the Columbia Basin and cooler low 80s into the foothills and mountain zones, warming back into the 90s across the Columbia Basin by Sunday.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

VFR conditions prevail with elevated smoke over the area. Some smoke may reach surface level through the overnight hours, temporary bringing MVFR conditions to some sites (5 to 15 percent). Otherwise expecting dry conditions across the board. The main exception may be some shower/thunderstorms developing near YKM over the next several hours, but not expecting T-Storm coverage to reach that far with the main impacts near the downslope of the East Cascades. A stray shower (5 to 15 percent) may pass over YKM through 03Z, but not confident at this time to put it as a line.

FIRE WEATHER

Red Flag warnings were issued for several Oregon Fire Zones as monsoonal moisture interacts with weak upper vorticity in the mean trough from the Oregon Cascades and eastward Thursday afternoon/evening into he John Day Basin and southern Blue Mountains, even beyond midnight. The seasonal dry period with high ERCs have tipped us toward the Red Flag as NBM members are trending around 0.1 flashes /sq mile /5 mins across these zones from mid afternoon and across the overnight hours into Friday morning and any GC can create new starts. Any convection beyond Thursday will be evaluated against any wetting rain chances, which while are not high, are quite variable and at 10 to 70% on a 24 hr basis highest in the eastern Oregon zones.

Preliminary Point Temps/PoPs

PDT 52 85 54 87 / 0 0 0 0 ALW 58 87 59 88 / 0 0 0 0 PSC 57 89 58 90 / 0 0 0 0 YKM 58 88 60 88 / 20 0 10 10 HRI 55 89 57 90 / 0 0 0 0 ELN 55 83 56 83 / 40 10 20 30 RDM 44 84 48 85 / 0 0 10 10 LGD 53 86 55 86 / 0 0 30 30 GCD 52 87 54 86 / 0 0 50 40 DLS 60 91 62 91 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Air Quality Alert until 3 PM PDT Friday for WAZ026>030-521>523. OR...Air Quality Alert until 3 PM PDT Friday for ORZ041-049-050-502- 503-505-506-509>511. Red Flag Warning from 1 PM Thursday to 5 AM PDT Friday for ORZ696>699. Red Flag Warning from 1 PM to 9 PM PDT Thursday for ORZ700-705.