textproduct: Pendleton

KEY MESSAGES

- Above normal temperatures again today.

- Low pressure approaching the coast will breezy conditions today and Thursday, increased fire weather concerns, followed by cooler more seasonal temperatures.

DISCUSSION

The Pacific Northwest will remain under southwest flow aloft, which will strengthen today, as the area is between strong high pressure near the four corners and approaching low pressure from the Pacific Ocean.

As a result, today looks to be one last day of above normal temperatures with highs in the low to mid (and possibly upper) 90s across much of the area. Additionally, expect winds to increase, especially during the afternoon hours across the Kittitas Valley, Simcoe Highlands, Columbia Basin and Gorge. Wind gusts in these areas should reach 25 to 35 mph. NBM probabilities of wind gusts >=25 mph are all well over 80 percent, while wind gusts >= 39 mph are fairly low (<20 percent) except for some local areas >40 percent.

The low off the coast will move inland in British Columbia on Thursday. The associated trough will generally stay to the north but a front will come through, and a second, stronger trough will move through on Friday. Behind this second trough, a more westerly zonal flow will develop through the weekend, before southwesterly flow develops ahead of another upper low early next week. With the low early next week, there could be some mountain showers. Could the weather pattern be shifting to fall?

Winds on Thursday look to be very similar to Wednesday, but a bit more widespread. However, with temperatures 5 to 10 degrees cooler on Thursday, With the cooler temperatures RH values will be anywhere from 1 to 2 to 7 to 10 percentage points higher. This will help with fire weather concerns on Thursday. Winds will remain breezy on Friday, in the 10 to 20 mph range.

Winds will increase again in the 20 to 30 mph range, possibly as high as 35 mph as the next trough moves through. NBM probabilities of wind gusts >=25 mph are greater than 80 percent in the normally breezy locations, but NBM probabilities of wind gusts >= 39 mph are generally less than 40 percent.

Wind gusts could increase again early next week with the next system.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Mostly VFR conditions to prevail through the period. Sites RDM/BDN/ALW will see a 20-40% chance of smoke impacts overnight, especially when winds weaken in the overnight period. Winds will increase to 12-20kts with gusts 20-30kts at most sites this afternoon, which will become 12kts or less overnight. Sites ALW/PSC are expected to remain around 12kts or less through the period. Lawhorn/82

FIRE WEATHER

Winds will increase across the region today, but especially over the Columbia basin and Gorge. THese winds coupled with very warm temperatures and low RH values will create localized critical fire weather concerns. On THursday, winds will be similar to today, but temperatures will be 5 to 10 degrees cooler than today, which will allow for a rise in RH. Therefore, while fire weather conditions will be elevated there should be a decrease from today.

Preliminary Point Temps/PoPs

PDT 92 56 83 47 / 0 0 0 0 ALW 94 63 85 54 / 0 0 0 0 PSC 96 63 88 52 / 0 0 0 0 YKM 95 61 87 55 / 0 0 0 0 HRI 94 63 86 54 / 0 0 0 0 ELN 91 55 78 49 / 0 0 0 0 RDM 91 50 84 42 / 0 0 0 0 LGD 97 56 89 48 / 10 0 0 0 GCD 96 56 91 52 / 0 0 0 0 DLS 89 63 81 57 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Air Quality Alert until noon PDT today for WAZ026-028>030-522- 523. OR...Air Quality Alert until noon PDT today for ORZ044-502-503-507.