textproduct: Pendleton

KEY MESSAGES

- Quiet, dry weather with diurnal winds/breezes through this week.

- Elevated fire weather conditions/concerns continue with breezy winds and low RH persisting.

- Air Qualities Advisories/Alerts persist through Monday.

DISCUSSION

A mean upper trough was in place with a center of low pressure at 500 mb off the nrn BC coast. Southwest flow aloft across the Pacific and Interior NW Today is resulting in a surface ridge of high pressure across the coastal Oregon areas and across the Columbia Basin of WA/OR. This will largely result in light to slightly breezy winds over the next couple of days with terrain driven winds overnight as boundary layer mixing ceases. On Monday most of of the middle range models (EC/HI-Res ARW, GFS NAM), are showing a stronger compact vorticity core move into the base of the upper trough and that should promote a frontal passage for the region Monday night and Tuesday, which will have little impact on temperatures but keep weather temps steady though mid week. It may uptick the moisture profiles Tuesday before a drying out (lower dew points) begins Wednesday, allowing temperatures to begin to rise each afternoon back through the low to mid 90s, peaking on Friday. Models are leaning toward a frontal passage after Friday that would leave more windy conditions across the greater area with increased risk for fire weather impact levels based on low RH and winds. In the meantime, AQI remains in the 150 to 500 range across in the vicinity of the larger fires across the Blue Mountains and adjacent foothills zones, and air quality advisories remains in effect for these areas from central Oregon to the Wallowas as well as southeast Washington/Walla Walla county to the Tri Cities east of the Columbia River . The Air quality advisories are in effect though Monday afternoon and may be extended based on DEQ evaluation.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

VFR conditions currently across all sites, which will stay the course through the period. Haze/smoke from nearby wildfires will drop visibilities to 6SM at KPDT overnight through much of the day on Monday. Winds continue to subside this evening, but breezy winds of 10-20kts with gusts of 20-25kts will return for KDLS/KRDM/KBDN through the afternoon. 75

FIRE WEATHER

No red flag warnings are anticipated for this forecast/model cycle. The areas south and west of of White swan/Harrah/Toppenish could see meteorological red flag conditions briefly late this afternoon into early evening that could last as little as an hour in any locations along the fire zone 694/691 interface. For Monday relative humidity will continue to be very dry to critical across the OR/WA691 zones to the Wallowas and Grand Ronde valley eastern OR700 and the John Day basin, but lacking winds. The reverse is true over central Oregon and and northern central Oregon where breezy conditions meets a little more moisture to prevent red flag.

Preliminary Point Temps/PoPs

PDT 59 88 57 87 / 0 0 0 0 ALW 63 90 63 89 / 0 0 0 0 PSC 62 92 61 91 / 0 0 0 0 YKM 58 91 59 89 / 0 0 0 0 HRI 62 91 61 89 / 0 0 0 0 ELN 56 84 56 81 / 0 0 0 0 RDM 54 88 50 87 / 0 0 0 0 LGD 60 90 56 89 / 0 0 0 0 GCD 57 92 54 92 / 0 0 0 0 DLS 61 88 62 84 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Air Quality Alert until 11 AM PDT Monday for WAZ028>030. OR...Air Quality Alert until noon PDT Monday for ORZ049-050-502-503- 505-506-508-509-511.