textproduct: Pendleton

KEY MESSAGES

- Diurnal breezes expected much of this week, with Tuesday and Saturday being the windiest days.

- Quiet weather for the upcoming week.

DISCUSSION

A 549 dm 500 mb low off the nrn BC coast with an attendant trough was positioned off the nrn BC coast Today. An attendant trough will swing eastward out of the NE PAC ocean into the PAC NW and Interior NW over the next 24 to 48 hours. Southwest flow aloft will overrun a high pressure at the boundary layer that will allow for some diurnally driven gap winds, especially though the Columbia River Gorge however most the the area will see gusts capped in the 15 to 20 mph range over the next couple of days. Trends for a compact shortwave riding through the base of the trough Thursday into early Friday are leading to some low thunder probabilities across the higher terrain on Thursday (mostly about a 10% chance or less based on NBM Conus ensemble members). Heat Risk will remain the Minor category though most of the period, although by Friday warmer temperatures in the eastern mountains foothills and north central Oregon appear to drive the HeatRisk into the Moderate category, which can affect those sensitive to heat without cooling or hydration as well as some health systems and industries. The area of smoke will continue to linger downwind of ongoing fires from central Oregon across the eastern mountains. Air Quality Advisories have been issues in accordance with DEQ alerts though the midday Wednesday as recent AQIs were int eh 100 to 171 range. By Saturday The upper low and mean tough over the BC coast is shown to accelerate inland though Saturday night, flattening (zonal) out and increasing the height gradient aloft with a frontal passage and significant increase in westerly surface winds impacting fire risk levels

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

VFR conditions prevail with the exception of PDT experiencing MVFR due to haze/smoke in the general area. Pinpointing sub-VFR due to smoke/haze for other TAF sites has proved to be a bit challenging, but it still in general persist in the area. The question is if it will get down to the surface and accumulate enough to drop visibilities. For now, a small chance (5 to 15%) is dedicated to all sites for temporary reduced visibilities due to smoke. Otherwise, the other impact will be from the upcoming cold front that will bring breezy conditions with 20 to 30 knot gusts throughout the day Tuesday.

FIRE WEATHER

Low RH is the critical element relative to fire weather, but winds will not combine at levels needed to reach a red flag criteria on anything more than a late afternoon and very spotty nature This week. A more significant impact to the fire risk levels will arrive Saturday as a frontal passage increases wind speeds on a widespread basis.

Preliminary Point Temps/PoPs

PDT 57 87 55 87 / 0 0 0 0 ALW 63 90 60 89 / 0 0 0 0 PSC 61 92 57 90 / 0 0 0 0 YKM 59 89 56 89 / 0 0 0 0 HRI 61 90 58 90 / 0 0 0 0 ELN 56 81 52 84 / 0 0 0 0 RDM 50 87 49 88 / 0 0 0 0 LGD 56 89 55 90 / 0 0 0 0 GCD 54 92 54 93 / 0 0 0 0 DLS 62 84 59 87 / 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.