textproduct: Pendleton

KEY MESSAGES

- Patchy dense fog through the area tonight and tomorrow night in valleys and gaps.

- An overhead ridge is allowing dry conditions to persist through overnight Thursday.

- Active weather re-develops Friday (90% confidence) through the weekend with moderate to heavy showers with breezy to windy conditions embedded.

DISCUSSION

Night physics satellite shows areas of patchy dense fog across valley areas that include the Columbia Gorge and Yakima Valley (especially near Sunnyside). Fog will stick around through the rest of the overnight hours and into the late morning before mixing out from daytime heating. Low to medium confidence (20-40%) that fog redevelops tomorrow night and more or so the same areas we've seen fog tonight.

The overhead ridge currently in-place will keep substance in- place and will also allow conditions to remain dry through the overnight hours Thursday. Breezy to locally windy south and south-eastern winds develop under this blocking pattern. Seasonally warm temperatures 10-15 degrees above normal with the greatest chance of warm temperatures along Central OR (>85% chance) and lower Columbia Basin (50-70% chance).

Ensemble guidance into the weekend sets-up a synoptic pattern in the mid-level for active weather to develop (>90% confidence) another system. Guidance remain fairly uncertain going into Friday & the weekend with a cut-off low/shortwave developing off the coast. High PoP's return as well as breezy wind to locally windy conditions (70-80% confidence) across the area. Will see the probability of wind advisory highlights (30-50% chance) over the next 48-hours, especially near Central Oregon with breezy to windy conditions developing Friday and Saturday. At the 500 hPa level, a 70-80 knot streak will move over the Oregon/California border Friday morning (40-50% chance). Will need to see if winds can mix down to the surface with it moving over the morning hours gives less confidence it will do so. Regardless, breezy and windy 25 to 35 mph winds with gusts up to 40 to 50 mph is possible through parts of Central Oregon through the Blue Mountains.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

DLS: MVFR conditions but fog is sloshing around so a tempo group for low CIGs has been put in. PDT/YKM/ALW: All are LIFR due to either 1/4SM or VV002 CIGs. PSC: IFR due to mainly CIGs with 3 SM. This will be the course through much of the period with only brief times of VFR at all aforementioned sites. Some sites will clear after 22Z briefly before FG lowers the sites back to LIFR between 05-09Z.

BDN/RDM: VFR conditions prevail through the period with clear and dry weather through the next 24-hours. Winds will generally be light with most sustained winds less than 12 knots. Otherwise, no CIG or VIS issues anticipated through the Central OR sites.

Preliminary Point Temps/PoPs

PDT 66 37 61 41 / 0 0 0 0 ALW 65 43 61 47 / 0 0 0 0 PSC 58 36 55 34 / 0 0 0 0 YKM 60 37 58 36 / 0 0 0 0 HRI 60 35 56 36 / 0 0 0 0 ELN 56 35 55 33 / 0 0 0 0 RDM 72 35 69 43 / 0 0 0 0 LGD 64 44 62 43 / 0 0 0 0 GCD 70 37 68 38 / 0 0 0 0 DLS 61 42 58 40 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Dense Fog Advisory until 10 AM PST this morning for WAZ026-027. OR...None.