textproduct: Pendleton

KEY MESSAGES

- Periods of dense fog for the WA Columbia Basin & Kittitas area continues through tomorrow.

- Shortwave tomorrow late morning/early afternoon will help temporary escape the fog pattern.

- Possible wet pattern next weekend with a breakdown of the ridge, brings rain and mountain wintry mix.

DISCUSSION

An upper level ridge continues to bring substance over the region, allowing fog to form through the valley, especially in sheltered areas across south-central Washington. We'll continue to have this foggy pattern through tomorrow, until a shortwave propagates through the region tomorrow. A weak cold front embedded with the shortwave will bring light mountain rain/snow mix through the Cascades and Blue Mountains tomorrow morning and through the afternoon, along with very light rain for parts of the Columbia Basin. QPF doesn't pick-up in most of the Columbia Basin where PoPs are at least 15%, suggesting any amount of rainfall will be fairly little if any.

We re-enter a dry pattern by mid-week with the ridge amplifying over the PacNW, bringing back chances for more fog and stratus formation going through the later part of this week. Things become a bit more uncertain as we head into next weekend, with the overall consciouses from the EURO and GFS ensembles, is too break the ridge down and bring a more activate weather pattern heading into the weekend. Timing is a bit uncertain as too when the second shortwave moves through, but regardless, there is a medium to high chance (50-70 percent chance) of the pattern switching to a more unstable air mass going through next weekend, bringing increase PoPs.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

The fog will remain lingering over KALW with VSBY of 1/2SM or less through evening hours and possibly overnight. It is recommended to wary of the fog sloshing around KALW, causing oscillating VSBYs. While it has been lifted for KDLS, the fog could return overnight into late Sunday morning with KPSC joining in around that time. Other than that, the other sites (KPDT/KRDM/KBDN) will be VFR throughout this period, though KBDN may have breezy winds around late Sunday morning. Low CIGs (BKN-OVC at 001-015) will persist for KDLS/KPSC through Sunday whereas KYKM/KALW might have low CIGs lingering through the day Sunday. Rain could develop for most sites (KDLS/KRDM/KBDN/KYKM/KALW) Sunday morning through afternoon, but with a slight chance (<30%). Didn't mention it in the TAFs for KPDT/KPSC since confidence was too low (<10%). Feaster/97

Preliminary Point Temps/PoPs

PDT 34 51 35 55 / 0 20 0 10 ALW 36 50 38 55 / 0 30 10 10 PSC 34 52 34 51 / 0 20 0 10 YKM 34 49 32 49 / 0 40 0 20 HRI 34 52 34 53 / 0 10 0 10 ELN 33 44 31 44 / 0 60 10 30 RDM 33 52 28 54 / 0 20 0 0 LGD 38 52 32 51 / 0 10 10 10 GCD 36 52 31 51 / 0 10 0 0 DLS 39 52 39 51 / 0 60 10 20

PDT WATCHES/WARNINGS/ADVISORIES

WA...Dense Fog Advisory until 6 PM PST this evening for WAZ026. OR...None.