textproduct: Pendleton

KEY MESSAGES

- Patchy frost/freezing temperatures possible in Central Oregon and Kittitas Valley tonight.

- Warmer high temperatures through the week with zonal/split flow aloft.

- Showers (50-70% chance) developing along the Cascades Tuesday with a shortwave passing through British Colombia.

DISCUSSION

Radar advertising light returns across as a low pressure system centered around northern California advects moisture across the Blue and Eastern Mountains through this afternoon. The exiting of the low pressure system will bring calm, clear conditions across the region overnight, allowing cooler lows tonight with the possibility of freezing temperatures in the Kittitas Valley, Central Oregon, and other low sheltered valleys. Confidence isn't too great (only 20-40% chance) that freezing temperatures will linger in these parts long enough to warrant freeze warnings. It's possible with a re-assessment later today/tonight that we might issue freeze warnings for all or some of these areas based on if guidance is still aligned or not. For now, we decided to hold off as of now.

The low will continue to push off to the east through the remainder of the day, allowing more zonal flow to take place as a trough digs down from British Colombia and a ridge pushes east just underneath it. This set-up will allow moderate to heavy showers to develop in the Cascade region (mostly on the Washington state side) through Tuesday, with the maximum potential located around Snoqualmie. Decent chance (50-70%) we'll see wetting rains around the Snoqualmie area with QPF's advertising up to a half an inch possible through Tuesday and Wednesday.

As we head later into the week, guidance is in good agreement (80-90% chance) that the ridge just offshore will continue to push east, dropping off PoP's on the later half of the week. The ridge axis will amplify heading onshore bringing warmer weather with highs into the low to high 70s through the week, with calmer winds. Although timing is a bit rough with guidance, the general picture is the same that we'll be in a mostly dry pattern with calm to elevated winds through the week.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Light and variable winds under 6 knots are the most likely winds overnight before mixing develops on Monday and more westerly momentum develops through the Columbia River Gorge. DLS can see west winds gusting to near 26 knots by late afternoon. Otherwise, expectations for VFR conditions is of at least an 80% confidence level though the TAF period at all terminals.

Preliminary Point Temps/PoPs

PDT 39 70 44 75 / 0 0 0 0 ALW 45 71 51 75 / 0 0 0 0 PSC 40 75 45 77 / 0 0 0 0 YKM 43 73 46 73 / 0 0 0 0 HRI 39 74 48 76 / 0 0 0 0 ELN 37 68 43 64 / 0 0 0 20 RDM 31 71 36 75 / 0 0 0 0 LGD 39 71 39 75 / 10 0 0 0 GCD 39 72 40 76 / 0 0 0 0 DLS 46 76 48 73 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...None. OR...None.