textproduct: Pendleton

KEY MESSAGES

- Localized areas of frost and freeze overnight tonight

- Above average temperatures likely on Friday, with breezy conditions in the Blue Mountains and Grande Ronde Valley

- Chances for rain return early next week.

DISCUSSION

Quiet weather today with some mid-upper level clouds starting to come into the region from the northwest, as shown by visible satellite imagery. Current water vapor imagery and upper air observations show a cutoff low over the Nevada-Utah border and a ridge over the Eastern Pacific. As this ridge continues to move east, it will move into the region during the next day or two.

As a result of the ridging through Friday, temperatures will gradually increase throughout the week. Temperatures overnight tonight will be a few degrees warmer than last night, but areas of frost and freeze are still locally (in colder prone locations) possible (20-40%) in lower elevations. However, widespread freezing temperatures appear unlikely (<10%). As a result, a freeze warning is not currently expected for areas still eligible. Towards the end of the week, as the next system approaches, highs on Friday will reach the mid 70s to low 80s for lower elevations and the low 60s to 70s for higher elevations, which is around 10-20 degrees above normal (Confidence 90%). Additionally, there is evidence in the longer range CAMS (i.e. the RRFS, experimental MPAS-RRFS, and University of Washington WRF) that suggest the development of breezy conditions across the Blue Mountains and Grande Ronde Valley on Friday. Current guidance suggests wind gusts in the 30-40 mph range. However, the exact magnitude will become better refined as the event comes into range for more of the CAMS.

After Friday, models are in somewhat good agreement about the presence of two troughs coming through the region. The first is a weak shortwave trough that will come through the Northwest during the weekend. The timing and amplitude does have some uncertainty but there is good agreement that the precip will be confined to the Cascades. The second trough appears to be a deeper trough that will come through sometime towards the start of next week. LREF cluster EOF's show that timing is currently the largest source of uncertainty followed by the amplitude of the trough. Despite the uncertainty, models suggest that this will be the next best chance of seeing rain for most of the area, with NBM probabilities of measurable rain (>0.01 in) around 70% in the Blue Mountains and 25-50% in the lower elevations. Garty/26

Preliminary Point Temps/PoPs

PDT 64 36 68 37 / 0 0 0 0 ALW 65 41 69 41 / 0 0 0 0 PSC 67 34 71 36 / 0 0 0 0 YKM 65 39 70 41 / 0 0 0 0 HRI 66 36 70 38 / 0 0 0 0 ELN 62 35 67 37 / 0 0 0 0 RDM 66 27 69 30 / 0 0 0 0 LGD 63 31 68 34 / 0 0 0 0 GCD 64 33 70 37 / 0 0 0 0 DLS 70 41 74 45 / 0 0 0 0

Preliminary Point Temps/PoPs

PDT 34 68 36 69 / 0 0 0 0 ALW 41 68 39 70 / 0 0 0 0 PSC 36 70 37 71 / 0 0 0 0 YKM 42 70 43 70 / 0 10 0 0 HRI 38 69 39 70 / 0 0 0 0 ELN 38 67 38 66 / 0 10 0 0 RDM 31 69 33 74 / 0 0 0 0 LGD 33 67 35 70 / 0 0 0 0 GCD 32 68 35 75 / 0 0 0 0 DLS 43 74 46 74 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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