textproduct: Pendleton

KEY MESSAGES

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

- Breezy conditions in the Columbia River Gorge and Kittitas Valley on Saturday

- Chances for rain early next week.

DISCUSSION

The weather today has been generally quiet with the only note being a band of light rain that has been moving through western portions of the CWA. That band of light rain has largely dissipated and visible satellite imagery shows clear to mostly clear skies moving into the region from the north. Mid-level water vapor imagery and upper air soundings show that an upper level ridge has started building into the region.

Latest model guidance shows that ridging will be in place through Friday before a shortwave trough comes through the region. As a result, temperatures will increase throughout the week, with the hottest day being on Friday where temperatures will likely be in the mid 70s to low 80s for lower elevations and in the low 60s to low 70s in higher elevations, which is around 10-20 degrees above normal (90% confidence). Of additional note, models are still indicating that breezy conditions will likely set up in the Blue Mountains and the Grande Ronde Valley Friday morning (Confidence 80%). This is a result of a somewhat large pressure gradient setting up in the Blue Mountains. The Surface Pressure Gradient Tool developed by the SPC shows that the NAM and SREF have a pressure gradient of 4-7 mb between Baker City and Meacham. The mean wind gusts off the REFS shows wind gusts up to 45-50 mph in the Blue Mountains and 35-40 mph in the Grande Ronde valley on Friday morning.

After Friday, model guidance shows that two systems will come through the region. The first is a shortwave trough that will move through the Northwest during the day Saturday into Sunday morning. Currently, rain associated with the system looks confined to the higher terrain in the Cascades. In addition, as the system comes through, the winds on Saturday should shift to being from the southwest. As a result, breezier conditions will likely (80% confidence) develop on Saturday mainly in areas with channeling effects (i.e. Columbia River Gorge and Kittitas Valley). Current NBM guidance suggests that the winds will remain below wind advisory criteria (wind gusts >45mph) with a probability of meeting advisory criteria of <10%.

The second trough has more uncertainty with it but models bring it through early next week. This trough looks to be the next best chance of rain. The latest NBM suggests a 50% chance of receiving measurable rain (>0.01 in) in the Blue Mountains and a 0-25% chance in the lower elevations during the day on Tuesday. With that being said, this chance for rain has dropped substantially compared to a run of the NBM 24 hours ago, which had probs of 75% and 25-50% chance of measurable rain for the higher and lower elevations respectively. This change is due to a large shift in many of the models which causes the trough to dig farther south and form a cutoff over California. However, this system still has a large amount of uncertainty associated with it as illustrated by the LREF clusters. LREF cluster EOF's show that timing is the leading source of uncertainty within the ensemble but there is still some uncertainty regarding the amplitude of the trough. Should the deeper trough trend continue, most areas would see little to no rain, while if the models trend back north, there will be a larger chance for rain. 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 38 68 38 74 / 0 0 0 0 ALW 40 69 44 75 / 0 0 0 0 PSC 37 72 37 70 / 0 0 0 0 YKM 43 70 41 69 / 0 0 0 0 HRI 39 69 37 71 / 0 0 0 0 ELN 40 66 38 66 / 0 0 0 0 RDM 31 74 33 80 / 0 0 0 0 LGD 36 69 41 70 / 0 0 0 0 GCD 36 75 39 76 / 0 0 0 0 DLS 46 74 45 75 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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