textproduct: Pendleton

KEY MESSAGES

- Upper level high pressure building over the region through next week, with dry conditions prevailing

- Temperatures begin to slowly increase today, with peak temperatures expected early next week (temperatures 5 to 15 degrees above normal)

- Light, diurnally driven winds will prevail each day

DISCUSSION

Nighttime satellite imagery tonight shows decks of cirrus moving east across the northern two-thirds of the forecast area, while mid level stratus over the Yakima/Kittitas valleys peaks through breaks in the cirrus.

Through the middle of next week, ensemble and deterministic model guidance stay in great agreement of the PacNW remaining under the influence of upper level ridging or zonal flow aloft. Through Friday night, the upper level ridge will remain quite flat over the PacNW due to separate shortwave passages through southern BC Thursday and Friday (confidence 75-90%). Meanwhile, the upper level ridge will amplify over the eastern Pacific during this period, then slide inland over the weekend (confidence 70-85%). Monday the ridge axis will push east of the PacNW as an upper trough slides into northern BC, with zonal flow developing overhead and high pressure aloft to the south (confidence 65-70%). By Tuesday through Wednesday, ensemble guidance is in great agreement of upper level ridging building back over the PacNW then amplifying poleward. Through Monday, temperatures will be on a gradual increase, with peak afternoon temperatures in the upper 70s to mid 80s Monday (confidence 65-75%). Temperatures will drop a couple degrees into Tuesday, but expect high temperatures to remain in the upper 70s to low 80s. Conditions are expected to remain dry into middle of next week with light, diurnally driven winds each day. The exception will be Monday, where breezy winds (15-20 mph with gusts to around 30 mph) will develop through the Cascade gaps as surface pressure gradients slightly strengthen in response to the upper trough passing to the north. Lawhorn/82

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

VFR conditions are very likely (90% chance or higher) for all TAF sites through the period; there is a very low (10%) chance of VSBY reductions overnight into Friday morning at RDM, with even lower chances elsewhere. Otherwise, predominantly FEW-BKN cirrus will overspread the Pacific Northwest for the next 24 hrs, with low confidence (30% or less) in some periodic mid- level stratus. Winds will be light and diurnally/terrain driven through the period.

Preliminary Point Temps/PoPs

PDT 74 47 78 47 / 0 0 0 0 ALW 75 53 79 52 / 0 0 0 0 PSC 77 47 81 49 / 0 0 0 0 YKM 74 50 80 50 / 0 0 0 0 HRI 76 48 81 50 / 0 0 0 0 ELN 69 45 75 46 / 0 0 0 0 RDM 77 42 81 42 / 0 0 0 0 LGD 76 48 81 47 / 0 0 0 0 GCD 81 47 82 47 / 0 0 0 0 DLS 80 54 83 53 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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