textproduct: Pendleton

KEY MESSAGES

- Dry conditions and warming temperatures into the middle of the week

- Mountain showers and thunderstorms return Wednesday, then potentially Friday into the weekend

DISCUSSION

Today through Early Wednesday: Water Vapor satellite imagery tonight shows the upper trough over the northern Rockies, with nighttime satellite imagery showing high cloud decks over far northeast OR and southeast WA.

The trend amongst ensemble and deterministic guidance today is for a weak, broad area of low pressure to develop over the northern Rockies with a ridge building offshore the PacNW. Tuesday through early Wednesday, the ridge will slide over the PacNW, bringing temperatures into the upper 70s to mid 80s in the lower elevations. Otherwise, conditions will remain dry with locally breezy afternoon winds.

Wednesday through Saturday: Ensemble guidance is in good agreement of an upper shortwave trough sliding across the PacNW Wednesday, though there remains some uncertainty in timing and strength of this feature. While the main consensus is for a return of mountain showers and breezy lowland winds into Thursday morning, some solutions (22% of members) favor a stronger shortwave that will bring area wide showers that will persist through Thursday afternoon. Otherwise, this pattern would also favor a return of afternoon/evening isolated thunderstorms over the mountain areas Wednesday.

Dry conditions will return to the area after the shortwave exit Thursday, but breezy to locally gusty Cascade gap winds will persist(confidence 45-60%). Ensemble guidance is in agreement that an upper low will arrive offshore the PacNW Friday then push inland sometime Saturday, though there is uncertainty in timing. That said, the trend amongst ensembles is that the upper low will produce showers across the Cascades Friday afternoon and overnight, with showers spreading to the eastern mountains sometime Saturday (confidence 40-60%). Otherwise, the upper low arrival and subsequent passage will produce breezy winds across the lower the elevations (confidence 45-65%). Lawhorn/82

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

VFR conditions to prevail through the period. Winds will be light, 12kts or less, and diurnally/terrain driven through the period. Lawhorn/82

Preliminary Point Temps/PoPs

PDT 71 45 76 48 / 0 0 0 0 ALW 72 50 76 52 / 0 0 0 0 PSC 77 48 80 51 / 0 0 0 0 YKM 77 48 80 52 / 0 0 0 0 HRI 75 47 79 51 / 0 0 0 0 ELN 71 45 75 49 / 0 0 0 0 RDM 67 34 73 41 / 0 0 0 0 LGD 68 41 72 44 / 0 0 0 0 GCD 70 37 75 42 / 0 0 0 0 DLS 76 49 83 57 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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