textproduct: Pendleton

KEY MESSAGES

- Periodic light mountain showers through Tuesday

- Slight chance of isolated thunderstorms this afternoon over northeast OR mountains, with low chance over the WA Cascades

- Dry and warming trend through the remainder of the week

DISCUSSION

Today through Tuesday: Satellite imagery this early morning shows cloudy conditions across the OR half of the forecast area, while scattered mid level cloud decks are across portions of southeast WA. Meanwhile, radar shows widely scattered light showers across southeast WA, while surface observations indicate showers are impacting portions of central OR at this time.

Today, the upper trough over the region will be pulled south and east by a shortwave diving down northerly flow aloft. By mid- morning, scattered shower activity will be limited to the higher peaks/crests of the mountains in northeast OR, with a slight chance (15-20%) of isolated thunderstorms forming in this area by the early afternoon. There is a low chance (~10%) that an isolated shower/thunderstorm may develop along the WA Cascade crest this afternoon.

Monday into Tuesday, the PacNW will come under the influence of an upper ridge developing offshore, with the region under a northwest flow aloft. Weak shortwaves will slide down the northwesterly flow aloft both days, which will bring slight chances (10-15%) of showers to the WA Cascades, Blues and Wallowas. Otherwise, the remainder of the forecast area will remain dry with a gradual warming trend, and diurnally driven west to northwest winds through the Cascade gaps.

Wednesday through Saturday: There remains good agreement amongst ensemble cluster guidance in the region remaining under the influence of the upper ridge offshore through Thursday afternoon. Another shortwave trough is advertised to slide down northwesterly flow Thursday evening through Friday morning, producing slight chances (10-20%) of mountain showers. After the trough exit Friday morning, the forecast area will come under the influence of the upper ridge offshore, returning to dry conditions that will persist into Saturday.

Otherwise, diurnally driven breezy winds through the Cascade gaps will continue, with strongest winds overlapping with the trough passage Thursday. A gradual warming trend in the lower elevations will result in a return of afternoon temperatures in the upper 70s to mid 80s by Thursday. Confidence in the forecast during this period is moderate (55-65%). Lawhorn/82

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Overall conditions are improving from earlier. VFR conditions prevail over the next 24-hours with 10-20 knot wind gusts. Bulk of the precip has moved out, with a few PROB30's in BDN/RDM through 08Z. Otherwise, no CIG or VIS issues expected.

Preliminary Point Temps/PoPs

PDT 64 40 70 42 / 0 10 0 0 ALW 63 44 69 46 / 10 0 0 0 PSC 71 43 75 45 / 0 0 0 0 YKM 71 42 74 44 / 0 0 0 0 HRI 69 41 73 44 / 0 0 0 0 ELN 65 39 68 40 / 0 0 0 0 RDM 60 29 68 31 / 0 0 0 0 LGD 55 33 64 36 / 10 0 0 0 GCD 55 31 65 34 / 30 0 0 0 DLS 68 44 73 45 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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