textproduct: Pendleton

KEY MESSAGES

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

- Temperatures continue to increase today, with peak temperatures expected Monday (temperatures around 15 degrees above normal)

- Mostly light winds each day, but breezy Cascade gaps winds will develop Monday afternoon

DISCUSSION

Mostly clear skies this midday across the forecast area as a zonal flow persists aloft. A weak shortwave evident in water vapor satellite imagery is sliding across southern BC today, which is expected to bring locally breezy conditions through the Cascade Gaps later this afternoon.

After today, upper level ridging will build into the PacNW from the northeast Pacific, beginning an extended period of high pressure over the region through the middle of next week (confidence 65-90%). Sunday into 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 75-80%). While high pressure persists aloft, deterministic/ensemble guidance and the tail-end of CAMs are in agreement of a weak shortwave lifting northeast into the PacNW Sunday into Monday. At this time, confidence is very low (<5%) that this feature in it's current form will produce any precipitation across the area during this two day span. Will continue to monitor as isolated convective showers could develop (10-15% chance) over higher terrain in central and east central OR with increase in moisture or instability. Tuesday through Thursday, ensemble guidance is in great agreement of upper level ridging building back over the PacNW then amplifying poleward. By Friday, ensemble guidance is in agreement of the upper level ridge breaking down, however disagreement grows in timing/strength in an approaching upper level trough.

Through Monday, temperatures will be on a gradual increase, with peak afternoon temperatures in the upper 70s to mid 80s Monday (confidence 75-80%). 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 through Thursday with light, diurnally driven winds each day. The exception will be Monday, where breezy winds (15-25 mph with gusts to around 35 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 /00Z TAFS THROUGH 00Z SUNDAY/

VFR conditions are forecast at all sites through the period. Skies will be clear to mostly clear, with passing cirrus. Winds will be light, diurnally and terrain-driven, with the exception of some breezy late afternoon and evening winds at DLS today.

Preliminary Point Temps/PoPs

PDT 47 79 48 80 / 0 0 0 0 ALW 52 82 54 80 / 0 0 0 0 PSC 49 83 49 81 / 0 0 0 0 YKM 50 79 51 81 / 0 0 0 0 HRI 50 81 49 81 / 0 0 0 0 ELN 47 75 48 78 / 0 0 0 0 RDM 42 82 42 87 / 0 0 0 0 LGD 46 83 50 88 / 0 0 0 0 GCD 47 88 49 92 / 0 0 0 0 DLS 53 83 55 85 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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