textproduct: Pendleton

KEY MESSAGES

- Upper level high pressure over the region will continue to bring dry conditions and above normal temperatures through Thursday

- Locally breezy winds through the Cascade Gaps Monday afternoon

- Growing potential for mountain showers Friday into next weekend

DISCUSSION

Much like yesterday, little to talk about on visible satellite this afternoon as high pressure aloft is producing clear skies over much of the PacNW.

Upper level ridging continues to sit over the PacNW today, with ridging expected to remain overhead through at least Thursday (confidence 85-90%). Tomorrow 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 80-85%). Tuesday through Thursday, ensemble guidance continues to be in great agreement of upper level ridging building back over the PacNW then amplifying poleward. By Friday, ensemble guidance is in good agreement that the upper level ridge will be pushed out of the region by an upper level trough. However there is disagreement between the ECMWF and GFS ensemble members in timing, position, and strength of the incoming upper trough through Saturday.

Temperatures will continue on a gradual increase today, with afternoon temperatures peaking in the upper 70s to mid 80s tomorrow (confidence 80-90%). 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 tomorrow afternoon, 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 passage to the north. As mentioned earlier, uncertainty in the timing/strength of a trough passage Friday and Saturday invites low confidence (15-20%) in extent, intensity, and timing of showers during this period. However, there is moderate confidence (50-60%) that the Cascade crest/east slopes will see showers sometime during this period with lower confidence (25-35%) in the northern Blues seeing any precipitation as well. Otherwise, the incoming upper trough will also produce breezy west winds through the Cascade Gaps and lower elevations (confidence 55-60%), but low confidence (25-30%) in forecast timing/strength of winds for Friday and Saturday. Lawhorn/82

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

VFR conditions to prevail through the period. Winds will be light and diurnally driven. Lawhorn/82

Preliminary Point Temps/PoPs

PDT 50 83 47 80 / 0 0 0 0 ALW 56 83 54 81 / 0 0 0 0 PSC 49 84 49 80 / 0 0 0 0 YKM 52 83 50 80 / 0 0 0 0 HRI 49 84 49 81 / 0 0 0 0 ELN 50 78 48 77 / 0 0 0 0 RDM 48 86 42 84 / 0 0 0 0 LGD 52 86 48 84 / 0 0 0 0 GCD 53 87 49 87 / 0 0 0 0 DLS 55 86 52 84 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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