textproduct: Pendleton

KEY MESSAGES

1. Mountain rain will persist through Friday before transitioning to snow

2. Above seasonal average temperatures remain through Friday

3. A system will bring temperatures back to seasonal average Saturday

DISCUSSION

Current radar shows a few returns over the WA Cascades as the remnants of the atmospheric river remain over the area. Current ground observations show that the last hour these returns have only put down between 0.01-0.02 inches of rain. Rain is expected to continue over the mountains through Friday with rain accumulations nearing 0.4-0.8 inches through 5 AM Friday (70-80% confidence). Saturday snow levels will begin to drop bringing cooler temperatures back to the mountains with light mountain snow.

Models show an upper level ridge still over the region. This is what is bringing the above average seasonal temperatures. In house comparisons for temperatures shows that temperatures both Thursday and Friday are anywhere between 20-25 degrees above normal with even the higher elevations seeing above average temperatures. Models show the ridge to remain in place through at least Friday ahead of a pattern change. Temperatures will remain above seasonal average through Friday with temperatures remaining in the low to mid 70s across the region with 90-100% of the NBM raw ensembles in agreement. Friday temperatures will drop only 1-2 degrees with temperatures remaining in the low to mid 70s for much of the region with again 90-100% of the raw ensembles in agreement.

Friday night into Saturday models are in good agreement with a weak upper level trough sweeping into the region with mostly zonal flow. NBM shows snow levels to begin to decrease as the system moves across and temperatures will decrease to near seasonal average. Mountain precipitation is expected with this system with very light (0.01-0.02 inches) snow accumulations expected (80-90% confidence)long the crests. Temperatures will decrease by nearly 20 degrees Saturday with localized highs in the low 60s in the Basin and mid to upper 50s elsewhere (60-80% confidence). 90

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

VFR conditions prevail with mostly dry conditions across all airport sites. Main issue will be some locally breezy winds at BDN/RDM and, to a lesser extent, PSC. Expecting breezy 20-30 mph gusts in the Central Oregon sites in the late morning/early afternoon hours. PSC is not expected to be as windy at 10-20mph developing in the same time frame. Otherwise, VIS and CIG will remain in the VFR category.

FIRE WEATHER

An SPS is out for elevated fire weather conditions for Ochoco-John Day Highlands and central OR. A strong ridge of high pressure has lead to well above average seasonal temperatures as well as very low relative humidities (80-90% confidence)for portions of central OR and the eastern mountains. Additionally, diurnal winds have the capabilities of reaching 20 to 30 mph gusts (50-70% confidence). The combination of dry conditions and elevated winds can lead to rapid fire spread. 90

Preliminary Point Temps/PoPs

PDT 75 50 75 45 / 0 10 0 30 ALW 73 55 74 48 / 10 10 10 50 PSC 75 53 75 48 / 10 10 0 20 YKM 73 49 71 39 / 10 20 20 10 HRI 76 51 76 48 / 0 10 0 20 ELN 64 45 62 37 / 20 40 40 10 RDM 78 44 76 41 / 0 0 0 10 LGD 76 48 77 45 / 0 0 0 40 GCD 78 47 78 45 / 0 0 0 10 DLS 74 51 69 45 / 10 20 20 30

PDT WATCHES/WARNINGS/ADVISORIES

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