textproduct: Pendleton

KEY MESSAGES

1. Heavy snow Tuesday night into Friday morning

WINTER STORM WARNING IN EFFECT 5 PM TUESDAY NIGHT THROUGH 5 AM FRIDAY MORNING

2. Moderate snow continuing through this evening

WINTER WEATHER ADVISORY FOR LOWER SLOPES OF THE E. WA CASCADES and THE NORTHERN BLUES OF WASHIGNTON AM THIS MORNING TO 8 PM PDT THIS EVENING ABOVE 3000 FEET and WINTER WEATHER ADVISORY FOR THE LOWER SLOPES OF THE OR CASCADES REMAINS IN EFFECT UNTIL 5 PM PDT THIS AFTERNOON ABOVE 4500 FEET

3. Breezy winds will persist through the week

HIGH WIND WARNING IN EFFECT 5 PM WEDNESDAY THROUGH 11 AM THURSDAY

DISCUSSION

Current radar shows returns moving across the Cascades over Snoqualmie Pass through Hyak and into Easton. Current webcams shows moderate snowfall occurring through the aforementioned areas.Ground observations at Bumping Ridge shows 9 inches of snowfall and Hyak has reported 7.5 inches and 12 inches just north of Easton since this morning. A short lull in moderate/heavy precipitation will occur between now and early Tuesday morning before the cold front moves across the WA Cascades causing the snow levels to drop back down to below 2000 feet. A rain/snow mix will continue during the brief lull with 40-60% confidence only 2 inches will accumulate ahead of the next round. The next surge from this system will bring expected amounts of 1-2 additional feet with 60-80% of the NBM raw ensembles in agreement.

Winter weather advisories are in effect through 5 PM for the lower east slopes of the OR Cascades through 5 PM for an additional snow accumulation of 2 to 5 more inches on top of the recorded 8 inches since 10 AM this morning (60-80% confidence). A winter weather advisory is also in effect for the lower Slopes of the Eastern Washington Cascades Crest for an additional 2-4 inches of snow accumulation through 8 PM this evening. NBM raw ensembles show 60- 80% confidence in another 2-4 inches for both the OR Cascades and 40-60% confidence in 3-5 inches for the Northern Blues.

A high winds warning will go into effect after 5 PM Wednesday night and remain through 11 AM Thursday for the: Lower Columbia Basin of Oregon-Foothills of the Northern Blue Mountains of Oregon-Foothills of the Southern Blue Mountains of Oregon-North Central Oregon-Lower Columbia Basin of Washington-Foothills of the Blue Mountains of Washington. Southwest winds of 25 to 35 mph sustained with gusts up to 60 mph expected with 70-80% confidence. 90

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

VFR conditions to prevail through the period. AN atmospheric river is impacting the region bringing rain to DLS/PDT/YKM/ALW, with rain ending later this evening at sites PDT/ALW. Winds will increase at all sites during the period, with peak winds 20-30kts and gusts 30-40kts at sites PDT/RDM/BDN/ALW after 5 PM. PSC is expected to see wind gusts to 45 kts (50-70% confidence) with gusts to 55 kts possible (20-30% confidence). Winds at sites DLS/YKM will be 15-20kts with gusts up to 30kts, developing after 23Z and persisting through the end of the period. There is a chance (20-35%) that low level wind shear may impact all sites later this evening and overnight. That said, there was high enough confidence to include wind shear at site ALW after 03Z.

Preliminary Point Temps/PoPs

PDT 43 53 38 52 / 50 80 90 80 ALW 44 53 39 50 / 80 80 90 90 PSC 46 57 39 54 / 30 40 60 70 YKM 39 52 33 52 / 80 50 50 70 HRI 46 55 40 53 / 40 60 70 70 ELN 35 44 32 44 / 90 60 60 70 RDM 39 56 39 57 / 30 50 40 30 LGD 41 48 41 53 / 90 100 100 90 GCD 43 53 43 57 / 30 70 70 50 DLS 42 50 40 53 / 90 90 80 80

PDT WATCHES/WARNINGS/ADVISORIES

WA...High Wind Warning from 5 PM this afternoon to 11 AM PDT Thursday for WAZ026-028-029-521. Winter Weather Advisory until 8 PM PDT this evening for WAZ030- 523. Winter Storm Warning until 5 AM PDT Friday for WAZ522. OR...High Wind Warning from 5 PM this afternoon to 11 AM PDT Thursday for ORZ044-507-508-510. Winter Weather Advisory until 5 PM PDT this afternoon for ORZ509.