textproduct: Pendleton

KEY MESSAGES

- Moderate to Heavy snow expected across the Washington Cascades through Thursday afternoon. Possible blowing snow embedded with breezy winds.

- Winds increase across the Washington Basin going into the early work week.

- Moderate to heavy mountain snow will continue through at least mid-next week, bringing heavy accumulations across the mountains.

DISCUSSION

Radar and satellite shows dry conditions persist in the area, with some mid to high level clouds near the Wallowas and Foothills of the Northern Blues in Washington. A couple of shortwaves in the 500 mb level will bring a few rain showers in the Washington Cascades later this afternoon and into the evening hours. More moderate to heavy rain showers will develop in the morning hours of Sunday through the afternoon. Six-hour QPF amounts range up to a tenth of an inch through early Sunday morning, then become heavier at .50" to .75" (70-90% confidence). A passing cold front will pass in the late morning to afternoon hours Sunday where snow levels in the Cascade region will quickly drop from 7000 feet, down to 1500 to 2000 feet by the evening hours. Rain will quickly transition to snow with the cold front passage in the Washington Cascades, then gradually to the Oregon Cascades later in the evening. Breezy to locally windy conditions will emerge across the Washington Cascades with 30-40 mph gusts Sunday morning through the evening hours (70-90% confidence).

A more zonal pattern will emerge Monday, bringing more moderate snow showers across the Cascades (with a more heavier emphasis on the Washington Cascades). A Winter Weather Advisory is issued for the WA Cascades for Monday morning through Tuesday afternoon with 8-14 inches expected (70-90% confidence). Things become more active mid-week with IVT chances of >250 kg/(ms) increasing to >80% chances. NBM re-animates snow fall amounts after late Tuesday afternoon with three day snow totals showing moderate to heavy snow rates across the Cascades with heavier amounts in the Washington Cascades. NBM currently predicts 2 to 4 feet in many areas of the slopes of the eastern WA Cascades (60-80% confidence for higher crests areas and 30-50% chance for the pass levels). With that, additional winter weather highlights are possible as we get closer to the event after the current advisory.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

VFR conditions will prevail through the forecasted period. CIGs will be 10-25kft through the day with some TAF sites clearing to SKC. The shortwave disturbance will continue to bring elevated winds across TAF sites DLS/ALW/PDT/PSC ranging from 15-20kts with gusts nearing 30 kts through the period. 90

Preliminary Point Temps/PoPs

PDT 64 43 62 33 / 20 0 10 50 ALW 64 47 62 34 / 20 0 20 60 PSC 69 47 66 34 / 10 0 10 10 YKM 66 40 62 30 / 10 0 10 10 HRI 67 46 65 34 / 10 0 10 30 ELN 58 42 54 29 / 10 10 30 20 RDM 62 33 59 31 / 10 0 0 10 LGD 61 39 61 33 / 30 10 10 60 GCD 58 36 61 35 / 20 0 0 30 DLS 63 46 60 36 / 20 10 30 40

PDT WATCHES/WARNINGS/ADVISORIES

WA...Wind Advisory from 8 AM to 9 PM PST Sunday for WAZ026-028-029. Winter Weather Advisory from 5 AM Monday to 5 PM PST Tuesday for WAZ522. OR...None.