textproduct: Pendleton

KEY MESSAGES

- Patchy fog with low stratus less than 1000 feet in many portions of the lower elevation areas continue through tonight.

- Active weather resumes later today as an area of low pressure pulls through the region and brings periods of moderate to heavy showers, high mountain snow, and breezy to windy conditions.

- Uncertainty going into next week with the upper level pattern and overall impacts to the area.

DISCUSSION

Surface observations through the Columbia Basin, valleys, and foothills read out visibility at less than a mile coupled with stratus decks less than 1000 feet in some parts associated with fog. Surface observations show that fog has pushed further south than last night in parts of Central Oregon near Madras, but confidence has decreased (15-25% chance) we'll see some fog push into the Redmond/Bend area, although less sure that it'll be as dense as what we've seen in the valley/basin. Dense fog and low stratus decks at already impacted areas will continue through the morning hours before being lifted from warmer temperatures. On the radar side, reflectivity is showing a large swath of precipitation located west of the Cascades, impacting the coastal parts of Oregon and Washington state. This area of precip will continue pushing east through today and eventually makes it way over our area by the later morning to early afternoon hours.

As that precip continues to push west to east, it will bring a slew of moisture with moderate to heavy shower embedded with breezy to windy conditions through the day. As the low pushes through, it'll bring low to medium chances (20-40%) in the lower elevation areas (including Central OR) and high chances (>80%) of at least a quarter inch of precipitation in a 24-hour period through Saturday. Snow levels stay steady through Friday night at around 6500 to 7000 feet, leaving it a mostly warm system. As the area of low pressure pushes closer, pressure gradients tighten with a 45-55 knot 850mb jet developing over Central Oregon through the eastern mountains. As a result winds will be as strong as 45-55 mph (70-90% confidence) as they mix down through many areas of Central and northeast Oregon.

By Saturday, guidance is in good agreement that a transient ridge will move into the area, allowing a break in the weather as dry conditions briefly come back (except for some Cascade mountain rain and snow showers). A cooler air mass will pull-in (>85% chance) and drop snow levels down to 5000-5500 feet by Saturday night, which will bring light to moderate snow showers in the crests (30-50% confidence). Going forward, another shortwave pulls through early next week with uncertainty in the timing/strength along with the impacts expected. According to clusters, 39% of members brings a drier solution with a weaker ridge set-up while the remaining members bring a more neutral/slightly stronger set-up. Plenty of time to monitor this evolving forecast, but do not see significant impacts at this time.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

VFR conditions initiate for RDM/BDN/YKM, with the rest of the sites starting at MVFR or lower due to dense fog and low level cloud decks. Conditions improve going into the later morning hours with visibility, but moderate to heavy showers move into the area through much of the later morning to late afternoon hours. Can see additional MVFR or lower conditions developing (up to 25% for each site) with VIS and CIGs degrading from where the heaviest showers develop. Winds will be breezy with gusts up to 30 to 40 knots (except DLS and YKM) through the early evening. Additionally, fog formation in BDN/RDM down to IFR levels is low (15-25% chance) with increased confidence the stratus will reach down further in central OR.

Preliminary Point Temps/PoPs

PDT 68 41 61 42 / 0 50 0 0 ALW 67 45 58 46 / 0 80 10 0 PSC 62 39 62 39 / 20 50 0 10 YKM 57 37 57 38 / 70 60 0 40 HRI 66 39 61 41 / 10 50 0 10 ELN 54 32 51 34 / 50 60 0 40 RDM 58 33 53 37 / 90 10 10 20 LGD 61 38 55 38 / 0 80 10 0 GCD 62 35 53 36 / 30 80 10 0 DLS 55 40 56 42 / 80 40 30 50

PDT WATCHES/WARNINGS/ADVISORIES

WA...Wind Advisory from 8 AM this morning to 7 PM PST this evening for WAZ029. Dense Fog Advisory until 9 AM PST this morning for WAZ028-029. OR...Wind Advisory from 8 AM this morning to 7 PM PST this evening for ORZ049-050-507-508. Dense Fog Advisory until 9 AM PST this morning for ORZ507. Wind Advisory until 4 PM PST this afternoon for ORZ510-511.