Marine Weather and Tide Forecast for Boardman, OR

PREV DISCUSSION
/issued 443 PM PDT Mon Apr 28 2025/

Updated for Aviation...

SHORT TERM
Today through Wednesday
With the ridge over the PacNW, warm dry conditions continue through this late afternoon.
As the shortwave trough begin clipping across the forecast area this evening into tonight, the frontal system will arrive with light showers at the WA/OR Cascades first (>35% chance) and then northern Blues including Yakima Valley and Columbia Basin (<20% chance). However with the marine stratus layer still present and tighten surface pressure gradients, locally windy conditions (25-35 mph) will remain over the Gorge, Southern Blue Mountains- Foothills, and Kittitas Valley.

Widespread showers develop tomorrow early morning as the frontal system passes through. Light QPF amounts (0.10" or less) for most of the forecast area but the northern Blues may reach up to 0.35". Wind gusts of 45 mph with sustained winds at 25-35 mph will develop at Kittitas Valley with the marine stratus layer continuing to linger and tighten surface pressure gradients, which has warranted for a Wind Advisory tomorrow from 2PM to 8PM PDT.
Otherwise, winds will remain gusty at 30-40 mph through the early evening for the Gorge and Southern Blue Mountains-Foothills (>60% chance). Later evening into night, winds will then decrease as the trough moves out of the area. By Wednesday, warm and dry conditions with light winds return as the ridge builds over the PacNW. Temperatures remain near to above normal for this term.
Feaster/97

LONG TERM
Thursday through Monday

Key Messages:

1. Isolated thunderstorms possible Friday afternoon and evening.

2. Widespread rain and mountain snow Friday afternoon into Saturday.

3. Breezy afternoon conditions Friday through Sunday.

The extended period is characterized by initial upper level ridging ahead of a significant upper level trough that will approach Friday before passing through the Pacific Northwest over the weekend. This will bring widespread rain Friday into Saturday, breezing afternoon conditions Friday onward, and cooler temperatures over the weekend.
Flow aloft from the south and an incoming upper level trough that is negatively-tilted will allow for instability to develop across Central Oregon, east slopes of the Cascades, Blue Mountain foothills, and portions of the Columbia Basin Friday afternoon and evening. The NBM and GFS both advertise CAPE values between 100-300 j/kg, with the GFS highlighting shear of 35 kts and low-level lapse rates of around 8 C/km. These parameters would allow for isolated, discrete thunderstorm cells, with the main impacts related to lightning, periods of heavy rainfall, and gusty and erratic winds.

The incoming system will allow for widespread rainfall and high elevation snow above 4500 feet to occur across Central Oregon Friday afternoon, before extending across the entire area after 5 PM. Light rain will then continue overnight and into Saturday morning as rain amounts reach into the 0.40-0.50" range across the Blue and Cascade Mountains, 0.30-0.40" through Central Oregon and the John Day Basin, 0.15-0.25" over the Blue Mountain foothills, and 0.03-0.15" across the Lower Columbia Basin. Confidence in these rain amounts is moderate (50-60%), as 69% of ensembles rain amounts are near to slightly above (0.01-0.03") the current forecast. The potential for increasing rain amounts are primarily focused along the Blue Mountains, John Day Basin, and Wallowa County, which is related to a deeper and stronger incoming upper level trough. The system will continue diving south into California Saturday, which will confine precipitation to areas along the Blue Mountains and east with highest rain amounts expected over Wallowa County and the northern Blue Mountains with 0.25-0.35" of rain likely. Additional rain amounts Saturday evening through Sunday morning will reach 0.15- 0.25" over the John Day Basin, and 0.05-0.15" across the northern Blue Mountain foothills. Confidence in these rain amounts is much less as ensemble clusters are in disagreement in how deep, strong, and broad the dropping upper level trough is as it proceeds through northern California. Upper level ridging and high pressure returns Sunday evening into Monday, but looks to struggle to extend over Wallowa county and over higher terrain of the John Day-Ochocos and Blue Mountains - keeping light rain into early Monday morning.

The approaching upper level trough Friday will erode the slowly departing ridge, tightening isobars and creating a pressure gradient along the Cascades. Breezy west-northwest sustained winds of 20-25 mph with gusts up to 40 mph will be possible across the east slopes of the Washington Cascades, Southern Blue Mountain foothills, Simcoe Highlands, and the Kittitas Valley Friday, Saturday, and Sunday during the afternoon/evening. Winds are expected be highest on Saturday, as there is a 50-70% chance of advisory-level wind gusts (45 mph or greater) across the Kittitas Valley and the Southern Blue Mountain foothills each day. Ensemble clusters are in fairly good agreement regarding winds with 59% of ensemble members hinting at slightly lower values than the forecast Saturday and Sunday. 75

AVIATION
00Z TAFS
VFR conditions are expected through the TAF period. RA is expected mainly at PDT and ALW For a time Tuesday morning. Otherwise, the main concern will be gusty winds through the evening at DLS, PDT, RDM and ALW. Winds will gust again on Tuesday at DLS, PDT, ALW and PSC. Winds will gust mainly in the 20 to 25 kt range.

PRELIMINARY POINT TEMPS/POPS
PDT 49 67 41 70 / 20 60 0 0 ALW 49 65 43 69 / 20 80 0 0 PSC 49 73 41 74 / 20 70 0 0 YKM 49 71 39 74 / 20 10 0 0 HRI 49 71 41 73 / 20 70 0 0 ELN 48 65 40 72 / 30 10 0 0 RDM 41 63 32 70 / 10 20 0 0 LGD 44 60 36 67 / 20 80 0 0 GCD 42 60 35 69 / 10 70 0 0 DLS 50 67 41 74 / 20 30 0 0

PDT WATCHES/WARNINGS/ADVISORIES
OR...None.
WA...Wind Advisory from 2 PM to 8 PM PDT Tuesday for WAZ026.