Marine Weather and Tide Forecast for Boardman, OR

DISCUSSION
Nighttime satellite imagery tonight shows cloudy conditions across the eastern mountains, with partly cloudy to mostly clear conditions elsewhere. While smoke continues to hang around the forecast area, surface observations tonight show that smoke has become "lighter", with most stations reporting visibility greater than 6 miles and few to scattered ceilings.

Sensible weather concerns through Thursday continue to revolve around a strengthening upper level ridge producing hot temperatures in and around the Columbia Basin; daily shortwave impulses riding up the ridge will tap into monsoonal moisture and increasing instability, producing isolated to scattered thunderstorms in the afternoons and evenings.

Through Thursday, the PacNW will remain under the influence of a gradually strengthening upper level ridge of high pressure while a deep southerly flow persists aloft. This will introduce increasingly hot temperatures across the lower elevations, with the brunt of the heating expected in the Columbia Basin/Gorge and adjacent foothills/valleys through Thursday afternoon.
Portions of the OR/WA Columbia Basin and the eastern Gorge are forecast to see high temperatures between 100 to 103 degrees this afternoon, with the Blue Mountain foothills, Yakima/Kittitas valleys, portions of north central Oregon, and portions of the John Day Basin reaching around 100 degrees (confidence 60-85%). While model guidance depicts the warming temperatures, regional smoke density continues to invite uncertainty in the effectiveness of daytime heating. Model guidance struggled with the impacts of smoke the past couple days, with yesterday's afternoon temperatures about 2 to 3 degrees below the forecast. With smoke expected to continue impacting portions of the region today and Thursday, there is moderate confidence (45-55%) that those areas(portions of the Blue Mountain Foothills, Columbia Basin, central OR, and eastern mountains) under denser smoke will see their afternoon temperatures about 2-3 degrees lower than what is forecast. Hot temperatures will continue in most areas Thursday, however increasing winds through the Cascade Gaps late afternoon will limit heating through the eastern Gorge and the Kittitas valley (confidence 65-80%). Between elevated afternoon and overnight temperatures, HeatRisk values across much of the lower elevations will be in the moderate to major categories, resulting in the Heat Advisories across the Columbia Basin/Gorge, Yakima Valley, and the northern Blue Mountain foothills.

Through Thursday, ensemble and deterministic guidance depicts a monsoonal moisture push riding the southerly flow into the intermountain PacNW, with daily PWATs around 0.75 to 1.25 inches. Weak shortwave impulses riding up the southerly flow will tap into the moisture and increasing instability to help initiate isolated to scattered thunderstorms. Today, the main thunderstorm activity will be focused across central OR and the mountainous terrain from the Cascade east slopes to the Ochoco mountains. In these areas, MUCAPE will be between 500-1000J/kg, low level lapse rates 8-10 C/km, and 0-6km shear between 20-40kts. These conditions will be more than enough for thunderstorms to develop in the afternoon and become organized as they propagate north. By Thursday, similar conditions will be present along the WA Cascades, Blue Mountains, and Wallowa county. Expect at least small hail, gusty outflow winds, frequent lightning, and a few storms to produce heavy downpours.

Late Thursday through the weekend, there is good agreement amongst ensemble cluster guidance that upper troughing will develop off the coast of the PacNW while upper level ridging pushes east and south. Southwest flow aloft will prevent monsoonal moisture from advecting into the region, resulting in drying conditions across the forecast area. The proximity of the upper trough late Thursday into Friday will also result in breezy west to northwest winds(15-25mph with gusts 25-35mph)
through the Cascade gaps and across the Columbia Basin.
Saturday, a shortwave will eject across northwest WA into BC, bringing breezy to windy conditions (gusts up to 50mph) through the Cascade gaps, with breezy conditions across the remainder of the forecast area. Friday, there is moderate confidence (55-65%) that peak winds will overlap with critically low RHs in portions of the Columbia Basin and Cascade Gaps. On Saturday, there is moderate confidence (40-55%) winds and low RHs will overlap in areas of the Columbia Basin and eastern mountains.
Otherwise, the shortwave passage will also result in light rain showers developing along the WA Cascade crest through Sunday morning (confidence 50-65%). Sunday through Tuesday, the forecast area will remain under a mild, dry southwest flow aloft with diurnally driven breezy winds, near to below normal temperatures, and dry conditions (confidence 45-60%). Lawhorn/82

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
Mix of conditions across the region through the period. Smoke will continue to bring MVFR or lower vsby/CIG impacts to sites PDT/ALW/RDM/BDN this morning, with conditions expected to improve to VFR by the afternoon. At least rain showers are expected to impact sites RDM/BDN this afternoon and evening, with a Prob30 chance that the sites are impacted by thunderstorms with variable gusty outflow winds between 22-03Z. There is also a Prob30 chance of showers at site DLS between 00Z-04Z. Winds will increase at site DLS around 04Z to 12-20kts with gusts up to 30kts possible through the end of the period. Winds will otherwise remain light at all other sites through the period. Lawhorn/82



FIRE WEATHER
Conditions will remain hot and dry through Thursday, with hottest conditions in the Columbia Basin and adjacent foothills/valleys. However, areas under heavy smoke will see less heating than anticipated. Monsoonal moisture and increasing instability will bring isolated to scattered thunderstorm chances through Thursday. Today, chances (20-50%)
will be focused across central OR, OR Cascades, and Ochocos.
Chances (15-35%) Thursday will be focused along the WA Cascade crest, Blue Mountains, and Wallowa county. Thunderstorms will be capable of frequent lightning, gusty outflow winds, small hail, and brief heavy downpours. Winds will increase through the Cascade Gaps and Columbia Basin Friday, and are expected to overlap with near to critically dry conditions, resulting in elevated fire weather conditions. A weak system passage Saturday may result in breezy conditions area wide, with peak winds overlapping with critically low RHs in the eastern mountains and portions of the Columbia Basin in the afternoon. Lawhorn/82

Preliminary Point Temps/PoPs
PDT 99 67 96 63 / 0 0 10 0 ALW 102 72 99 69 / 0 0 10 10 PSC 103 70 101 65 / 0 0 0 0 YKM 102 72 100 64 / 0 10 10 0 HRI 103 71 98 66 / 0 0 0 0 ELN 100 69 95 61 / 0 10 10 0 RDM 95 59 93 55 / 40 40 0 0 LGD 99 67 100 63 / 0 0 30 10 GCD 97 63 99 59 / 10 10 10 0 DLS 104 71 91 65 / 0 10 10 0

PDT WATCHES/WARNINGS/ADVISORIES
WA...Heat Advisory until 9 PM PDT Thursday for WAZ024-027>029.
Air Quality Alert until 9 AM PDT this morning for WAZ028>030.
OR...Heat Advisory until 9 PM PDT Thursday for ORZ041-044-507.
Air Quality Alert until 4 PM PDT this afternoon for ORZ044-049- 050-502-503-505>509-511.
Red Flag Warning from 11 AM this morning to 11 PM PDT this evening for ORZ698-700-705.