Marine Weather and Tide Forecast for Boardman, OR

DISCUSSION
Today through Thursday: A strong upper low with a leading cold front dropping out of the Gulf of Alaska will move across the PacNW starting today, bringing with it widespread rain and mountain snow chances (confidence 80-85%). The best precipitation chances in the lower elevations will be associated with the cold front passage late tonight through Wednesday afternoon, with chances tapering off late Wednesday through Thursday. The upper low and cold front will bring a much colder airmass to the region, resulting in snow levels steadily dropping to below pass levels by tonight, and between 1.5kft to 2kft by Wednesday evening. While the bulk of precip will fall before Wednesday evening in the lower elevations, portions of central and north central OR will see light rain transition to light snow. Otherwise, moderate to locally heavy snow showers will develop across the Cascade crest and the northern Blues this evening through Wednesday evening, with snow tapering off through Wednesday night and Thursday. Multiple winter weather headlines are in effect today through Wednesday night in anticipation of impacts from the heavy mountain snow. There remains high confidence (80-85%) in snow accumulations between 6-12 inches for the OR Cascade east slopes above 4000 feet, 4-8 inches for the upper east slopes of the WA Cascade east slopes, and 5-10 inches for the Northern Blues above 4500 feet. The heaviest snow accumulations are expected later tonight as the cold front slides through the region, with upslope snow showers persisting through the remainder of Wednesday.

Breezy winds will continue to impact the region through the midweek as the cold front passage and continued cold air advection into the forecast area result in tightened pressure gradients. Confidence is moderate-high (55-85%) that westerly winds will remain between 15-30mph and gusts 25-45mph through the midweek. That said, wind-prone areas in the Columbia Basin and Blue mountain foothills will see a 65-85% chance of gusts exceeding 45 mph each day through Thursday. Otherwise, clearing skies, dry surface conditions, and cold air advection into the region will result in near to below freezing morning temperatures Thursday and Friday. Of particular concern are the Kittitas and Yakima valleys, where there is 65-85% chance of morning lows below freezing Thursday and Friday.

Friday through Monday: Ensemble guidance is in good agreement of upper level ridging sliding across the PacNW with dry conditions and light winds by Friday (confidence 60-75%). The forecast area will remain under the influence of the ridge through Saturday afternoon, but ensemble members disagree on the evolution of the synoptic pattern late Saturday into Monday.
That said, there is good agreement in some form of upper low bringing another round of precipitation chances to the region Sunday into early next week. Lawhorn/82

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
VFR conditions to prevail through the period. An upper level system will bring rain impacts to sites beginning late this afternoon, with shower chances developing at sites PDT/ALW/PSC between 23Z and 6Z.
Light rain will develop at site DLS after 6Z and persist into the end of the period. Winds will increase to 12-20kts with gusts 20-30kts at all sites today, with winds becoming light at sites DLS/RDM/YKM around 2-3Z. Otherwise, winds will remain elevated at all other sites through the period. Lawhorn/82

Preliminary Point Temps/PoPs
PDT 58 41 52 31 / 10 60 90 40 ALW 58 42 52 34 / 20 80 100 60 PSC 61 44 58 34 / 20 40 70 20 YKM 58 39 55 30 / 20 60 30 10 HRI 60 42 57 33 / 10 40 80 20 ELN 51 32 48 29 / 40 70 30 10 RDM 56 35 49 23 / 10 50 90 30 LGD 56 39 49 29 / 10 90 100 70 GCD 58 38 48 26 / 10 70 100 70 DLS 58 41 54 35 / 40 80 70 20

PDT WATCHES/WARNINGS/ADVISORIES
WA...Winter Weather Advisory from 5 PM this afternoon to 11 PM PDT Wednesday for WAZ030.
Winter Weather Advisory from 11 AM this morning to 11 PM PDT Wednesday for WAZ522.
OR...Winter Weather Advisory from 5 PM this afternoon to 11 PM PDT Wednesday for ORZ502.
Winter Storm Warning from 5 PM this afternoon to 5 AM PDT Thursday for ORZ509.