Marine Weather and Tide Forecast for Snoqualmie, WA

SHORT TERM /TONIGHT THROUGH FRIDAY/
An upper ridge centered offshore continues to build into southern British Columbia today for another sunny day with temperatures just a little shy of seasonal normals. A surface ridge over the interior of British Columbia combined with low pressure over northern California continue to funnel breezy north winds through Puget Sound today.
An upper trough over central and southern California will shift eastward into the Great Basin on Wednesday allowing the ridge offshore to shift a little closer to Western Washington for more sunshine and a modest bump in temperatures. Surface gradients will be light by Wednesday morning which should allow for a little more morning fog coverage across south Puget Sound and the Southwest Interior.

The offshore ridge starts to flatten Wednesday night into Thursday in response to an upper trough entering the Gulf of Alaska. This will allow a weakening front to reach Western Washington Thursday night into Friday. The front will have minimal impact by the time it reaches the area with only a few hundredths of QPF expected across the lowlands east of the Olympic Peninsula.

LONG TERM /SATURDAY THROUGH TUESDAY/
While the initial front won't have much in the way of impact, it will, however, set the stage for a more active pattern this weekend. The offshore ridge is expected to give way as a 150+ knot jet stream carves out a broad upper trough over the northeast Pacific. This is expected to push a relatively strong frontal system into the area Saturday night into Sunday. Snow levels will be initially high in the warm sector of the system. Ensembles show a considerable spread in the QPF amounts with this system, but there's enough concern to warrant a day 5 Excessive Rainfall Outlook from the Weather Prediction Center for portions of the Olympic Peninsula. Snow levels are expected to fall back to the higher passes behind the front on Sunday.

Ensemble height anomalies lend a high degree of uncertainty to the forecast Monday and beyond. As such, a generic "chance of showers" forecast is a good compromise at this time.

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AVIATION
A transient upper level ridge will tilt northeast today with north flow weakening tonight into Wednesday. Surface high pressure is parked underneath this ridge in southern B
C
Clear skies/VFR continue this afternoon into tonight with north winds weakening through tonight from 8-12 kt this afternoon, down to under 5 kt (many will see light/variable or calm winds tonight). While gradients will be weaker tonight with calm winds, the risk for fog remains very low due to dry dewpoints still in the region with the lightly offshore pattern. If any fog mist forms, it is likely that it will be patchy in nature and the most likely areas to see any are terminals in the south Cascades, and the south interior. Otherwise, VFR is expected into tomorrow with light northwest winds 3-6 kt.

KSEA...VFR is expected through the TAF period. North-northeast winds 6-12 kt will become light tonight into Wednesday morning, becoming light out of the northwest 3-6 kt Wednesday afternoon.

HPR

MARINE
Northerly or weak offshore flow across the waters will weaken tonight as an area of low pressure to south of the area departs and an offshore surface ridge expands into the coastal waters. A weak front will arrive Thursday night into Friday with little to no impact. A much stronger frontal system will reach the waters Saturday night into Sunday with headlines expected for most of the waters. Coastal seas will build into the double digits this weekend and could exceed 15 feet by later Sunday. 27

SEW WATCHES/WARNINGS/ADVISORIES
WA...None.
PZ...None.