Marine Weather and Tide Forecast for Seattle, WA

SHORT TERM /TODAY THROUGH WEDNESDAY/
Upper-troughing currently over the Great Basin while an upper- level ridge is just offshore the PNW. High clouds are currently streaming in under northwest flow aloft. Areas of fog/low stratus are still likely to develop this morning but coverage will be at a minimum. Any fog that should form will give way to sunshine today as the aforementioned ridge centers overhead.
High temperatures are forecast in the 60s across the interior with 50s along the coast. Increasing onshore flow will lead to breezy winds through the Strait of Juan de Fuca this evening with gusts up to 30 mph on Whidbey Island before gradually decreasing later tonight. HRRR suggests a 35% chance of gusts exceeding 35 mph. Overnight lows will fall into the 40s.

Upper-ridging is likely to maintain through midweek as conditions remain rather benign. Weak disturbances will attempt to traverse along the periphery of the ridge - maintaining slight (15% or less) PoPs but mostly for the mountains.
Temperatures are to remain near-seasonal throughout this period with highs in the 60s to near lower 70s and lows in the 40s.



LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
The upper level ridge offshore will begin to flatten on Thursday as a low pressure system slowly strengthens and lowers from the Gulf of Alaska. Conditions are favored to remain dry into the first half of the weekend as zonal flow sets up aloft, with continued mild temperatures. Ensembles are honing in on a potential pattern change by the end of next weekend, with increasing chances for widespread rainfall arriving Sunday evening. However, the details remain uncertain at this time.

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AVIATION
North/northwesterly winds will persist aloft as an upper level ridge remains nudged over the region. Onshore flow will continue in the low levels, allowing for another round of stratus to push inland this morning, mainly for areas along the coast, the Southwest Interior, and the south Sound. A few isolated spots of patchy fog may also develop across the Chehalis Valley and Kitsap Peninsula early this morning, though high clouds streaming in overhead should help hinder any widespread development. Conditions at the area terminals remain VFR, though could see terminals briefly dip down to MVFR between 12-15Z (most likely for KHQM, KPWT, and KOLM). Expect cigs at the remainder of the terminals to remain VFR through the day.

Winds remain light southerly at 6 kt or less across the majority of the interior terminals this morning, outside of KPAE, where winds continue out of the north. Winds along the coast are light northwesterly and KCLM remains westerly between 8-12 kt under increased onshore flow. Winds will increase to 7-10 kt this afternoon and look to switch to the north across the interior between 00-03Z tonight. A weak, splitting frontal system will move into the area tonight into Tuesday, with the main impact being more widespread stratus by Tuesday morning.

KSEA...Ceilings look to remain VFR through the day, with a few scattered clouds possible at the terminal between 2000-3000 ft early this morning. The latest probability of ceilings dipping to MVFR is 15 percent this morning. A much greater probability (40-45 percent) exists of ceilings dropping to MVFR by Tuesday morning. Winds are southerly and will increase to 7-10 kt this afternoon, before switching to the north between 00-03Z.

14

MARINE
High pressure will remain situated over the northeastern Pacific through much week, bringing a prolonged period of north/northwesterly winds to the coastal waters. A weak, splitting frontal system will move into the waters tonight into Tuesday and will bring an increase of onshore flow along the central and eastern Strait of Juan de Fuca, with another round of small craft westerlies expected this afternoon and evening.

High pressure will build back into the coastal waters in the wake of the front. Onshore flow will persist throughout much of the week and will result in daily pushes of westerly winds along the Strait. The next weak frontal system looks to move into the area waters Thursday into Friday, followed by another late next weekend.

Seas will generally hover between 6-8 ft through the first half of the week, before increasing towards 8-10 ft mid to late week.
The latest GEFS probabilistic guidance is highlighting roughly a 20-40 percent chance of seas exceeding 9 ft by next weekend.

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HYDROLOGY
The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated during this time as needed.

SEW WATCHES/WARNINGS/ADVISORIES
WA...None.
PZ...Small Craft Advisory until 5 AM PDT early this morning for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 2 PM this afternoon to 5 AM PDT Tuesday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca.