textproduct: Seattle/Tacoma

SYNOPSIS

High pressure aloft will rebuild across the region into Tuesday for warm and drier conditions. An area of low pressure may bring a threat of showers and thunderstorms around midweek before high pressure regains control toward the weekend for a return of dry conditions and well above normal temperatures.

SHORT TERM /TODAY THROUGH WEDNESDAY/

Mostly clear conditions exist across Western Washington this morning. High pressure aloft will continue to build over the region today as an area of low pressure digs southward offshore. The warming trend continues into Tuesday as the ridge continues to strengthen over the area with the offshore trough becoming cut- off. High temperatures will get into the 80s for interior areas...especially Seattle southward...with portions of the Seattle-Tacoma area getting into likely Moderate HeatRisk. Warm temperatures for interior areas continue into Wednesday with the ridge in place for continued likely Moderate HeatRisk for a large swath of the Seattle-Tacoma corridor.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

Uncertainty in the forecast becomes a significant factor by Thursday as models continue to struggle with the path of the cut-off low offshore. A significant portion of the ensembles, especially the suite of ECMWF solutions, suggest a continued threat of showers and/or thunderstorms on Thursday coupled with a brief cool down. Negatively tilted lows such as this often have a way of initiating elevated instability with no deference to the time of day. This will continue to pose a fire weather concern and need to be monitored closely.

Once this system exits the area, models remain pretty locked in with strong upper ridging for an extended period of well above normal temperatures and dry conditions for the weekend and beyond.

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AVIATION

Southwesterly flow aloft will persist into Tuesday. Surface winds generally light and variable although some terminals reporting northerly winds 4-8 kts. By this afternoon, most terminals should be reporting similar direction and speed...with some variances to the northeast or northwest.

Some high clouds in place over W WA this early morning with vast swaths of clear skies. Otherwise, VFR conditions are expected for remaining terminals throughout the forecast period.

KSEA...VFR throughout the period. N/E winds 5-10 kts early this morning, and likely to remain that way into the afternoon before a slight shift to the NW by 22Z. Returning northerly with speeds easing slightly to 4-8 kts this evening and overnight with VFR continuing.

18/Mazurkiewicz

MARINE

Surface high pressure over area waters throughout the next few days. Diurnal westerly winds through the Strait of Juan de Fuca will be the main theme. Speeds for the most part look to remain below SCA criteria, with tonight being the exception where speeds look to run 15-25 kts. As such, a Small Craft Advisory has been issued starting late this afternoon and running into tonight. Coastal waters may also see wind gusts approach 20 kt towards the end of the week on Thursday and Friday with another low system tracking through the waters.

Seas for the majority of the forecast will remain at 4-6 ft, with the system Thursday/Friday increasing seas to 7-8 ft with periods around 6-8 seconds.

41/18

FIRE WEATHER

Warming temperatures this week will increase the fire weather risks going into the weekend. A potential cut- off low pressure system arriving around midweek remains a concern for convection and associated risks of lightning strikes with fuels now running quite dry.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 5 PM this afternoon to 1 AM PDT Tuesday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca.