textproduct: Seattle/Tacoma

SYNOPSIS

Another cool and cloudy start to the day is expected, breaking out in the afternoon for more sunshine. A low pressure system brings rain, breezy winds and chances for thunderstorms to the region on Monday. Showery weather continues on Tuesday, with a return to high pressure likely later in the week.

SHORT TERM /TODAY THROUGH TUESDAY/

Another round of stratus clouds are expected this morning, retreating back toward the coast in the afternoon for sunnier skies. Highs are likely to be in the mid to upper 60s, possibly 70 in locations that clear the stratus first. Today will be the last dry day of the long weekend, as a low pressure system brings rain, breezy winds and slight chances for thunderstorms to the region on Monday (Memorial Day).

Rain is likely to arrive on the coast late tonight, spreading inland throughout the day on Monday. QPF looks to be around a tenth to quarter inch for the lowlands, and up to an inch on the windward slopes of the Olympics. Breezy south to southwesterly winds will pick up late Monday morning, and will be strongest along the immediate Pacific coast, Admiralty Inlet, eastern Strait of Juan de Fuca and in the northern inland waters from Skagit county north. These areas may see gusts of 35 to 40 mph. Unsecured outdoor items like tents may be at risk during these winds. Additionally, while SPC has western Washington highlighted for general thunderstorm risk on Monday, outdoor events could still be impacted by typical thunderstorm hazards such as heavy rain and lightning. Chances are slight, around 10 to 20%, but remember to head indoors when thunder roars. Temperatures on Monday will be a lot cooler, down into the upper 50s and low 60s.

Showery and unsettled weather continues into Tuesday as the trailing front moves through the region. Isolated thunderstorm chances remain in the forecast.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/

The low pressure system responsible for Monday and Tuesday's weather will continue to dig south, leaving the PNW in split flow to gentle ridging into the mid and late week. As such, temperatures begin to warm from Wednesday onward, reaching highs back into the mid 70s by Thursday. Ensembles and deterministic guidance are hinting at broader troughing over the NE Pacific late in the week for potential for more unsettled weather.

With the broader NE Pacific troughing, long period swell arriving Thursday poses a bigger threat for extended wave runup on coastal beaches.

21

AVIATION

West-southwest flow aloft through today with weak ridging over the Pacific Northwest. Weak onshore flow continues in the low levels. Low-end VFR stratus deck continues early this morning across central Puget Sound. Areas of MVFR stratus also exist across portions of the Olympic Peninsula with increasing high clouds. This general trend will continue through the morning, with high end MVFR at times from KPAE towards KOLM. Otherwise, VFR cigs expected this afternoon with SCT/BKN high clouds. Clouds will then increase further tonight ahead of a frontal system on Monday. Light winds this morning will become predominantly S/SW this afternoon.

KSEA...Low-end VFR to high end MVFR cigs expected through 16-18z this morning, with cigs mainly between 025 to 050. VFR conditions this afternoon into tonight with high clouds at times. Light SW winds through this afternoon mainly ranging 3 to 7 kts. JD

MARINE

High pressure will weaken through today with lighter winds into this evening across area waters. A low pressure system will move through the waters on Monday bringing increasing south to southwest winds. Winds will peak late tonight into Monday morning for the Coastal Waters and during the day Monday for interior waters. A Gale Watch has been issued for the Coastal Waters, as well as the eastern Strait of Juan de Fuca and northern inland waters. Probabilities for wind gusts exceeding 35 kts range 50 to 80 percent for these areas, thus giving enough confidence for a Gale Watch at this time. Small Craft Advisory winds are also expected for most other waters on Monday. Winds will slowly ease late Monday into Monday night. High pressure will then build back Tuesday into Wednesday bringing the return of Small Craft Advisory northerly wind gusts and steep seas to the outer coastal waters.

Seas will range 6 to 8 feet through this evening before building to 12 to 16 feet by late Monday. Waves will peak around 13 to 16 feet into Tuesday morning before slowly subsiding to near 10 feet by Wednesday. A long period swell arrives Wednesday night into Thursday. This, combined with continued northwest surface winds, results in seas building again to 10 to 13 feet. JD

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 from 2 AM to 5 PM PDT Monday for West Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Warning 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.

Gale Watch from late tonight through Monday afternoon for East Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters Including The San Juan Islands.

Small Craft Advisory until 5 AM PDT early this morning for Admiralty Inlet.

Small Craft Advisory from 5 AM to 5 PM PDT Monday for Admiralty Inlet.

Gale Watch from this evening through Monday morning for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.