textproduct: Seattle/Tacoma

SYNOPSIS

Onshore marine air keep most of western Washington in the clouds today into Tuesday with pockets of drizzle and a shower or two at times. A ridge will push through Wednesday into Thursday with more sunshine, with increased cloud coverage finishing the week as a dry trough passes through. Stronger high pressure combined with a thermal trough early next week may produce the first 80 degree weather of the year for western Washington.

SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/

Sunshine has vanished for most in western WA today as stronger marine push continues. Satellite shows a meso low feature just off the tip of Neah Bay rotating clouds across the coast, rotating the clouds inland on the south side of the Olympics, and pushing inland through the interior. There is evidence of a break up of some of the clouds up in Whatcom County early this afternoon, and this will likely spread southwards into the interior this evening to at least give a few glimpses of the sun before dusk. Clouds will fill in again tonight/Tuesday with another overcast day expected. Couple pockets of drizzle/showers cannot be ruled out either with the marine air. Temperatures with the cloud coverage only climb into the upper 50s/low 60s, with lows in the mid/upper 40s. Winds remain out of the southwest around 5-10 mph.

A ridge moves over the region Wednesday, with increased northerly flow aloft expected to disrupt the marine pushes. Sunny skies are expected for much of the west side of the state as the ridge passes overhead. Temperatures on Wednesday will be a few degrees warmer with highs in the mid/upper 60s, and lows Wednesday night in the low 40s/upper 40s. Couple pockets of minor HeatRisk cover the Seattle metro into the south interior.

LONG TERM /THURSDAY THROUGH MONDAY/

The ridge from Wednesday will continue to move eastward Thursday. The day will start out sunny with clouds beginning to return as a trough/cold front pass through the region dry. Cloud coverage will remain into Friday/Saturday with onshore flow behind the cold front. Temperatures dip from the upper 60s/low 70s Thursday into the mid/upper 60s Friday. Most ensembles are showing a large bubble of high pressure forming just offshore the Pacific Coast, with a large ridge extending into far northern B.C. Canada. Depending on how strong a potential thermal trough picks up along the coast underneath the ridge, this could be the first chance western WA has of seeing high temperates at or above 80 this season (looking at Sunday and Monday). The lows during this time appear to cool still in the upper 40s to low 50s, but will have to watch for pockets of moderate HeatRisk with this warm and dry pattern coming up.

HPR

AVIATION

MVFR cigs have been slow to lift this afternoon. However, still expecting VFR cigs this afternoon/evening, with the exception of terminals along the coast, where cigs will remain MVFR. Another push of onshore flow will bring another round of widespread marine stratus to the interior terminals, with MVFR cigs expected after 08-12z. There is a 20-35% chance of IFR cigs for the Kitsap Peninsula and north Puget Sound. Improvement to VFR expected Tuesday afternoon for all terminals after 21-23z Tuesday. Breezy S/SW winds today 8-12 kt with gusts to 20 kt, decreasing early Tuesday morning to 4-8 kt.

KSEA...Stratus ceilings bouncing between MVFR and VFR this afternoon. However, the general trend for this afternoon is expected to be VFR. MVFR cigs return overnight around 10z, with another push of marine stratus. VFR cigs likely to return after 22z. Breezy S/SW will continue at the terminal today with sustained speeds around 8- 12 kt and gusting to 20 kt. Winds will gradually subside early Tuesday morning to 6-8 kt.

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MARINE

Broad high pressure over area waters will prevail into next week. Onshore flow will increase this evening across area waters this evening into Tuesday. As a result, expect a push of westerlies through the Strait of Juan de Fuca. The strongest winds will be along the central portion of the Strait, but have held off on issuing any advisories as current probabilities of winds exceeding 21 kt are around 35-55%. However, an occasional gust to 21 kt cannot be ruled out. Steep seas are expected over the outer coastal waters with combined seas building to around 7-9 ft with a dominant period of 8-9 seconds. Latest guidance is suggesting that steep seas may continue into late in the week, for which additional advisories may be needed. A weak cold front will move across area waters on Thursday and high pressure will weaken slightly. Seas will build to 8-12 ft late Thursday, before decreasing to 6-8 ft on Friday. High pressure will rebuild right behind the front.

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HYDROLOGY

No river flooding is expected in the next seven days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 5 PM this afternoon to 9 AM PDT Tuesday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm.