textproduct: Seattle/Tacoma

SYNOPSIS

A broad upper level trough will continue to produce unsettled and cool conditions across Western Washington into midweek along with chances for mainly mountain showers. Drier conditions and a modest warming trend are expected for the upcoming holiday weekend with a weak ridge of high pressure aloft.

SHORT TERM /TODAY THROUGH WEDNESDAY/

No significant updates to the forecast this morning. Stratus will prevail through much of the day, with clouds trying to break late this afternoon. This will keep temps moderated, currently in the mid 50s, reaching the mid to upper 60s this afternoon. 62

Western Washington remains under the influence of broad upper troughing aloft and low level onshore flow. At the risk of sounding like a broken record, the forecast into midweek will largely mimic what we saw yesterday. Night and morning low clouds will stubbornly give way to a few peeks of late day sun over the interior lowlands and temperatures will be held several degrees below seasonal averages. A series of weak disturbances moving through the trough will occasionally kick off a shower over the higher terrain or squeeze out some coastal drizzle, but otherwise mainly dry conditions will prevail.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

The long term forecast period begins with much the same trend of cool unsettled conditions. A few of the operational model runs attempt to bring a weakening frontal system into the area on Thursday, but it may well encounter a building ridge offshore and result in little if any precipitation away from the coast and Olympic Peninsula.

As we move toward the upcoming holiday weekend, ensembles are continuing the trend of previous runs which have upper troughing retreating into the northern Gulf of Alaska and at least some upper ridging rebuilding into the Pacific Northwest. There's still a decent spread in solutions with regard to the strength of the ridging, but the overall ensemble averages suggest a return to temperatures near, if not a little above, seasonal norms for early July along with dry conditions.

27

AVIATION

Broad upper troughing over the interior West will continue to maintain northwesterly flow aloft over Western Washington. MVFR to IFR cigs prevail across western Washington this morning, but is expected to slowly lift throughout the morning to low-end VFR by the afternoon for interior terminals. Clouds will likely try to break but ceilings are not expected to fully scatter. Ceilings will likely deteriorate back to low MVFR or localized IFR once again tonight and through much of Tuesday morning.

KSEA...MVFR with occasional periods of IFR this morning. Expecting slow improvement through the morning, with low-end VFR after around 21Z. Ceilings may become broken but not expecting full scattering. Ceilings will fall back to MVFR late tonight and continue through Tuesday morning. Surface winds south to southwesterly 7 to 10 knots rising to 9 to 12 knots later this evening.

27/62

MARINE

A broad surface ridge centered well offshore and lower pressure across the interior will remain the dominant weather pattern into midweek. This will maintain onshore flow with gusty northwesterlies and steep seas for the coastal waters. Diurnally driven westerly pushes will occur in the Strait of Juan de Fuca as well. The offshore ridge is expected to weaken during the later half of the week as a broad surface low approaches the central British Columbia coast. This will weaken onshore flow allowing winds over the coastal waters to ease and seas subside.

27

FIRE WEATHER

Little in the way of fire weather concerns remain in the picture into the week ahead with upper troughing maintaining cool conditions, high RH, and periodic chances for shower activity. A trend toward more seasonable temperatures is indicated toward late week, but a significant warm and dry spell is not expected in the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 5 PM this afternoon to 2 AM PDT Tuesday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 5 PM PDT Tuesday 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.