textproduct: Seattle/Tacoma

SYNOPSIS

Cool upper level low moving over the area this morning will slowly move southeast into Eastern Oregon by Sunday morning. Weak convergence over the Puget Sound ending this morning. Dry northeasterly flow aloft tonight through Monday with high pressure nosing into British Columbia. Ridge moves over Western Washington Tuesday and weakens with a weather system moving by to the north Tuesday night into Wednesday. Upper level ridge building over Western Washington from the south Wednesday night through Friday. Low level flow turning offshore producing a couple of warm days the latter part of next week.

SHORT TERM /TODAY THROUGH MONDAY/

The latest forecast remains on track this morning with minor updates to the Aviation and Marine sections below. Cool upper level low moving over the area today. Weak convergence producing the shower activity will dissipate this morning. Low not strong enough to create any shower activity this afternoon. Main result of the low overhead will be the cool daytime temperatures with highs in the mid and upper 50s. Seattle high Friday was 58 degrees, coolest high since May 15th ( 51 degrees ). Going for 57 degrees in Seattle today.

Upper level ridge nosing into British Columbia combining with the upper level low drifting southeast producing dry northeasterly flow aloft tonight and Sunday. Skies clearing later this afternoon into tonight. With the clearing skies lows dropping into the mid 30s to mid 40s. The frost advisory from midnight to 8 am Sunday for portions of King, Pierce, Lewis and Thurston counties remains in effect. Highs warming back to near normal, upper 50s to mid 60s.

Upper level low sinking south Sunday night and Monday. Upper level ridge remaining over Southern British Columbia with a continuation of the dry northeasterly flow aloft. Low temperatures even cooler Sunday night/Monday morning with most places in the 30s. The last time Olympia had a low of freezing or below was May 17th ( 32 degrees ). Another frost advisory will be issued covering a larger area, most areas south of Seattle plus the Hood Canal and North Coast for Monday morning. Highs Monday again in the upper 50s to mid 60s. Felton

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

Upper level ridge axis moving south over Western Washington Monday night into Tuesday. Weak atmospheric river settling up Tuesday night into Wednesday aimed at Vancouver Island. A few of the ensemble solutions have Western Washington on the southern edge of this feature. Enough solutions to have a chance of rain in the forecast Tuesday night and Wednesday. Lows in the mid 30s to lower 40s Tuesday and in the 40s Wednesday. Highs both days in the upper 50s to mid 60s.

Upper level ridge building in from the south Wednesday night into Thursday. 500 mb heights rising to the lower to mid 580 dms. Low level flow turning offshore as a front stalls well off the coast. Right now it looks like a couple of warm days for Western Washington with the warmer locations getting into the lower 70s. Nowhere near records but still at least 5 degrees above normal. Lows in the 40s.

Felton

AVIATION

Northwest flow aloft will become northeasterly late today as an upper level low sinks southward over the Pacific Northwest. A mix of MVFR and VFR ceilings in scattered showers this morning will become VFR most areas this afternoon (after 18Z-20Z) with shower activity diminishing as the upper low shifts southeastward away from Western Washington. Areas of LIFR fog are likely to form in outlying valleys and across the Southwest Interior on Sunday morning. Winds will get breezy for central Puget Sound terminals this afternoon with gusts to 15 kt possible.

KSEA...MVFR ceilings at the terminal this morning. Improvement expected after 19Z-20Z to VFR. Southeasterly winds this morning will transition northerly after 18Z at 6-10 kt. There is a 50-60% chance for gusts up to 15 kt this afternoon.

27/29

MARINE

The small craft for the interior coastal waters has been extended this morning through 11 AM, as observations have shown seas have receding slower than expected and continue to hover around 10 feet.

A weak surface low over the coastal waters this morning will shift southward today. High pressure building over the interior of British Columbia will lead to increasing northerly or offshore flow tonight into Sunday. Winds will be briefly enhanced in the Northern Inland Waters near the San Juans and off the coast in the central and southern coastal waters zones, with potential for wind gusts to approach Small Craft criteria tonight into early Sunday morning.

Winds ease early next week as high pressure over interior British Columbia weakens and broad surface ridging remains centered well offshore. Another frontal system will reach the waters Tuesday night into Wednesday.

Coastal seas of 10 to 12 feet will subside later today and are then expected to remain under 10 feet well into the upcoming week.

27/29

SEW WATCHES/WARNINGS/ADVISORIES

WA...Frost Advisory from midnight tonight to 8 AM PDT Sunday for Foothills and Valleys of Pierce and Southern King Counties-Foothills and Valleys of Thurston and Lewis Counties-Middle Chehalis River Valley.

Frost Advisory from midnight Sunday night to 8 AM PDT Monday for Eastern Kitsap County-Foothills and Valleys of Pierce and Southern King Counties-Foothills and Valleys of Thurston and Lewis Counties-Foothills of the Western and Southern Olympic Peninsula-Lake Crescent Area Including US 101-Lowlands of Lewis and Southern Thurston Counties- Lowlands of Pierce and Southern King Counties-Middle Chehalis River Valley-Northern Hood Canal-Northern Washington Coast-Olympia and Southern Puget Sound- Southern Hood Canal-Willapa and Black Hills.

PZ...Small Craft Advisory until 11 AM PDT this morning for Coastal Waters From Cape Flattery To James Island Out 10 Nm- Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.

Small Craft Advisory until 2 PM PDT this afternoon 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.