textproduct: Seattle/Tacoma

SYNOPSIS

An upper level low will meander across the region this week with recurring spells of showers. Transient ridging will bring above average temperatures for both Wednesday and Thursday before a subsequent cool down into the weekend. Models are hinting at additional ridging early next week.

SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/

An upper-low is positioned over much of the US West Coast this evening. As a result, showers have been observed so far today across W WA. However, the aforementioned low will drift southward tonight as an upper-ridge off the NE PAC noses into the area. Conditions will trend drier tonight but low-level moisture will remain. Low clouds and fog are forecast - primarily around South Sound and Chehalis River valley but also areas of the interior. Overnight lows are expected in the 40s to near 50 F.

As mentioned, upper-ridging will be the main player on Wednesday and Thursday. Temperatures are forecast to warm above average with highs in the lower 70s to near 80 F on Wednesday and upper 70s to lower 80s on Thursday. Wrap-around moisture from the west coast upper-low looks to stream into the region Thursday afternoon. Here we could see elevated thunderstorms across the Cascades as the SPC has a general risk outlook for this day. Overnight lows generally in the 40s to lower 50s.

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LONG TERM /FRIDAY THROUGH TUESDAY/

Models in good agreement with a series of shortwaves moving through the area over the weekend. Not much in the way of moisture with the troughs but the low level flow will remain onshore. This will keep clouds in the forecast with highs in the lower to mid 60s Saturday and mid to upper 60s Sunday. Upper level ridge building into the area Monday as daytime temperatures warm into the 70s to lower 80s.

Lows near 50 Friday morning. A little cooler Saturday, Sunday and Monday mornings with the colder locations getting down to near 40. Mid to upper 40s for the remainder of the area.

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AVIATION

Showers coming to an end over the local area with light flow aloft as the upper low drops south and east of the area. This is bringing some clearing across western Washington with just a few pockets of ceilings remaining. Expect clouds to redevelop with MVFR conditions along the coast and a few patches of MVFR ceilings in the interior. Improvement through the morning hours Wednesday with widespread VFR conditions area-wide Wednesday afternoon.

KSEA...VFR conditions this evening with broken to scattered mid level deck around 4500 ft. North winds around 7 kt this evening, easing overnight. Could see a few patchy MVFR ceilings around the terminal area toward 12z, but expect VFR ceilings to likely prevail. VFR with scattering clouds through the day Wednesday as north surface winds increase to 10 kt. Cullen

MARINE

High pressure is rebuilding over the northeastern Pacific this evening. A Small Craft Advisory remains in effect for the coastal waters due to seas and winds. With the transition back to northwesterly winds, steep seas will also return to the coastal waters late Tuesday into Wednesday as the predominant wave group's period becomes 10 seconds. The arrival of a 7-10 ft swell with a very long period of 16-19 seconds on Thursday will bring confused seas as significant wave heights builds back to 11-13 ft. Seas then again subside slowly Friday into the weekend. Expect a stronger west push Thursday and Friday nights through the Strait of Juan de Fuca with a 50-60% chance of gales in the central and portions of the eastern Strait. Cullen

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 until 5 AM PDT Wednesday 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-Grays Harbor Bar.

Small Craft Advisory until 5 PM PDT Wednesday 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.