textproduct: Seattle/Tacoma

UPDATE

Low stratus remains deeply entrenched over much of the lowlands this morning, with pockets of fog underneath gradually improving. Sun breaks are expected to develop by the mid to late afternoon, with cloudy skies expected to remain with better visibilities at the surface. As high pressure builds inland, light winds and residual moisture at the surface will likely result in widespread fog and low stratus early Monday morning with areas of greatly reduced visibility. Confidence not high enough this morning to issue a Dense Fog Advisory for Monday morning, but conditions will continue to be monitored. No other updates to the forecast this morning outside of the Aviation and Marine sections below.

SYNOPSIS

Dry conditions will continue across western Washington through Monday as an upper level ridge moves over the Pacific Northwest. The first half of the week will largely remain dry across the area, with chances of precipitation increasing the second half of the week as a series of systems approaches the Pacific Northwest. A brief break in the unsettled pattern is possible Friday night into Saturday as another ridge moves over the region.

SHORT TERM /TODAY THROUGH TUESDAY/

An upper level ridge will move into the region today and push inland on Monday, maintaining dry conditions across western Washington for the start of the week. Overnight lows will remain cool, mainly dipping down into the 30s, and will bring areas of additional frost development during the early morning hours. Ample moisture in the low levels will also promote another round of fog development across the western Washington on Monday morning. Afternoon highs will be seasonable, mainly in the low to mid 50s both days.

A splitting system approaching the region Monday night into Tuesday may bring some light precipitation to portions of the coast and the Olympic Peninsula. The majority of western Washington will remain dry, however, with temperatures warming a few degrees. Morning lows will be in the mid 30s to mid 40s across the area, with afternoon highs expected to be in the mid 50s to low 60s.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/

Chances for precipitation will increase the second half of the week as a series of systems looks to approach the Pacific Northwest. At this time, a weak system looks to move across the area on Wednesday, followed by a stronger system on Friday. The stronger system on Friday will likely bring gusty winds and more widespread lowland rain and mountain snow to the area. Discrepancy still exists with the pattern heading into next weekend, but ensemble clusters hint at a brief break in the parade of systems Friday night into early Saturday as a ridge of high pressure temporarily moves back over the region. The ridge looks to push inland rather quickly however, which would open the door for additional systems to move into the area by Saturday evening.

Temperatures will be near to just slightly above normal through the period, with morning lows expected to be in the upper 30s to upper 40s and afternoon highs expected to be in the mid to upper 50s.

14

AVIATION

MVFR to LIFR conditions this morning associated with low stratus or fog. Improvement to VFR likely after 20-23Z. Model guidance suggests another round of stratus and fog likely by Monday morning for Puget Sound terminals and along the coast. Light northerly surface winds today across the interior terminals at 5 kt or less. Along the coast southeasterly winds will transition northerly this afternoon at 5-7 kt.

KSEA...MVFR cigs this morning with thick stratus over the terminal. Now expecting the stratus to scatter out by 21-23Z. Guidance hints at another chance for low cigs Monday morning. As of now, thinking IFR low stratus may impact the terminal rather than fog. While confidence is low that fog will impact the terminal, fog may form near the vicinity of the terminal. Latest guidance suggests improvement to VFR Monday afternoon after 21Z. Light NW winds today at 5 kt or less, becoming NE this evening.

29

MARINE

High pressure rebuilds over the coastal waters today with dry conditions finishing the weekend over the waters. Couple patches of fog may affect portions of the Puget Sound waters this morning. A weak system will brush the coastal waters Monday into Tuesday with the chance of showers. While winds will pick up in the outer coastal waters (with winds gusting up to 20 kt), the main concern for the first part of the week will be seas increasing to 8-11 ft going into tonight/Monday. A small craft advisory was issued to cover the threat, which will likely continue into Tuesday with seas returning to 6-8 ft Wednesday.

The second half of the week is more active with trough dropping out of Alaska, and a couple of systems likely to affect the waters finishing the week into next weekend. Best chance of winds greater than 20 kt is with a system Wednesday/Thursday, Friday, and this weekend, affecting the coastal and interior waters. Seas will increase going towards the end of the week, peaking Friday with heights up to 15 to 17 ft.

HPR

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 1 AM Monday to 1 AM PST 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-West Entrance U.S. Waters Strait Of Juan De Fuca.