textproduct: Seattle/Tacoma

SYNOPSIS

The low center off Vancouver Island will continue meandering south through Friday afternoon. As it weakens and moves inland on Saturday south of the area, conditions will begin to dry out. An upper level ridge will build on Sunday into early next week. Weak systems may arrive again by Wednesday.

SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/

Showers will taper down overnight as the offshore upper low shift farther west and southwest neat 130W. Freeze Watch was expanded to cover the Middle Chehalis River Valley Friday night. Otherwise, the rest of the forecast remains on track. 33

Previous discussion...Showers are moving inland throughout this afternoon as the center of the offshore low very slowly makes its way south. Some of these showers will produce more moderate rainfall, and it's still somewhat unstable, so there will be a slight chance of thunderstorms through this afternoon. Minimum temperatures will also be decreasing through Saturday morning. A Freeze Watch has been issued for the lowlands of Lewis and southern Thurston counties as overnight lows are forecast to be in the upper 20s to around 32 degrees. There is a chance that the middle Chehalis river valley may also need a freeze headline as lows there are approaching the upper 20s. Crops and sensitive vegetation may die as a result of temperatures that low, so take the proper precautions to protect things like that if needed.

Saturday will be partly sunny and drier, with no precipitation expected for any of the festivities taking place around the region. Highs will be in the mid 50s.

LONG TERM /SUNDAY THROUGH THURSDAY/

Weak ridging will be building in on Sunday, carrying through to the middle of the week. A series of weak systems will make it to the area through the end of the week but at this point are unlikely to create more than increased cloud cover. Precipitation is not expected to be significant if it occurs. Conditions will be fairly homogeneous through the week with periods of clouds and highs in the mid 50s.

The period of Nov 6 through 12 could feature a return to wetter conditions, but this will continue to be evaluated as it gets closer.

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AVIATION

An upper level trough will remain over the coastal and offshore waters into Friday producing south to southwest flow aloft over Western Washington. Scattered showers continue across the region this evening with mostly VFR ceilings. An overall decrease in shower activity is expected overnight...especially across interior areas. Another impulse rotating around the trough is expected to push onshore Friday morning for an increase in shower coverage and periods of MVFR ceilings. Decreasing showers and improving ceilings are expected late Friday afternoon or early evening.

KSEA...Ceilings are expected to remain at or above 4000 to 5000 feet this evening through the overnight hours. A general deterioration to MVFR ceilings is expected between 15Z and 21Z Friday as showers increase once again. Surface winds light and variable this evening will become E/NE generally 7 knots or less overnight into Friday morning.

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MARINE

Weak surface low pressure over the coastal waters will remain in place into Saturday before dissipating as high pressure builds across the interior of Western Washington early in the coming week. East or southeast winds across the coastal waters and near the west entrance to the strait will occasionally reach 15 to 20 knots over the next couple of days until the offshore low finally dissipates. Otherwise, winds into early next week look to remain rather light across area waters.

Coastal seas are expected to build back to around 10 feet by around Monday as another larger swell train reaches the waters.

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SEW WATCHES/WARNINGS/ADVISORIES

WA...Freeze Watch from late Friday night through Saturday morning for Lowlands of Lewis and Southern Thurston Counties- Middle Chehalis River Valley.

PZ...None.