textproduct: Seattle/Tacoma

SYNOPSIS

Upper level ridge offshore weakening tonight. Increasing clouds Monday as a weak system moves through the ridge. Ridge rebuilding Monday night, moving inland Tuesday. Splitting system arriving Wednesday. More consolidated systems moving through Western Washington at the end of the week.

SHORT TERM /TODAY THROUGH TUESDAY NIGHT/

High pressure is still in control for more dry and stable conditions. We will see increasing mid/high levels clouds moving aloft tonight, due to a weak disturbance moving into B.C. Overnight lows will be a few degrees warmer as a result, however we will still see lows near freezing across the metro area. The ridge axis will shift inland Monday night, then cross western WA on Tuesday for one last dry day. The air mass is a little warmer with highs reaching the lower 50s. 33

LONG TERM /WEDNESDAY THROUGH SATURDAY/

A weak/splitting fronts moves inland on Wednesday for a chance of rain. Temperatures will moderate with lows around 40 and highs around 50. Snow levels are around 4,000-5,000 ft and the higher peaks and passes may see a few inches of snow. East winds may keep snow levels lower at Snoqualmie Pass with light freezing rain possible Wednesday afternoon and evening.

Western WA remains under moist, SW flow moving through the end of the week, with a return of lowland rain and mountain snow. Snow levels remain high, around 5,000 ft, with mixed precip rain/freezing rain/snow at Stevens Pass Friday (due to east winds). With a mild air mass in place, temperatures are tracking a few degrees warmer than average with highs in the lower to mid 50s and lows in mid 40s. 33

AVIATION

An upper level ridge will shift inland today into Monday, with a second ridge trailing immediately behind. Most terminals are VFR this afternoon (except for lingering fog at KOLM this afternoon, which is still trending on satellite towards clearing after 22Z). A brief trough in between ridges will produce high clouds tonight/Monday, thus reducing probabilities for fog redevelopment Monday morning (10% chance in the south interior). Winds remain light in the TAF period (less than 5 kt), but switch from north to south tonight/Monday (may also be light and variable at times).

KSEA...VFR through the TAF period. Clear through tonight with high clouds Monday. Winds less than 5 kt, will switch from northerly to southerly, but may be light and variable at times.

HPR

MARINE

Broad high pressure across the northeast Pacific will remain in place through the weekend with generally calm winds. The next period of impactful marine weather doesn't look to arrive until Tuesday, as a weak frontal system approaches the west coast and brings back increasing southerly winds that will likely reach Small Craft Advisory criteria across the coastal waters. A series of systems through mid to late week will keep breezy winds in the forecast Wednesday and beyond across all the area waters.

Seas 3 to 5 ft will continue this weekend, increasing to the 10-15 ft range Tuesday, getting as high as 18-20 feet on Wednesday, and remaining elevated at 9-13 feet through the remainder of next week as systems continue to traverse across the area.

62/15

HYDROLOGY

A return to wetter weather over the second half of the week will force rises on the Skokomish River in Mason County with minor flooding possible. No river flooding is anticipated elsewhere over the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...None.