textproduct: Seattle/Tacoma

UPDATE

First band of precipitation this morning now just north and west of Seattle moving slowly to the northwest. Second band just moving into Lewis County at 9 am/16z. This band will reach the Central Puget Sound late morning/early afternoon. Cloudy skies in between the precipitation bands. Convective temperatures late this afternoon in the upper 50s. Cloud cover will prevent temperatures from getting that warm which will limit the thunderstorm chances across the area. Current forecast has the trends covered. No forecast update this morning. See below for previous discussion and updated aviation section. Felton

SYNOPSIS

Wet and cooler conditions this weekend with a low off the coast. A stronger frontal system midweek will bring lowland rain, mountain snow, and breezy winds. Temperatures will cool further in the wake of this system before slowly warming back up for the second half of next week.

SHORT TERM /TODAY THROUGH MONDAY/

An upper level low will spin offshore today while pushing moisture north into western WA. This will lead to wetter conditions with rain through much of the day. Snow levels remain high over 5000 ft. Due to the clouds and rain we'll see cooler conditions with highs in the 50s. Rain will taper off this evening as the low slowly tracks inland to our south.

The upper low will spin over northern California on Sunday with just light showers over the mountains in western WA. Onshore flow will increase Sunday night as the low moves farther inland. Models hint at a possible convergence zone forming in Snohomish County with showers lingering overnight.

Onshore flow continues into Monday for more clouds and a chance of showers. Temperatures will track a few degrees cooler than average with highs in the lower to mid 50s. 33

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

Cooler and wetter conditions are favored moving into Tuesday and Wednesday as a deep upper low drops down from B.C. This period will bring lowland rain and mountain snow with snow expected at the mountain passes. Snow levels will hover around 3000 ft on Tuesday and drop to around 2000 ft on Wednesday. Expect highs in the 40s to lower 50s with lows in the 30s. We're under drier north flow Thursday and Friday as the low shifts southeast and a ridge builds offshore. South sound areas will see lows near freezing once again with potential for morning frost. 33

AVIATION

Southerly flow across western Washington as an upper level low offshore pushes showers up across the region. Conditions are beginning to transition to MVFR/IFR with some VFR cigs remaining. Will see a mixed bag of ceilings throughout the morning before returning back to VFR later this afternoon. Southerly winds 4 to 8 knots this morning becoming light after 00z.

KSEA...Ceilings have lowered to MVFR this morning. MVFR conditions will continue throughout the morning before improving to VFR by 21z. Southerly winds this morning 5 to 10 knots turning northerly after 00z.

Mazurkiewicz/McMillian

MARINE

Surface low pressure will move south of the coastal waters throughout today. No wind or sea impacts are expected with this system as it weakens throughout the weekend. Winds will generally remain calm and benign through the weekend. Westerly winds will slightly increase in the Strait late Sunday but look to be below small craft advisory threshold for now. A stronger frontal system arriving Tuesday into Wednesday will likely yield headlines with enhanced winds and seas.

Coastal seas 4 to 6 feet throughout the weekend. Seas will then start to build upwards to 8 to 10 feet by Tuesday evening and remaining elevated through Thursday.

Mazurkiewicz

HYDROLOGY

No river flooding is expected in the next seven days.

SEW WATCHES/WARNINGS/ADVISORIES

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