textproduct: Seattle/Tacoma

SYNOPSIS

Surface high pressure will bring dry and mild conditions through Saturday to Western Washington. An upper level trough will move into the region Sunday through Monday and bring lowland rain and mountain snow. A brief break on Tuesday from precipitation, before another system arrives on Wednesday.

SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/

A weak system over British Columbia is bringing partly cloudy skies and isolated light showers to the coast and Olympic Peninsula. Otherwise, dry and mostly clear skies across the Western Washington this afternoon. Weak surface high pressure will continue over the region, keeping conditions dry and mild through Saturday. Expect high temperatures in the 50s and low temperatures in the 30s.

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LONG TERM /SUNDAY THROUGH THURSDAY/

High pressure will weaken on Sunday as an upper level trough passes over Western Washington through Monday, marking the return of lowland rain and mountain snow. At this time minor snow accumulations are expected at the passes with 2.00-4.00 inches possible. As for the lowlands, light rainfall amounts expected between 0.10-0.50 inches. A brief break in precipitation on Tuesday, before the next system arrives on Wednesday. Latest model solutions are in good agreement that an upper level low will move over Western Washington Wednesday through Thursday. However, at this time there are some disparities among models in terms of intensity of the low. High temperatures will generally be in the 50s next week. Low temperatures in the at the beginning of the week will be in the low to mid 30s and will increase slightly to the upper 30s and low 40s by late next week.

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AVIATION

Flow aloft remains westerly as a zonal pattern continues over the Pacific Northwest. A weak disturbance will remain north of the terminals today (expect a more scattered to broken cloud deck going north towards the Canadian border). Otherwise it will remain VFR regionwide through tonight and most terminals will see the VFR continue into Friday. There remains a 25-30% chance for patchy fog development from the south interior, up to the Kitsap Peninsula tonight/Friday morning. WInds will become variable this afternoon around 5 kt, becoming north/northeast this evening across most terminals. Winds increase to 4-8 kt Friday.

KSEA...VFR through tonight, then VFR likely Friday. There remains a low chance of any low ceiling/visibility development Friday, though a broken deck may fill in or near the terminal early Friday morning. Variable winds this afternoon will shift to the north/northeast. Speeds will drop to 5 kt or less tonight, and increase to 4-8 kt Friday.

HPR

MARINE

A weak system to the north will skirt the northern outer and interior waters this afternoon. High pressure will remain in place for the waters with a zonal flow/weak ridge overhead through the weekend. Winds will be light, with the direction being offshore at times. The next system skirts the outer coastal waters late next weekend, with the pattern becoming active again going into next week with showers/rain at times over the waters. The chance of any significant winds over the waters remains low, although a few areas in the outer coastal waters have a slight chance of seeing wind gusts at or over 20 kt.

Seas will remain at 6-8 ft Thursday through Sunday, decreasing to 4- 6 ft Sunday through Wednesday and further increasing to 6-8 ft Wednesday through next week Thursday.

HPR

HYDROLOGY

No river flooding expected in the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

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