textproduct: Seattle/Tacoma

SYNOPSIS

Drier conditions will emerge over the weekend as upper-ridging builds into the region. The trend will last to start the work week but won't persist. The next weather system arrives by the middle of next week with lowland rain and mountain snow.

SHORT TERM /TODAY THROUGH MONDAY/

Surface high pressure over W WA leading to mostly calm winds observed so far this morning. As a result, patchy morning fog is developing with most of the coverage expected over the Chehalis River valley. For today, we'll begin to see pattern progression as an upper low well offshore gently tracks eastward. The aforementioned low center is becoming ingested into the mean- flow before looming just off the CA/OR coast on Sunday with upper-level ridging over the Gulf of Alaska. Slight PoPs may sneak their way into SW WA on Sunday however, conditions are slated to remain mostly dry and trend that way into Monday as the ridge axis begins to position overhead. High temperatures are to top out in the upper 40s to near 50 F with overnight lows cooling into the 30s each night.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

An upper-ridge continues over the PNW on Monday night. The next front looks to arrive by Tuesday evening with a chance of widespread lowland rain and mountain snow. Afterwards, conditions are forecast to remain active into Friday. At this time, the potential for significant weather hazards appears low and the precipitation looks primarily beneficial for the region, adding some much needed snow to the snowpack in the mountains. That said, given a weak favoring of above normal temperatures, snow levels may limit the overall additions.

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AVIATION

West to northwest flow aloft will continue through today with weak upper ridging centered offshore. Low-end VFR cigs continue early this morning, with localized MVFR especially around Puget Sound, and some clearing elsewhere. This trend will continue through this morning, with localized areas of LIFR/IFR around KOLM with any fog development. Any areas of low cigs will improve to VFR by late morning with high clouds at times, with the exception being around KCLM where MVFR cigs may exist early this afternoon. Light winds this morning will increase from the north and range 5 to 12 kts this afternoon.

KSEA...Low-end VFR cigs early this morning. Cigs may lower into MVFR, mainly between 13 to 17z. The probabilities of MVFR cigs peaks around 20% during this period. Otherwise, low end VFR will scatter for high clouds during the afternoon. Light winds will increase from the NE around 12z, and north winds will further increase in the afternoon, ranging between 7 to 12 kts later today. JD

MARINE

A surface ridge will settle over the interior portions of British Columbia today. Winds will increase from the north today, with a northerly to weakly offshore component through this weekend. Winds are generally expected to remain below SCA criteria, although a few gusts over the outer Coastal Waters may reach 20 kts this afternoon through tonight. The next frontal system will move into the waters Tuesday into Wednesday for the return of increased southerly winds and potential headlines.

Seas of 7 to 9 feet will slowly subside to 4 to 6 feet tonight through Sunday. Seas will range 3 to 5 feet on Monday before building again Tuesday. JD

HYDROLOGY

No river flooding is expected during the next seven days.

SEW WATCHES/WARNINGS/ADVISORIES

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