textproduct: Seattle/Tacoma

SYNOPSIS

Dry weather will continue across much of the region through the end of the week as a couple disturbances bypass the region. Temperatures will remain mild through the first half of the week, though a few areas next couple of mornings may see some instances of patchy fog. The next chance of precipitation comes with a potential front moving through next weekend, with snow levels dropping to around 4000 feet.

SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/

The latest forecast remains on track this evening with no updates. A large trough offshore is digging its way south towards California today. The surface low pressure system associated with the trough will also bypass the region to the south today into Tuesday. The weather will remain largely quiet thanks to the low and trough missing the region, and also a weak upper level ridge developing in western Canada today into Wednesday. Can't rule out some patchy fog potential with the high cloud deck thinning out and calm or light/variable winds, but the coverage will likely be limited to the valleys where it is cooler tonight. Some frost may also mix in, particularly in the south interior. The high clouds will dissipate late Tuesday, which should help bump up high temperatures a few degrees, as well as into Wednesday. The best chance for a 70 will be in the south interior.

LONG TERM /THURSDAY THROUGH MONDAY/

High pressure from Wednesday will move east on Thursday. A trough with a weak cold front will pass through Thursday into Friday. The best chance of precipitation will be for areas east of I-5, up to the Cascades. Temperatures will cool down a few degrees Thursday and Friday, with more 50s for highs, and some 30s in the valleys and mountains (which may also see a couple 20s). The models into next weekend remain in disagreement as to when and where another potential low will track through the region. Some have the system moving north up into Canada, and others have it deepening off the coast of B.C. This will keep precipitation chances somewhat a "tossup" going into the weekend, although snow levels either way are expected to drop to 4,000 to 5,000 ft going into weekend.

HPR

AVIATION

An upper level low will spin offshore to our SW tonight, with dry and stable weather over western WA. The flow aloft is southerly. VFR conditions expected tonight into Tuesday morning. The exception being where pockets of shallow fog develops, especially over the south Sound. Low clouds will burn off mid to late morning with VFR conditions expected on Tuesday. 33/29

KSEA...VFR conditions expected through the period. N winds 6-8 kt, becoming NE at 7-11 kt by 12-15z Tue decreasing in the evening to 4- 6 kt after 03z. Light and variable winds Tuesday night into Wednesday morning.

33/29

MARINE

Northerly flow will prevail over the waters with low pressure spinning off northern CA. Weak high pressure will result in generally light winds through mid week. Onshore flow will increase on Thursday/Thursday night as a cold front moves inland. Seas will rise on Thursday night and Friday with swells reaching 10-15 feet. Winds will turn offshore this weekend as deeper low pressure spins over the offshore waters.

33

SEW WATCHES/WARNINGS/ADVISORIES

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