textproduct: Seattle/Tacoma

SYNOPSIS

Cool showery weather will lingering into Tuesday followed a dry pattern Wednesday and Thursday with near normal temperatures and foggy mornings. The next disturbance is expected to arrive by Friday, bringing rain and mountain snow, along with cooler conditions though the weekend.

SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/

Scattered showers will continue in the cool, unstable post- frontal air mass - with snow levels dipping to around 3000 feet will result in snow down at the passes with any lingering showers. Amounts are expected to be very limited as precipitation continues to taper off into Tuesday. Nonetheless, motorists traveling over the Cascades should expect to encounter winter conditions. With the cold air aloft there remains a 10-15% chance of isolated thunderstorms along or near the coast this afternoon.

Showers Tuesday Tuesday morning will fizzle out completely by midday, as upper level ridging begins to nose into western Washington. With all of the low level moisture, expect morning fog, especially in the favored locations clearing by late morning, with some sunshine in the afternoon. Cooler overnight temperatures especially outside of the metro area may result in many spots in the lower 30s and afternoon highs near 50. More clearing Tuesday night into Wednesday result in another round of morning fog on Wednesday.

LONG TERM /THURSDAY THROUGH MONDAY/

Ensemble guidance remains consistent with shortwave ridging only nosing into the Pacific Northwest through Thursday. Thursday looks to have another cool foggy morning. Ensembles do show some variability with the next system approaching the area late Thursday, with a mix of weaker and stronger scenarios. The common message remains lowland rain and mountain snow Friday with an unsettled pattern - defined by an upper level trough over much of the Pacific Northwest through the weekend. Many of the scenarios do show this upper level trough digging into northern California Sunday. This does suggest elevated odds of a colder - and potentially wet pattern affecting western Washington late in the weekend and early next week.

AVIATION

A surface trough will continue to produce showers across terminals this afternoon into tonight, with precipitation ending Tuesday. Brief IFR visibility drops continue with the heaviest showers. MVFR to VFR ceilings will continue to remain present through the afternoon/evening, with additional clearing taking place after sunset in the interior. Winds this afternoon will remain breezy at 8- 12 kt with a couple gusts to 20 kt - further decreasing to 3-6 kt tonight/Tuesday morning and shifting to the east/northeast before increasing to 5-10 kt out of the north in the afternoon. Probabilities for fog remain highest in the south interior, up to the Kitsap Peninsula, with the greatest coverage 12-18Z Tuesday morning. Mostly clear/VFR skies are expected Tuesday afternoon.

KSEA...VFR ceilings expected through tonight with a gradually lifting/clearing of lower clouds. All of the models cap probability of the fog at the terminal at 10% (0.5 mi), but with more broad development expected in sheltered/damp areas (especially to the west of the terminal), can't rule out some vicinity fog from 11-16Z (may be limited to more of a mist). Breezy southwest winds 8-12 kt gusting to 20 kt will decrease to 3-6 kt tonight out of the east, shifting to the north 5-10 kt late Tuesday morning.

HPR

MARINE

A weak surface trough over the waters will continue to produce showers this afternoon into tonight. No major winds are expected with this system, but a small craft advisory continues through tonight for the coastal waters for 8-10 ft seas. High pressure will move in Tuesday into Wednesday, keeping conditions dry, winds light out of the north/east, and seas 4-6 ft. A system will arrive Thursday into Friday, with additional systems pushing through this weekend into next week. A few windy periods are possible in the coastal waters, but confidence in small craft wind impacts remain low at this time. Seas however will rise up to 14-16 ft Friday, then decrease to 10-12 ft the remainder of the weekend into next week.

HPR

HYDROLOGY

River flooding is not expected during the next seven days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 10 PM PST this evening for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.