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Area Forecast Discussion (AFD)

Issued by Seattle/Tacoma, WA (SEW)

FXUS66 KSEW 242236

Area Forecast Discussion
National Weather Service Seattle WA
336 PM PDT Thu May 24 2018

.SYNOPSIS...An onshore flow pattern will prevail for the next
several days for night and morning clouds and partial afternoon
sunshine most days. An upper trough could bring some showers
around the middle of next week.


.SHORT TERM...An upper trough will move over the area Friday but 
it looks dry. Low level onshore flow will continue for night and 
morning clouds and partial afternoon sunshine. Highs will be near 
normal. More of the same is expected for Saturday and Sunday with 
low level onshore flow continuing. A weak upper short wave could 
bring some drizzle Saturday morning. Temperatures will be near 
normal Friday and Saturday. Rising upper heights and slightly 
weaker onshore flow will allow highs to warm a few degrees on 
Sunday. Schneider

.LONG TERM...An upper trough will gradually settle over the area
for the first half of next week with low level onshore flow
continuing. There are no fronts or organized weather systems
expected but there will be slight chance of showers Tuesday and
beyond. By Thursday the models become quite inconsistent adding to
the uncertainty and justifying low chance PoPs for now. Schneider


.AVIATION...Tail end of a weak upper level trough will brush by
Western Washington late Friday. Moderate southwest flow aloft,
becoming westerly on Friday evening. Low-level onshore flow will
keep advecting a moist marine layer onshore, with dry and stable
air above. Marine clouds will fill back into the lowlands late
tonight, burning off again around mid-day Friday.

KSEA...A light north wind will slowly develop over the next few 
hours, but it will likely take until after about 04z for it to get
as strong as 6 kt. Once northerly wind develops, a northerly
component should continue into Friday evening. Cloudwise, late 
tonight and Friday morning, a higher deck of marine clouds will 
affect the terminal, with cigs mainly between 025 and 030. Should 
have no trouble burning off the marine clouds by mid-day Friday. 


.MARINE...Varying degrees of moderate to strong onshore gradients
and westerly flow will continue through the Memorial Day weekend
and into early next week. Forecasting high-end small craft
advisory strength westerlies through the Strait this evening,
though gales are still possible. On Friday evening, UIL-BLI 
gradient should peak around +3.5 to +4.0 mb, so forecasting 
westerly gales through the Strait Friday evening. High-end small 
craft winds are expected during the late afternoon and evening 
each day this weekend, though gales are certainly possible on just
about any evening. Haner


PZ...Gale Watch from Friday afternoon through late Friday night for 
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance 
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 4 PM PDT Friday for Central U.S. 
     Waters Strait Of Juan De Fuca-East Entrance U.S. Waters 
     Strait Of Juan De Fuca.

     Small Craft Advisory until 4 AM PDT Friday for Admiralty Inlet-
     Northern Inland Waters Including The San Juan Islands.

     Small Craft Advisory until 6 AM PDT Friday for Coastal Waters 
     From Point Grenville To Cape Shoalwater Out 10 Nm.