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Area Forecast Discussion (AFD)

Issued by Seattle/Tacoma, WA (SEW)

                            
000
FXUS66 KSEW 241003
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
303 AM PDT Fri May 24 2019

.SYNOPSIS...A low will drop south from British Columbia today, 
bringing a chance for light showers across the area, with isolated
thunder possible near Cascade crest. Another low drops south for 
Saturday with more widespread chances for showers. Drier and 
warmer weather expected for the lowlands for next week with 
chances for showers and isolated thunderstorms in the mountains 
through Memorial Day. 

&&

.SHORT TERM /TODAY THROUGH SUNDAY/...Well we had a little
excitement early this morning as small convergence zone fired off
a line of showers and thunderstorms from Port Clinton over to Lake
Stevens/Everett and east into Snohomish County. Plenty of
lightning strikes to go along with heavy downpours and possible
small hail. Further north, showers beginning to drop south from BC
as first of two lows approaches. This system will drop south
across WA today and into Oregon tonight. Latest hi-res guidance 
suggests most activity will be across the mountains and lowlands 
east of the Sound so have nudged forecast in that direction. Some 
areas won't see any rain at all today. Outside of showers, cloud 
cover, breezy winds, and cooler air will reign. Afternoon 
temperatures will top out in the upper 50s to lower 60s.

Second low will take a track further west and skirt the 
Washington coast Saturday, dropping into northern California by 
Sunday. This may allow for more widespread showers on Saturday. 
Temperatures will be similar to today, maybe a degree or two 
warmer. 

Low then departs for Sunday, bringing drier weather for the
lowlands and temperatures warming back into the 70s. Much like 
the past few days, still a chance for some showers and isolated 
thunderstorms across the mountain as long wave western US trough 
remains in place with a bit of instability. CEO

.LONG TERM /MONDAY THROUGH THURSDAY/...Ridging builds in next week
with a return to dry weather and warm temperatures. Will likely 
see periods of morning clouds and afternoon sun. Memorial Day 
highs will top out in the mid to upper 70s with low to mid 70s for
the rest of the week. Pattern suggests we may continue to see 
diurnally driven showers and isolated thunderstorms in the 
mountains each day through mid-week. CEO

&&

.AVIATION...Light flow aloft today becoming northwesterly tonight
as upper level trough moves south of the area. Low level onshore
flow into Saturday. In general ceilings between 1000-2000 feet
except along the Strait of Juan de Fuca and over the Northwest 
Interior where ceilings will be in the 5000 foot range. Ceilings
lifting a little this afternoon into tonight before lowering back
down to 1000-2000 feet Saturday morning. 

KSEA...Ceilings between 1000-2000 feet lifting to 2000 to 3000
feet midday then lowering back down overnight. Southerly wind 10
to 15 knots. Felton

&&

.MARINE...Onshore flow continuing into Saturday with strong
northwesterly flow over the coastal waters. Gale warnings are in
effect for the outer coastal waters with small craft advisories
for the inner coastal waters. Winds easing later Saturday into 
Sunday as the low level flow becomes light. Onshore flow will 
increase again on Monday and continue into Tuesday. Felton


&&

.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated as needed
until then.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Gale Warning until 2 PM PDT Saturday for Coastal Waters From 
     Cape Flattery To James Island 10 To 60 Nm-Coastal Waters 
     From James Island To Point Grenville 10 To 60 Nm-Coastal 
     Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm.

     Small Craft Advisory until 6 PM PDT Saturday for Coastal Waters 
     From Cape Flattery To James Island Out 10 Nm-Coastal Waters 
     From James Island To Point Grenville Out 10 Nm-Coastal 
     Waters From Point Grenville To Cape Shoalwater Out 10 Nm.

     Small Craft Advisory until 6 PM PDT this evening for West 
     Entrance U.S. Waters Strait Of Juan De Fuca.

&&

$$

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