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Area Forecast Discussion (AFD)

Issued by Seattle/Tacoma, WA (SEW)

                            
000
FXUS66 KSEW 252207
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
307 PM PDT Sat May 25 2019

.SYNOPSIS...Showers will end this evening as an upper low moves
south of the area. Drier and warmer weather is expected most of
next week with afternoon and evening showers over the Cascades 
most days. 

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...Showers will end from the
north this evening as an upper low tracking south through the
Coastal Waters moves south of the area.

The upper low will shift inland over the southwest U.S. Sunday and
Monday with an upper ridge off the coast. Western Washington will
be on the northern periphery of the upper low. There will be 
enough wrap around moisture and instability for a chance of 
afternoon and evening showers and thunderstorms over the Cascades 
each day with the aid of daytime heating. The low lowlands look 
mostly dry although a few showers could drift off the Cascades. 

A weak upper ridge will shift over the area on Tuesday but it 
won't make much difference for the weather. It should be another 
mostly sunny day. An isolated showers or thunderstorm could 
bubble up over the Cascades in the afternoon but the weak high
pressure aloft will probably cap things a bit.

Highs will warm several degrees on Sunday to slightly above 
normal and then warm a few more degrees on Monday with lower to 
mid 70s common. Highs will cool a few degrees on Tuesday due to
stronger low level onshore flow but remain a little above normal.
Schneider

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...It looks like a 
decidedly wishy-washy and uneventful pattern Wednesday through 
Saturday with a weak upper ridge on Wednesday giving way to a weak
upper trough Thursday and beyond. There won't be any organized 
weather systems but an isolated shower can't be ruled out at 
times. Temperatures will be a few degrees above normal each day 
with not much day to day variation. Schneider

&&

.AVIATION...Southeasterly flow aloft this afternoon will become 
easterly tonight as an upper level low slides south of the area. 
Surface slow will transition from onshore this afternoon to light 
northerly this evening into Sunday.

Cigs are generally MVFR to IFR currently with rain showers around as 
the upper level low moves through. Expect cigs to continue to be 
MVFR to IFR through the afternoon with some improvement to cigs late 
evening following 02z. Cigs will likely transition to VFR for a 
period tonight before lowering again during the early morning to 
MVFR to IFR with some low clouds around the area. Some fog is 
possible as well, mainly in prone areas. Southerly winds will 
transition to northerly late this afternoon into this evening. Winds 
5-10 knots.

KSEA...MVFR cigs through early this evening as showers continue. 
Expect improvement to cigs to VFR following 04z. VFR cigs for most 
of tonight will lower to MVFR again during the morning hours. 
Southerly winds will become northerly between 01z-03z. Winds 
generally 5-10 knots. JD

&&

.MARINE...Surface onshore flow will become light northerly tonight 
into Sunday. Small Craft Advisory winds over the coastal waters 
through this evening will ease to below 20 knots tonight. Flow will 
be light on Sunday with increasing onshore flow Monday and 
continuing through Wednesday. At least SCA level winds expected both 
Monday and Tuesday evening in the central and eastern Strait of Juan 
de Fuca. JD

&&

.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...Small Craft Advisory until 6 PM PDT 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.

     Small Craft Advisory for rough bar until 6 PM PDT this evening 
     for Grays Harbor Bar.

&&

$$

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