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Area forecast discussion 
National Weather Service Seattle Washington 
300 PM PDT Sat Jun 15 2019 


Synopsis...no significant weather systems will affect the area into 
the first part of next week. Marine layer clouds will occasionally 
spread into western Washington. An upper trough will reach the 
area around the middle of next week for a chance of showers, mainly 
in the Cascades. 


&& 


Short term /today through Monday/...marine clouds have receded to 
along the coast while the majority of West Washington is under sunny skies with 
a stray cloud here and there. Temperatures look to be on track with 
inherited forecast...with locations along the coast and Strait 
running at about what they were this time yesterday while interior 
locations running a few degrees warmer. 


Models remain pretty consistent regarding the short term...with the 
upper level ridge making its way east through the day Sunday. Both 
GFS and European model (ecmwf) are hinting at a shortwave disturbance within the 
ridge that might allow for some showers...but bulk of activity stays 
north of the border with only a little bit dipping down into the far 
northern Cascades...but even that looks more like it will impact the 
eastern slopes as opposed to the western slopes within the County Warning Area. 
Still...current forecast allows for a little spill-over in pops just 
in case. Flatter ridging will set up over the area Monday with high 
temperatures being identical to those expected tomorrow...lower to 
mid 60s along the coast...mid to upper 70s for the interior. 
Continued onshore flow will allow for overnight and early morning 
marine stratus to persist throughout the near term with sunny skies 
expected to emerge by afternoon. Smr 


Long term /Tuesday through Friday/...Tuesday appears to be nothing 
to write home about...although models are in a bit of disagreement 
with the European model (ecmwf) trying to bring in some showers in advance of the 
upper trough expected for Wednesday. The GFS hints at this...but 
does not bite on quite as hard as the European model (ecmwf). Opted not to go full 
bore on the European model (ecmwf) solution...but did go with high-end slight chance 
pops for now. This is where the models start to branch off...with 
the European model (ecmwf) bringing the upper level trough further south for 
Wednesday and Thursday...potentially bringing precip area-wide while 
the GFS seems convinced that the bulk of this feature will remain to 
the north with possibly some showers popping up over the Cascades. 
Given this uncertainty and...as per the previous shift...previous 
runs of the models were a bit more in lock step...decided to lean 
more into the inherited forecast while splitting the difference 
between the apparently now dueling models in the hopes that 
solutions might realign. Models agree on generally dry conditions 
for Friday but for different reasons...the European model (ecmwf) returns some 
ridging to the area while the GFS has a dry secondary trough in 
place. Smr 


&& 


Aviation...weak upper ridge axis over the offshore waters will 
shift onshore late today with light northwest flow aloft 
becoming westerly. The air mass is stable and dry with the 
exception of a marine layer along the coast that will push 
partially inland overnight. Areas of IFR in stratus/fog will develop 
at the coast this evening and move inland overnight...perhaps as far 
as the south end of Puget Sound and the Kitsap peninsula by 12z 
Sunday. VFR expected away from the immediate coast from mid-morning 
Sunday through the evening. 




Ksea...VFR continuing through the overnight hours. Expecting stratus 
to fall short of reaching ksea on Sunday morning, but it might get 
close around 12z-15z. Surface winds north to northwest 5 to 10 knots...becoming 
light and variable late tonight. 27 


&& 


Marine...high pressure over the coastal waters with lower 
pressure inland will result in varying degrees of onshore flow 
through the middle of next week. At least small craft westerlies 
will developing in the late afternoon/early evening hours in the 
central and eastern Strait of Juan de Fuca each day. A stronger 
onshore push Sunday evening has the potential to produce a westerly 
gale in the Strait and have decided to go with a gale watch there. 
Small Craft Advisory winds also expected over the coastal waters 
tonight as well as waters adjacent to the East Entrance of the 
Strait. 27 


&& 


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... 
Washington...none. 
Pz...Small Craft Advisory from 6 PM this evening to 5 am PDT Sunday 
for central U.S. Waters Strait of Juan de Fuca-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-East Entrance U.S. Waters 
Strait of Juan de Fuca-northern inland waters including the 
San Juan Islands. 


Gale watch from Sunday afternoon through late Sunday night for 
central U.S. Waters Strait of Juan de Fuca-East Entrance 
U.S. Waters Strait of Juan de Fuca. 


Small Craft Advisory from 6 PM this evening to 2 am PDT Sunday 
for Admiralty Inlet. 






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