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Area Forecast Discussion (AFD)

Issued by Seattle/Tacoma, WA (SEW)

                            
519 
FXUS66 KSEW 152154
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
300 PM PDT Sun Jul 15 2018

.SYNOPSIS...Much above normal temperatures continue into Monday.
Cooler low level onshore flow will develop Tuesday and increase
Wednesday for several days with more normal temperatures.  

&&

.SHORT TERM...Skies remain sunny on this rather warm day--there
are thunderstorms in southern Oregon, but they wont make it this
far north. A few spots blew through the forecast highs again today, 
Forks was 86 at 2pm, but spots close to the water stayed cool, 
temps were in the upper 60s on the coastal beaches, and places 
like Eastsound on Orcas were about the same with a breeze off the
water. It is interesting to zoom in on the observation network and
see the contrasts--for instance, Copalis beach at 66 degrees with
the ob at Wishka less than 20 miles inland from there 95 degrees.

Monday will be another hot day--except along the coast, where the
sea breezes will become stronger each day from here on out. Low 
level onshore flow will increase Tuesday and Wednesday as the marine
layer deepens, and, with cooling aloft, we will get our fever back
down to normal for several days. Marine layer clouds will increase
at some point along the coast--probably just a few patches late 
tonight and Monday morning, but then for Tuesday and Wednesday 
mornings there should be night and morning low clouds and fog banks
on the coast--with fog and low clouds squirting into the Strait of 
Juan de Fuca too. Awfully clear out there today though--the fog and
low clouds that were partway up the Oregon coast earlier today burned
off, so we will see what happens along the coast overnight tonight, 
best rest assured, the natural AC will kick in pretty soon.

.LONG TERM...The cool down back near average temps midweek will give
Western Washington near average temps Wed-Friday, and then temps are
likely to turn a bit warmer again for next weekend. Areas of night 
and
morning clouds, mainly on the coast, should break up and diminish 
around
the end of the week. The trough moving through B.C. Thursday and 
Friday
should not give our area any precip--about the best we can hope for 
are
a few misty mornings on the coast and some dew at daybreak for the 
interior.

&&

.AVIATION...Weak westerly flow aloft will continue tonight and 
Monday. At the surface, a thermally induced trough of low pressure 
along the coast today will shift inland tonight. Weak offshore 
surface flow today will become more onshore tonight. The air mass 
across Western Washington will remain dry and stable today and 
tonight. VFR clear conditions are expected to continue, except some 
morning stratus is possible on the coast near KHQM.

KSEA...VFR clear. Northerly winds at the surface 5-10 kt. CHB

&&

.MARINE...Flow over the interior will be northerly or weakly 
offshore through Monday morning, giving lighter winds inland but 
still allowing advisory level northwest winds on the coast this 
afternoon and tonight. Winds over the inland waters including the 
strait are forecast to be northerly or offshore with speeds less 
than 20 kt. Wind in the strait will turn westerly this evening but 
remain below 20 kt. 

The flow will turn weakly onshore Monday, then increase Tuesday and 
Wednesday. Westerly gales are possible in the strait Wednesday. 
Moderate onshore flow will continue Thursday and Friday. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 PM PDT Monday 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 5 AM PDT Monday for Coastal Waters 
     From James Island To Point Grenville Out 10 Nm-Coastal 
     Waters From Point Grenville To Cape Shoalwater Out 10 Nm.

&&

$$

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