Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

543
FXUS66 KSEW 251015
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
315 AM PDT Tue Jul 25 2017

.SYNOPSIS...Upper level ridging will keep sunny skies and warmer
temperatures over the region today, except for some isolated morning
low clouds near the coast. Increasing onshore flow this evening will
result in more clouds and cooler weather Wednesday and Thursday. A
transition to southwest flow aloft and weaker onshore flow will
result in mild and dry weather this weekend into early next week.

&&

.SHORT TERM...Skies remain mostly clear over much of W WA this early
morning. Current satellite shows maybe a few isolated patches of low
clouds here and there...but overall the reality is not really
syncing up with what models project with regards to stratus
development along the coast. Morning forecast will keep coastal
clouds in for now...as development may occur as we get closer
sunrise.

Late morning should see the return of clear skies over most of the
area as an upper level ridge makes its way eastward over the area
and as such...another warm day is on tap with interior afternoon
high temperatures generally 1-3 degrees warmer than yesterday. In
the wake of this ridge...onshore flow will strengthen in advance of
some weak upper level troughiness for Wed...which will kick off a
bit of a cooling trend. Interior afternoon highs will fall to right
around 80 Wed and will drop into the mid to upper 70s Thu.

Friday appears to be transitional with mostly zonal flow over the
CWA. As non-committal as the day might be in the war of ridge vs
trough...it does look like temps will start to nudge upward by a
degree or two.

Still no real indication of any sort of rainfall...as any upper
level lows that pass by will do so off to the north. SMR

.LONG TERM...Saturday shows a shortwave upper level ridge over the
area...but its impact to the area seems pretty minimal as high temps
Sat are nearly identical to those of Fri. For Sun...models once
again toy with the prospect of an upper level low and...as has been
the case for the past couple of weeks now...once again yoinks the
system just out of reach to the north. This pattern remains in place
into the start of next week...where next Monday sees a shortwave
ridge over the area and next Tuesday has yet another system pass to
the north.  So it looks like the dry streak will continue for the
foreseeable future unless model solutions start shifting southward.
Given how locked into place the monsoonal pattern is over the desert
southwest...the chances for that southward shift look to be
minimal.  SMR

&&

.AVIATION...A broad upper level ridge will bring dry and stable
conditions to Western Washington today. The flow aloft is NW to
W. Low level stratus clouds will likely form along the coast
this morning for IFR to MVFR conditions. VFR conditions will
prevail in the interior. 33

KSEA...Clear skies and N winds to 08 kt. 33

&&

.MARINE...High pressure over the NE Pacific will maintain onshore
flow across Western WA through Friday. Westerly gales are possible
through the Strait of Juan de Fuca Wednesday night with a stronger
onshore push. A weak front will pass through the Coastal Waters
Saturday night. 33

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 PM this afternoon to 1 AM PDT
     Wednesday for 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 AM PDT Wednesday 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 from 5 PM this afternoon to 5 AM PDT
     Wednesday for Central U.S. Waters Strait Of Juan De Fuca-
     East Entrance U.S. Waters Strait Of Juan De Fuca.

&&

$$

www.weather.gov/seattle

You can see an illustrated version of this discussion at
www.wrh.noaa.gov/sew/gafd/latest_webafd.html



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.