Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
FXUS66 KSEW 231616
Area Forecast Discussion
National Weather Service Seattle WA
916 AM PDT SAT JUL 23 2016
.SYNOPSIS...High pressure will bring dry and mild weather this
weekend into Monday. A weak system will move by to the north
Monday night bringing some marine air into the interior for
Tuesday. The ridge will strengthen Wednesday into the end of the
week with the warmest temperatures of the month expected.
.SHORT TERM...There is patchy light rain and drizzle this morning
in the interior with overcast skies across much of Western
Washington, due to an onshore push overnight. But the low level
stratus layer should break up this afternoon as a ridge starts to
build in. Skies will become mostly sunny this afternoon with
highs in the upper 60s coast and low to mid 70s in the interior.
Onshore flow will be weaker tonight with stratus clouds mainly
affecting the coast. The interior should remain mostly clear for a
sunny start to Sunday. The upper level ridge will remain over the
Pac NW and we will see temps rise a few more degrees. Highs will
be in the mid 70s to lower 80s in the interior with lower 70s on
The ridge will flatten on Monday but 500 mb heights are still high
in the 580s. Temperatures will likely remain a few degrees above
normal, similar to Sunday. Onshore flow will increase Monday night
as a weak cold front passes through. The stronger onshore push
will bring stratus clouds farther inland Tuesday morning, and also
push temperatures down a few degrees. 33
.LONG TERM...Previous discussion...Warmest days of July coming up
the latter half of next week. Extended models in good agreement
with a very weak shortwave moving by to the north Monday night.
This will thicken up the marine layer over Western Washington a
little Tuesday morning and result in slightly cooler high
temperatures...up to 5 degrees cooler versus Monday. Flat upper
level ridge begins strengthening Wednesday with 500 mb heights
near 590 dms by Friday. Surface gradients remaining northwesterly
and onshore through the period. This will put a cap on the high
temperatures. Highs on Wednesday will be in the 70s to mid 80s
with about 5 degrees of warming on Thursday. Highs on Friday will
be similar to Thursday. The warmer locations Thursday and Friday
will be near 90. There is a good chance Seattle gets to 85
Thursday and Friday for the first time this month. Last year there
were a record tying 12 days in July with highs 85 plus in Seattle.
July 2014 had 11 days with highs 85 plus. Felton
.CLIMATE...Tomorrow ( July 24 ) is the driest day in Seattle
weather records. Since records started in the 1890`s there has
only been a total of 0.72 inches of rain recorded on the 24th.
There is only one other day in the year...July 30th with 0.75
inches of rain...where there has been less than an inch of rain.
.AVIATION...High pressure aloft will remain over the area through
tonight. Northerly winds aloft will weaken with time. Contd low
level onshore flow. There were areas of MVFR CIGs this morning.
Expect VFR conditions over the entire area by 2000 UTC.
KSEA...Expect ocnl MVFR CIGs this morning. Light and variable
winds will become nly less than 10 knots this afternoon.
.MARINE...High pressure offshore with lower pressure east of the Cascades
will maintain onshore flow of varying strength through Tuesday.
The flow will strengthen on Monday for the possibility of gale
force winds over parts of the Strait of Juan de Fuca.
PZ...Small Craft Advisory until 3 AM PDT Sunday for Central U.S.
Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
Strait Of Juan De Fuca.
You can see an illustrated version of this discussion at