Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 310415 CCA
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 PM PDT THU JUL 30 2015

.SYNOPSIS...A STRONG UPPER LEVEL RIDGE WILL BE OVER THE PACIFIC
NORTHWEST THROUGH SATURDAY. THE RIDGE WILL WEAKEN AND SHIFT A LITTLE
EAST SUNDAY INTO MONDAY. AN UPPER LEVEL TROUGH WILL MOVE OVER THE
AREA BY THE MIDDLE OF NEXT WEEK.

&&

.SHORT TERM...FOR THE INTERIOR OF WESTERN WA THERE WILL BE A COUPLE
MORE RATHER WARM DAYS AND THEN A COOLING TREND WILL BEGIN...SLOWLY
AT FIRST...ON SUNDAY. FORECAST HIGH TEMPS FOR FRIDAY RANGE FROM NEAR
80 AT HOQUIAM AND FORKS...TO THE 90S FROM THE SEATTLE METRO AREA
SOUTH. THE 850MB TEMP WILL PEAK AT 21C FRIDAY AFTERNOON AND THEN
FALLS OFF A COUPLE DEGREES SATURDAY AND A BIT MORE SUNDAY. CLEAR
SKIES WILL PREVAIL...THEN MAYBE A LITTLE HIGH CLOUDINESS WILL ARRIVE
SATURDAY NIGHT AND SUNDAY FOLLOWED BY LOW CLOUDS TO THE COAST
AND DEEPENING MARINE AIR SUNDAY NIGHT.

.LONG TERM...HIGHS TEMPS ON MONDAY OVER THE INTERIOR OF WRNW A WILL
FALL TO THE 70S TO LOWER 80S. AN UPPER LOW WILL DROP SE OVER THE
AREA MIDWEEK...WITH MORE COOLING AND AN INCREASING CHANCE OF SHOWERS
THROUGH THE END OF NEXT WEEK. THE 18Z GFS SHOWED A 563DM LOW CENTER
CROSSING NW WA THURSDAY.


&&

.AVIATION...AN UPPER RIDGE WILL CONT OVER THE REGION. CONTD WLY FLOW
ALOFT AND LOW LEVEL NW FLOW. PATCHY FOG IS POSSIBLE ALONG THE COAST
AFTER 0900 UTC.

KSEA...VFR. CONTD NLY WINDS.

&&

.MARINE...PERSISTENT HIGH PRES OFFSHORE WITH LOWER PRES E OF THE
CASCADES WILL KEEP THE FLOW NORTHWEST THROUGH FRI. EXPECT THE FLOW
TO BECOME MORE WESTERLY AND STRENGTHEN THIS WEEKEND, LEADING TO THE
POSSIBILITY OF GALE FORCE WINDS OVER THE CENTRAL AND EASTERN STRAIT
OF JUAN DE FUCA.

&&

.FIRE WEATHER...A CRITICAL PERIOD FOR FIRE WEATHER IS UNDERWAY...
GIVEN HOW EXTREMELY DRY THE AIR MASS IS OVER WESTERN WASHINGTON.
MANY LOCATIONS ARE EXPERIENCING RELATIVE HUMIDITY DOWN IN THE 20S
THIS AFTERNOON...EVEN LOCATIONS THAT NORMALLY STAY MORE HUMID SUCH
AS NEAR THE STRAIT OF JUAN DE FUCA. WHEN YOU GET ABOVE A LOW-LEVEL
SUBSIDENCE INVERSION NEAR 2000 FEET MSL...THE AIR MASS IS ALSO MORE
UNSTABLE. WITH THAT ADDITIONAL AGGRAVATING FACTOR...WILL KEEP THE
RED FLAG WARNING GOING FOR ELEVATIONS ABOVE 2000 FEET. LOOKS LIKE
LITTLE CHANGE IN THE CHARACTER OF THE MID-LEVEL AIR MASS UNTIL
SATURDAY EVENING...SO HAVE EXTENDED THE RED FLAG WARNING UNTIL 10 PM
SATURDAY. THIS IS THE KIND OF WEATHER SETUP THAT HELPS SMALL FIRES
GROW TO BECOME LARGE FIRES.HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES... WA...HEAT ADVISORY REMAINS IN
EFFECT TIL 9 PM SATURDAY FOR PARTS OF THE PUGET SOUND REGION AND
SOUTHWEST INTERIOR.

     RED FLAG WARNING IN EFFECT TIL 10 PM SATURDAY NIGHT FOR THE
CASCADES AND OLYMPICS ABOVE 2000 FEET.

PZ...SMALL CRAFT ADVISORY REMAINS IN EFFECT TONIGHT FORTHE COASTAL
     WATERS FROM JAMES ISLAND TO CAPE SHOALWATER OUT TO 10 NM AND
  THE CENTRAL AND EASTERN STRAIT.

&&

$$

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