120
FXUS66 KSEW 302249
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
345 PM PDT MON JUN 30 2025
SYNOPSIS
HIGH PRESSURE ALOFT WILL MAINTAIN WARM AND DRY
CONDITIONS ACROSS THE REGION EARLY THIS WEEK. AS THE HIGH
PRESSURE WEAKENS TOWARD MIDWEEK, EXPECT A RETURN TO NEAR NORMAL
TEMPERATURES. MOST AREAS REMAIN DRY THROUGH THE WEEK, THOUGH A
FEW SHOWERS ARE POSSIBLE NEAR THE COAST AND MOUNTAINS BY THE END
OF THE WEEKEND.
SHORT TERM /TONIGHT THROUGH THURSDAY/
CLEAR SKIES OVER W WA THIS
AFTERNOON AS UPPER LEVEL RIDGING REMAINS THE DOMINANT WEATHER
INFLUENCE OVER THE REGION. TEMPS AS OF 3 PM RUNNING THE RANGE FROM
LOWER TO MID 70S FOR WATER ADJACENT LOCATIONS WHILE SOME OBS ON THE
ISLANDS ARE STILL DOWN IN THE MID TO UPPER 60S. INTERIOR LOCATIONS
ARE FEELING THE HEAT THOUGH WITH MOST LAND-BASED OBS IN THE MID TO
UPPER 80S.
WITH THE RIDGE AXIS MOVING FURTHER EAST, CENTERING OVER ID TUESDAY,
W WA WILL BE ON THE BACKSIDE OF THE FEATURE AND AS SUCH, WILL SEE
TEMPS START TO COOL BUT TEMPS WILL START TO COOL, ALBEIT GRADUALLY.
AN APPROACHING UPPER LEVEL TROUGH WILL HELP TO ENHANCE ONSHORE
PUSHES, WHICH WILL HELP TAKE THE EDGE OF TEMPS MORE SIGNIFICANTLY
WEDNESDAY AND THURSDAY, WITH DAYTIME HIGHS GENERALLY IN THE LOWER TO
MID 70S FOR THE INTERIOR AND MID TO UPPER 60S FOR COASTAL AND WATER-
ADJACENT LOCATIONS.
THIS PAIRING OF THE UPPER LEVEL TROUGH AND ONSHORE FLOW WILL ALLOW
FOR SOME MOISTURE TO INCREASE OVER THE AREA, MAINLY IN THE FORM OF
SOME CLOUDS...BUT NO PRECIP IS EXPECTED FOR MUCH OF W WA. SOME
ISOLATED SHOWERS MAY BE POSSIBLE OVER PORTIONS OF THE CASCADES
WEDNESDAY AND THURSDAY WITH A SHORTWAVE DISTURBANCE, BUT OTHERWISE
THIS FEATURE SHOULD HAVE MINIMAL IMPACT.
18
LONG TERM /FRIDAY THROUGH MONDAY/
CONFIDENCE IN THE
SPECIFICS OF THE PATTERN LATE IN THE WEEK, INCLUDING THE
INDEPENDENCE DAY HOLIDAY, REMAINS RATHER LOW WITH ENSEMBLE
GUIDANCE CONTINUING TO EXHIBIT A RATHER LARGE SPREAD IN HOW THE
PATTERN MAY EVOLVE. THE FORECAST CONTINUES TO REFLECT THE MOST
LIKELY SCENARIO OF A GENERALLY ZONAL FLOW PATTERN THAT WILL
PROVIDE FOR SOME MORNING CLOUDS AND TEMPERATURES CLOSE TO (OR
SLIGHTLY ABOVE) SEASONAL NORMALS. THIS WOULD LEAVE THE DOOR OPEN
TO PERHAPS A FEW LIGHT SHOWERS NEAR THE NORTHERN COAST AND IN
THE NORTH CASCADES OVER THE WEEKEND, BUT EVEN IN THESE FAVORED
LOCATIONS THE CHANCE OF RAIN REMAINS QUITE LOW (LESS THAN 20
PERCENT) FOR THE WEEKEND. 12
AVIATION
THE AIR MASS IS DRY AND STABLE ACROSS WESTERN WA WITH
BROAD RIDGING OVER THE PAC NW. LOW LEVEL STRATUS CLOUDS WILL PUSH
INLAND TONIGHT, THROUGH THE CHEHALIS GAP AND STRAIT, FOR MVFR TO IFR
CONDITIONS. EXPECT VFR CONDITIONS IN THE INTERIOR. 33
KSEA...VFR TONIGHT AND TUESDAY WITH N WINDS TO 10 KT. 33
MARINE
A THERMAL TROUGH ALONG THE COAST WILL LEAD TO GUSTY
WINDS AND CHOPPY SEAS OVER THE COASTAL WATERS - A SMALL CRAFT
ADVISORY REMAINS IN EFFECT. EXPECT STRONG WESTERLY PUSHES DOWN THE
STRAIT OF JUAN DE FUCA TONIGHT, TUESDAY NIGHT AND WEDNESDAY NIGHT.
GALES ARE POSSIBLE IN THE STRAIT TUESDAY NIGHT. A WEAK FRONT WILL
CROSS THE WATERS ON WEDNESDAY, WITH ONSHORE FLOW FOLLOWING THROUGH
THE END OF THE WEEK. 33
FIRE WEATHER
WARM AND DRY CONDITIONS WILL CONTINUE ACROSS THE
REGION THROUGH WEDNESDAY UNDER HIGH PRESSURE. DAYTIME RH VALUES WILL
CONTINUE TO DIP TO AROUND 30-35% ACROSS THE CASCADES, AND CENTRAL
PUGET SOUND SOUTHWARD. A FEW SPOTS IN THESE AREAS MAY SEE RH DROP TO
25%, WITH ELEVATED FIRE WEATHER CONCERNS (PARTICULARLY IN DRY GRASSY
AREAS). LIGHT WINDS OUT OF THE NORTH TO NORTHEAST IS EXPECTED WITH A
SLIGHT BREEZE IN THE AFTERNOONS. TUESDAY MORNING WILL HAVE A MODEST
RH RECOVERY OVERNIGHT/MORNING. AS A DEEPER MARINE PUSH BEGINS TO TAP
IN SOME MARINE AIR WEST OF PUGET SOUND WEDNESDAY, A FEW AREAS EAST
OF THE SOUND MAY STILL STAY DRIER, WITH RECOVERIES IMPROVING MORE ON
THURSDAY. MODEL GUIDANCE HAS THE ONSHORE FLOW WITH COOLER
TEMPERATURES AND HIGHER RH'S CONTINUING THROUGH THE HOLIDAY WEEKEND.
THE BIGGEST UNCERTAINTY WILL BE IF ANY SHOWERS ARE ABLE TO DEVELOP
WITH WEAK TROUGHS PUSHING THROUGH.
HPR
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT TUESDAY FOR CENTRAL U.S.
WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH LATE TUESDAY NIGHT FOR
CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE
U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT TUESDAY 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 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.
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