279
FXUS66 KSEW 111558
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
858 AM PDT SAT JUL 11 2026
UPDATE
SATELLITE IMAGERY SHOWS PLENTY OF BREAKS IN THE CLOUD COVER
ESPECIALLY OVER THE NORTH COAST, STRAIT OF JUAN DE FUCA AND
CENTRAL CASCADE FOOTHILLS. MARINE LAYER IS SHALLOW WITH LIGHT
ONSHORE FLOW. EXPECT THE JULY SUNSHINE TO DISSIPATE THE LAYER IN
THE AFTERNOON. SOUTHWESTERLY FLOW ALOFT WITH UPPER LEVEL TROUGH
OFFSHORE WILL CONTINUE TO THROW MIDDLE AND HIGH LEVEL CLOUDS
OVER THE AREA THROUGH THE WEEKEND. MARINE LAYER REFORMING OVER
THE INTERIOR TOMORROW MORNING BUT LIKE TODAY THE LAYER WILL BE
SHALLOW MAKING FOR A SUNNY AFTERNOON. CURRENT FORECAST ON
TRACK. NO UPDATES THIS MORNING. PREVIOUS DISCUSSION FOLLOWS WITH
UPDATED AVIATION AND MARINE SECTIONS. FELTON
SYNOPSIS
AN UPPER LEVEL TROUGH WILL PRODUCE VARYING AMOUNTS OF CLOUD
COVER THROUGH THE WEEKEND ALONG WITH NEAR SEASONAL TEMPERATURES.
HIGH PRESSURE WILL REBUILD INTO THE REGION MONDAY AND TUESDAY
FOR A WARMING TREND. A WEAK SYSTEM MAY BRIEFLY COOL TEMPERATURES
AROUND THE MIDDLE OF THE COMING WEEK BEFORE A LONGER TERM DRY
AND WARM SPELL RETURNS TOWARD NEXT WEEKEND.
SHORT TERM /TODAY THROUGH MONDAY/
A UPPER LEVEL TROUGH JUST OFFSHORE WILL SEND A SERIES OF WEAK
DISTURBANCES ACROSS THE AREA INTO EARLY SUNDAY. FOR THE MOST
PART, DRY CONDITIONS WILL PREVAIL THOUGH A COUPLE LIGHT SHOWERS
WILL BE POSSIBLE AT TIMES ACROSS THE OLYMPIC PENINSULA, NORTH
INTERIOR, AND NORTH CASCADES. TEMPERATURES THROUGH SUNDAY WILL
HOVER WITHIN A COUPLE DEGREES OF SEASONAL NORMALS FOR MOST SPOTS.
THE UPPER TROUGH WILL LIFT BACK INTO BRITISH COLUMBIA LATER ON
SUNDAY AS STRONG UPPER RIDGING CENTERED OVER THE ROCKIES AND
NORTH GREAT PLAINS EXPANDS A LITTLE WESTWARD. WITH WEAKER
ONSHORE FLOW AND MODEST HEIGHT RISES, TEMPERATURES ON MONDAY
WILL EDGE UPWARD SEVERAL DEGREES WITH PLENTY OF SUNSHINE.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
THE DRY AND WARM TREND CONTINUES INTO TUESDAY. LOW LEVEL ONSHORE
FLOW WILL INCREASE A NOTCH OR TWO WHICH WILL COOL COASTAL AREAS
A BIT, BUT INTERIOR TEMPERATURES WILL REMAIN WARM WITH AREAS
AROUND SEATTLE METRO SEEING A 30-50% PROBABILITY OF MODERATE
HEATRISK.
UNCERTAINTY REMAINS IN THE TEMPERATURE TREND FOR THE LATER HALF
OF THE UPCOMING WEEK AS A NUMBER OF ENSEMBLE MEMBERS RETAIN SOME
DEGREE OF UPPER TROUGHING JUST OFFSHORE. BASED ON THE TRENDS OF
THE LAST FEW DAYS, THE MAIN EFFECT OF THIS WEAK TROUGH MAY BE
TO SIMPLY DELAY AN IMPENDING LENGTHY PERIOD OF ABOVE NORMAL
TEMPERATURES THAT MOST GUIDANCE POINTS TOWARD COMMENCING BY NEXT
WEEKEND.
27
AVIATION
VFR ACROSS THE AREA SO FAR THIS MORNING WITH THE EXCEPTION OF
ISOLATED MVFR LINGERING. ANY LINGERING LOW CLOUDS SHOULD IMPROVE TO
VFR BY 17-20Z. WINDS GENERALLY REMAIN LIGHT AND SOUTHWESTERLY,
INCREASING TO 8-10 KTS AFTER 18-21Z SAT THROUGH AROUND 06Z SUN.
KSEA...VFR CONDITIONS PREVAIL. SOUTHWEST WINDS CONTINUE BELOW 8 KT.
GUSTS NEAR 20 KT AFTER 00Z.
MARINE
A WEAK SURFACE TROUGH WILL REMAIN OVER THE OFFSHORE WATERS TODAY
BEFORE HIGH PRESSURE BROADLY REBUILDS INTO THE COASTAL AND OFFSHORE
WATERS SUNDAY AND MONDAY AND REMAINS IN PLACE INTO MIDWEEK. THIS
WILL PROMOTE A FAIRLY TYPICAL SUMMER PATTERN WITH VARYING DEGREES OF
ONSHORE FLOW PROMOTING A DIURNALLY DRIVEN INCREASE IN WESTERLIES
THROUGH THE STRAIT OF JUAN DE FUCA NEARLY DAILY. NORTHWEST WINDS
OVER THE COASTAL WATERS ARE LIKELY TO INCREASE LATER MONDAY INTO
TUESDAY AS THERMALLY INDUCED SURFACE LOW PRESSURE EXPANDING OVER THE
INTERIOR OF WESTERN WASHINGTON TIGHTENS THE ONSHORE GRADIENT.
FIRE WEATHER
THE CURRENT ONSHORE PATTERN WILL CONTINUE THROUGH THE WEEKEND
WHICH WILL LEAD TO CONTINUED EXCELLENT NIGHTLY RH RECOVERIES.
THERE'S A 30-40% CHANCE OF RAIN SHOWERS TODAY, MAINLY FOR THE
OLYMPICS AND NORTHERN CASCADES, BUT RAINFALL AMOUNTS DURING
THIS PERIOD WOULD GENERALLY TOTAL LESS THAN 0.10".
A RIDGE OF HIGH PRESSURE REBUILDS INTO THE REGION MONDAY AND
TUESDAY. WHILE THE ONSHORE PATTERN WILL LARGELY REMAIN IN PLACE,
WARMER DAYTIME TEMPERATURES AND CLEAR SKIES WILL LIKELY LEAD TO
RH VALUES DIPPING INTO THE 20-40% PERCENT RANGE, WITH THE
LOWEST VALUES IN THE SOUTH INTERIOR AND CASCADES VALLEYS. THIS
WILL ALLOW FINE FUELS TO CONTINUE TO DRY WITH ELEVATED FIRE
WEATHER CONDITIONS. SOME MODEST COOLING IS SLATED TO ARRIVE BY
THE MIDDLE OF NEXT WEEK, BUT MAY WELL BE SHORT-LIVED.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 3 AM PDT
SUNDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
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