145
FXUS66 KSEW 131619
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
919 AM PDT MON JUL 13 2026
SYNOPSIS
HIGH PRESSURE ALOFT WILL REBUILD ACROSS THE REGION
INTO TUESDAY FOR WARM AND DRIER CONDITIONS. AN AREA OF LOW
PRESSURE MAY BRING A THREAT OF SHOWERS AND THUNDERSTORMS AROUND
MIDWEEK BEFORE HIGH PRESSURE REGAINS CONTROL TOWARD THE WEEKEND
FOR A RETURN OF DRY CONDITIONS AND WELL ABOVE NORMAL
TEMPERATURES.
SHORT TERM /TODAY THROUGH WEDNESDAY/
MOSTLY CLEAR CONDITIONS
EXIST ACROSS WESTERN WASHINGTON THIS MORNING. HIGH PRESSURE
ALOFT WILL CONTINUE TO BUILD OVER THE REGION TODAY AS AN AREA OF
LOW PRESSURE DIGS SOUTHWARD OFFSHORE. THE WARMING TREND
CONTINUES INTO TUESDAY AS THE RIDGE CONTINUES TO STRENGTHEN OVER
THE AREA WITH THE OFFSHORE TROUGH BECOMING CUT- OFF. HIGH
TEMPERATURES WILL GET INTO THE 80S FOR INTERIOR
AREAS...ESPECIALLY SEATTLE SOUTHWARD...WITH PORTIONS OF THE
SEATTLE-TACOMA AREA GETTING INTO LIKELY MODERATE HEATRISK. WARM
TEMPERATURES FOR INTERIOR AREAS CONTINUE INTO WEDNESDAY WITH THE
RIDGE IN PLACE FOR CONTINUED LIKELY MODERATE HEATRISK FOR A
LARGE SWATH OF THE SEATTLE-TACOMA CORRIDOR.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
UNCERTAINTY IN
THE FORECAST BECOMES A SIGNIFICANT FACTOR BY THURSDAY AS MODELS
CONTINUE TO STRUGGLE WITH THE PATH OF THE CUT-OFF LOW OFFSHORE.
A SIGNIFICANT PORTION OF THE ENSEMBLES, ESPECIALLY THE SUITE OF
ECMWF SOLUTIONS, SUGGEST A CONTINUED THREAT OF SHOWERS AND/OR
THUNDERSTORMS ON THURSDAY COUPLED WITH A BRIEF COOL DOWN.
NEGATIVELY TILTED LOWS SUCH AS THIS OFTEN HAVE A WAY OF
INITIATING ELEVATED INSTABILITY WITH NO DEFERENCE TO THE TIME OF
DAY. THIS WILL CONTINUE TO POSE A FIRE WEATHER CONCERN AND NEED
TO BE MONITORED CLOSELY.
ONCE THIS SYSTEM EXITS THE AREA, MODELS REMAIN PRETTY LOCKED IN
WITH STRONG UPPER RIDGING FOR AN EXTENDED PERIOD OF WELL ABOVE
NORMAL TEMPERATURES AND DRY CONDITIONS FOR THE WEEKEND AND
BEYOND.
27
AVIATION
SOUTHWESTERLY FLOW ALOFT WILL PERSIST INTO TUESDAY.
SURFACE WINDS GENERALLY LIGHT AND VARIABLE ALTHOUGH SOME
TERMINALS REPORTING NORTHERLY WINDS 4-8 KTS. BY THIS AFTERNOON,
MOST TERMINALS SHOULD BE REPORTING SIMILAR DIRECTION AND
SPEED...WITH SOME VARIANCES TO THE NORTHEAST OR NORTHWEST.
SOME HIGH CLOUDS IN PLACE OVER W WA THIS EARLY MORNING WITH VAST
SWATHS OF CLEAR SKIES. OTHERWISE, VFR CONDITIONS ARE EXPECTED
FOR REMAINING TERMINALS THROUGHOUT THE FORECAST PERIOD.
KSEA...VFR THROUGHOUT THE PERIOD. N/E WINDS 5-10 KTS EARLY THIS
MORNING, AND LIKELY TO REMAIN THAT WAY INTO THE AFTERNOON
BEFORE A SLIGHT SHIFT TO THE NW BY 22Z. RETURNING NORTHERLY WITH
SPEEDS EASING SLIGHTLY TO 4-8 KTS THIS EVENING AND OVERNIGHT
WITH VFR CONTINUING.
18/MAZURKIEWICZ
MARINE
SURFACE HIGH PRESSURE OVER AREA WATERS THROUGHOUT THE
NEXT FEW DAYS. DIURNAL WESTERLY WINDS THROUGH THE STRAIT OF
JUAN DE FUCA WILL BE THE MAIN THEME. SPEEDS FOR THE MOST PART
LOOK TO REMAIN BELOW SCA CRITERIA, WITH TONIGHT BEING THE
EXCEPTION WHERE SPEEDS LOOK TO RUN 15-25 KTS. AS SUCH, A SMALL
CRAFT ADVISORY HAS BEEN ISSUED STARTING LATE THIS AFTERNOON AND
RUNNING INTO TONIGHT. COASTAL WATERS MAY ALSO SEE WIND GUSTS
APPROACH 20 KT TOWARDS THE END OF THE WEEK ON THURSDAY AND
FRIDAY WITH ANOTHER LOW SYSTEM TRACKING THROUGH THE WATERS.
SEAS FOR THE MAJORITY OF THE FORECAST WILL REMAIN AT 4-6 FT, WITH
THE SYSTEM THURSDAY/FRIDAY INCREASING SEAS TO 7-8 FT WITH PERIODS
AROUND 6-8 SECONDS.
41/18
FIRE WEATHER
WARMING TEMPERATURES THIS WEEK WILL INCREASE
THE FIRE WEATHER RISKS GOING INTO THE WEEKEND. A POTENTIAL CUT-
OFF LOW PRESSURE SYSTEM ARRIVING AROUND MIDWEEK REMAINS A
CONCERN FOR CONVECTION AND ASSOCIATED RISKS OF LIGHTNING STRIKES
WITH FUELS NOW RUNNING QUITE DRY.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 1 AM PDT
TUESDAY FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-
EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
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