Small Craft Advisory 759, NWS Seattle, WA

AREA FORECAST DISCUSSION...CORRECTED TO REMOVE SECOND MARINE SECTION
NATIONAL WEATHER SERVICE SEATTLE WA
907 AM PDT SUN JUL 3 2011

.SYNOPSIS...AN UPPER LEVEL TROUGH COMBINED WITH POST FRONTAL ONSHORE
FLOW WILL GIVE SCATTERED SHOWERS TODAY...MAINLY TO THE CASCADES AND
AROUND A CENTRAL PUGET SOUND CONVERGENCE ZONE. SKIES WILL BEGIN
CLEARING LATER TONIGHT AS HIGH PRESSURE BUILDS INTO THE AREA. HIGH
PRESSURE WILL BUILD INTO THE AREA INDEPENDENCE DAY THROUGH MIDWEEK
GIVING DRY WEATHER WITH HIGH TEMPERATURES A LITTLE ABOVE NORMAL. AN
UPPER TROUGH WILL LIKELY SETTLE OVER THE REGION LATER IN THE WEEK
FOR SOMEWHAT COOLER AND CLOUDIER WEATHER.

&&

.SHORT TERM...THE FRONTAL SYSTEM THAT CROSSED WESTERN WASHINGTON
EARLY THIS MORNING IS MOVING RAPIDLY EASTWARD ACROSS EASTERN
WASHINGTON AT 800 AM. MODELS APPEAR TO HAVE OVER PREDICTED THE
COVERAGE OF SHOWER ACTIVITY...ALL THAT IS LEFT THIS MORNING IS ALONG
THE WEST SLOPES OF THE NORTH CASCADES AND AROUND A PUGET SOUND
CONVERGENCE ZONE FROM ADMIRALTY INLET AND NORTH OF EVERETT TO
ARLINGTON AND THE NORTH CASCADES. THE CONVERGENCE ZONE WILL SLIDE
SOUTHWARD INTO THE SNOHOMISH AND KING COUNTY AREAS DURING THE
DAY...AND WILL DIE OUT EARLY THIS EVENING FROM THE CENTRAL SEATTLE
AREA EAST TO AROUND SNOQUALMIE PASS. TEMPERATURES WILL REMAIN IN THE
LOWER TO MID 60S IN THE CONVERGENCE ZONE AREA...AND WILL RISE INTO
THE UPPER 60S ELSEWHERE.

WITHS SOME CLEARING...EXPECT COOL CONDITIONS TONIGHT WITH
TEMPERATURES AROUND 50 IN URBAN AREAS AND MID 40S IN OUTLYING
VALLEYS.

TEMPERATURES ALOFT WARM UP ON MONDAY WITH 850 MB TEMPERATURES
REACHING 10C AROUND 00Z TUE. THIS SUPPORTS HIGH TEMPERATURES IN THE
LOWER TO MID 70S AROUND MUCH OF WESTERN WASHINGTON WITH SUNNY SKIES
DURING THE AFTERNOON HOURS ON INDEPENDENCE DAY.

WEAK UPPER RIDGING WITH LIGHT ONSHORE FLOW AND 500 MB HEIGHTS RISING
TO THE MID 580 DAM RANGE TUESDAY SUPPORTS TEMPERATURES RISING
ANOTHER 5-6 DEGREES...A FEW PLACES REACHING 80 DEGREES.

THE FORECASTS WERE UPDATED THIS MORNING TO REDUCE SHOWER COVERAGE TO
SCATTERED IN THE CONVERGENCE ZONE AREA AND ALONG THE WEST SLOPES OF
THE CASCADES...AND ISOLATED SHOWERS ELSEWHERE. THE REMAINDER OF THE
FORECAST IS ON TRACK. ALBRECHT

.LONG TERM...PREVIOUS LONG RANGE DISCUSSION FOLLOWS...EXTENDED
MODELS ARE IN GOOD AGREEMENT FOR WEDNESDAY WITH THE FLAT UPPER LEVEL
RIDGE WEAKENING A LITTLE. MODEL SOLUTION DIVERGE AFTER WEDNESDAY
WITH THE ECMWF BRINGING A MUCH STRONGER TROUGH THROUGH WESTERN
WASHINGTON ON THURSDAY...500 MB HEIGHTS DROPPING DOWN INTO THE MID
560 DAM...WHILE THE GFS KEEPING THE HEIGHTS ABOVE 570 DAM. WITH THE
STRONGER TROUGH THE ECMWF IS A LITTLE SLOWER KICKING THE TROUGH OUT
TO THE EAST THURSDAY NIGHT AND FRIDAY. GFS ENSEMBLES SHOW THE
OPERATION RUN IS ACTUALLY ONE OF THE MORE PESSIMISTIC SOLUTIONS SO
WILL STAY WITH JUST THE MORNING CLOUDS AFTERNOON SUN SCENARIO FOR
WEDNESDAY AND THURSDAY. A LITTLE BETTER AGREEMENT INTO NEXT WEEKEND
WITH WEST NORTHWEST FLOW ALOFT AND LOW LEVEL ONSHORE FLOW. 500 MB
HEIGHTS ARE ONLY IN THE LOWER TO MID 570 DAM SO WILL CONTINUE THE
MORNING CLOUDS AFTERNOON SUN FORECAST INTO NEXT WEEKEND WITH HIGHS
NEAR OR A LITTLE BELOW NORMAL. FELTON

&&

.AVIATION...WLY FLOW ALOFT WILL PREVAIL OVER THE REGION THRU
TONIGHT. CONTINUED LOW LEVEL ONSHORE FLOW. MEANWHILE...CIGS WERE
GENERALLY IN THE 1-3K FT RANGE /TOPS 5-6K FT/ THIS MORNING...
ALTHOUGH THERE WERE A FEW AREAS DEVOID OF CLOUDS AT THIS TIME.
EXPECT CIGS TO LIFT INTO THE VFR CATEGORY RANGE THIS AFTERNOON...
WITH CLOUDS BECOMING SCATTERED ACROSS MUCH OF THE AREA.

KATX DOPPLER RADAR SHOWED A SW TO NE ORIENTED CONVERGENCE ZONE
/ROUGHLY SW OF KPAE TO NE OF KAWO/ AT THIS TIME. THE CONVERGENCE
ZONE SHOULD REORIENT ITSELF LATE THIS MORNING OR EARLY THIS
AFTERNOON TO ITS TYPICAL LOCATION BETWEEN KPAE AND N OF KBFI BEFORE
DRIFTING S AND DISSIPATING LATE TODAY OR EARLY THIS EVENING.

KSEA...THE PUGET SOUND CONVERGENCE ZONE IS EXPECTED TO SHIFT S OVER
THE TERMINAL THIS AFTERNOON OR BETWEEN 2100 UTC AND 0000 UTC MON.
THUS THERE WILL PROBABLY BE A SHORT PERIOD WHERE WINDS WILL BE NLY
AT KBFI AND FROM THE SW AT KSEA. EXPECT THE WINDS TO BECOME NLY AT
THE TERMINAL ABOUT 0000 UTC. MEANWHILE...CIGS WILL BE IN THE VFR
CATEGORY TODAY BUT THERE MAY BE OCCASIONAL MVFR CIGS THIS MORNING.

&&

.MARINE...
HIGH PRES JUST OFF THE WASHINGTON COAST AND LOWER PRES E OF THE
CASCADES WILL RESULT IN CONTINUED ONSHORE FLOW OF VARYING STRENGTH
THROUGH TUE. EXPECT WINDS TO RISE TO LOW END SMALL CRAFT ADVISORY
SPEEDS OR 20-25 KNOTS OVER MAINLY THE CENTRAL STRAIT OF JUAN DE FUCA
DURING MAINLY THE AFTERNOONS AND EVENINGS.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL MIDNIGHT TONIGHT FOR THE CENTRAL
      AND EASTERN STRAIT OF JUAN DE FUCA.

&&

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