Small Craft Advisory 790, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
254 PM PDT THU AUG 4 2011

.SYNOPSIS...LOOK FOR LOW CLOUDS TO OVERSPREAD THE LOWLANDS TONIGHT...
REACHING THE LOWER SLOPES OF THE CASCADES FRIDAY MORNING. THE MORNING
CLOUDS SHOULD GIVE WAY TO SOME SUNSHINE IN THE AFTERNOON...ALTHOUGH
THE COAST WILL LIKELY REMAIN CLOUDY ALL DAY. LOOK FOR FAIRLY SIMILAR
CONDITIONS ON SATURDAY...WITH LESS CLOUD COVER EXPECTED ON SUNDAY.
THIS WILL BE DUE TO WEAKER ONSHORE FLOW. DAYTIME TEMPERATURES WILL
RUN A LITTLE BELOW NORMAL FRIDAY AND SATURDAY BUT WILL CLIMB BACK
TO NORMAL ON SUNDAY.

&&

.SHORT TERM...
THE ONSHORE PRES GRADIENT CONTINUED TO TIGHTEN THIS AFTERNOON AND
THIS HAS PREVENTED MUCH CLEARING OVER THE COAST. LOOK FOR LOW
CLOUDS TO OVERSPREAD THE LOWLANDS LATER TONIGHT DUE TO A STRONGER
ONSHORE GRADIENT AND A DEEPER MARINE LAYER.

MOST LOWLAND SITES WILL START OFF CLOUDY TOMORROW MORNING BUT
THERE SHOULD BE SOME SUNSHINE IN THE AFTERNOON. THE EXCEPTION WILL
BE THE COAST WHERE CLOUDS WILL LINGER. OF COURSE...DAYTIME TEMPS
ON FRI WILL BE SEVERAL DEGREES COOLER AT MOST PLACES THAN TODAY.
HAVE WENT CLOSER TO THE GFS MOS TEMPS AS THE NAM SEEMED A BIT TOO
WARM FOR FRI.

THERE WILL NOT BE MUCH CHANGE IN THE OVERALL PATTERN OVER THE PAC
NW THRU THIS WEEKEND. A WEAK UPPER TROF WILL PREVAIL OVER THE
REGION BUT WILL NOT HAVE A SIGNIFICANT IMPACT ON OUR WEATHER. THE
ONSHORE GRADIENT WILL REMAIN RELATIVELY TIGHT THRU SATURDAY BEFORE
RELAXING SATURDAY NIGHT AND SUNDAY. THUS ANTICIPATE A GRADUAL TREND
TOWARD LESS NIGHT AND MORNING CLOUD COVER THIS WEEKEND...WITH
DAYTIME TEMPS REBOUNDING TO ABOUT NORMAL ON SUNDAY.

.LONG TERM...
ANTICIPATE TYPICAL AUGUST WEATHER DURING THIS PERIOD...THAT IS
AREAS OF NIGHT AND MORNING LOW CLOUDS MAINLY OVER THE COAST AND
NEAR CLIMO TEMPS. THE LONG WAVE PATTERN OVER THE PAC NW IS NOT
EXPECTED TO UNDERGO MUCH CHANGE.

&&

.AVIATION...A WEAK UPPER LEVEL TROUGH WILL GRADUALLY SHIFT ONSHORE
TONIGHT AND FRIDAY. LOW LEVEL ONSHORE FLOW WILL INCREASE A BIT IN
RESPONSE. LOW CLOUDS CURRENTLY AT THE COAST WILL SPREAD INLAND
TONIGHT...THEN BURN BACK TO THE COAST FRIDAY AFTERNOON. AIR MASS
STABLE EXCEPT SLIGHTLY UNSTABLE OVER THE CASCADES DURING THE
AFTERNOON AND EVENING HOURS.

KSEA...NORTHWEST WIND 6-10 KNOTS THIS AFTERNOON AND EVENING WILL
BECOME SOUTHERLY 3-6 KNOTS AFTER MIDNIGHT TONIGHT. LOW CLOUDS WILL
PROBABLY REACH THE TERMINAL AROUND DAYBREAK. SCHNEIDER

&&

.MARINE...ONSHORE FLOW WILL PRODUCE SMALL CRAFT ADVISORY WEST WINDS
FOR THE CENTRAL STRAIT AND EAST ENTRANCE EACH DAY INTO EARLY NEXT
WEEK. WINDS WILL PEAK LATE AFTERNOON THROUGH EARLY MORNING HOURS
MOST DAYS. WHILE DAY TO DAY DIFFERENCES ARE SUBTLE...IT APPEARS THE
ONSHORE FLOW WILL BE STRONGEST THIS EVENING AND AGAIN FRIDAY EVENING
AND GALE FORCE WEST WINDS ARE NOT OUT OF THE QUESTION FOR THE
CENTRAL STRAIT AND EAST ENTRANCE DURING BOTH DAYS. IT IS A CLOSE
CALL AND HAVE A 20 TO 30 KNOTS FORECAST FOR THIS PERIOD FOR NOW.
SCHNEIDER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT SATURDAY FOR CENTRAL U.S.
     WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS
     STRAIT OF JUAN DE FUCA.

&&

WWW.WEATHER.GOV/SEATTLE

FOR THE GRAPHICAL FORECAST DISCUSSION...PLEASE GO TO
WWW.WRH.NOAA.GOV/SEW/GAFD/LATEST_WEBAFD.HTML