976
FXUS66 KSEW 131036
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
336 AM PDT TUE AUG 13 2013
.SYNOPSIS...HIGH PRESSURE ALOFT WILL PREVAIL OVER THE REGION
TODAY. A LOW PRESSURE SYSTEM WELL OFFSHORE WILL CONTINUE TO MOVE
TOWARD THE AREA TONIGHT AND WEDNESDAY. THIS WILL LEAD TO A CHANCE
OF RAIN ON THE COAST WEDNESDAY AFTERNOON AND ELSEWHERE WEDNESDAY
NIGHT. UNSETTLED CONDITIONS WILL PREVAIL ON THURSDAY DUE TO LOW
PRESSURE ALOFT.
&&
.SHORT TERM...
THERE WERE MAINLY MID LEVEL CLOUDS PRESENT OVER THE CWA EARLY THIS
MORNING...HOWEVER THERE WERE SOME BREAKS FOR PERSEID METEOR
SHOWER VIEWING.
MEANWHILE...HIGH PRESSURE ALOFT WILL PREVAIL OVER THE REGION TODAY
FOR TYPICAL MID-AUGUST WEATHER. THE MODELS WERE FASTER WITH THE
TIMING OF THE MATURE LOW PRESSURE SYSTEM WELL OFFSHORE AT THIS
TIME. LOOK FOR PRIMARILY MID AND HIGH CLOUDS TO INCREASE ACROSS
THE AREA LATER TODAY BUT MORE SO TONIGHT. RAIN IS EXPECTED ON THE
COAST LATE WED MORNING OR EARLY WED AFTERNOON... OVERSPREADING THE
REST OF THE AREA WED NIGHT. THE COLD FRONT ASSOCIATED WITH THIS
SYSTEM WILL LIKELY DISSIPATE AS IT MOVES ACROSS THE COASTAL WATERS
LATE WED NIGHT OR EARLY THU.
THE REGION WILL REMAIN UNDER THE INFLUENCE OF AN UPPER TROF ON
THU. THIS COMBINED WITH A 65-KNOT JET MOVING INTO THE AREA WILL
RESULT IN A THREAT OF SHOWERS ACROSS THE ENTIRE AREA. ALTHOUGH THE
AIR MASS WILL NOT BE THAT COOL...THE PRESENCE OF SHOWERS AND/OR
CLOUDS ON THU SHOULD KEEP TEMPS FROM CLIMBING ABOVE NORMAL.
.LONG TERM...
NO MAJOR CHANGES IN THE PATTERN ARE EXPECTED THROUGH DAY 5. AN
UPPER TROF WILL REMAIN OVER THE REGION FOR A CONTINUED RISK OF
SHOWERS...ALTHOUGH THE THREAT WILL LIKELY BECOME CONFINED TO THE
MOUNTAINS WITH TIME. HIGH PRESSURE ALOFT WILL GRADUALLY BUILD OVER
THE REGION EARLY NEXT WEEK FOR A RETURN TO TYPICAL SUMMERTIME
WEATHER.
&&
.AVIATION...LIGHT SOUTHWESTERLY FLOW ALOFT AND A STABLE AIR MASS
WILL REMAIN OVER WESTERN WASHINGTON THROUGH WEDNESDAY. LOW LEVEL
FLOW WILL REMAIN WEAKLY ONSHORE TODAY TRENDING TOWARDS WEAK OFFSHORE
BY TONIGHT.
THERE IS A LARGE CLOUD DECK ABOUT 4000-6000 FEET OVER MUCH OF THE
CENTRAL AND SOUTHERN PUGET SOUND...AND ITS EXPANDING INTO THE
CENTRAL COAST THIS MORNING. NORTHERN AREAS AND THE STRAIT ARE MOSTLY
CLEAR WITH PATCHY CLOUDS AND IT'S LIKELY THAT THE 5000 FOOT DECK
WILL EXPAND UP THERE AS WELL. ANY LOW CLOUDS THAT DEVELOP EARLY THIS
MORNING WILL FORM IN PLACE AS A FUNCTION OF LINGERING LOW LEVEL
MOISTURE AND COULD FORM ANYWHERE BETWEEN 300 AND 2000 FEET. KHQM HAS
JUST REPORTED BKN004.
KSEA...VFR CONDITIONS FOR THE EARLY MORNING HOURS WITH A 4000-5000
FOOT CLOUD DECK. IT IS POSSIBLE THAT A SHALLOW STRATUS LAYER WILL
DEVELOP THIS MORNING WITH CEILINGS ANYWHERE FROM 300 TO 2000
FEET...BUT REGARDLESS OF THE HEIGHT THEY SHOULD SCATTER OUT
AROUND 18Z.
&&
.MARINE...HIGH PRESSURE OVER THE OFFSHORE WATERS AND LOWER PRESSURE
EAST OF THE CASCADES WILL SUPPORT ONSHORE FLOW THROUGH THIS
EVENING. GRADIENTS LOOK A BIT WEAKER TODAY...SO WILL STICK WITH
JUST UNDER SMALL CRAFT WINDS THROUGH THE CENTRAL AND EAST STRAIT
LATE THIS AFTERNOON AND EARLY EVENING BEFORE THE FLOW TURNS WEAKLY
OFFSHORE AHEAD OF A WEAK FRONT THAT WILL MOVE THROUGH THE COASTAL
WATERS WEDNESDAY. LIGHTER GRADIENTS AND WINDS ARE LIKELY THURSDAY
FOLLOWED BY A SECOND WEAK SYSTEM ON FRIDAY.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT TIL 5 AM THIS MORNING FOR
THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA.
&&
$$
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