Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 092138
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
238 PM PDT WED APR 9 2014

.SYNOPSIS...HIGH PRESSURE ALOFT WILL PREVAIL OVER THE REGION
THROUGH THURSDAY. EXPECT THE TAIL END OF A WEAK DISTURBANCE
PASSING TO OUR NORTH TO CLIP THE AREA ON FRIDAY. HIGH PRESSURE
ALOFT WILL BUILD STRONGLY OVER THE REGION THIS WEEKEND FOR DRY
WEATHER WITH ABOVE NORMAL DAYTIME TEMPERATURES.

&&

.SHORT TERM...
WEAK HIGH PRESSURE ALOFT WILL PREVAIL OVER THE REGION THROUGH THU.
EXPECT THE TAIL END OF A SHORT WAVE TROF PASSING TO OUR NORTH TO
CLIP THE AREA ON FRI. THE MAIN IMPACT THIS WILL HAVE ON OUR WEATHER
WILL BE TO STRENGTHEN THE ONSHORE FLOW. THERE WILL ALSO BE A CHANCE
OF SHOWERS OVER THE COAST AND NORTH CASCADES. IT SHOULD REMAIN DRY
ELSEWHERE.

AN UPPER RIDGE WILL BUILD OVER THE PACIFIC NORTHWEST ON SATURDAY.
THIS COMBINED WITH LOW LEVEL NORTHERLY FLOW WILL RESULT IN
SOMEWHAT ABOVE NORMAL DAYTIME TEMPS AT A NUMBER OF PLACES...
ESPECIALLY THOSE AREAS FARTHEST FROM THE MAJOR WATER BODIES.

.LONG TERM...
THE MEDIUM RANGE SOLUTIONS WERE COMING INTO BETTER AGREEMENT IN
REGARDS TO THE SYNOPTIC FEATURES IMPACTING THE PACIFIC NORTHWEST
DURING THE EARLY PART OF THIS PERIOD...OR SUNDAY AND MON. THE
UPPER RIDGE IS ANTICIPATED TO REMAIN OVER THE AREA ON SUNDAY. THIS
COMBINED WITH LOW LEVEL OFFSHORE FLOW WILL RESULT IN WELL ABOVE
NORMAL TEMPS AT A NUMBER OF PLACES. DAYTIME READINGS COULD END UP
AS WARM AS THEY WERE THIS PAST MON.

IT LOOKS AS THOUGH MON WILL BE THE TRANSITION DAY. THE RIDGE AXIS
IS EXPECTED TO SHIFT EAST...ALLOWING ONSHORE FLOW TO RETURN. THUS
ANTICIPATE COOLER TEMPS ON MON AS WELL AS AN INCREASE IN CLOUDS.
HAVE CHOSEN TO FOLLOW MODEL TRENDS AND BACKED OFF ON THE RISK OF
PRECIP MON NIGHT. THE FORECAST NOW CONFINES IT TO MAINLY WITHIN A
PUGET SOUND CONVERGENCE ZONE.

BEYOND MON...THE MODELS DIVERGED CONCERNING THE DETAILS...SO
CONFIDENCE WAS NOT VERY HIGH. DECIDED TO LIMIT THE CHANCE OF
PRECIP TO MAINLY THE MOUNTAINS ON TUE. BEYOND TUE...THE OVERALL
PATTERN APPEARED UNSETTLED. DAYTIME TEMPS SHOULD FALL BACK TO
NEAR OR SLIGHTLY BELOW CLIMO BY THE MIDDLE OF NEXT WEEK.

&&

.HYDROLOGY...
RIVER FLOODING IS NOT EXPECTED ON AREA RIVERS...EXCEPT THE
STILLAGUAMISH...THE NEXT 7 DAYS.

A FLOOD WARNING REMAINS IN EFFECT UNTIL FURTHER NOTICE FOR THE
NORTH FORK OF THE STILLAGUAMISH RIVER IN SNOHOMISH COUNTY JUST
UPSTREAM OF THE SR 530 LANDSLIDE. FLOODING CONTINUED AS A RESULT
OF WATER POOLED BEHIND THE DEBRIS DAM THAT PARTIALLY BLOCKS THE
RIVER.

THE NORTH FORK OF THE STILLAGUAMISH NEAR ARLINGTON AND THE POOL
UPSTREAM OF THE SR 530 SLIDE WILL CONTINUE FALLING THROUGH THIS
WEEKEND.

&&

.AVIATION...THE FLOW ALOFT WILL BE NORTHWEST WITH LOW LEVEL ONSHORE
FLOW TODAY AND TONIGHT. AREAS OF LOW LEVEL MOISTURE WILL BURN OFF
LATER TODAY. OTHERWISE...THE AIR MASS IS DRY AND STABLE.

KSEA...LOW CLOUDS WILL SCATTER LATE THIS MORNING OR EARLY AFTERNOON.
LIGHT WIND BECOMING NORTHWEST 4-8 KNOTS THIS AFTERNOON. SCHNEIDER

&&

.MARINE...ONSHORE FLOW WILL PREVAIL THROUGH FRIDAY. WINDS WILL BE
GENERALLY LIGHT EXCEPT SMALL CRAFT ADVISORY WEST WINDS ARE LIKELY IN
THE CENTRAL AND EAST STRAIT EACH EVENING. OFFSHORE FLOW WILL DEVELOP
NEXT WEEKEND WITH A WEAK THERMAL TROUGH BUILDING ALONG THE COAST AND
HIGHER PRESSURE OVER INTERIOR BRITISH COLUMBIA. SCHNEIDER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNING REMAINS IN EFFECT FOR THE NORTH FORK OF THE
     STILLAGUAMISH RIVER EAST OF THE SR 530 LANDSLIDE.

PZ...SMALL CRAFT ADVISORY IN EFFECT UNTIL 5 AM THURSDAY FOR THE
     CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA.

&&

$$

WWW.WEATHER.GOV/SEATTLE

FOR THE GRAPHICAL AFD...VISIT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML




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