Small Craft Advisory 1124, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
1049 AM PST THU NOV 29 2012

.SYNOPSIS...A SERIES OF PACIFIC STORMS WILL IMPACT THE REGION
THROUGH THIS WEEKEND FOR WET AND UNSETTLED WEATHER AS WELL AS
LOCALLY WINDY CONDITIONS.

&&

.SHORT TERM...
A LITTLE BUSY THIS MORNING DUE TO RAPIDLY CHANGING CONDITIONS.

THE TIDE WAS RUNNING HIGHER THAN PREDICTED AT LA PUSH THIS MORNING.
THE RESULT WILL BE THAT THE HIGH TIDE AROUND NOON TODAY WILL END UP
OVER 9.5 FEET. THIS COMBINED WITH SEAS RUNNING 16 TO 18 FEET WILL
CREATE THE POTENTIAL FOR COASTAL FLOODING IN THE LA PUSH AREA. THUS
A COASTAL FLOOD WATCH WAS ISSUED FOR THIS AREA.

THE COLD FRONT WAS MOVING ACROSS THE CWA AT THIS TIME. KLGX
INDICATED NOT MUCH PRECIP BEHIND THE FRONT EXCEPT FOR A BAND OF
SHOWERS WELL OFFSHORE. THERE WAS A LIGHTNING STRIKE ASSOCIATED WITH
THE SHOWERS OFF THE SOUTH COAST. IN ADDITION TO THE LACK OF PRECIP
BEHIND THE FRONT...VISIBLE SATELLITE IMAGERY SHOWED BREAKS IN THE
OVERCAST JUST OFFSHORE. THIS WILL EVENTUALLY TRANSLATE INLAND.
UPDATED THE FORECAST TO CUT BACK ON POPS FOR THIS AFTERNOON AND
EVENING AS WELL AS DECREASED THE CLOUD COVER.

TEMPS WERE ALSO RUNNING WARMER THAN PREDICTED ACROSS SOME AREAS...
ESPECIALLY THE FAR NORTH INTERIOR WHERE A FEW SITES JUMPED TO ABOUT
60 DEGREES DUE TO DOWNSLOPE FLOW OFF THE CASCADES. TEMPS SHOULD PEAK
THIS MORNING AND THEN LEVEL OFF OR REMAIN ABOUT THE SAME THE REST OF
TODAY. FOR THOSE AREAS EXPERIENCING DOWNSLOPE FLOW...TEMPS WILL
ACTUALLY FALL AS THE WIND SHIFTS TO SOUTHERLY. THIS HAS ALREADY
HAPPENED IN THE BELLINGHAM AREA.

MOIST SOUTHWEST FLOW ALOFT WILL CONTINUE OVER THE REGION THROUGH
THIS EVENING FOR A RISK OF PRECIP...ESPECIALLY OVER THE MOUNTAINS.
THE PRECIP WILL INCREASE LATER TONIGHT AS THE NEXT UPPER SHORT WAVE
AND ASSOCIATED UPPER TROF APPROACHES THE AREA. BOTH WILL MOVE ACROSS
THE CWA ON FRI FOR MORE WET WEATHER AND LOCALLY WINDY CONDITIONS.
YET ANOTHER SYSTEM WILL IMPACT THE REGION ON SATURDAY FOR MORE OF
THE SAME.

.LONG TERM FROM THE PREV DISCUSSION...
EXTENDED MODELS IN FAIRLY GOOD AGREEMENT THIS MORNING IN THE LARGE
SCALE FEATURES BUT AS HAS BEEN THE CASE FOR THE LAST THREE MORNINGS
THERE ARE SOME BIG DIFFERENCES IN THE SMALLER SCALE FEATURES. ALL OF
THE MODELS INDICATING THE TROUGH AXIS MOVING THROUGH ON SUNDAY WITH
THE JET AIMED AT NORTHERN CALIFORNIA SO WESTERN WASHINGTON WILL NOT
GET THE HEAVIEST PRECIPITATION WITH THE FEATURE.

THERE HAS BEEN LITTLE CONSISTENCY BOTH RUN TO RUN AND BETWEEN THE
MODELS ON THE TRACK OF THE SURFACE LOW FOR SUNDAY.  WHILE THE
SURFACE LOW MOVING THROUGH WESTERN WASHINGTON SCENARIO THAT WAS
PRESENT ON THE ECMWF TWO NIGHTS AGO IS GONE THERE IS A WEAKER LOW ON
THE ECMWF WITH SOME DECENT PRESSURE RISES BEHIND IT COULD RESULT IN
A WINDY DAY. THE 00Z GFS RUN LEAVES THE LOW MORE TO THE SOUTH AND IS
A LITTLE WEAKER WITH THE PRESSURE RISES. THE 06Z NAM HAS A 986 MB
LOW NEAR PORTLAND AT 18Z ON SUNDAY. FOR NOW WILL STAY WITH THE
BROADBRUSH RAIN AT TIMES FORECAST AND NOT MENTION ANY WIND.

ALL OF THE MODELS TRY AND BUILD A WEAK RIDGE OVER THE AREA ON MONDAY
BUT NONE OF THE MODELS ARE DRY ON THE 00Z RUN FOR MONDAY. THE NEXT
SYSTEM ARRIVING ON TUESDAY INTO WEDNESDAY. PREVIOUS RUNS HAD A NICE
SUB TROPICAL MOISTURE TAP WITH THESE SYSTEM. THE MODELS ARE SLOWLY
BACKING AWAY FROM THAT SCENARIO THIS MORNING BUT STILL ANOTHER WET
COUPLE OF DAYS FOR THE REGION TUESDAY AND WEDNESDAY. FELTON

&&

.HYDROLOGY FROM THE PREV DISCUSSION...
WITH THE JET SAGGING SOUTH OVER THE WEEKEND THE THREAT OF FLOODING
FOR THE SKOKOMISH RIVER IS DECREASING. WITH THE SYSTEMS MOVING
THROUGH WESTERN WASHINGTON WITH BREAKS IN THE PRECIPITATION POST
FRONTAL THE SKOKOMISH RIVER HAS STAYED BELOW 15 FEET. THERE IS THE
POTENTIAL FOR SOME HEAVIER PRECIPITATION ALONG THE SOUTH SLOPES OF
THE OLYMPICS WITH THE NEXT TWO SYSTEMS WHICH WILL KEEP THE THREAT OF
SOME MINOR FLOODING ON THE SKOKOMISH RIVER LATER FRIDAY INTO
SATURDAY.

FOR THE FIRST HALF OF NEXT WEEK THE EXTENDED MODELS ARE STARTING TO
BACK OFF THE ATMOSPHERIC RIVER SCENARIO FOR TUESDAY AND WEDNESDAY.
THE ECMWF STILL SHOWS AN 18-24 HOUR PERIOD OF POSSIBLE HEAVY
PRECIPITATION SO WE ARE STILL IN WAIT AND SEE MODE. THE 00Z RUNS
WOULD SUGGEST THE GREATEST THREAT IS ONCE AGAIN FOR THE SKOKOMISH
RIVER AND TO LESSER EXTENT THE RIVER FLOOD PRONE RIVERS FLOWING OFF
THE CASCADES. FELTON

&&

.AVIATION...THE DEEP LOW PRESSURE SYSTEM OFFSHORE WILL SPIN OFF A
SERIES OF FRONTAL BANDS THROUGH THE END OF THE WEEK. ONE OF THESE
FRONTS IS MAKING ITS WAY THROUGH WESTERN WASHINGTON THIS MORNING.
AREAS OF RAIN WILL CONTINUE. THE AIR MASS IS MOIST AND STABLE. THE
FLOW ALOFT IS SSW AND AND ABOVE 850MB REMAINS PRETTY CONSTANT
THROUGH THE DAY TODAY AT AROUND 45KT. 19/SMR

KSEA...A FRONTAL BAND WILL MOVE THROUGH THE AREA THIS MORNING...SO
CIGS MAY DROP AT TIMES THIS MORNING. THE PRECIP IS EXPECTED TO
CHANGE TO SCATTERED SHOWERS THIS AFTERNOON AND TONIGHT. THE TIME
HEIGHT CROSS SECTION FOR SEATTLE SHOWS LITTLE CHANGE BETWEEN TODAY
AND FRIDAY. 19/SMR

&&

.MARINE...THE DEEP LOW PRESSURE SYSTEM OFFSHORE WILL SPIN OFF A
SERIES OF FRONTAL BANDS THROUGH THE END OF THE WEEK. ONE OF THESE
FRONTS IS CURRENTLY MOVING THROUGH WESTERN WASHINGTON THIS MORNING.
THE GALES ARE EXPECTED TO CONTINUE IN ALL THE NORMAL SPOTS...COASTAL
WATERS...ENTRANCES TO THE STRAIT...NORTHERN WATERS...AND WILL START
TO SUBSIDE BY LATE MORNING...BUT MAY HOLD ON TIL MIDDAY OVER
THE EAST ENTRANCE AND NORTHERN INLAND WATERS. THE NEXT DISTURBANCE
WILL COME THROUGH THE AREA LATER TONIGHT AND FRIDAY...THAT DOESN'T
SEEM LIKELY TO HAVE AS MUCH PUNCH AND MIGHT ONLY GET THE WIND UP TO
30KT IN THE NORMAL WINDIER SPOTS. 19/SMR

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...COASTAL FLOOD ADVISORY REMAINS IN EFFECT FOR THE LAND AREAS
     ADJACENT TO THE PUGET SOUND/HOOD CANAL WATERS...ADMIRALTY
     INLET..AND NORTHERN INLAND WATERS.

     COASTAL FLOOD WATCH IN EFFECT FOR THE LA PUSH AREA THROUGH
     FRIDAY MORNING.

PZ...GALE WARNINGS ARE IN EFFECT FOR THE COASTAL WATERS...ENTRANCES
     TO THE STRAIT OF JUAN DE FUCA...AND THE NORTHERN INLAND WATERS.

     SMALL CRAFT ADVISORY IN EFFECT FOR THE REMAINING WATERS UNTIL
     1 PM THIS AFTERNOON.

     SMALL CRAFT ADVISORY IN EFFECT FOR ROUGH GRAYS HARBOR BAR
     CONDITIONS UNTIL 10 AM FRIDAY.

&&

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