Special Weather Statement

North Oregon Coast (Oregon)
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PORTLAND OR
618 AM PST TUE DEC 29 2009
ORZ001-002-WAZ021-292230-
NORTH OREGON COAST-CENTRAL OREGON COAST-SOUTH WASHINGTON COAST-
INCLUDING THE CITIES OF...ASTORIA...CANNON BEACH...TILLAMOOK...
LINCOLN CITY...NEWPORT...FLORENCE...RAYMOND...LONG BEACH...
CATHLAMET
618 AM PST TUE DEC 29 2009
...INCREASING THREAT FOR COASTAL FLOODING LATE THIS WEEK...
INCREASINGLY HIGH ASTRONOMICAL TIDES COMBINED WITH A POTENT
PACIFIC STORM SYSTEM WILL BRING STRONG SOUTHERLY WINDS TO THE
COAST AND THE POTENTIAL FOR COASTAL FLOODING TOWARD THE END OF
THE WEEK. THE FIRST OF THESE STRONGER FRONTS IS EXPECTED TO MAKE
LANDFALL MIDDAY THURSDAY WHICH COINCIDES WITH ONE OF THE HIGHEST
HIGH TIDES OF THE YEAR.
A SECOND POWERFUL FRONT WILL SWING ON SHORE ON FRIDAY ALSO NEAR
THE TIME OF HIGH TIDE. LARGE WESTERLY SWELL GENERATED BY THE STORM
SYSTEM WILL ARRIVE AT THE COAST ON FRIDAY POSSIBLY GENERATING
HAZARDOUS SURF CONDITIONS AS WELL AS ADDING TO THE COASTAL
FLOODING POTENTIAL.
AT TOKE POINT NEAR WILLAPA BAY...ASTRONOMICAL HIGH TIDES OF 11.1
FT WILL OCCUR AT THE MIDDAY TIDES THURSDAY AND FRIDAY. WATER
LEVELS OVER 11 FT CREATE MINOR TIDAL OVERFLOWS WHILE 14.5 FT IS
THE THRESHOLD FOR MORE WIDESPREAD COASTAL FLOODING PROBLEMS. THE
MAGNITUDE OF TIDAL ANOMALY...THE ADDITIONAL BOOST TO THE COASTAL
WATER LEVEL DUE TO THE ACTION OF FRONTAL SYSTEM ITSELF...IS STILL
UNCERTAIN. HOWEVER IF THE STORM IS A STRONG ONE IT COULD ADD AN
ADDITIONAL 2 TO 4 FEET TO THE BASE ASTRONOMICAL TIDE.
FACTORS THAT WILL INFLUENCE THE FINAL WATER HEIGHT INCLUDE...THE
DEPTH OF THE LOW PRESSURE AREA AND STRENGTH OF THE WINDS...THE
AMOUNT OF RUNOFF ADDED TO THE COASTAL RIVERS AND THE AMOUNT WAVE
ACTION ALONG THE BEACHES TO DRIVE THE WATER FURTHER UP.