Heavy Rain Starts Saturday Night

By Rod Hill on 2011-01-15

FLOODING POSSIBLE SATURDAY NIGHT THROUGH MONDAY ALONG RIVERS
IN SOUTHWEST WASHINGTON AND NORTHWEST OREGON.

.PERIODS OF HEAVY RAIN WEDNESDAY THROUGH FRIDAY THIS WEEK MELTED
A FAIR AMOUNT OF LOW ELEVATION SNOW AND ICE FROM EARLIER IN THE
WEEK AND PRIMED RIVERS ACROSS MUCH OF SOUTHWEST WASHINGTON AND
NORTHWEST OREGON. ANOTHER PERIOD OF WARM HEAVY RAIN WILL SPREAD
IN OVER THE AREA THIS WEEKEND...AND MAY PUSH SEVERAL RIVERS TO OR
ABOVE FLOOD STAGE SUNDAY AND MONDAY. A WEAKER SYSTEM WILL MOVE
THROUGH ON SATURDAY...THEN THE WARM FRONT FROM THE NEXT STRONGER
SYSTEM WILL BRING THE FIRST SURGE OF HEAVY RAIN TO THE AREA
SATURDAY NIGHT. THE ASSOCIATED COLD WILL MOVE ACROSS THE AREA
SUNDAY FOR MORE HEAVY RAIN. THE RIVERS MOST AT RISK ARE THOSE
DRAINING THE COASTAL MOUNTAINS IN SOUTHWEST WASHINGTON AND
NORTHWEST OREGON...RIVERS DRAINING THE SOUTH WASHINGTON
CASCADES...AND WILLAMETTE RIVER TRIBUTARIES DRAINING THE COAST
RANGE AND THE NORTH CASCADES.

* A SUSTAINED PERIOD OF HEAVY RAIN IS EXPECTED TO DEVELOP
 SATURDAY NIGHT AND CONTINUE THROUGH MOST OF SUNDAY. SNOW
 LEVELS WILL BE AROUND 8000 FEET OR HIGHER THROUGHOUT THIS
 HEAVY RAINFALL EVENT. STORM TOTAL RAINFALL AMOUNTS OF 4 TO 6
 INCHES ARE EXPECTED ALONG THE COAST AND IN THE COASTAL
 MOUNTAINS...WITH 1 TO 3 INCHES IN THE VALLEYS.

* RIVERS OF GREATEST CONCERN TO REACH FLOOD STAGE INCLUDE THE
  GRAYS RIVER IN WAHKIAKUM COUNTY...THE COWLITZ RIVER IN COWLITZ
  COUNTY...THE NEHALEM RIVER IN COLUMBIA AND CLATSOP COUNTIES...
  THE WILSON AND TRASK RIVERS IN TILLAMOOK COUNTY...THE SILETZ
  RIVER IN LINCOLN COUNTY...THE CLACKAMAS RIVER IN CLACKAMAS
  COUNTY...JOHNSON CREEK IN MULTNOMAH COUNTY...THE UPPER TUALATIN
  RIVER IN WASHINGTON COUNTY...THE PUDDING RIVER IN CLACKAMAS AND
  MARION COUNTIES...THE MARYS RIVER IN BENTON COUNTY...THE
  LUCKIAMUTE RIVER IN POLK AND BENTON COUNTIES...AND THE SANTIAM
  RIVER IN LINN AND MARION COUNTIES. THE HEAVY RAIN MAY ALSO CAUSE
  SMALLER CREEKS AND STREAMS TO FLOOD...AS WELL AS CAUSE AREAS OF
  FLOODING IN OTHER RURAL AND URBAN AREAS.


**The combination of heavy rains, already swollen rivers and very high snow levels
     make this a potentially dangerous event.