The National Weather Service has included the North Olympic Peninsula in the following weather advisories:
…FLOOD WATCH NOW IN EFFECT THROUGH MONDAY AFTERNOON…
THE FLOOD WATCH IS NOW IN EFFECT FOR
* PORTIONS OF WESTERN WASHINGTON…INCLUDING THE FOLLOWING
COUNTIES… GRAYS HARBOR…CLALLAM…JEFFERSON…SKAGIT…
WHATCOM…KING…KITSAP…LEWIS…MASON…PIERCE…SNOHOMISH…
THURSTON.
* THROUGH MONDAY AFTERNOON
* ANOTHER WET WEATHER SYSTEM WILL BRING 3 TO 6 INCHES OF RAIN TO
THE CASCADES AND OLYMPIC MOUNTAINS LATER TODAY THROUGH SUNDAY…
WITH THE SNOW LEVEL 8000 TO 9000 FEET. RIVERS ARE ALREADY
RUNNING HIGH AND SOILS ARE SATURATED DUE TO HEAVY RAIN THAT HAS
FALLEN OVER THE AREA SINCE WEDNESDAY…WHICH WILL WORSEN THE
POTENTIAL FOR FLOODING.
* THERE IS A POTENTIAL FOR MINOR TO MODERATE FLOODING ON MOST MAIN
STEM RIVERS IN THE FLOOD WATCH AREA BEGINNING LATE TONIGHT OR
SUNDAY. NOTE THAT THE SKOKOMISH RIVER AND THE REACH OF THE
SNOQUALMIE RIVER NEAR CARNATION ARE ALREADY ABOVE FLOOD STAGE AS
A RESULT OF THE RAIN THAT FELL THURSDAY NIGHT AND FRIDAY.
* IN ADDITION MINOR FLOODING IS POSSIBLE ON THE REACH OF THE GREEN
RIVER THAT IS NOT PROTECTED BY LEVEES…IN THE RURAL AREA
UPSTREAM OF AUBURN TO HOWARD HANSON DAM. THAT WOULD BE SIMILAR
TO MINOR FLOODING THAT HAS OCCURRED THERE IN RECENT EVENTS.
FLOODING IS NOT EXPECTED ON THE LOWER PORTION OF THE GREEN RIVER
AFFECTING URBAN AREAS FROM AUBURN DOWNSTREAM.
PRECAUTIONARY/PREPAREDNESS ACTIONS…
FLOOD WARNINGS ARE IN EFFECT FOR PARTS OF THE WATCH AREA. THE
FLOOD WATCH MEANS THAT FLOODING IS POSSIBLE BUT NOT OCCURRING…
THIS APPLIES TO NEW AREAS OR LOCATIONS NOT ALREADY COVERED BY A
WARNING. MONITOR THE WEATHER AND BE READY TO ACT QUICKLY IF
FLOODING IS OBSERVED OR MORE WARNINGS ARE ISSUED.
LANDSLIDE WARNING
SAN JUAN COUNTY-WESTERN WHATCOM COUNTY-SOUTHWEST INTERIOR-
EAST PUGET SOUND LOWLANDS-WESTERN SKAGIT COUNTY-
EVERETT AND VICINITY-SEATTLE/BREMERTON AREA-TACOMA AREA-
ADMIRALTY INLET AREA-HOOD CANAL AREA-LOWER CHEHALIS VALLEY AREA-
OLYMPICS-EASTERN STRAIT OF JUAN DE FUCA-
WESTERN STRAIT OF JUAN DE FUCA-NORTH COAST-CENTRAL COAST-
WEST SLOPES NORTHERN CASCADES AND PASSES-
WEST SLOPES CENTRAL CASCADES AND PASSES-
1212 AM PST SAT JAN 15 2011
RAINFALL OF GENERALLY A HALF TO 1.5 INCHES DURING THE PAST 24
HOURS HAS MADE THE SOILS IN WESTERN WASHINGTON MORE SATURATED.
IN THE PAST THREE DAYS…1 TO 3 INCHES OF RAIN HAS FALLEN…WITH
AMOUNTS OF 4 TO 6 INCHES OBSERVED IN THE MOUNTAINS. ADDITIONAL
RAINFALL OF 1 TO 2.5 INCHES IS EXPECTED ON THE LOWLANDS BY LATE
SUNDAY…WITH AMOUNTS OF UP TO 6 INCHES ANTICIPATED IN THE
MOUNTAINS. THIS AMOUNT OF RAIN WILL PUT EXTRA PRESSURE ON SOIL
INSTABILITY…LEADING TO AN INCREASED RISK OF LANDSLIDES.
THE AMOUNT OF RAINFALL FORECAST IN 24 HOURS…ON TOP OF THE
CUMULATIVE RAINFALL OVER THE LAST THREE WEEKS…WILL PUSH WESTERN
WASHINGTON SOILS TO THE POINT WHERE THEY ARE MARGINALLY ABOVE THE
USGS LANDSLIDE INDEX. WHEN CUMULATIVE RAINFALL EXCEEDS THE USGS
LANDSLIDE CUMULATIVE THRESHOLD INDEX…RAINFALL INDUCED LANDSLIDES
ARE POSSIBLE DURING INTENSE RAINFALL OR WHEN RAINFALL AMOUNTS
EXCEED TWO INCHES IN 24 HOURS. A DIMINISHING RISK OF LANDSLIDES
WILL CONTINUE FOR SEVERAL DAYS AFTER THE RAIN ENDS.
WHILE THE USGS RAINFALL THRESHOLDS WERE DESIGNED FOR THE SEATTLE
AREA OF THE PUGET SOUND…MOST OF THE LOWLANDS OF WESTERN
WASHINGTON ARE SIMILARLY SUSCEPTIBLE TO LANDSLIDES CAUSED BY WET
SOILS. AREAS MOST SUSCEPTIBLE TO LANDSLIDES UNDER THESE CONDITIONS
ARE STEEP COASTAL BLUFFS AND OTHER STEEP HILLSIDES.
FOR MORE INFORMATION ABOUT CURRENT CONDITIONS…VISIT
WWW.WEATHER.GOV/SEATTLE …SELECT HYDROLOGY…AND THEN SCROLL DOWN
FOR THE LINK TO THE USGS LANDSLIDE INFORMATION PAGE.
