Full Notification

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PORTLAND OR
337 PM PST THU DEC 18 2014

...FLOODING THREAT INCREASING SATURDAY NIGHT THROUGH MONDAY FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON RIVERS...

STRONG AND DEEP MOIST WESTERLY FLOW WILL BEGIN CROSSING THE PACNW COAST SATURDAY MORNING. A VERY LONG FETCH OF MOISTURE IS STRETCHING ACROSS THE PACIFIC WITH ORIGINS WEST TO THE SOUTH CHINA SEA AND HAS ABOVE AVERAGE POTENTIAL TO BRING HEAVY RAINS TO THE AREA. AS SUCH...THIS CONTINUES TO GIVE THE APPEARANCE OF A CLASSIC HIGH PRECIPITATION ATMOSPHERIC RIVER EVENT WHERE THE DEEP MOIST FLOW WILL SPEND A SIGNIFICANT AMOUNT OF TIME ON A NEARLY PERPENDICULAR COURSE AGAINST THE COAST RANGE WITH THE CASCADES TAKING A BIT HIGHER OF THE IMPACT. LATEST FORECASTS FOR FRIDAY NIGHT THROUGH MONDAY AFTERNOON BRING  8 TO 12 INCHES OF RAIN TO THE CASCADES AND FOOTHILLS...7 TO 11 INCHES FOR THE COAST RANGE...5 TO 7 INCHES ALONG THE IMMEDIATE COAST...AND 3 TO 4 INCHES ALONG THE I-5 CORRIDOR.

GIVEN LATEST DATA...IT APPEARS MULTIPLE COAST RANGE RIVERS HAVE A MODERATE POTENTIAL OF EXCEEDING FLOOD STAGE. ADDITIONALLY...THIS EVENT HAS SUFFICIENT DEPTH TO BRING SIGNIFICANT RAINS TO THE NORTH OREGON AND SOUTH WASHINGTON CASCADES WHERE RIVERS WILL ALSO SEE POTENTIAL FOR NOTABLE FLOODING.

KEEP IN MIND THAT DETAILS WILL ALWAYS BE IN FLUX UNDER THESE
SCENARIOS AS SUBTLE NORTH OR SOUTH SHIFTS COLD MAKE DRAMATIC DIFFERENCES IN WHICH BASINS RECEIVE EXTENDED PERIODS OF MODERATE TO HEAVY RAIN. PLEASE CONTINUE TO FOLLOW THE LATEST FORECASTS AND IMPACTS AS CONDITIONS WARRANT.

STAY UP TO DATE WITH THE LATEST NWS FORECASTS AT
WEATHER.GOV/PORTLAND OR MOBILE.WEATHER.GOV

RIVER FORECASTS ARE AVAILABLE ON OUR WEB PAGE AT
HTTP://WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=PQR (ALL LOWER CASE)