Monday December 16, 2019, 2:44 PM
Tillamook County Emergency Management
HYDROLOGIC OUTLOOK – NATIONAL WEATHER SERVICE PORTLAND OR
…HEAVY RAIN LATER THIS WEEK COULD LEAD TO RIVER AND STREAM FLOODING FOR SOME PORTION OF SOUTHWEST WASHINGTON AND NORTHWEST OREGON…
A PROLONGED ATMOSPHERIC RIVER EVENT WILL BRING MODERATE TO HEAVY RAIN RATES BEGINNING WEDNESDAY NIGHT POTENTIALLY CONTINUING THROUGH SATURDAY. LIQUID EQUIVALENT PRECIPITATION AMOUNTS DURING THIS PERIOD COULD RANGE FROM 2″ TO 4″ FOR THE INTERIOR LOWLANDS WITH 3″ TO 8″ OR MORE ALONG THE COAST RANGE AND CASCADES. AT THIS TIME, THE NORTH OREGON COAST RANGE AND THE SOUTH WASHINGTON CASCADES APPEAR TO RECEIVE THE FOCUS OF PRECIPITATION. HOWEVER, THESE ATMOSPHERIC RIVER EVENTS ARE NOTORIOUSLY DIFFICULT TO PRECISELY PREDICT MORE THAN 24 TO 36 HOURS IN ADVANCE. FURTHER COMPLICATING THE ISSUE, CASCADE SNOW LEVELS WILL RISE FROM ABOUT 3500 FEET WEDNESDAY NIGHT TO ABOVE 6000 FEET BY FRIDAY EVENING.
AREAS THAT DO RECEIVE A PROLONGED PERIOD OF MODERATE AND HEAVY RAINFALL WILL LIKELY EXPERIENCE SIGNIFICANT RISES ON AREA RIVERS AND STREAMS. THE GREATEST CONCERN WILL BE ON RIVERS AND TRIBUTARIES THAT DO NOT HAVE FLOOD CONTROL RESERVOIRS.
THE NATIONAL WEATHER SERVICE WILL CONTINUE TO MONITOR THE RIVERS CLOSELY AND ISSUE WATCHES AND WARNINGS IF NEEDED. PEOPLE LIVING NEAR SOUTHWEST WASHINGTON AND NORTHWEST OREGON RIVERS SHOULD MONITOR THE LATEST WEATHER AND RIVER CONDITIONS FOR THE NEXT WEEK. LISTEN TO NOAA WEATHER RADIO OR CHECK HTTPS://WEATHER.GOV/PORTLAND
FOR FURTHER UPDATES.