Flood Watch This Weekend

December 19, 2014

This weekend is going to be a wet one and with lots of tweets and press releases are flying around.  I want to clear up some confusion about who may or may not see flooding.

HIGHLIGHTS

If you live in the lowlands AWAY FROM RIVERS (80% of us do), flooding is unlikely.  It appears there just won’t be that much rain in the lowlands.

If you live in the lowlands near a river that comes out of the Cascades or Coast Range…flooding is far more likely.  If you live along the Sandy, Clackamas, or Molalla rivers I think significant or major flooding is possible.

If you live in the foothills of the Coast Range/Cascades, western Gorge, or mountains themselves, be on the lookout for mud/landslides late Saturday through late Sunday.

Today’s social media world has made communicating clear weather information a bit tougher.  Of course I’m adding to it just by posting this…sorry!

I see two trends this afternoon:

1.  Precipitation is looking even lighter in the lowlands with very little Saturday evening through late Saturday night.

2.  We dry out in the lowlands by midday Sunday…probably dry Sunday afternoon north of Salem.

Take a look at our RPM forecast for rain in the Portland area…just an inch or so.  If this happens you can totally forget about flooding in the metro area.  Notice no rain after 8am Sunday as the main rain band slips south:

MarkRain_RPM_NEXT24HOURS

But take a look at Welches…same model:

MarkRain_RPM_NEXT24HOURS_Welches

continuous rain the whole period…that’s why those mountain rivers will be flooding by Sunday

Chief Meteorologist Mark Nelsen