Oregon may be on path to a big flood, experts say

[senorpepr]

PORTLAND — In 1964, in what state climatologists say was the worst flood recorded in the Pacific Northwest, this city became an island.

Miles of railroads disappeared under watery sheets. Bridges became submerged. Forty-seven people died in four states.

Experts say the storm lashing much of the region this week has two of the three tell-tale signs that preceded the 1964 deluge.

"To get a big flood, it's like baking a cake," said George Taylor, the state climatologist. "There's a recipe, and it has three ingredients. Two of them have already been met," he said.

First, a wet autumn fills the rivers and saturates the soil. Then, the snow starts to fall.

The snowpack becomes a ready source of water, if an atmospheric event should cause it to melt. Both the wetness and the depth of snow this winter in Oregon mirror the measurements taken in the weeks before the 1964 "Christmas Flood."

But it's the third ingredient, the so-called "Pineapple Express," that will make or break the flood prediction.

The Pineapple Express is a moniker given to the warm, tropical rains that come in a straight line from the Hawaiian Islands, home to lush pineapple groves. The subtropical jet stream is a relatively common weather pattern — washing the Oregon and Washington coasts several times a year, Taylor said.

It presents a flooding danger when it is preceded by the two other ingredients, he said.

"One and two already happened. We may experience three," Taylor said. "If you look at satellite pictures you see a big sucker, like a left hook about to hit us in the chin. Unfortunately, it's difficult to know in advance how much rain will come out of these kinds of systems," he said.

Taylor said he's hoping that it won't bring as much rain as 1964.

[FLguy]

excellent post...

however with the SOI negative and the MJO related enhanced convection enhanced convection east of 120E...i think the best potential for heavy precip is further south along the west coast (say central and southern CA)

if the enhanced convection was near 120E and supressed convection was east of the dateline i could see the set-upfor the pineapple express. right now i dont see that happening per the state of the MJO. once we see the wave get re-established near 120E.