Despite recent rains, the 2014 water year ended this week with a sizable precipitation deficit in Clark County.
Vancouver finished the water year — Oct. 1 through Sept. 30 — about 10 inches below normal, a gap driven by an unusually dry fall and early winter last year. December alone was a whopping 5.25 inches below normal in the rainfall department, according to the National Weather Service.
Vancouver typically records about 40 inches of rainfall per year, according to the weather service.
A possible El Nino brewing in the Pacific Ocean could bring continued dry conditions to Southwest Washington this winter. But the weather phenomenon has so far only teased scientists.
“It doesn’t seem to want to start,” said Richard Heim, a meteorologist with the National Climatic Data Center in North Carolina. “It’s just not behaving like we would expect an El Nino to behave.”
The pattern often means a warmer and drier winter in the Northwest. La Nina winters, by contrast, tend to be cooler and wetter. But neither is a guarantee.
Forecasters watch several factors, including ocean temperatures, to determine what long-term weather patterns may develop. Some data point to an El Nino this year, but not all of the usual indicators have followed suit, Heim said.
The National Oceanic and Atmospheric Administration last month pegged the chance of an El Nino at 60 to 65 percent, down from 80 percent earlier this year. If the pattern does develop in the coming weeks, most models indicate it will be a weak El Nino, according to the agency.
In its most recent update, the Climate Prediction Center kept its “El Nino Watch” in place. That means conditions are favorable, but the pattern has not yet materialized.
‘Abnormally dry’
Less rain this winter could worsen already parched conditions across much of the Northwest, including Southwest Washington. Most of Clark County is currently considered “abnormally dry” by the U.S. Drought Monitor. But it’s not dry enough to reach one of the four categories of drought: moderate, severe, extreme and exceptional. (In California, for example, exceptional drought still grips almost 60 percent of the state, according to the agency.)
The “abnormally dry” classification for Clark County could creep into drought territory depending on what the coming weeks and months bring, Heim said. Or tt could go back to normal.
Fall and winter rains are a huge driver of mountain snowpack in the Northwest, which has far-reaching implications for the region’s water supply. Last year’s snowpack started alarmingly low before making a notable comeback by the end of the spring.
The 2015 water year will begin on a dry note in Clark County, according to the weather service. Forecasters don’t expect any rain for the next several days, and temperatures could climb back into the mid 70s by this weekend.
