So, What's The State Of La Niña?

The Southern Oscillation Index (SOI) is WAY positive! Those are La Niña conditions for sure, and currently we seem to be pegged into a really strong La Niña state!


La Niña generally means above normal rain for eastern Australia, and that definitely seems to be the case at the moment. The major exception to a wet Australia, as ever, is southwestern Australia, particularly in and around the city of Perth, which seems locked, in a terrible way, into major, major drought, no matter what happens in eastern Australia.







So, what is the likely effect here in the good, ol' USA? According to the feds:

Likely La Niña impacts during October-December 2010 include suppressed convection over the central tropical Pacific Ocean, and enhanced convection over Indonesia. The transition into the Northern Hemisphere fall means that La Niña will begin to exert an increasing influence on the weather and climate of the United States. Expected U.S. impacts include an enhanced chance of above-average precipitation in the Pacific Northwest, and below-average precipitation across the southern tier of the country. Also, La Niña can contribute to increased Atlantic hurricane activity by decreasing the vertical wind shear over the Caribbean Sea and tropical Atlantic Ocean (see the August 5th update of the NOAA Atlantic Seasonal Hurricane Outlook). Conversely, La Niña is associated with suppressed hurricane activity across the central and eastern tropical North Pacific.

Given last week's storm across the Southwest, I'm a bit skeptical about all this. So what does the precipitation across the southern tier of states look like right now? The feds think it looks like it's drying out, or, to be more specific, that it's already dry across the South and that the dryness is creeping into the Southwest.

The NOGAPS model suggests next week will indeed by dry across the southern tier of states, with the exception of eastern Oklahoma and eastern Texas, where rain is likely, so maybe there is something to all this.