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Here is a report from NOAA on the latest ENSO trends for this fall and winter:

Over the last 30 days sea surface temperatures in the equatorial pacific have been warming up and other indicators such as sub-surface ocean temperatures and a gradual reversal in the equatorial wind and pressure fields reflect a likely progression towards El Nino.

Across the eastern equatorial Pacific ocean sea surface temperatures continue to warm, with the greatest warming occurring adjacent to the west coasts of Central and South America where SSTs have risen in excess of 1.5 degrees Celsius above the average as of the middle of July.

Farther west within the region of the eastern Pacific known as Nino 3.4, SSts anomalies varied from .3 degrees C on its west side to 1.4 degrees C at its eastern border.

Since early February of 2012, sea surface temperatures (SSTs) for region Nino 3.4 has exhibited a positive or upward trend.
15 out of a total of the 18 dynamic models predict at least a weak El Nino by August, September, October of 2012 and possibly a moderate El Nino by September, October, November of 2012.

The latest plume-based probabilistic ENSO forecast indicates virtually no chance of a La Nina for the remainder of 2012.

The model forecast does indicate a high probability of an El Nino this fall and winter.

77% chance of an El Nino in September, October, November

81% chance of an El Nino in October, November, December

78% chance of an El Nino November, December, January

69% chance of an El Nino December, January, February

The model also predicts a return to neutral ENSO conditions by the spring of 2013.

If a weak to moderate El Nino develops in the equatorial pacific ocean Montana could be looking at a warmer and drier than winter season December through February. If a below normal snowpack winter does come our way the current drought situation will be prolonged throughout southern Montana into the first half of 2013.

Typically, when El Nino's weaken in the spring months a very wet pattern develops.