Home » October 2012 Southwest Climate Outlook » Temperature Outlook
Forecasts
Published October 24, 2012

Temperature Outlook

 (November 2012–April 2013)
Data Source(s): NOAA-Climate Prediction Center (CPC)

The seasonal temperature outlooks issued by the NOAA-Climate Prediction Center (CPC) in October call for slightly increased chances that temperatures will be similar to the warmest 10 years in the 1981–2010 period for the three-month seasons spanning November–April (Figures 8a–d). Recent warming trends during these periods influence the forecasts, as do a suite of dynamical models. The CPC notes that a few wildcards remain in the deck that could influence temperatures in coming months. First, the fate of ENSO remains in doubt. While many forecast models were predicting an El Niño a few months ago, the chances for an event have been declining and the expectation is that even if one forms, it will be weak and short-lived. El Niño events often bring the Southwest wetter conditions, which, in turn, can cause generally cooler weather. The other uncertainty will be in the general character of the Arctic Oscillation (AO). A weak AO can allow cold Arctic air to spill south, and when entrained in storm tracks, can deliver very cold weather to the Southwest. The AO, however, is hard to forecast more than two weeks in advance.

Seasonal Temperature Forcasts for the U.S.
Notes:

These outlooks predict the likelihood (chance) of above-average, average, and below-average temperature, but not the magnitude of such variation. The numbers on the maps do not refer to degrees of temperature.

The NOAA-CPC outlooks are a 3-category forecast. As a starting point, the 1981–2010 climate record is divided into 3 categories, each with a 33.3 percent chance of occurring (i.e., equal chances, EC). The forecast indicates the likelihood of one of the extremes—above-average (A) or below-average (B)—with a corresponding adjustment to the other extreme category; the “average” category is preserved at 33.3 likelihood, unless the forecast is very strong.

Thus, using the NOAA-CPC temperature outlook, areas with light brown shading display a 33.3–39.9 percent chance of above-average, a 33.3 percent chance of average, and a 26.7–33.3 percent chance of below-average temperature. A shade darker brown indicates a 40.0–50.0 percent chance of above-average, a 33.3 percent chance of average, and a 16.7–26.6 percent chance of below-average temperature, and so on.

Equal Chances (EC) indicates areas where no forecast skill has been demonstrated or there is no clear climate signal; areas labeled EC suggest an equal likelihood of above-average, average, and below-average conditions, as a “default option” when forecast skill is poor.

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