Home » November 2012 Southwest Climate Outlook » Temperature Outlook
Forecasts
Published November 21, 2012

Temperature Outlook

 (December 2012–May 2013)
Data Source(s): NOAA-Climate Prediction Center (CPC)

The seasonal temperature outlooks issued by the NOAA-Climate Prediction Center (CPC) in November call for increased chances that temperatures will be similar to the warmest 10 years in the 1981–2010 period for the three-month seasons spanning December–May (Figures 9a–d). Recent warming trends during these periods influence the forecasts, as do agreement from a suite of dynamical models. The CPC is now more confident that a neutral El Niño-Southern Oscillation (ENSO) event will persist through the winter, which is a recent turn of events because in previous months indications favored the development of an El Niño event. ENSO-neutral conditions coupled with a negative Pacific Decadal Oscillation (PDO)—the current situation—often bring drier conditions to the Southwest. Since precipitation and temperatures are often positively correlated, drier conditions translate to warmer temperatures. The CPC also notes that the state and fate of the Arctic Oscillation (AO) remains a wildcard. If the AO is generally weak, cold Arctic air can 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.

Temperature Outlook
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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