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INTERMOUNTAIN WEST CLIMATE SUMMARY, JANUARY 2008 Tem peratu re Outlook February - June 2008 Moderate La Nina conditions are expected to have a greater impact on temperature in February than previous months. The temperature outlook is largely based on trends and composites of climate impacts of La Nina from previous events of similar magnitude. The forecasts for February 2008 and subsequent seasons indi- cate an enhanced probability of above average over most of the U.S. including most of the Intermountain West (Figures 10a-c). For the northern tier of the U.S., including northern Wyoming, the forecast calls for equal chances (EC) of above-, near, and below average temperatures. In the southwestern U.S. including parts of southwestern Colorado and southeastern Utah, the odds of the upcoming seasons being in the warmest tercile (see notes below) rises to 50%, which indicates a greatly reduced chance (17 % instead of 33 %) of temperatures being in the coldest tercile. An updated temperature forecast for February 2008 will be released on January 31st on the CPC web page. Because of the shorter lead-time, the "zero-lead" forecast (i.e. on the last day of the previous month) often has increased skill over the half-month Figure 10a. Long-lead national temperature forecast for February 2008 (released January 17, 2008). Figure 10c. Long-lead national temperature forecast for Mar. - May 2008 (released January 17, 2008). lead forecasts. The next issue date for the seasonal Outlooks is February 21 st. Notes The seasonal temperature outlooks predict the likelihood (chance) of temperatures occurring in the above-average, near-average, and below-average categories. The numbers on the maps do not refer to actual temperature values, but to the probability in percent that temperatures will be in one of these three categories. The CPC outlooks are 3-category forecasts based on climate models in which the skill largely comes from the status of ENSO and recent trends. The categories are defined based on the 1971-2000 climate record; each 1- or 3-month period is divided into 3 categories (terciles), indicating the probabilities that the temperature in the period will fall into the upper third of the years (upper tercile, the middle third of the years (middle tercile, or around average), or the lowest third of the years (lower tercile). The forecast indicates the likelihood of the temperature being in the above-average (A, orange shading) or below-average (8) tercile--with a corresponding decrease in the opposite category. The near-average category is preserved at 33.30/0 likelihood, unless the anomaly forecast probability is very high. Equal Chances (EC) indicates areas for which the models do not have suffi- cient skill to predict the temperature with any confidence, representing equal chances or a 33.30/0 probability for each tercile. For a detailed description, see notes on the precipitation outlook page. A = Above . 60.0-69.90/0 . 50.0-59.90/0 . 40.0-49.90/0 Figure 10b. Long-lead national temperature forecast . 33.3-39.90/0 for Feb. - Apr. 2008 (released January 17, 2008). B = Below D 40.0-49.90/0 D 33.3-39.90/0 EC = Equal Chances On the Web · For more information and the most recent forecast images, visit: http://www.cpc.ncep.noaa.gov/products/predictions/90day/. Please note that this website has many graphics and may load slowly on your computer. · The CPC "discussion for non-technical users" is at: http://www.cpc.noaa.gov/products/predictions/90day/fxus05.html. · For IRI forecasts, visit: http://iri.columbia.edu/c1imate/forecast/net_asmt/. · More information about temperature distributions at specific stations in Colorado, Utah, Wyoming, and across the West can be found at the Western Regional Climate Center, http://www.wrcc.dri.edu/CLIMATEDATA.html. FORECASTS 11 3