STATE OF THE CLIMATE IN 2009

tornadoes (rated EF3–EF5) reported in 2009 was 21,which is also below average.There were 21 tornado fatalities in 2009, associatedwith nine tornadoes, which is the second lowest in the1950–2009 record. The most deadly tornado of theyear occurred in Oklahoma on 10 February, whenan EF4 killed eight people. This was the state’s firstFebruary EF4, and the deadliest February tornado inOklahoma history. February was also the most deadlymonth of the year with a total of nine fatalities.Louisiana and Alabama had their busiest tornadoyear of the decade, while the typically active states ofTexas and Kansas had their second slowest. The largestoutbreak of the year occurred on 9–10 April when117 tornadoes were reported from Texas to NorthCarolina. A total of five tornado-related deaths werereported—three in Arkansas and two in Tennessee.There were also 221 straight-line damaging wind reportsand 435 severe hail reports associated with theoutbreak. According to preliminary data, Novembertied as the second quietest November since 1950 withonly two tornado reports. In the past, November hasbeen a fairly active month for tornadoes in the southeasternUnited States.rainy season, at the end of August and beginning ofSeptember temperatures quickly decreased to normalin most of these regions, with the exception of theYucatan Peninsula and the southeastern regions,where anomalies between 1.0°C and 2.0°C abovenormal remained.By the end of November and during December,unusually low temperatures prevailed in the northwestern,northern, western, and central regions ofMéxico; in the states of the northern Gulf coast; andin the Sierra Madre Oriental and the Eje Neovolcanicoregions. The anomalies were as much as 4.0°C belownormal. This behavior was related to intense humidityfrom the tropical Pacific and its interaction with coldfronts; these conditions resulted in cloudier-thannormalskies, which led to low diurnal temperaturesin most of the country.(ii) PrecipitationThe rain pattern was variable during the year andacross the country, but was generally very dry (Fig.7.6b). The year began much drier than normal in thewinter and spring, but it changed to normal precipitationin the beginning of the rainy season (May–June).3) México—V. Davydova-Belitskaya and F. Romero-CruzMéxico experienced warmer-than-normal temperaturesin 2009 and on average it was 10% drierthan normal. México’s National Meteorological Service(SMN) reported a national precipitation averageof 681.9 mm, compared with a historical average of759.6 mm (1971–2000). The nationwide annual meantemperature was 22.5°C, which was 1.0°C above thelong-term climate average. Extreme weather causedseveral deaths and millions of dollars in damages tothe agricultural and water sectors.(i) TemperatureIn general, México registered an annual temperatureanomaly in a range from -1.0°C to +1.0°C, whichis considered a normal variation. With the exceptionof the Baja California Peninsula, northwestern, northern,northeastern, and western regions, as well as theYucatan Peninsula, the anomalies were between 1.0°Cand 2.0°C above normal (Fig. 7.6a). Annual mean temperaturefor the country as a whole was 22.5°C, withan anomaly of 1.0°C above normal. However, spatialand temporal variations were observed. During thewinter, spring, and summer, anomalies from +1.0°Cto +4.0°C were found in the northern, northwestern,western, and central regions of the country as wellas in the Yucatan Peninsula. Recovering from theFig. 7.6. (a) Annual mean temperature anomalies (°C)for Mexico (based on 1971–2000) for 2009 and (b) annualtotal precipitation anomalies (% of 1971–2000)for 2009. (Source: National Meteorological Serviceof México.)S142 | juNE 2010