WARM APRIL FOR U.S., DROUGHT REMAINS IN WEST
AS SNOWPACK MELTS RAPIDLY
All regions of the contiguous United States were near average to warmer than average in April 2004, according to scientists at the National Oceanic and Atmospheric Administration's (NOAA) National Climatic Data Center (NCDC) in Asheville, N.C. The Southeast and North Central regions were unusually dry, but precipitation was above average in Texas and the Southwest. The global average temperature was 3rd warmest on record for the month of April.
NOAA scientists report that the average temperature for the contiguous United States in April (based on preliminary data) was 53.6°F (12.0°C), which was 1.5°F (0.8°C) above the 1895-2003 mean, the twenty-fourth warmest April on record. Florida was the only state in the contiguous United States with a below average statewide temperature. The mean temperature in four western states was much above average. An additional 28 states were warmer than average. Alaska was also warmer than average with a statewide temperature of 4.1°F (2.3°C) above the 1971-2000 mean, the 7th warmest April since reliable records began in 1918. Record heat occurred in much of the coastal West in the last week of April and first few days of May, with temperatures soaring to over 10°F above average in parts of California, Oregon and Washington.
Precipitation for the contiguous United States as a whole was near average, with much of the a North Central regions, Southeast and parts of the West drier than normal while wetter than average conditions occurred in six states in the Southwest and Northeast. During the first week of the month, a large, slow-moving storm system produced one to five inches of rain across much of New Mexico and adjacent Mexico. This rainfall resulted in a deadly flash flood in Coahuila State, Mexico, killing 36 people.
Snowpack was much below average in most of the western U.S. at the beginning of May, partially as a result of a large ridge of high pressure causing record heat and accelerating snowmelt. Reservoir levels also remained below average in many areas of the West, and at the end of the month 61% of the western United States was in moderate to extreme drought, based on a widely used measure of drought, the Palmer Drought Index. The most extensive drought on record for the West occurred in July 1934, when 97% of the region was in moderate to extreme drought.
The average global surface temperature for combined land and ocean surfaces during April 2004 (based on preliminary data) was 0.94°F (0.52°C) above the 1880-2003 long-term mean. This was the 3rd warmest April since 1880 (the beginning of reliable instrumental records), following a record warm April in 1998 and the second warmest April in 2002. Land surface temperatures were anomalously warm throughout many parts of the world, and temperatures in much of the central and eastern equatorial Pacific were near average as the neutral phase of ENSO (El Nino/Southern Oscillation) continued. The global ocean surface temperature was 3rd warmest on record for April.