While both the PDSI and PHDI indices show long-term moisture conditions, the PDSI depicts meteorological drought while the PHDI depicts hydrological drought. The Palmer Z Index depicts moisture conditions for the current month, while the Palmer Hydrological Drought Index (PHDI) and Palmer Drought Severity Index (PDSI) depict the current month's cumulative moisture conditions integrated over the last several months. The Palmer drought indices measure the balance between moisture demand (evapotranspiration driven by temperature) and moisture supply (precipitation). Percent area of the CONUS in moderate to exceptional drought, Januto present, based on the U.S. (20.6 percent of the CONUS).Īccording to the Palmer Drought Index, which goes back to the beginning of the 20 th century, about 13.3 percent of the CONUS was in moderate to extreme drought at the end of November, a decrease of about 3.7 percent compared to last month. When integrated across the CONUS, November 2015 ranked as the fourth wettest November in the 1895-2015 record, with the national drought footprint shrinking to 17.2 percent of the U.S. Pacific systems brought above-normal precipitation to much of Alaska and Hawaii, while Puerto Rico had a mixed precipitation anomaly pattern. These systems then tapped Gulf of Mexico moisture and, in some cases, tropical Pacific moisture from the remnants of Hurricane Sandra to produce heavy precipitation across the Great Plains to Midwest and Southeast.ĭrier-than-normal weather dominated the Northeast to parts of the Ohio Valley, and parts of the Northern Plains and West.
Pacific moisture with these systems brought above-normal precipitation to parts of the West.
The weather and climate of November 2015 were influenced by a strong El Niño and a vigorous upper-level circulation, which directed numerous weather systems across the CONUS, some of which were enhanced by tropical moisture.Ī steady stream of Pacific weather systems brought drought-ending rain to coastal Washington.Ī series of deep troughs and cutoff lows moved in the jet stream flow across the southern half of the country. Drought Monitor drought map valid December 1, 2015. including Alaska, Hawaii, and Puerto Rico) was classified as experiencing moderate to exceptional (D1-D4) drought at the end of November. Drought Monitor, about 20.6 percent of the contiguous U.S. These filenames begin with "climdiv".Īccording to the weekly U.S. are available at the Climate Division: Temperature-Precipitation-Drought Data page. Historical temperature, precipitation, and Palmer drought data from 1895 to present for climate divisions, states, and regions in the contiguous U.S. On a broad scale, the 1980s and 1990s were characterized by unusual wetness with short periods of extensive droughts, the 1930s and 1950s were characterized by prolonged periods of extensive droughts with little wetness, and the first decade of the 2000s saw extensive drought and extensive wetnessĪ file containing the national monthly percent area severely dry and wet from 1900 to present is available for the severe to extreme and moderate to extreme categories. fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of November. fell in the severely to extremely wet categories.Ībout 13 percent of the contiguous U.S.
They will change when the final data are processed, but will not be replaced on these pages.īased on the Palmer Drought Index, severe to extreme drought affected about 9 percent of the contiguous United States as of the end of November 2015,Ī decrease of about 2 percent from last month.Ībout 21 percent of the contiguous U.S. Please note that the values presented in this report are based on preliminary data. State/Regional/National Moisture Status.CONUS Agricultural & Hydrological Impacts.Standardized Precipitation Evaportranspiration Index.
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