NCDC: U.S. Regional Drought Watch

NCDC / Climate Mon. / Climate-2004 / May / U.S. Drought / Regional / Search / Help

Climate of 2004 - May
U.S. Regional Drought Watch

National Climatic Data Center, 15 June 2004

Global Analysis / Global Hazards / United States / U.S. Drought / National Drought Overview / Extremes
Use these links to access detailed analyses of Global and U.S. data.

Regional Drought Overview / Additional Contacts / Questions

Regional Overview

May was warmer than normal and dry across the Southeast, southern and central Plains, and parts of the West. Above-normal rainfall brought improving conditions to the Upper Midwest (April vs. May) and short-term relief to the drought areas of the Pacific Northwest. Much of Alaska was wetter than normal, but drier than normal conditions prevailed at the primary stations along the southern coastal band and southeastern panhandle. The rainfall pattern in Hawaii was mixed. The primary stations in Puerto Rico were generally wetter than normal, but a few stations at the western end of the island were drier than normal for the 4 weeks to 8 weeks ending in May.

Click here for map showing Palmer Z Index

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Dry conditions have persisted during most of the last 8 months across much of the Southeast, giving the region the seventh driest spring (March-May) and ninth driest January-May in the 110-year record. This sharply contrasts with the previous 13 months which were predominantly wet, and marks a return to the dry conditions which prevailed for much of the preceding four years. The recent dryness resulted in the third driest May for the Southwest region and sixth driest spring (March-May) for the West region.

This month's short-term dryness compounded the long-term moisture deficits (last 9 to 24 to 36 to 60 months) in many areas. The West North Central region had the 11th driest June-May on record this year, marking the fifth consecutive such 12-month period with below-normal precipitation.

Click here for map showing Current Month Palmer Hydrological Drought Index

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Some regional highlights:

Several states had the tenth driest, or drier, month or season for:
- May (Arizona-2nd, Oklahoma-2nd, Colorado-4th, New Mexico-8th, Florida-8th)
- spring (March-May) (Georgia-2nd, Florida-4th, South Carolina-4th, California-5th)
- January-May (Maine-6th, North Carolina-8th, South Carolina-9th)
- December-May (Georgia-5th, South Carolina-10th)
- November-May (South Carolina-8th)
- August-May (South Carolina-7th)
- July-May (Wyoming-9th)
- June-May (Montana-7th)
Soil moisture conditions:
- End-of-month soil moisture conditions were much drier than normal in the Southeast and parts of the Great Plains and West, based on model computations.
- USDA topsoil moisture observations were dry to very dry (both observed and compared to recent [5-year and 10-year] climatologies) in states in the Southeast, Great Plains, and Rocky Mountains.
According to end-of-May USDA reports, more than 30 percent of the pasture and range land was in poor or very poor condition in the Rocky Mountain states and adjoining central and northern Plains states, and in California, Florida, and Georgia. Several other states had poor or very poor condition percentages that were higher than seasonal norms.
Much of the western U.S. has experienced dry conditions for the last five years. Continued dryness this month has exacerbated drought conditions across parts of the West.
- High elevation SNOTEL station reports reveal a much below-average mountain snowpack. Western streams and reservoirs depend on water from spring snowmelt, but the snowpack has been less extensive and melting earlier than normal in recent years.
- Reservoirs in most of the western states were still low or depleted.
- Streamflow levels were below seasonal norms, especially in the northern Rockies, both as computed by models and based on USGS observations.
- The percent area of the western U.S. (Rockies westward) experiencing moderate to extreme drought (as defined by the Palmer Drought Index) increased during May to about 67%. While this is not near record historical levels, it is still comparable to the major droughts of the 20th Century.

These overall conditions are evident in the following indicators:

Palmer Drought Indices,
Standardized Precipitation Index,
airport station percent of normal precipitation maps,
statewide precipitation rank maps,
Cooperative station percent of normal precipitation maps,
satellite-based observations of vegetative health,
National Weather Service model calculations of
Midwest Regional Climate Center model calculations of soil moisture,
percent of average maps for the SNOTEL stations in the western mountains provided by the Western Regional Climate Center
- hydrologic year precipitation,
- snow water equivalent of snowpack,
streamflow maps maintained by the USGS.

A detailed review of drought conditions is available for the following regions and states:

Click here for map showing the nine U.S. standard regions

Additional Contacts:

Damage due to the drought has been summarized by NOAA and the Office of Global Programs in the Climatological Impacts section of the Climate Information Project. Crop impact information can be found at the USDA NASS (National Agricultural Statistics Service) and Weekly Weather and Crop Bulletin pages. Drought statements by local National Weather Service Offices can be found at the NWS Hydrologic Information Center. Drought threat assessments and other information can be found at NOAA's Drought Information Center. Additional drought information can be found at the National Drought Mitigation Center, the USDA's National Agricultural Library, the interim National Drought Council, and the NOAA Paleoclimatology Program. The following states have set up web pages detailing current drought conditions and/or their plans to handle drought emergencies:

Colorado - Delaware - Delaware River Basin (DE-NJ-NY-PA) - Florida Panhandle - Georgia - Hawaii - Idaho - Kentucky - Maine - Maryland - Missouri-1 - Missouri-2 - Montana-1 - Montana-2 - Nebraska - New Jersey-1 - New Jersey-2 - New Jersey-3 - New Mexico - North Carolina - Oklahoma-1 - Oklahoma-2 - Oklahoma-3 - Oregon - Pennsylvania-1 - Pennsylvania-2 - Pennsylvania-3 - South Carolina - Texas - Vermont - Virginia - Washington - Wyoming

For additional information on current and past wildfire seasons please see the National Interagency Fire Center web site or the U.S. Forest Service Fire and Aviation web site.

NCDC's Drought Recovery Page shows the precipitation required to end or ameliorate droughts and the probability of receiving the required precipitation.

Additional climate monitoring graphics can be found at the Climate Prediction Center's monitoring pages:

Precipitation and modeled soil moisture anomaly maps for the Midwest U.S. can be found at the Midwest Regional Climate Center's monitoring page.

Drought conditions on the Canadian prairies can be found at the Agriculture and Agri-Food Canada Drought Watch page.

For all climate questions other than questions concerning this report, please contact the National Climatic Data Center's Climate Services Division:

Climate Services Division
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4876
phone: 828-271-4800
email: ncdc.info@noaa.gov

For further information on the historical climate perspective presented in this report, contact:

Richard Heim
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
email: Richard.Heim@noaa.gov

NCDC / Climate Mon. / Climate-2004 / May / U.S. Drought / Regional / Search / Help

http://lwf.ncdc.noaa.gov/oa/climate/research/2004/may/drought-regional-overview.html
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Last Updated Tuesday, 29-Nov-2005 14:05:07 EST by Richard.Heim@noaa.gov
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