NCDC: U.S. Regional Drought Watch

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

National Climatic Data Center, 16 August 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

July was dry across much of the West and parts of the Southeast and Alaska. The Alaska dryness was apparent in both station precipitation reports and satellite-based wetness observations as well as monthly averaged streamflow, and was accompanied by unusually warm temperatures (station reports, satellite). The primary stations in Hawaii were drier than normal. In Puerto Rico, the pattern was mixed at the primary stations as well as the Cooperative stations for both the 4 weeks and 8 weeks ending on July 30.

Click here for map showing Palmer Z Index

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This month's short-term dryness compounded the long-term moisture deficits (last 9 to 24 to 36 to 60 to 72 months) in many areas. Dry conditions have persisted for much of the last 12 months across most of the West, Northwest, Southwest, and Southeast regions:

West - 31st driest July, 37th driest August-July, 3rd driest March-July
Northwest - 22nd driest July, 32nd driest August-July, 19th driest March-July
Southwest - 34th driest July, 39th driest August-July, 13th driest May-July
Southeast - 28th driest July, 35th driest August-July, 15th driest March-July

The West North Central region had a near normal July, but the last 12 months ranked as the 18th driest August-July, regionwide, in the 110-year record. For the Southeast region, even though mid-2002 to mid-2003 had record wet conditions, the unusual dryness before and after that period was so severe that the region shows up as dry at the 60-month (5-year) to 72-month (6-year) scale.

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-July (Arizona-10th)
- March-July (California-2nd, Wyoming-9th)
- February-July (Montana-9th)
- January-July (Montana-9th, Wyoming-10th, Maine-7th)
- December-July (Montana-10th, South Carolina-9th)
- October-July (Wyoming-9th)
- September-July (South Carolina-8th)
- August-July (Montana-8th, South Carolina-9th)
Soil moisture conditions:
- End-of-month soil moisture conditions were drier than normal in parts of the Southeast, Upper Midwest, Great Plains, and Alaska, and drier than normal across much of the West, based on model computations (CPC-1, CPC-2, MRCC).
- early August USDA topsoil moisture observations were dry to very dry (also compared to 5-year and 10-year climatologies) in states along the Gulf Coast, western Great Lakes, and Great Plains to Far West.
According to beginning-of-August USDA reports, more than 30 percent of the pasture and range land was in poor or very poor condition (higher than seasonal norms) in several western and northern Plains states. The percentage area increased, compared to 4 weeks ago, in the West, northern Plains, and western Great Lakes states.
Several large wildfires developed in east central Alaska during July, with a dozen major fires burning by July 23-25. Many of the Alaskan wildfires had subsided by the end of the month (wildfire loop), but several large fires had started by early August in the Pacific Northwest.
Much of the western U.S. has experienced dry conditions for the last five to six years. Continued dryness this month has exacerbated drought conditions across parts of the West.
- Reservoirs in the western states were still low or depleted.
- Streamflow levels were below seasonal norms across much of the West, both as computed by models and based on USGS observations. Below-normal monthly streamflows were also observed in parts of the Southeast, Alaska, and Hawaii.
- The percent area of the western U.S. (Rockies westward) experiencing moderate to extreme drought (as defined by the Palmer Drought Index) increased during July to about 80%. This is near 20th Century record historical levels, surpassed only by the droughts in 2002 and 1934.

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,
precipitation maps incorporating the effect of topography,
satellite-based observations of vegetative health,
satellite-based observations of surface moisture,
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
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 - Idaho - Kentucky - Maine - Maryland - Missouri-1 - Missouri-2 - Montana - New Jersey-1 - New Jersey-2 - New Jersey-3 - New Mexico - Oklahoma-1 - Oklahoma-2 - Oklahoma-3 - Oregon - Pennsylvania-1 - Pennsylvania-2 - South Carolina - Texas - Vermont - Virginia - 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 / July / U.S. Drought / Regional / Search / Help

http://www.ncdc.noaa.gov/oa/climate/research/2004/jul/drought-regional-overview.html
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Last Updated Wednesday, 20-Aug-2008 12:22:44 EDT by Richard.Heim@noaa.gov
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