OYLE, Okla. — In most years, the dark clouds over western Oklahoma in the spring would be bringing rain. This year, they're more likely to be smoke from wildfires that have burned thousands of acres in the past month as the state and its farmers struggle with a severe drought.
Oklahoma was drier in the four months following Thanksgiving than it has been in any similar period since 1921. That's saying a lot in the state known for the 1930s Dust Bowl, when drought and high winds generated severe dust storms that stripped the land of its topsoil.
Neighboring states are in similar shape as the drought stretches from the Louisiana Gulf coast to Colorado, and conditions are getting worse, according to the U.S. Drought Monitor. The area in Texas covered by an extreme drought has tripled in the past month to 40 percent, and in Oklahoma it nearly doubled in one week to 16 percent, according to the monitor's March 29 update.
An extreme drought is declared when there's major damage to crops or pasture and widespread water shortages or restrictions.
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http://www.tulsaworld.com/news/article.aspx?subjectid=14&articleid=20110406_12_0_COYLEO62268&rss_lnk=12Drought Monitor:
National Drought Summary -- March 29, 2011
The discussion in the Looking Ahead section is simply a description of what the official national guidance from the National Weather Service (NWS) National Centers for Environmental Prediction is depicting for current areas of dryness and drought. The NWS forecast products utilized include the HPC 5-day QPF and 5-day Mean Temperature progs, the 6-10 Day Outlooks of Temperature and Precipitation Probability, and the 8-14 Day Outlooks of Temperature and Precipitation Probability, valid as of late Wednesday afternoon of the USDM release week. The NWS forecast web page used for this section is:
http://www.cpc.ncep.noaa.gov/products/forecasts/.Overview: Heavy rain eased drought across portions of the Southeast, while drought intensified across much of the south-central and southwestern U.S.
Midwest: Dry, cool weather prevailed over northern Indiana, where long-term precipitation deficits persist (4-6 inches below normal over the past 180 days). In the northern Great Lakes, Moderate Drought (D1) was introduced to northern-most portions of Michigan to account for below-normal snowfall and corresponding low 3- and 6-month Standardized Precipitation Indices.
The Mid-Atlantic: The recent wet, cool trend continued, although rainfall totals were mostly less than 1 inch. Lingering Abnormally Dry and Moderate Drought regions of the lower Delmarva and southern Virginia reported mostly less than 0.25 inch, which was not sufficient to further improve drought designation. Streamflows in the southern portions of the region continued to reflect D0 and D1 status.
Southeast: Locally heavy rain (2-4 inches) swept eastward from southern Tennessee and northern Alabama into Georgia and South Carolina, affording northern portions of the region relief from Moderate Drought (D1) and Abnormal Dryness (D0). Precipitation was somewhat lighter (less than 1.5 inches) in North Carolina’s core Severe Drought (D2) area; with weekly normal precipitation over an inch, the rainfall was not enough to warrant drought reduction in this area. Moderate to heavy rain (2-4 inches, locally more) in central Florida also provided relief from Moderate to Severe Drought (D1 and D2), although the rain largely bypassed the southern Extreme Drought (D3) region. Consequently, modest drought improvement was noted in central Florida, while southern and eastern Florida remained largely unchanged. In northern Florida, D1 was expanded in eastern portions of the Panhandle, where precipitation deficits over the past 60 days have tallied 4 to 6 inches (less than 50 percent of normal). In southern Georgia, a small band of heavy showers (2-3 inches) led to a minor adjustment to Severe Drought (D2), while Severe and Extreme Drought were expanded westward over southern portions of the state to reflect declining soil moisture and streamflow percentiles.
Delta: Dry, warmer-than-normal weather (up to 9°F above normal) in southern portions of the region contrasted with periods of rain and below-normal temperatures farther north. Changes in drought across southern Louisiana were minor, with a slight eastward expansion of Severe Drought (D2) to reflect soil moisture rankings in the lowest 5th percentile and Standardized Precipitation Indices indicative of D2 conditions or worse. Farther north, upwards of 5 inches of rain in northeastern Mississippi led to 1-category improvements of the current drought depiction, while lesser totals (1-3 inches) resulted in minor improvements in D0 (Abnormal Dryness) across southern Missouri. It should be noted that the core D3 (Extreme Drought) regions of the Delta continue to wrestle with deficits locally in excess of 12 inches over the past 90 days and 15 to 20 inches (locally more) over the past 180 days (less than 50 percent of normal over both timescales).
Texas & Oklahoma: Dry, hot conditions led to widespread intensification and expansion of drought across Texas, where daytime highs routinely reached into the upper 80s and lower to middle 90s. In Oklahoma, despite somewhat cooler weather, conditions likewise deteriorated under sunny skies. By week’s end, soil moisture percentile rankings depicted D3 (Extreme Drought) or worse from southeastern Oklahoma into most of central and eastern Texas. In addition, 6-, 9- and 12-month Standardized Precipitation Indices (SPI) likewise reflected D3 or D4 conditions over much of this same region. Remote sensing data (in particular, the Vegetation Health Index) depicted widespread vegetation stress across southern Oklahoma and much of Texas. Meanwhile, from South Texas into the Edwards Plateau and Trans-Pecos regions, 3- and 6-month SPI likewise correlated with Extreme Drought (D3) or greater. To further illustrate the drought’s impacts, winter wheat crop condition rated 62 and 46 percent very poor to poor in Texas and Oklahoma, respectively, as of March 27. It should be noted that many drought indicators in east-central Texas have reached the Exceptional Drought (D4) level, and if rain does not materialize soon, intensification of the current drought is likely. The remaining drought regions in northern and central Texas continued to depict worsening conditions as well, as the lingering benefits of late-winter rainfall quickly give way to dry, hot weather.
Central Plains: Showers in northern and eastern portions of the region contrasted with expanding dryness in the south and west. In central and eastern Nebraska, light to moderate rain and wet snow (0.50-1.0 inch liquid equivalent) was sufficient to negate expansion of D0 (Abnormal Dryness) but not enough to warrant reduction. Across the southern tier of Nebraska and into central Kansas, Moderate Drought (D1) was expanded to reflect soil moisture rankings in the lowest 10th percentile as well as the 6-month Standardized Precipitation Index which correlated to D1 or worse. In addition, remote sensing data (in particular, the Vegetation Health Index) depicted an increase in vegetation stress across southwestern Kansas; Kansas winter wheat was rated 35 percent very poor to poor as of March 27. In Colorado, precipitation was generally light (less than 0.75 inch) and confined to northeastern-most portions of the state’s D2 (Severe Drought) region. As of March 27, Colorado’s winter wheat was rated 55 percent very poor to poor.
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The West: Unseasonably heavy rain and mountain snow persisted across the Pacific Coast States, while drought intensified in lower portions of the Four Corners Region. Over the past 6 months, precipitation has tallied 50 percent of normal or less from southeastern Arizona into southern and central New Mexico, with the greatest departures (locally less than 30 percent of normal) in southern-most portions of the region. The corresponding 6-month Standardized Precipitation Index (SPI) indicated D3 conditions across the southeastern corner of Arizona and adjacent portions of southern New Mexico. Consequently, Moderate to Extreme Drought (D1-D3) was expanded in the lower Four Corner region. In northeastern Arizona, 3- and 6-month SPI likewise supported modest expansion of Moderate Drought (D1). The D0 region along the Nevada-California border was removed as updated seasonal SPI (6 and 9 month) indicated mostly favorable conditions. In contrast, heavy rain and mountain snow were observed from California into the Northwest, providing an additional boost to mountain snowpacks. Snow depths exceeded 100 inches at numerous locations in the Sierra Nevada, with some estimates in excess of 300 inches. Estimated weekly total liquid precipitation eclipsed 4 inches in northern portions of the California coast, and was locally more than 6 inches in the Sierra Nevada. In the Northwest, precipitation estimates of 2 to 8 inches (liquid equivalent) were noted from the Klamath Range into the Cascades and along the Pacific Coast.
Hawaii, Alaska and Puerto Rico: In Hawaii, showers (locally more than 2 inches) across eastern portions of the Big Island afforded some reduction of Moderate Drought (D1). Rain elsewhere in Hawaii was generally light and not sufficient to warrant any changes to the current drought depiction. In Alaska, dry, unseasonably warm weather prevailed, although no changes were made to the Abnormal Dryness region which remains due in part to a drier-than-normal winter. In Puerto Rico, showers (locally more than 3 inches) across the northwestern quarter of the island provided some relief to western portions of the Abnormally Dry (D0) region, while D0 was expanded slightly on the southwestern tip of Puerto Rico in response to 90-day precipitation totaling less than 50 percent of normal.
Looking Ahead: A series of storm systems will maintain wet, cool weather across the eastern third of the nation, providing some additional drought relief to the southern Mid-Atlantic and Southeastern states. In contrast, mostly dry, increasingly warm conditions are anticipated from the central Gulf Coast into the central and southern Plains. Out west, the story of the past month will continue, with another round of locally heavy rain and mountain snow expected by the weekend from central and northern portions of California into the Northwest. However, little if any precipitation from this system is expected to reach the lower Four Corners region.
The CPC 6-10 day forecast (April 5-9) calls for drier-than-normal conditions from the southern Great Basin and Four Corners region into the central and southern Plains. In contrast, above-normal precipitation is expected across the eastern quarter of the nation, although southern Florida may remain abnormally dry. Abnormal warmth across the Gulf Coast region will contrast with near- to below-normal temperatures across the remainder of the U.S., including Alaska.
Author: Eric Luebehusen, United States Department of Agriculture
http://www.drought.unl.edu/dm/monitor.html