U.S. Drought Monitor Report for the Week Ending July 12 (Text)
Following is the text of the weekly U.S. Drought Monitor as released by the National Drought Mitigation Center in Lincoln, Nebraska:
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/./
Weekly Weather Summary: With the main storm track continuing over the northern half of the lower 48 States, high pressure over the southern Plains exacerbated the drought, keeping this area precipitation free and unseasonably hot (highs exceeding 110 deg F). Weak fronts stalled out across the Southeast, generating hit and miss showers and thunderstorms, with some locally heavy. Some Southeastern areas (southeastern Virginia and much of the Carolinas) received substantial rainfall. Heavy, widespread convective thundershowers inundated most of Florida while monsoonal showers continued and intensified over parts of the Southwest. Most of the Nation recorded near to above-normal temperatures, including parts of the West (notably California) which had observed a cold and wet spring and early summer.
The Upper Midwest, Northeast, and Mid-Atlantic: A series of frontal passages sparked showers and thunderstorms that dropped moderate to heavy rains (more than 2 inches) across southern Pennsylvania, New Jersey, the Delmarva Peninsula, and southern Virginia. 3 to 4 inches of rain soaked parts of southern New Jersey, while 4 to 8 inches inundated southeastern Virginia. Accordingly, a 1-category improvement was made where the greatest totals occurred, with D0 removed from southern New Jersey and south-central Virginia, D1 trimmed to D0 in the Delmarva Peninsula, and the D2 in the Delmarva Peninsula diminished. D2(AH) was kept where long-term deficits remained (90-days: 5-10 inches; 6-Months: 8-12 inches; 12-Months: 12-16 inches), even with this week?s beneficial rains. A 2-category improvement was made in southeastern Virginia (D1 to nothing) due to the excessive rainfall, and similar conditions extended southward into northern North Carolina (see Southeast text). The dam at Lake Chesdin which supplies water for the southwest suburbs of Richmond, VA, reached full capacity with water spilling over the top, effectively ending all water restrictions there.
In contrast, lesser amounts (0.5 to 1.5 inches) were recorded in Maryland and northern Virginia, maintaining conditions there. Farther north, short-term precipitation deficiencies (2 to 4 inches) have accumulated in northwestern Pennsylvania the past 30 days as only 25 to 50 percent of normal rain has fallen. With average 1-, 7-, and 14-day USGS stream flow levels in this region dropping into the lower tenth percentile, D0 was added.
Southeast: Scattered showers and thunderstorms pelted the Southeast, with substantial rains (more than 2 inches) falling on parts of the Carolinas, southern Georgia, most of Florida, and on portions of southeastern Louisiana and southern sections of Mississippi and Alabama. In contrast, dry and warm weather aggravated conditions in the lower Mississippi Valley (northern Louisiana, southern Arkansas, western Mississippi), slightly expanding the D0-D3 there. In North Carolina, 2 to 4 inches of rain pushed the western D0 edge eastward, while the western D1 border in northern North Carolina was edged eastward. Similarly, the western D2 boundary in eastern North Carolina was pushed eastward, while the D3 was removed from Dare County where 3 to 5 inches of rain fell. Additional rains will be needed, however, to further improve drought as any future prolonged periods of summer dryness and warmth could quickly deteriorate conditions. In southeastern North Carolina, however, D3 remained where totals were inadequate (less than an inch). In South Carolina, heavy rains (2 to 4 inches) in the west and east-central improved D0 and D1 conditions, but elsewhere the rains were too scattered in nature for improvement. In Georgia, 1-category relief was limited to extreme southern portions where 2.5 to 3.5 inches trimmed away the southern D4 edge. In Florida, widespread, heavy summer rains brought large improvements to the state, especially in the southern half. In Florida’s Big Bend, East-Central, and South, widespread 10 plus inches of rain the past 30 days (3 to 6 inch surpluses), and over 8 inch excesses the past 60 days, have greatly eased drought conditions, including river flows. D4(H) conditions in southern Florida were limited to metro Broward County as long-term indicators, including the very low Lake Okeechobee levels, well levels in Palm Beach and Broward counties, and substantial precipitation deficits since January 1, 2011, and October 1, 2010. Farther west, some slight improvements were made in southern Alabama and Mississippi along the D2 border where more than 2 inches of rain fell, and in north-central Alabama where D0 was alleviated. In northern and eastern Arkansas, 1.5 to 2.5 inches of rain erased D0; however, farther south, little or no rain and highs topping 100 deg F expanded D0 to D2 into western Mississippi and southern Arkansas. The Impact Type line was modified to H-only across the northern drought border as recent rains have eased or erased short-term deficits from northern Alabama to northern North Carolina.
The Southern and Central Plains: Widespread heavy showers and thunderstorms dumped heavy rains (2 to 5 inches) on the northern and central Plains, but completely missed the southern third of the Plains (from southern Kansas southward to the Texas-Mexico border). To make matters worse, excessive heat accompanied the dryness as highs hit triple-digits. Maximums even topped 110 deg F in southern Kansas, central Oklahoma, and north-central Texas, and weekly temperatures averaged 7 to 10 deg F above normal there. In Texas, based upon the updated SPI blends at 12 GMT July 12, conditions deteriorated a category in northeastern Texas, while adjustments for additional slight improvements were made in extreme southern Texas (due to rains from Tropical Storm Arlene 2 weeks ago). Across the state, huge deficits have accumulated. In Beaumont, TX, 2011 rainfall has been 8.80 inches versus a normal of 30.93 inches (26 percent of normal). This total (8.80 inches) is closer to what Midland, TX, normal receives. Unfortunately, Midland is in an arid climate regime, and Beaumont is not. From October to June, many locations have recorded one of the driest such periods on record (e.g. San Antonio, Del Rio, Austin), and this dryness has been accompanied by near-record warmth this summer. In contrast, a deluge late in the week in north-central Texas (Hall, Childress, Briscoe, and Motley counties) brought this area back into D3. Farther north, however, no rain and plenty of heat quickly deteriorated conditions in western and central Oklahoma and south-central Kansas, and the D2-D4 area expanded eastward and northward by a category. From the USDA/NASS, percent of pasture and range lands rated poor or very poor were: Texas 86; Oklahoma 69; Kansas 40. Similarly, summer crops have taken a beating. 78 and 58 percent of cotton was rated poor or very poor in Oklahoma and Texas, while the sorghum crop in New Mexico, Texas, and Oklahoma was rated 50, 51, and 44 percent poor or very poor. 62 percent of the Texas corn was categorized poor or very poor.
In sharp contrast, heavy rains across the north-central Plains alleviated abnormal dryness in southern Nebraska, and improved conditions by a category across the northern half of Kansas (and into central Colorado, see Southwest text). There was a sharp cut off from the ample rains to no rain across central Kansas, which also marked the northern extent of this week?s triple digit heat.
The Southwest: The summer monsoon continued across Arizona, southern Nevada, Utah, and into Colorado, but bypassed New Mexico and western parts of Texas and Oklahoma. 1 to 2 inches of rain fell on southern and central Arizona, extreme southern Nevada, south-central Utah, and across most of Colorado except southeastern sections. The moisture also tempered the heat in this region, with average temperatures only slightly above normal. Accordingly, where an inch or more fell near any drought border, some slight improvement was made. This included parts of the D1 through D4 edges in southern and central Arizona, and elimination of the D0 in parts of western Arizona. Interestingly, Douglas, AZ, received more rain in 9 MINUTES (0.30 inches on July 6 starting at 4:51pm) than in the past 9 MONTHS (only 0.27 inches since October 1, 2010). In Colorado, another wet week, especially in the north-central and eastern sections, called for a 1-category improvement in central portions of the state. Farther south, however, rainfall was much less (0.1 to 0.5 inches), and conditions deteriorated (D3 and D4) in eastern Conejos, western Costilla, and western Rio Grande Counties. Elsewhere, enough rain fell to maintain conditions, but not enough to warrant improvement. Even with the rains, Arizona pasture and range conditions were rated 63 percent poor or very poor, while New Mexico stood at a horrendous 91 percent as of July 11 according to USDA/NASS.
Puerto Rico, Hawaii, and Alaska: In Puerto Rico, the newly added D0 area in the northwest was quickly eradicated as 3 to 4 inches of rain fell this week, effectively raising average stream flow levels to near-normal flows the past 1-, 7-, 14-, and 28-days. Reports from the island indicate all vegetation is green and lush as above-normal spring and summer rains have fallen on much of the island.
In Hawaii, light to moderate showers fell on Kauai and Oahu, and on the windward sides of Maui and the Big Island. The effects of surplus spring rainfall produced improvements over leeward portions of the Big Island and Maui, but this trend is expected to end as drier and warmer conditions take hold during the summer dry season. No changes were made this week, but if the drying trend continues next week on parts of the leeward Big Island, some degradation may occur.
In south-central Alaska, light precipitation (0.5 inches or less) fell while the southeastern Panhandle received 0.5 to 1.5 inches. The greatest rains fell on the non-drought regions of southwestern (1.5 to 2.5 inches), western (0.5 to 1.5 inches), and eastern (0.5 to 1 inch) Alaska, while temperatures statewide averaged close to normal. Accordingly, conditions were left unchanged; however, with USGS average stream flows percentiles running low in the Kenai Peninsula, this area will be watched closely.
Looking Ahead: For the ensuing 5 days (July 14-18), a swath of heavy rain (more than 2 inches) is expected in the Southeast, from eastern Louisiana to South Carolina, over areas with D2 to D4 conditions. Moderate to heavy rains should also fall from the northern Rockies to the upper Midwest. Unfortunately, the southwest monsoon is forecast to diminish across the Four Corners Region, and the southern Plains will remain dry. Showers should continue in Florida, although the heaviest rains should be in the north, with lower totals in the south. Temperatures are expected to average below normal in the West, above normal from the Rockies to the Appalachians, and seasonable along the East Coast.
The CPC 6-10 day outlook (July 19-23) indicates above-normal monsoon rainfall in Arizona and Utah, but continued subnormal precipitation to the east (eastern New Mexico, western Texas, and into the central Plains and lower Missouri Valley). Above normal rainfall should occur in the upper Midwest southeastward into the Carolinas and southward to the Gulf Coast. New England should also experience subnormal precipitation, as should southwestern Alaska. Abnormal warmth should encompass most of the Nation, especially the Great Lakes region and Midwest, and southwestern Alaska, while subnormal temperatures will be limited to the Far West, southern Florida, and eastern Alaska.
SOURCE: National Drought Mitigation Center
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