National Drought Monitor for June 10, 2014
Summary
The previous 7 days featured an active weather pattern from the Central Great Plains to the Northeast. During the middle of last week, a low-pressure system moved from the Midwest to New England. After that, a slow moving low-pressure system moved across the southern Great Plains to the Tennessee Valley, spreading copious amounts of rain across much of the Great Plains, Midwest, and Southeast. Dry conditions persisted across the western portion of the contiguous 48 states. Strong trades persisted across Hawaii and Puerto Rico, bringing rains to northern and eastern facing slopes. A tranquil pattern persisted across most of Alaska, except the Alaska Panhandle.
Alaska, Hawaii, and Puerto Rico
A large swath of Alaska, roughly the southeastern quarter and the Panhandle, has been affected by dryness the past four months. Streamflows, commercial fishing, and hydroelectric power generation are suffering in some areas. The lack of rain has meant a lack of lightning-induced wildfires across the state’s interior, but conditions are favorable for fire development and quick expansion. The Funny River fire on the Kenai Peninsula has scorched 193,597 acres. Isolated locations across the Alaska panhandle received some rains (0.5 - 2.6 inches), but most of the state was dry for another week with only a handful of reports of more than 1 inch of rain across central Alaska. Conditions across interior should be closely monitored.
The east half of the state has been getting wet trade winds. Gages along the Big Island's east-facing and southeast-facing slopes are running at an above average pace for June, so the abnormally dry conditions there have been abated.
Rainfall was sparse for most of Puerto Rico this past week, with the south central portions of the island continuing the dry period. The D0 (abnormal dryness) was expanded to match the spatial coverage of the most intense 30- and 60-day deficits in AHPS precipitation measurements.
Mid-Atlantic and Carolinas
D0 (Abnormal Dryness) was expanded across small portions of North Carolina and South Carolina. The overall patterns in precipitation have been mixed, but a few areas standout as quite a bit drier than normal when measured over 30-, 60-, and 90-day periods. Some initial effects on agriculture are being reported to the NC-DMAC (North Carolina Drought Management Advisory Council).
Northeast
Abnormally dry (D0) conditions developed over portions of southern New England (Rhode Island and Massachusetts). D0 was introduced where precipitation is less than 50 percent of normal over 30 days and 14 days, and local streamflow reports are showing some abnormally low flows.
South Florida
No change was made to the depiction across South Florida. Recent rains (3.6 – 4.6 inches) across South Florida during June have arrested the developing dryness but were not enough to turn around the drought conditions.
Southern Great Plains, Central and Southern High Plains
Rainfall (2-3+ inches) fell across much of east Texas, prompting the removal of dry conditions from some portions of east Texas. Rainfall near the Texas coast was more limited in scope, so minor reductions in D0 (Abnormally Dry) and D1 (Moderate Drought) conditions were pursued near Wharton County. Beneficial rains (0.9 – 2.7 inches) fell across much the Texas and Oklahoma panhandles. The rains prompted the contraction of D4 (exceptional drought) across northern Oklahoma and the Texas panhandle, while D3 (extreme drought) was trimmed from the Oklahoma panhandle and southeastern Colorado. Subsoil conditions across Oklahoma and Texas are still quite dry with 71 and 59 percent of the reports indicating Very Short or Short of Moisture conditions, respectively.
As with the Texas Panhandle, some beneficial rains (0.8 – 2.5 inches) fell across eastern New Mexico. D3 (extreme drought) was subsequently trimmed back from in and around Quay and Harding Counties.
Huerfano County in Colorado has been dry as of late, and as part of a reassessment, D0 was reinstated. According to the Colorado Climate Center, recent rains have been beneficial for eastern Colorado, although reports are indicating that more rains are necessary to stem the tide of negative impacts due to the dry conditions. The heavier rains (0.7 – 3.0 inches) farther north in Colorado and Kansas, resulted in a nearly 1-category improvement in Colorado and near Hamilton County in Kansas.
The Midwest and Central Great Plains
Widespread rains from Minnesota to Kansas prompted the removal or reduction of drought across much of the Midwest and Central Great Plains. D1 was removed from most of Pipestone and Nobles Counties in Minnesota as rains up to 3.2 inches fell.
Across Iowa, some rains fell throughout the week, which helped alleviate drought conditions for much of the state. The remaining drought conditions are tied to longer term soil moisture deficits, linked to a dry second half of 2013. Page, Washington, and Calhoun Counties reported 12-month precipitation totals at about the 7th, 10th, and 5th percentile, respectively.
The moderate to heavy rains (0.6 – 5.1 inches) that fell across much of Nebraska resulted in drought reduction. Deeper profiles into the soil are still showing dryness, so the reduction was tempered by the long-term conditions, although the Extreme Drought (D3) was removed from central Nebraska as those areas received enough rains to recharge soil moisture down to 2-3 feet, according to calculations by the Nebraska State Climatologist.
Abnormally dry conditions were removed from Illinois and Missouri as well. Rains there were more widespread but slightly less intense (1.5 - 4.9 inches), resulting in recharges of soil moisture and increased runoff. The discharge of the La Moine River went from 30cfs to 3,000 cfs in a couple of days and is now above median since June 4 at Collmar, IL. The surrounding subsoils are still dry. According to NASS, the rains greatly improved the topsoil but did not make much difference to subsoil moisture in western Illinois. The percentages of subsoil in very short (23%) to short (46%) is a slight improvement from the week before, with field tiles not running yet, according to reports out of the Illinois State Climatologist’s office. In Missouri, COOP stations and the University of Missouri Agricultural sit at Novelty reported rainfall amounts of nearly 5 inches, with widespread 2-4 inches for the week across Central Missouri, prompting the removal of D0.
A 1-category improvement was implemented for most of eastern Kansas due to the widespread rains, with the rains missing much of western Kansas. Long-term subsoil moisture deficits continue to plague that state as well, so D3 (Extreme drought conditions were retained across western and southern Kansas with NASS reporting an 18 percentage point drop in topsoil reported as Short or Very Short of moisture, but 66 percent of subsoil reports indicating Short or Very Short conditions.
The Ohio Valley, Tennessee Valley and southern Appalachians
Moderate rains fell across Tennessee, northern Mississippi, and northern Alabama, so drought intensity and coverage were reduced. The Moderate Drought (D1) near the intersection of Alabama, Mississippi and Tennessee was removed as rains of 2.5 – 4.3 inches fell there, while rains of up to 7.9 inches were reported across Central Tennessee. Most of the rains missed Kentucky and southwestern Virginia, where drought conditions expanded and intensified. Across Kentucky, a station in Breathitt County recorded the 3rd driest May on record. Most stream gages in the area are currently at or below the 15th percentile. Standardized Precipitation Index values over 3 months (SPI-3) indicate very dry conditions across southwest Virginia and northeast Tennessee, so an area of Moderate Drought (D1) was introduced.
The southern Rockies, Intermountain West, and West Coast
According to the Colorado Climate Center and the NIDIS Upper Colorado River Regional Drought Early Warning System have been warm and dry for the past week over south and central Utah. This time of year is typically a dry period for the region, and May was a both cool and wet month. No changes were made to the Upper Colorado River Basin area or the rest of Utah.
Persistent dry conditions prompted the expansion of drought conditions across Idaho. Thirty-day SPI as of June 10 is showing dryness expanding, so D0 was expanded to where SPI3 and 30-day SPI show dry conditions, but tempered where SPI3 and 90-day percent of normal precipitation show wet conditions that were present in the winter and spring.
Drought conditions were expanded in Arizona as SPI3 and SPI6 values showed conditions drier than what was previously depicted. Fuel moisture values are low and fire danger is high for much of Arizona, outside of the major metropolitan areas, and that is where drought depiction was increased. Water Year-to-Date (less than 50% of average) and 1-year precipitation totals support the expansion as well.
Looking Ahead
Heavy rains are likely across the Great Plains from Oklahoma to Minnesota (5.1 inches is the maximum forecast value over Iowa). Widespread rains are also forecast over the Southeast and Florida. Little to no precipitation is forecast from Arizona and Utah to the West Coast.
The ensuing 5 days (June 17 -21, 2014) features enhanced chances for above-normal rainfall from the Mississippi Valley to the East Coast, except Florida. The odds also favor surplus rainfall over northwestern Alaska. Odds for below-median rains are increased across much of the west, west of the Continental Divide and across portions of southern Texas.
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