Drought - June 2011
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Contents Of This Report:
National Drought Overview
Detailed Drought Discussion
June 2011 was a warm and dry month (19th driest and 26th warmest, based on data back to 1895) when weather conditions are averaged across the country. But this reflected regional extremes (in both monthly precipitation and temperature) which resulted from persistent weekly regional patterns of precipitation (weeks 1, 2, 3, 4, 5) and temperature (weeks 1, 2, 3, 4, 5) anomalies throughout the month. Drought conditions improved in Hawaii, where the percent of the state in moderate to severe drought fell from 33 percent last month to 16 percent this month. Drought intensified in the Southern Plains, along the Gulf Coast, and into the Mid-Atlantic Coast, where rainfall was below normal for yet another month. USDM statistics rated 63 percent of the Southeast in moderate to exceptional drought at the end of June compared to 51 percent at the end of May. In the Southern Plains, the percent area in the worst category of drought (exceptional drought) rose from 28 percent to 47 percent. The drought was accompanied by numerous wildfires, dessicated soils, failed crops, and hot temperatures, with more than 4000 daily high temperature records tied or broken. In parts of the Southwest to Gulf Coast, this year's drought eclipsed the drought of record in terms of intensity as measured by the Palmer Hydrological Drought Index. About 28 percent of the contiguous U.S. was experiencing moderate to exceptional (D1-D4) drought by June 28, about two percent more than at the end of May. But nearly 12 percent was in the exceptional (D4) category, about twice the value for last month and reflecting a steady rise in drought extent for this category over the last 13 consecutive weeks.
By the end of the month, the core drought areas in the U.S. included:
- a large area of moderate (D1) to exceptional (D4) drought across the Southwest, Southern and Central Plains, and Southeast;
- areas of moderate to severe (D2) drought along the Mid-Atlantic Coast; and
- parts of Hawaii, where moderate to severe drought persisted.
The weather pattern over the contiguous United States during June 2011 was a continuation of an upper-level high pressure ridge over the southern to eastern U.S. and an upper-level low pressure trough over the Northwest, with the storm track mostly keeping to the northern states. Weather systems occasionally moved across the middle of the country toward the east, dragging weak fronts into the Southeast. Hot and dry weather was associated with the upper High, while cooler-than-normal weather dominated the Northwest.
More than 4000 daily high temperature records were tied or broken in June, mostly east of the Rockies, and there were 159 reports of the record hottest temperature for June and 42 reports of all-time record hottest temperature ever. Texas had the hottest June in the 1895-2011 record while 12 other states, from New Mexico to New Jersey, ranked in the top ten warmest category. The Residential Energy Demand Temperature Index (REDTI) — a population-weighted index of energy demand — for June 2011 ranked as the seventh highest June value in the 1895-2011 record. As estimated by the REDTI, the national residential energy consumption was eight percent above the long-term average consumption. This month marks the seventh consecutive June that the REDTI was above the long-term average.
June 2011 was the driest June for New Mexico and ranked in the top ten driest category for four other states from Arizona to Florida. Numerous wildfires accompanied the hot and dry weather in the Southwest to Southeast this month. Nationwide, 1.35 million acres burned during June, bringing the year-to-date acreage burned to approximately 4.8 million acres — the most on record for the period and more than twice the long-term average.
Texas, New Mexico, and Louisiana had the driest year-to-date (January-June) in 2011 and Florida had the driest 12-month period (July-June). This persistent dryness intensified drought across parts of the Southwest to Southeast. While the Southern Plains' 1950s drought of record is unsurpassed in terms of duration, the current drought in parts of Texas is more intense than the 1950s drought when measured by the Palmer Hydrological Drought Index. Nationally, the size of the drought footprint (moderate to exceptional drought as measured by the USDM) grew slightly from 26 percent to 28 percent, but the drought intensified during June with the exceptional drought area doubling from 6 percent to 12 percent.
While blanketing the southern U.S. with hot and dry weather, the upper High effectively blocked the Gulf of Mexico moisture from feeding severe storms, resulting in only 177 preliminary tornado reports during June, which is below the national average for the month. It also helped deflect tropical systems away from the U.S., with Tropical Storm Arlene being shunted into central Mexico at the end of the month.
In the Northwest, beneath the upper-level low pressure trough, temperatures were below normal with Idaho, Oregon, and Washington ranking in the top 20 coolest for June. The circulation pattern gave California the wettest June on record and Illinois the eighth wettest, with above-normal precipitation in several northern Plains, Midwest, and New England states. Heavier than normal precipitation and prolonged snowmelt during the spring caused June flooding in Idaho, Montana, Utah, and Washington. In addition to flooding along the length of the Missouri River, the Souris River in North Dakota submerged parts of Minot. The persistence of the precipitation patterns over the last several months created a notable imprint on the nation's soil moisture, with excessively wet soils in the north and extremely dry soils in the south. This soil moisture pattern is international — with the dry end extending into Mexico while the wet end extended into the southern Canadian Prairies with the northern Prairies dry.
When averaged together, the mixture of temperature and precipitation extremes gave the U.S. the 26th warmest and 19th driest June in the 117-year record. Averaging extremes tends to cancel them out. But when extremes are combined cumulatively, like in the U.S. Climate Extremes Index (CEI), they tell a different story. The large increases in heavy rain days, long dry spells, and hot temperatures over the last three months combined to produce an April-June 2011 CEI of 42 percent, which is twice the value it would have in a "normal" year. The April-June 2011 CEI ranks as the second largest April-June CEI in the 1910-2011 record, behind April-June 1934.
Cold fronts and low pressure systems moving in the storm track flow are influenced by the broadscale atmospheric circulation. Two such large-scale atmospheric circulation drivers were essentially neutral during June. The equatorial Pacific was in an ENSO-neutral state, which means the La Niña has officially ended even though atmospheric circulation anomalies still reflected some aspects of La Niña. The Pacific/North American (PNA) pattern was also neutral and thus not a significant player in the nation's weather this month. But two other large-scale atmospheric circulation drivers were influential during June 2011. The first was the North Atlantic Oscillation (NAO) pattern, which was negative for most of the month. A negative NAO this time of year (summer, represented by July on the NAO teleconnection maps) is typically associated with warmer-than-normal temperatures and drier-than-normal conditions in the southern Plains and Southeast, cooler-than-normal weather in the Northwest and northern Plains, and wetter-than-normal conditions in the northern Plains and Midwest. The second atmospheric circulation index was the Arctic Oscillation (AO) pattern, which was slightly negative for most of the month. A negative AO this time of year (April-June) is typically associated with coolness in the northern Plains and Great Lakes to Northeast, dryness in the Southeast to Northeast and coastal Northwest, and anomalous wetness in northern California and the northern Plains.
The pattern of observed temperature anomalies for June 2011 and the last three months (April-June) is a very good match for the NAO pattern for July (summer). The June 2011 and April-June 2011 precipitation patterns are a reasonable match for the NAO and AO patterns in the southern Plains and Southeast.
Palmer Drought Index
The Palmer drought indices measure the balance between moisture demand (evapotranspiration driven by temperature) and moisture supply (precipitation). The Palmer Z Index depicts moisture conditions for the current month, while the Palmer Hydrological Drought Index (PHDI) and Palmer Drought Severity Index (PDSI) depict the current month's cumulative moisture conditions integrated over the last several months. As seen on the June 2011 Palmer Z Index map, like last month, low precipitation and hot temperatures resulted in short-term drought across much of the Southwest, Southern to Central Plains, Southeast, Mid-Atlantic, and parts of the Northeast and southern Great Lakes this month. Wet conditions are evident on the Z Index map over a large area from the West to the Northern Plains, and parts of the Mid-Mississippi and Ohio valleys. Compared with the May 2011 PHDI map, the June 2011 PHDI map indicates that drought conditions intensified from the Southwest and Southern Plains, along the Gulf Coast, and up into the Mid-Atlantic Coast; moist conditions intensified across parts of the West, Northern Plains, and Ohio Valley; and moist conditions lessened in parts of the Northeast, Great Lakes, and Pacific Northwest. The June 2011 PHDI map also reflects the long-term nature of the drought conditions. The Z Index and PHDI maps in combination show, with the exception of parts of the Northeast and Great Lakes, that it rained where it was already wet and was drier than normal over the existing drought areas.
Standardized Precipitation Index
The Standardized Precipitation Index (SPI) measures moisture supply. The SPI maps here show the spatial extent of anomalously wet and dry areas at time scales ranging from 1 month to 24 months. Dryness is evident across much of the Southwest, Southern Plains, Southeast, and Mid-Atlantic at the 1 month to 12 month time scales. Severe to exceptional dryness stands out on the maps for parts of the Southwest, Southern Plains, and Southeast at 1 month, but exceptional dryness is widespread from 2 months to 9 months, and still quite dominant at 12 months along the Gulf Coast and southern Georgia. The dryness in parts of the broad Southwest to Southeast drought area is evident even at 24 months. While in the northern areas, even down into the Mid-Mississippi Valley, unusually wet conditions are evident at all time scales from 2 to 24 months. This illustrates the persistence of the dry and wet areas. The unusual wetness was not as widespread at the 1 month time scale.
Agricultural and Hydrological Indices and Impacts
Drought conditions were reflected in numerous agricultural, hydrological, and other meteorological indicators, both observed and modeled. Across the drought area from the Southwest to Mid-Atlantic, streamflows were low, some groundwater well stations were at or near record low levels for this time of year, soil moisture was depleted, water restrictions were implemented in many communities, and pastures, rangeland, crops, and natural vegetation were ravaged. Parts of the Southwest and Southern Plains had no days with rain at all in June. There was some indication (Soil Water Index) that vegetative stress extended into western New York and Pennsylvania. A large area of dry soils was indicated for Mexico connected to the Southern Plains dryness. The excessive heat across the southern and eastern U.S. increased evaporation and placed additional stress on vegetation. This summary is based on the following observed and modeled indicators:
- USGS (U.S. Geological Service) observed streamflow;
- NOAA Climate Prediction Center (CPC) modeled runoff anomalies and percentiles;
- VIC (University of Washington Variable Infiltration Capacity macroscale hydrologic model) 1-, 2-, 3-, and 6-month runoff percentiles;
- NLDAS (North American Land Data Assimilation System) modeled streamflow anomalies and percentiles;
- NLDAS model runoff anomalies and percentiles;
- USGS groundwater observations (real-time network, climate response network, total active network);
- USDA (U.S. Department of Agriculture) observed soil moisture conditions and comparison to 5-year average and 10-year average;
- the Palmer Crop Moisture Index (CMI), which steadily worsened and expanded throughout the month (weeks 1, 2, 3, 4, 5);
- CPC modeled soil moisture anomalies and percentiles for end of June (soil moisture anomaly change from May 31 to June 30);
- CPC's Leaky Bucket model soil moisture percentiles;
- NLDAS modeled soil moisture percentiles for the top soil layer and total soil layer;
- VIC modeled soil moisture percentiles;
- USDA observed pasture and rangeland conditions;
- Vegetation Drought Response Index (VegDRI);
- satellite-based Vegetation Health Index (VHI);
- the USGS agro-hydrologic model (Soil Water Index, Water Requirement Satisfaction Index);
- rainfall observations (plotted by the USGS and NOAA National Weather Service);
- percent of normal precipitation and precipitation percentiles (CPC, High Plains Regional Climate Center station observations, Leaky Bucket model);
- USGS number of days with precipitation and number of consecutive dry days;
- temperature departures from normal and percentiles;
- number of record daily high temperatures, record monthly high temperatures, and all-time record high temperatures set in June 2011 (from NCDC's daily records analysis).
According to the Electric Reliability Council of Texas, operator of the state's major power grid, electricity demand peaked at 62,752 megawatts on the 27th, a record for June. As noted by the USDA on July 3rd, 51 percent of the nation's rangeland and pastures were rated in good to excellent condition, while 27 percent were rated very poor to poor. A year ago, those numbers stood at 65 and 11 percent, respectively. In terms of state-level values, more than one-third of the rangeland and pastures were rated in very poor to poor condition in New Mexico (89%), Texas (84%), Arizona (67%), Oklahoma (60%), South Carolina (58%), Louisiana (55%), Georgia (50%), Mississippi (41%), Alabama (39%), Colorado (39%), and Kansas (39%). By early July, row-crop conditions were mostly good to excellent for major Midwestern commodities such as corn (69 percent good to excellent on July 3) and soybeans (66%). However, the southern drought was taking a significant toll on crops such as cotton (28 percent good to excellent; 41 percent very poor to poor) and peanuts (30 percent good to excellent; 27 percent very poor to poor). On July 3, more than half of the cotton crop was rated very poor to poor in Oklahoma (73%) and Texas (57%).
June was drier than normal for many southern Alaskan stations. Below-normal precipitation was widespread for the last 2 to 3 months, which contributed to the 15th driest April-June statewide. Dryness in the southern and central portions of the state is reflected in precipitation deficits at longer time scales (6, 12, 24, 36 months) and in June monthly streamflow for the south central basins. The June 28th USDM map had a fourth of the state in the abnormally dry category.
June had a mixed rainfall pattern over Puerto Rico. There were a few areas with below-normal rainfall at longer time scales (2, 3, and 6 months, year to date, and water year to date [October-June]), but the June 28th USDM map had no drought or abnormally dry areas on the island.
Most stations in the northern Hawaiian Islands were wetter than normal during June, but stations in the southern drought areas were mostly drier than normal. Nevertheless, drought conditions continued to improve, with moderate to severe drought affecting only 16 percent of the state at the end of June compared to 33 percent at the end of May. But long-term rainfall deficits remained at most time scales (last 2, 3, 6, 12, 24, 36 months).
On a statewide basis, June 2011 was drier than normal for 18 states, but the hardest hit were six southern states from Arizona to Florida, five of which ranked in the top ten driest category based on the 1895-2011 record. For the Southern Plains states, especially Texas, the dryness extends back to October 2010, with several "seasons" ranking as the driest on record.
Texas had the driest March-June, February-June, January-June, December-June, November-June, October-June, September-June, and August-June. New Mexico had the driest June, April-June, March-June, February-June, January-June, December-June, and November-June on record. Louisiana ranked driest for January-June and December-June. Florida had the driest September-June and July-June. Other states with near record dryness (April-June, July-June) include Georgia with the second driest May-June and Oklahoma with the third driest August-June. In addition to having the fifth driest June and second driest April-June, Texas had the hottest June and April-June.
The extreme dryness in the Southern Plains resulted in a rapid increase in the percent area of the region experiencing drought. Nearly half (47 percent) of the South region was rated in exceptional drought, which is nearly double the value from the end of May and the largest percentage in the 11-year USDM record. Similarly, Texas has had a rapid increase in the percent area of the state experiencing drought, with nearly the entire state affected by moderate to exceptional drought according to the June 28th USDM, nine-tenths (91 percent) in the extreme to exceptional drought categories, and nearly three-fourths (72 percent) in the exceptional drought category.
On a more localized basis, record dryness has occurred for at least one climate division in the Southwest, Southern Plains, Southeast, or Mid-Atlantic Coast at every time scale from the one-month period, June 2011, through the 12-month period, July 2010-June 2011:
As reported in the media, some people have likened this year's drought to the droughts of the 1930s and 1950s. The USDM goes back only 11 years. But the PHDI has a 110+ year period of record. The 2011 drought has been going on long enough, and the dryness has been severe enough, that the PHDI for some climate divisions in the Southern Plains and Gulf Coast is now as severe or more severe than the PHDI for the 1950s southern drought of record:
It should be noted that, in all of these cases, the earlier droughts lasted much longer than the 2011 drought to date. For East Texas and the Gulf Coast, earlier droughts (1920s or 1930s) were more severe than the 1950s drought. For northern and western Louisiana, the 2011 drought is as severe as those earlier droughts. For coastal Louisiana and Mississippi, the drought of record occurred in 2000; the 2011 drought ranks second in severity after the 2000 drought.
The precipitation pattern over the West in June was mixed and characterized by extremes, with New Mexico having the driest June in the 1895-2011 record and California the wettest. June was drier than normal in parts of the Pacific Northwest, Central Rockies, and Intermountain Basin, but this did little to change the overall pattern for the water year to date (October-present) — extremely dry conditions have been persistent from Arizona and New Mexico into eastern Colorado, but abundant precipitation has fallen across the rest of the West. This is evident in both the low elevation station precipitation as well as the high elevation (SNOTEL) station precipitation and snow water equivalent, modeled soil moisture, and PHDI. The winter snowpack has mostly melted out of the western mountains, although some higher elevation stations still have several inches of snow which is well above normal for this time of year. It should be noted that snowpack percentages can be highly skewed at this time of year because normals are so low for this late in the season. An analysis of early data by the USDA indicated that reservoir levels were, on average, below normal in New Mexico, where drought was an issue, to near or above normal in the other western states. According to the USDM, 19 percent of the West was experiencing moderate to exceptional drought at the end of June, slightly more than May, while the Palmer Drought Index statistic was about 14 percent, also slightly more than last month. When the statistics for the Arizona-New Mexico-Colorado drought area (the Southwest drought area) are aggregated, the percent area in moderate to exceptional (USDM categories) drought has fluctuated between 60 and 70 percent for the last four months, but the percent area in the exceptional and extreme to exceptional categories has shown a steady increase, with 7 percent in extreme to exceptional drought at the end of March rising to 38 percent at the end of June.
A more detailed drought discussion, provided by the NOAA Regional Climate Centers and others, can be found below.
West — Upper Colorado River Basin — Pacific Islands
As noted by the Southeast Regional Climate Center, precipitation was generally below normal across the Southeast in June, with monthly totals ranging between 25 and 75 percent of normal across most of the region. The driest locations (less than 25 percent of normal) were along the coastal plain of North and South Carolina and along the Florida Keys. Key West, Florida recorded 0.71 inch (18.0 mm) of rain for the month, or 16 percent of normal. Florence, South Carolina recorded only 0.30 inch (7.6 mm), a deficit of nearly four inches (101.6 mm). The wettest locations (greater than 200 percent of normal) were in western North Carolina, southwest Florida, Puerto Rico, and the U.S. Virgin Islands. Interestingly, there were a few cases of coastal stations in close proximity that reported strikingly different monthly rainfall totals. For example, Miami Beach, Florida recorded its driest June on record with 1.15 inches (29.2 mm) of rainfall, while just seven miles away the Miami International Airport recorded 12.22 inches (310.4 mm) of rainfall.
For the second consecutive year, meteorological summer began with exceptionally warm temperatures across the Southeast region. Mean temperatures in June were between 4 and 6 degrees F (2.2 and 3.3 degrees C) above normal across most of the region, with exception to the Florida Peninsula, Puerto Rico, and the U.S. Virgin Islands. Several locations in the Southeast experienced their warmest June on record, including Birmingham, Alabama; Mobile, Alabama; Columbus, Georgia; and Cape Hatteras, North Carolina. The persistence of the warm temperatures was also noteworthy. In Columbia, South Carolina, the maximum temperature reached 90 degrees F (32.2 degrees C) or higher on all 30 days of the month, breaking the old record of 27 days set back in 1911 and 1952. Savannah, Georgia also recorded 90 degree F and higher temperatures on all 30 days, extending a streak of 90 degree and higher temperatures that began in May.
Drought conditions continued to worsen across parts of the Southeast in June. Most notably, the regions of extreme and exceptional drought (D3 and D4) expanded across parts of northern Florida, southern Alabama and Georgia, and southeast Florida. The region of severe drought (D2) expanded across eastern North Carolina. The continued dryness in these regions sustained several lightning-generated wildfires, prompting numerous air quality alerts in parts of eastern North Carolina, South Carolina, and Georgia. The extreme heat and dryness also had a negative impact on agriculture. Hay production was down and this created concern among farmers trying to feed cattle and livestock. Farmers in Alabama reported rotted peanuts and were beginning to replant with cotton and soybeans. The corn crop was generally reported to be in poor condition across much of the region, except in Virginia. In south Florida, continued water restrictions limited sugarcane growth. Water supplies were severely affected in some communities. Groundwater levels were near record low levels across parts of central and southern Georgia, requiring municipalities to increase the depth of their wells to maintain water supplies. Towards the end of the month, dust from the Sahara Desert was transported across the Atlantic Ocean and into the Caribbean. Haze and poor visibility from the dust persisted for several days across Puerto Rico and the U.S. Virgin Islands and contributed to a spike in respiratory disease.
As explained by the Southern Regional Climate Center, with the exception of Tennessee, June proved to be a very dry month in the Southern region. In Tennessee, there was a lot of spatial variation in precipitation totals with the eastern half averaging near normal to above normal, while in the western half, stations averaged near normal to below normal. The state averaged 5.58 inches (141.73 mm) of precipitation and it was the eighteenth wettest June on record (1895-2011). Elsewhere, most stations averaged below 50 percent of normal precipitation. Precipitation late in the month helped augment precipitation totals in Louisiana and therefore most of the state ended up averaging 50 to 90 percent of normal. The state average precipitation total in Louisiana was 3.10 inches (78.74 mm). A similar situation with similar values occurred in Mississippi. The state average precipitation total for the month in Mississippi was 2.83 inches (71.88 mm). In Arkansas, Oklahoma and Texas, conditions were much drier, with dozens of stations receiving less than twenty-five percent of normal precipitation. Arkansas averaged only 1.58 inches (62.23 mm) for the month and it was the eleventh driest June on record (1895-2011). Oklahoma and Texas were the driest states. Oklahoma experienced its fourth driest June on record (1895-2011), while Texas experienced its fifth driest June on record (1895-2011). The state average precipitation totals for Oklahoma and Texas were 1.18 inches (29.97 mm) and 0.99 inch (25.15 mm), respectively.
June was a very warm month for the entire Southern region, with most stations averaging at least 4 degrees F (2.22 degrees C) above the monthly normal. The highest temperature anomalies occurred in northern Texas and through most of Oklahoma. Temperatures there averaged between 6 to 10 degrees F (3.33 to 5.56 degrees C) above expected monthly values. The region as a whole had an average temperature of 83.43 degrees F ( degrees C), which was the second warmest June on record (1895-2011). Texas had a state average temperature of 85.20 degrees F (29.56 degrees C), which was the warmest June on record (1895-2011). Oklahoma experienced its second warmest June on record (1895-2011) with a state average temperature of 83.40 degrees F (28.56 degrees C). Louisiana also had its second warmest June on record (1895-2011). The state average temperature for the Bayou State was 83.50 degrees F (28.61 degrees C). Both Arkansas and Mississippi experienced their sixth warmest June on record (1895-2011) with state average temperatures of 81.60 degrees F (27.56 degrees C). For Tennessee, it was the twelfth warmest June (1895-2011) with a state average temperature of 76.60 degrees F (24.78 degrees C).
Extreme dryness coupled with anomalously high temperatures throughout the Southern region has not led to much of a change in areal coverage of drought in general, but it has led to dramatic changes in drought intensity. As was the case last month, northern Mississippi and Tennessee remained drought free. Dryness throughout most of Arkansas and eastern Oklahoma has led to the introduction of D0, or abnormally dry conditions. The biggest changes in drought intensity occurred in the states of Louisiana, Texas and Oklahoma. As of May 31, 2011, 60.31 percent of Louisiana was in extreme (D3) drought or worse, with only 10.38 in exceptional (D4) drought. As of June 28, 2011, those numbers increased to 90.12 percent in extreme (D3) drought or worse and an astounding 63.50 percent in exceptional (D4) drought. Similarly, in Oklahoma, there was an 11.19 percent areal coverage increase in extreme (D3) drought or worse and a 22.58 percent areal coverage increase in exceptional (D4) drought. In Texas, there was a 9.55 percent increase in the areal coverage of extreme (D3) drought or worse, and a 21.67 percent areal coverage increase in the amount of exceptional (D4) drought. As of June 28, 2011, 72.32 percent of Texas, 32.55 percent of Oklahoma and 63.50 percent of Louisiana were designated as exceptional drought.
According to the Business Insider, the entire state of Texas was now declared a natural disaster zone. According to the Texas forest service, almost all counties in Texas were under a burn ban. On June 8, 2011, mysanantinio.com reported that Texas was experiencing its third worst drought on record. According to Texas State Climatologist Dr. John Nielson Gammon, the June statewide Palmer Drought Severity Index was -6.37. This has been exceeded only twice — in June 1956 with a value of -6.54, and in June 1918 with a value of -6.41.
As summarized by the Midwest Regional Climate Center, June precipitation in the Midwest varied considerably. Monthly totals were two to three times normal from southeast Iowa to southeast Illinois and also at the northern edge of Lower Michigan. Totals were less than half of normal rainfall in southwest Missouri and near the Michigan-Ohio border. Drought was scarce in the Midwest during June. A small area of Moderate Drought was introduced in northeast Minnesota only to revert to Abnormally Dry in the USDM the following week. More than 750 daily precipitation records were set in the Midwest during the month. In Illinois, statewide precipitation ranked as the 8th wettest June since 1895. Flooding along the Missouri River persisted through the month with major flooding in western Iowa and northwest Missouri.
June temperatures were well above normal at the beginning of the month but cooled to below normal later in the month. Averaged for the month, temperatures were 3 degrees F (2 degrees C) below normal in northern Minnesota and 5 degrees F (3 degrees C) above normal in southern Missouri. Minimum temperatures were warmer, compared to normal, than maximum temperatures. Nearly 2000 daily temperature records were set in June with hundreds each of record high maximums (832), record low maximums (430), and record high minimums (692) but relatively few record low minimums (30).
Planting progressed at a furious pace in late May and early June when favorable conditions finally allowed farmers an opportunity for field work. Planting season was compressed into a shorter than normal window but most of the intended corn and soybean acres were planted with the expectation of sufficient time to mature.
As noted by the Northeast Regional Climate Center, after four months in a row with above normal precipitation, the Northeast averaged drier than normal in June. The regional rainfall total was 3.74 inches (95 mm) or 89 percent of normal. Four states, Connecticut (127 percent), Massachusetts (126 percent), Rhode Island (107 percent), and Vermont (106 percent) averaged wetter than normal; departures among the drier than normal states ranged from 63 percent in Maryland to 99 percent in Maine. Drought concerns were returning to the Mid-Atlantic region. As of June 28, 2011, the USDM reported D1 (moderate) drought in southeastern Maryland and southern Delaware and D0 (abnormally dry) conditions elsewhere in eastern Maryland and northern Delaware, as well as the southern third of New Jersey. Temperatures in the Northeast were above normal for the sixth consecutive month. It was the 6th warmest June since 1895 in Delaware, the 8th warmest in Maryland, and the 10th warmest in New Jersey. Four of the six New England states averaged below normal.
As explained by the High Plains Regional Climate Center, large areas of above and below normal precipitation occurred this month. Areas of southern Colorado and southern Kansas received little to no precipitation, while a swath of above normal precipitation extended through central North Dakota, South Dakota, and into Nebraska. Alamosa, Colorado, which was experiencing extreme drought the entire month, tied for its driest June on record (period of record 1906-2011). This was the third June on record in which Alamosa did not receive any measurable precipitation (other years included 1980 and 1946). Elsewhere, some locations received well over 200 percent of normal precipitation with Pierre, South Dakota being this month's wet spot. Total precipitation at Pierre this June was 8.31 inches (211 mm) which was 4.82 inches (122 mm) above normal and enough to set a new record (period of record 1893-2011). The old record of 7.66 inches (195 mm) occurred just a few years ago, in 2008. Meanwhile, flood warnings along the Missouri River continued the entire month. Numerous towns and hundreds of thousands of acres of farmland have been impacted by the flooding. In addition, many roads were closed including parts of I-29 in Iowa, Missouri, and South Dakota. According to the South Dakota State Climate Office, some residents of Pierre, Fort Pierre, and Dakota Dunes evacuated their homes. Major flooding continued this month along not only the Missouri River, but also the Souris River which flows south from Canada into North Dakota. Many towns along the river were impacted including Minot, Burlington, Sawyer, and Velva. According to the North Dakota State Climate Office, in Minot, the state's fourth largest city, 11,000 people were forced to evacuate in just 24 hours and numerous homes and businesses were damaged in the flood. The river crested at a record 1561.72 feet which surpassed the old record of 1558 feet set in 1881.
June 2011 temperatures were generally lower than normal in the north and higher than normal in the south across the High Plains region. Average monthly temperatures ranged from near normal to 6.0 degrees F (3.3 degrees C) below normal in the Dakotas, Wyoming, Nebraska, and northern Colorado. Meanwhile, average monthly temperatures ranged from near normal to 7.0 degrees F (3.9 degrees C) above normal in Colorado and Kansas. Many locations in Kansas ranked in the top 10 warmest Junes on record and set many daily high temperature records. Dodge City, Kansas had its 5th warmest June on record (period of record 1874-2011) with an average temperature of 79.8 degrees F (26.6 degrees C). The record, which was set in 1952, held at 81.7 degrees F (27.6 degrees C). Interestingly, Dodge City had 10 days this month in which the maximum temperature was 100 degrees F (37.8 degrees C) or greater. Typically, Dodge City has only 1.5 days at or above 100 degrees F (37.8 degrees C) in June. June 1953 held onto the record with 11 days. One of these particularly hot days was June 26th , when Dodge City tied for its highest maximum temperature of all time with 110 degrees F (43.3 degrees C). The only other time that the temperature had been that high was June 29, 1998.
The USDM had slight changes throughout the month of June. Hot and dry conditions caused an expansion of extreme drought (D4) in parts of south central Colorado. Exceptional drought conditions (D5) were also expanded northward into extreme south central Kansas. Since last month, abnormally dry conditions have also expanded to southwestern Colorado. Heavy rains allowed for some improvement in southeastern Kansas where abnormally dry conditions (D0) and moderate drought conditions (D1) were eliminated, and also in northwestern Kansas, where D1 and severe drought conditions (D2 were erased. Meanwhile, North Dakota, South Dakota, and Wyoming remained drought free, while only small portions of southeast and southwest Nebraska had D0 this month.
As summarized by the Western Regional Climate Center, June of 2011 brought unprecedented extremes of wet, dry, snow pack, and atmospheric humidity to the western United States. Precipitation was far above its usually low normal in central and northern California, and continued to be above normal especially in eastern Montana. Other wet pockets were found in the northern Great Basin and the Wasatch. Even with a rainless month in the desert, preliminary figures show that California experienced its statewide wettest June on record (1895+). At San Francisco downtown, the month was the 2nd wettest June (behind 1884) in a record that begins in July 1849. The southern part of the region was significantly drier than its meager normal, where preliminary figures show that New Mexico experienced its driest June since 1895. The station at Carlsbad, New Mexico reported no precipitation for the 223 days preceding June 2, received a scant 0.01 inch (0.2 mm) on that day, and then no rain for the rest of June. Extremely dry and windy conditions fanned numerous wildfires in Arizona. The Wallow fire began on May 9th near Alpine, Arizona, and eventually erupted into the largest fire in Arizona history. The fire eventually spilled over into New Mexico. The Horseshoe 2 fire in Southeast Arizona started on May 8th near Chiracahua National Monument and had burned 223,000 acres (90,000 ha) until its containment on June 25th. The Las Conchas fire near Los Alamos, New Mexico began June 26th and quickly spread to over 103,000 acres (42,000 ha) by the end of the month.
June 27: Extremely Dry Air, Las Vegas, Nevada. Las Vegas recorded a temperature of 107 F (41.7 C) and a dew point temperature of -22 F (-30 C) late in the afternoon, for a dew point depression record of 129 degrees F (53.9 C) and relative humidity of 0.6 percent. This is the driest air ever recorded in this desert city, and may be the driest recorded at any climate station in United States history. Death Valley may have exceeded this low humidity, but only sporadic atmospheric moisture measurements exist for that location.
Temperatures were cooler than normal throughout the West except for the southeast portion of the region where temperatures were slightly to well above normal. At Clayton, New Mexico, 2011 brought the warmest June on record at 75.9 degrees F (24.4 C), which was 6.0 degrees F (3.3 C) above average. The previous warmest June was just one year ago.
The cool temperatures of the month greatly reduced the melt rate of the deep snowpack that affected most mountain locations outside of Arizona and New Mexico. This has significantly extended the snowmelt season, and the associated streamflow runoff season, far into the summer, with record late runoff, and floods exceeding the flood of record in many small basins in Utah and Colorado. Heavy precipitation combined with deep snow and cool temperatures led to melted snow and rain producing record releases from Fort Peck Reservoir in Montana, by far the greatest flows on the Missouri River since the dam was closed off in 1937.
Upper Colorado River Basin: As reported by the Colorado Climate Center, the June 28th NIDIS (National Integrated Drought Information System) assessment for the Upper Colorado River Basin (UCRB) indicated that, for the month of June, much of the northern portions of the UCRB received over half an inch to over 2 inches of precipitation, while the Four Corners was the driest region of the basin, receiving less than a tenth of an inch of moisture for the month. Northeastern and southeastern Colorado had 1 to 4 inches of accumulation for June. The San Luis Valley remained dry for the month, receiving less than a tenth of an inch of precipitation.
The majority of the SNOTEL sites in the UCRB reported very high (and in many cases, record high) percentile rankings for water-year-to-date (WYTD) precipitation. After a near record season high for snowpack in the UCRB, the majority of the SNOTEL sites have now completely melted their accumulated snowpack for the season. Most of the sites with significant remaining snowpack were located in the higher elevations of the Duchesne River basin (Lakefork Basin still had 25 inches of snow water equivalent) and near the upper reaches of the Colorado and Yampa Rivers (the Tower site still had about 40 inches of snow water equivalent). As of June 26th, about 97 percent of the USGS streamgages in the UCRB recorded normal (25th - 75th percentile) or above normal 7-day average streamflows with 63 percent of the gages recording flows above the 75th percentile.
Soil moisture conditions remained poor for the San Luis Valley. Soil moisture was above average along the Wasatch range in Utah, in the northern Colorado mountains, and in northeast Colorado. All of the major reservoirs in the UCRB experienced rapid storage increases in June. Daily inflows into Flaming Gorge, Blue Mesa, and Lake Powell were all well above their averages for this time of year. Inflows into Navajo dipped below their average for this time of year. Lake Powell saw large increases in volume and was at 80 percent of average at the end of June. It is projected that Lake Powell's elevation will continue to rise through late July, with projected elevation levels being the highest they've been since October 2001.
Pacific Islands: According to reports from National Weather Service offices, the Pacific ENSO Applications Climate Center (PEAC), and partners, conditions varied across the Pacific Islands.
Near to below normal precipitation fell during the past 30 days in the Hawaiian Island drought areas. The effects of spring rainfall continued to produce improvements in drought conditions over leeward portions of the Big Island and Maui County. This improvement trend was expected to end as drier and warmer conditions take hold during the heart of the 2011 dry season. During the month of June, a pocket of severe drought, or D2 category conditions on the USDM map, improved to moderate drought, or D1 conditions over the Pohakuloa area of the Big Island. However, severe drought persisted over the Kawaihae area of the south Kohala district. Improvements also occurred along the leeward slopes of Mauna Loa where a large swath of moderate drought was removed. Moderate drought continued over the leeward slopes of Maui from Lahaina to Mkena and over the western third of Mlokai. Kauai and Oahu remained drought-free.
Some drought impacts in Hawaii include the following:
- On Oahu, there were no drought impacts to report. The water supply in the Waimanalo reservoir remained well above drought level. However, the State of Hawaii Department of Agriculture was maintaining a voluntary 10 percent cutback in irrigation water use as a precaution.
- On Molokai, the State of Hawaii Department of Agriculture has kept in place the mandatory 30 percent cutback in irrigation water consumption.
- On Maui, by May, pastures and general vegetation from Kaonoulu to Kamaole near Kihei recovered enough to support cattle ranching operations. Dryness persisted over the leeward slopes and conditions may worsen heading into the heart of the dry season. There has been an increase in reports of axis deer encroachments into developed areas near Wailea due to forage degradation in the normal range lands. Water supply levels remained sufficient for upcountry Maui. However, as a precaution, the Maui County department of water supply continued to request a 5 percent reduction in water use by upcountry residents. A 10 percent reduction in water use by central and south Maui residents also remained in effect.
- On the Big Island, pastures and general vegetation conditions improved in early June but no additional improvements were reported during the last half of the month. In fact, the most recent reports indicated a drying trend over portions of the leeward Big Island slopes especially in the southern Kau district and lower slopes of the south Kohala district.
On other Pacific Islands, drought conditions effectively ended as the La Niña pattern across the equatorial Pacific transitioned to ENSO neutral and tropical rains returned in earnest. As seen in the table below, rainfall across the western Pacific has been highly variable from month to month. All stations had near to much above normal rainfall during June, although long-term (September 2010-June 2011) deficits remained at a few of the islands.
|Station Name||Sept. 2010||Oct. 2010||Nov. 2010||Dec. 2010||Jan. 2011||Feb. 2011||Mar. 2011||Apr. 2011||May 2011||Jun 2011||Sep. 2010-June 2011|
State/Regional/National Moisture Status
A detailed review of drought and moisture conditions is available for all contiguous U.S. states, the nine standard regions, and the nation (contiguous U.S.):
|northeast u. s.||east north central u. s.||central u. s.|
|southeast u. s.||west north central u. s.||south u. s.|
|southwest u. s.||northwest u. s.||west u. s.|
|Contiguous United States|
- Palmer Drought Indices
- Standardized Precipitation Index
- long-term (36 to 60 month) percent of normal precipitation maps
- airport station percent of normal precipitation maps
- statewide precipitation rank maps
- Cooperative station percent of normal precipitation maps
- percent of average maps for the SNOTEL stations in the western mountains provided by the Western Regional Climate Center
- satellite-based observations of vegetative health
- National Weather Service model calculations of soil moisture, runoff, and evaporation
- National Weather Service model calculations of soil moisture using the Leaky Bucket Model
- Midwest Regional Climate Center model calculations of soil moisture
- topsoil moisture conditions observed by the USDA and mapped by the Climate Prediction Center
- pasture and range land conditions observed by the USDA and mapped by the Climate Prediction Center
- streamflow maps maintained by the USGS
Contacts & Questions