Drought - March 2013
NCDC will transition to the nClimDiv dataset on Thursday, March 13, 2014. This is coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.
Please note that the values presented in this report are based on preliminary data. They will change when the final data are processed, but will not be replaced on these pages.
National Drought Overview
Detailed Drought Discussion
The polar jet stream (which marks the edge of the circumpolar vortex and the boundary between the cold polar air masses to the north and the warmer sub-tropical air masses to the south) was well entrenched over the eastern United States during March 2013, funnelling cold air masses into the country east of the Rockies while keeping the western U.S. generally warmer than normal. Weather systems moving in the very active jet stream flow combined with the frigid air to produce abundant snowfall in some areas east of the Rockies. These snowstorms, and rain from other systems, shrank drought areas in the Midwest and Southeast, but only a few weather systems moved through the upper-level ridge over the western U.S., resulting in a drier-than-normal month for much of the West. When the temperature and precipitation are averaged across the country for the entire month, March 2013 ranked as the 43rd coolest and fifth driest March in the 119-year record. The March precipitation helped reduce the moderate-to-exceptional national drought footprint from 54.2 percent at the end of February to 51.9 percent at the end of March. But, according to the Palmer Drought Index, which goes back to the beginning of the 20th century, 48.7 percent of the contiguous U.S. was in moderate to extreme drought at the end of March, an increase of about 10 percent compared to last month due to the fifth driest March nationwide.
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 stretching from the West, across the Northern and Southern Plains, into the Upper Midwest, with the most intense drought centered in the Plains states;
- an area of moderate to severe drought in the Southeast; and
- much of Hawaii, where moderate to extreme (D3) drought persisted.
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.
Used together, the Palmer Z Index and PHDI maps show that March short-term dry conditions occurred over long-term dry conditions that existed at the end of February across much of the West and parts of the Plains, which contributed to the expanded national drought area as measured by the Palmer metric. Short-term dry conditions occurred over long-term wet conditions in the Lower Mississippi Valley, and short-term dry conditions occurred over parts of the lower Great Lakes, Northeast, and coastal North Carolina where long-term conditions were generally neutral.
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.
The 1-month SPI map shows four distinct dry areas — the West, the South, the lower Great Lakes to Northeast, and coastal North Carolina — as well as an unusually moist area in the Upper Mississippi Valley. The dryness in the Northeast and especially the West has been very pronounced for the last 2 to 3 months, while much of the Mississippi Valley and Great Lakes have seen wet conditions at 2 to 6 months. Parts of the West show up as dry on the 6- to 24-month SPI maps, while the Northeast transitions to wet conditions by 24 months. Recent (1- to 3-month SPI) near-normal precipitation has helped conditions in the Central Great Plains, but dryness shows up at 6 to 24 months and is especially acute at 9 to 12 months. Recent beneficial rains have made much of the Southeast wet at 2 to 12 months, but long-term dryness is still evident at 24 months.
Agricultural, Hydrological, and Meteorological Indices and Impacts
Drought conditions were reflected in numerous agricultural, hydrological, and other meteorological indicators, both observed and modeled.
According to the U.S. Department of Agriculture (USDA), as of April 2, 56 percent of winter wheat, 51 percent of hay, and 62 percent of cattle were in drought. These percentages are less than the corresponding percentages from a month ago.
- NOAA Climate Prediction Center (CPC) modeled soil moisture anomalies and percentiles for the end of the month, and soil moisture anomaly change compared to previous month;
- CPC's Leaky Bucket model soil moisture percentiles;
- NLDAS (North American Land Data Assimilation System) modeled soil moisture percentiles for the top soil layer and total soil layer;
- VIC (University of Washington Variable Infiltration Capacity macroscale hydrologic model) modeled soil moisture percentiles, and soil moisture percentile change compared to previous month;
- Vegetation Drought Response Index (VegDRI);
- the NOAA/NESDIS satellite-based Vegetation Health Index (VHI);
- USGS observed streamflow percentiles;
- VIC 1-, 2-, 3-, and 6-month runoff percentiles;
- NLDAS model runoff anomalies and percentiles;
- NLDAS modeled streamflow anomalies and percentiles;
- USGS groundwater observations (real-time network, climate response network, total active network);
- USDA snow pack and snow water content observations for the West (SNOTEL station percentiles, SNOTEL station percent of normal, SNOTEL basin percent of normal and percent of average) and Alaska SNOTEL station and basin percent of normal;
- VIC modeled snow water content percentile;
- NOAA/Rutgers University Global Snow Lab satellite-observed snow cover anomalies;
- USDA statewide reservoir storage as percent of capacity (with average depicted);
- monthly total precipitation (plotted by the USGS, NOAA National Weather Service [NWS], and NOAA High Plains Regional Climate Center [HPRCC]);
- monthly percent of normal precipitation and precipitation percentiles (NWS, HPRCC station observations, West SNOTEL and ACIS stations, Alaska SNOTEL stations, Leaky Bucket model) and precipitation anomalies (CPC);
- NCDC monthly statewide precipitation ranks;
- USGS 30-day number of days with precipitation and maximum number of consecutive dry days;
- water-year-to-date (October-present) percent of normal precipitation (NWS, HPRCC station observations, West SNOTEL and ACIS stations, West basins, Alaska stations) and precipitation percentiles (West SNOTEL stations);
- monthly temperature departures from normal (CPC, HPRCC) and temperature percentiles (CPC, Leaky Bucket);
- NCDC monthly standardized temperature departures and statewide temperature ranks; and
- number of record warm daily low temperatures, record daily high temperatures, record daily low temperatures, and record cool daily high temperatures, set during the month (from NCDC's daily records analysis).
Hawaii: March 2013 was drier than normal for most Hawaiian stations. The above-normal February precipitation on the windward side of the southeastern islands still shows up at 2 and 3 months, but a drier-than-normal pattern dominates at longer time scales (6, 12, 24, and 36 months). Streamflow on the Big Island averaged below normal. The percent of the state experiencing moderate to extreme drought area fell slightly from 45 percent last month to 43 percent this month.
Alaska: The precipitation pattern in March 2013 was mixed, but overall the state experienced its 31st wettest March in the 1918-2013 record. March 2013 temperatures were mostly below the 1981-2010 normal, but ranked mid-range (48th warmest) in the longer 1918-2013 record. The precipitation pattern was mixed at longer time scales (2, 3, 6, 12, 24, and 36 months). Abnormal dryness covers about half of the state on the USDM map with a spot of moderate drought continuing in the Koyukuk Basin where the water content of the snow pack and water-year-to-date (October-present) precipitation were low.
Puerto Rico: Above-normal precipitation fell over central and eastern parts of Puerto Rico during March, but the west end of the island was drier than normal. Much of the island has had below-normal rainfall for the last 2 to especially 3 months. But the area with the driest anomalies shifts to the southeast at longer time scales (last 6 months). An area of D0 (abnormally dry) stretched across the island from the west end to the southeast on the April 2 USDM map.
On a statewide basis, March 2013 ranked in the top ten driest category for two states (Louisiana and Wyoming) and twelfth driest for two others (Texas and New York). Twenty-five other states ranked in their driest third of the historical record. Dryness for the year to date was centered in the West and Northeast, where 19 states (along with Florida) ranked in the driest third of the historical record — six of which (California, Idaho, Oregon, Nevada, Utah, and Wyoming) had a top ten driest January-March. In fact, 2013 had the driest January-March in the 119-year record for California.
The last six months were drier than normal for 12 states in the West and Plains plus Florida and three states in New England. In spite of an above-normal start to the wet season (October-December 2012), the last three months (January-March 2013) have been so dry as to rank California twelfth driest for the wet season (October 2012-March 2013). The last twelve months were the driest April-March on record for Nebraska and Wyoming, with four other states (Colorado, New Mexico, Kansas, and Oklahoma) ranking in the top ten category, and 14 other states (stretching from the west coast to Ohio Valley, plus Delaware) ranking in the driest third of the historical record for April-March. It was so dry in Nebraska that the state was driest for all seasons from 7 months (September-March) to 12 months (April-March).
Percent area of the Western U.S. in moderate to extreme drought, January 1900 to present, based on the Palmer Drought Index.
March 2013 was much drier than normal for most of the West, with the last three months having record dry conditions, especially along the coastal states (as noted above). Water year-to-date (October-present) precipitation was near- to above-normal in the northern regions and below- to much-below normal in the southern areas of the West — especially in the Central and Southern Rockies, as seen in high elevation (SNOTEL) station percentiles and basin averages, and across the Southwest, Southern California, and Great Basin, as seen in low elevation station observations. Snow pack water content (station percentiles and basin percent of normal) was much below-normal in the Central to Southern Rockies, Great Basin, and Sierra Nevada, and below normal across parts of the Northern Rockies and Pacific Northwest. Reservoir storage was below average in several states in the Southwest (Arizona, Colorado, New Mexico) and Great Basin to Northwest (Nevada, Oregon), but near to above average in the other states. Integrated satellite and ground observations of vegetation condition (VegDRI) indicated widespread stress on vegetation across the West. According to the USDM, 63.5 percent of the West was experiencing moderate to exceptional drought at the end of March, slightly less than last month. The Palmer Drought Index percent area statistic was 72.2 percent, an increase of about 21.6 percent compared to last month.
March 2013 was the 28th driest March in the 1895-2013 record for the Primary Hard Red Winter Wheat agricultural belt. Rain and snow during the first couple months of 2013 helped balance out the dryness, but this is the dry season. Below-normal precipitation during earlier months, combined with the January-March precipitation, gave the growing season (October-April) a rank of 27th driest so far (through March). Temperatures for the period (October-March) ranked 42nd warmest. The PHDI continued at severe drought levels, regionwide.
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 described by the High Plains Regional Climate Center, a persistent and strongly negative phase of the Arctic Oscillation kept temperatures well below normal across the region. Precipitation varied across the region this month. Generally, precipitation was below normal except for northern North Dakota, northeastern Colorado, and pockets of northwestern Wyoming and north-central and eastern Nebraska. Other areas were quite dry and received less than 50 percent of normal precipitation. These areas included central and northern South Dakota, the panhandle and central parts of Nebraska, southern and eastern Wyoming, southern Colorado, and a swath from western Kansas through southeast Nebraska. The varied precipitation allowed for top 10 rankings on both the dry and wet sides. Even with the start of spring, snowpack continued to be of concern in the Rockies and also North Dakota. Unfortunately, snowpack in the Rockies continued to be lower than average. As of April 1st, the statewide Colorado snowpack was only 73 percent of average, down from 75 percent at the end of last month. Similarly, the statewide Wyoming snowpack was down 2 percent to 82 percent of average. On the opposite end of the spectrum, there is a chance for flooding later in the season in the northern areas of the region. Even though most of the region was still dealing with the ongoing drought, northern areas of North Dakota have received above normal precipitation which has led to a solid snowpack with high water content.
Just like February, there were only slight changes to the USDM over the past month. Approximately 91 percent of the region was still in moderate (D1) to exceptional (D4) drought - exactly the same percentage as the end of last month. Precipitation was spotty, which allowed for only slight improvements. Some D4 areas in southern South Dakota, northeastern Colorado, northwestern Kansas, and small portions of Nebraska had a one-category improvement which reduced the D4 coverage from 27 percent to 22 percent. Small one-category improvements were also made in eastern Kansas and southwestern Colorado. Unfortunately, conditions worsened in northwestern South Dakota where extreme drought conditions (D3) expanded. Even with some slight improvements, Nebraska remained the hardest hit state with 76 percent of the state in the D4 designation.
As explained by the Southern Regional Climate Center, monthly precipitation totals were generally below normal throughout most of the Southern region and, with the exception of Texas and Oklahoma, March proved to be a much cooler month than expected. Texas had an extremely dry month, with a majority of stations receiving less than half the expected amounts. The driest parts of the region occurred in western and southern Texas, and along the Gulf Coast of the Southern region, where most stations reported less than twenty-five percent of normal. In the western central counties of Texas, many stations averaged less than five percent of normal precipitation for the month. The state average precipitation totals for the month are as follows: Arkansas averaged 3.57 inches (90.68 mm), Louisiana averaged 1.46 inches (37.08 mm), Mississippi averaged 4.09 inches (103.89 mm), Oklahoma averaged 1.22 inches (30.99 mm), Tennessee averaged 5.05 inches (128.26 mm), and Texas averaged 0.71 inches (18.03 mm). For Louisiana, it was the fourth driest March on record (1895-2013), while Texas reported its twelfth driest March on record (1895-2013). Oklahoma experienced its twenty-third driest March on record (1895-2013), while for Mississippi, it was their twenty-seventh driest March on record (1895-2013). All other state rankings fell in the middle two quartiles.
Below normal precipitation totals in Texas caused some drought conditions in the southern portions to worsen, but in general, drought conditions in the Southern region have not changed significantly over the past month. As was the case last month, Louisiana, Mississippi and Tennessee remain drought free. Though there is still some moderate drought in western Arkansas, the bulk of the severe to extreme drought conditions are still localized to Texas and Oklahoma, with little changes to total areal extent. The driest portions of west Texas, particularly near and west of Lubbock, saw several high wind days that caused dust storms. Dry grasslands, driven by high winds from frequent frontal passages, are leading to growing fire concerns, as several wildfires have burned over 750 acres, such that $161 million dollars for fuel removal and wildfire control is in the process of passing through the state legislature (Information provided by the Texas State Climate Office).
In Texas, new agricultural problems are cropping up as well. The latest frontal system brought below freezing temperatures, causing fears that wheat crops could be damaged. High rainfall deficits have farmers rethinking plans to grow cotton, reducing the estimated planting numbers by 25 percent. Feed prices continue to ruse, causing ranchers in west and south Texas to reduce herd numbers. By the end of March, herd populations were the lowest seen since 1967, causing a meat processing plant in San Angelo, costing 200 jobs (Information provided by the Texas State Climate Office).
As summarized by the Midwest Regional Climate Center, March temperatures were well below normal across the Midwest averaging 30.4 degrees F (-0.8 degrees C) or 14th coolest dating back to 1895. Temperatures were not particularly extreme, but rather just consistently cooler than normal for most of the month. This was a striking contrast to the record warmth in March 2012 when all nine states recorded their warmest March dating back to 1895, some breaking old statewide records by several degrees.
March precipitation was more varied with Indiana recording a statewide total more than an inch (25 mm) below normal while three states recorded above normal totals. Wetter than normal conditions were common in the western and southern parts of the Midwest especially in northern Minnesota and southern Missouri where totals exceeded 150 percent of normal. Drier conditions were generally in the northeastern Midwest including a large area with less than 50 percent of normal precipitation in a large part of Lower Michigan and northern sections of Indiana and Ohio. Snow totals were above average for most of the Midwest with some locations from Minnesota to Illinois to Ohio topping normal by ten inches (25 cm) or more. The snows came from several systems spread throughout the month.
Drought conditions improved according to the USDM with the area in drought dropping from over 46 percent of the Midwest on February 26th to just over 33 percent on March 26th. Areas in severe (23 to 20 percent) and extreme (8 to 6 percent) drought also dropped in the same time period. During March, Illinois joined Indiana, Ohio, and Kentucky as drought-free states. Missouri also saw a large decrease in drought during March. Michigan only had a tiny portion of the Upper Peninsula in drought. Minnesota, most of Iowa, and northwest Wisconsin had persistent drought. Ample snow pack and persistent cool temperatures have created the potential for severe flooding on the Red River on the western border of Minnesota. Frozen soils will likely lead to substantial runoff of melting snow rather than infiltration into the soils. The later than normal snow melt increases the chances of heavy rain falling on top of the remaining snow which can lead to enhanced run off.
As noted by the Southeast Regional Climate Center, precipitation was below average (50 to 90 percent of normal) across most of the Southeast in March, except across parts of the region that experienced severe storms, including northern Alabama, central Georgia and South Carolina, and northern Virginia. The driest locations in March were found across much of the Florida Peninsula and eastern North Carolina, where monthly precipitation totals were less than 50 percent of normal. Greenville, NC recorded its second driest March on record with 1.14 inches (28.9 mm) of precipitation (period of record: 1927-2013), while Miami, FL recorded just 0.81 inches (20.6 mm) for the month, which was more than 2 inches below normal. Monthly precipitation was variable across Puerto Rico, with above (below) average precipitation across the eastern (western) half of the island, while precipitation was generally above average across the U.S. Virgin Islands.
Despite below-average precipitation across much of the region, drought conditions continued to improve in March, with as much as a 10 percent reduction in the area covered by drought between the beginning and end of the month. Most notably, the areas of severe drought (D2) across Georgia and South Carolina were eliminated. In Georgia, this marked the first such occurrence since September 2010. Small improvements in drought conditions were also noted across eastern sections of South Carolina and much of the Florida Panhandle. In contrast, the warmer and drier weather that has persisted across the Florida Peninsula for the past few months resulted in an expansion and intensification of drought, particularly across the northeastern part of the Peninsula. A wildfire in Hopkins Prairie west of Daytona Beach grew to nearly 2000 acres and destroyed as many as 10 homes in Marion County. In terms of agriculture, cold weather and heavy rain at the beginning of the month damaged as much as a quarter of the sweet corn crop and hampered the growth of green beans across South Florida. Additional cold spells and generally dry weather forced citrus growers to begin irrigating multiple times a week and slowed the growth of several vegetable crops. By the end of the month, many farmers in Florida were assessing crop damage from the cold weather, as well as from the hail and high winds associated with severe thunderstorms that raked the area.
Monthly mean temperatures in March were below average across the Southeast region. The greatest departures were found across parts of western Florida, northern sections of Alabama and South Carolina, and central portions of Georgia and North Carolina, where monthly temperatures were 6 to 7 degrees F (3.3 to 3.9 degrees C) below average. Monthly temperatures were also slightly below average across the U.S. Virgin Islands. Nearly 100 stations across the Southeast recorded one of their top 3 coldest Marchs on record. For over 20 locations in the region, the monthly mean temperature in March was lower than the mean winter season (December-February) temperature. In some cases, this was the first such occurrence in over 50 years (e.g. Miami, FL, Columbia, SC, and Raleigh-Durham, NC). For the month, over 350 daily minimum and over 400 daily low maximum temperature records were tied or broken across the Southeast.
As explained by the Northeast Regional Climate Center, dry conditions lingered into March across the Northeast. Receiving 2.39 inches (60.7 mm) of precipitation, 68 percent of normal, the region had its 17th driest March on record. All states were drier than normal with departures ranging from 51 percent of normal in Rhode Island to 80 percent of normal in West Virginia, Maryland, and Delaware. Four of the twelve Northeast states ranked March 2013 among their top 22 driest: New York, 12th; Pennsylvania, 13th; Connecticut, 21st; and New Hampshire, 22nd. Cooler than normal temperatures prevailed for nine of the twelve Northeast states during March. With an average temperature of 33.3 degrees F (0.7 degrees C), it was 1.3 degrees F (0.7 degrees C) below average in the Northeast.
Abnormally dry (D0) conditions persisted through March in northeastern New York and along the Vermont-New Hampshire border. According to the USDM issued on April 2, 2013, "parts of the lower Northeast have received 2 to 4 inches less precipitation than normal since the beginning of the year, so abnormal dryness was expanded into these regions." The regions referred to include portions of southern New York, a large swath of Pennsylvania, portions of western New Jersey, and part of one county in Connecticut.
As summarized by the Western Regional Climate Center, March was drier than normal for much of the West, especially northern California, northern Nevada, Oregon, and eastern New Mexico. The northern tier of the West was slightly cooler than normal while many locations in the southern Great Basin and Desert Southwest saw March average temperatures among the highest on record. High pressure aloft over California kept storm tracks to the north and temperatures around 5 F (2.8 C) above normal in the southern Great Basin and Desert Southwest. Cooler than normal weather was observed this month in the inland Northwest.
After a dry January and February, sparse precipitation continued in March over much of the West. In the central Sierra, Tahoe City, California recorded its driest January-February-March in a 103-year record at 2.68 in (68 mm), only 16% of the normal 16.3 in (414 mm). Elsewhere in northern California, Ukiah also recorded its driest start to the year at 4.05 in (103 mm), 15.02 in (382 mm) below normal. Only 6.99 in (178 mm) of precipitation fell in downtown Portland, Oregon since the first of the year. This was the driest such period in a 123-year record and 47% of normal. Many other locations throughout Oregon, Nevada, and California recorded one of their 10 lowest January-February-March precipitation totals on record. A winter storm on the 8th and 9th brought precipitation to the Southwest (especially CA) and snow accumulations up to 24 in (610 mm) in mountainous areas. This was the only precipitation of the month for much of this region, but enough to keep many locations above 50% of normal. Colorado's Front Range received beneficial precipitation this month as well. Boulder recorded its driest March on record in 2012, while March 2013 fell just short of one of the top-10 snowiest on record at 23.5 in (59.7 cm).
The end of March is typically the peak snowpack for many locations in the West and an important date for anticipation of springtime runoff. Snow water content in the northern Cascades and northern Rockies was near normal to slightly above normal at month's end. To the south, snow water content in the Sierra Nevada, Utah's Wasatch and Uinta ranges, the southern Rockies, and Arizona's Mogollon Rim region stood at less than 75% or less of normal. This is the second winter in a row these areas have recorded below normal snow water equivalent in their snowpack at the end of March, raising concerns about water resources.
According to the USDM, severe drought conditions continued for much of the West this month with over 80% of the West at least abnormally dry. Severe to exceptional drought continued for New Mexico, Colorado, and Wyoming and the region of severe drought expanded in northern Nevada. Abnormally dry conditions spread through eastern Oregon and southwestern Montana as well. Some drought relief was seen this month in northeastern Colorado.
As solar isolation increases in the Arctic with the changing of seasons, sea ice extent has begun to decline and locations along Alaska's North Slope are displaying above normal temperatures for March after being cooler than normal during December and January. Barrow reported an average -7.4 F (-21.9 C) for March, 5.3 F (2.9 C) over normal. A dramatic and rapid breakup of the thin pack ice of the Beaufort Sea north of Alaska took place over February and March. Temperatures elsewhere in the state were generally several degrees below normal. Near-normal precipitation fell throughout southern Alaska, though portions of the Interior and Southeast regions were below normal for the month. Further south, cool and stormy weather dominated in Hawaii. After 12 days of sub-80 F (26.7 C) highs, Honolulu hit 81 F (27.2 C) on March 22. This was the longest period of sub-80 F (26.7 C) highs since March 2-14, 2012.
Upper Colorado River Basin: As reported by the Colorado Climate Center, the April 2nd NIDIS (National Integrated Drought Information System) assessment for the Upper Colorado River Basin (UCRB) indicated that the majority of the UCRB received below average precipitation during March. Some areas of southwest Wyoming, eastern Utah and the northern and central Colorado mountains received near to slightly above average precipitation for the month. Sweetwater County, WY, western CO and the Colorado River valley in eastern UT were much drier, receiving less than 50% of average precipitation for the month. East of the basin, parts of the CO Front Range and northeast CO received above average precipitation while far northern CO and most of the Arkansas valley received below average precipitation last month. Water-year-to-date SNOTEL precipitation percentiles in the UCRB are below the median throughout the entire basin. Accumulated snowpack is currently less than normal across the entire UCRB, and most of the sub-basins saw large decreases in percents of normal over the last week. Sub-basins in western CO range are between 72% and 81% of normal snowpack. Eastern UT basins are under 70% of normal while snowpack in the sub-basins of northern UT and southwest WY range between 70% and 80% of normal.
As of March 31st, about 21% of the USGS streamgages in the UCRB recorded normal (25th - 75th percentile) to above normal 7-day average streamflows, a decrease from 49% last week. About 57% percent of the gages in the basin are recording much below normal or low (i.e. lowest on record) streamflows, and only 1 gage is reporting above normal flows (and that is solely due to reservoir releases above that gage). Lower flows are a combination of extended drought and colder temperatures. Last month, most of the major reservoirs in the UCRB saw volume decreases. Flaming Gorge and Blue Mesa saw slight volume increases, while Green Mountain has begun to see volume increases in the past couple of weeks. Lake Granby decreased by a larger percent than is normal. For the beginning of April, Flaming Gorge and Green Mountain are near average while the remaining reservoirs are all below average, ranging from 47% of average (Lake Granby) to 83% of average (Blue Mesa).
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.
As noted by the National Weather Service office in Honolulu, several cold fronts affected the state of Hawaii during March but most of the associated rainfall occurred over areas not under drought conditions. The main exception is Molokai which received significant rainfall that enabled continued improvements through the month. In the west half of the island, most of the D2 area in the USDM map, which is the severe drought category, has improved to the D1 level, or moderate drought. Severe drought is currently limited to just the north central section of Molokai due to long-standing reservoir supply levels. Limited rainfall occurred in late March over the existing extreme drought areas, or the D3 category, on the Big Island and the island of Maui. Localized showers on the western side of the Pohakuloa region on the Big Island allowed for a small amount of improvement to the D2 level but the remaining D3 areas remained unchanged. On the lower Kona slopes of the Big Island, rainfall activity helped bring severe drought down to the moderate level. Drought is also in a slow retreat on Lanai where severe drought has been reduced to a small coverage over the southwest side of the island. Elsewhere, Kauai remains drought-free, though the lower south slope has been drier than normal and may slip back into drought soon. Oahu has just a small area of moderate drought, or D1 category conditions, over the leeward slopes of the Waianae range. Recent rainfall may have been sufficient to produce regrowth of pastures to show improvement in drought category.
Some drought impacts impacts in Hawaii include the following:
KAUAI. THERE ARE CURRENTLY NO DROUGHT AREAS ON KAUAI. OAHU. LATE MARCH RAINFALL OVER WEST OAHU MAY HAVE BEEN SUFFICIENT TO SUPPORT SIGNIFICANT REGROWTH OF PASTURES BUT IT IS TOO SOON TO TELL IF IT WAS ENOUGH TO REMOVE DROUGHT. MOLOKAI. WEST MOLOKAI CONTINUES TO SEE IMPROVING AGRICULTURE AND GENERAL VEGETATION CONDITIONS. SATELLITE-BASED VEGETATION HEALTH DATA SHOW ADDITIONAL IMPROVEMENTS OVER THE PAST MONTH. WATER LEVELS AT THE KUALAPUU RESERVOIR HAVE SLOWLY RISEN SINCE THE BEGINNING OF THE YEAR. WHILE THIS IS A POSITIVE SIGN...THE STATE OF HAWAII DEPARTMENT OF AGRICULTURE CONTINUES TO MAINTAIN A MANDATORY 30 PERCENT REDUCTION IN IRRIGATION WATER CONSUMPTION. LANAI. SATELLITE-BASED VEGETATION HEALTH DATA SHOW ADDITIONAL IMPROVEMENTS OVER THE PAST MONTH...ESPECIALLY OVER THE NORTHWESTERN PORTION OF THE ISLAND. MAUI. LEEWARD MAUI RECEIVED SOME RAINFALL BUT NO DATA HAVE BEEN RECEIVED SO FAR INDICATING THAT PASTURE CONDITIONS MARKEDLY IMPROVED. PASTURES IN THE EXISTING DROUGHT AREAS WERE DESTOCKED MANY MONTHS AGO. THE MAUI COUNTY DEPARTMENT OF WATER SUPPLY CONTINUED ITS LONG STANDING REQUEST FOR A 5 PERCENT REDUCTION IN WATER USE FOR UPCOUNTRY RESIDENTS. THE REQUEST FOR A 10 PERCENT REDUCTION IN WATER USE BY CENTRAL AND SOUTH MAUI RESIDENTS ALSO REMAINED IN EFFECT. BIG ISLAND. RAINFALL DATA AND FIELD REPORTS INDICATE THAT THE AGRICULTURAL AND GENERAL VEGETATION CONDITIONS HAVE IMPROVED IN THE LOWER ELEVATIONS OF THE NORTH AND SOUTH KONA DISTRICTS AS WELL AS THE WESTERN END OF THE POHAKULOA REGION.
On other Pacific Islands (maps — Micronesia, Marshall Islands, basinwide), March was drier than normal at Majuro and Pago Pago, and much drier than normal at Koror, Pohnpei, Kosrae, and Kwajalein. March rainfall amounts were below 4 inches at Kwajalein, Saipan, and Guam and below 8 inches at Koror, Yap, and Majuro. (This is the dry season for several of these stations, so even low rainfall amounts may show up as high percent of normals [for example, Saipan, Guam, Yap].) Majuro has been below normal for 9 of the last 12 months, Kwajalein and Pohnpei for 8 of the last 12 months. Twelve-month rainfall totals (April 2012-March 2013) for Koror, Kwajalein, Majuro, and Pohnpei are below normal.
According to NWS reports, parts of the northern Marshall Islands have become critically dry and parts of Yap state have become very dry during March and into early April. Serious drought conditions are occurring for atolls of the Marshall Islands north of Majuro, including Ebeye, Enewetak, Wotje, Ujae, Maloelap, Wotho, Utirik and other islands and atolls north of 8 degrees north. Conditions have improved somewhat across Chuuk state and from Majuro southward, and drought conditions are no longer expected there.
Impacts: On Majuro, dry-season type rain showers have recently helped water conditions, increasing the Majuro reservoir to a little over half full with 18.468 million gallons by early April. Despite the increased rainfall, water conservation measures are still recommended for the next month or so as week-long periods of dry weather are still possible. For atolls north of Majuro, stringent conservation measures are needed to avoid the depletion of wells and catchments. The mayor of Wotje indicates that the well-water on Wotje has become too salty to drink and that catchments are nearly empty. Water augmentation measures are urgently needed there.
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