Drought - October 2016


NCEI added Alaska climate divisions to its nClimDiv dataset on Friday, March 6, 2015, coincident with the release of the February 2015 monthly monitoring report. For more information on this data, please visit the Alaska Climate Divisions FAQ.

Issued 14 November 2016
Contents Of This Report:
Map showing Palmer Z Index
Percent Area of U.S. in Moderate to Extreme Drought, Jan 1996 to present
Connecticut statewide precipitation, November-October, 1895-2016

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

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Detailed Drought Discussion


Overview


The U.S. Drought Monitor drought map valid November 1, 2016
The U.S. Drought Monitor drought map valid November 1, 2016.

During October 2016, numerous troughs and cutoff lows moving in the jet stream flow directed cold fronts and moisture from the Pacific into the northwestern portions of the CONUS. The resulting wetter-than-normal month helped contract drought and abnormal dryness in the Pacific Northwest, Northern California, and Northern Rockies. The fronts and surface lows dried out as they crossed the Rockies. This drying effect, plus the frequent occurrence of ridges in the upper-level flow, resulted in a drier-than-normal month across much of the Plains. The fronts and lows were rejuvenated as they crossed over the Great Lakes, where near- to above-normal precipitation fell, contracting drought in western parts of the Northeast. Rains from Hurricane Matthew inundated parts of the coastal Southeast, but descending air from the North Atlantic (Bermuda) High and ridges in the jet stream flow kept precipitation below normal across the Southwest to much of the Southeast. The continued dry weather, coupled with abnormally high temperatures which enhanced evapotranspiration, expanded and intensified drought and abnormal dryness in the Central Rockies to adjacent Plains, parts of the Northeast, and especially in the Southern Plains to Southeast. When precipitation is integrated across the CONUS, October 2016 ranked as the 49th wettest October in the 1895-2016 record. October was drier than normal over most of Alaska, resulting in the driest October, statewide, in the 1925-2016 record. It was drier than normal across most of Hawaii while most of Puerto Rico was wetter than normal. Drought and abnormal dryness were minimal across Alaska, Hawaii, and Puerto Rico. Drought expansion was greater than contraction, so the USDM-based national moderate-to-exceptional drought footprint increased across the CONUS from 19.4 percent at the end of September to 26.8 percent at the end of October (from 16.2 percent to 22.4 percent for all of the U.S.). According to the Palmer Drought Index, which goes back to the beginning of the 20th century, about 15.2 percent of the CONUS was in moderate to extreme drought at the end of October, a decrease from last month's 20.6 percent.

Percent area of the CONUS in moderate to exceptional drought, January 4, 2000 to present, based on the U.S. Drought Monitor
Percent area of the CONUS in moderate to exceptional drought, January 4, 2000 to present, based on the U.S. Drought Monitor.


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. While both the PDSI and PHDI indices show long-term moisture conditions, the PDSI depicts meteorological drought while the PHDI depicts hydrological drought. The PDSI map shows less severe and extensive drought in parts of the West than the PHDI map because the meteorological conditions that produce drought and wet spell conditions are not as long-lasting as the hydrological impacts.

Palmer Z Index map Palmer Hydrological Drought Index map

Used together, the Palmer Z Index and PHDI maps show that short-term dry conditions occurred across the Southwest to Central and Southern Plains, the Southeast, and parts of the Northeast. This short-term dryness expanded or intensified long-term dry conditions in October compared to September in the Southwest, Southeast, and Northeast, and reduced the intensity of long-term wet conditions in the Southern to Central Plains. Short-term wet conditions reduced long-term drought conditions in the Pacific Northwest to Northern Rockies and parts of the Northeast.



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.

1-month Standardized Precipitation Index 2-month Standardized Precipitation Index 3-month Standardized Precipitation Index

6-month Standardized Precipitation Index

The SPI maps illustrate how moisture conditions have varied considerably through time and space over the last two years. Dryness dominates the Southeast and parts of the Northeast for the last 1 to 9 months and parts of the Central Rockies to adjacent Plains for the last 1 to 6 months. Much of the Southwest is dry at the 1-month time scale, while parts of the Southwest and Southern California show up as dry at the 2- to 24-month time scales. Wet conditions are evident in the Northwest, along the coast from the Southeast to Mid-Atlantic, and in the Upper Midwest at all time scales, and dominate the Southern Plains to Ohio Valley at the 3- to 24-month time scales.


9-month Standardized Precipitation Index 12-month Standardized Precipitation Index 24-month Standardized Precipitation Index



Standardized Precipitation Evapotranspiration Index


The SPI measures water supply (precipitation), while the SPEI (Standardized Precipitation Evapotranspiration Index) measures the combination of water supply (precipitation) and water demand (evapotranspiration as computed from temperature). Warmer temperatures tend to increase evapotranspiration, which generally makes droughts more intense.

1-month SPEI for current month
1-month SPEI for current month.
1-month SPI for current month
1-month SPI for current month.

State Month Precipi- tation
Rank
Tempera- ture
Rank
SPEI
Rank
SPI
Rank
Alabama October second driest sixth warmest worst second worst
Louisiana October fifth driest sixth warmest second worst fifth worst
Mississippi October eighth driest fifth warmest second worst eighth worst
New Mexico October 18th driest warmest second worst 22nd worst
Tennessee October seventh driest sixth warmest second worst seventh worst
Alabama Sep - Oct third driest fifth warmest worst third worst
Mississippi Sep - Oct ninth driest fourth warmest worst seventh worst
Tennessee Sep - Oct third driest third warmest second worst tied third worst

Temperatures were much warmer than normal across the States from the Rocky Mountains to the East Coast during October. The combination of these unusually warm temperatures and the lack of precipitation resulted in the 1-month SPEI map showing more severe drought conditions than the 1-month SPI map in the Southwest to Southeast. When the heat and dryness of the last two months is examined, the 2-month (September-October) SPEI map shows more severe drought conditions than the SPI map in the Southeast and Central Rockies. The warmest and 18th driest October, statewide, combined to give New Mexico the second most severe SPEI; this compares to the 22nd most severe SPI in the 1895-2016 record. For Alabama, the second driest October gave the state the second worst SPI, but the sixth warmest October resulted in the most severe SPEI on record. The ninth driest and fourth warmest September-October combined to give Mississippi the most severe 2-month SPEI for October, while the SPI ranked seventh most severe. Other examples of precipitation, temperature, SPEI, and SPI ranks for October and September-October can be found in the table to the right.

Warmer-than-average temperature anomalies for the last six months contributed to more severe drought on the 6-month SPEI map compared to the SPI map in parts of the West, Southeast, and Northeast where precipitation was below normal. Likewise for the last ten months (SPEI map vs. SPI map) and, for the Southwest and Northeast, for the last 12 months (SPEI map vs. SPI map). The second warmest and sixth driest November-October gave Connecticut the fifth most severe 12-month SPEI for October but only the 15th most severe SPI. Of particular interest is the steady increasing trend in temperatures for Connecticut over the last 50 years.

12-month SPEI for Connecticut, October, 1895-2016 November-October Statewide Temperatures for Connecticut, 1895-2016

Significant differences between the SPEI and SPI maps begin to appear in the West at the 24-month time frame (SPEI vs. SPI) and become increasingly significant at the 36-month (SPEI vs. SPI), 48-month (SPEI vs. SPI), 60-month (SPEI vs. SPI), and even 72-month (SPEI vs. SPI) time scales. This is due to persistent above-normal temperatures in the West for the last several years which have increased evapotranspiration and exacerbated drought conditions. Thirteen of the last 17 years (November-October periods) rank in the top 20 warmest category, with last year (November 2014-October 2015) being the warmest. Even with widespread near- to cooler-than-normal temperatures across the West in August, September, and October 2016, the November 2015-October 2016 12-month temperature still ranked as the seventh warmest on record.


36-month SPEI map 48-month SPEI map 60-month SPEI map

This is especially the case in California, where the last five November-October 12-month periods ranked in the top 14 warmest such periods for the state in the 1895-2016 record. The last five years cap a period of persistent unusual warmth which has lasted over three decades. The precipitation for the last 12 months gave California a statewide precipitation rank of 35th wettest (87th driest) for November 2015-October 2016. But the persistent dryness since 2000 still gave the state the driest SPI for the last 60 months, sixth driest for the last 48 months, and ninth driest for the last 72 months. When the temperature is factored in, California has had the most severe SPEI on record for the last 60 and 72 months, second most severe SPEI for the last 48 months, and third most severe SPEI for the last 36 months. Nearby Nevada tied for the second most severe SPEI for the last 60 months.

California statewide temperature, November-October, 1895-2016
California statewide temperature, November-October, 1895-2016.
California statewide 60-month SPEI for October, 1895-2016
California statewide 60-month SPEI for October, 1895-2016.



Regional Discussion


NOAA NLDAS soil moisture percentiles for October 2016
NOAA NLDAS soil moisture percentiles for October 2016.
USGS streamflow percentiles for October 2016
USGS streamflow percentiles for October 2016.



CONUS Agricultural & Hydrological Impacts:

The dry and warmer-than-normal weather of October exacerbated drought conditions in the South and East, while long-term drought continued in parts of the West. This is reflected in numerous agricultural, hydrological, and other meteorological indicators, both observed and modeled. The dry weather, with increased evapotranspiration, dried soils (USDA observations, SMOS satellite-based model, Leaky Bucket model, CPC model, NLDAS model, VIC model) and stressed vegetation (VegDRI and the NOAA satellite-based VHI, stressed vegetation index, and drought risk index) (Crop Moisture Index [CMI] for weeks 1, 2, 3, 4). Where the dry conditions have been continuing for several months, hydrological conditions such as streamflow and groundwater supplies were reduced, as well as reservoir levels in the West. The dry conditions during October are reflected in number of rain days and maximum number of consecutive dry days as well as total precipitation. On a national scale, as of November 1st, 25 percent of the nation's cattle inventory, 27 percent of the nation's hay, 15 percent of soybean production, 15 percent of winter wheat production, and 9 percent of corn production were in drought. These percentages are increases compared to the values for the end of September. According to October 31st U.S. Department of Agriculture (USDA) reports, 17 percent of the cotton crop, 9 percent of the winter wheat crop, and 23 percent of the pasture and rangeland were rated in poor to very poor condition, which are increases compared to the end of September. And 29 percent of the nation's topsoil moisture and 29 percent of the subsoil moisture were rated short to very short (dry to very dry), both also increases compared to last month. On a regional basis, conditions varied and were more extreme.

Drought conditions at the end of the month, as depicted on the November 1st USDM map, included the following CONUS core drought and abnormally dry areas:

  • Abnormally dry (D0) to moderate (D1) drought conditions covered a large part of the western U.S., with pockets of severe (D2) and severe to extreme (D3) drought occurring in some areas, and severe to exceptional (D4) drought lingering in California. —
  • Abnormally dry and drought conditions expanded in the parts of the Plains. —
    • Moderate to severe drought was evident in several pockets, including Texas and Oklahoma in the south and in western South Dakota and adjacent Wyoming and Montana. Decreased rainfall and rain days, and increased evapotranspiration, resulted in drying soils and lowering groundwater levels. According to USDA statistics, 40 percent or more of the topsoil moisture was short or very short in Nebraska (42%), Oklahoma (46%), and Texas (57%); 40 percent or more of the subsoil moisture was short or very short in Texas (48%).
  • Abnormally dry and drought conditions contracted in parts of the Midwest and Northeast and intensified in other parts of the Northeast, where extreme drought developed. —
    • The unusually warmer-than-normal temperatures increased evaporative stress which exacerbated the drought conditions in the Northeast. Soils were dry, vegetation stressed, and groundwater and streamflow levels low. According to USDA statistics, topsoil moisture was short or very short in 40 percent or more of Connecticut (90%), Rhode Island (62%), Massachusetts (46%), and New Hampshire (46%); subsoil moisture was short or very short in 40 percent or more of Massachusetts (86%), Rhode Island (81%), New Hampshire (74%), Connecticut (58%), and Maine (55%); and pasture and rangeland was in poor to very poor condition in 40 percent or more of Maine (82%), Massachusetts (55%), New Hampshire (45%), and Vermont (44%).
  • Drought expanded and intensified in the Southeast to Lower Mississippi Valley, with exceptional drought expanding. —
    • Drought impacts were seen in sparse rain days, low streamflows, increased evapotranspiration, and dry soils, with some areas reporting low groundwater levels. The CMI showed persistent agricultural drought, with areas of stressed vegetation. Water conservation measures were implemented in many communities and several large wildfires had developed from Florida to Kentucky. According to USDA statistics, topsoil moisture was short or very short in 40 percent or more of Mississippi (83%), Georgia (80%), Louisiana (79%), Tennessee (78%), Alabama (76%), Kentucky (61%), and Arkansas (59%); subsoil moisture was short or very short in 40 percent or more of Mississippi (78%), Tennessee (78%), Georgia (75%), Louisiana (74%), Alabama (73%), Arkansas (61%), and Kentucky (58%); and pasture and rangeland was in poor to very poor condition in 40 percent or more of Tennessee (65%), Georgia (63%), and Mississippi (42%).


Hawaii: October 2016 was mostly drier than normal across the Hawaiian Islands. But the last 2, 3, 4, 6, and 7 months were generally wetter than normal. A mixed precipitation anomaly pattern is evident at the longer time scales (last 10, 12, 24, and 36 months). Moderate to severe drought contracted to cover a little under two percent of the state according to the November 1st USDM map.

Alaska climate division precipitation rank map for the current month
Alaska climate division precipitation rank map for the current month.

Alaska: October 2016 was drier than normal across Alaska, giving the state the driest October in the 1925-2016 record, statewide. Based on the climate division maps (last 3, 6, 10, and 12 months), much of the last year has been near to wetter than normal, except in the panhandle. The low elevation station maps show a similar pattern, with the panhandle and southeast drier than normal for the last 2, 3, 4, 6, 7, 10, and 12 months. A wetter-than-normal pattern dominates most areas at the 24- and 36-month time scales. October 2016 temperatures were warmer than normal except in the southeast, as seen on both the divisional and station maps. Warmer-than-normal temperatures dominate at the longer time scales (station maps for the last 2, 3, 10, 12 months) (climate division maps for last 3, 6, 10, 12 months). In fact, the divisional maps show that it was record-warm virtually across the state for the last 10 and 12 months. The combination of unusual warmth and dryness resulted in below-average meltwater content in the mountain snowpack in most areas. About ten percent of the state had abnormal dryness on the November 1st USDM map.

Puerto Rico: Puerto Rico was mostly wetter than normal during October, except for near-normal conditions in the east. But a wetter-than-normal pattern in the west and drier-than-normal pattern in the east is evident at longer time scales (last 2, 3, 6, 10 months). Soils were moist across most of the island. As shown by the November 1st USDM map, abnormal dryness and drought held steady at about 12 percent of Puerto Rico, with moderate drought staying around 5 percent of the island.



CONUS State Precipitation Ranks:

Map showing October 2016 state precipitation ranks Alabama statewide precipitation, October, 1895-2016

October 2016 was drier than normal across much of the CONUS from the Southwest to Southeast, much of the Plains, and parts of the Northeast. The dryness showed up on the statewide level, with 15 states in the CONUS ranking in their driest third of the 1895-2016 record. Six states had the tenth driest, or drier, October, including Alabama (second driest), Louisiana (fifth driest), Texas (sixth driest), Tennessee (seventh driest), Mississippi (eighth driest), and Colorado (tenth driest).

Map showing May-October 2016 state precipitation ranks Alabama statewide precipitation, May-October, 1895-2016

August-October 2016 was drier than normal across much of the Southeast and parts of the West, Plains, and Northeast. The dryness showed up on the statewide level at just a few states, with nine states in the CONUS ranking in their driest third of the 1895-2016 record. Alabama ranked in the top ten driest category with the ninth driest August-October.

A similar pattern of dryness was evident on the May-October map, with 13 states in the CONUS ranking in their driest third of the 1895-2016 record. Three were in the top ten driest category, including Alabama with the fourth driest May-October, Georgia (fifth driest), and Connecticut (seventh driest).

Map showing November-October 2016 state precipitation ranks Connecticut statewide precipitation, November-October, 1895-2016

January-October 2016 also was drier than normal across much of the Southeast and parts of the West, Plains, and Northeast. The dryness showed up on the statewide level with 14 states in these areas ranking in their driest third of the historical record. Connecticut ranked in the top ten driest category with the seventh driest January-October.

For the last 12 months, the pattern was similar except dryness was not as evident in the Southeast. Nine states in the Southwest and Northeast ranked in their driest third of the historical record. Connecticut, again, ranked in the top ten driest category with the sixth driest November-October, rivalling the dryness of the 1960s drought of record. The last five November-October periods have been much drier than average in the state.


Western U.S.


Percent Area of the Western U.S. in Moderate to Extreme Drought, January 1996-present, based on the Palmer Drought Index Percent Area of the Western U.S. in Moderate to Exceptional Drought, January 4, 2000-present, based on the U.S. Drought Monitor

Percent area of the Western U.S. in moderate to extreme drought, January 1900 to present, based on the Palmer Drought Index
Percent area of the Western U.S. in moderate to extreme drought, January 1900 to present, based on the Palmer Drought Index.

As noted earlier, October 2016 was wetter than normal across the Far West, Pacific Northwest, and Northern Rockies, and drier than normal in the Southwest to Central Rockies. October temperatures were near to below normal in the Far West but warmer to much warmer than average the farther south and east one goes. Although this is still early in the snow season, the warm temperatures caused the precipitation to fall more as rain than snow, resulting in a mountain snowpack that was below average in most places, with many locations still snow free.

The above-normal precipitation which fell from Northern California to Montana in October improved drought conditions in these areas, resulting in a decrease in drought area in both the USDM and Palmer analyses. According to the USDM, 25.3 percent of the West was experiencing moderate to exceptional drought at the end of October, about 9.5 percent less than the previous month. The Palmer Drought Index percent area statistic for the West decreased to 24.1 percent.


Northeast U.S.


Northeast region precipitation, January-October, 1895-2016 Percent Area of the Northeast U.S. in Moderate to Exceptional Drought, January 4, 2000-present, based on the U.S. Drought Monitor

As noted above, several states in the Northeast CONUS have had very dry conditions recently. When the Northeast region as a whole is examined, October 2016 ranked as the 35th wettest (88th driest) October in the 1895-2016 record, August-October 2016 ranked 58th wettest (65th driest), May-October ranked 41st driest, January-October ranked 28th driest, and November 2015-October 2016 ranked 34th driest. According to the USDM, 51.2 percent of the Northeast was experiencing moderate to exceptional drought at the end of October, a large increase from the 41.0 percent at the end of the previous month and the largest extent since 2002 in the 17-year USDM record.

Agricultural Belts


Primary Hard Red Winter Wheat Belt precipitation, October, 1895-2016
Primary Hard Red Winter Wheat Belt precipitation, October, 1895-2016.
Primary Hard Red Winter Wheat Belt temperature, October, 1895-2016
Primary Hard Red Winter Wheat Belt temperature, October, 1895-2016.

October serves as the beginning of the growing season for the Primary Hard Red Winter Wheat agricultural belt. October 2016 was generally drier and warmer than normal across the region, ranking as the 16th driest and fourth warmest October, regionwide, in the 1895-2016 record.


NOAA Regional Climate Centers:


A more detailed drought discussion, provided by the NOAA Regional Climate Centers and others, can be found below.


As described by the High Plains Regional Climate Center, the warmth of September continued into October across the High Plains, and dry conditions accompanied the warmth, especially in eastern Colorado and southwestern Kansas where the greatest temperature departures occurred. For instance, Colorado Springs, Colorado and Garden City, Kansas had their 2nd warmest and 3rd warmest Octobers on record respectively, and they both tied for their driest Octobers on record (Colorado Springs period of record 1895-2016, Garden City period of record 1947-2016). These conditions caused soils to dry out quickly and wildfires to spread easily, which prompted the expansion of abnormal dryness and moderate drought to these areas by authors of the USDM. Meanwhile, record precipitation in Montana and above-normal precipitation in northern Wyoming relieved drought conditions and improved streamflows in the Upper Missouri River Basin.

It was quite dry throughout much of the High Plains in October. The driest areas included eastern Wyoming, as well as a swath from eastern Colorado through western Kansas and central Nebraska where precipitation was no more than 25 percent of normal for the month. Although the fall season is generally a drier time of year in the High Plains, the combination of heat and excessive dryness caused some impacts, such as increased wildfire activity and rapidly drying soils. The Junkins Fire near Pueblo, Colorado and the Cottonwood Fire in the Black Hills region of South Dakota were notable for their spatial extents, as thousands of acres were burned. As for soil moisture, both topsoil and subsoil moisture declined considerably during October in Colorado and Kansas. The general pattern of lower streamflows in the Upper Missouri Basin and higher streamflows in the Lower Missouri Basin continued in October. However, streamflows vastly improved in the Upper Basin due to above-normal precipitation. On the contrary, a very warm and dry month caused streamflows to decline across Colorado, especially in the central part of the state. Precipitation was abysmal, as much of the state received 50 percent of normal precipitation, at best.

Areas in drought saw improvement but dryness developed and expanded to new locations throughout the High Plains in October. Overall, the percent area in severe, extreme, or exceptional drought (D2-D4) was reduced by nearly 2 percent, but the area experiencing any level of drought or abnormal dryness (D0-D4) increased from about 29 percent to over 38 percent since late September. A significant reduction in drought occurred in Wyoming this month. Heavy precipitation brought much-needed drought relief, and as a result the percent area in drought (D1-D4) was reduced from over 24 percent to over 9 percent. Areas experiencing severe drought (D2) and extreme drought (D3) in the Black Hills region of South Dakota also received some relief. However, prolonged dryness brought about the development and expansion of abnormal dryness (D0) and moderate drought (D1) across South Dakota, Colorado, and Kansas. Recent dryness prompted the expansion of D1 in southwestern South Dakota, and a new area of D1 was introduced to the northeastern part of the state where agriculture- and wildfire-related impacts were reported. In eastern Colorado, a broad expansion of D0 occurred where several impacts were noted, such as well-above-normal temperatures, blowing dust, dry soils, brown grass, and a delay in the emergence of winter wheat. Similar conditions were reported in western Kansas, so D0 was expanded into the region and a small area of D1 was introduced.

As explained by the Southern Regional Climate Center, October temperatures in the Southern region were consistently above normal as they were in the previous month. Like September, October proved to be a very dry month for the Southern region, with four of six states experiencing a top ten driest October on record (1895-2016). An overwhelming majority of stations in the region received less than a quarter of expected precipitation for the month, with many stations in the southern half of the region reporting less than half an inch (25.4 mm). For the region as a whole, it was the seventh driest October on record (1895-2016).

With consecutive dry and warm months for September and October, drought conditions have changed dramatically in the Southern region. Over the past month, the amount of areal coverage of moderate drought (or worse) has increased from roughly 10 percent to over 42 percent. In addition, the amount of severe drought (or worse) has increased from a little over two percent coverage to over 14 percent coverage. Mississippi is in 100 percent drought coverage, with much of the central portions of the state now showing extreme drought. With the exception of a few counties in the north eastern corner of the state, Tennessee is showing full drought coverage also, with a significant expansion of extreme and exceptional drought in the south eastern counties. Louisiana has shifted from being drought-free to near full coverage of moderate drought, only two and a half months after experiencing a 1000-year flooding event in the southern Parishes in August. Much of Arkansas is also experiencing moderate drought, which as of last month, was also drought-free. Drought conditions are also observed in eastern Texas and eastern Oklahoma, and in the Oklahoma panhandle. Like Tennessee, burn bans are in effect in Mississippi. The ban is issued for all but six counties in the entire state. Over the past two months (September and October), the Mississippi Forestry Commission has responded to over 700 wildfires. It was noted that over 6000 acres (24.28 square km) have already burned. Despite the drought, the Mississippi Crop Progress and Condition Report indicated that as of October 30, 2016, there hasn't been much decline in crop progress relative to the 5-year average. Wheat planting in some parts of the state has been delayed until some measurable rainfall is observed. Farmers are indicating that conditions are extremely dry.

As summarized by the Midwest Regional Climate Center, October precipitation was below normal for the majority of the region and temperatures were well above normal for the second straight month. Although slightly wetter than normal areas touched eight states, areas that were well below normal covered more area than those with above normal rainfall. Kentucky was particularly dry with most of the state receiving less than 50 percent of normal rainfall and some areas in the western part of the state at less than 25 percent of normal.

Drought was completely absent in the Midwest as of the October 4th release of the USDM. The following week moderate drought emerged in southeast Kentucky and spread both to the west and north through the October 25th release when nearly a quarter of Kentucky was in moderate drought. Harvest progress, of corn and soybeans, was running slightly behind the 5-year average as October began. Drier conditions allowed more fieldwork and harvest progress was near the 5-year average by the end of the month. Crop conditions continued to be favorable for much of the region.

As noted by the Southeast Regional Climate Center, temperatures were well above average across much of the Southeast region during October, with numerous extremes observed, and a west-to-east gradient in precipitation totals occurred, ranging from extreme dryness to extreme wetness. The driest locations were found across much of the northern and western portions of the region, including Alabama, the Florida Panhandle, western and central Georgia, western parts of the Carolinas, and southwestern, west-central, and northern Virginia. Monthly precipitation totals ranged between 50 to less than 5 percent of normal in these areas, with no precipitation observed across broad portions of Alabama, Georgia, and the Florida Panhandle. In fact, at least 27 stations did not record any measurable precipitation during the month, including Pensacola, FL, Mobile, AL, and Birmingham, AL. In contrast, the wettest locations were found across a broad portion of the Atlantic coast extending from central Florida to southeastern Virginia. Temperatures were above average and precipitation was above normal across much of Puerto Rico and the U.S. Virgin Islands during the month, with a few drier-than-normal locations in eastern Puerto Rico and St. Croix.

Drought conditions intensified and expanded in coverage across the western half of the Southeast region during October, especially in Alabama and Georgia. The coverage of moderate-to-exceptional (D1-D4) drought in Alabama increased by 50 percent during the month and expanded to encompass the entire state for the first time since March 2011. Extreme-to-exceptional (D3-D4) drought increased by 19 percent in coverage across Georgia and covered approximately one third of the state by the end of the month. In addition, extreme drought expanded into much of Upstate South Carolina and a small portion of western North Carolina. Dryland crops (cotton, peanuts, and soybeans) continued to decline in quality across drought-stricken, interior portions of the region. Pastures and hay fields remained in very poor condition, with many livestock producers having to sell off young cattle due to a shortage of hay. The combination of very low soil moisture and a persistent infestation of fall armyworms delayed the planting of cool season grains in Alabama, Georgia, and South Carolina. The drought contributed to unusually high wildfire activity across Alabama and northwestern Georgia, with nearly 1,200 fires occurring in Alabama during the month.

As explained by the Northeast Regional Climate Center, October was another warmer-than-normal month for the Northeast and the region wrapped up the month with 4.15 inches (105.41 mm) of precipitation, which was 108 percent of normal. The October 6 USDM showed 41 percent of the Northeast was experiencing moderate, severe, or extreme drought, with another 24 percent being abnormally dry. Areas such as central New York, north-central Pennsylvania, and southern coastal Maine received above-normal precipitation, which helped eased drought conditions. However, drought conditions expanded or remained unchanged in eastern Pennsylvania, northern New Jersey, eastern New York, and much of the rest of New England. The USDM released on October 27 indicated 52 percent of the Northeast was in a moderate, severe, or extreme drought, with another 16 percent being abnormally dry. Preliminary USGS data indicated streamflow and groundwater continued to be at record or near record low levels during the month. For instance, the Piscataquis River near Dover-Foxcroft, Maine and the Saco River near Cornish, Maine, both with over 100 years of data, had record low 7-day average streamflow for the October 12-19 period. Shallow, private wells continued to run dry, and water levels in reservoirs continued to decline. An October 21 press release from New Jersey's Department of Environmental Protection indicated water levels for the state's major reservoir systems ranged from less than 45 percent to 74 percent of capacity. Due to low reservoir levels, Connecticut officials declared a rare public water supply emergency for several towns, another city began buying water from the Massachusetts Water Resources Authority, and Dorset, Vermont shut off its water system each night for a week to allow its reservoir to recharge. As of October 27, 166 New Hampshire water systems had water bans and/or restrictions in place. Dwindling water supplies continued to be a challenge for growers. For example, a lack of water caused some cranberry growers in southeastern Massachusetts to delay harvest. Supplemental hay was being used on some western Massachusetts farms due to dried up pastures. Beekeepers in southern Maine reported that honey production was down, with some having no crop at all or possibly not enough for bees to survive the winter. Low yields of corn, soybeans, and hay were reported in parts of New York, with Lewis County farmers harvesting late hay crops to try to make up for the lower yields. Farmers in more drought-stricken counties became eligible for federal aid. In early October, Massachusetts upgraded the Connecticut River Valley to a drought warning and its western region to a drought watch. Northern and central New Jersey were upgraded to a drought watch in early October then a drought warning in late October, while southwestern New Jersey remained in a drought watch. Despite rainfall in late October, which eased extreme drought conditions, the western half of New York remained under a drought warning and the rest of the state under a drought watch due to longer-term precipitation deficits.

As summarized by the Western Regional Climate Center, well above-normal precipitation was observed across a large area of the West this month, extending from central California northeast to eastern Montana. Many October precipitation records were set between northern California and the Canadian border. In contrast, much of the Southwest observed drier-than-normal conditions. October temperatures were generally near to slightly below normal in the coastal states, transitioning to significantly above normal in the Southwest, most notably in the Four Corners states.

Several storm systems impacted the Northwest this month, bringing widespread above normal precipitation to the region. October's abundant precipitation allowed for significant improvement of drought conditions across the Northwest, leaving Washington, western Oregon, far northwestern California, and nearly all of Idaho and Montana free of any drought class designation on the USDM. Precipitation was limited across the Southwest, with most locations receiving less than 75% of their October normal.

Most of Alaska was drier than normal this month, and several locations in southeast Alaska experienced their driest October on record. Juneau observed only 2.59 in (66 mm) precipitation, 30% of normal and the driest October since records began in 1936. Temperatures were above normal in all but the southeastern part of the state, with several locations shattering previous October records. Further south, most of Hawaii observed below normal precipitation, with the exception of some Big Island locations. Honolulu, Oahu, recorded 0.12 in (3 mm) for the month, 6% of normal and the 6th driest October since records began in 1940.

Pacific Islands: The NOAA National Weather Service (NWS) offices, the Pacific ENSO Applications Climate Center (PEAC), and partners provided reports on conditions across the Pacific Islands.

In the U.S. Affiliated Pacific Islands (USAPI) (maps — Federated States of Micronesia, Northern Mariana Islands, Marshall Islands, Republic of Palau, American Samoa, basinwide), October 2016 was wetter than normal at Guam, Koror, Kwajalein, Majuro, Pohnpei, and Yap, and drier than normal at Chuuk, Kapingamarangi, Kosrae, Lukonor, Pago Pago, and Saipan.

Rainfall amounts were below the minimum thresholds (4 or 8 inches) required to meet most monthly water needs at stations in the Federated States of Micronesia (FSM) (Chuuk, Fananu, Kapingamarangi, Nukuoro, and Pingelap) and American Samoa (Pago Pago). October rainfall was above the monthly minimum thresholds at the rest of the regular reporting stations in Micronesia. The monthly precipitation at Pago Pago has been below their 8-inch minimum for the last 5 months, giving June-October a rank of fifth driest out of 51 years, which equates to the 10th percentile. The 4- and 8-inch thresholds are important because, if monthly precipitation falls below the threshold, then water shortages or drought become a concern.

As measured by percent of normal precipitation, Chuuk, Kapingamarangi, Kosrae, and Lukonor have been drier than normal in the short term (October and the last 3 months [August-October 2016]) as well as the long term (year to date [January-October 2016] and last 12 months [November 2015-October 2016]). Guam, Koror, Kwajalein, Majuro, Pohnpei, and Yap were wetter than to near normal in the short term but drier than normal in the long term. Pago Pago was near normal at the 12-month time scale but drier than normal at the other three time scales. Saipan was drier than normal for October but near to wetter than normal for the other three time periods.


X
  • Percent of Normal Precip
  • Precipitation
  • Normals
Pacific Island Percent of 1981-2010 Normal Median Precipitation
Station Name Nov
2015
Dec
2015
Jan
2016
Feb
2016
Mar
2016
Apr
2016
May
2016
Jun
2016
Jul
2016
Aug
2016
Sep
2016
Oct
2016
Nov 2015-
Oct 2016
Chuuk70%82%63%29%85%86%107%91%94%74%86%59%76%
Guam NAS81%74%65%120%79%52%53%125%67%141%124%115%86%
Kapingamarangi89%134%103%65%88%94%34%24%66%91%77%26%64%
Koror69%41%26%30%36%135%115%93%45%61%115%153%71%
Kosrae33%95%60%113%32%23%72%130%88%88%89%90%62%
Kwajalein88%59%64%17%45%21%57%142%101%83%64%168%84%
Lukonor123%56%123%61%51%113%102%73%43%73%120%74%72%
Majuro40%61%14%46%20%22%110%66%90%75%123%120%69%
Pago Pago210%183%34%54%101%329%102%73%81%83%83%55%104%
Pohnpei67%71%102%49%44%60%80%143%79%112%144%120%87%
Saipan64%154%54%105%106%68%87%57%42%186%191%40%104%
Yap37%58%35%34%15%62%113%54%67%88%66%164%70%
Pacific Island Precipitation (Inches)
Station Name Nov
2015
Dec
2015
Jan
2016
Feb
2016
Mar
2016
Apr
2016
May
2016
Jun
2016
Jul
2016
Aug
2016
Sep
2016
Oct
2016
Nov 2015-
Oct 2016
Chuuk7.469.256.402.097.0810.7312.1110.6111.279.5010.046.74103.28
Guam NAS5.963.772.623.631.631.311.807.736.7720.8515.6513.1484.86
Kapingamarangi8.2813.209.406.0410.0212.784.073.309.337.387.612.1493.55
Koror7.864.592.642.532.689.9013.5516.258.288.2013.5118.06108.05
Kosrae4.5515.379.9514.565.153.9912.7018.9913.0712.4812.719.87133.39
Kwajalein9.983.902.020.461.051.133.809.819.968.126.9018.7375.86
Lukonor11.186.3510.375.444.7512.8311.928.496.8410.3112.238.41109.12
Majuro5.336.931.113.171.332.0511.127.2710.098.7813.7315.2886.19
Pago Pago21.3323.534.496.4910.7630.879.893.884.484.495.455.12130.78
Pohnpei9.9511.4113.494.645.7611.0116.0621.1812.1215.9118.1318.39158.05
Saipan3.615.941.362.722.001.782.072.053.7624.4019.314.2673.26
Yap3.314.932.231.770.703.478.906.4610.0313.108.8920.0083.79
Pacific Island 1981-2010 Normal Median Precipitation (Inches)
Station Name Nov
2015
Dec
2015
Jan
2016
Feb
2016
Mar
2016
Apr
2016
May
2016
Jun
2016
Jul
2016
Aug
2016
Sep
2016
Oct
2016
Nov 2015-
Oct 2016
Chuuk10.6111.2510.107.258.3212.4711.3011.6611.9812.8611.7111.51136.77
Guam NAS7.385.114.013.032.072.533.406.1810.1414.7412.6611.4499.09
Kapingamarangi9.279.849.159.2711.4313.6412.0813.7814.158.139.938.19145.85
Koror11.3911.1610.188.567.447.3211.8317.4818.5313.5011.7711.84152.90
Kosrae13.8316.1116.6712.9316.0617.5117.7514.6414.9114.2214.2210.94213.87
Kwajalein11.286.663.162.642.355.266.726.939.879.7410.7411.1890.41
Lukonor9.0811.278.418.939.2611.3111.6911.6515.9314.0410.1511.32151.36
Majuro13.4411.397.746.886.589.4210.1111.0111.1711.6911.1712.73125.25
Pago Pago10.1412.8413.3412.0010.689.399.665.335.555.386.539.26125.57
Pohnpei14.8316.0813.189.5513.1718.4119.9614.8115.4314.2612.5515.27182.36
Saipan5.613.852.532.591.892.632.383.628.9113.1310.0910.6270.25
Yap8.838.516.395.194.565.637.8512.0415.0814.8213.5012.18120.31

The end of the El Niño several months ago and development of ENSO-neutral conditions in the tropical Pacific has resulted in the return of much-needed rainfall to most of the USAPI region. The rains ended the drought, but long-term precipitation deficits continued for some stations, as seen in the table below.

An analysis of historical data for the USAPI stations in the Global Historical Climatology Network-Daily (GHCN-D) dataset, augmented with fill-in data from the 1981-2010 Normals, indicated that, even though rains have returned during the last one to five months, several stations still had near-record dryness during November 2015-October 2016. The following table lists the precipitation ranks for October 2016, June-October 2016 (last 5 months), and November 2015-October 2016 (the last 12 months). Some stations have a long period of record and their dataset is fairly complete, while other stations have a shorter period of record and the dataset has some missing data. October 2016 was the driest October for Saipan (based on a record from 1981-2016). June-October 2016 was the second driest such 5-month period on record for Chuuk (1951-2016), Jaluit (1981-2016), Lukonor (1981-2016), and Nukuoro (1981-2016), and third driest for Kapingamarangi (1962-2016). The last twelve months (November 2015-October 2016) was the driest such November-October period on record at Jaluit and second driest at Kapingamarangi, Majuro (1954-2016), and Yap (1951-2016).

Rank, Number of Years with data, and Period of Record for USAPI stations for October 2016, June-October 2016, and November 2015-October 2016.
Rank of 1 = driest.
Station Oct 2016
Rank
Oct
No. of Years
Jun- Oct 2016
Rank
Jun- Oct
No. of Years
Nov 2015- Oct 2016
Rank
Nov- Oct
No. of Years
Period of Record
Jaluit 25 33 2 33 1 31 1981-2016
Koror 57 66 17 65 4 65 1951-2016
Woleai 32 32 13 25 3 22 1968-2016
Yap 63 66 12 65 2 65 1951-2016
Majuro 42 63 21 63 2 62 1954-2016
Ulithi 35 35 14 34 3 32 1981-2016
Ailinglapalap 29 33 13 32 3 30 1981-2016
Kosrae 13 48 11 38 3 30 1954-2016
Lukonor 7 32 2 20 4 20 1981-2016
Saipan 1 36 31 36 17 27 1981-2016
Pohnpei 50 66 47 65 6 65 1951-2016
Kwajalein 61 65 41 65 8 64 1952-2016
Kapingamarangi 5 27 3 17 2 15 1962-2016
Chuuk 7 66 2 65 3 65 1951-2016
Guam 36 60 35 60 15 59 1957-2016
Nukuoro 8 34 2 32 8 31 1981-2016
Pago Pago 8 51 5 51 33 50 1966-2016
Utirik 15 15 5 5 N/A 0 1985-2016

Precipitation amount for current month for U.S. Affiliated Pacific Island stations

Percent of normal precipitation for current month for U.S. Affiliated Pacific Island stations

Percent of normal precipitation for last 3 months for U.S. Affiliated Pacific Island stations

Percent of normal precipitation for the year to date for U.S. Affiliated Pacific Island stations

Percent of normal precipitation for last 12 months for U.S. Affiliated Pacific Island stations

SPI values for seven time periods for Pacific Islands, computed by the Honolulu NWS office.
SPI values for seven time periods for Pacific Islands

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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.):

States
alabama arizona arkansas california colorado connecticut
delaware florida georgia idaho illinois indiana
iowa kansas kentucky louisiana maine maryland
massachusetts michigan minnesota mississippi missouri montana
nebraska nevada new hampshire new jersey new mexico new york
north carolina north dakota ohio oklahoma oregon pennsylvania
rhode island south carolina south dakota tennessee texas utah
vermont virginia washington west virginia wisconsin wyoming

Regional
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.

National
Contiguous United States

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Contacts & Questions
For additional, or more localized, drought information, please visit:

Citing This Report

NOAA National Centers for Environmental Information, State of the Climate: Drought for October 2016, published online November 2016, retrieved on December 3, 2016 from http://www.ncdc.noaa.gov/sotc/drought/201610.