Drought - October 2017


Issued 14 November 2017
Contents Of This Report:
Map showing Palmer Z Index
Percent Area of U.S. in Moderate to Extreme Drought, Jan 1996 to present
Northeast Montana (climate division 6) precipitation, November-October, 1895-2017

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 October 31, 2017
The U.S. Drought Monitor drought map valid October 31, 2017.

During October 2017, the upper-level circulation pattern underwent a couple significant shifts over the contiguous United States (CONUS) at mid-month and a little later in the month, changing from a predominantly trough-West/ridge-East pattern during the first half of the month to a predominantly zonal flow for the middle third of the month, ending with mostly a ridge-West/trough-East pattern for the last third of the month. Fronts and low pressure systems brought precipitation to various parts of the CONUS at different parts of the month, with moisture from the remnants of Hurricane Nate and Tropical Storm Philippe helping in the East. The resulting monthly precipitation anomaly pattern consisted of above-normal precipitation in the Pacific Northwest, from the central Plains to Great Lakes, from the central Gulf of Mexico coast to the Northeast, and across most of Alaska and Hawaii. Much of the Southwest, southern and northern Plains, Lower Mississippi Valley, and parts of the coastal Southeast were drier than normal. The rain in the Northwest helped extinguish a number of wildfires which had been burning in the West (wildfire maps for October 1, 11, 18, 23, 31). Drought and abnormal dryness contracted in the wet areas from the Pacific Northwest to northern Plains, from the central Plains to Great Lakes, across the Northeast, and in Hawaii. But drought and abnormal dryness expanded in parts of the Southwest, Texas, Lower Mississippi Valley, and Southeast where October was dry and the last two, three, and even six months have been drier than normal. Contraction outweighed expansion, so the USDM-based national moderate-to-exceptional drought footprint across the CONUS contracted from 14.4 percent of the CONUS at the end of September to 12.0 percent of the CONUS at the end of October (from 12.1 percent to 10.1 percent for all of the U.S.). According to the Palmer Drought Index, which goes back to the beginning of the 20th century, about 11.6 percent of the CONUS was in moderate to extreme drought at the end of October, an increase from last month's 8.9 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.






Drought conditions at the end of the month, as depicted on the October 31st, 2017 USDM map, included the following core drought and abnormally dry areas:

Moderate drought was eliminated, with only a few areas of abnormal dryness remaining, in the Northeast. There was no drought or abnormal dryness in Puerto Rico and Alaska.



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 country 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 parts of the southern Plains to Lower Mississippi Valley, decreasing previous long-term wetness and over North Dakota, adding to long-term drought conditions. Short-term dry conditions occurred across much of the Southwest, expanding long-term drought conditions. Short-term wet conditions occurred in the Midwest, Great Lakes, and Northeast, contracting or eliminating long-term drought conditions.



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 in parts of southern Arizona is evident at all time scales. Parts of the Southwest are dry at the 1- to 9-month time scales, with most of the Southwest dry for the last month. Parts of the Pacific Northwest are dry at the 6-month time scale, but wet at the other time scales. The northern Plains are dry at the 1-month and 6- to 12-month time scales, but near normal to wet at the 2- to 3-month time scales, with parts (the western Dakotas) dry at the 24-month time scale. The southern Plains to Lower Mississippi Valley are dry for the last 2 months, but wet at longer time scales. Parts of southern New England are dry at the 24-month time scale, but near to wetter than normal at the other time scales. Some dryness is evident in the Ohio Valley, Mid-Atlantic region, and Carolinas at the 2- or 3-month time scales.


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



Regional Discussion




Map of percent of normal precipitation for Hawaii, January-October 2017
Map of percent of normal precipitation for Hawaii, January-October 2017.

Hawaii: October 2017 was wetter than normal across most of the Hawaiian Islands. This resulted in a mixed precipitation anomaly pattern for the last 2 to 3 months, with dry conditions dominating on the Big Island and Oahu at longer time scales (last 4, 7, 10, and 12 months). Dry conditions were more widespread at the 24- and 36-month time scales. Streamflow had mostly recovered to near normal. While abnormal dryness and drought contracted, moderate to extreme drought still covered almost half of the state on the October 31st, 2017 USDM map.



Alaska divisional precipitation rank map, November 2016-October 2017
Alaska divisional precipitation rank map, November 2016-October 2017.

Alaska: October 2017 was drier than normal across the panhandle and interior southeast of Alaska but wetter than normal across the rest of the state (climate division, gridded, and low elevation station maps) except at some interior high elevation (SNOTEL) stations. The precipitation anomaly pattern was similar (at the low elevation analyses) for the last 2, 3 (climate division, gridded, and low elevation station maps), and 4 months, with wet conditions dominating at the 6- (climate division, low elevation station maps) to 7-month time scales. There were some drier-than-normal areas in the south (climate division, low elevation station maps) and northwest for the year-to-date, and mostly south at the 12- (climate division, SNOTEL, and low elevation station maps) month time scales. There were a few areas of below-normal precipitation at southern stations at the 24- and 36-month time scales. Temperatures were predominantly warmer than normal for the last 1 (low elevation station, gridded, divisional maps), 2, 3 (low elevation station, gridded, divisional maps), and 6 months, with some near to cooler-than-normal temperatures in the south at the 10- (low elevation station, gridded, divisional maps) and 12- (low elevation station, divisional) month time scales. Mountain snow water content was mostly below normal, but this is early in the snow season. Streamflow was above normal. Alaska remained free of drought and abnormal dryness on the October 31st USDM map.



Puerto Rico:

Precipitation anomaly maps were not available for Puerto Rico this month. Streamflow was mostly above normal across the island. As seen on the October 31st, 2017 USDM map, Puerto Rico was free of drought and abnormal dryness. Puerto Rico USDM map, October 31, 2017



CONUS State Precipitation Ranks:

Map showing October 2017 state precipitation ranks Utah statewide precipitation, October, 1895-2017

October 2017 was drier than normal across much of the Southwest, southern Plains, and Lower Mississippi Valley, and parts of the northern Plains. On a statewide basis, nine states ranked in the driest third of the 123-year historical record with two states in the top ten driest category. Both Arizona and Utah had the fifth driest October in the 1895-2017 record. North Dakota ranked eleventh driest.

Map showing August-October 2017 state precipitation ranks Arizona statewide precipitation, August-October, 1895-2017

August-October 2017 was drier than normal across much of the Southwest, the Mid-Mississippi Valley to parts of the Ohio Valley, and parts of the northern High Plains and Southeast. On a statewide basis, six states ranked in the driest third of the historical record with Arizona having the sixth driest August-October on record.

Map showing May-October 2017 state precipitation ranks Montana statewide precipitation, May-October, 1895-2017

The last six months were drier than normal across much of the West to northern Plains and parts of the Mid-Mississippi Valley. On a statewide basis, five states ranked in the driest third of the historical record with Montana having the seventh driest May-October on record and California the ninth driest.

Map showing January-October 2017 state precipitation ranks Arizona statewide precipitation, August-October, 1895-2017

Northeast Montana (climate division 6) precipitation, November-October, 1895-2017

The year to date was mostly near to wetter than normal across the CONUS, with notable drier-than-normal conditions evident in only the northern Plains and parts of the Southwest. On a statewide basis, only three states (in these regions) ranked in the driest third of the historical record with North Dakota having the tenth driest January-October on record.

The last twelve months had a similar precipitation anomaly pattern. The northern Plains were drier than normal, with northeast Montana (climate division 6) having the driest November-October on record. On a statewide basis, none of the contiguous states ranked in the top ten driest category and only two were in the driest third of the historical record.


Agricultural Belts


Primary Hard Red Winter Wheat Belt precipitation, October, 1895-2017
Primary Hard Red Winter Wheat Belt precipitation, October, 1895-2017.
Primary Hard Red Winter Wheat Belt temperature, October, 1895-2017
Primary Hard Red Winter Wheat Belt temperature, October, 1895-2017.

October 2017 was wetter than normal across most of the Primary Hard Red Winter Wheat agricultural belt, with near-normal temperatures. The month ranked as the 41st wettest and 52nd warmest October, regionwide, in the 1895-2017 record.

On a national scale, as of October 24th, 2017, only 4 percent of corn production, 5 percent of soybean production, 14 percent of hay acreage, 10 percent of cattle inventory, and 10 percent of winter wheat production were within an area experiencing drought, but 37 percent of spring wheat production was. All of these values are less than they were a month ago. According to October 30th reports by the U.S. Department of Agriculture (USDA), only 11 percent of the nation's corn crop was in poor to very poor condition (but most of the crop has already been harvested), 12 percent of winter wheat was in poor to very poor condition, and 25 percent of the nation's pasture and rangeland was in poor to very poor condition, mostly in the northern Plains. Twenty-six percent of the nation's topsoil moisture and 32 percent of subsoil moisture were short to very short of moisture. These soil moisture conditions were mostly in the northern Plains, West, Lower to Mid-Mississippi Valley (Arkansas), and northern New England (Maine).


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, a stark contrast in precipitation patterns existed across the High Plains during October, with wet conditions occurring early in the month in the southern and eastern parts of the region and mostly dry conditions elsewhere. Precipitation records were set on both sides of the spectrum, as there were locations that ranked among the top 10 wettest and top 10 driest Octobers on record. The wetness presented problems for producers harvesting their crops, as well as those planting winter wheat. Temperatures were largely near normal, and most of the region experienced a hard freeze in October, which ended the growing season. Drought conditions remained but continued to improve in some parts of the Northern Plains, particularly in areas of Montana that received heavy precipitation early in the month.

With several locations ranking among the top 10 wettest or driest Octobers, the High Plains region experienced both ends of the precipitation spectrum this month. Much of the High Plains were dry, with North Dakota experiencing the most extreme dryness where precipitation was less than 10 percent of normal in some areas. This resulted in Grand Forks and Dickinson having their 3rd driest and 6th driest Octobers on record, respectively. The wettest areas included extreme southeastern South Dakota, eastern Nebraska, and eastern Kansas where October precipitation ranged from 130-300 percent of normal. While the dryness that occurred throughout much of the region caused few issues for agriculture, the wetness was quite problematic.

Drought conditions continued to improve on the whole across the High Plains during October, aided by heavy rains in late September and reduced evaporative demand as the growing season wound down. According to the USDM, the area in drought (D1-D4) across the 6-state region declined from approximately 21 percent to 14 percent. The majority of the improvement occurred across the western Dakotas, particularly in North Dakota where extreme drought (D3) and exceptional drought (D4) conditions were removed. While drought continued to improve in parts of South Dakota, an area of D3 conditions in the west-central portion of the state persisted. In fact, drought conditions deteriorated slightly in the latter part of October across this area due to below-normal precipitation. Drought conditions vastly improved throughout Montana in October, with the large area of D4 in the north-central part of the state being removed and conditions improving elsewhere. Also, improvements in moderate drought (D1) were noted in Kansas where October rainfall was plentiful. While dryness in the fall is not of tremendous concern (and, it is even welcomed by producers harvesting their crops), it is still important to have ample soil moisture going into winter to ensure it is adequate for spring planting. This is even more critical for areas that have recently experienced drought, such as the Dakotas. Much of this region was dry in October, so precipitation is needed in this region to replenish soil moisture before the ground freezes.

As explained by the Southern Regional Climate Center, October temperatures were warmer than normal for most of the region and precipitation varied spatially throughout the region. Parts of western Tennessee, northern and central Mississippi, northeastern, central and southern Arkansas, northern, central, and southwestern Louisiana, south central Oklahoma, and central, southern, and western Texas received 50 percent or less of normal precipitation. There were a few areas of 5 percent or below normal precipitation in central and western Texas and the panhandle of Oklahoma. In contrast, central and eastern Tennessee, southeastern Mississippi, southeastern Louisiana, northern and central Oklahoma, and northern and extreme southern Texas received 150 percent or more of normal precipitation. There were areas of 300 percent or more of normal precipitation in the panhandle of Texas, southeastern Mississippi, and eastern Tennessee.

During October 2017, drought conditions worsened to moderate in east central Mississippi, parts of northern Louisiana, northeastern Texas, southwestern Oklahoma, and western, central, northern, and southern Arkansas. Moderate drought conditions persisted in southern Texas and a small area of north central Oklahoma. A small area of severe drought developed in southern Texas. Abnormally dry conditions expanded throughout parts of the SRCC region and now include: northern and central Mississippi, southeastern Arkansas, northern and central Louisiana, and parts of western Texas. Parts of northeastern Oklahoma and central Texas improved from abnormally dry to normal.

As summarized by the Midwest Regional Climate Center, October precipitation was above normal for most of the Midwest, and temperatures were above normal for the first three weeks of October before dropping to below normal in the final week. Precipitation totals were 150 percent of normal in parts of all nine Midwest states with large parts of Iowa, Michigan, southern Minnesota, and northern Illinois receiving more than 200 percent of normal precipitation. Drier than normal areas with less than 75 percent of normal were in northwestern Minnesota and southeastern Missouri. Drought eased in the Midwest overall but Missouri trended the other way. For the region as a whole, drought areas dropped from 12 percent to 7 percent while the area noted as abnormally dry or in drought dropped from about half the region to about a quarter of the region. Drought expanded in southeastern Missouri during October.

As noted by the Southeast Regional Climate Center, temperatures were above average across the Southeast region during October and precipitation was highly variable with several wet extremes recorded. Unusual dryness was found in portions of north-central Florida, east-central and southeastern Georgia, central and southern South Carolina, and central North Carolina, where monthly precipitation totals were 50 to less than 25 percent of normal.

While over 97 percent of the Southeast region was drought-free at the end of October, abnormally dry (D0) conditions were observed in portions of every state except Florida. Indeed, the coverage of abnormally dry conditions across the region increased from 13 percent on October 3rd to 23 percent on October 31st. Above-average temperatures and a persistent lack of rainfall led to the development of moderate (D1) drought in portions of central North Carolina and south-central Virginia, as well as localized areas of north-central South Carolina and west-central Alabama. Predominately warm, dry weather across the Southeast was beneficial for crop harvesting and hay cutting during the month, but some pastures and crop fields were stressed by below-normal precipitation. Good yields of cotton, soybeans, and peanuts were reported across much of the region north of Florida. However, insufficient soil moisture delayed the planting of winter grains in drier areas, while livestock producers in parts of North Carolina and Virginia began feeding hay to their cattle due to poor pasture conditions.

As explained by the Northeast Regional Climate Center, the Northeast had its second warmest October since recordkeeping began. The first three weeks of October were drier than normal for a large portion of the region, but back-to-back storms late in the month caused the Northeast to wrap up October on the wet side of normal. The USDM released on October 5 showed 4 percent of the Northeast was in a moderate drought and 41 percent of the region was abnormally dry. Maine was the only state experiencing moderate drought at the start of the month, but drought expanded into the rest of New England over the next three weeks. In addition, abnormal dryness expanded across the Northeast. The USDM released on October 26 showed 12 percent of the Northeast was in a moderate drought and 51 percent of the region was abnormally dry. The dry conditions contributed to below-normal streamflow and groundwater levels in parts of the region. There were a few reports of shallow wells going dry in Maine, and two water companies, one in Connecticut and one in Pennsylvania, asked customers to reduce water use. The dry conditions also contributed to elevated fire danger in New England, with several wildfires in Maine in October. However, two storms brought heavy precipitation to the Northeast late in the month, which erased moderate drought and eased much of the abnormally dry conditions in the region. The USDM released on November 2 showed 10 percent of the region was abnormally dry.

As summarized by the Western Regional Climate Center, temperatures were cooler than normal along the northern tier of the West and warmer than normal over the Southwest. A series of storms mid-month brought above normal precipitation to the Pacific Northwest, while much of the Southwest, with the exception of parts of New Mexico, remained drier than normal. At month's end, snowpack was 150-300% of normal across the northern tier of the West. This month's precipitation supported improvement of drought conditions in the USDM across a large portion of the Northwest. Eastern New Mexico also observed above normal precipitation, resulting mostly from a storm during the first week of the month. Much of the Southwest observed very little precipitation, not uncommon for October. Tucson, Arizona, observed no measurable precipitation, tied with 10 other years in its 72-year record. Expansion of moderate drought conditions was observed in southwestern and eastern Arizona this month in response to lackluster rains during the North American Monsoon season, which ended September 30. San Diego, California, also reported no measurable precipitation, same as 16 other years in its 79-year record. Salt Lake City, Utah, recorded 0.18 in (5 mm), 12% of normal and the 9th driest year since records began in 1928.

Conditions were warmer and wetter than normal across Alaska, with the exception of the Southeast, where temperatures were near normal and precipitation was generally below normal. Further south, precipitation was variable across Hawaii, though many stations reported above normal precipitation. Much of this precipitation occurred due to thunderstorms associated with a slow moving cold front October 23-24.

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 [FSM], Northern Mariana Islands, Marshall Islands [RMI], Republic of Palau, American Samoa, basinwide), October 2017 was drier than normal at Saipan, Kapingamarangi, Pohnpei, and Kwajalein and wetter than normal at Koror, Yap, Guam, Chuuk, Lukonor, Kosrae, Majuro, and Pago Pago.

Rainfall amounts were below the minimum thresholds (4 or 8 inches) required to meet most monthly water needs at Fananu and Kapingamarangi (in the FSM); and Ailinglapalap, Jaluit, Utirik, and Wotje (in the RMI). October rainfall was above the monthly minimum thresholds at the rest of the regular reporting stations in Micronesia. The 4- and 8-inch thresholds are important because, if monthly precipitation falls below the threshold, then water shortages or drought become a concern.

Significant dryness developed in the northern Marshall Islands in December 2016, with six of the last eleven months having less than 2 inches each at Utirik (nine had less than 8 inches), and five of the last eleven months having less than 2 inches each at Wotje (nine had less than 8 inches). Eight inches is the monthly minimum in the RMI. October 2017 was the wettest month since November 2016 at Utirik with 6.22 inches of rain and ranked in the middle of the historical distribution (ninth driest out of 16 years of data). But July-October through April-October were still the driest such seasons on record (even though the record is short for these seasons). October 2017 was the fifth driest October in 34 years of record for Jaluit and fourth driest in 34 years of record for Ailinglapalap. June-October through April-October were the driest such seasons in the 34-year record for Jaluit, and May-October ranked third driest out of 33 years for Ailinglapalap. The September 28 th Drought Information Statement issued by the National Weather Service office on Guam noted that drought continues to be a serious concern for the northern Marshall Islands, especially Utirik and likely Enewetak, Ailuk, and other islands north of 10 degrees North latitude, following an April 24th declaration of a state of emergency by the President of the RMI for the northern atolls and islands affected by the dry conditions.

As measured by percent of normal precipitation, Saipan has been drier than normal in the short term (October and the last 3 months [August-October]) as well as the long term (year to date [January-October] and last 12 months [November 2016-October 2017]). Lukonor was wetter than normal for October but drier than normal for the other three time periods. Kapingamarangi and Pohnpei were drier than normal in the short term but near to wetter than normal in the long term. Kwajalein was drier than normal for October, Yap drier than normal for August-October, and Chuuk drier than normal for the year to date, but all three stations were wetter than normal for the other three time periods. Guam, Koror, Kosrae, Majuro, and Pago Pago were near to wetter than normal at all four time periods.


X
  • Percent of Normal Precip
  • Precipitation
  • Normals
Pacific Island Percent of 1981-2010 Normal Median Precipitation
Station Name Nov
2016
Dec
2016
Jan
2017
Feb
2017
Mar
2017
Apr
2017
May
2017
Jun
2017
Jul
2017
Aug
2017
Sep
2017
Oct
2017
Nov 2016-
Oct 2017
Chuuk98%176%113%114%189%60%83%73%99%91%110%127%104%
Guam NAS137%170%155%167%256%340%56%136%97%66%118%161%108%
Kapingamarangi71%114%159%207%126%159%114%81%102%41%92%72%100%
Koror144%64%131%175%245%76%107%89%130%104%161%118%114%
Kosrae56%168%103%213%150%112%115%80%104%93%155%143%104%
Kwajalein126%156%285%212%46%65%77%156%70%64%205%88%116%
Lukonor198%128%138%66%160%85%80%60%103%63%84%116%91%
Majuro129%103%228%138%199%110%49%118%112%111%187%143%130%
Pago Pago127%111%72%153%52%87%240%93%84%145%96%217%108%
Pohnpei115%142%182%71%115%96%92%141%113%55%122%81%107%
Saipan79%95%182%199%108%115%66%128%72%65%84%66%85%
Yap156%101%198%370%205%110%69%68%121%55%93%156%118%
Pacific Island Precipitation (Inches)
Station Name Nov
2016
Dec
2016
Jan
2017
Feb
2017
Mar
2017
Apr
2017
May
2017
Jun
2017
Jul
2017
Aug
2017
Sep
2017
Oct
2017
Nov 2016-
Oct 2017
Chuuk10.3919.8311.378.2715.747.519.408.5011.8611.6512.9214.64142.08
Guam NAS10.138.686.225.065.308.601.898.409.869.7314.9218.47107.26
Kapingamarangi6.5811.2214.5419.1814.4421.7013.7511.1514.473.359.135.93145.44
Koror16.387.1313.3014.9918.265.5412.6115.5324.1413.9818.9014.03174.79
Kosrae7.7626.9917.2127.5124.1619.6220.3411.7315.5713.2322.0215.65221.79
Kwajalein14.1610.369.005.601.073.445.2010.806.916.2822.069.83104.71
Lukonor18.0214.4211.585.9014.839.619.416.9716.478.888.5113.10137.7
Majuro17.3611.7717.659.5013.0710.364.9313.0312.5213.0020.9318.21162.33
Pago Pago12.8614.249.5718.325.608.1423.234.944.667.786.2620.11135.71
Pohnpei17.0022.8324.006.7615.1617.6818.4520.8517.457.8215.2712.31195.58
Saipan4.423.674.615.152.043.021.584.636.458.598.477.0159.64
Yap13.788.5912.6719.199.356.195.408.1618.278.2012.5918.99141.38
Pacific Island 1981-2010 Normal Median Precipitation (Inches)
Station Name Nov
2016
Dec
2016
Jan
2017
Feb
2017
Mar
2017
Apr
2017
May
2017
Jun
2017
Jul
2017
Aug
2017
Sep
2017
Oct
2017
Nov 2016-
Oct 2017
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 following 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, helps put the current data into historical perspective by computing ranks based on the period of record. The table below lists the precipitation ranks for October 2017, May-October 2017 (last 6 months), and November 2016-October 2017 (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.

Rank, Number of Years with data, and Period of Record for USAPI stations for October 2017, May-October 2017, and November 2016-October 2017.
Rank of 1 = driest.
Station Oct 2017
Rank
Oct
No. of Years
May- Oct 2017
Rank
May- Oct
No. of Years
Nov 2016- Oct 2017
Rank
Nov- Oct
No. of Years
Period of Record
Jaluit 5 34 1 34 8 32 1981-2017
Koror 42 67 47 66 61 66 1951-2017
Woleai 22 33 7 24 8 23 1968-2017
Yap 62 67 23 66 53 66 1951-2017
Majuro 52 64 48 63 59 63 1954-2017
Mili 27 34 MSG 33 MSG 31 1981-2017
Ulithi 36 36 13 35 MSG 32 1981-2017
Ailinglapalap 4 34 4 33 21 31 1981-2017
Kosrae 39 49 22 37 21 31 1954-2017
Lukonor 22 33 4 21 10 21 1981-2017
Saipan 6 37 4 37 3 28 1981-2017
Pohnpei 15 67 21 66 45 66 1951-2017
Kwajalein 22 66 28 65 42 65 1952-2017
Kapingamarangi 15 28 9 17 10 16 1962-2017
Chuuk 42 67 9 66 34 66 1951-2017
Guam 54 61 31 61 39 60 1957-2017
Nukuoro 35 35 32 33 30 32 1981-2017
Pago Pago 50 52 45 52 37 51 1966-2017
Wotje 13 34 22 34 17 31 1981-2017
Utirik 9 16 1 4 MSG 0 1985-2017

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 2017, published online November 2017, retrieved on November 18, 2017 from https://www.ncdc.noaa.gov/sotc/drought/201710.

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