Contents Of This Report: |
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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
A high pressure ridge dominated the upper-level circulation over the western CONUS during the first half of November, deflecting Pacific fronts and low pressure systems into Canada and leaving much of the West dry. The ridge also contributed to warmer-than-normal temperatures in the West during the first half of the month, which enhanced evapotranspiration. The ridge forced a trough to develop downstream over eastern North America. This pattern created a northwesterly flow over the central portions of North America which funneled cold Canadian air masses into the CONUS east of the Rockies, resulting in colder-than-normal temperatures. Some Gulf of Mexico moisture was drawn northward in the surface flow behind some of the air masses, resulting in precipitation along subsequent fronts, but the Canadian air masses were mostly dry so much of the country east of the Rockies was drier than normal during this period. The upper-level circulation moderated during the second half of the month, with Pacific weather systems transiting across the West and into the Plains, bringing cooler-than-normal temperatures and above-normal precipitation. Cutoff lows and East Pacific moisture from the remnants of Tropical Storm Raymond increased the precipitation, especially across the Southwest. With this more westerly flow, the Pacific systems drew in Gulf of Mexico and Atlantic moisture, leaving behind above-normal precipitation in some areas as they tracked from the Plains to Northeast. For the month as a whole, the temperature pattern from the first half dominated, leaving the CONUS east of the Rockies colder than normal and much of the West near to warmer than normal. Areas that received significant precipitation at some time during the month were wetter than normal. These monthly wet areas include the Southwest, parts of the central to northern Rockies and Plains, western Texas to the Ohio Valley, parts of the coastal Southeast, and parts of the Great Lakes and northern New England. The areas missed by the precipitation were drier than normal for the month and included the Pacific Northwest, the northern half of California to parts of the northern Rockies, the central Plains to southern Great Lakes, much of Texas and the Gulf Coast states, and much of the Mid-Atlantic to southern New England. Much of Hawaii, the eastern half of Puerto Rico, and the U.S. Virgin Islands were also drier than normal for November, while most of Alaska was wetter than normal. Most of the U.S.-Affiliated Pacific Island (USAPI) stations received enough rainfall to exceed the monthly minimum needed to meet most water needs, so drought was not an issue. As a result of these conditions, drought and abnormal dryness expanded or intensified in the Far West, central Plains, northeast Texas, southern Florida, and parts of Hawaii and Puerto Rico. Drought and abnormal dryness contracted or became less intense in parts of the Southwest and Texas, and much of the Southeast. Drought contraction was more than expansion this month, with the USDM-based national moderate-to-exceptional drought footprint across the CONUS falling from 17.9 percent of the CONUS at the end of October to 11.7 percent of the CONUS at the end of November (from 15.6 percent to 9.9 percent for the 50 States and Puerto Rico). According to the Palmer Drought Index, which goes back to the beginning of the 20th century, about 5.7 percent of the CONUS was in moderate to extreme drought at the end of November, decreasing about 2.3 percent from the 8.0 percent at the end of October.
Drought conditions at the end of November, as depicted on the December 3rd, 2019 USDM map, included the following core drought and abnormally dry areas:
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Moderate (D1) to severe (D2) drought covered a large part of the Southwest, with abnormal dryness (D0) spreading to California and northward into the Pacific Northwest. The November precipitation was heavier in the southern portions of the Southwest than the northern portions. The November precipitation was not enough to make up the deficits in the Four Corners area even for this water year to date (last 2 months), and the deficits in the D1-D2 area extend out to the last 9 months and beyond. The long-term deficits have lowered groundwater levels and (in New Mexico) reduced reservoir storage, with some areas still experiencing soil moisture shortages (NLDAS top soil and total soil moisture model, CPC soil moisture model, VIC soil moisture model). Dryness in the Pacific Northwest and California is evident in groundwater estimations, streamflow observations, snow cover (satellite observations and SNOTEL stations), vegetation-based indicators (QuickDRI), soil moisture indicators (NLDAS top soil and total soil moisture model, CPC soil moisture model, VIC soil moisture model, GRACE satellite-based estimations of surface soil moisture and root zone soil moisture, SMOS satellite observations), and (in Washington) reduced reservoir storage. In New Mexico, according to U.S. Department of Agriculture (USDA) reports, 44 percent of the pasture and rangeland was in poor to very poor condition, and 57 percent of topsoil moisture and 68 percent of subsoil moisture were rated short or very short (dry or very dry). In Colorado, ten percent of the pasture and rangeland was in poor to very poor condition, and 42 percent of topsoil moisture and 37 percent of subsoil moisture were rated short or very short. In Utah, 14 percent of the pasture and rangeland was in poor to very poor condition, and 25 percent of topsoil moisture and 30 percent of subsoil moisture were rated short or very short. In Oregon, 47 percent of the pasture and rangeland was in poor to very poor condition, and 44 percent of topsoil moisture and 54 percent of subsoil moisture were rated short or very short. In Washington, 32 percent of the pasture and rangeland was in poor to very poor condition, and 16 percent of topsoil moisture and 20 percent of subsoil moisture were rated short or very short. In Idaho, 27 percent of the pasture and rangeland was in poor to very poor condition, and 33 percent of topsoil moisture and 45 percent of subsoil moisture were rated short or very short.
- The percent area of the West (from the Rockies to the West Coast) in moderate to extreme drought (based on the Palmer Drought Index) decreased slightly compared to last month to about 10.6 percent due to more contraction in the Northwest than expansion in the Southwest. The area of the West experiencing moist conditions dropped to 4.4 percent at the end of November.
- Abnormal dryness (D0) to extreme (D3) drought continued in the central to southern Plains. Much of Kansas and Texas have been drier than normal for the last 1 to 3 months, and even longer (out to the last 12 months in parts of Texas). Dryness is reflected in several indicators, including some streams, the GRACE groundwater indicator, soil moisture indicators (NLDAS top soil and total soil moisture model, CPC soil moisture model, GRACE satellite-based estimations of surface soil moisture and root zone soil moisture, SMOS satellite observations), and vegetation-based indicators (QuickDRI). In Texas, according to USDA reports, 45 percent of the pasture and rangeland was in poor to very poor condition, and 50 percent of topsoil moisture and 50 percent of subsoil moisture was rated short to very short. In Kansas, 14 percent of the pasture and rangeland was in poor to very poor condition, and 40 percent of topsoil moisture and 36 percent of subsoil moisture was short to very short.
- Extreme drought disappeared and moderate to severe drought contracted considerably in the Southeast. Altogether, drought shrank from 40.7 percent of the region at the end of October to 9.9 percent by the end of November. The contraction occurred in most areas except southern Florida, where abnormal dryness and drought expanded. Dryness was still reflected in several indicators, including groundwater estimations, soil moisture indicators (NLDAS top soil and total soil moisture model, CPC soil moisture model, GRACE satellite-based estimations of surface soil moisture and root zone soil moisture, SMOS satellite observations), and some streams.
- Abnormal dryness lingered in the Mid-Atlantic region (Virginia to New Jersey), reflecting dry conditions in indicators such as groundwater estimations, streamflow observations, vegetation-based indicators (QuickDRI), soil moisture indicators (NLDAS top soil and total soil moisture model, CPC soil moisture model, GRACE satellite-based estimations of surface soil moisture and root zone soil moisture).
- Severe drought was eliminated and abnormal dryness to moderate drought contracted in Alaska.
- In Hawaii, abnormal dryness to extreme drought continued, with about 16.4 percent of the state in drought (D1-D3) and 64.5 percent experiencing abnormally dry conditions or drought (D0-D3).
- Moderate drought returned to eastern Puerto Rico, while abnormal dryness developed on St. John and moderate drought continued on St. Croix in the U.S. Virgin Islands.
- In the U.S.-Affiliated Pacific Islands (USAPI), abnormal dryness continued in parts of the Federated States of Micronesia.
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 (as well as wet spell conditions) in some 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.
Used together, the Palmer Z Index and PHDI maps show that short-term drought occurred across the Pacific Northwest and into adjacent parts of California and the Great Basin. The persistence of short-term dry conditions expanded long-term drought along the Pacific Northwest coast during November compared to October, and shrank long-term wet conditions in the Great Basin. Short-term drought occurred in parts of the Mid-Atlantic coast and in southern Florida, expanding long-term drought. Short-term drought in east Texas and the western Gulf Coast shrank long-term wet conditions. Short-term wet conditions in the Southwest and near-normal to wet conditions during November in the Southeast shrank long-term drought in those regions (November vs. October).
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 SPI maps illustrate how moisture conditions have varied considerably through time and space over the last two years. The Pacific Northwest and adjacent parts of the Great Basin and northern California are very dry at the 1- to 6-month time scales, with smaller parts of the Pacific Northwest dry at the 9- to 24-month time scales. Much of the Southwest (Four Corners area) is very dry at 6 months, with smaller parts less dry at the 2-, 3-, 9-, and 24-month time scales. Much of the Gulf of Mexico Coast is dry at 1 month, with parts of Texas dry at 3 to 12 months. Parts of the central Plains (Kansas) have significant dryness at the 3- to 6-month time scales. Much of Florida is dry at 3 months. Parts of the southern Great Lakes are dry at 1 and 3 months. Parts of the Mid-Atlantic are dry at 1 and 3 to 12 months, with dryness extending into coastal New England at 1 month. Otherwise, wet conditions dominate much of the country east of the Rockies for the last 2 and 6 to 24 months.
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.
Temperatures during November 2019 were warmer than normal in the Southwest, and near to warmer than normal in the Pacific Northwest. But temperatures were near to cooler than normal, especially in the Northwest, for much of the last 12 months (last 3, 4, 11, 12 months). As a result, for the dry areas of the West, the SPEI values were similar in magnitude to the SPI values for this period (SPEI maps for last 1, 3, 6, and 12 months) (SPI maps for last 1, 3, 6, and 12 months).
But for the previous six years, excessive heat dominated much of the West, with temperatures at record to near-record levels. The heat, especially during the summer, increased evapotranspiration and exacerbated the dry conditions which occurred from California to the central Rockies and in the Pacific Northwest. This is seen in a more extreme SPEI compared to SPI during this period (SPEI maps for last 24, 36, 48, 60, 72 months) (SPI maps for last 24, 36, 48, 60, 72 months).
Regional Discussion
November 2019 was drier than normal across much of the Hawaiian Islands. Generally drier-than-normal conditions were observed more often than wetter-than-normal conditions for most of the time periods over the last year (last 1, 2, 3, 4, 5, 6, 8, 9, 11, 12 months). Wetter-than-normal conditions dominated at longer time periods (last 24, 36, 48, 60 months). Streamflow was below normal at streams in the central islands, and near to above normal across the Big Island and Kauai. Drought and abnormal dryness expanded in some areas but contracted in more areas. The statewide drought area increased slightly from 14.9 percent of Hawaii at the end of October to 16.4 percent at the end of November. Moderate to extreme drought remained on the December 3rd USDM map.
Gridded precipitation percentile map for Alaska, January-November 2019.
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Alaska precipitation anomaly map, November 2019.
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November 2019 was wetter than normal across most of Alaska. The wet conditions helped contract drought in the south coastal and panhandle areas. But drier-than-normal conditions at longer time scales kept abnormal dryness and moderate drought in these southern areas (low elevation station precipitation anomaly maps for the last 1, 2, 3, 4, 5, 6, 8, 9, 11, 12, 24, 36, 48, 60 months) (gridded precipitation percentile maps for the last 1, 3, 11 months) (climate division precipitation rank maps for the last 1, 3, 6, 11, 12 months) . Temperatures during November were warmer than normal across the state, with record warmth occurring in some areas, especially in the south. Warmer-than-normal conditions to record warmth dominated the state at longer time scales (low elevation station temperature maps for the last 1, 2, 3, 4, 11, 12 months) (gridded temperature percentile maps for the last 1, 3, 11 months) (climate division temperature rank maps for the last 1, 3, 6, 11, 12 months). . Snow pack was below average at the southern SNOTEL stations due to the warm temperatures. Streamflow was generally above normal due to the above-normal precipitation. Abnormally dry and moderate drought conditions contracted this month, with severe drought ending. The drought area contracted from 4.0 percent of the state at the end of October to 0.8 percent on the December 3rd USDM map. A new maximum drought duration record was set for the state — moderate drought began on July 17, 2018 and has continued to the latest map (dated December 3, 2019), lasting (so far) 73 weeks.
Puerto Rico percent of normal precipitation map for November 2019.
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Puerto Rico and the U.S. Virgin Islands percent of normal precipitation map for October-November 2019.
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Puerto Rico and U.S. Virgin Islands:
The U.S. Virgin Islands (USVI) and eastern Puerto Rico were drier than normal during November. Drier-than-normal conditions generally persisted across the USVI and became more widespread across southwestern to northeastern Puerto Rico in 2019 at longer time scales. Puerto Rico and the USVI were drier than normal at 12 to 24 months, while wetter-than-normal conditions dominated at longer time scales (radar-based precipitation anomaly estimates for the last 1, 2, 3, 6, 11, 12 months) (low elevation station precipitation maps for the last 1, 2, 3, 4, 6, 8, 9, 11, 12, 24, 36, 48, 60 months). Soil conditions improved in southwestern Puerto Rico but soils in parts of the east were still dry. November streamflow was below normal across most of eastern Puerto Rico. Moderate drought returned to eastern Puerto Rico during November, covering 15.5 percent of the island as seen on the December 3rd USDM map. Abnormal dryness and drought covered 39.7 percent of the island at the end of November compared to 30.6 percent abnormally dry at the end of October. In the USVI, moderate drought continued on St. Croix and abnormal dryness developed on St. John, with St. Thomas continuing free of drought and abnormal dryness.
CONUS State Precipitation Ranks:
November 2019 was drier than normal across the Pacific Northwest into adjacent northern California and the Great Basin, from the central Plains to southern Great Lakes, much of Texas and the Gulf Coast states, and from the Mid-Atlantic to coastal New England. Fifteen states had a rank in the driest third of the 125-year historical record for November, including three in the top ten driest category. These included the fifth driest on record for Idaho and Washington, and seventh driest for Oregon.
The dryness in the Pacific Northwest, northern California, and adjacent Great Basin extended across the fall (September-November). It was also dry from the Four Corners region to central Plains and across much of Texas and parts of the Southeast, Ohio Valley, and Mid-Atlantic region. Ten states had a rank in the driest third of the 1895-2019 historical record for September-November, including Florida which ranked 13th driest.
The last six months (June-November) were drier than normal across most of the West and Texas, and parts of Kansas, the Southeast, and Mid-Atlantic regions. Eleven states had a rank in the driest third of the historical record, including California and Oregon which ranked 13th driest.
The year to date (January-November) was drier than normal across parts of the Pacific Northwest, Southwest into Texas, and Southeast. Four states ranked in the driest third of the historical record, including one in the top ten driest category — Washington at eighth driest. A similar precipitation anomaly pattern existed for the last 12 months (December 2018-November 2019), but not as extensive or severe, with only one state ranking in the driest third of the historical record (Washington at 15th driest).
Primary Hard Red Winter Wheat Belt precipitation, November, 1895-2019.
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Primary Hard Red Winter Wheat Belt precipitation, October-November, 1895-2019.
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During November 2019, the Primary Hard Red Winter Wheat agricultural belt was near to cooler than normal and much of it was drier than normal. The month ranked as the 62nd driest (64th wettest) and 44th coolest November, regionwide, in the 1895-2019 record.
October marks the beginning of the growing season for the Primary Hard Red Winter Wheat agricultural belt. October-November 2019 was colder than normal with precipitation mostly drier than normal with some wetter-than-normal areas. The 2-month period ranked as the 59th wettest and 13th coldest October-November, regionwide, in the 1895-2019 record.
As of December 3rd, drought affected approximately ten percent of winter wheat production, nine percent of cattle inventory, seven percent of hay acreage, two percent of corn production, and one percent of soybean production. None of the spring wheat producing areas were in a drought status as of December 3.
NOAA Regional Climate Centers:
More information, provided by the NOAA Regional Climate Centers and others, can be found below.
As summarized by the High Plains Regional Climate Center, temperatures across much of the High Plains were generally near normal for the month of November, with wet and snowy conditions in portions of the region, especially late in the month. The month started off very dry for much of the region as the High Plains continued its relatively dry streak that began in late October. Despite the dryness, two large systems that came through in the latter part of the month brought enough precipitation to compensate for the dryness experienced early in the month in some places. Drought conditions continued to expand across portions of Kansas and Colorado during the month, where precipitation remained well below normal.
Mountain snowpack got off to a good start this month across all of Colorado and much of Wyoming. This has helped keep drought conditions from worsening and lowers concerns for low water levels. By the end of November snowpack was above normal across all of the basins in Colorado and almost all of the basins in Wyoming. Across the Upper Missouri Basin, mountain Snow Water Equivalent (SWE) was near to slightly above normal.
Drought conditions continued to expand and intensify across southern and western portions of the High Plains region during the month of November. According to the USDM, the area experiencing drought (D1-D4) in the High Plains region increased from approximately 13 percent at the end of October to just over 15 percent by the end of November. This increase included the expansion of drought in areas of southern and western Colorado and southwestern Kansas where precipitation deficits have continued to worsen over the past several months. This month, abnormally dry conditions (D0) continued to expand across portions of western Kansas and into portions of southwestern Nebraska. D0 remained nearly unchanged in parts of southwestern Wyoming. Some improvement was observed over northern Colorado during the month, with a reduction of abnormally dry conditions in this area. Meanwhile, across southern Colorado and western Kansas, moderate drought (D1) expanded through the month of November, while severe drought (D2) also expanded across some portions of this same area. A small pocket of extreme drought (D3) also developed across southwestern Kansas during the month. The remainder of the region was free of drought and abnormally dry conditions. As of the November 26th release of the USDM, both Nebraska and South Dakota continued their streak of being drought-free all of 2019.
Crop harvest remained well behind schedule across the northern areas of the High Plains region. Even with the help of drier conditions, especially during the first half of the month, farmers across North Dakota and South Dakota continued to struggle getting their crops out of the ground. Particularly hard hit were sugar beets, sunflowers, and corn. As of December 1st, only 36 percent of corn had been harvested in North Dakota, and 80 percent in South Dakota. Sunflower harvest was at 51 percent in North Dakota and 71 percent in South Dakota as of December 1st. The wet and snowy pattern that began in October led to incredibly wet soils that were too muddy or inundated to be able to harvest crops. Only as consistently colder temperatures began to freeze and harden the soil were some agriculture producers able to get back into the fields to harvest their crops. It is likely that some crops will not get harvested until spring, or perhaps not harvested at all, due to poor field conditions.
As explained by the Southern Regional Climate Center, temperatures for the month of November were below normal across the Southern region and precipitation was primarily below normal. Parts of northern Oklahoma, southern Arkansas, southern and western Mississippi, northern, western, southern, and southeastern Louisiana, and eastern, central, and southern Texas received 50 percent or less of normal precipitation, while parts of western, southern, and southeastern Louisiana as well as eastern, central, and southern Texas received 25 percent or less of normal precipitation. In contrast, parts of north-central, western, and southern Texas; northern Arkansas, and eastern Tennessee received 150 percent or more of normal precipitation, while parts of north-central, southern, and western Texas received precipitation 200 percent or more of normal.
At the end of November, drought conditions both improved and deteriorated across the Southern region. Extreme drought conditions persisted across southern Texas, while areas in central and southern Texas experienced improvement. Severe drought classifications were still present in central and southern Texas as well as southwestern Oklahoma, while new areas developed in extreme western Oklahoma. However, severe drought conditions improved across eastern and southern Texas, and these conditions were removed in southeastern Tennessee. Moderate drought classifications decreased across eastern, central, and southern Texas; southwestern Arkansas, northwestern and northeastern Louisiana, and southeastern Tennessee, while new areas developed in extreme western and southwestern Oklahoma as well as northern and eastern Texas. There was an increase in the overall area experiencing abnormally dry conditions despite improvement across central Arkansas, southwestern Mississippi, and eastern Tennessee. This was due to an increase in abnormally dry conditions across western and southwestern Oklahoma; northern, western, and eastern Texas; and southwestern Arkansas.
As described by the Midwest Regional Climate Center, November temperatures averaged below normal across the Midwest and November precipitation had alternating bands of above- and below-normal precipitation. Two bands of above-normal precipitation stretched from west to east, one from southern Missouri to Kentucky and the other from the Iowa-Minnesota border to northern and central Michigan. Two bands of below-normal precipitation stretched from much of Missouri and Iowa into northern Ohio and from northern and central Minnesota into northern Wisconsin. Regionwide the precipitation averaged 2.26 inches (57.4 mm) which was 0.52 inch (13.2 mm) below normal. Fall (September to November) precipitation was well above normal in the northern half of the region and mostly near normal in the southern half. Snowfall in November was above normal across most of the Midwest and well above normal in the southeastern half of the region.
Moderate drought areas in the southeastern Midwest at the end of October were reduced and then eliminated by the November 12th USDM. By the end of November, only a small area of southeastern Kentucky was considered abnormally dry and that area was also eliminated as of the December 3rd USDM.
The slow harvest season continued well into November in the Midwest as the impacts of a delayed planting season continued. The soybean harvest neared completion by mid-November, but corn harvesting was 10 to 30 percent behind the five-year average by mid-month in every state except Kentucky according to USDA NASS. By the end of November, a third of the corn crop remained unharvested in Wisconsin and Michigan. Increased snowfall in the Upper Midwest hampered progress, while drier weather across the central Corn Belt allowed much of the harvest to wrap up by the end of the month.
As noted by the Southeast Regional Climate Center, temperatures were near average to above average in Florida and Puerto Rico during November, while below-average temperatures were observed across Alabama, Georgia, the Carolinas, and Virginia. November precipitation was variable across much of the Southeast region. Unusual dryness was found in northern Virginia, western North Carolina, southern Alabama, and parts of the Florida Panhandle, where the precipitation values ranged from 70 to less than 25 percent of normal. Niceville, FL (1927-2019) reported only 0.96 inch (24 mm) of precipitation for the month, which was about 4 inches (102 mm) below normal. Puerto Rico also reported below normal precipitation, with Guayama (1911-2019) only observing 1.7 inches (43 mm) of rain.
Overall drought conditions have improved for the month of November, with no areas of extreme drought (D3). By the end of the month, pockets of severe drought (D2) were observed in northern Georgia. Moderate drought (D1), ringed by an area of dry conditions (D0), decreased in coverage through western South Carolina, Georgia, central Alabama and northern Florida. Drought conditions were gone from Virginia and North Carolina, however abnormally dry conditions (D0) were reported throughout the interior of each state. Puerto Rico continues to have an area of dry conditions (D0) covering the southern area. Citrus-producing counties in Florida received little to no rainfall, as abnormally dry conditions covered the complete southern part of the state. Therefore, irrigation was run across this citrus growing region. In North Carolina, the harvest has been completed for most crops, though wet weather and high seed moisture content has slowed the field work. The early November freeze in Moore County, NC has damaged some of the recently planted strawberries. Farmers in Georgia are worried that there will not be enough hay due to the autumn drought, which caused some to feed early. The rains in November have provided better winter grazing for pastures in Alabama.
As explained by the Northeast Regional Climate Center, November was a drier-than-normal month in the Northeast and ranked 15th coldest for temperature regionwide. The region received 2.92 inches (74.17 mm) of precipitation, which was 76 percent of normal. The Northeast experienced a dry September and November but a wet October. With that, the region averaged 10.98 inches (278.89 mm) of precipitation for autumn, which was 95 percent of normal. The USDM released on November 7 showed lingering areas of abnormal dryness in West Virginia, Maryland, Delaware, southern Pennsylvania, New Jersey, and southeastern New York, totaling 5 percent of the Northeast. During November, dryness eased in New York and continued to improve in the other states. The USDM released on November 27 showed 2 percent of the region as abnormally dry.
As summarized by the Western Regional Climate Center, November was drier than normal for the Pacific Northwest extending south into northern California and Nevada. For much of the southern part of the region precipitation was well above normal with exceptionally wet conditions in southeast California, southern Nevada, Arizona and New Mexico. Temperatures were above normal across most of the region with the greatest departures observed in the higher elevations of the Sierra Nevada and Cascades due to extended periods of high pressure causing strong temperature inversions. Locations east of the Rocky Mountains experienced below-normal temperatures for the month.
High pressure centered off the central coast of British Columbia persisted throughout the month causing below-normal precipitation in the Pacific Northwest. Record dryness occurred in Boise, Idaho with only 0.12 inches (3 mm; 9% of normal) of precipitation observed, which broke the record dating back to 1940. Seattle, Washington, where November is the wettest month of the year, logged 1.71 inches (43.4 mm; 26% of normal) of precipitation making it the 4th driest November since 1945. Likewise, the lack of precipitation led to below normal snowpack accumulations across parts of the Cascades where the snow water equivalent (SWE) was record low for the end of the month. Park Creek Ridge SNOTEL in the Upper Columbia River Basin, Washington, set a record low on November 30 with a SWE value of 1.2 inches (30.5 mm; 13% of normal) with measurements beginning in 1977.
In Alaska, above-normal temperatures persisted across the entire state. Off the northwest coast of Alaska, the Chukchi Sea ice extent was the lowest on record for the month of November. For the Hawaiian Islands, most of the island chain saw below-average monthly precipitation with the exception of Kauai where many stations were 100-125% of normal. Maui was the driest of the islands where only 0.21 inch (5.3 mm) of precipitation was recorded at Kahului Airport, 10% of normal and the 6th driest on record. The continued dryness in Hawaii led to large areas of moderate to extreme drought in the USDM at the end of November.
U.S.-Affiliated 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), November 2019 was drier-than-normal at Koror; Chuuk, Kosrae, and Lukonor (in the FSM); and Pago Pago; November was wetter than normal at the rest of the primary stations.
Monthly precipitation amounts were below the monthly minimum needed to meet most water needs (4 inches in the Marianas and Pago Pago, and 8 inches elsewhere) at Lukonor (in the FSM), and above the monthly minimums at the rest of the USAPI stations. The 4- and 8-inch thresholds are important because, if monthly precipitation falls below the threshold, then water shortages or drought become a concern.
Station Name | Dec 2018 | Jan 2019 | Feb 2019 | Mar 2019 | Apr 2019 | May 2019 | Jun 2019 | Jul 2019 | Aug 2019 | Sep 2019 | Oct 2019 | Nov 2019 | Dec- Nov |
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Chuuk | 76% | 183% | 122% | 175% | 48% | 42% | 125% | 97% | 125% | 135% | 48% | 87% | 98% |
Guam NAS | 152% | 106% | 228% | 39% | 45% | 77% | 46% | 46% | 135% | 166% | 93% | 214% | 99% |
Kapingamarangi | 93% | 195% | 44% | 197% | 127% | 169% | 172% | 110% | 124% | 55% | 142% | 229% | 123% |
Koror | 111% | 96% | 40% | 84% | 94% | 57% | 93% | 81% | 140% | 74% | 118% | 99% | 85% |
Kosrae | 49% | 93% | 98% | 143% | 137% | 152% | 103% | 62% | 117% | 69% | 98% | 98% | 86% |
Kwajalein | 99% | 49% | 183% | 52% | 22% | 159% | 69% | 48% | 104% | 92% | 94% | 111% | 87% |
Lukonor | 70% | 148% | 71% | 103% | 126% | 32% | 127% | 104% | 96% | 63% | 51% | 66% | 78% |
Majuro | 112% | 93% | 74% | 102% | 35% | 160% | 103% | 64% | 109% | 105% | 117% | 110% | 99% |
Pago Pago | 176% | 83% | 200% | 107% | 108% | 154% | 117% | 316% | 160% | 81% | 105% | 74% | 119% |
Pohnpei | 100% | 134% | 79% | 143% | 66% | 45% | 159% | 101% | 110% | 155% | 138% | 168% | 111% |
Saipan | 137% | 70% | 59% | 28% | 35% | 243% | 58% | 76% | 140% | 218% | 169% | 126% | 128% |
Yap | 125% | 249% | 30% | 107% | 52% | 91% | 109% | 81% | 78% | 65% | 70% | 105% | 89% |
Station Name | Dec 2018 | Jan 2019 | Feb 2019 | Mar 2019 | Apr 2019 | May 2019 | Jun 2019 | Jul 2019 | Aug 2019 | Sep 2019 | Oct 2019 | Nov 2019 | Dec- Nov |
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Chuuk | 8.53" | 18.49" | 8.87" | 14.56" | 6.00" | 4.74" | 14.62" | 11.65" | 16.13" | 15.81" | 5.55" | 9.26" | 134.21" |
Guam NAS | 7.75" | 4.24" | 6.90" | 0.81" | 1.15" | 2.61" | 2.85" | 4.63" | 19.92" | 21.03" | 10.59" | 15.76" | 98.24" |
Kapingamarangi | 9.13" | 17.87" | 4.06" | 22.56" | 17.33" | 20.46" | 23.68" | 15.52" | 10.11" | 5.50" | 11.67" | 21.27" | 179.16" |
Koror | 12.37" | 9.79" | 3.45" | 6.24" | 6.89" | 6.78" | 16.30" | 15.04" | 18.91" | 8.74" | 13.94" | 11.29" | 129.74" |
Kosrae | 7.92" | 15.58" | 12.62" | 23.02" | 23.96" | 26.91" | 15.08" | 9.19" | 16.61" | 9.78" | 10.69" | 13.55" | 184.91" |
Kwajalein | 6.58" | 1.54" | 4.82" | 1.22" | 1.14" | 10.71" | 4.76" | 4.77" | 10.10" | 9.89" | 10.53" | 12.52" | 78.58" |
Lukonor | 7.89" | 12.41" | 6.33" | 9.58" | 14.30" | 3.75" | 14.80" | 16.63" | 13.47" | 6.44" | 5.79" | 6.01" | 117.4" |
Majuro | 12.71" | 7.23" | 5.09" | 6.74" | 3.34" | 16.14" | 11.31" | 7.12" | 12.69" | 11.73" | 14.95" | 14.83" | 123.88" |
Pago Pago | 22.59" | 11.10" | 24.04" | 11.47" | 10.17" | 14.91" | 6.24" | 17.54" | 8.60" | 5.28" | 9.71" | 7.48" | 149.13" |
Pohnpei | 16.13" | 17.68" | 7.57" | 18.84" | 12.23" | 8.94" | 23.56" | 15.64" | 15.74" | 19.47" | 21.01" | 24.91" | 201.72" |
Saipan | 5.28" | 1.76" | 1.54" | 0.53" | 0.93" | 5.78" | 2.11" | 6.73" | 18.32" | 21.99" | 17.92" | 7.06" | 89.95" |
Yap | 10.68" | 15.90" | 1.57" | 4.88" | 2.92" | 7.15" | 13.14" | 12.25" | 11.58" | 8.82" | 8.54" | 9.30" | 106.73" |
Station Name | Dec 2018 | Jan 2019 | Feb 2019 | Mar 2019 | Apr 2019 | May 2019 | Jun 2019 | Jul 2019 | Aug 2019 | Sep 2019 | Oct 2019 | Nov 2019 | Dec- Nov |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Chuuk | 11.25" | 10.10" | 7.25" | 8.32" | 12.47" | 11.30" | 11.66" | 11.98" | 12.86" | 11.71" | 11.51" | 10.61" | 136.77" |
Guam NAS | 5.11" | 4.01" | 3.03" | 2.07" | 2.53" | 3.40" | 6.18" | 10.14" | 14.74" | 12.66" | 11.44" | 7.38" | 99.09" |
Kapingamarangi | 9.84" | 9.15" | 9.27" | 11.43" | 13.64" | 12.08" | 13.78" | 14.15" | 8.13" | 9.93" | 8.19" | 9.27" | 145.85" |
Koror | 11.16" | 10.18" | 8.56" | 7.44" | 7.32" | 11.83" | 17.48" | 18.53" | 13.50" | 11.77" | 11.84" | 11.39" | 152.90" |
Kosrae | 16.11" | 16.67" | 12.93" | 16.06" | 17.51" | 17.75" | 14.64" | 14.91" | 14.22" | 14.22" | 10.94" | 13.83" | 213.87" |
Kwajalein | 6.66" | 3.16" | 2.64" | 2.35" | 5.26" | 6.72" | 6.93" | 9.87" | 9.74" | 10.74" | 11.18" | 11.28" | 90.41" |
Lukonor | 11.27" | 8.41" | 8.93" | 9.26" | 11.31" | 11.69" | 11.65" | 15.93" | 14.04" | 10.15" | 11.32" | 9.08" | 151.36" |
Majuro | 11.39" | 7.74" | 6.88" | 6.58" | 9.42" | 10.11" | 11.01" | 11.17" | 11.69" | 11.17" | 12.73" | 13.44" | 125.25" |
Pago Pago | 12.84" | 13.34" | 12.00" | 10.68" | 9.39" | 9.66" | 5.33" | 5.55" | 5.38" | 6.53" | 9.26" | 10.14" | 125.57" |
Pohnpei | 16.08" | 13.18" | 9.55" | 13.17" | 18.41" | 19.96" | 14.81" | 15.43" | 14.26" | 12.55" | 15.27" | 14.83" | 182.36" |
Saipan | 3.85" | 2.53" | 2.59" | 1.89" | 2.63" | 2.38" | 3.62" | 8.91" | 13.13" | 10.09" | 10.62" | 5.61" | 70.25" |
Yap | 8.51" | 6.39" | 5.19" | 4.56" | 5.63" | 7.85" | 12.04" | 15.08" | 14.82" | 13.50" | 12.18" | 8.83" | 120.31" |
As measured by percent of normal precipitation, Lukonor was drier than normal in the short term (November and the last 3 months [September-November 2019]) and long term (year to date [January-November] and last 12 months [December 2018-November 2019]). Koror, Kosrae, and Yap were near to wetter than normal for November but drier than normal for the other 3 time scales. Chuuk and Pago Pago were drier than normal in the short-term and near or wetter than normal in the long-term. Kwajalein and Majuro were wetter than normal in the short-term and near to drier than normal in the long-term. Guam, Kapingamarangi, Pohnpei, and Saipan were near to wetter than normal at all 4 time scales. It should be noted that the monthly normal precipitation amount can vary significantly from month to month due to the strong seasonality of equatorial Pacific precipitation resulting from the seasonal migration of the Inter-Tropical Convergence Zone (ITCZ).
Percent of normal precipitation map for November 2019 for the Marianas Islands.
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Percent of normal precipitation map for November 2019 for the Marshall Islands.
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In the Marianas Islands, precipitation was wetter than normal regionwide for November. Abundant rainfall during recent months has resulted in a wetter-than-normal precipitation anomaly pattern for the last one to five months, and a generally wetter-than-normal pattern for most of the last five years (percent of normal precipitation maps for the last 1, 2, 3, 4, 5, 6, 8, 9, 11, 12, 24, 36, 48, 60 months). In the Marshall Islands, November precipitation was wetter than normal at most stations, as was the 2-month period. At longer time scales, more and more stations have drier-than-normal conditions until most stations are drier than normal at the 8- to 12-month time scales. A mixed pattern is evident at multi-year time scales (percent of normal precipitation maps for the last 1, 2, 3, 4, 5, 6, 8, 9, 11, 12, 24, 36, 48 months).
According to the November 30th USDM produced for the USAPI, abnormal dryness (D0) persisted at only Lukonor and Woleai in the FSM. Storage in the Majuro reservoirs fluctuated up and down during November, starting at 30.3 million gallons at the beginning of the month, falling to 28.1 million gallons on the 13th, peaking at 31.8 million gallons on the 22nd, and ending the month at 29.8 million gallons, or about 83 percent of maximum, which is above the 80 percent threshold for concern.
The abundant rainfall in November 2019 in parts of Micronesia resulted in the second wettest November on record for Mili and Utirik, third wettest for Kapingamarangi, fourth wettest for Pohnpei, and fifth wettest for Guam. But the dryness in other parts led to low precipitation ranks for Lukonor (sixth driest), Pago Pago (12th driest), and Woleai (19th driest). Persistent dryness at several stations resulted in dry multi-month ranks. Lukonor had the driest September-November, August-November, and May-November; Woleai and Yap had the second driest July-November; Nukuoro had the fifth driest May-November; Chuuk had the seventh driest April-November; Ailinglapalap had the eighth driest April-November and March-November; and Kwajalein had the eighth driest June-November and December-November. (It should be noted that there may have been an undercatch issue with Jaluit's rain gauge earlier in 2019.)
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 November 2019, June-November 2019 (last 6 months), and December 2018-November 2019 (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 of 1 = driest.
Station | Nov 2019 Rank |
Nov No. of Years |
Jun- Nov 2019 Rank |
Jun- Nov No. of Years |
Dec 2018- Nov 2019 Rank |
Dec- Nov No. of Years |
Period of Record |
Pago Pago | 12 | 54 | 36 | 54 | 47 | 53 | 1966-2019 |
Saipan | 31 | 39 | 38 | 39 | 28 | 30 | 1981-2019 |
Kapingamarangi | 29 | 31 | 18 | 18 | 16 | 17 | 1962-2019 |
Kosrae | 24 | 52 | 9 | 39 | 13 | 32 | 1954-2019 |
Lukonor | 6 | 36 | 3 | 23 | 6 | 23 | 1981-2019 |
Nukuoro | 15 | 36 | 17 | 35 | 8 | 34 | 1981-2019 |
Pingelap | MSG | 35 | MSG | 34 | MSG | 32 | 1981-2019 |
Woleai | 19 | 36 | 5 | 27 | 5 | 24 | 1968-2019 |
Yap | 34 | 69 | 8 | 68 | 15 | 68 | 1951-2019 |
Pohnpei | 66 | 69 | 65 | 68 | 50 | 68 | 1951-2019 |
Chuuk | 27 | 69 | 28 | 68 | 25 | 68 | 1951-2019 |
Guam | 59 | 63 | 41 | 63 | 30 | 62 | 1957-2019 |
Koror | 38 | 69 | 32 | 67 | 15 | 67 | 1951-2019 |
Ailinglapalap | 26 | 36 | 13 | 35 | 9 | 33 | 1981-2019 |
Jaluit | 30 | 36 | 2 | 35 | 2 | 33 | 1981-2019 |
Mili | 35 | 36 | 32 | 34 | 27 | 32 | 1981-2019 |
Utirik | 17 | 18 | 5 | 8 | 1 | 4 | 1985-2019 |
Wotje | 25 | 35 | 27 | 34 | 16 | 31 | 1981-2019 |
Kwajalein | 45 | 68 | 8 | 68 | 8 | 67 | 1952-2019 |
Majuro | 43 | 66 | 27 | 66 | 24 | 65 | 1954-2019 |
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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.):
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