California and National Drought Summary for June 16, 2015
East-Central States
A swath of dryness has developed during the last couple of months from the interior eastern Carolinas northwestward through the lower Ohio Valley, including most of Kentucky, northeastern Tennessee, and southwestern West Virginia. Last week continued the pattern, with most of the region measuring 0.5 inch rain or less.Growing moisture shortages prompted broad deterioration through the lower Ohio Valley, much of Kentucky, and adjacent West Virginia and Tennessee, including the introduction of moderate drought in the immediate lower Ohio Valley, eastern Kentucky and Tennessee, and adjacent West Virginia. In addition, D0 also expanded a bit eastward in the interior eastern Carolinas. The areas in moderate drought have received generally one-third to two-thirds of normal rainfall since mid-April.
Great Plains
Only a few areas of dryness and drought remain in the Great Plains following the deluges of the last 1 to 2 months. It was wet again this past week, with most sites from the western Dakotas and northern Nebraska southward through central and southeast Texas recording at least an inch of rain. The heaviest amounts (2 to over 6 inches) fell on portions of upper southeast Texas, and in a broad swath from northwestern Texas and most of Oklahoma northeastward through southern and east-central Kansas and eastern Nebraska.D1 and D0 coverage again declined as a result, with improvements in southwest Kansas and parts of the Oklahoma and Texas Panhandles. Despite the heavy rains in what is now the driest part of the Plains (southeastern South Dakota and northeastern Nebraska), satellite-derived estimates still showed low levels of groundwater and root zone moisture, and vegetative health remained stressed by dryness. As a result, no changes were made this week.
There were also no changes in the other regions of dryness in the Plains, where the week’s weather was relatively nondescript.
Hawaii, Alaska, and Puerto Rico
Leeward areas of Hawaii have been drying out in recent weeks, particularly in the western half of the state, while windward areas have received adequate rainfall. The leeward dryness did lead to the introduction of D0 on north Kauai, and a slight northeastward expansion of D0 and D1 areas on Oahu.Subnormal rainfall this past week kept the dryness and drought on Puerto Rico intensifying and expanding. Streamflow percentiles are in the low single digits in central and eastern parts of the island. This week, D0 expanded westward along the northern tier of the state; part of central Puerto Rico slipped into moderate drought, as did both northeastern and southeastern parts of the state; and severe drought expanded westward toward the central interior, almost doubling in size from last week.
Up to 2 inches of precipitation fell along the southern coast and the Panhandle of Alaska, but most of the abnormally dry region reported only 0.25 to 0.50 inch of precipitation, with slightly higher amounts in the north-central part of the state.
A number of wildfires have broken out in central and west-central Alaska (in addition to parts of the extant D0 area), and fire danger remains extremely high. Little or no precipitation fell this past week. As a result, D0 was expanded through central and east-central sections of AK.
Midwest and Great Lakes Region
Beneficial rains fell on the D0 area in the eastern Great Lakes, but in deference to longer-term deficits and low groundwater estimates, no changes were made this week. Generally 3 to 5 inches soaked south-central Michigan, and only part of east-central Michigan and northeast Indiana reported less than 2 inches. Precipitation totals are now near to above normal for the last 6 months, but parts of the region still reports somewhat below normal precipitation for the past 9 to 24 months, with northeast Indiana having subnormal totals for the longest period. This, in addition to satellite estimates of groundwater levels are in the driest 5 to 20 percent of historic occurrences.Northern Minnesota and adjacent Wisconsin received little or no rain this past week, with dryness essentially unchanged in intensity.
The Northeast
A variable precipitation pattern was observed across the Northeast. Most of central and north New York and western New England received 2 to 4 inches of rain over the course of the week. In contrast, many locations in southern and eastern Pennsylvania, lower New York and Long Island, and east New England reported 0.5 to 1.0 inch.For most areas experiencing dryness and drought, rainfall was not sufficiently anomalous (nor widespread) to improve or worsen conditions, and no changes were made in the Drought Monitor. The only exceptions were two areas of D0 in the northwestern tier of New York, where the moderate to locally heavy rains ended the regions’ dryness.
For the past 6 months, precipitation shortages of 5 to 10 inches have accumulated in much of central and southern New England, and significant deficits date back a couple of years in most of a swath from central and north-central Pennsylvania eastward through southern New England.
The Rockies To The West Coast
Unseasonably heavy rains fell again this week across a swath from west-central Nevada through portions of Utah, southernmost Idaho, western Wyoming, southwestern Colorado, and adjacent Arizona and New Mexico, partially from tropical cyclone remnants. The rains of the current and past few weeks led to some broad areas of improvement, most notably interior west-central Nevada (to D3), northeastern Nevada and adjacent Idaho and Utah (to D0 in one area), and a broad portion of the Four Corners region. Farther north and west, however, dryness and warmth led to degradations in part of western Oregon, northern Idaho and adjacent Montana, and a few other small patches.Although this week finally brought an end to the protracted period of D4 conditions entrenched in west-central Nevada, it should be noted that water supplies were practically unaffected by the recent precipitation, remaining alarmingly low. Cutbacks in water availability were not changed, and thus agriculture (which is irrigated) continued to suffer without respite. However, amounts were so unusual that precipitation totals for the last 2 years have moved near to above normal in part of the region. As a result the landscape is looking greener than it has in a long time, and across the state, only 25% of pastureland was short or very short of moisture, the lowest total since October 2011.
The Southeast
Rainfall totals were somewhat higher in this region than in the areas to the north, but above-normal amounts were patchy, and this in combination with abnormally high temperatures resulted in more areas of deterioration than improvement.The swaths of D0 from eastern Mississippi northeastward into northwestern Georgia changed shape a bit in response to spotty areas that received either significantly more (2 to locally 5 inches) or less (under 0.5 inch) than the amounts that prevailed across the region. Across this general area, dryness and drought could expand and intensify quickly if deficient rainfall and abnormally hot weather predominate over the next few weeks.
Across the southern tier of Georgia and northern Florida, generally 0.5 to 2.0 inches of rain was reported, along with warmer than normal conditions. As a result, dryness and drought expanded in areas reporting totals in the lower end of the range (primarily southeastern Georgia, northeastern Florida, and eastern parts of the Florida Panhandle). In both D1 areas, 60-day totals are generally 2 to 5 inches below normal.
In south Florida, drier than normal conditions prevailed near the southeastern coast, but farther north 2 to locally over 4 inches of rain fell. D0 was pulled out of a small area where the heaviest rains fell, but otherwise the Drought Monitor depiction was not changed. Drier than normal conditions have prevailed since the start of the water year (October 1, 2014). Less than 2/3 of normal has fallen on much of the region since then, with a few areas below 50%. For the calendar year, totals are 7 to locally over 10 inches below normal
Looking Ahead
For the upcoming 5-day period (June 17-21), generally dry and significantly warmer than normal conditions are expected in the central Plains and from the Rockies westward to near the coast. roughly the western half of the country. Only isolated light rain at best is anticipated in areas south and west of Montana and the central sections of Wyoming, Colorado, and New Mexico. Forecast totals in eastern and northern parts of the Rockies are less than 0.5 inch. At the same time, daily high temperatures are expected to average 9 to 12 degrees F above normal in the Great Basin and central Rockies. The dryness and heat may quickly dry out the recent surface growth in that region, bringing ideal conditions for wildfires to develop and rapidly spread.In contrast, remnants of Tropical Storm Bill should bring a swath of heavy rain across east sections of Texas and Oklahoma, southern Missouri, the Ohio Valley, the central Appalachians, and (to a lesser extent) part of the lower Northeast. At least a couple inches of rain is expected, with peak amounts approaching 7 inches in southern Oklahoma, and 4.5 to 5.5 inches in southern sections of both Illinois and Ohio.
In the broad area north of this swatch, moderate rains of several tenths to almost not quite 2 inches are expected. Drier conditions are forecast to prevail south and east of the band of heaviest rainfall, with only a few tenths of an inch anticipated in Florida, the central Gulf Coast States, and southwestern South Carolina.
For the ensuing 5-day period (June 22-26), continued above normal temperatures are favored in most of the West, the Rockies, and the Southeast. The odds favor anomalous warmth in the mid-Atlantic, central Appalachians, middle and lower Mississippi Valley, and south-central Plains as well. Enhanced chances for cooler than normal weather are limited to a swath from the northeasternmost Plains eastward through the northern Great Lakes and much of the Northeast. In Alaska, the odds favor above normal temperatures everywhere except the northern fringe of the state, with odds for warmth progressively increasing southward.
Enhanced chances for heavier than normal rain cover the Great Lakes and Northeast, and a small area around the southern reaches of the Arizona/New Mexico border. However, dryness is favored to prevail from the south-central Plains eastward through the lower Mississippi Valley and the Southeast. The northwestern quarter of the contiguous states also has increased odds of abnormally light precipitation, as does all of Alaska outside the Aleutians and adjacent southwestern areas.
Author(s):
Richard Tinker, NOAA/NWS/NCEP/CPC
Dryness Categories
D0 ... Abnormally Dry ... used for areas showing dryness but not yet in drought, or for areas recovering from drought.Drought Intensity Categories
D1 ... Moderate DroughtD2 ... Severe Drought
D3 ... Extreme Drought
D4 ... Exceptional Drought
Drought or Dryness Types
S ... Short-Term, typically <6 months (e.g. agricultural, grasslands)L ... Long-Term, typically >6 months (e.g. hydrology, ecology)
