California and National Drought Summary for June 30, 2015

Summary

A strong ridge over the west and a deep trough over the east dominated the weather this past week. Record high temperatures were recorded over much of the west, with many locations reaching temperatures in the 110 degree range during the week. The heat along with very dry conditions over the last 30 days has elevated the fire risk over much of the west. From the Midwest into New England, several storms tracked through the region, bringing rain to much of the area. Some areas of the Midwest recorded more than 5 inches of rain in the last week. Along with the rain, cooler than normal temperatures prevailed. Spotty convective precipitation was common in the southeast, where temperatures were above normal this week. Rain in Texas helped to keep this area cooler than normal for the week. Much of the central plains was dry and warmer than normal into the Dakotas.

Great Plains

This was a fairly dry week over the region, with just spotty precipitation along the foothills in Colorado, the Panhandle of Nebraska, and into southwestern South Dakota as well as west Texas. Except for the areas that received the most rain, temperatures were above normal in most places with departures of 2-4 degrees above normal. There were not any changes in the regional drought depiction this week.

Hawaii, Alaska and Puerto Rico

Continued dryness in Puerto Rico has led to further degradations with an expansion of D1 and D2 conditions this week. In Alaska, the continuing dryness over portions of the state has led to an expansion of D1 this week. There were no changes for Hawaii.

Midwest

A wet and cool week over the region brought heavy rain from Iowa to Ohio. The last several weeks have been wet enough to allow improvements over Kentucky, Indiana, Ohio, and Minnesota. For Kentucky, a full category improvement was made in the northern, central, and eastern portions of the state. D0 was removed from Indiana and Ohio while the D0 in northern Minnesota was reduced in size. The wet and cool weather has caused numerous planting delays, especially for soybeans.

Southeast

Temperatures were warmer than normal over much of the region, with the Carolinas and Florida having the greatest departures of 2-4 degrees above normal for the week. Spotty rainfall over the region combined with the warm temperatures has allowed for the expansion of drought in northern Alabama, where D1 was expanded over the northern portions of the state and into northwest Georgia. In southern Georgia, D0 and D1 was expanded this week and D1 migrated out of South Carolina and into southeast Georgia as well. Some improvements were made to the D0 in North Carolina as the eastern extent has received enough precipitation over the last several weeks to warrant improvement. The two separate areas of D1 in the Carolinas were joined as the area in north central South Carolina generally has been drying out over the last 30-60 days. South Florida remains dry and D1 was pushed farther up the Atlantic coast this week while D0 was expanded slightly to the west.

The Northeast/ Mid-Atlantic

Most areas were 4-6 degrees below normal for the week and almost all areas received some precipitation as well. The greatest amounts of rain were recorded over Pennsylvania and into portions of the Mid-Atlantic, where up to 5 inches of rain was common from eastern Virginia into southern Maryland. After a dry spring, the last month has brought with it above-normal precipitation. With the wetter trend and positive responses being observed to the local hydrological systems, improvements were made this week in the region. D0 conditions improved in Maine while a full category improvement was made in New Hampshire and Vermont. D0 was removed from Pennsylvania and New Jersey while D0 and D1 were improved in both New York and Massachusetts.

West

Record heat and dryness over the region this week as well as over the last month has quickly deteriorated conditions in many areas after a wet May. A large degradation of drought in Montana was made this week with a full category change in the areas of western and north central Montana. In Washington, D2 was pushed to the west and D1 was added in the central portion of the state while in Oregon, D2 was expanded in the southwest and in the northeast into Idaho.

Looking Ahead

Over the next 5-7 days, a significant system will continue to push through the Tennessee River Valley, with the heaviest rains projected to be centered over southern Missouri, northern Arkansas, and Tennessee, where amounts could surpass 5 inches. In general, it looks to be a fairly active summer pattern over the United States, with many areas having the opportunity for rain. The central plains (up to 1.40 inches), southern Rocky Mountains (up to 2.0 inches), and south Texas (up to 1.60 inches) look to be the areas of the greatest precipitation potential. With the rain potential, temperatures over most of the country are expected to be 3-5 degrees below normal. The Pacific Northwest is the anomaly as dry conditions are expected to continue and daytime high temperatures are expected to be 12-15 degrees above normal.

The 6-10 day outlooks show that the best chances for below-normal temperatures are over the high plains and Midwest. The greatest chances of above-normal temperatures will continue to be in the Pacific Northwest and Alaska as well as over much of the Gulf Coast and Florida. The greatest probability of above-normal precipitation will be from the Great Basin into the central plains and up into the northeast. Below-normal precipitation chances are greatest over the Gulf Coast and Florida, the northern high plains, and the Pacific Northwest.

Author(s):
Brian Fuchs, National Drought Mitigation Center

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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 Drought

D2 ... 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)
Source: The National Drought Mitigation Center