Michigan drought update for July 25, 2012

The next week or two is forecasted to bring at least a temporary break to the drought conditions.

Showers and thunderstorms moving around the northern periphery of the vast upper air ridge across the central United States brought much-needed rainfall to many sections of Michigan during the past several days, including the southwestern Lower Peninsula, which had been repeatedly missed by earlier precipitation. While the rainfall provided at least some temporary relief from moisture stress, more will be needed in the coming weeks given near peak crop-water use demands and extremely low soil moisture reserves.

As of July 17, the percentage of the state experiencing drought conditions or abnormal dryness as defined by the U.S. Drought Monitor had grown to 82 percent. There was also an expansion of the area of severe or worse drought conditions to 21 percent and the first appearance of “extreme” drought conditions in a narrow area of southern Lower Michigan along the Indiana border.

Latest forecast guidance suggests some changes in the next one to two weeks that should result in at least a temporary break in the drought conditions. During the next 48 to 72 hours (as of July 25, 2012), two weather systems are expected to bring significant rainfall to the state with widespread heavy rain possible in northern sections late Wednesday through Thursday morning (July 25-26). Additional scattered showers and thunderstorms are possible Thursday and during the day Friday (July 27). Fair, somewhat cooler and less humid weather is likely this weekend. After one more relatively hot day Thursday with highs in the 80s to mid-90s, daytime temperatures will generally fall back to a range from the mid- and upper 70s far north to the mid- to upper 80s south. Lows will be in the 60s.

In the medium range time frame, forecast guidance suggests that the axis of the upper air ridge across the central United States will shift westward and flatten somewhat, which should leave Michigan and the Great Lakes region under northwesterly flow aloft. This pattern would lead to somewhat cooler temperatures and more frequent chances for rain.

The latest NOAA Climate Prediction Center 6-10 day and 8-14 day outlooks (for July 30 to August 3 and August 1-7) both call for near to above normal mean temperatures and precipitation totals. New 30-day and three-month outlooks for the month of August and August through October period both call for warmer than normal temperatures to continue state and region wide for both periods, and for below normal precipitation totals across southern sections of the state. Precipitation totals across northern sections are forecast to remain in the “climatology” category, suggesting near equal odds of below, near and above normal totals. These outlooks are based primarily on continuity, with the widespread impacts of this year’s drought (i.e., large areas of abnormally dry soils) likely to continue to influence weather patterns in the region through the late summer.

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