Thursday, June 23, 2011

The latest US Drought Monitor

US Drought Monitor: ENSO-neutral conditions developed during the first part of June, but in the wake of the 2010-2011 La Nina, widespread drought developed and persisted across the southern tier of the U.S. Significantly, nearly 60 percent of the current drought areas are extreme or exceptional, with many areas experiencing record precipitation deficits. During the previous two weeks, exceptional drought continued to expand across the southern Rockies, south-central Plains, and portions of the Southeast.

The summer onset of the rainy season in Florida has been delayed, exacerbating the long standing drought and contributing to outbreaks of wildfires, while the North American Monsoon has also seen a sluggish start, where Arizona is currently battling the largest wildfire in state history. Due to the expected onset of the rainy season in Florida and monsoon thunderstorms across the Southwest, drought improvement is expected during the upcoming three months.

Enhanced chances of above-median rainfall across the southern Atlantic states also favors drought amelioration. In contrast, a dry climatology and above-median temperatures expected during the summer months across the southern Plains limits opportunities for drought reduction. Across the remainder of the Southeast, some improvement is possible under a summertime convective regime, although rainfall deficits are substantial and long-term in some areas, particularly across Louisiana. The prospect of tropical cyclones, with an expected above-normal season peaking in September, adds to the forecast uncertainty. Across Hawaii, leeward drought persistence is expected under the summer trade wind regime.

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