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Climate Prediction Center


July - September 2003


Latest Seasonal Assessment - Large moisture deficits accumulated in recent years have resulted in severe to exceptional drought conditions (D2-D4) across Utah, Nevada, Arizona, northern New Mexico, southwestern Wyoming, southern and western Colorado. Long term drought conditions are expected to persist throughout the period in this region. Further north, significant improvement has been observed across northern Colorado, eastern Montana, northern and eastern Wyoming. Some improvement is expected across southeastern Montana and northern Wyoming. However, long term impacts are expected to persist. Improvement is expected to continue across Nebraska, extreme eastern Wyoming and western South Dakota. Further south, improvement is expected across eastern New Mexico, Texas and Louisiana. However, periodic dry spells are possible.

Discussion for the Seasonal Drought Outlook

Tools used in the drought outlook included: the official CPC long-lead precipitation outlook for July-September, the Palmer Drought Index probability projections for September and various medium and short-range forecasts and models such as the 6-10 day and 8-14 day forecasts. The latest western water supply forecast is also considered.

Wet conditions across Idaho, Montana, Wyoming and northern Colorado have helped to reduce long term moisture deficits and ease drought impacts. Some further improvement is expected across southeastern Montana, eastern and northern parts of Wyoming. However, large deficits accumulated in recent years continue to result long term drought conditions (D2-D4) across southwestern Wyoming, Utah, Nevada, southern and western Colorado and northern portions of New Mexico and Arizona. With typically dry conditions expected during the summer across southwestern Wyoming, northern Nevada and northern Utah , long term drought conditions will persist. Across most of Arizona, rainfall typically increases during late July as the monsoon sets in. This will result in some improvement in the drought situation. However, due to the long term nature of the drought, the improvement will be quite limited as even a very wet monsoon will not break the current drought across much of the state. Across eastern New Mexico and western Texas, the majority of annual precipitation falls during the summer. With normal to above normal rainfall expected, improvement is expected in this area.

Across eastern Texas and western Louisiana, a dry April and May resulted in 90 day rainfall departures of 100 to 200 mm by June 1 (25 to 50% of normal). However, recent rains have served to reduce these deficits. The overall trend is for improvement across this area, although periodic dry spells are certainly possible. The "wild card" in this outlook, especially during the last half of the period, is tropical storms. One tropical system could eliminate any rainfall deficit very quickly. Further north, an active spring weather pattern has resulted in improvement across western Nebraska and portions of South Dakota. These areas are expected to continue to improve throughout the period. However, as with the western Gulf Coast, periodic dry spells are possible.

Across northern Minnesota, winter and early spring were very dry. However, the majority of the regions' annual precipitation falls during the warm season. As a result, impacts from the recent dry winter will likely ease with minimal moisture deficits expected. Long term dryness has resulted in a three year precipitation deficit of 18 to 24 inches across much of Maine. Summer rains will result in some improvement. However, only a exceptionally wet summer would result in a major reduction in these deficits, which is not anticipated.

NOAA/ National Weather Service
NOAA Center for Weather and Climate Prediction
Climate Prediction Center
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Page Author: Climate Prediction Center Internet Team
Page last modified: June 19, 2003
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