Flood Watch

* WHAT...Flooding caused by excessive rainfall is possible.

* WHERE...Much of south-central New Mexico and Far West Texas, including El Paso, Las Cruces, and the Mesilla Valley.

* WHEN...From Tuesday afternoon through Wednesday evening.

* IMPACTS...Excessive runoff may result in flooding of arroyos, rivers, streams, and other low-lying and flood-prone locations. Flooding may occur in poor drainage and urban areas. Low-water crossings may be flooded, resulting in road closures.

* ADDITIONAL DETAILS... - An early season back door cold front will interact with a late season plume of deep monsoonal moisture, bringing several rounds of thunderstorms with torrential downpours to the region Tuesday afternoon through Wednesday evening. Repeated thunderstorms may tend to focus in one or two areas, resulting in higher end precipitation totals. The most critical period with the heaviest rain potential will likely be Tuesday night into Wednesday morning. - A broad swath of moderate to locally heavy rainfall is likely to affect most of the Watch area between late Tuesday afternoon and Wednesday evening, with typical, scattered monsoon season flood impacts. However, there is increasing potential for a narrow band of repeated thunderstorms which will result in particularly heavy rainfall amounts, possibly exceeding 3 inches in a 6 to 12 hour period, resulting in higher-end impacts. Forecast models currently favor placing the focus for heaviest rainfall over the Mesilla Valley and El Paso. But forecasts this far out, especially when dealing with thunderstorms, are simply not accurate enough to precisely tell yet where exactly this area of heaviest rainfall will set up. It could just as easily shift west or east and avoid the more populated corridor. - http://www.weather.gov/ElPaso