National Weather Service United States Department of Commerce

Flooding Threat Along the Gulf Coast, Southern Rockies and High Plains; Cooler Weather in the Central and Eastern U.S.

Strong thunderstorms may bring excessive rainfall and flooding over parts of the northern Gulf Coast today and over parts of the southern Rockies into the High Plains today through the weekend. A refreshingly cool and dry air mass will continue to produce below average temperatures across the central and eastern U.S. through the weekend. Read More >

Monthly Precipitation Anomalies


Figure 3


a)


Monthly Precipitation Anomalies El Nino

b)


Monthly Precipitation Anomalies La Nina


Fig. 3. Total precipitation deviation from the monthly historical average during (a) El Niño and (b) La Niña events. Composites are made from all the historical El Niño or La Niña events.



Figure 4


a)


Monthly Precipitation Anomalies El Nino

b)


Monthly Precipitation Anomalies La Nina


Fig. 4. Total precipitation deviation from the monthly historical average during (a) El Niño and (b) La Niña events. Composites are made from all the historical El Niño or La Niña events.

Both Fig. 3 and Fig.4 show the deviation from the monthly total precipitation relative to historical average given in Fig. 2. and Table 1. However, the information in Fig. 3 is in unit of inches, while that in Fig. 4 is presented by percentage.
 
The monthly total precipitations at all six stations are slightly more than historical average during the El Niño year. However, from January to June of the year after an El Niño event, there is deficient precipitation. The maximum difference could reach as much as 3 inches (around 80%) less than its historical average amount at one station. During a La Niña event, on the other hand, moderate deficient precipitation took place in the first half of the La Niña year. While from October to the end of the next year there is more precipitation. Usually, there is 1-2 inches, or 20-40%, more than the historical average.
 

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