MARCH-MAY 2013 90-DAY OUTLOOK
332 PM EDT Fri. Mar. 1, 2013

Atmospheric patterns, 700 MB and 500 MB height anomalies, statistical data, and various models such as the ECMWF monthly, NMME, IMME and the CFSv2, along with observed cases from past such months, data from 1895-2000 were used in this forecast.

Sea surface temperatures across the equatorial Pacific remain slightly below normal, and
have further cooled in February. The MJO has been active and it is forecast to continue. Global sea surface temperature anomaly patterns reflect a negative phase of the
PDO. This also includes a large region of warm anomalies in the central north Pacific Ocean with negative sea surface anomalies in the extra-tropics to its west, north and east and southeast, including a weak negative anomalies in the eastern equatorial Pacific.

The MJO remained active over the past week with the enhanced convective phase crossing the Indian Ocean and enhanced convection is becoming better organized on a large scale over the Maritime continent. A strong atmospheric Kelvin wave crossed the Indian Ocean and the Maritime continent in recent days and has contributed to the increase in convection in this area and has effectively resulted in quick propagation of the MJO to the western Maritime continent. Enhanced convection was observed during the past week across the western Pacific and Indian Ocean, primarily north of the equator. Suppressed convection was strong over portions of the southwest Pacific and parts of Brazil. Suppressed phases of the Kelvin Wave and an equatorial Rossby wave generally resulted in mixed convection over the Indian Ocean.

Dynamical model forecast some gradual eastward propagation of the MJO during the upcoming week with the enhanced convective phase centering across the Maritime continent. The models, however, also show a considerable reduction in amplitude throughout the period and stop eastward propagation by Week-2. Influence from other types of sub-seasonal tropical variability are likely contributing to the behavior seen in the forecasts like the Kelvin Wave and westward moving Rossby wave and it is too soon to say that the MJO is weakening over the longer term. The official forecast favors a continuation of a slowly evolving MJO signal over the Maritime continent during the period.

Above normal temperatures are forecast for the central and southern Rockies, the central and southern Plains, the lower Mississippi and Tennessee Valleys. The probability of above normal temperatures across this region is 57%.. The remainder of the nation is not expected to exceed climatological values. All spatial anomalies forecast above normal temperatures for most of the nation.

Below normal precipitation is forecast for the West coast, the lower and upper Great Basin and Texas. The probability of below normal precipitation for this area is 56 percent. The remainder of the nation is not expected to exceed climatological values. The CFSv2 depicts above normal precipitation in the East. The other spatial anomalies forecast below normal precipitation for most of the nation.