Characteristic patterns associated with atmospheric circulation changes over the Northeastern Tropical Pacific in summer

The summer patterns of precipitation, sea level pressure, outgoing long-wave radiation, and vertical velocity associated with changes in the near surface zonal winds over the central northeastern tropical Pacific (NTP) (10ºN-15ºN, 115ºW-95ºW), are analyzed in the intraseasonal and synoptic time scales. It is shown that easterlies over this region are associated with a high pressure system over the Gulf of Mexico and the southeastern United States, which induces subsidence and inhibits convection over the western Gulf of Mexico and adjacent continental regions. Also, the strengthening of the western Caribbean trades and of the Tehuantepec and Papagayo wind jets is induced. Easterlies over the central NTP are also associated with reduced moisture transports from the Pacific ocean to the adjacent southern Mexico and Central American coasts and with the westward shift of deep convection and precipitation. This overall pattern is related with the midsummer drought observed in some regions of the eastern NTP, southern Mexico and Central America.