Tropical Depression One-E originated from a tropical wave that exited the coast of Africa on May 29.
Little convective activity was associated with the system as it traveled across the Atlantic Ocean and Caribbean Sea.
On June 10, the wave crossed Central America and entered the northeastern Pacific basin.
Over the following few days, the system gradually became better organized and on June 15, an area of low pressure developed from the wave.
The system continued to organize, and on June 17 the National Hurricane Center (NHC) noted the likelihood for tropical cyclogenesis; although, at the time, the circulation was not well-defined.
It organized further, and on June 18, the NHC initiated advisories on the first tropical depression of the 2009 season about 350 miles (565 km) south-southwest of Mazatlán, Sinaloa.
Deep convection persisted near the southern portion of the depression; however, the northern portion of the depression was partially devoid of convective activity.
The depression traveled northward along the periphery of a mid-level ridge over Mexico and an unusually strong mid to upper-level trough situated over the Baja California Peninsula.

Later on June 18, forecast models indicated that the system might rapidly degenerate prior to landfall.
However, the NHC continued to forecast that the depression would attain tropical storm-status before landfall.
Shortly after, the depression became increasingly disorganized as convection separated from the center of circulation due to increasing wind shear.
Stable air ahead of the system inhibited the possibility of rapid development as warm waters supported intensification.
By the morning of June 19, the center of circulation was situated along the southern edge of deep convection, indicating that the depression was beginning to degenerate.
Despite this, the NHC continued to anticipate intensification prior to landfall.
Embedded within an easterly flow ahead of a mid-level trough, the storm turned towards the north-northeast and accelerated slightly.
At 11:00 am PDT (1800 UTC), the depression reached its peak intensity with winds of 35 mph (55 km/h) and a barometric pressure of 1003 mbar (hPa; 29.62 inHg).
Operationally, the depression was considered to be slightly stronger, having a minimum pressure of 1001 mbar (hPa; 29.56 inHg).
Later that day, the depression began to degenerate into an open trough as it was situated underneath cirrus clouds instead of cumulonimbus clouds.
Visible satellite imagery showed that the depression became increasingly ill-defined and the NHC estimated that the depression degenerated into a trough of low pressure near the Islas Marías during the afternoon of June 19.
The remnants of the depression were monitored by the United States Naval Research Laboratory for several more hours until the system moved inland over Sinaloa.
Tropical Depression One-E originated from a tropical wave that exited the coast of Africa on May 29. Little convective activity was associated with the system as it traveled across the Atlantic Ocean and Caribbean Sea. On June 10, the wave crossed Central America and entered the northeastern Pacific basin. Over the following few days, the system gradually became better organized and on June 15, an area of low pressure developed from the wave. The system continued to organize, and on June 17 the National Hurricane Center (NHC) noted the likelihood for tropical cyclogenesis; although, at the time, the circulation was not well-defined. It organized further, and on June 18, the NHC initiated advisories on the first tropical depression of the 2009 season about 350 miles (565 km) south-southwest of Mazatlán, Sinaloa. Deep convection persisted near the southern portion of the depression; however, the northern portion of the depression was partially devoid of convective activity. The depression traveled northward along the periphery of a mid-level ridge over Mexico and an unusually strong mid to upper-level trough situated over the Baja California Peninsula.
Later on June 18, forecast models indicated that the system might rapidly degenerate prior to landfall. However, the NHC continued to forecast that the depression would attain tropical storm-status before landfall. Shortly after, the depression became increasingly disorganized as convection separated from the center of circulation due to increasing wind shear. Stable air ahead of the system inhibited the possibility of rapid development as warm waters supported intensification. By the morning of June 19, the center of circulation was situated along the southern edge of deep convection, indicating that the depression was beginning to degenerate. Despite this, the NHC continued to anticipate intensification prior to landfall. Embedded within an easterly flow ahead of a mid-level trough, the storm turned towards the north-northeast and accelerated slightly. At 11:00 am PDT (1800 UTC), the depression reached its peak intensity with winds of 35 mph (55 km/h) and a barometric pressure of 1003 mbar (hPa; 29.62 inHg). Operationally, the depression was considered to be slightly stronger, having a minimum pressure of 1001 mbar (hPa; 29.56 inHg). Later that day, the depression began to degenerate into an open trough as it was situated underneath cirrus clouds instead of cumulonimbus clouds. Visible satellite imagery showed that the depression became increasingly ill-defined and the NHC estimated that the depression degenerated into a trough of low pressure near the Islas Marías during the afternoon of June 19. The remnants of the depression were monitored by the United States Naval Research Laboratory for several more hours until the system moved inland over Sinaloa.
Tropical Depression One-E (2009)