Sunday, September 29, 2013

Tropical Storm Jerry (2013)

Storm Active: September 28-October 3

On September 26, a large area of disturbed weather formed over the central Atlantic ocean in association with a surface trough and an upper-level low. The system moved generally northwestward over the next couple of days, and despite fairly strong upper-level winds, thunderstorm activity began to concentrate around a forming low pressure center on September 27. During the next day, convection remained displaced to the north or northeast of the center of circulation, even though gale force wind gusts appeared to be occurring, and so the system was not yet tropical, but a slight increase in organization late on September 28 indicated the formation of Tropical Depression Eleven.

At the time of formation, the depression was skirting around the northern periphery of a subtropical ridge, and it turned northeast by early on September 29. The center continued to be alternately exposed and covered by a temporary canopy of convection throughout that day due to continuing shear, so the system's depression status was maintained. Overnight, a stronger burst of thunderstorm activity appeared, though it still remained largely in the eastern half of the circulation. However, slow development continued, and by by late morning on September 30, the system was upgraded to Tropical Storm Jerry.

The banding features of the circulation also improved that night, and the maximum winds of Jerry increased. However, the increase in organization was short-lived, as the convective structure deteriorated significantly early on October 1, and the storm weakened again. An upper-level low above the system continually bashed it with dry air, contributing to the weakening. By this time, the development of another ridge to Jerry's north left the cyclone in very weak steering currents, and so the storm was nearly stationary. Over the next day, the storm changed very little, and moved very little; even by the morning of October 2 it had only begun to drift back westward.

Finally, a trough moving moving northeastward picked up Jerry later that day, and began to accelerate the system northeastward. By this time, Jerry displayed deep convection so intermittently that it had to be downgraded to a tropical depression that night. On October 3, the system fell below the organization threshold of a tropical cyclone, and was downgraded to a remnant low. Over the next several days, the remnants continued northeastward and interacted with a trough of low pressure, the combination eventually bringing some rainfall to the Azores Islands.

Jerry experienced strong wind shear throughout its lifetime.

Tropical Storm Jerry remained nearly stationary for about a day around October 2 when it was embedded in weak steering currents.

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