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Preliminary Report
unnamed tropical storm
(formerly Tropical Depression One-E)
13-16 May 1996

Edward N. Rappaport
National Hurricane Center
7 November 1996

Unnamed Tropical Storm
Tropical Depression 2-E
Hurricane Alma
Hurricane Boris
Tropical Storm Cristina
Tropical Depression 6-E
Hurricane Douglas
Tropical Storm Elida
Hurricane Fausto
Tropical Storm Genevieve
Hurricane Hernan
Tropical Depression 12-E

[1996 East Pacific Hurricane Season]

a. Synoptic History

The tropical storm formed about 800 miles to the south of the southern tip of Baja California, likely from a tropical wave analyzed to have crossed Central America and northern South America on 8 May. The associated thunderstorm activity was limited and sporadic until early on the 13th when it expanded and became more persistent. A band of deep convection developed on the northwest side of the system that morning. Dvorak T-numbers from the NESDIS Synoptic Analysis Branch (SAB) and the TPC Tropical Analysis and Forecast Branch (TAFB) reached 1.5 at 0600 UTC and then 2.0 at 1130 UTC that day. Based on those analyses, it is estimated that the system became a tropical depression at 0600 UTC on the 13th (Fig. 1 [19K GIF] and Table 1).

The cyclone moved toward the west-northwest at about 10 knots during its three-day existence and did not affect land.

There is uncertainty about the maximum intensity reached by this tropical cyclone. Operational estimates of 30 knots were based on application of the Dvorak technique. Those analyses of satellite pictures showed little variation, ranging from 30 knots by the Air Force Global Weather Central (AFGWC) and the TAFB, to 35 knots by the SAB. These maxima were generally centered on the early hours of 14 May, when a small core of deep convection developed in an environment with a southerly component of vertical wind shear. Subsequently, the U.S. Coast Guard relayed reports to the National Hurricane Center from the vessel Solar Wind suggesting that the cyclone had maximum winds of tropical storm strength on the 14th.

Deep convection near the circulation center became spotty by late on the 14th and then disappeared completely on the night of the 15th-16th. The system dissipated on the 16th.

b. Meteorological Statistics

Figures 2 (22K GIF) and 3 (23K GIF) show the tropical storm's estimated central pressure and maximum one-minute wind speed, respectively, versus time and the associated satellite and ship intensity data. Position and intensity estimates from satellite pictures were provided by the AFGWC, TAFB and SAB.

The Coast Guard reported that at least two vessels, including the 37-ft trimaran Solar Wind and the True Blue were affected by the cyclone. Analysis of satellite pictures early on the 14th suggests that the Solar Wind was located in the general vicinity of an isolated thunderstorm cluster seen just north of the circulation center. The Solar Wind observed a wind speed of 35-42 knots for an unspecified period near 0400 UTC on the 14th and the anemometer showed its maximum capability, 60 knots, for an unknown duration near 0600 UTC. The 0400 UTC report from that ship also included an observation of 4-6 ft seas, which would be generally consistent with either localized, transitory winds of the magnitude reported or lower wind speeds than noted. The True Blue was located about 50 miles to the north of the Solar Wind during this period and reported winds of 20 knots. The maximum one-minute wind speed for this storm is now estimated to have been 45 knots at 0600 UTC on the 14th.

c. Casualty and Damage Statistics

Communications with the Solar Wind were lost after 0600 UTC on the 14th. The Coast Guard began, but later suspended, a search for the vessel and its two-man crew. The fate of the crew remains unknown.

d. Forecast and Warning Critique

The tropical cyclone was of tropical storm strength for too short a period to obtain a meaningful quantitative evaluation of forecast track accuracy.

The observations and analyses of this tropical cyclone serve as reminders of the large uncertainty often associated with tropical cyclone intensity estimates. They also call attention to the great importance and scarcity of reliable surface weather observations in the vicinity of tropical cyclones. Such limitations diminish the accuracy and reliability of warnings.

Table 1. Preliminary best track, unnamed tropical storm, 13-16 May 1996.
Position Pressure
Wind Speed
Lat. (°N)Lon. (°W)
13/060011.1113.9100925 Tropical Depression
120011.3115.2100830" "
180011.6116.3100630" "
14/000011.8117.5100340 Tropical Storm
060012.1118.8100045" "
120012.4119.9100240" "
180012.8121.0100535" "
15/000013.0121.8100630 Tropical Depression
060013.2122.6100730" "
120013.4123.4100730" "
180013.6124.2100830" "
16/000013.8124.9100830" "
060014.0125.7100825" "
120014.1126.3100925" "
180014.2126.7100925" "
17/0000     Dissipated
14/060012.1118.8100045 Minimum Pressure

Brian Maher
Jack Beven

Last updated December 29, 1998