[NCEP Logo]

Preliminary Report
Hurricane Jimena
25-30 August 1997

Lixion A. Avila
National Hurricane Center
16 September 1997

Tropical Storm Andres
Tropical Storm Blanca
Tropical Depression 3-E
Tropical Storm Carlos
Tropical Depression 5-E
Hurricane Dolores
Hurricane Enrique
Hurricane Felicia
Hurricane Guillermo
Tropical Storm Hilda
Tropical Storm Ignacio
Hurricane Jimena
Tropical Storm Kevin
Hurricane Linda
Tropical Storm Marty
Hurricane Nora
Tropical Storm Olaf
Hurricane Pauline
Hurricane Rick

[1997 EPAC Hurricane Season]

Hurricane Jimena was characterized not only by its exceptionally rapid intensification but also by its sudden and accelerated decay.

a. Synoptic History

Jimena developed from a large area of disturbed weather centered in the vicinity of 10°N 130°W, where the sea surface temperatures were 1.0 or 1.5 degrees above normal. This system was probably related to a tropical wave which moved slowly westward for several days across the eastern North Pacific. Initially, the disturbance was under an unfavorable upper-level westerly wind environment. The convection increased and an upper-level anticyclone gradually built over the system. A tropical depression formed near 10.9°N 133.1°W at 1200 UTC 25 August. After becoming a tropical storm by 0000 UTC 26 August, Jimena intensified rapidly. It quickly developed an eye and the Dvorak T-numbers increased substantially. In fact, the estimated winds increased from 65 knots to 115 knots in about 12 to 15 hours. Jimena's winds were 115 knots for a couple of days and peaked at 120 knots at 1500 UTC 28 August. The objective T-numbers near that time were oscillating around 6.5 on the Dvorak scale. Jimena was moving on a north- northwesterly track when a strong upper-level trough moved by and sheared the hurricane. Jimena weakened as fast as it developed. Wind estimates decreased from 115 to 30 knots in about 24 hours.

The remaining low-level circulation center moved westward across 140°W and entered the Central Pacific Hurricane Center (CPHC) area of responsibility just after 1200 UTC on the 29th. It weakened further and was declared dissipated by 0000 UTC 30 August.

Jimena's track is shown in Fig. 1 (9K GIF). Table 1 is a listing, at six-hourly intervals, of the best-track position, estimated minimum central pressure and maximum 1-minute surface wind speed.

b. Meteorological Statistics

The best track pressure and wind curves as a function of time are shown in Figs. 2 (8K GIF) and 3 (8K GIF) and are based on satellite intensity estimates from the Tropical Analysis and Forecast Branch (TAFB), the Satellite Analysis Branch (SAB) and the Air Force Global Weather Center (AFGWC). The estimated central pressure of Jimena dropped at a rate of 3.5 mb an hour during its rapid intensification phase from 0000 to 1200 UTC 27 August.

c. Casualty and Damage Statistics

There are no reports of casualties or damage associated with Jimena.

d. Forecast and Warning Critique

The average official forecast error (11 forecasts) at 24 hours was 101 n mi and reached 456 n mi at 72 hours (3 forecasts). These numbers are much larger than the long-term (1988-1995) average errors of 71 and 196 n mi, respectively.

None of the official forecasts captured either the rapid intensification nor the rapid decay.

Table 1. Best track, Hurricane Jimena, 25- 30 August, 1997.
Position Pressure
Wind Speed
Lat. (°N)Lon. (°W)
25/120010.9133.1100925 tropical depression
26/000011.3134.3100535 tropical storm
060011.5 134.8100140"
1800 14.4 136.1948115"
28/000015.1 136.3948115"
060020.2138.898060 tropical storm
1800*20.6140.5100830 tropical depression
30/000020.5141.2100925 dissipating
28/150018.0137.5942120 minimum pressure

* Best track west of 140°W was provided by CPHC

Brian Maher
Jack Beven

Last updated December 26, 1998