John was a tropical storm for several days and moved from the eastern to the central Pacific basin. John did not affect land.
a. Synoptic history
John originated as a disturbance in the intertropical convergence zone (ITCZ). By 25 August, an area of cloudiness in the ITCZ became concentrated about 1200 n mi southwest of the southern tip of Baja California. A low-level cloud circulation became apparent from visible satellite imagery late on the 26th. The twelfth tropical depression of the season in the eastern Pacific basin formed early on the 28th about 1700 n mi west-southwest of Baja California, when convection became well organized. The best track begins at this time and best track positions are plotted in Figure 1. Figure 2 and Figure 3 show plots of best-track wind speed and pressure curves as a function of time, along with the data on which they are based. Table 1 lists best track position, maximum one-minute surface wind speed, and minimum central surface pressure at six-hour intervals.
John strengthened from a depression to an estimated 55-knot tropical storm in about 18 hours on the 28th, as a small central dense overcast feature developed. John's motion was slow and northwestward under the steering of a weak mid-level ridge to its north on the 28th and 29th and the intensity remained the same during this time. Early on the 30th, still moving slowly, John moved across 140W longitude into the central Pacific basin. John reached its peak intensity of 60 knots on the 30th while its motion became very slow and erratic. It began moving slowly westward on the 31st and gradually lost convection and weakened under strong vertical shear and dissipated on 1 September about 750 n mi east-southeast of the Hawaiian Islands.
b. Meteorological statistics
Satellites were the single source of data for determining the best track given in Table 1 in the eastern Pacific basin. Best-track data west of 140W longitude was provided by the Central Pacific Hurricane Center in Honolulu, Hawaii.
c. Casualty and damage statistics
There were no reports of death or damage.
d. Forecast and warning critique
There were six forecasts made in the eastern Pacific basin that verified while John was a tropical storm and there were only two 72-hour forecasts verified. The track errors were rather small ranging up to 103 n mi at 72 hours. There was a negative intensity bias during the formative stage and a slight positive bias thereafter.
Figure 1. Best track positions for Tropical Storm John, 28 August - 1 September 2000.
Figure 2. Best track one-min. wind speed curve, 28 August - 1 September 2000.
Figure 3. Best track minimum central pressure curve for Tropical Storm John, 28 August - 1 September 2000.
Table 1. Best track data for Tropical Storm John, 28 August - 1 September 2000. Data west of 140W longitude provided by Central Pacific Hurricane Center. Date/Time
(UTC)Position Pressure
(mb)Wind Speed
(kt)Stage Lat. (°N) Lon. (°W) 28/0600 14.9 137.4 1007 30 tropical depression 1200 15.1 137.8 1005 35 tropical storm 1800 15.4 138.2 1003 45 " 29/0000 15.7 138.5 1001 55 " 0600 16.1 138.9 1000 55 " 1200 16.6 139.2 999 55 " 1800 16.8 139.7 998 55 " 30/0000 16.9 140.1 997 55 " 0600 17.1 140.4 996 55 " 1200 17.2 140.5 996 55 " 1800 17.3 140.4 994 60 " 31/0000 17.4 140.3 996 55 " 0600 17.2 140.6 999 45 " 1200 17.0 141.2 1004 35 " 1800 17.1 141.7 1006 35 " 01/0000 17.3 141.9 1006 30 tropical depression 0600 17.4 141.9 1008 30 " 1200 17.5 141.9 1008 25 " 30/1800 17.3 140.4 994 60 minimum pressure
