Kristy was a short-lived, uneventful tropical cyclone that moved little during its existence.
a. Synoptic History
Kristy's development appears to be at least partly attributable to a tropical wave which moved off the coast of Africa on 12 August. The northern portion of this wave spawned Tropical Storm Chris east of the Leeward Islands on 17 August. Radiosonde data from the Lesser Antilles and satellite pictures show that the southern part of the wave continued westward into the Caribbean on 19 August. The wave was ill-defined as it moved westward over northern South America for the next few days. It crossed over Central America on the 22nd, and continuity of westward motion puts the wave at about 124°W on 28 August, in the same locale as an area of disturbed weather. The next day, a low-cloud swirl was identifiable in the vicinity of 12°N 128°W. By the 30th, the system crossed 130°W where there was an increase of deep convection just west of the center. Based on the development of deep convection close to the low-cloud center, it is estimated that Tropical Depression Thirteen-E formed at 0000 UTC 31 August. The system was centered about 1380 n mi west-southwest of Cabo San Lucas at that time.
The cyclone moved slowly west-northwestward for about a day, but steering currents soon collapsed, with weak low-level ridging to the north of the system and a band of low-level westerlies to its south. A weak steering regime persisted through the short life of the tropical cyclone, resulting in little overall motion. Also, the meandering depression remained in an environment of moderate easterly vertical shear, and this prevented significant strengthening. Around 0000 UTC 2 September, however, microwave imagery showed that the system had become a little better organized, suggesting that the cyclone became Tropical Storm Kristy at that time. Deep convection near the center fluctuated for a while, but by 1800 UTC 2 September, the low-level center became separated from the main area of convection, which indicated that the system weakened back to a tropical depression. Soon the low-level center became distorted and the cyclone dissipated by 0600 UTC 3 September, in a place not far from where it originated.
b. Meteorological Statistics
Table 1 lists Kristy's best track positions and intensities at six-hourly intervals, and Fig. 1 shows its track. Figure 2 and Figure 3 depict the curves of maximum one-minute average "surface" (10 meters above ground level) wind speed and minimum central sea-level pressure for Kristy, respectively, as functions of time. Also plotted are the observations on which the curves are based. These consist of Dvorak-technique estimates using satellite imagery by the Tropical Analysis and Forecast Branch (TAFB), the Satellite Analysis Branch (SAB), and the U.S. Air Force Weather Agency (AFWA).
c. Casualty and Damage Statistics
No reports of casualties or damages associated with Kristy have been received.
d. Forecast and Warning Critique
Because Kristy was so short-lived, there are no meaningful forecast verification statistics. In most of the official forecasts, Kristy was moved several degrees too far to the west, and the intensity of the system was generally over-predicted.
Table 1. Best track, Tropical Storm Kristy, 31 August - 3 September 2000. Date/Time
Stage Lat. (°N) Lon. (°W) 31 / 0000 13.0 131.4 1008 25 tropical depression 31 / 0600 13.2 132.2 1008 25 " 31 / 1200 13.4 132.6 1008 30 " 31 / 1800 13.5 133.0 1007 30 " 01 / 0000 13.7 133.2 1007 30 " 01 / 0600 13.8 133.2 1007 30 " 01 / 1200 13.8 133.3 1006 30 " 01 / 1800 13.5 133.3 1006 30 " 02 / 0000 13.2 133.3 1004 35 tropical storm 02 / 0600 13.2 133.5 1005 35 " 02 / 1200 13.6 133.4 1006 35 " 02 / 1800 14.3 133.2 1007 30 tropical depression 03 / 0000 14.7 133.2 1007 25 " 03 / 0600 dissipated 02 / 0000 13.2 133.3 1004 35 minimum pressure
Figure 1. Best track positions for Tropical Storm Kristy, 31 August - 3 September 2000.
Figure 2. Best track maximum sustained surface wind speed curve for Tropical Storm Kristy, 31 August - 3 September 2000.
Figure 3. Best track minimum central pressure curve and central pressure estimates for Tropical Storm Kristy, 31 August - 3 September 2000.