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
(UTC) | Position |
Pressure
(mb) |
Wind Speed
(kt) | 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.
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