Tropical Cyclone Report

Hurricane Kristy

(EP122006)

30 August - 8 September 2006

Lixion A. Avila

National Hurricane Center

12 October 2006

Hurricane Kristy spent most of its lifetime over the tropical eastern
North Pacific.

a\. Synoptic History

Kristy developed from a tropical wave that crossed Dakar, Senegal on 13
August and was identified by a large swirl of low clouds and little
convection. The wave moved westward for two weeks across the Atlantic
Ocean, the Caribbean Sea and a good portion of the eastern North
Pacific. There was very little thunderstorm activity associated with the
wave until it reached Central America on 22 August. The wave continued
westward and it was not until 29 August that the shower activity became
persistent and began to show signs of organization. Based on Dvorak
classifications, it is estimated that a tropical depression formed at
0000 UTC 30 August about 520 n mi southwest of the southern tip of Baja
California. Six hours later, it became a tropical storm.

The cyclone strengthened further as it moved slowly toward the northwest
and became a hurricane at 0600 UTC 31 August. It reached its peak
intensity of 70 kt and a minimum pressure of 985 mb at 1200 UTC on the
same day, when an eye-like feature was observed on microwave imagery.
Thereafter, the steering currents collapsed and Kristy began to meander
for a while. It then weakened due to the northeasterly wind shear caused
by the outflow associated with Hurricane John which was approaching Baja
California. The high pressure ridge built to the north of the cyclone
and Kristy began to move slowly westward fluctuating in intensity
between storm and depression status until 0600 UTC 8 August when it
became a remnant low. The low continued to move slowly westward and
degenerated into a wave on the 9 September.

The "best track" chart of the tropical cyclone's path is given in Fig.
1, with the wind and pressure histories shown in Figs. 2 and 3,
respectively. The best track positions and intensities are listed in
Table 1.

b.  Meteorological Statistics

    Observations in Kristy (Figs. 2 and 3) include satellite-based
    Dvorak technique intensity estimates from the Tropical Analysis and
    Forecast Branch (TAFB), the Satellite Analysis Branch (SAB) and
    the U. S. Air Force Weather Agency (AFWA). Microwave satellite
    imagery from NOAA polar-orbiting satellites, the NASA Tropical
    Rainfall Measuring Mission (TRMM), the NASA QuikSCAT, and Defense
    Meteorological Satellite Program (DMSP) satellites were also useful
    in tracking Kristy. The 70-kt peak intensity was based on the
    average of the Dvorak T-numbers.

c\. Casualty and Damage Statistics

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

d\. Forecast and Warning Critique

The description of the disturbance from which Kristy originated was
included in Tropical Weather Outlooks (TWO) products beginning on 28
August. However, the possibility of tropical cyclone formation was not
mentioned in the TWO until 4 PM PDT 29 August, just two hours before
Kristy formed.

Average official track errors (with the number of cases in parentheses)
for Kristy were 36 (35), 66 (33), 96 (31), 122 (28), 196 (18), 284 (10)
and 317 (10) n mi for the 12, 24, 36, 48, 72, 96, and 120 h forecasts,
respectively. These errors are above the average official track errors
for the 5-yr period 2001-2005 of 35, 60, 83, 103, 145, 192, and 231 n
mi, respectively. Table 2 displays the forecast track model statistics
and shows the comparison with the official forecast track.

Average official intensity errors were 5, 9, 12, 13, 11, 8 and 8 knots
for the 12, 24, 36, 48, 72, 96 and 120 h forecasts, respectively. These
errors are much lower than the long-term averages of 6, 11, 14, 17, 19,
18, and 19 knots for the same 5-yr period. Table 3 includes the forecast
intensity model statistics as well as the average official intensity
forecast errors. With the exception of the 4 and 5 day forecasts, the
models performed better than the official forecast errors.

No watches or warnings were required for Kristy.

Table 1. Best track for Hurricane Kristy, 30 August -- 8 September 2006.

+-----------+-----------+---------+---------+---------+--------------+
| Date/Time | Latitude  | Lo      | P       | Wind    | Stage        |
|           |           | ngitude | ressure | Speed   |              |
| (UTC)     | (°N)      |         |         |         |              |
|           |           | (°W)    | (mb)    | (kt)    |              |
+-----------+-----------+---------+---------+---------+--------------+
| 30 / 0000 | 16.0      | 114.0   | 1007    | 30      | tropical     |
|           |           |         |         |         | depression   |
+-----------+-----------+---------+---------+---------+--------------+
| 30 / 0600 | 16.3      | 114.4   | 1005    | 35      | tropical     |
|           |           |         |         |         | storm        |
+-----------+-----------+---------+---------+---------+--------------+
| 30 / 1200 | 16.5      | 114.9   | 1000    | 50      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 30 / 1800 | 16.7      | 115.2   | 994     | 55      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 31 / 0000 | 17.0      | 115.5   | 990     | 60      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 31 / 0600 | 17.4      | 115.9   | 987     | 65      | hurricane    |
+-----------+-----------+---------+---------+---------+--------------+
| 31 / 1200 | 17.8      | 116.4   | 985     | 70      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 31 / 1800 | 18.2      | 116.9   | 987     | 65      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 01 / 0000 | 18.7      | 117.4   | 990     | 65      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 01 / 0600 | 19.0      | 117.9   | 992     | 60      | tropical     |
|           |           |         |         |         | storm        |
+-----------+-----------+---------+---------+---------+--------------+
| 01 / 1200 | 19.0      | 118.2   | 995     | 50      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 01 / 1800 | 19.0      | 118.6   | 998     | 45      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 02 / 0000 | 19.0      | 118.7   | 1003    | 40      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 02 / 0600 | 18.9      | 118.8   | 1004    | 35      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 02 / 1200 | 18.7      | 118.8   | 1005    | 35      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 02 / 1800 | 18.4      | 118.7   | 1007    | 30      | tropical     |
|           |           |         |         |         | depression   |
+-----------+-----------+---------+---------+---------+--------------+
| 03 / 0000 | 18.3      | 118.5   | 1009    | 30      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 03 / 0600 | 18.2      | 118.3   | 1009    | 30      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 03 / 1200 | 18.1      | 118.1   | 1009    | 30      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 03 / 1800 | 17.8      | 118.1   | 1005    | 35      | tropical     |
|           |           |         |         |         | storm        |
+-----------+-----------+---------+---------+---------+--------------+
| 04 / 0000 | 17.7      | 118.3   | 1006    | 35      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 04 / 0600 | 17.1      | 118.3   | 1007    | 30      | tropical     |
|           |           |         |         |         | depression   |
+-----------+-----------+---------+---------+---------+--------------+
| 04 / 1200 | 16.8      | 118.7   | 1007    | 30      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 04 / 1800 | 16.4      | 119.1   | 1007    | 30      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 05 / 0000 | 16.2      | 119.5   | 1007    | 30      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 05 / 0600 | 16.2      | 120.2   | 1007    | 30      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 05 / 1200 | 16.3      | 121.1   | 1005    | 35      | tropical     |
|           |           |         |         |         | storm        |
+-----------+-----------+---------+---------+---------+--------------+
| 05 / 1800 | 16.5      | 122.3   | 1003    | 35      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 06 / 0000 | 16.5      | 123.5   | 1004    | 35      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 06 / 0600 | 16.5      | 124.8   | 1005    | 35      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 06 / 1200 | 16.5      | 126.1   | 1007    | 30      | tropical     |
|           |           |         |         |         | depression   |
+-----------+-----------+---------+---------+---------+--------------+
| 06 / 1800 | 16.5      | 127.3   | 1007    | 30      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 07 / 0000 | 16.4      | 128.2   | 1007    | 30      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 07 / 0600 | 16.3      | 129.0   | 1008    | 25      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 07 / 1200 | 16.2      | 129.6   | 1009    | 25      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 07 / 1800 | 16.0      | 130.1   | 1009    | 25      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 08 / 0000 | 15.5      | 130.9   | 1009    | 25      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 08 / 0600 | 15.2      | 131.4   | 1009    | 20      | remnant low  |
+-----------+-----------+---------+---------+---------+--------------+
| 08 / 1200 | 15.0      | 131.8   | 1009    | 20      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 08 / 1800 | 15.0      | 131.9   | 1009    | 20      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 09 / 0000 | 15.0      | 132.0   | 1009    | 20      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 09 / 0600 | 15.0      | 132.5   | 1009    | 20      | \"           |
+-----------+-----------+---------+---------+---------+--------------+
| 09 / 1200 |           |         |         |         | dissipated   |
+-----------+-----------+---------+---------+---------+--------------+
| 31 / 1200 | 17.8      | 116.4   | 985     | 70      | minimum      |
|           |           |         |         |         | pressure     |
+-----------+-----------+---------+---------+---------+--------------+

Table. 2. Preliminary forecast evaluation (heterogeneous sample) for
Hurricane Kristy, 30 August - 8 September 2006. Forecast errors (n mi)
are followed by the number of forecasts in parentheses. Errors smaller
than the NHC official forecast are shown in bold-face type. Verification
includes the depression stage, but does not include the extratropical
stage.

+--------+--------+--------+--------+--------+-------+-------+-------+
| Fo     | Fo     |        |        |        |       |       |       |
| recast | recast |        |        |        |       |       |       |
| Tec    | Period |        |        |        |       |       |       |
| hnique | (h)    |        |        |        |       |       |       |
+========+========+========+========+========+=======+=======+=======+
|        | 12     | 24     | 36     | 48     | 72    | 96    | 120   |
+--------+--------+--------+--------+--------+-------+-------+-------+
| CLP5   | 40     | 83     | 126    | 176    | 299   | 418   | 475   |
|        | (35)   | (33)   | (31)   | (29)   | (25)  | (21)  | (17)  |
+--------+--------+--------+--------+--------+-------+-------+-------+
| GFNI   | 48     | 110    | 190    | 276    | 568 ( | 541 ( | 628 ( |
|        | (33)   | (31)   | (29)   | (22)   | 9)    | 4)    | 2)    |
+--------+--------+--------+--------+--------+-------+-------+-------+
| GFDI   | 42     | 77     | 113    | 137    | 197   | 288   | 349   |
|        | (35)   | (33)   | (31)   | (29)   | (25)  | (21)  | (17)  |
+--------+--------+--------+--------+--------+-------+-------+-------+
| GFSI   | 43     | 75     | 102    | 124    | **177 | **268 | 499 ( |
|        | (33)   | (30)   | (29)   | (24)   | (     | (     | 2)    |
|        |        |        |        |        | 15)** | 5**)  |       |
+--------+--------+--------+--------+--------+-------+-------+-------+
| AEMI   | 43     | 66     | **87   | **108  | 197   | 425 ( | 581 ( |
|        | (35)   | (30)   | (29)** | (28)** | (15)  | 7)    | 3)    |
+--------+--------+--------+--------+--------+-------+-------+-------+
| NGPI   | 47     | 99     | 158    | 222    | 283   | 286   | 344   |
|        | (35)   | (33)   | (31)   | (29)   | (23)  | (17)  | (10)  |
+--------+--------+--------+--------+--------+-------+-------+-------+
| UKMI   | 38     | 70     | 102    | 125    | **182 | **272 | 295 ( |
|        | (32)   | (30)   | (28)   | (26)   | (     | (     | 2)    |
|        |        |        |        |        | 14)** | 6)**  |       |
+--------+--------+--------+--------+--------+-------+-------+-------+
| BAMD   | 60     | 114    | 167    | 220    | 365   | 549   | 708   |
|        | (34)   | (32)   | (30)   | (28)   | (24)  | (20)  | (17)  |
+--------+--------+--------+--------+--------+-------+-------+-------+
| BAMM   | 49     | 85     | 116    | 149    | 256   | 400   | 535   |
|        | (34)   | (32)   | (30)   | (28)   | (24)  | (20)  | (17)  |
+--------+--------+--------+--------+--------+-------+-------+-------+
| BAMS   | 45     | 78     | 106    | 126    | **192 | 296   | 403   |
|        | (35)   | (33)   | (31)   | (29)   | (     | (21)  | (17)  |
|        |        |        |        |        | 25)** |       |       |
+--------+--------+--------+--------+--------+-------+-------+-------+
| CONU   | **35   | 66     | **95   | **119  | **153 | **229 | **297 |
|        | (35)** | (33)   | (31)** | (29)** | (     | (     | (     |
|        |        |        |        |        | 25)** | 19)** | 12)** |
+--------+--------+--------+--------+--------+-------+-------+-------+
| GUNA   | 37     | 67     | **91   | **105  | **134 |       |       |
|        | (30)   | (27)   | (26)** | (21)** | (     |       |       |
|        |        |        |        |        | 8)**  |       |       |
+--------+--------+--------+--------+--------+-------+-------+-------+
| FSSE   | **35   | **63   | **89   | **103  | **155 | **244 | **315 |
|        | (24)** | (24)** | (23)** | (21)** | (     | (     | (     |
|        |        |        |        |        | 19)** | 12)** | 10)** |
+--------+--------+--------+--------+--------+-------+-------+-------+
| OFCL   | 36     | 66     | 96     | 122    | 196   | 284   | 317   |
|        | (35)   | (33)   | (31)   | (28)   | (18)  | (10)  | (10)  |
+--------+--------+--------+--------+--------+-------+-------+-------+
| NHC    | 35     | 60     | 83     | 103    | 145   | 192   | 231   |
| Of     | (1300) | (1152) | (1009) | (877)  | (652) | (465) | (313) |
| ficial |        |        |        |        |       |       |       |
|        |        |        |        |        |       |       |       |
| (200   |        |        |        |        |       |       |       |
| 1-2005 |        |        |        |        |       |       |       |
| mean)  |        |        |        |        |       |       |       |
+--------+--------+--------+--------+--------+-------+-------+-------+

Table 3. Preliminary intensity forecast evaluation (heterogeneous
sample) for Hurricane Kristy, 30 August - 8 September 2006. Forecast
errors (kt) are followed by the number of forecasts in parentheses.
Errors smaller than the NHC official forecast are shown in bold-face
type. Verification includes the depression stage, but does not include
the extratropical stage, if any.

+--------+-------+--------+--------+--------+-------+-------+-------+
| Fo     | For   |        |        |        |       |       |       |
| recast | ecast |        |        |        |       |       |       |
| Tec    | P     |        |        |        |       |       |       |
| hnique | eriod |        |        |        |       |       |       |
|        | (h)   |        |        |        |       |       |       |
+========+=======+========+========+========+=======+=======+=======+
|        | 12    | 24     | 36     | 48     | 72    | 96    | 120   |
+--------+-------+--------+--------+--------+-------+-------+-------+
| SHF5   | 5.4   | **8.6  | **11.9 | **12.7 | 19.4  | 20.6  | 18.0  |
|        | (35)  | (33)** | (31)** | (29)** | (25)  | (21)  | (17)  |
+--------+-------+--------+--------+--------+-------+-------+-------+
| GFDI   | 5.6   | **8.3  | **9.8  | **9.7  | **8.8 | **7.6 | **8.4 |
|        | (35)  | (33)** | (31)** | (29)** | (     | (     | (     |
|        |       |        |        |        | 25)** | 21)** | 16)** |
+--------+-------+--------+--------+--------+-------+-------+-------+
| SHIP   | 5.1   | **8.0  | **10.3 | **12.0 | 12.4  | 9.0   | **7.7 |
|        | (35)  | (33)** | (31)** | (29)** | (22)  | (17)  | (     |
|        |       |        |        |        |       |       | 12)** |
+--------+-------+--------+--------+--------+-------+-------+-------+
| DSHP   | 5.1   | **8.0  | **10.3 | **12.0 | 12.4  | 9.0   | **7.7 |
|        | (35)  | (33)** | (31)** | (29)** | (22)  | (17)  | (     |
|        |       |        |        |        |       |       | 12)** |
+--------+-------+--------+--------+--------+-------+-------+-------+
| FSSE   | 5.5   | **8.4  | **10.5 | **11.0 | *     | 10.8  | 14.0  |
|        | (24)  | (24)** | (23)** | (21)** | *10.8 | (12)  | (10)  |
|        |       |        |        |        | (     |       |       |
|        |       |        |        |        | 19)** |       |       |
+--------+-------+--------+--------+--------+-------+-------+-------+
| ICON   | **4.8 | **6.7  | **8.0  | **8.7  | **8.7 | **4.6 | **4.3 |
|        | (     | (32)** | (30)** | (28)** | (     | (     | (     |
|        | 34)** |        |        |        | 21)** | 16)** | 11)** |
+--------+-------+--------+--------+--------+-------+-------+-------+
| OFCL   | 5.0   | 9.7    | 12.3   | 13.4   | 11.1  | 8.0   | 8.0   |
|        | (35)  | (33)   | (31)   | (28)   | (18)  | (10)  | (10)  |
+--------+-------+--------+--------+--------+-------+-------+-------+
| NHC    | 6.2   | 10.8   | 14.3   | 16.5   | 18.7  | 18.3  | 19.3  |
| Of     | (     | (1152) | (1009) | (876)  | (652) | (465) | (313) |
| ficial | 1300) |        |        |        |       |       |       |
|        |       |        |        |        |       |       |       |
| (200   |       |        |        |        |       |       |       |
| 1-2005 |       |        |        |        |       |       |       |
| mean)  |       |        |        |        |       |       |       |
+--------+-------+--------+--------+--------+-------+-------+-------+

![](media/image1.wmf){width="6.493055555555555in"
height="5.052777777777778in"}

Figure 1. Best track positions for Hurricane Kristy 30 August - 8
September 2006.

![](media/image2.wmf){width="6.49375in" height="4.409722222222222in"}

Figure 2. Selected wind observations and best track maximum sustained
surface wind speed curve for Hurricane Kristy, 30 August - 8 September
2006

![](media/image3.wmf){width="6.49375in" height="4.5152777777777775in"}

Figure 3. Selected pressure observations and best track minimum central
pressure curve for Hurricane Kristy, 30 August- 8 September 2006.