Tropical Cyclone Report

Hurricane Fernanda

9-16 August 2005

Lixion A. Avila

National Hurricane Center

12 October 2005

Hurricane Fernanda spent most of its life over the ocean well away from
Mexico.

a\. Synoptic History

Fernanda developed from a tropical wave that crossed Dakar, Senegal on
25 July. The wave was well-defined in upper-air data and was accompanied
by a large area of thunderstorms. The wave was easily identified by
satellite as it moved westward across the tropical Atlantic and it
appeared to be in a developing phase as it crossed the Windward Islands
on 31 July. The development ceased when the system moved over South
America. The westward moving tropical wave crossed Central America and
convection began to redevelop gradually south of the Gulf of Tehuantepec
on 5 August. The wave continued westward, and it was not until 1200 UTC
9 August that the activity became organized enough to classify the
system as a tropical depression.

The convective pattern continued to become better organized and by 0000
UTC 10 August the system was designated Tropical Storm Fernanda. The
cyclone continued on a general west to west-northwest track and reached
hurricane status at 0600 UTC 11 August. Thereafter, there was just a
slight intensification and Fernanda reached its peak intensity of 75
knots and a minimum central pressure of 978 mb at 1200 UTC 12 August.
The cyclone developed a ragged eye during that time. Fernanda did not
change in intensity significantly during the next day and a half, and
thereafter, the northern half of the circulation moved over cooler
waters, resulting in a gradual weakening. Fernanda began to move toward
the west-southwest around a very strong subtropical ridge toward warmer
waters and the thunderstorm activity temporarily increased. However,
strong shear removed most of the deep convection from the center and the
cyclone became a depression at 1800 UTC 15 August. The cyclone then
weakened to a remnant low at 0600 UTC 16 August and continued moving
toward the west-southwest still producing intermittent convection until
dissipation. 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 Fernanda (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 Fernanda.

c\. Casualty and Damage Statistics

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

d\. Forecast and Warning Critique

Average official track errors (with the number of cases in parentheses)
for Fernanda were 19 (25), 28 (23), 41 (21), 54(19), 95(15), 126(11) and
173(7) n mi for the 12, 24, 36, 48, 72, 96, and 120 h forecasts,
respectively. These errors are well below the average official track
errors for the 10-yr period 1995-2004[^1] of 37, 68, 97, 123, 175, 208,
and 259 n mi, respectively. Table 2 displays the forecast track model
statistics and shows that comparison with the official forecast track.

Average official intensity errors were 7, 11, 11, 13, 15, 15 and 19
knots for the 12, 24, 36, 48, 72, 96 and 120 h forecasts, respectively.
These errors are very close to the long-term averages of 6, 11, 14, 17,
19, 18, and 19 knots for the same 10-yr period.

No watches or warnings were required for Fernanda.

Table 1. Best track for Tropical Storm Fernanda, 9-16 August 2005.

+-----------+-----------+--------+--------+-------+--------------------+
| Date/Time | Latitude  | Lon    | Pr     | Wind  | Stage              |
|           |           | gitude | essure | Speed |                    |
| (UTC)     | (°N)      |        |        |       |                    |
|           |           | (°W)   | (mb)   | (kt)  |                    |
+-----------+-----------+--------+--------+-------+--------------------+
| 09 / 1200 | 14.0      | 113.8  | 1006   | 25    | tropical           |
|           |           |        |        |       | depression         |
+-----------+-----------+--------+--------+-------+--------------------+
| 09 / 1800 | 14.3      | 114.8  | 1005   | 30    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 10 / 0000 | 14.8      | 115.8  | 1005   | 35    | tropical storm     |
+-----------+-----------+--------+--------+-------+--------------------+
| 10 / 0600 | 15.1      | 116.9  | 1000   | 45    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 10 / 1200 | 15.4      | 118.0  | 994    | 55    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 10 / 1800 | 15.6      | 118.6  | 994    | 55    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 11 / 0000 | 16.1      | 119.6  | 994    | 55    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 11 / 0600 | 16.3      | 120.2  | 989    | 65    | hurricane          |
+-----------+-----------+--------+--------+-------+--------------------+
| 11 / 1200 | 16.7      | 120.8  | 989    | 65    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 11 / 1800 | 17.1      | 121.6  | 986    | 65    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 12 / 0000 | 17.6      | 122.2  | 982    | 70    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 12 / 0600 | 17.9      | 122.6  | 979    | 75    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 12 / 1200 | 18.3      | 123.5  | 978    | 75    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 12 / 1800 | 18.6      | 124.3  | 979    | 75    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 13 / 0000 | 18.8      | 125.1  | 979    | 75    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 13 / 0600 | 19.1      | 126.0  | 979    | 75    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 13 / 1200 | 19.2      | 126.7  | 979    | 75    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 13 / 1800 | 19.2      | 127.5  | 983    | 65    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 14 / 0000 | 19.2      | 128.3  | 987    | 65    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 14 / 0600 | 19.0      | 129.0  | 990    | 60    | tropical storm     |
+-----------+-----------+--------+--------+-------+--------------------+
| 14 / 1200 | 18.7      | 129.6  | 990    | 60    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 14 / 1800 | 18.3      | 130.3  | 990    | 60    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 15 / 0000 | 17.9      | 131.0  | 990    | 60    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 15 / 0600 | 17.6      | 131.8  | 994    | 50    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 15 / 1200 | 17.3      | 132.6  | 1002   | 40    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 15 / 1800 | 17.1      | 133.7  | 1004   | 30    | tropical           |
|           |           |        |        |       | depression         |
+-----------+-----------+--------+--------+-------+--------------------+
| 16 / 0000 | 17.2      | 134.6  | 1008   | 25    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 16 / 0600 | 17.1      | 135.8  | 1008   | 20    | low                |
+-----------+-----------+--------+--------+-------+--------------------+
| 16 / 1200 | 17.0      | 137.0  | 1008   | 20    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 16 / 1800 | 16.8      | 138.0  | 1008   | 20    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 17 / 0000 | 16.6      | 139.0  | 1010   | 20    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 17 / 0600 | 16.5      | 140.0  | 1010   | 20    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 17 / 1200 | 16.4      | 141.0  | 1011   | 20    | \"                 |
+-----------+-----------+--------+--------+-------+--------------------+
| 17/ 1800  |           |        |        |       | dissipated         |
+-----------+-----------+--------+--------+-------+--------------------+
| 12 / 1200 | 18.3      | 123.5  | 978    | 75    | minimum pressure   |
+-----------+-----------+--------+--------+-------+--------------------+

Table. 2. Preliminary forecast evaluation (heterogeneous sample) for
Fernanda, 9-16 August 2005. 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.

  ---------------------------------------------------------------------------------------
  Forecast    Forecast                                                          
  Technique   Period (h)                                                        
  ----------- ---------- -------- -------- -------- -------- -------- --------- ---------
              12         24       36       48                72       96        120

  CLP5        27 (25)    54 (23)  88 (21)  122 19)  167 (15)          192 (11)  232 ( 7)

  GFNI        22 (22)    44 (20)  71 (18)  95 (16)  151 (12)          233 ( 8)  383 ( 4)

  GFDI        20 (24)    30 (22)  **38     54 (18)  97 (14)           157 (10)  241 ( 6)
                                  (20)**                                        

  GFDL        19 (25)    31 (23)  **33     **44     **82              138 (11)  224 ( 7)
                                  (21)**   (19)**   (15**)                      

  GFDN        28 (23)    42 (21)  **62     87 (17)  143 (13)          211 ( 9)  343 ( 5)
                                  (19)**                                        

  GFSI        20 (24)    30 (22)  **33     **47     **93              147 (10)  **126 (
                                  (20)**   (18)**   (14)**                      6)**

  GFSO        31 (25)    38 (23)  **36     **43     **80              **130     **129 (
                                  (21)**   (19)**   (15)**            (11**)    7)**

  AEMI        24 (24)    41 (22)  54 (20)  71 (18)  113 (14)          143 (10)  **170 (
                                                                                6)**

  NGPI        29 (24)    64 (22)  98 (20)  138 18)  222 (14)          323 (10)  399 ( 5)

  NGPS        28 (24)    50 (22)  82 (20)  122 18)  209 (14)          313 (10)  435 ( 6)

  UKMI        26 (24)    46 (22)  67 (20)  78 (18)  110 (14)          **100     **123 (
                                                                      (10)**    6)**

  UKM         25 (13)    46 (12)  52 (11)  73 (10)  111 ( 8)          **93 (    **99 (
                                                                      6)**      4)**

  BAMD        29 (25)    49 (23)  66 (21)  81 (19)  107 (15)          **135     **140 (
                                                                      (11)**    7)**

  BAMM        29 (24)    41 (22)  50 (20)  68 (18)  111 (15)          **130     **111 (
                                                                      (11)**    7)**

  BAMS        34 (24)    49 (22)  70 (20)  90 (18)  124 (15)          142 (11)  **136 (
                                                                                7)**

  CONU        **17       **27     **38     55 (18)  **94              148 (10)  193 ( 6)
              (24)**     (22)**   (20)**            (14)**                      

  GUNA        **15       **22     **34     **45     **85              138 ( 9)  177 ( 5)
              (23)**     (21)**   (19)**   (17)**   (13)**                      

  FSSE        19 (24)    39 (22)  61 (20)  86 (18)  124 (14)          183 ( 9)  208 ( 5)

  OFCL        19 (25)    28 (23)  41 (21)  54 (19)  95 (15)           136 (11)  173 ( 7)
  ---------------------------------------------------------------------------------------

![](media/image1.wmf){width="5.7375in" height="4.464583333333334in"}

Figure 1. Best track positions for Hurricane Fernanda 9-16 August 2005.

![](media/image2.wmf){width="6.49375in" height="4.5152777777777775in"}

Figure 2. Selected wind observations and best track maximum sustained
surface wind speed curve for Hurricane Fernanda, 9-16 August 2005

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

Figure 3. Selected pressure observations and best track minimum central
pressure curve for Hurricane Fernanda, 9-16 August, 2005.

[^1]: Errors given for the 96 and 120 h periods are averages over the
    four-year period 2001-4.