Number range CHAPTERTropical Cyclone Report

Tropical Storm Calvin

26-29 June 2005

Jack Beven

National Hurricane Center

28 November 2005

a.  Synoptic History

    Calvin formed from a tropical wave that emerged from the west coast
    of Africa on 11 June. The wave moved westward with little associated
    shower activity until it reached the southwestern Caribbean Sea on
    19 June. The associated convection increased on 20-21 June while the
    wave crossed Central America into the eastern Pacific. By 24-25
    June, the wave was passing south of the Gulf of Tehuantepec and the
    convection was showing increasing organization. It is estimated that
    a tropical depression formed around 0600 UTC 26 June about 285 n mi
    south-southeast of Acapulco, Mexico. 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.

    The depression initially moved north-northwestward, and it
    intensified into a tropical storm later that day. Calvin turned
    west-northwestward on 27 June while reaching an estimated peak
    intensity of 45 kt. On 28 June, the cyclone then made a gradual turn
    toward the west-southwest and weakened as easterly vertical shear
    separated the convection from the low-level center. Calvin became a
    depression on 28 June, and it degenerated to a remnant low on 29
    June as it turned westward. The low turned west-northwestward on 30
    June as a transient re-development of convection occurred -- one
    that lacked sufficient organization or longevity to again call
    Calvin a tropical cyclone. The low moved northwestward with some
    acceleration on 1 July, then turned westward on the south side of a
    strong low-level ridge on 2 July. The low dissipated on 3 July about
    680 n mi west-southwest of Cabo San Lucas, Mexico.

b.  Meteorological Statistics

    Observations in Calvin (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 Aqua, the NASA QuikSCAT,
    the Department of Defense WindSat, and Defense Meteorological
    Satellite Program (DMSP) satellites were also useful in tracking
    Calvin.

    There were two ship reports of tropical storm-force winds from
    Calvin. The **Saga Wind** reported 34-kt winds at 1800 UTC 26 June,
    while the **ITB New York** reported 34-kt winds at 0900 UTC 27 June.

c.  Casualty and Damage Statistics

    There were no reports of damages or casualties associated with
    Calvin.

d.  Forecast and Warning Critique

    Calvin was a tropical cyclone for only 66 h, so there are relatively
    few forecasts to verify. Average official forecast track errors
    (with the number of cases in parentheses) were 44 (8), 68 (6), 78
    (4), and 102 (2) n mi for the 12, 24, 36, and 48 h forecasts,
    respectively. These errors are greater than the average official
    track errors for the 10-yr period 1995-2004[^1] at 12 h, equal to
    the 10-yr average at 24 h, and less than the average errors at 24-48
    h (37, 68, 97, and 123 n mi, respectively).

    Average official intensity errors were 9, 13, 26, and 40 kt for the
    12, 24, 36, and 48 h forecasts, respectively. For comparison, the
    average official intensity errors over the 10-yr period 1995-2004
    are 6, 11, 14, and 17 kt, respectively. The 40-kt error at 48 h
    resulted from forecasts that anticipated that Calvin would become a
    hurricane.

    A tropical storm watch was issued for the coast of Mexico from
    Lagunas de Chachua to Lazaro Cardenas at 0300 UTC 27 June. At 0300
    UTC 28 June, the watch was shifted westward to cover the coast from
    Acapulco to Manzanillo. The watch was discontinued at 1500 UTC 28
    June.

Number range CHAPTERTable 1. Best track for Tropical Storm Calvin, 26-29
June 2005.

+---------+---------+---------+---------+---------+-----------------+
| Da      | L       | Lo      | P       | Wind    | Stage           |
| te/Time | atitude | ngitude | ressure | Speed   |                 |
|         |         |         |         |         |                 |
| (UTC)   | (N)    | (W)    | (mb)    | (kt)    |                 |
+---------+---------+---------+---------+---------+-----------------+
| 26 /    | 12.7    | 97.2    | 1004    | 25      | tropical        |
| 0600    |         |         |         |         | depression      |
+---------+---------+---------+---------+---------+-----------------+
| 26 /    | 13.0    | 97.7    | 1004    | 25      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 26 /    | 13.5    | 97.9    | 1003    | 35      | tropical storm  |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 27 /    | 14.0    | 98.0    | 1003    | 35      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 27 /    | 14.4    | 98.4    | 1001    | 40      | \"              |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 27 /    | 14.7    | 99.4    | 1000    | 45      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 27 /    | 15.1    | 100.2   | 1000    | 45      | \"              |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 28 /    | 15.5    | 101.1   | 1002    | 40      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 28 /    | 15.8    | 102.3   | 1004    | 35      | \"              |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 28 /    | 15.9    | 103.6   | 1005    | 30      | tropical        |
| 1200    |         |         |         |         | depression      |
+---------+---------+---------+---------+---------+-----------------+
| 28 /    | 15.5    | 104.4   | 1006    | 25      | \"              |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 29 /    | 15.1    | 105.1   | 1006    | 25      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 29 /    | 14.7    | 105.4   | 1006    | 20      | remnant low     |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 29 /    | 14.5    | 105.9   | 1005    | 20      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 29 /    | 14.5    | 106.7   | 1004    | 20      | \"              |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 30 /    | 14.7    | 107.5   | 1003    | 25      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 30 /    | 14.8    | 108.0   | 1005    | 25      | \"              |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 30 /    | 15.0    | 108.3   | 1006    | 25      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 30 /    | 15.4    | 108.7   | 1006    | 25      | \"              |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 01 /    | 15.9    | 109.3   | 1006    | 25      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 01 /    | 17.0    | 110.0   | 1006    | 25      | \"              |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 01 /    | 18.0    | 110.9   | 1006    | 25      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 01 /    | 18.7    | 112.2   | 1006    | 20      | \"              |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 02 /    | 19.3    | 113.5   | 1006    | 20      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 02 /    | 20.2    | 114.5   | 1006    | 20      | \"              |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 02 /    | 21.0    | 115.6   | 1007    | 20      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 02 /    | 21.2    | 117.1   | 1008    | 20      | \"              |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 03 /    | 21.2    | 118.7   | 1008    | 20      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 03 /    | 21.1    | 120.3   | 1009    | 20      | \"              |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 03 /    | 21.0    | 122.0   | 1009    | 20      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 03 /    |         |         |         |         | dissipated      |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 27 /    | 14.7    | 99.4    | 1000    | 45      | minimum         |
| 1200    |         |         |         |         | pressure        |
+---------+---------+---------+---------+---------+-----------------+

![](media/image1.wmf){width="7.895833333333333in"
height="6.301388888888889in"}

Number range CHAPTERFigure 1. Best track positions for Tropical Storm
Calvin, 26 -- 29 June 2005.

![](media/image2.wmf){width="8.621527777777779in"
height="5.903472222222222in"}

Number range CHAPTERFigure 2. Selected wind observations and best track
maximum sustained surface wind speed curve for Tropical Storm Calvin, 26
-- 29 June 2005. Objective Dvorak estimates represent linear averages
over a three-hour period centered on the nominal observation time.

![](media/image3.wmf){width="8.65in" height="5.898611111111111in"}

Number range CHAPTERFigure 3. Selected pressure observations and best
track minimum central pressure curve for Tropical Storm Calvin, 26 -- 29
June 2005. Objective Dvorak estimates represent linear averages over a
three-hour period centered on the nominal observation time.

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