Tropical Cyclone Report

Hurricane Boris

(EP022008)

27 June- 4 July 2008

Eric S. Blake

National Hurricane Center

17 October 2008

Boris was a category one hurricane that followed a typical early summer
path far offshore of southwestern Mexico.

a.  Synoptic History

The easterly wave that spawned Boris left the African coast on 14 June.
The wave moved across the Atlantic basin in about a week, showing few
signs of development before it entered the eastern Pacific on 22 June. A
broad surface low formed the next day south of the Gulf of Tehuantepec
as the convective organization increased. Thunderstorms consolidated
near the center of the low late on 26 June, and the system acquired
enough organization to become a tropical depression around 0600 UTC 27
June, centered about 525 n mi south-southwest of Manzanillo, 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.

High pressure to the north of the tropical cyclone initially steered the
system to the west-northwest, then more to the west as the high
strengthened. Moderate easterly wind shear was light enough to allow the
depression to become a tropical storm six hours after formation. The
moderate shear, however, prevented much intensification of Boris for the
next day or so. The shear lessened early on 29 June, and Boris slowly
strengthened. The tropical cyclone was near hurricane strength on 30
June when a ragged eye feature became apparent in satellite imagery, and
it became a hurricane on the next day. The hurricane briefly weakened
late on 1 July, but it restrengthened on 2 July, turned to the
west-northwest and reached a peak intensity of about 70 kt. However,
cold water and a relatively stable atmosphere contributed to a fast
demise of Boris. Convection rapidly diminished near the system on 3 July
and the system weakened to a tropical depression early on 4 July,
becoming a remnant low later that day about 1270 n mi west-southwest of
the southern tip of Baja California. The low moved west to
west-southwest for a couple of days, eventually dissipating on 6 July
just before entering the central Pacific Ocean.

b.  Meteorological Statistics

    Observations in Boris (Figs. 2 and 3) include satellite-based Dvorak
    technique intensity estimates from the Tropical Analysis and
    Forecast Branch (TAFB) and the Satellite Analysis Branch (SAB).
    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,
    among others, were also useful in tracking the storm. The peak
    intensity of 70 kt is based on a blend of satellite estimates from
    TAFB and SAB. The intensity of Boris after peak intensity was based
    on a blend of Dvorak T/CI numbers from TAFB and SAB. There were no
    reports of tropical-storm force winds received from ships.

c.  Casualty and Damage Statistics

    There were no reports of damages or deaths related to Boris.

d.  Forecast and Warning Critique

    The genesis of Boris was well-anticipated. The system was first
    mentioned in the Tropical Weather Outlook products almost 60 hours
    before it developed, and the possibility of the system becoming a
    tropical depression was explicitly included about 18 hours before
    formation.

    The average official track errors for Boris were 28, 52, 73, 100,
    152, 170 and 158 n mi for the 12, 24, 36, 48, 72, 96, 120 h
    forecasts, respectively. The number of forecasts ranged from 27 at
    12 h to 9 at 120 h. These forecast errors were near the five-year
    average official track errors through 72 h (Table 2), and little
    smaller than that average thereafter. The official forecast was an
    improvement on most of the guidance except for the variable
    consensus models (TVCN, TVCC) through 72 hr.

    Average official intensity errors were 7, 9, 13, 16, 22, 23, and 19
    kt for the 12, 24, 36, 48, 72, 96, 120 h forecasts, respectively.
    These errors are generally a little larger than the long-term
    average, especially at 72 and 96 h. In sharp contrast to the track
    forecast errors, almost all of the available guidance was better
    than the official NHC forecast, which had a pronounced low bias. The
    system intensified much more than anticipated in NHC forecasts,
    which were based on the expectation that the shear would be too
    strong to allow significant intensification. The best guidance at
    long-range was the climatology and persistence model (SHF5).

Table 1. Best track for Hurricane Boris, 27 June- 4 July 2008.

+---------+--------+-----------+--------+------------+----------------+
| Da      | La     | Longitude | Pr     | Wind Speed | Stage          |
| te/Time | titude |           | essure |            |                |
|         |        | \(W\)     |        | (kt)       |                |
| (UTC)   | \(N\)  |           | (mb)   |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 27 /    | 12.2   | 107.9     | 1006   | 30         | tropical       |
| 0600    |        |           |        |            | depression     |
+---------+--------+-----------+--------+------------+----------------+
| 27 /    | 12.6   | 108.7     | 1005   | 35         | tropical storm |
| 1200    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 27 /    | 13.0   | 109.5     | 1000   | 45         | \"             |
| 1800    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 28 /    | 13.5   | 110.5     | 997    | 50         | \"             |
| 0000    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 28 /    | 14.0   | 111.5     | 997    | 50         | \"             |
| 0600    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 28 /    | 14.4   | 112.5     | 1000   | 45         | \"             |
| 1200    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 28 /    | 14.7   | 113.4     | 1000   | 45         | \"             |
| 1800    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 29 /    | 14.9   | 114.2     | 1000   | 45         | \"             |
| 0000    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 29 /    | 15.0   | 115.0     | 1000   | 45         | \"             |
| 0600    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 29 /    | 14.9   | 115.8     | 997    | 50         | \"             |
| 1200    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 29 /    | 14.8   | 116.8     | 995    | 55         | \"             |
| 1800    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 30 /    | 14.8   | 117.9     | 992    | 60         | \"             |
| 0000    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 30 /    | 14.9   | 119.0     | 992    | 60         | \"             |
| 0600    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 30 /    | 14.9   | 120.2     | 992    | 60         | \"             |
| 1200    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 30 /    | 14.8   | 121.4     | 992    | 60         | \"             |
| 1800    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 01 /    | 14.7   | 122.5     | 989    | 65         | hurricane      |
| 0000    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 01 /    | 14.6   | 123.5     | 989    | 65         | \"             |
| 0600    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 01 /    | 14.7   | 124.3     | 989    | 65         | \"             |
| 1200    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 01 /    | 14.9   | 125.0     | 991    | 60         | tropical storm |
| 1800    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 02 /    | 15.3   | 125.6     | 988    | 65         | hurricane      |
| 0000    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 02 /    | 15.7   | 126.2     | 985    | 70         | \"             |
| 0600    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 02 /    | 16.2   | 126.9     | 988    | 65         | \"             |
| 1200    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 02 /    | 16.6   | 127.4     | 992    | 55         | tropical storm |
| 1800    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 03 /    | 16.9   | 127.9     | 995    | 50         | \"             |
| 0000    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 03 /    | 17.2   | 128.4     | 995    | 50         | \"             |
| 0600    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 03 /    | 17.3   | 129.0     | 1000   | 40         | \"             |
| 1200    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 03 /    | 17.3   | 129.6     | 1002   | 35         | \"             |
| 1800    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 04 /    | 17.2   | 130.2     | 1003   | 30         | tropical       |
| 0000    |        |           |        |            | depression     |
+---------+--------+-----------+--------+------------+----------------+
| 04 /    | 17.1   | 130.8     | 1005   | 25         | \"             |
| 0600    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 04 /    | 17.0   | 131.5     | 1006   | 20         | low            |
| 1200    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 04 /    | 16.8   | 132.4     | 1007   | 20         | \"             |
| 1800    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 05 /    | 16.5   | 133.2     | 1007   | 20         | \"             |
| 0000    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 05 /    | 16.2   | 134.1     | 1007   | 20         | \"             |
| 0600    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 05 /    | 16.0   | 135.0     | 1007   | 20         | \"             |
| 1200    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 05 /    | 16.0   | 136.2     | 1007   | 20         | \"             |
| 1800    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 06 /    | 15.9   | 137.2     | 1007   | 20         | \"             |
| 0000    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 06 /    | 15.8   | 138.0     | 1008   | 20         | \"             |
| 0600    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 06 /    | \-     | \-        | \-     | \-         | dissipated     |
| 1200    |        |           |        |            |                |
+---------+--------+-----------+--------+------------+----------------+
| 02 /    | 15.7   | 126.2     | 985    | 70         | minimum        |
| 0600    |        |           |        |            | pressure       |
+---------+--------+-----------+--------+------------+----------------+

Table 2. Track forecast evaluation (heterogeneous sample) for Hurricane
Boris, 27 June- 4 July 2008. Forecast errors (n mi) are followed by the
number of forecasts in parentheses. Errors smaller than the NHC official
forecast are shown in boldface type.

+-----------+-------+-------+-------+-------+-------+-------+-------+
| Forecast  | For   |       |       |       |       |       |       |
| Technique | ecast |       |       |       |       |       |       |
|           | P     |       |       |       |       |       |       |
|           | eriod |       |       |       |       |       |       |
|           | (h)   |       |       |       |       |       |       |
+===========+=======+=======+=======+=======+=======+=======+=======+
|           | 12    | 24    | 36    | 48    | 72    | 96    | 120   |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CLP5      | 35    | 70    | 103   | 132   | 189   | **163 | 173 ( |
|           | (27)  | (25)  | (23)  | (21)  | (17)  | (     | 9)    |
|           |       |       |       |       |       | 13)** |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFNI      | 34    | 77    | 121   | 150   | 223   | 319   | 550 ( |
|           | (25)  | (23)  | (21)  | (18)  | (14)  | (10)  | 6)    |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDI      | 32    | 61    | 87    | 115   | 201   | 353   | 448 ( |
|           | (27)  | (25)  | (23)  | (21)  | (17)  | (13)  | 9)    |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| HWFI      | 30    | 57    | 83    | 107   | 161   | 175   | 254 ( |
|           | (27)  | (25)  | (23)  | (21)  | (17)  | (13)  | 9)    |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFSI      | 40    | 79    | 132   | 206   | 350   | 488 ( | 573 ( |
|           | (27)  | (25)  | (23)  | (20)  | (15)  | 6)    | 5)    |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| AEMI      | 40    | 82    | 138   | 202   | 335   |       |       |
|           | (27)  | (25)  | (23)  | (21)  | (16)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NGPI      | 30    | 57    | 90    | 127   | 203   | 315   | 410 ( |
|           | (25)  | (23)  | (21)  | (19)  | (15)  | (11)  | 6)    |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| UKMI      | 34    | 62    | 86    | 115   | 202   | 245 ( | 1380  |
|           | (25)  | (23)  | (21)  | (19)  | (11)  | 5)    | ( 2)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| EMXI      | 33    | 55    | 82    | 109   | 190 ( | 358 ( | 565 ( |
|           | (17)  | (16)  | (14)  | (12)  | 8)    | 5)    | 2)    |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMD      | 36    | 62    | 86    | 121   | 205   | 280   | 386 ( |
|           | (27)  | (25)  | (23)  | (21)  | (17)  | (13)  | 9)    |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMM      | 32    | **50  | **72  | 108   | 205   | 360   | 464 ( |
|           | (27)  | (     | (     | (21)  | (17)  | (13)  | 9)    |
|           |       | 25)** | 23)** |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMS      | 34    | 58    | 77    | 100   | 171   | 251   | 333 ( |
|           | (27)  | (25)  | (23)  | (21)  | (17)  | (13)  | 9)    |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| TVCN      | **27  | **48  | **70  | **91  | **147 | 213   | 300 ( |
|           | (     | (     | (     | (     | (     | (13)  | 9)    |
|           | 27)** | 25)** | 23)** | 21)** | 17)** |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| TVCC      | 30    | **48  | **68  | **91  | **116 | 221   | 266   |
|           | (27)  | (     | (     | (     | (     | (13)  | (9)   |
|           |       | 25)** | 23)** | 21)** | 17)** |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GUNA      | **26  | **47  | **71  | 106   | 203 ( | 534 ( |       |
|           | (     | (     | (     | (18)  | 7)    | 1)    |       |
|           | 25)** | 23)** | 21)** |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| FSSE      | 29    | 54    | 78    | 101   | 166   | 235   | 288 ( |
|           | (25)  | (23)  | (21)  | (20)  | (15)  | (10)  | 4)    |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| OFCL      | 28    | 52    | 73    | 100   | 152   | 170   | 158 ( |
|           | (27)  | (25)  | (23)  | (21)  | (17)  | (13)  | 9)    |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NHC       | 31.9  | 55.1  | 77.4  | 97.9  | 136.2 | 180.1 | 226.1 |
| Official  | (     | (     | (979) | (849) | (620) | (439) | (293) |
|           | 1282) | 1129) |       |       |       |       |       |
| (         |       |       |       |       |       |       |       |
| 2003-2007 |       |       |       |       |       |       |       |
| mean)     |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+

Table 3. Intensity forecast evaluation (heterogeneous sample) for
Hurricane Boris, 27 June- 4 July 2008. Forecast errors (kt) are followed
by the number of forecasts in parentheses. Errors smaller than the NHC
official forecast are shown in boldface type.

+----------+-------+--------+-------+--------+-------+-------+-------+
| Forecast | For   |        |       |        |       |       |       |
| T        | ecast |        |       |        |       |       |       |
| echnique | P     |        |       |        |       |       |       |
|          | eriod |        |       |        |       |       |       |
|          | (h)   |        |       |        |       |       |       |
+==========+=======+========+=======+========+=======+=======+=======+
|          | 12    | 24     | 36    | 48     | 72    | 96    | 120   |
+----------+-------+--------+-------+--------+-------+-------+-------+
| SHF5     | 7.3   | **9.2  | *     | **12.5 | *     | *     | *     |
|          | (27)  | (25)** | *11.3 | (21)** | *12.4 | *12.5 | *10.2 |
|          |       |        | (     |        | (     | (     | (     |
|          |       |        | 23)** |        | 17)** | 13)** | 9)**  |
+----------+-------+--------+-------+--------+-------+-------+-------+
| GHMI     | **6.6 | **8.4  | *     | **11.9 | *     | *     | *     |
|          | (     | (25)** | *11.5 | (21)** | *15.6 | *19.8 | *16.4 |
|          | 27)** |        | (     |        | (     | (     | (     |
|          |       |        | 23)** |        | 17)** | 13)** | 9)**  |
+----------+-------+--------+-------+--------+-------+-------+-------+
| HWFI     | 7.6   | **8.7  | *     | **14.6 | *     | *     | *     |
|          | (27)  | (25)** | *10.4 | (21)** | *18.6 | *21.5 | *17.6 |
|          |       |        | (     |        | (     | (     | (     |
|          |       |        | 23)** |        | 17)** | 13)** | 9)**  |
+----------+-------+--------+-------+--------+-------+-------+-------+
| SHIP     | 7.2   | **9.3  | *     | **14.5 | *     | *     | *     |
|          | (27)  | (25)** | *12.7 | (21)** | *20.8 | *22.0 | *12.0 |
|          |       |        | (     |        | (     | (     | (     |
|          |       |        | 23)** |        | 17)** | 13)** | 9)**  |
+----------+-------+--------+-------+--------+-------+-------+-------+
| DSHP     | 7.2   | **9.3  | *     | **14.5 | *     | *     | *     |
|          | (27)  | (25)** | *12.7 | (21)** | *20.8 | *22.0 | *12.0 |
|          |       |        | (     |        | (     | (     | (     |
|          |       |        | 23)** |        | 17)** | 13)** | 9)**  |
+----------+-------+--------+-------+--------+-------+-------+-------+
| LGEM     | 7.6   | 10.8   | 14.0  | 17.5   | 22.9  | 25.0  | *     |
|          | (27)  | (25)   | (23)  | (21)   | (17)  | (13)  | *18.0 |
|          |       |        |       |        |       |       | (     |
|          |       |        |       |        |       |       | 9)**  |
+----------+-------+--------+-------+--------+-------+-------+-------+
| FSSE     | **6.4 | 9.6    | *     | **13.4 | *     | *     | 21.8  |
|          | (     | (23)   | *12.8 | (20)** | *15.1 | *19.6 | ( 4)  |
|          | 25)** |        | (     |        | (     | (     |       |
|          |       |        | 21)** |        | 15)** | 10)** |       |
+----------+-------+--------+-------+--------+-------+-------+-------+
| ICON     | **6.8 | **8.1  | *     | **13.6 | *     | *     | *     |
|          | (     | (24)** | *11.0 | (21)** | *19.1 | *21.1 | *13.2 |
|          | 26)** |        | (     |        | (     | (     | (     |
|          |       |        | 23)** |        | 17)** | 13)** | 9)**  |
+----------+-------+--------+-------+--------+-------+-------+-------+
| OFCL     | 7.2   | 9.4    | 13.3  | 16.0   | 21.5  | 22.7  | 18.9  |
|          | (27)  | (25)   | (23)  | (21)   | (17)  | (13)  | ( 9)  |
+----------+-------+--------+-------+--------+-------+-------+-------+
| NHC      | 6.2   | 10.4   | 13.9  | 16.3   | 18.7  | 19.2  | 19.1  |
| Official | (     |        |       |        | (620) | (439) | (293) |
|          | 1282) | \(     | \(    | \      |       |       |       |
| (2       |       | 1129\) | 979\) | (848\) |       |       |       |
| 003-2007 |       |        |       |        |       |       |       |
| mean)    |       |        |       |        |       |       |       |
+----------+-------+--------+-------+--------+-------+-------+-------+

![](media/image1.jpeg){width="7.754861111111111in"
height="5.983333333333333in"}

Figure 1. Best track positions for Hurricane Boris, 27 June- 4 July
2008.

![](media/image2.wmf){width="7.75in" height="6.054861111111111in"}

Figure 2. Selected wind observations and best track maximum sustained
surface wind speed curve for Hurricane Boris, 27 June- 4 July 2008.

![](media/image3.wmf){width="7.373611111111111in"
height="5.132638888888889in"}

Figure 3. Selected pressure observations and best track minimum central
pressure curve for Hurricane Boris, 27 June- 4 July 2008.