Tropical Cyclone Report

Tropical Storm Juliette

(EP142007)

29 September -- 2 October 2007

Robert Berg and Jamie R. Rhome

National Hurricane Center

8 November 2007

Juliette was a relatively short-lived tropical storm that took a
northwesterly track about 300 n mi off the Pacific coast of Mexico, its
center passing between Socorro and Clarion Islands.

a.  Synoptic History

Juliette formed from a tropical wave that moved off the coast of west
Africa early on 12 September. The wave became indistinct over the
central Atlantic Ocean during 17 -- 19 September as it interacted with
another slower-moving tropical wave located to its west, but it
ultimately became better defined on 20 September over the eastern
Caribbean. It then enhanced a pre-existing area of showers and
thunderstorms located over the western Caribbean on 22 September and
moved inland over Central America soon thereafter.

The southern portion of the wave emerged over the eastern Pacific Ocean
on 23 September and continued to move westward over the next few days
with showers and thunderstorms becoming more consolidated on 26
September. An area of low pressure developed along the wave axis around
1200 UTC 27 September, approximately 300 n mi southwest of Acapulco,
Mexico. Deep convection gradually became better organized near the low
during the next day or so, and a tropical depression is estimated to
have formed at 0000 UTC 29 September, centered about 365 n mi southwest
of Manzanillo, Mexico. The depression intensified to a tropical storm
about 12 h later, becoming the tenth tropical storm of the 2007 Eastern
Pacific season---about one month later than the average date of
formation for the tenth tropical storm. The "best track" chart of
Juliette 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.

Juliette moved to the northwest over the next three days at a fairly
consistent speed of about 10 kt as it rounded the western periphery of a
mid-level ridge located over northern Mexico. The cyclone gradually
strengthened and reached a peak intensity of 50 kt at 1200 UTC 30
September as it passed between Socorro and Clarion Islands. The storm
then moved into an environment of strong southerly shear later that
evening as it approached a mid- to upper-level trough located to its
northwest. Combined with increasingly cooler waters and a more stable
air mass, the shear caused the low-level center to become separated from
the deep convection early on 1 October, and Juliette weakened to a
tropical depression later that day by 0000 UTC 2 October. No deep
convection redeveloped, and Juliette degenerated to a remnant low at
1200 UTC 2 October. The forward motion of the remnant circulation slowed
down considerably, and the low became nearly stationary for about 24 h
as it came under the influence of northwesterly flow associated with the
low-level subtropical ridge. The low eventually began to move to the
southeast, staying about 200 n mi west of the Baja Peninsula, and
ultimately degenerated to a trough at 0000 UTC 5 October.

b.  Meteorological Statistics

Observations in Juliette (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, the NASA Aqua, the
Department of Defense WINDSAT, and Defense Meteorological Satellite
Program (DMSP) satellites were also useful in tracking Juliette.
Juliette's estimated peak intensity of 50 kt is based on an average of
Dvorak intensity estimates from the TAFB and SAB.

There were no surface observations available from Socorro or Clarion
Islands during the passage of Juliette. In addition, no ship
observations with tropical storm force winds were received in the
vicinity of Juliette.

c.  Casualty and Damage Statistics

> There were no reports of casualties or damage associated with
> Juliette.

d.  Forecast and Warning Critique

The area of disturbed weather that ultimately became Tropical Storm
Juliette was first mentioned in the Tropical Weather Outlook (TWO)
issued by the National Hurricane Center at 1100 UTC 27 September, about
36 h prior to genesis. Explicit mention of the formation of a tropical
depression was included in the 2300 UTC 27 September TWO, about 24 h
prior to genesis. In addition, the Tropical Cyclone Danger Graphic
issued by the Tropical Analysis and Forecast Branch (TAFB) first
indicated that tropical cyclone formation was possible within the 48 h
window beginning at 0300 UTC 28 September.

A verification of official and guidance model track forecasts is given
in Table 2. Average official track errors for Juliette were 28, 40, 48,
83, and 213 n mi for the 12, 24, 36, 48, and 72 h forecasts,
respectively. Excluding the 72 h projection, for which there was only
one official forecast, these results are considerably better than the
long-term average of 33, 57, 79, 99, and 140 n mi for the 12, 24, 36, 48
and 72 h forecasts, respectively. The official forecasts were also
considerably better than all of the individual track models through 48
h. The CONU consensus was marginally better than the official forecast
at 48 h.

A verification of official and guidance model intensity forecasts is
given in Table 3. Average official intensity errors were 3, 4, 4, 4, and
10 kt for the 12, 24, 36, 48, and 72 h forecasts, respectively. For
comparison, the average long-term official intensity errors are 6, 11,
15, 17, and 19 kt, respectively. The intensity forecast errors were
below the long-term averages at all forecast times and beat all of the
individual intensity models through 36 h.

Number range CHAPTERTable 1. Best track for Tropical Storm Juliette, 29
September -- 2 October 2007.

+-----------+---------+---------+---------+---------+----------------+
| Date/Time | L       | Lo      | P       | Wind    | Stage          |
|           | atitude | ngitude | ressure | Speed   |                |
| (UTC)     |         |         |         |         |                |
|           | (°N)    | (°W)    | (mb)    | (kt)    |                |
+-----------+---------+---------+---------+---------+----------------+
| 29 / 0000 | 14.7    | 108.9   | 1006    | 30      | tropical       |
|           |         |         |         |         | depression     |
+-----------+---------+---------+---------+---------+----------------+
| 29 / 0600 | 15.0    | 110.0   | 1005    | 30      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 29 / 1200 | 15.4    | 110.9   | 1004    | 35      | tropical storm |
+-----------+---------+---------+---------+---------+----------------+
| 29 / 1800 | 16.0    | 111.7   | 1003    | 35      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 0000 | 16.7    | 112.2   | 1003    | 35      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 0600 | 17.4    | 112.6   | 1001    | 40      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 1200 | 18.1    | 113.0   | 997     | 50      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 1800 | 18.9    | 113.5   | 997     | 50      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 01 / 0000 | 19.7    | 114.0   | 1000    | 45      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 01 / 0600 | 20.5    | 114.6   | 1001    | 45      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 01 / 1200 | 21.4    | 115.1   | 1003    | 40      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 01 / 1800 | 22.3    | 115.4   | 1003    | 35      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 02 / 0000 | 23.1    | 115.8   | 1004    | 30      | tropical       |
|           |         |         |         |         | depression     |
+-----------+---------+---------+---------+---------+----------------+
| 02 / 0600 | 23.5    | 116.1   | 1005    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 02 / 1200 | 23.8    | 116.2   | 1006    | 25      | remnant low    |
+-----------+---------+---------+---------+---------+----------------+
| 02 / 1800 | 24.0    | 116.2   | 1006    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 03 / 0000 | 24.0    | 116.1   | 1006    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 03 / 0600 | 23.9    | 116.0   | 1006    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 03 / 1200 | 23.8    | 115.9   | 1006    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 03 / 1800 | 23.6    | 115.6   | 1007    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 04 / 0000 | 23.4    | 115.1   | 1007    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 04 / 0600 | 23.2    | 114.5   | 1007    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 04 / 1200 | 22.9    | 113.8   | 1007    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 04 / 1800 | 22.4    | 113.0   | 1008    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 05 / 0000 | 21.9    | 112.0   | 1008    | 25      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 05 / 0600 |         |         |         |         | dissipated     |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 1200 | 18.1    | 113.0   | 997     | 50      | minimum        |
|           |         |         |         |         | pressure       |
+-----------+---------+---------+---------+---------+----------------+

Number range CHAPTER

Number range CHAPTERTable 2. Preliminary track forecast evaluation
(heterogeneous sample) for Tropical Storm Juliette, 29 September -- 2
October 2007. 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 remnant low stage.

+-----------+-------+-------+-------+-------+-------+-------+-------+
| Number    | For   |       |       |       |       |       |       |
| range     | ecast |       |       |       |       |       |       |
| CHAPTE    | P     |       |       |       |       |       |       |
| RForecast | eriod |       |       |       |       |       |       |
| Technique | (h)   |       |       |       |       |       |       |
+===========+=======+=======+=======+=======+=======+=======+=======+
|           | 12    | 24    | 36    | 48    | 72    | 96    | 120   |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CLP5      | 48    | 92    | 156 ( | 242 ( | 391 ( |       |       |
|           | (12)  | (10)  | 8)    | 6)    | 2)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFNI      | 37 (  | 71 (  | 100 ( | 160 ( |       |       |       |
|           | 6)    | 5)    | 3)    | 1)    |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDI      | 34    | 59    | 75 (  | 107 ( | **    |       |       |
|           | (12)  | (10)  | 8)    | 6)    | 189** |       |       |
|           |       |       |       |       | **(   |       |       |
|           |       |       |       |       | 2)**  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFSI      | 40    | 68    | 92 (  | 114 ( | 258 ( |       |       |
|           | (12)  | (10)  | 8)    | 6)    | 2)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| AEMI      | 33    | 61    | 90 (  | 125 ( | **    |       |       |
|           | (12)  | (10)  | 8)    | 6)    | 123** |       |       |
|           |       |       |       |       | **(   |       |       |
|           |       |       |       |       | 2)**  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NGPI      | 48 (  | 67 (  | 71 (  | 91 (  | **    |       |       |
|           | 8)    | 6)    | 5)    | 3)    | 126** |       |       |
|           |       |       |       |       | **(   |       |       |
|           |       |       |       |       | 2)**  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| UKMI      | 46 (  | 79 (  | 92 (  | 101 ( |       |       |       |
|           | 9)    | 7)    | 5)    | 3)    |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMD      | 81    | 168   | 257 ( | 327 ( | 333 ( |       |       |
|           | (12)  | (10)  | 8)    | 6)    | 2)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMM      | 63    | 121 ( | 178 ( | 213 ( | 213 ( |       |       |
|           | (11)  | 9)    | 7)    | 5)    | 2)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMS      | 35    | 57 (  | 83 (  | 122 ( | 240 ( |       |       |
|           | (11)  | 9)    | 7)    | 5)    | 2)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CONU      | 35    | 59    | 70 (  | **79  | **    |       |       |
|           | (12)  | (10)  | 8)    | (     | 111** |       |       |
|           |       |       |       | 6)**  | **(   |       |       |
|           |       |       |       |       | 2)**  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GUNA      | 35 (  | 53 (  | 68 (  | 106 ( |       |       |       |
|           | 6)    | 4)    | 3)    | 1)    |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| FSSE      | 32 (  | 66 (  | 93 (  | 89 (  |       |       |       |
|           | 9)    | 7)    | 5)    | 3)    |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| OFCL      | 28    | 40 (  | 48 (  | 83 (  | 213 ( |       |       |
|           | (11)  | 9)    | 7)    | 5)    | 1)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NHC       | 33    | 57    | 79    | 99    | 140   | 188   | 233   |
| Official  | (     | (     | (     | (897) | (655) | (465) | (311) |
|           | 1349) | 1192) | 1039) |       |       |       |       |
| (         |       |       |       |       |       |       |       |
| 2002-2006 |       |       |       |       |       |       |       |
| mean)     |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+

Table 3. Preliminary intensity forecast evaluation (heterogeneous
sample) for Tropical Storm Juliette, 29 September -- 2 October 2007.
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 remnant low stage.

+-----------+-------+-------+-------+-------+-------+-------+-------+
| Number    | For   |       |       |       |       |       |       |
| range     | ecast |       |       |       |       |       |       |
| CHAPTE    | P     |       |       |       |       |       |       |
| RForecast | eriod |       |       |       |       |       |       |
| Technique | (h)   |       |       |       |       |       |       |
+===========+=======+=======+=======+=======+=======+=======+=======+
|           | 12    | 24    | 36    | 48    | 72    | 96    | 120   |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| SHF5      | 6.5   | 7.7   | 7.0 ( | 6.7 ( | 22.5  |       |       |
|           | (12)  | (10)  | 8)    | 6)    | ( 2)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GHMI      | 7.3   | 11.3  | 14.9  | 11.3  | **5.0 |       |       |
|           | (12)  | (10)  | ( 8)  | ( 6)  | (     |       |       |
|           |       |       |       |       | 2)**  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| SHIP      | 6.9   | 8.5   | 6.4 ( | 6.8 ( | **6.5 |       |       |
|           | (12)  | (10)  | 8)    | 6)    | (     |       |       |
|           |       |       |       |       | 2)**  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| DSHP      | 6.9   | 8.5   | 6.4 ( | 6.8 ( | **6.5 |       |       |
|           | (12)  | (10)  | 8)    | 6)    | (     |       |       |
|           |       |       |       |       | 2)**  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| FSSE      | 6.8 ( | 7.4 ( | 5.8 ( | **2.7 |       |       |       |
|           | 9)    | 7)    | 5)    | (     |       |       |       |
|           |       |       |       | 3)**  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| ICON      | 6.3   | 8.8   | 10.1  | 6.0 ( | **3.5 |       |       |
|           | (12)  | (10)  | ( 8)  | 6)    | (     |       |       |
|           |       |       |       |       | 2)**  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| OFCL      | 3.2   | 3.9 ( | 3.6 ( | 4.0 ( | 10.0  |       |       |
|           | (11)  | 9)    | 7)    | 5)    | ( 1)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NHC       | 6.3   | 11.0  | 14.6  | 16.9  | 18.9  | 18.5  | 19.3  |
| Official  | (     | (     | (     | (896) | (655) | (465) | (311) |
|           | 1349) | 1192) | 1039) |       |       |       |       |
| (         |       |       |       |       |       |       |       |
| 2002-2006 |       |       |       |       |       |       |       |
| mean)     |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+

![](media/image1.wmf){width="7.874305555555556in"
height="6.127777777777778in"}

Number range CHAPTERFigure 1. Best track positions for Tropical Storm
Juliette, 29 September -- 2 October 2007.

![](media/image2.wmf){width="7.097222222222222in"
height="4.814583333333333in"}

Number range CHAPTERFigure 2. Selected wind observations and best track
maximum sustained surface wind speed curve for Tropical Storm Juliette,
29 September -- 2 October 2007.

![](media/image3.wmf){width="7.083333333333333in"
height="4.814583333333333in"}

Number range CHAPTERFigure 3. Selected pressure observations and best
track minimum central pressure curve for Tropical Storm Juliette, 29
September -- 2 October 2007.

Number range CHAPTER