Tropical Cyclone Report

Hurricane Paul

(EP172006)

21-26 October 2006

Jamie R. Rhome and Robert J. Berg

National Hurricane Center

20 November 2006

Paul was a category two hurricane on the Saffir-Simpson scale over the
open waters of the eastern North Pacific. Paul eventually weakened to a
tropical storm as it passed south of Baja California, then made landfall
along the coast of mainland Mexico near the southern end of Isla
Altamura and later dissipated inland over mainland Mexico. Paul caused
significant rainfall and floods in the Mexican state of Sinaloa and was
responsible for four deaths in Mexico.

a.  Synoptic History

    Paul formed from a tropical wave that emerged from the west coast of
    Africa on 4 October. The wave moved westward across the Atlantic
    Ocean and Caribbean Sea during the next two weeks and produced
    little deep convection. The wave crossed Central America on 18
    October and moved into a pre-existing area of disturbed weather over
    the eastern North Pacific on 19 October, which resulted in the
    formation of a larger area of convection that extended northward to
    the southern coast of Mexico. An area of low pressure later
    developed on 20 October, and a tropical depression is estimated to
    have formed around 0600 UTC 21 October about 230 n mi
    south-southwest of Manzanillo, Mexico. The "best track" chart 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 quickly became more organized and strengthened to a
    tropical storm only six hours after genesis. Under the influence of
    increasing easterly shear associated with a middle to
    upper-tropospheric ridge over Mexico, however, only modest
    additional development occurred during the next 24 h. As Paul
    reached the western periphery of the ridge late on 22 October,
    vertical shear decreased, and the cyclone rapidly intensified
    between 1800 UTC 22 October and 1200 UTC 23 October. During this 18
    h period, maximum sustained winds increased from 45 kt to 90 kt. In
    addition, Paul's forward speed decreased as it began to turn toward
    the north. The hurricane then began to interact with a large middle
    to upper-level trough off the west coast of the United States,
    resulting in increasing westerly shear and subsequent weakening
    starting late on 23 October.

    After its center passed just west of Socorro Island early on 24
    October, Paul became embedded within an area of deep southwesterly
    flow ahead of the upper-level trough and it accelerated
    northeastward. Weakening was temporarily arrested early on 25
    October due to a burst of deep convection as the cyclone approached
    the southern tip of Baja California. However, strong vertical shear
    began to displace the convection to the northeast while the center
    was passing about 40 n mi south of Cabo San Lucas Mexico early on 25
    October. The low-level circulation became completely exposed a few
    hours later, and Paul weakened to a depression by 0000 UTC 26
    October as it approached the coast of mainland Mexico. The
    increasingly shallow cyclone turned toward the north with a decrease
    in forward speed and made landfall along the coast of mainland
    Mexico near the southern end of Isla Altamura around 0400 UTC 26
    October. Paul dissipated a few hours later approximately 50 n mi
    northwest of Culiacán near La Bahia de Santa Maria, Mexico.

b.  Meteorological Statistics

    Observations in Paul (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,
    and Defense Meteorological Satellite Program (DMSP) satellites were
    also useful in tracking Paul. Observations from aircraft include
    flight-level and dropwindsonde data from two missions flown by the
    53rd Weather Reconnaissance Squadron of the U. S. Air Force Reserve
    Command. A total of four center fixes was obtained during these
    missions.

    The estimated peak intensity of 90 kt at 1200 UTC 23 October is
    based on unanimous subjective Dvorak intensity estimates from TAFB,
    SAB, and AFWA. While subsequent subjective satellite intensity
    estimates indicated that Paul maintained this intensity for another
    12-18 h, the best track intensity during this period is set beneath
    those estimates based on the aircraft data. A flight-level wind of
    88 kt at 1745 UTC 23 October was measured in the northeastern
    quadrant. This observation corresponds to a surface wind speed
    estimate of about 79 kt using the standard 90% adjustment factor
    from 700 mb. There was a single ship report of winds of tropical
    storm force in the vicinity of Paul, although this observation was
    judged to be incorrect.

c.  Casualty and Damage Statistics

    Since Paul weakened considerably before passing south of the Baja
    California peninsula as a tropical storm, it spared land areas from
    significant damage. However, the cyclone produced large waves and
    high surf over southern portions of Baja California that resulted in
    two deaths there. One death involved an American tourist who was
    swept out to sea, while the second death occurred when a fisherman
    was swept off rocks in high surf.

    Paul weakened to a tropical depression as it approached mainland
    Mexico but still produced very heavy rainfall resulting in floods in
    the state of Sinaloa. According to media reports, five thousand
    homes were damaged in Sinaloa causing 20,000 people to be displaced.
    The worst flooding occurred in Villa Juarez where a canal overflowed
    and flooded streets with approximately three feet of water. Two
    deaths occurred in the municipality of Navolato where a truck was
    swept away by a swollen river, bringing the total death toll
    directly attributable to Paul to four.

d.  Forecast and Warning Critique

The disturbance which eventually became Paul was first mentioned in the
National Hurricane Center (NHC) eastern North Pacific Tropical Weather
Outlook (TWO) beginning at 1600 UTC 19 October. The possibility that a
tropical depression could form was first indicated in the TWO 24 h later
at 1600 UTC 20 October, approximately 14 hours prior to genesis.

A verification of official and guidance model track forecasts is given
in Table 2. Average official track errors for Paul were 38, 71, 96, 144,
201, and 231 n mi for the 12, 24, 36, 48, 72, and 96 h forecasts,
respectively. The official track errors for Paul are larger than the
average long-term track errors at all forecast times, largely owing to a
slower than expected northward turn. In addition, Paul's sudden
decoupling and weakening on 25 October resulted in an abrupt,
unanticipated deceleration. The official track forecasts were bested by
the GUNA and CONU consensus models for the 12, 24, 36, and 48 h
forecasts but were better than the consensus models for the 72 h
forecasts. Among the individual dynamical models, only the NOGAPS model
consistently performed better than the official forecast with smaller
track errors for the 24, 36, 48, and 72 h forecasts.

Average official intensity errors were 11, 17, 21, 16, 14 and 11 kt for
the 12, 24, 36, 48, 72, and 96 h forecasts, respectively. These errors
are higher than the average long-term official intensity errors of 6,
11, and 14 kt for the 12, 24, and 36 h forecasts, respectively.
Conversely, the official forecast intensity errors were lower than the
long-term average intensity errors of 17, 19, and 18 kt for the 48, 72,
and 96 h forecasts, respectively. The higher than normal forecast errors
for the shorter-term forecasts were due to the rapid intensification
that took place from 22-23 October, which once again highlights the
difficulty in forecasting rapid intensity changes. The official
intensity forecasts were better than the simple model consensus (ICON)
for the 36, 48, and 96 h forecasts. Of the individual intensity models,
none consistently beat the official forecasts.

Watches and warnings that were issued by the government of Mexico for
Paul are listed in Table 5. Both a hurricane watch and a tropical storm
warning were issued for southern portions of Baja California. A tropical
storm watch was issued along the coast of mainland Mexico from Mazatlan
to Altata approximately 43 hours prior to landfall near the southern end
of Isla Altamura. A tropical storm warning was issued for the same area
approximately 13 hours prior to landfall.

Table 1. Best track for Hurricane Paul, 21-26 October 2006.

+-----------+--------+---------+-----------+---------+----------------+
| Date/Time | La     | Lo      | Pressure  | Wind    | Stage          |
|           | titude | ngitude |           | Speed   |                |
| (UTC)     |        |         | (mb)      |         |                |
|           | \(N\)  | \(W\)   |           | (kt)    |                |
+-----------+--------+---------+-----------+---------+----------------+
| 21 / 0600 | 15.7   | 105.6   | 1004      | 30      | tropical       |
|           |        |         |           |         | depression     |
+-----------+--------+---------+-----------+---------+----------------+
| 21 / 1200 | 15.8   | 106.5   | 1002      | 35      | tropical storm |
+-----------+--------+---------+-----------+---------+----------------+
| 21 / 1800 | 15.8   | 107.4   | 1000      | 45      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 22 / 0000 | 15.8   | 108.1   | 1000      | 45      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 22 / 0600 | 15.8   | 108.8   | 1000      | 45      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 22 / 1200 | 15.8   | 109.5   | 1000      | 45      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 22 / 1800 | 15.8   | 110.2   | 994       | 55      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 23 / 0000 | 15.9   | 110.8   | 980       | 75      | hurricane      |
+-----------+--------+---------+-----------+---------+----------------+
| 23 / 0600 | 16.1   | 111.3   | 973       | 85      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 23 / 1200 | 16.3   | 111.4   | 970       | 90      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 23 / 1800 | 16.7   | 111.6   | 978       | 80      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 24 / 0000 | 17.3   | 111.8   | 979       | 75      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 24 / 0600 | 18.0   | 111.9   | 987       | 65      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 24 / 1200 | 18.8   | 111.9   | 992       | 55      | tropical storm |
+-----------+--------+---------+-----------+---------+----------------+
| 24 / 1800 | 19.8   | 111.5   | 998       | 45      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 25 / 0000 | 20.8   | 111.0   | 1000      | 40      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 25 / 0600 | 21.7   | 110.3   | 1000      | 40      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 25 / 1200 | 22.6   | 109.3   | 1001      | 40      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 25 / 1800 | 23.7   | 108.1   | 1003      | 35      | \"             |
+-----------+--------+---------+-----------+---------+----------------+
| 26 / 0000 | 24.5   | 108.1   | 1005      | 25      | tropical       |
|           |        |         |           |         | depression     |
+-----------+--------+---------+-----------+---------+----------------+
| 26 / 0600 | 25.0   | 108.1   | 1008      | 25      | remnant low    |
+-----------+--------+---------+-----------+---------+----------------+
| 26 / 1200 |        |         |           |         | dissipated     |
+-----------+--------+---------+-----------+---------+----------------+
| 23 / 1200 | 16.3   | 111.4   | 970       | 90      | minimum        |
|           |        |         |           |         | pressure       |
+-----------+--------+---------+-----------+---------+----------------+
| 26/0400   | 24.8   | 108.1   | 1007      | 25      | landfall near  |
|           |        |         |           |         | the southern   |
|           |        |         |           |         | end of Isla    |
|           |        |         |           |         | Altamura       |
+-----------+--------+---------+-----------+---------+----------------+

Table 2. Preliminary track forecast evaluation (heterogeneous sample)
for Hurricane Paul, 21-26 October 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. ^\*^Output from these models is
unavailable at forecast time

+-----------+-------+-------+-------+-------+-------+-------+-------+
| Forecast  | For   |       |       |       |       |       |       |
| Technique | ecast |       |       |       |       |       |       |
|           | P     |       |       |       |       |       |       |
|           | eriod |       |       |       |       |       |       |
|           | (h)   |       |       |       |       |       |       |
+===========+=======+=======+=======+=======+=======+=======+=======+
|           | 12    | 24    | 36    | 48    | 72    | 96    | 120   |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CLP5      | *     | 75    | 140   | 201   | 349 ( | 490 ( |       |
|           | *35** | (16)  | (14)  | (12)  | 8)    | 4)    |       |
|           | (18)  |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFNI      | 42    | 82    | 125   | 164 ( | 387 ( | 475 ( |       |
|           | (15)  | (13)  | (11)  | 9)    | 5)    | 2)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDI      | 46    | 85    | 142   | 269   | 522 ( | 480 ( |       |
|           | (18)  | (16)  | (14)  | (12)  | 7)    | 3)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDL\*    | *     | 72    | 109   | 196   | 524 ( | 561 ( |       |
|           | *35** | (16)  | (14)  | (12)  | 7)    | 2)    |       |
|           | (18)  |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDN\*    | *     | *     | 111   | 149   | 314 ( | 414 ( |       |
|           | *36** | *69** | (12)  | (10)  | 6)    | 2)    |       |
|           | (17)  | (14)  |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFSI      | 60    | 90    | 120   | 174   | 242 ( | 254 ( |       |
|           | (18)  | (14)  | (13)  | (11)  | 5)    | 1)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFSO\*    | 51    | 97    | 104   | 166 ( | **    | **    |       |
|           | (17)  | (14)  | (11)  | 9)    | 157** | 162** |       |
|           |       |       |       |       | ( 2)  | ( 1)  |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| AEMI      | 52    | 96    | 134   | 160   | **    | **    |       |
|           | (18)  | (16)  | (14)  | (12)  | 147** | 170** |       |
|           |       |       |       |       | ( 7)  | ( 2)  |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NGPI      | 39    | *     | *     | **    | **    | 432 ( |       |
|           | (16)  | *61** | *84** | 124** | 169** | 1)    |       |
|           |       | (13)  | (12)  | (10)  | ( 6)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NGPS\*    | *     | *     | *     | *     | **    |       |       |
|           | *31** | *57** | *67** | *93** | 162** |       |       |
|           | (17)  | (15)  | (13)  | (11)  | ( 7)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| UKMI      | 49    | 93    | 136   | 167   | *     | 586 ( |       |
|           | (16)  | (14)  | (12)  | (10)  | *92** | 2)    |       |
|           |       |       |       |       | ( 6)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| UKM\*     | 46 (  | 71 (  | 118 ( | 169 ( | **    | **    |       |
|           | 9)    | 8)    | 7)    | 6)    | 170** | 125** |       |
|           |       |       |       |       | ( 4)  | ( 2)  |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMD      | 62    | 130   | 215   | 328   | 639 ( | 946 ( |       |
|           | (18)  | (16)  | (14)  | (12)  | 8)    | 4)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMM      | 40    | *     | 107   | 169   | 339 ( | 549 ( |       |
|           | (18)  | *69** | (14)  | (12)  | 8)    | 4)    |       |
|           |       | (16)  |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMS      | 55    | 104   | 156   | 206   | 272 ( | 277 ( |       |
|           | (18)  | (16)  | (14)  | (12)  | 8)    | 4)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CONU      | *     | *     | *     | **    | 226 ( | 340 ( |       |
|           | *36** | *66** | *89** | 129** | 8)    | 3)    |       |
|           | (18)  | (16)  | (14)  | (12)  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GUNA      | *     | *     | *     | **    | 296 ( |       |       |
|           | *37** | *62** | *94** | 142** | 2)    |       |       |
|           | (16)  | (11)  | (11)  | ( 9)  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| FSSE      | 39    | *     | *     | 167   | 279 ( | 301 ( |       |
|           | (17)  | *64** | *93** | (11)  | 7)    | 3)    |       |
|           |       | (15)  | (13)  |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| OFCL      | 38    | 71    | 96    | 144   | 201 ( | 231 ( |       |
|           | (18)  | (16)  | (14)  | (12)  | 8)    | 4)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NHC       | 35    | 60    | 83    | 103   | 145   | 192   | 231   |
| Official  | (     | (     | (     | (877) | (652) | (465) | (313) |
|           | 1300) | 1152) | 1009) |       |       |       |       |
| (         |       |       |       |       |       |       |       |
| 2001-2005 |       |       |       |       |       |       |       |
| mean)     |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+

Table 3. Preliminary intensity forecast evaluation (heterogeneous
sample) for Hurricane Paul, 21-26 October 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. ^\*^Output from this model is unavailable
at forecast time.

+-----------+-------+-------+-------+-------+-------+-------+-------+
| Forecast  | For   |       |       |       |       |       |       |
| Technique | ecast |       |       |       |       |       |       |
|           | P     |       |       |       |       |       |       |
|           | eriod |       |       |       |       |       |       |
|           | (h)   |       |       |       |       |       |       |
+===========+=======+=======+=======+=======+=======+=======+=======+
|           | 12    | 24    | 36    | 48    | 72    | 96    | 120   |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| SHF5      | 11.9  | 17.4  | 24.9  | 27.8  | 15.4  | 12.3  |       |
|           | (18)  | (16)  | (14)  | (12)  | ( 8)  | ( 4)  |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDI      | 11.5  | 19.0  | **1   | 19.1  | 17.3  | 14.0  |       |
|           | (18)  | (16)  | 9.3** | (12)  | ( 6)  | ( 3)  |       |
|           |       |       | (14)  |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDL\*    | 11.3  | **1   | **2   | 17.0  | 14.6  | **    |       |
|           | (18)  | 4.8** | 0.6** | (12)  | ( 7)  | 8.0** |       |
|           |       | (16)  | (14)  |       |       | ( 2)  |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| SHIP      | 11.0  | **1   | 22.1  | 22.5  | 20.3  | 22.8  |       |
|           | (18)  | 6.0** | (14)  | (12)  | ( 8)  | ( 4)  |       |
|           |       | (16)  |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| DSHP      | 11.0  | **1   | 22.0  | 20.0  | **1   | 14.3  |       |
|           | (18)  | 6.0** | (14)  | (12)  | 2.9** | ( 4)  |       |
|           |       | (16)  |       |       | ( 8)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| FSSE      | 11.4  | **1   | **2   | 17.1  | 15.3  | **    |       |
|           | (17)  | 6.4** | 0.2** | (11)  | ( 7)  | 6.3** |       |
|           |       | (15)  | (13)  |       |       | ( 3)  |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| ICON      | 11.2  | 17.3  | **1   | **1   | 14.0  | **    |       |
|           | (17)  | (15)  | 9.9** | 5.4** | ( 5)  | 5.0** |       |
|           |       |       | (13)  | (11)  |       | ( 2)  |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| OFCL      | 10.8  | 16.9  | 21.1  | 15.8  | 13.8  | 11.3  |       |
|           | (18)  | (16)  | (14)  | (12)  | ( 8)  | ( 4)  |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NHC       | 6.2   | 10.8  | 14.3  | 16.5  | 18.7  | 18.3  | 19.3  |
| Official  | (     | (     | (     | (876) | (652) | (465) | (313) |
|           | 1300) | 1152) | 1009) |       |       |       |       |
| (         |       |       |       |       |       |       |       |
| 2001-2005 |       |       |       |       |       |       |       |
| mean)     |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+

Table 4. Watch and warning summary for Hurricane Paul, 21-26 October
2006.

  ----------- ------------------------------ ------------------------------
  Date/Time   Action                         Location
  (UTC)                                      

  23/0300     Hurricane Watch issued         Agua Blanca to La Paz

  24/0900     Hurricane Watch replaced with  Agua Blanca to La Paz
              Tropical Storm Warning         

  24/0900     Tropical Storm Watch issued    Mazatlan to Altata

  25/0300     Tropical Storm Watch           Mazatlan to Altata
              discontinued                   

  25/1500     Tropical Storm Warning issued  Mazatlan to Altata

  25/1500     Tropical Storm Warning         Agua Blanca to La Paz
              discontinued                   

  25/2300     Tropical Storm Warning         Mazatlan to Altata
              discontinued                   
  ----------- ------------------------------ ------------------------------

![](media/image1.wmf){width="8.195833333333333in"
height="6.000694444444444in"}

Figure 1. Best track positions for Hurricane Paul, 21-26 October 2006.

![](media/image2.wmf){width="7.152777777777778in"
height="4.819444444444445in"}

Figure 2. Selected wind observations and best track maximum sustained
surface wind speed curve for Hurricane Paul, 21-26 October 2006.
Aircraft observations have been adjusted for elevation using 90% and 80%
reduction factors for observations from 700 mb and 850 mb respectively.

![](media/image3.wmf){width="7.152777777777778in"
height="4.819444444444445in"}

Figure 3. Selected pressure observations and best track minimum central
pressure curve for Hurricane Paul, 21-26 October 2006.