Tropical Cyclone Report

Hurricane Beta

26-31 October 2005

Richard J. Pasch and David P. Roberts

National Hurricane Center

28 March 2006

After pounding the island of Providencia, Beta struck a sparsely-settled
area of Nicaragua with maximum sustained winds near 90 kt.

a.  Synoptic History

    Animation of infrared and visible geostationary satellite images
    indicates that the same tropical wave that produced Tropical Storm
    Alpha also generated Beta. This wave entered the Caribbean Sea on 21
    October and spawned Alpha over the northeastern Caribbean the
    following day. The wave continued westward for a few days and by 25
    October deep convection became somewhat consolidated over the
    extreme southwestern Caribbean Sea. On 26 October, curved banding
    features developed, and the system was sufficiently well-organized
    by 1800 UTC that day to designate the formation of a tropical
    depression, centered about 90 n mi north of the northern central
    coast of Panama.

    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. Initially the motion was northwestward, but in response to
    a mid-tropospheric shortwave trough over the southern Gulf of Mexico
    and a mid-tropospheric ridge well to the east-northeast, the system
    gradually turned toward the north. Within an environment of weak
    vertical wind shear and sea-surface temperatures of at least 29C,
    the cyclone strengthened into a tropical storm around 0600 UTC 27
    October. There was only slow strengthening over the ensuing 36 h or
    so, probably due to a slight disruption of the system by weak to
    moderate northeasterly shear. By 0000 UTC 29 October the shear
    apparently diminished, and Beta intensified into a hurricane shortly
    thereafter, while passing near Isla de Providencia. As the Gulf of
    Mexico shortwave trough lifted northeastward and a mid-tropospheric
    high built to the north and northwest of the hurricane, Beta turned
    toward the west and west-southwest and continued to strengthen. Also
    around 0000 UTC 30 October, the cloud pattern became substantially
    better organized, and the hurricane strengthened more rapidly. A
    peak intensity of 100 kt was reached around 0600 UTC 30 October,
    which resulted in the seventh, and last, major hurricane of the 2005
    Atlantic season. Moving southwestward, the center of the hurricane
    made landfall near La Barra del Rio Grande on the central coast of
    Nicaragua around 1200 UTC 30 October. Shortly before the eye reached
    the coast, the central cloud tops warmed, and the hurricane's
    intensity at landfall is estimated to have been 90 kt, or category 2
    strength on the Saffir-Simpson Hurricane scale. Beta turned back
    toward the west and dissipated over west-central Nicaragua by 0600
    UTC 31 October.

b.  Meteorological Statistics

    Observations in Beta (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), as well as flight-level
    and dropwindsonde observations from flights of the 53^rd^ Weather
    Reconnaissance Squadron of the U. S. Air Force Reserve (AFRES)
    Command. 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 Beta. The highest (700 mb)
    flight-level winds measured by the AFRES were 77 kt at 2003 UTC 29
    October. However, just after the aircraft left the area, microwave
    imagery showed that the eye contracted, and Dvorak estimates
    indicate that Beta strengthened rather rapidly from 0000 to 0600 UTC
    30 October. The 100-kt peak intensity estimate is based on a
    consensus T-number of 5.5 from TAFB, SAB, and AFWA. Beta's landfall
    intensity of 90 kt is based on a Dvorak data T-number of 5.0 from
    TAFB.

    Aircraft flight-level wind data and satellite images indicate that
    Beta was a small tropical cyclone; the radius of tropical storm
    force winds was generally 50 n mi or less.

    Rainfall totals as high as 10 to 20 inches were observed over
    portions of Honduras, with a maximum total of 21.82 inches at
    Trujillo. However, it is not certain whether all of these rains were
    directly associated with Beta. There are no meteorological reports
    available near the point of landfall in Nicaragua. Puerto Cabezas,
    Nicaragua had a storm total rainfall of 6.39 inches with 5.16 inches
    falling in a 6-h period on 29 October.

    There were two ship reports of winds of tropical storm force
    associated with Beta, and these are given in Table 2.

c.  Casualty and Damage Statistics

    Beta reportedly caused extensive damage on the Colombian island of
    Providencia, however details of these impacts are unknown. According
    to information from the government of Nicaragua, roofs were removed
    from numerous dwellings and there was moderate storm surge flooding
    near the landfall location in Nicaragua. Major flooding occurred in
    Honduras, but it cannot be determined whether all of this flooding
    was directly associated with Beta. There are no reported deaths due
    to Beta.

d.  Forecast and Warning Critique

    The area of disturbed weather that developed into Beta was first
    mentioned in the National Hurricane Center's Tropical Weather
    Outlook (TWO) a little over 24 h prior to genesis. Only slow
    development of the system was anticipated, however. The TWO that was
    issued a few hours prior to Beta's genesis did indicate that a
    tropical depression could form.

    Average official track errors (with the number of cases in
    parentheses) for Beta were 27 (15), 55 (13), 74 (11), 90 (9), and
    88 (5) n mi for the 12, 24, 36, 48, and 72 h forecasts, respectively
    (there were no official forecasts verifying at 96 or 120 h). These
    errors are lower than the average official track errors for the
    10-yr period 1995-2004 of 42, 75, 107, 138, and 202 n mi,
    respectively. Even though the mean official track errors were lower
    than average, there was an overall west-northwest bias in the
    official forecasts. This resulted in landfall predictions that were
    too soon and too far north in Nicaragua. It should be noted that the
    GFDL model generally did a better job of specifying the location of
    landfall in Nicaragua than the official forecasts. Table 3 lists the
    mean errors for the various numerical track guidance models or model
    combinations in comparison to those for the official forecasts (this
    is a heterogeneous comparison). The consensus models CONU and GUNA
    had lower average track forecast errors than the official forecasts
    at 12 through 72 h, and the Florida State University Superensemble
    (FSSE) had lower mean track errors than the official forecasts at 24
    through 72 h.

    Average official intensity errors were 10, 14, 11, 11, and 41 kt for
    the 12, 24, 36, 48, and 72 h forecasts, respectively. For
    comparison, the average official intensity errors over the 10-yr
    period 1995-2004 are 6, 10, 12, 15, and 18 kt, respectively, so the
    mean official intensity forecast was substantially worse than
    average at 72 h (albeit for only 5 cases).

Table 4 is a listing of the watches and warnings that were issued for
Beta. Hurricane warnings were issued for Providencia about 33 h before
the closest approach of the center to that island. A hurricane warning
was issued for the coast of Nicaragua 39 h prior to landfall of the
center.

Table 1. Best track for Hurricane Beta, 26-31 October 2005.

+-----------+---------+---------+---------+---------+----------------+
| Date/Time | L       | Lo      | P       | Wind    | Stage          |
|           | atitude | ngitude | ressure | Speed   |                |
| (UTC)     |         |         |         |         |                |
|           | \(N\)   | \(W\)   | (mb)    | (kt)    |                |
+-----------+---------+---------+---------+---------+----------------+
| 26 / 1800 | 10.4    | 80.9    | 1007    | 30      | tropical       |
|           |         |         |         |         | depression     |
+-----------+---------+---------+---------+---------+----------------+
| 27 / 0000 | 10.7    | 81.1    | 1007    | 30      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 27 / 0600 | 11.0    | 81.3    | 1005    | 35      | tropical storm |
+-----------+---------+---------+---------+---------+----------------+
| 27 / 1200 | 11.3    | 81.3    | 1000    | 45      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 27 / 1800 | 11.6    | 81.3    | 997     | 50      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 28 / 0000 | 11.9    | 81.2    | 995     | 50      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 28 / 0600 | 12.3    | 81.1    | 994     | 50      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 28 / 1200 | 12.8    | 81.0    | 993     | 50      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 28 / 1800 | 13.2    | 81.1    | 991     | 50      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 29 / 0000 | 13.4    | 81.2    | 988     | 60      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 29 / 0600 | 13.6    | 81.4    | 985     | 70      | hurricane      |
+-----------+---------+---------+---------+---------+----------------+
| 29 / 1200 | 13.7    | 81.6    | 982     | 75      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 29 / 1800 | 13.7    | 82.1    | 980     | 75      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 0000 | 13.6    | 82.6    | 970     | 90      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 0600 | 13.3    | 83.1    | 962     | 100     | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 1200 | 12.9    | 83.5    | 970     | 90      | \"             |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 1800 | 12.7    | 84.1    | 990     | 55      | tropical storm |
+-----------+---------+---------+---------+---------+----------------+
| 31 / 0000 | 12.7    | 84.9    | 1000    | 20      | tropical       |
|           |         |         |         |         | depression     |
+-----------+---------+---------+---------+---------+----------------+
| 31 / 0600 |         |         |         |         | dissipated     |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 0600 | 13.3    | 83.1    | 962     | 100     | minimum        |
|           |         |         |         |         | pressure       |
+-----------+---------+---------+---------+---------+----------------+
| 30 / 1200 | 12.9    | 83.5    | 970     | 90      | landfall near  |
|           |         |         |         |         | La Barra del   |
|           |         |         |         |         | Rio Grande,    |
|           |         |         |         |         | Nicaragua      |
+-----------+---------+---------+---------+---------+----------------+

Table 2. Selected ship reports with winds of at least 34 kt for
Hurricane Beta, 26-31 October 2005.

+-----------+-----------+-----------+-----------+-----------+-----------+
| Date/Time | Ship call | Latitude  | Longitude | Wind      | Pressure  |
| (UTC)     | sign      |           |           |           |           |
|           |           | \(N\)     | \(W\)     | dir/speed | (mb)      |
|           |           |           |           | (kt)      |           |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 28 / 0900 | ZCAM4     | 12.3      | 80.9      | 270 / 50  | 999.7     |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 30 / 0600 | PJRP      | 18.6      | 83.6      | 060 / 39  | 1013.7    |
+-----------+-----------+-----------+-----------+-----------+-----------+

Table 3. Preliminary forecast evaluation (heterogeneous sample) for
Hurricane Beta, 26-31 October 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.

+-----------+-------+-------+-------+-------+-------+-------+-------+
| Forecast  | For   |       |       |       |       |       |       |
| Technique | ecast |       |       |       |       |       |       |
|           | P     |       |       |       |       |       |       |
|           | eriod |       |       |       |       |       |       |
|           | (h)   |       |       |       |       |       |       |
+===========+=======+=======+=======+=======+=======+=======+=======+
|           | 12    | 24    | 36    | 48    | 72    | 96    | 120   |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CLP5      | 42    | 90    | 138   | 176   | 237 ( | 266 ( |       |
|           | (16)  | (14)  | (12)  | (10)  | 6)    | 2)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFNI      | 29    | *     | *     | *     | 91 (  | 67 (  |       |
|           | (16)  | *46** | *52** | *58** | 5)    | 2)    |       |
|           |       | (14)  | (12)  | ( 9)  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDI      | 32    | *     | 77    | 112 ( | 194 ( | 280 ( |       |
|           | (16)  | *50** | (11)  | 9)    | 5)    | 1)    |       |
|           |       | (13)  |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFSI      | *     | *     | *     | *     | 132 ( |       |       |
|           | *23** | *38** | *56** | *62** | 3)    |       |       |
|           | (13)  | (11)  | ( 9)  | ( 7)  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| AEMI      | *     | *     | *     | *     | 109 ( |       |       |
|           | *26** | *39** | *51** | *54** | 3)    |       |       |
|           | (13)  | (11)  | ( 9)  | ( 7)  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NGPI      | 36    | 59    | *     | *     | *     | 27 (  |       |
|           | (16)  | (14)  | *72** | *72** | *62** | 2)    |       |
|           |       |       | (12)  | (10)  | ( 6)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| UKMI      | 33    | 69    | 89 (  | 120 ( | 218 ( |       |       |
|           | (12)  | (10)  | 8)    | 6)    | 2)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| A98E      | 39    | 91    | 152   | 214   | 371 ( | 656 ( |       |
|           | (16)  | (14)  | (12)  | (10)  | 6)    | 2)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| A9UK      | 41 (  | 91 (  | 150 ( | 200 ( | 306 ( |       |       |
|           | 8)    | 7)    | 6)    | 5)    | 3)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMD      | 59    | 108   | 162   | 207   | 336 ( | 462 ( |       |
|           | (16)  | (14)  | (12)  | (10)  | 6)    | 2)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMM      | 45    | 85    | 133   | 174 ( | 296 ( | 469 ( |       |
|           | (15)  | (13)  | (11)  | 9)    | 6)    | 2)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMS      | 45    | 85    | 125   | 158   | 264 ( | 419 ( |       |
|           | (16)  | (14)  | (12)  | (10)  | 6)    | 2)    |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CONU      | *     | *     | *     | *     | *     | 73 (  |       |
|           | *25** | *40** | *56** | *65** | *73** | 2)    |       |
|           | (16)  | (14)  | (12)  | (10)  | ( 6)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GUNA      | *     | *     | *     | *     | *     |       |       |
|           | *23** | *38** | *53** | *62** | *78** |       |       |
|           | (12)  | (10)  | ( 8)  | ( 6)  | ( 2)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| FSSE      | 28    | *     | *     | *     | *     |       |       |
|           | (13)  | *46** | *55** | *62** | *65** |       |       |
|           |       | (11)  | ( 9)  | ( 7)  | ( 3)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| OFCL      | 27    | 55    | 74    | 90 (  | 88 (  |       |       |
|           | (15)  | (13)  | (11)  | 9)    | 5)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NHC       | 42    | 75    | 107   | 138   | 202   | 236   | 310   |
| Official  | (     | (     | (     | (     | (     | (649) | (535) |
|           | 3400) | 3116) | 2848) | 2575) | 2117) |       |       |
| (         |       |       |       |       |       |       |       |
| 1995-2004 |       |       |       |       |       |       |       |
| mean)     |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+

Table 4. Watch and warning summary for Hurricane Beta, 26-31 October
2005.

+----------+-----------------------------+-----------------------------+
| D        | Action                      | Location                    |
| ate/Time |                             |                             |
| (UTC)    |                             |                             |
+----------+-----------------------------+-----------------------------+
| 27/0300  | Tropical Storm Warning      | Nicaragua/Costa Rica border |
|          |                             |                             |
|          | issued                      | To Cabo Gracias a Dios      |
|          |                             |                             |
|          |                             | and adjacent islands        |
+----------+-----------------------------+-----------------------------+
| 27/0600  | Tropical Storm Warning      | San Andres and Providencia  |
|          |                             |                             |
|          | issued                      | islands                     |
+----------+-----------------------------+-----------------------------+
| 27/0900  | Hurricane Watch             | San Andres and Providencia  |
|          |                             |                             |
|          | issued                      | Islands                     |
+----------+-----------------------------+-----------------------------+
| 27/1500  | Hurricane Warning           | San Andres and Providencia  |
|          |                             |                             |
|          | issued                      | Islands                     |
+----------+-----------------------------+-----------------------------+
| 27/1500  | Hurricane Watch             | Nicaragua/Costa Rica border |
|          |                             |                             |
|          | issued                      | To Cabo Gracias a Dios      |
|          |                             |                             |
|          |                             | and adjacent islands        |
+----------+-----------------------------+-----------------------------+
| 28/1500  | Tropical Storm Watch        | Limon to Cabo Gracia A Dios |
|          |                             |                             |
|          | issued                      |                             |
+----------+-----------------------------+-----------------------------+
| 28/2100  | Hurricane Warning           | Bluefields to Cabo Gracias  |
|          |                             | A dios                      |
|          | issued                      |                             |
|          |                             | And adjacent islands        |
+----------+-----------------------------+-----------------------------+
| 28/2100  | Tropical Storm Warning and  | Bluefields to the Costa     |
|          |                             | Rica border                 |
|          | Hurricane Watch modified to |                             |
+----------+-----------------------------+-----------------------------+
| 29/0300  | Hurricane Watch             | Punta Patuca to Cabo        |
|          |                             | Gracias A Dios              |
|          | issued                      |                             |
+----------+-----------------------------+-----------------------------+
| 29/0300  | Tropical Storm Watch        | Limon to Punta Patuca       |
|          | modified                    |                             |
|          |                             | Including La Ceiba          |
|          | to                          |                             |
+----------+-----------------------------+-----------------------------+
| 29/1500  | Hurricane Watch changed     | Punta Patuca to Cabo        |
|          |                             | Gracias A Dios              |
|          | To Hurricane Warning        |                             |
+----------+-----------------------------+-----------------------------+
| 30/0000  | Hurricane Warning           | San Andres and Providencia  |
|          |                             |                             |
|          | discontinued                | Islands                     |
+----------+-----------------------------+-----------------------------+
| 30/1500  | Hurricane Warning           | Punta Patuca to Cabo        |
|          |                             | Gracias A Dios              |
|          | discontinued                |                             |
+----------+-----------------------------+-----------------------------+
| 30/1500  | Tropical Storm Watch        | Limon to Punta Patuca       |
|          |                             |                             |
|          | discontinued                | Including La Ceiba          |
+----------+-----------------------------+-----------------------------+
| 04/1800  | Hurricane Watch             | Bluefields to the Costa     |
|          |                             | Rica border                 |
|          | discontinued                |                             |
+----------+-----------------------------+-----------------------------+
| 30/2100  | Hurricane Warning           | Bluefields to Cabo Gracias  |
|          |                             | A dios                      |
|          | discontinued                |                             |
|          |                             | And adjacent islands        |
+----------+-----------------------------+-----------------------------+
| 30/2100  | Tropical Storm Warning      | Bluefields to Costa Rica    |
|          |                             | border                      |
|          | discontinued                |                             |
+----------+-----------------------------+-----------------------------+
| 30/2100  | Tropical Storm Warning      | Bluefields to Puerto        |
|          |                             | Cabezas                     |
|          | issued                      |                             |
+----------+-----------------------------+-----------------------------+
| 31/0000  | Tropical Storm Warning      | Bluefields to Puerto        |
|          |                             | Cabezas                     |
|          | discontinued                |                             |
+----------+-----------------------------+-----------------------------+

![](media/image1.wmf){width="7.820138888888889in"
height="6.002083333333333in"}

Figure 1. Best track positions for Hurricane Beta, 26-31 October 2005.

![](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 Beta, 26-31 October 2005.
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 Beta, 26-31 October 2005.