Number range CHAPTERTropical Cyclone Report

Hurricane Florence

(AL062006)

3 -- 12 September 2006

Jack Beven

National Hurricane Center

21 December 2006

(corrected best track table 4 January 2007)

Florence was a category 1 hurricane (on the Saffir-Simpson Hurricane
Scale) that brought hurricane conditions to Bermuda. As an extratropical
low, it brought hurricane-force winds to portions of Newfoundland.

a.  Synoptic History

    Florence had a complex genesis tied to the interaction between two
    tropical waves. A tropical wave moved westward across the coast of
    Africa on 29 August. The wave moved slowly westward and first showed
    signs of convective organization on 31 August. On that day another
    wave moved westward from Africa at a faster forward speed than its
    predecessor. By 2 September, these two waves combined to form a
    large area of disturbed weather over the eastern tropical Atlantic.
    Convection increased in organization, and it is estimated that a
    tropical depression formed near 1800 UTC 3 September about 855 n mi
    west of the Cape Verde Islands. The "best track" chart of the
    tropical cyclone's path is given in Fig. 1, with the wind and
    pressure histories shown in Figs. 2 and 3, respectively. The best
    track positions and intensities are listed in Table 1.

    The depression initially had a large circulation with multiple
    vorticity centers rotating around the mean center, a condition which
    persisted into 8 September. This structure, combined with
    southwesterly vertical shear caused by an upper-level trough to the
    west, resulted in very slow development for the first several days
    of the cyclone's life. The depression became a tropical storm on 5
    September, and the estimated maximum sustained winds fluctuated
    between 35 and 45 kt for the next three days as Florence moved
    west-northwestward. The shear decreased on 8 September as an
    upper-level ridge developed over Florence. Late that day, the storm
    started to consolidate around a vorticity center on the western side
    of the large cyclonic envelope, which caused a westward jog followed
    by a turn toward the northwest. Florence strengthened slowly on 9
    September and at a faster pace the next day, with the storm becoming
    a hurricane early on 10 September about 340 n mi south of Bermuda.

    Florence gradually turned northward on 10-11 September. It reached
    its peak intensity of 80 kt late on 10 September, then maintained
    maximum sustained winds of 70-75 kt as the center passed about 50 n
    mi west of Bermuda on 11 September. The hurricane recurved
    northeastward into the westerlies the next day, and it maintained
    hurricane strength until it became extratropical early on 13
    September about 420 n mi south-southwest of Cape Race, Newfoundland.

    As an extratropical low, Florence maintained its large size and
    hurricane-force winds as it approached Newfoundland. The center
    passed near Cape Race late on 13 September, then moved
    east-northeastward over the open North Atlantic the next day. The
    low moved eastward on 15-16 September as the associated winds
    weakened to gale force. Florence then made a broad cyclonic
    half-loop over the Atlantic waters southwest of Iceland until 19
    September, when it was absorbed by a developing extratropical low to
    its south.

b.  Meteorological Statistics

    Observations in Florence (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 Command.
    Microwave satellite imagery from NOAA polar-orbiting satellites, the
    NASA Tropical Rainfall Measuring Mission (TRMM), the NASA Aqua, the
    NASA QuikSCAT, the Department of Defense WindSat, and Defense
    Meteorological Satellite Program (DMSP) satellites were also useful
    in tracking Florence.

    The 53^rd^ Weather Reconnaissance Squadron flew five missions into
    Florence, producing 15 center fixes. The maximum flight-level winds
    observed were 96 kt in the northeastern eyewall at 700 mb at 1724
    UTC 10 September. While this would normally support surface winds of
    85 kt, a subsequent pass through the northeastern eyewall measured
    winds of only 74 kt. This suggests the possibility the 96 kt winds
    were transient. Based on this assumption, the peak intensity of
    Florence is set at 80 kt -- a category 1 hurricane. However, it
    cannot be ruled out the system briefly had category 2 status near
    1800 UTC 10 October.

    Ship reports of winds of tropical storm force associated with
    Florence are given in Table 2, and selected surface observations
    from land stations and data buoys are given in Table 3. Ships mostly
    avoided Florence during its life as a tropical cyclone, and there
    were no reports from the inner core. The highest ship-reported wind
    was 44 kt from the **Lykes Discoverer** (call sign WGXO) at 0600 UTC
    12 September. A drifting buoy reported 45-kt winds at 0500 UTC 11
    September.

    Florence brought hurricane conditions to Bermuda on 11 September
    (Table 3). An automated station at St. David's (elevation 48 m)
    reported sustained winds of 71 kt at 1340 UTC that day with a gust
    to 97 kt. The Bermuda Maritime Operations Centre reported a wind
    gust of 100 kt at 1001 UTC. The Bermuda Airport reported a peak gust
    of 78 kt at 1555 UTC along with 1.32 in of rain.

    As an extratropical low, Florence brought hurricane-force winds to
    portions of Newfoundland. Sagona Island reported sustained winds of
    66 kt with a gust to 81 kt at 1500 UTC 13 September. The oil
    platform VEP717 located approximately 180 n mi east of Cape Race
    reported sustained winds of 73 kt (elevation unknown) at 0000 UTC 14
    September.

c.  Casualty and Damage Statistics

    Media reports indicate that Florence caused no deaths on Bermuda and
    only a few minor injuries. The hurricane caused minor wind damage
    and power outages on the island. Similar impacts were felt in
    Newfoundland when Florence passed as an extratropical low.

d.  Forecast and Warning Critique

    The disturbed weather area that became Florence was first mentioned
    in the Atlantic Tropical Weather Outlook about 21 h before genesis
    occurred. The potential for the system to become a tropical
    depression was first mentioned about 16 h before genesis

    A verification of official and guidance model track forecasts is
    given in Table 4. Average official track errors for Florence were
    40, 59, 72, 70, 61, 94, and 160 n mi for the 12, 24, 36, 48, 72, 96,
    and 120 h forecasts, respectively. The number of forecasts ranged
    from 35 at 12 h to 17 at 120 h. These errors are lower than the
    average long-term official track errors (Table 4) for the 24-h and
    longer forecast periods. The official errors were generally less
    than that those of the numerical guidance, with only the GUNA
    consensus model and the Florida State University Superensemble
    showing consistently lower errors than the official forecast.

    Average official intensity errors were 6, 9, 12, 15, 19, 21 and 22
    kt for the 12, 24, 36, 48, 72, 96, and 120 h forecasts,
    respectively. For comparison, the average long-term official
    intensity errors are 6, 10, 12, 14, 18, 20, and 22 kt, respectively.
    While these average errors are close to the long-term average, they
    were considerably higher than those for the climatology-persistence
    SHIFOR model, indicating that the forecasts had no skill. It should
    be noted that the official average errors were lower than those of
    the guidance, except for the interpolated GFDL model (GFDI),
    indicating that most of the guidance also had no skill. The official
    forecasts showed a large positive bias resulting from many forecasts
    of significantly greater intensification than what was observed.

    A hurricane watch was issued for Bermuda at 2100 UTC 8 September,
    while a tropical storm warning was issued for the island at 1500 UTC
    9 September. These were superseded by a hurricane warning issued for
    the island at 0900 UTC 10 September. After Florence made its closest
    approach, the hurricane warning was changed to a tropical storm
    warning at 2100 UTC 11 September, with all warnings for the island
    discontinued 6 h later.

    *Acknowledgements*

    Mark Guishard of the Bermuda Weather Service provided the data on
    Florence's impact on Bermuda. Chris Fogarty of the Canadian
    Hurricane Center in Dartmouth, Nova Scotia provided the data on
    Florence's impact in Canada.

Number range CHAPTERTable 1. Best track for Hurricane Florence, 3- 12
September 2006. Track during the extratropical stage is based on
analyses from the NOAA Ocean Prediction Center.

+---------+---------+--------+-----------+-----------+----------------+
| Da      | L       | Lon    | Pressure  | Wind      | Stage          |
| te/Time | atitude | gitude |           | Speed     |                |
|         |         |        | (mb)      |           |                |
| (UTC)   | (°N)    | (°W)   |           | (kt)      |                |
+---------+---------+--------+-----------+-----------+----------------+
| 03 /    | 14.1    | 39.4   | 1007      | 30        | tropical       |
| 1800    |         |        |           |           | depression     |
+---------+---------+--------+-----------+-----------+----------------+
| 04 /    | 14.7    | 40.0   | 1007      | 30        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 04 /    | 15.4    | 41.0   | 1007      | 30        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 04 /    | 16.0    | 42.3   | 1007      | 30        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 04 /    | 16.4    | 43.5   | 1007      | 30        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 05 /    | 16.6    | 44.8   | 1007      | 30        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 05 /    | 16.8    | 46.1   | 1007      | 35        | tropical storm |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 05 /    | 17.0    | 46.9   | 1005      | 35        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 05 /    | 17.3    | 47.8   | 1003      | 40        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 06 /    | 17.6    | 48.6   | 1003      | 40        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 06 /    | 18.1    | 49.7   | 1003      | 40        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 06 /    | 18.5    | 50.6   | 1003      | 45        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 06 /    | 19.0    | 51.3   | 1000      | 45        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 07 /    | 19.3    | 51.9   | 1000      | 45        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 07 /    | 19.6    | 52.6   | 1000      | 45        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 07 /    | 19.9    | 53.3   | 1002      | 40        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 07 /    | 20.3    | 54.3   | 1002      | 40        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 08 /    | 20.9    | 55.7   | 1002      | 40        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 08 /    | 21.5    | 57.1   | 1002      | 40        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 08 /    | 21.7    | 58.8   | 1002      | 40        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 08 /    | 21.9    | 60.1   | 1000      | 45        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 09 /    | 22.7    | 61.0   | 997       | 50        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 09 /    | 23.8    | 62.3   | 993       | 50        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 09 /    | 24.4    | 63.2   | 992       | 50        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 09 /    | 25.1    | 64.0   | 991       | 50        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 10 /    | 26.2    | 64.6   | 987       | 60        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 10 /    | 27.1    | 65.3   | 980       | 70        | hurricane      |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 10 /    | 28.1    | 65.9   | 978       | 75        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 10 /    | 29.3    | 66.1   | 976       | 80        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 11 /    | 30.4    | 66.2   | 975       | 80        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 11 /    | 31.3    | 66.2   | 977       | 70        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 11 /    | 32.4    | 65.7   | 974       | 75        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 11 /    | 33.6    | 65.0   | 974       | 75        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 12 /    | 34.9    | 64.1   | 975       | 70        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 12 /    | 36.3    | 63.2   | 976       | 65        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 12 /    | 37.4    | 61.9   | 976       | 65        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 12 /    | 38.5    | 60.2   | 977       | 65        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 13 /    | 40.6    | 57.9   | 978       | 70        | extratropical  |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 13 /    | 43.1    | 56.3   | 972       | 70        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 13 /    | 45.5    | 55.6   | 967       | 70        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 13 /    | 46.4    | 54.0   | 963       | 70        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 14 /    | 47.6    | 51.3   | 965       | 65        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 14 /    | 48.6    | 48.3   | 967       | 60        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 14 /    | 49.2    | 45.2   | 970       | 55        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 14 /    | 49.8    | 42.6   | 976       | 50        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 15 /    | 50.0    | 39.6   | 981       | 45        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 15 /    | 49.7    | 35.8   | 982       | 45        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 15 /    | 49.5    | 31.7   | 984       | 45        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 15 /    | 49.8    | 27.5   | 986       | 40        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 16 /    | 50.6    | 23.9   | 987       | 40        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 16 /    | 52.5    | 21.0   | 987       | 40        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 16 /    | 54.6    | 20.5   | 985       | 40        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 16 /    | 56.6    | 20.5   | 983       | 40        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 17 /    | 58.2    | 20.5   | 980       | 40        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 17 /    | 59.6    | 20.6   | 980       | 40        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 17 /    | 60.9    | 21.2   | 979       | 40        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 17 /    | 62.0    | 22.5   | 978       | 45        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 18 /    | 62.6    | 24.5   | 976       | 50        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 18 /    | 63.0    | 26.5   | 977       | 50        | \"             |
| 0600    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 18 /    | 63.0    | 29.0   | 978       | 50        | \"             |
| 1200    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 18 /    | 63.0    | 31.4   | 979       | 50        | \"             |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 19 /    | 62.0    | 34.0   | 982       | 50        | \"             |
| 0000    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+
| 19 /    |         |        |           |           | absorbed by    |
| 0600    |         |        |           |           | extratropical  |
|         |         |        |           |           | low            |
+---------+---------+--------+-----------+-----------+----------------+
| 11 /    | 32.4    | 65.7   | 974       | 75        | minimum        |
| 1200    |         |        |           |           | pressure       |
+---------+---------+--------+-----------+-----------+----------------+
| 10 /    | 29.3    | 66.1   | 976       | 80        | maximum wind   |
| 1800    |         |        |           |           |                |
+---------+---------+--------+-----------+-----------+----------------+

Number range CHAPTERTable 2. Selected ship and drifting buoy reports
with winds of at least 34 kt for Hurricane Florence, 3 -- 12 September
2006.

+-----------+-------------+---------+---------+-----------+-----------+
| Date/Time | Ship        | L       | Lo      | Wind      | Pressure  |
| (UTC)     | name/call   | atitude | ngitude |           |           |
|           | sign        |         |         | dir/speed | (mb)      |
|           |             | (°N)    | (°W)    | (kt)      |           |
+-----------+-------------+---------+---------+-----------+-----------+
| 08 / 0000 | **Marlene   | 23.6    | 49.3    | 090 / 39  | 1015.4    |
|           | Green**     |         |         |           |           |
+-----------+-------------+---------+---------+-----------+-----------+
| 08 / 1500 | Drifting    | 18.3    | 55.8    | 230 / 39  | 1012.0    |
|           | buoy 41657  |         |         |           |           |
+-----------+-------------+---------+---------+-----------+-----------+
| 11 / 0500 | Drifting    | 25.8    | 68.6    | 260 / 45  | 1009.8    |
|           | buoy 41646  |         |         |           |           |
+-----------+-------------+---------+---------+-----------+-----------+
| 12 / 0600 | **Lykes     | 41.3    | 65.8    | 050 / 44  | 1017.0    |
|           | D           |         |         |           |           |
|           | iscoverer** |         |         |           |           |
+-----------+-------------+---------+---------+-----------+-----------+

Number range CHAPTERTable 3. Selected surface observations for Hurricane
Florence, 3 -- 12 September 2006.

+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Location        | M   |     | M   |       |     | St  | St  | To  |
|                 | ini |     | axi |       |     | orm | orm | tal |
|                 | mum |     | mum |       |     | su  |     |     |
|                 | Sea |     | S   |       |     | rge | t   | r   |
|                 | Le  |     | urf |       |     |     | ide | ain |
|                 | vel |     | ace |       |     | (   |     |     |
|                 | Pr  |     |     |       |     | ft) | (   | (   |
|                 | ess |     | W   |       |     | ^c^ | ft) | in) |
|                 | ure |     | ind |       |     |     | ^d^ |     |
|                 |     |     | Sp  |       |     |     |     |     |
|                 |     |     | eed |       |     |     |     |     |
+=================+=====+=====+=====+=======+=====+=====+=====+=====+
|                 | Da  | Pre | Da  | Sust  | G   |     |     |     |
|                 | te/ | ss. | te/ | ained | ust |     |     |     |
|                 |     |     |     |       |     |     |     |     |
|                 | t   | (   | t   | (k    | (   |     |     |     |
|                 | ime | mb) | ime | t)^b^ | kt) |     |     |     |
|                 |     |     |     |       |     |     |     |     |
|                 | (U  |     | (U  |       |     |     |     |     |
|                 | TC) |     | TC) |       |     |     |     |     |
|                 |     |     | ^a^ |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| **Bermuda**     |     |     |     |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Bermuda Airport | N/A | 98  | 1   | 57    | 78  |     |     | 1   |
| (TXKF; Elev. 12 |     | 5.3 | 1/1 |       |     |     |     | .32 |
| m AMSL)         |     |     | 602 |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Commisioner's   |     |     | 1   | 67    | 95  |     |     |     |
| Point (Elev. 30 |     |     | 1/1 |       |     |     |     |     |
| m AMSL)         |     |     | 400 |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Esso Pier       | 1   | 98  | 1   | 38    | 61  |     |     |     |
|                 | 1/1 | 3.8 | 1/2 |       |     |     |     |     |
|                 | 500 |     | 000 |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Fort Prospect   |     |     | 1   | 49    | 82  |     |     |     |
| (Elev. 70 m     |     |     | 1/1 |       |     |     |     |     |
| AMSL)           |     |     | 340 |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Maritime        | N/A | 98  | 1   |       | 100 |     |     |     |
| Operations      |     | 0.8 | 1/1 |       |     |     |     |     |
| Centre (Elev.   |     |     | 001 |       |     |     |     |     |
| 78 m AMSL)      |     |     |     |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| St. David's     |     |     | 1   | 71    | 97  |     |     |     |
| (Elev. 48 m     |     |     | 1/1 |       |     |     |     |     |
| AMSL)           |     |     | 340 |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+

^a^ Date/time is for sustained wind when both sustained and gust are
listed.

^b^ Except as noted, sustained wind averaging periods for C-MAN and
land-based ASOS reports are 2 min; buoy averaging periods are 8 min.

^c^ Storm surge is water height above normal astronomical tide level.

^d^ Storm tide is water height above National Geodetic Vertical Datum
(1929 mean sea level).

Number range CHAPTERTable 4. Preliminary track forecast evaluation
(heterogeneous sample) for Hurricane Florence, 3 -- 12 September 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, but does not
include the extratropical stage.

+-----------+-------+-------+-------+-------+-------+-------+-------+
| Number    | For   |       |       |       |       |       |       |
| range     | ecast |       |       |       |       |       |       |
| CHAPTE    | P     |       |       |       |       |       |       |
| RForecast | eriod |       |       |       |       |       |       |
| Technique | (h)   |       |       |       |       |       |       |
+===========+=======+=======+=======+=======+=======+=======+=======+
|           | 12    | 24    | 36    | 48    | 72    | 96    | 120   |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CLP5      | 46    | 76    | 111   | 151   | 228   | 305   | 395   |
|           | (35)  | (33)  | (31)  | (29)  | (25)  | (21)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDI      | 46    | 75    | 93    | 102   | 115   | 104   | **    |
|           | (34)  | (32)  | (30)  | (28)  | (24)  | (20)  | 143** |
|           |       |       |       |       |       |       | (16)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFNI      | 45    | 71    | 88    | 108   | 148   | 218   | 283   |
|           | (31)  | (28)  | (26)  | (23)  | (19)  | (15)  | (11)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFSI      | 41    | 66    | 82    | 90    | 110   | 143   | 186   |
|           | (34)  | (32)  | (30)  | (28)  | (24)  | (20)  | (15)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| AEMI      | *     | 63    | 83    | 89    | 105   | 113   | **    |
|           | *39** | (33)  | (31)  | (29)  | (25)  | (21)  | 130** |
|           | (35)  |       |       |       |       |       | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NGPI      | 48    | 74    | 99    | 123   | 182   | 233   | 274   |
|           | (32)  | (29)  | (27)  | (25)  | (21)  | (17)  | (13)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| UKMI      | 50    | 78    | 98    | 117   | 203   | 298   | 274   |
|           | (33)  | (31)  | (29)  | (27)  | (23)  | (19)  | (15)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| A98E      | 44    | 71    | 101   | 124   | 168   | 199   | 303   |
|           | (33)  | (31)  | (29)  | (27)  | (23)  | (20)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| A9UK      | 47    | 71    | 104   | 140   | 191   |       |       |
|           | (15)  | (14)  | (13)  | (12)  | (10)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMD      | 55    | 94    | 129   | 148   | 162   | 169   | 189   |
|           | (35)  | (33)  | (31)  | (29)  | (25)  | (21)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMM      | 53    | 85    | 115   | 131   | 139   | 136   | 245   |
|           | (35)  | (33)  | (31)  | (29)  | (25)  | (21)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMS      | 60    | 96    | 123   | 140   | 184   | 188   | 253   |
|           | (35)  | (33)  | (31)  | (29)  | (25)  | (21)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| LBAR      | 46    | 79    | 110   | 132   | 184   | 204   | 265   |
|           | (35)  | (33)  | (31)  | (29)  | (25)  | (21)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CONU      | 40    | 61    | 75    | 82    | 93    | 115   | **    |
|           | (34)  | (32)  | (30)  | (28)  | (24)  | (20)  | 136** |
|           |       |       |       |       |       |       | (16)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GUNA      | *     | *     | *     | 72    | 85    | *     | *     |
|           | *39** | *56** | *69** | (25)  | (21)  | *87** | *95** |
|           | (31)  | (29)  | (27)  |       |       | (17)  | (12)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| FSSE      | *     | *     | *     | *     | 95    | 99    | **    |
|           | *34** | *48** | *61** | *69** | (18)  | (14)  | 134** |
|           | (28)  | (26)  | (24)  | (22)  |       |       | (10)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| OFCL      | 40    | 59    | 72    | 70    | 61    | 94    | 160   |
|           | (35)  | (33)  | (31)  | (29)  | (25)  | (21)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NHC       | 37    | 65    | 91    | 118   | 171   | 231   | 303   |
| Official  | (     | (     | (     | (     | (     | (913) | (742) |
|           | 1930) | 1743) | 1569) | 1410) | 1138) |       |       |
| (         |       |       |       |       |       |       |       |
| 2001-2005 |       |       |       |       |       |       |       |
| mean)     |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+

Table 5. Preliminary intensity forecast evaluation (heterogeneous
sample) for Hurricane Florence, 3 -- 12 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, but does not include the extratropical
stage.

+-----------+-------+-------+-------+-------+-------+-------+-------+
| Number    | For   |       |       |       |       |       |       |
| range     | ecast |       |       |       |       |       |       |
| CHAPTE    | P     |       |       |       |       |       |       |
| RForecast | eriod |       |       |       |       |       |       |
| Technique | (h)   |       |       |       |       |       |       |
+===========+=======+=======+=======+=======+=======+=======+=======+
|           | 12    | 24    | 36    | 48    | 72    | 96    | 120   |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| SHF5      | **    | **    | **    | **    | **1   | **1   | **    |
|           | 5.9** | 6.6** | 8.4** | 9.5** | 0.5** | 0.3** | 6.5** |
|           | (35)  | (33)  | (31)  | (29)  | (25)  | (21)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDI      | 7.5   | **    | **1   | **1   | **1   | **1   | 23.8  |
|           | (34)  | 8.2** | 0.2** | 2.7** | 7.2** | 9.8** | (16)  |
|           |       | (32)  | (30)  | (28)  | (24)  | (20)  |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| SHIP      | 6.8   | 10.8  | 14.7  | 18.8  | 24.5  | 25.4  | 23.4  |
|           | (34)  | (33)  | (31)  | (29)  | (25)  | (21)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| DSHP      | 6.8   | 10.8  | 14.7  | 18.8  | 24.5  | 25.4  | 23.4  |
|           | (34)  | (33)  | (31)  | (29)  | (25)  | (21)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| FSSE      | 7.9   | 12.0  | 16.6  | 22.5  | 30.4  | 35.1  | 32.5  |
|           | (28)  | (26)  | (24)  | (22)  | (18)  | (14)  | (10)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| ICON      | 7.0   | 9.5   | 12.8  | 16.9  | 22.0  | 24.6  | 25.4  |
|           | (33)  | (32)  | (30)  | (28)  | (24)  | (20)  | (16)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| OFCL      | 6.1   | 9.2   | 12.4  | 15.3  | 19.4  | 21.4  | 21.8  |
|           | (35)  | (33)  | (31)  | (29)  | (25)  | (21)  | (17)  |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NHC       | 6.3   | 9.8   | 12.1  | 14.3  | 18.4  | 19.8  | 21.8  |
| Official  | (     | (     | (     | (     | (     | (913) | (742) |
|           | 1930) | 1743) | 1569) | 1410) | 1138) |       |       |
| (         |       |       |       |       |       |       |       |
| 2001-2005 |       |       |       |       |       |       |       |
| mean)     |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+

Number range CHAPTER

![](media/image1.wmf){width="7.9in" height="6.04375in"}

Number range CHAPTERFigure 1. Best track positions for Hurricane
Florence, 3- 12 September 2006. Track during the extratropical stage is
based on analyses from the NOAA Ocean Prediction Center.

![](media/image2.wmf){width="7.636805555555555in"
height="5.305555555555555in"}

Number range CHAPTERFigure 2. Selected wind observations and best track
maximum sustained surface wind speed curve for Hurricane Florence, 3 --
12 September 2006. Aircraft observations have been adjusted for
elevation using 90%, 80%, and 80% reduction factors for observations
from 700 mb, 850 mb, and 1500 ft, respectively. Dropwindsonde
observations include actual 10 m winds (sfc), as well as surface
estimates derived from the mean wind over the lowest 150 m of the wind
sounding (LLM), and from the sounding boundary layer mean (MBL).
Estimates during the extratropical stage are based on analyses from the
NOAA Ocean Prediction Center.

![](media/image3.wmf){width="8.48263888888889in"
height="5.908333333333333in"}

Number range CHAPTERFigure 3. Selected pressure observations and best
track minimum central pressure curve for Hurricane Florence, 3 -- 12
September 2006. Estimates during the extratropical stage are based on
analyses from the NOAA Ocean Prediction Center.