Tropical Cyclone Report

Tropical Storm Chris

(AL032006)

1-4 August 2006

Stacy R. Stewart

National Hurricane Center

14 December 2006

Chris was a tropical storm whose center remained north of the Lesser
Antilles before the cyclone weakened and moved across the Turks and
Caicos and the southeastern Bahamas as a tropical depression. Chris had
little impact on these areas.

a.  Synoptic History

    The tropical wave that eventually spawned Chris moved off the west
    coast of Africa early on 26 July, and maintained vigorous convection
    for the next couple of days as it moved westward at 15-20 kt. By
    late on 28 July, the convection weakened considerably and also
    became less organized as the system moved into a region of
    large-scale subsidence and drier air in the middle- and upper-levels
    of the troposphere. Although convective activity became
    disorganized, the wave's wind field remained well-defined. The wave
    continued to propagate westward at a slightly slower forward speed,
    and a small burst of deep convection developed on the northern end
    of the sharp wave axis early on 30 July about 550 n mi east of the
    southern Leeward Islands. Convection continued to increase in
    vertical depth and organization, and Dvorak satellite
    classifications were initiated by the Tropical Analysis and Forecast
    Branch at 1745 UTC. Late on 31 July, the system turned
    west-northwestward and convective organization rapidly increased. As
    the wave passed just north of French buoy 41100, the winds at the
    buoy switched direction from northeasterly to westerly, indicating a
    small surface low pressure area existed along the wave axis, which
    confirmed a similar signature in QuikSCAT wind data around 2100 UTC.
    It is estimated that a tropical depression formed at 0000 UTC 1
    August about 205 n mi east-southeast of Barbuda. 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 continued on a west-northwestward track at a slower
    forward speed of about 10 kt and, despite moderate upper-level
    westerly wind shear, strengthened into a tropical storm 6 h later.
    Aircraft reconnaissance flights into Tropical Storm Chris ensued
    around midday, and flight-level wind data indicated Chris had
    strengthened and become better organized. The cyclone reached its
    peak intensity of 55 kt early on 2 August about 55 n mi
    east-northeast of Anguilla in the northern Leeward Islands. Around
    midday on 3 August, a strong subtropical high pressure system to the
    north forced Chris westward, and the cyclone began to weaken as both
    westerly upper-level shear and dry air entrainment increased (Fig.
    4). Chris passed about 100 n mi north of Puerto Rico and Hispaniola
    and weakened to a tropical depression at 1800 UTC when the cyclone
    was centered about 195 n mi east-southeast of Grand Turk Island.

    As the depression moved westward toward Great Inagua Island in the
    southeastern Bahamas, increasing wind shear caused associated
    thunderstorm activity to dissipate and Chris degenerated into a
    non-convective remnant low pressure system by 0600 UTC August about
    80 n mi east-southeast of Grand Turk Island. The remnant circulation
    accelerated slightly as it skirted the northern coast of Cuba for
    the next 60 h before it dissipated at 1200 UTC 6 August near Havana,
    Cuba.

b.  Meteorological Statistics

    Observations in Tropical Storm Chris (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 (WRS) 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 QuikSCAT, and Defense Meteorological
    Satellite Program (DMSP) satellites were also useful in tracking
    Chris.

    There were a total of 31 aircraft center penetrations made by the
    53^rd^ WRS. In addition, there was one synoptic surveillance mission
    flown on 2-3 August by the NOAA Aircraft Operations Center
    Gulfstream-IV jet aircraft around the periphery of Chris. The
    estimated peak intensity for Chris of 55 kt on 2 August is based on
    an 850 mb flight-level wind of 67 kt, corresponding to about 54 kt
    at the surface. The minimum central pressure of 1001 mb is based on
    a dropsonde pressure of 1002 mb that was accompanied by a 15-kt
    surface wind, which indicates that the dropsonde probably did not
    sample the center of the cyclone and its lowest pressure.

    There were no ship reports of winds of tropical storm force
    associated with Chris. Selected surface observations from land
    stations are given in Table 3.

c.  Casualty and Damage Statistics

    Direct effects from Chris were mainly confined to brief periods of
    heavy rainfall and some localized floods. News reports indicate
    rainfall from the storm caused the [Fajardo
    River](http://en.wikipedia.org/w/index.php?title=Fajardo_River&action=edit)
    in Puerto Rico to overflow its banks, and the flood waters
    temporarily closed a highway in the northeastern portion of the
    island. Rainfall reached up to 2 in across portions of
    [Hispaniola](http://en.wikipedia.org/wiki/Hispaniola), the [Turks
    and Caicos](http://en.wikipedia.org/wiki/Turks_and_Caicos), the
    [Bahamas](http://en.wikipedia.org/wiki/Bahamas), and eastern
    [Cuba](http://en.wikipedia.org/wiki/Cuba). In some of the
    mountainous areas of Hispaniola, there were unofficial reports of
    near 4 in of rain. Although the center of Chris passed about 100 n
    mi to the north of [Dominican
    Republic](http://en.wikipedia.org/wiki/Dominican_Republic), the
    cyclone still caused heavy rainfall and significant floods in [Santo
    Domingo](http://en.wikipedia.org/wiki/Santo_Domingo). The floods
    left several people temporarily homeless due to water entering their
    homes, and many roads were impassable near the capital city due to
    the combined effects of high water and mud slides. Flood waters also
    covered rice fields in the northeastern portion of the country.
    Overall, damage was minor and there were no casualties reported in
    association with Chris.

    News reports indicate that there were indirect economic effects
    associated with the Chris official forecasts. Beginning on 2 August,
    NHC official forecasts projected Chris to move across the
    southeastern and central [Gulf of
    Mexico](http://en.wikipedia.org/wiki/Gulf_of_Mexico) as a category 1
    hurricane. In response to these forecasts, these price for crude oil
    rose on the [New York Mercantile
    Exchange](http://en.wikipedia.org/wiki/New_York_Mercantile_Exchange)
    at branch offices in [London](http://en.wikipedia.org/wiki/London).
    [Natural gas](http://en.wikipedia.org/wiki/Natural_gas) prices also
    rose considerably in New York Mercantile Exchange electronic trading
    that same day. Anticipation of a threat to supply by a potential
    Hurricane Chris coupled with high demand during an ongoing [heat
    wave](http://en.wikipedia.org/wiki/2006_North_American_heat_wave)
    were cited as factors in the price move.

d.  Forecast and Warning Critique

    The genesis of Chris was forecast quite well. Atlantic Tropical
    Weather Outlooks (TWOAT) from the National Hurricane Center began
    describing the area of disturbed weather from which Chris originated
    more than 4 days prior to when tropical cyclogenesis occurred.
    Possible formation of a tropical depression was explicitly mentioned
    at 0221 UTC 28 July, resulting in a lead time of more than 79 h.

    A verification of official and guidance model track forecasts is
    given in Table 4. Average official track (OFCL) errors for Chris
    were 27, 48, 63, 88, and 164 n mi for the 12, 24, 36, 48, and 72 h
    forecasts, respectively. The number of forecasts ranged from eleven
    at 12 h to only one at 72 h. These errors are lower than the average
    long-term official track errors (Table 4) at all times. The track
    forecasts showed little cross-track bias and correctly anticipated
    Chris' future path remaining north of the Caribbean island chain.
    The only models that significantly outperformed OFCL was the
    interpolated Navy NOGAPS (NGPI) and the 4-member GUNA consensus
    model.

    Average official intensity errors (Table 5) for Chris were 8, 18,
    19, 20, and 5 kt for the 12, 24, 36, 48, and 72 h forecasts,
    respectively. For comparison, the average long-term official
    intensity errors are 6.3, 9.8, 12.1, 14.8, 18.4, and 19.8 kt (Table
    5). The negative effects of vertical wind shear were anticipated
    from the outset and intensity forecasts were held lower than most of
    the available statistical and climatological models. However, the
    longer duration of the wind shear conditions and the effects of
    mid-level dry entrainment were not expected. This resulted in actual
    intensities being much lower than forecast, including prognoses of
    hurricane strength at forecast time periods when in actuality Chris
    no longer existed as a tropical cyclone. Overall, the OFCL intensity
    forecasts showed no skill and were beaten by nearly every model,
    including the 'zero-skill' SHIFOR model.

    Watches and warnings issued for Chris are listed in Table 2.

Acknowledgements:

Some of the data for this report was supplied by the NOAA National
Weather Service Forecast Office (WFO) in San Juan, Puerto Rico. News
reports were obtained from Bloomberg.com, FinancialNews.com, Univision
Television\--Puerto Rico, and ZeeNews.com.

Table 1. Best track for Tropical Storm Chris, 1-4 August 2006.

+---------+---------+---------+---------+---------+-----------------+
| Da      | L       | Lo      | P       | Wind    | Stage           |
| te/Time | atitude | ngitude | ressure | Speed   |                 |
|         |         |         |         |         |                 |
| (UTC)   | \(N\)   | \(W\)   | (mb)    | (kt)    |                 |
+---------+---------+---------+---------+---------+-----------------+
| 01 /    | 16.3    | 58.1    | 1011    | 30      | tropical        |
| 0000    |         |         |         |         | depression      |
+---------+---------+---------+---------+---------+-----------------+
| 01 /    | 16.8    | 58.9    | 1009    | 35      | tropical storm  |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 01 /    | 17.2    | 59.8    | 1006    | 40      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 01 /    | 17.7    | 60.6    | 1004    | 50      | \"              |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 02 /    | 18.1    | 61.4    | 1003    | 50      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 02 /    | 18.5    | 62.2    | 1001    | 55      | \"              |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 02 /    | 19.0    | 63.0    | 1001    | 55      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 02 /    | 19.6    | 63.9    | 1004    | 50      | \"              |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 03 /    | 19.9    | 64.8    | 1007    | 50      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 03 /    | 20.2    | 65.8    | 1010    | 40      | \"              |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 03 /    | 20.4    | 66.8    | 1011    | 35      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 03 /    | 20.6    | 67.7    | 1011    | 30      | tropical        |
| 1800    |         |         |         |         | depression      |
+---------+---------+---------+---------+---------+-----------------+
| 04 /    | 20.7    | 68.7    | 1011    | 30      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 04 /    | 20.8    | 70.2    | 1011    | 25      | low             |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 04 /    | 21.2    | 71.1    | 1011    | 25      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 04 /    | 21.3    | 72.2    | 1012    | 25      | \"              |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 05 /    | 21.5    | 73.4    | 1012    | 25      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 05 /    | 21.6    | 75.0    | 1012    | 20      | \"              |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 05 /    | 21.8    | 76.3    | 1012    | 20      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 05 /    | 22.1    | 77.6    | 1012    | 20      | \"              |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 06 /    | 22.4    | 78.9    | 1012    | 20      | \"              |
| 0000    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 06 /    | 22.8    | 80.2    | 1013    | 20      | \"              |
| 0600    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 06 /    | 23.2    | 81.7    | 1013    | 15      | \"              |
| 1200    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 06 /    |         |         |         |         | dissipated      |
| 1800    |         |         |         |         |                 |
+---------+---------+---------+---------+---------+-----------------+
| 02 /    | 18.5    | 62.2    | 1001    | 55      | minimum         |
| 0600    |         |         |         |         | pressure        |
+---------+---------+---------+---------+---------+-----------------+

Table 2. Watch and warning summary for Tropical Storm Chris, 1-4 August
2006.

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

  1 / 0300    Tropical Storm Watch issued    Saba, St. Barthelemy, St.
                                             Eustatius, St. Maarten, St.
                                             Martin

  1 / 0900    Tropical Storm Watch issued    Puerto Rico, U.S. Virgin
                                             Islands, British Virgin
                                             Islands

  1 / 0900    Tropical Storm Watch Changed   Saba, St. Barthelemy, St.
              to Tropical Storm Warning      Eustatius, St. Maarten, St.
                                             Martin

  1 / 0900    Tropical Storm Warning Issued  Anguilla, Antigua, Barbuda,
                                             Nevis, St. Kitts

  1 / 2100    Tropical Storm Watch changed   Puerto Rico, U.S. Virgin
              to Tropical Storm Warning      Islands, British Virgin
                                             Islands

  2 / 0600    Tropical Storm Warning         Saba, St. Eustatius
              discontinued                   

  2 / 0900    Tropical Storm Warning         Antigua, Barbuda, Nevis, St.
              discontinued                   Kitts

  2 / 1500    Tropical Storm Warning         Barthelemy, St. Maarten, St.
              discontinued                   Martin

  2 / 1500    Hurricane Watch issued         Turks and Caicos Islands, and
                                             Southeastern
                                             Bahamas...including Acklins,
                                             Crooked Island, Inaguas,
                                             Mayaguana, and Ragged Islands

  2 / 1800    Tropical Storm Warning         Anguilla
              discontinued                   

  3 / 0300    Tropical Storm Watch issued    Haiti/DR Border east to Cabo
                                             Engano of Hispaniola

  3 / 0900    Hurricane Watch downgraded to  Turks and Caicos Islands, and
              Tropical Storm Watch           Southeastern
                                             Bahamas...including Acklins,
                                             Crooked Island, Inaguas,
                                             Mayaguana, and Ragged Islands

  3 / 0900    Tropical Storm Warning         Puerto Rico, U.S. Virgin
              discontinued                   Islands, British Virgin
                                             Islands

  3 / 1500    Tropical Storm Watch           Cabo Francis Viejo west to
              discontinued                   Haiti/DR Border of Hispaniola

  3 / 1500    Tropical Storm Watch in effect Cabo Francis Viejo to Cabo
                                             Engano of Hispaniola

  4 / 0000    Tropical Storm Watch           Cabo Francis Viejo west to
              discontinued                   Haiti/DR Border, Cabo Samana
                                             east to Cabo Engano of
                                             Hispaniola

  4 / 0000    Tropical Storm Watch modified  Haiti/DR Border east to Samana
                                             of Hispaniola

  4 / 0300    Tropical Storm Watch upgraded  Turks and Caicos Islands, and
              to Tropical Storm Warning      Southeastern
                                             Bahamas...including Acklins,
                                             Crooked Island, Inaguas,
                                             Mayaguana, and Ragged Islands

  4 / 0300    Tropical Storm Watch issued    La Mole St. Nicolas east to
                                             Haiti/DR border of Hispaniola

  4 / 0300    Tropical Storm Watch issued    Long Island and Exumas in
                                             Central Bahamas

  4 / 1200    Tropical Storm Watch           La Mole St. Nicolas, Haiti
              discontinued                   eastward to Cabo Samana, DR of
                                             Hispaniola

  4 / 2100    Tropical Storm Warning         Turks and Caicos Islands, and
              discontinued                   all of Southeastern Bahamas

  5 / 0300    Tropical Storm Watch           Central Bahamas
              discontinued                   
  ----------- ------------------------------ ------------------------------

Table 3. Selected surface observations for Tropical Storm Chris, 1-4
August 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^ |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| **Bahamas**     |     |     |     |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Grand Turk      | 0   | 101 | 0   | 30    |     |     |     |     |
|                 | 4/1 | 2.5 | 4/1 |       |     |     |     |     |
|                 | 000 |     | 500 |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| **Puerto Rico** |     |     |     |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Cayey Lago      |     |     |     |       |     |     |     | 2   |
| Caritte USGS    |     |     |     |       |     |     |     | .39 |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Ceiba (TJNR)    | 0   | 101 |     |       |     |     |     | 1   |
| ASOS            | 3/0 | 5.2 |     |       |     |     |     | .05 |
|                 | 854 |     |     |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Fajardo USGS    |     |     |     |       |     |     |     | 3   |
|                 |     |     |     |       |     |     |     | .09 |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Jayuya USGS     |     |     |     |       |     |     |     | 1   |
|                 |     |     |     |       |     |     |     | .37 |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| Las Piedras     |     |     |     |       |     |     |     | 3   |
| USGS            |     |     |     |       |     |     |     | .08 |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| San Juan (TJSJ) | 0   | 101 |     |       |     |     |     | 0   |
| ASOS            | 3/0 | 4.6 |     |       |     |     |     | .53 |
|                 | 659 |     |     |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| San Juan Isla   |     |     |     |       |     |     |     | 2   |
| Grande USGS     |     |     |     |       |     |     |     | .93 |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| **U.S. Virgin   |     |     |     |       |     |     |     |     |
| Islands**       |     |     |     |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| St. Croix       | 0   | 101 |     |       |     |     |     | 0   |
| (TISX) ASOS     | 2/2 | 5.9 |     |       |     |     |     | .16 |
|                 | 100 |     |     |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| St. John        |     |     |     |       |     |     |     | 0   |
| --Bethany       |     |     |     |       |     |     |     | .00 |
| (USGS)          |     |     |     |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+
| St. Thomas      | 0   | 101 | 0   | 24    | 29  |     |     | 2   |
| (TIST) ASOS     | 3/0 | 4.6 | 2/2 |       |     |     |     | .26 |
|                 | 854 |     | 218 |       |     |     |     |     |
+-----------------+-----+-----+-----+-------+-----+-----+-----+-----+

^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).

Table 4. Preliminary forecast evaluation (heterogeneous sample) for
Tropical Storm

Chris, 1-4 August 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.

+-----------+-------+-------+-------+-------+-------+-------+-------+
| Forecast  | For   |       |       |       |       |       |       |
| Technique | ecast |       |       |       |       |       |       |
|           | P     |       |       |       |       |       |       |
|           | eriod |       |       |       |       |       |       |
|           | (h)   |       |       |       |       |       |       |
+===========+=======+=======+=======+=======+=======+=======+=======+
|           | 12    | 24    | 36    | 48    | 72    | 96    | 120   |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CLP5      | *     | *     | 72 (  | 90 (  | 204 ( |       |       |
|           | *26** | *47** | 7)    | 5)    | 1)    |       |       |
|           | (11)  | ( 9)  |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFNI      | *     | *     | *     | *     |       |       |       |
|           | *24** | *32** | *38** | *42** |       |       |       |
|           | ( 7)  | ( 5)  | ( 3)  | ( 1)  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFDI      | 35    | 66 (  | 87 (  | 98 (  |       |       |       |
|           | (10)  | 8)    | 6)    | 4)    |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GFSI      | 35    | 57 (  | 70 (  | *     | 228 ( |       |       |
|           | (11)  | 9)    | 7)    | *74** | 1)    |       |       |
|           |       |       |       | ( 5)  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| AEMI      | 32    | 58 (  | 66 (  | *     |       |       |       |
|           | (11)  | 9)    | 7)    | *68** |       |       |       |
|           |       |       |       | ( 5)  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NGPI      | *     | *     | *     | *     |       |       |       |
|           | *24** | *44** | *57** | *61** |       |       |       |
|           | ( 8)  | ( 6)  | ( 4)  | ( 2)  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| UKMI      | 30 (  | 75 (  |       |       |       |       |       |
|           | 4)    | 2)    |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| A98E      | *     | *     | *     | 100 ( | 258 ( |       |       |
|           | *26** | *41** | *61** | 5)    | 1)    |       |       |
|           | (11)  | ( 9)  | ( 7)  |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| A9UK      | 31 (  | 53 (  | 76 (  | 103 ( | 245 ( |       |       |
|           | 6)    | 5)    | 4)    | 3)    | 1)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMD      | 50    | 93 (  | 133 ( | 174 ( | 298 ( |       |       |
|           | (11)  | 9)    | 7)    | 5)    | 1)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMM      | 33    | 56 (  | 75 (  | *     | **    |       |       |
|           | (11)  | 9)    | 7)    | *79** | 119** |       |       |
|           |       |       |       | ( 5)  | ( 1)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| BAMS      | *     | 48 (  | 64 (  | *     | **    |       |       |
|           | *26** | 9)    | 7)    | *72** | 120** |       |       |
|           | (11)  |       |       | ( 5)  | ( 1)  |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| CONU      | 27    | *     | *     | *     |       |       |       |
|           | (11)  | *43** | *60** | *64** |       |       |       |
|           |       | ( 9)  | ( 7)  | ( 5)  |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| GUNA      | *     | *     |       |       |       |       |       |
|           | *15** | *33** |       |       |       |       |       |
|           | ( 4)  | ( 2)  |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| OFCL      | 27    | 48 (  | 63 (  | 88 (  | 164 ( |       |       |
|           | (11)  | 9)    | 7)    | 5)    | 1)    |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+
| NHC       | 37    | 65    | 91    | 118   | 171   | 231   | 303   |
| Official  |       |       |       |       |       |       |       |
|           | \(1   | \(1   | \(1   | \(1   | \(1   | \(    | \(    |
| (         | 930\) | 743\) | 569\) | 410\) | 138\) | 913\) | 742\) |
| 2001-2005 |       |       |       |       |       |       |       |
| mean)     |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+

Table 5. Preliminary intensity forecast evaluation (heterogeneous
sample) for Tropical Storm Chris, 1-4 August 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.

+--------+-------+--------+--------+--------+-------+-------+-------+
| Fo     | For   |        |        |        |       |       |       |
| recast | ecast |        |        |        |       |       |       |
| Tec    | P     |        |        |        |       |       |       |
| hnique | eriod |        |        |        |       |       |       |
|        | (h)   |        |        |        |       |       |       |
+========+=======+========+========+========+=======+=======+=======+
|        | 12    | 24     | 36     | 48     | 72    | 96    | 120   |
+--------+-------+--------+--------+--------+-------+-------+-------+
| SHF5   | 8.5   | **     | **     | **     | 25.0  |       |       |
|        | (11)  | 15.4** | 16.6** | 19.8** | ( 1)  |       |       |
|        |       | ( 9)   | ( 7)   | ( 5)   |       |       |       |
+--------+-------+--------+--------+--------+-------+-------+-------+
| GFDI   | 11.1  | **     | **     | **     |       |       |       |
|        | (10)  | 15.0** | 17.3** | 10.5** |       |       |       |
|        |       | ( 8)   | ( 6)   | ( 4)   |       |       |       |
+--------+-------+--------+--------+--------+-------+-------+-------+
| SHIP   | 8.5   | **     | **     | **     | 14.0  |       |       |
|        | (11)  | 16.2** | 16.6** | 17.6** | ( 1)  |       |       |
|        |       | ( 9)   | ( 7)   | ( 5)   |       |       |       |
+--------+-------+--------+--------+--------+-------+-------+-------+
| DSHP   | 8.5   | **     | **     | **     | **    |       |       |
|        | (11)  | 16.2** | 16.6** | 18.2** | 4.0** |       |       |
|        |       | ( 9)   | ( 7)   | ( 5)   | ( 1)  |       |       |
+--------+-------+--------+--------+--------+-------+-------+-------+
| FSSE   | 9.9   | **     | **     | **     |       |       |       |
|        | (10)  | 16.8** | 18.8** | 18.5** |       |       |       |
|        |       | ( 8)   | ( 6)   | ( 4)   |       |       |       |
+--------+-------+--------+--------+--------+-------+-------+-------+
| ICON   | 9.5   | **     | **     | **     |       |       |       |
|        | (10)  | 15.6** | 16.8** | 13.5** |       |       |       |
|        |       | ( 8)   | ( 6)   | ( 4)   |       |       |       |
+--------+-------+--------+--------+--------+-------+-------+-------+
| OFCL   | 8.2   | 17.8 ( | 19.3 ( | 20.0 ( | 5.0 ( |       |       |
|        | (11)  | 9)     | 7)     | 5)     | 1)    |       |       |
+--------+-------+--------+--------+--------+-------+-------+-------+
| NHC    | 6.3   | 9.8    | 12.1   | 14.3   | 18.4  | 19.8  | 21.8  |
| Of     |       |        |        |        | (     |       |       |
| ficial | \(1   | \(     | \(     | \(     | 1138) | \(    | \(    |
|        | 930\) | 1743\) | 1569\) | 1410\) |       | 913\) | 742\) |
| (200   |       |        |        |        |       |       |       |
| 1-2005 |       |        |        |        |       |       |       |
| mean)  |       |        |        |        |       |       |       |
+--------+-------+--------+--------+--------+-------+-------+-------+

![](media/image1.wmf){width="7.927777777777778in" height="6.1in"}

Figure 1. Best track positions for Tropical Storm Chris, 1-4 August
2006.

![](media/image2.wmf){width="7.7965277777777775in"
height="5.445833333333334in"}

Figure 2. Selected wind observations and best track maximum sustained
surface wind speed curve for Tropical

Storm Chris, 1-4 August 2006.

![](media/image3.wmf){width="7.922916666666667in"
height="5.4118055555555555in"}

Figure 3. Selected pressure observations and best track minimum central
pressure curve for Tropical

Storm Chris, 1-4 August 2006.

![](media/image4.wmf){width="5.441666666666666in" height="5.20625in"}

Figure 4. Microwave imagery from 1225 UTC 2 Aug 2006 SSMI (left) and
1722 UTC 2 AUG 2006 AMSR-E (right) overpasses showing the structure of
Chris in 85GHZ data (top panels). The left panels show Chris near its
peak intensity of 55 kt with a weak mid-level eye feature forming. The
lower panels show mid-level dry air (blue and green shades) wrapping
around the northern semicircle and intruding into the southwestern
quadrant toward the ceneter. (images from the U.S. Navy Research
Laboratory, Monterey, CA).