Skip Navigation Links weather.gov   
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
National Hurricane Center
Local forecast by
"City, St" or "ZIP"

 
Alternate Formats
   Text     |   Mobile
   Email   |   RSS XML/RSS logo
   About Alternates
Cyclone Forecasts
   Latest Advisory
   Past Advisories
   Audio/Podcasts
   About Advisories
Marine Forecasts
   Atlantic & E Pacific
   Gridded Marine
   About Marine
Tools & Data
   Satellite | Radar
   Analysis Tools
   Aircraft Recon
   GIS Datasets
   Data Archive
Development
   Experimental
   Research
   Forecast Accuracy
Outreach & Education
   Prepare
   Storm Surge
   About Cyclones
   Cyclone Names
   Wind Scale
   Most Extreme
   Forecast Models
   Breakpoints
   Resources
   Glossary | Acronyms
   Frequent Questions
Our Organization
   About NHC
   Mission & Vision
   Staff | Q&A
   Visitors | Virtual Tour
   Library Branch
   NCEP | Newsletter
Contact Us
   Comments
Follow the National Hurricane Center on Facebook Follow the National Hurricane Center on Twitter
Subscribe the National Hurricane Center on YouTube Read the National Hurricane Center Inside the Eye blog on WordPress
FirstGov.gov is the U.S. Government's official Web portal to all Federal, state and local government Web resources and services.
 
 

Tropical Cyclone Report

Hurricane Darby

26 July - 1 August 2004

Jack Beven
National Hurricane Center
13 December 2004

Darby reached category 3 status on the Saffir-Simpson Hurricane Scale over the open eastern North Pacific ocean.

a. Synoptic History

Darby formed from a tropical wave that moved westward across the coast of Africa on 12 July. The wave crossed the Atlantic and Caribbean with no development and reached the eastern North Pacific on 20 July. Moving westward, the system first showed signs of organization on 23 July. Continued slow development resulted in the formation of a tropical depression around 1200 UTC 26 July about 660 n mi south-southwest of Cabo San Lucas, Mexico. The "best track" chart of the tropical cyclone's path is given in Figure 1, with the wind and pressure histories shown in Figure 2 and Figure 3, respectively. The best track positions and intensities are listed in Table 1.

The depression moved westward on the south side of the subtropical ridge and became a tropical storm early on 27 July. It turned west-northwestward later that day and continued to strengthen. Darby became a hurricane early on 28 July, and then reached an estimated peak intensity of 105 kt on 29 July. The hurricane started to weaken later that day due to a combination of cooler sea-surface temperatures and increasing westerly vertical shear. It became a tropical storm again on 30 July as it turned westward, and it weakened to a depression on 31 July. The depression crossed 140°W into the central North Pacific hurricane basin later that day. Darby dissipated as a tropical cyclone on 1 August about 740 n mi east of the Hawaiian Islands. The remnants of Darby continued westward in the low-level trade winds and caused heavy rains and flooding over portions of the Hawaiian Islands on 3-4 August.

b. Meteorological Statistics

Observations in Darby (Figure 2 and Figure 3) include satellite-based Dvorak technique intensity estimates from the Tropical Analysis and Forecast Branch (TAFB), the Satellite Analysis Branch (SAB) and the U. S. Air Force Weather Agency (AFWA). Microwave satellite imagery from NOAA polar-orbiting satellites, the NASA Tropical Rainfall Measuring Mission (TRMM), the NASA Aqua, the NASA QuikSCAT, and Defense Meteorological Satellite Program (DMSP) satellites were also useful in tracking Darby.

There were no surface observations of winds of tropical storm force from Darby.

c. Casualty and Damage Statistics

There were no reports of damages or casualties associated with Darby.

d. Forecast and Warning Critique

Average official track errors (with the number of cases in parentheses) for Darby were 19 (21), 36 (19), 58 (17), 80 (15), 127 (11), 206 (7), and 333 (3) n mi for the 12, 24, 36, 48, 72, 96, and 120 h forecasts, respectively. These errors are lower than the average official track errors for the 10-yr period 1994-2003[1] (38, 70, 100, 127, 180, 210, and 247 n mi, respectively) through 96 h, but much greater than the average 120 h error. The large errors at 120 h resulted from the early track forecasts being too far south and too slow.

Average official intensity errors were 7, 11, 13, 15, 21, 31 and 40 kt for the 12, 24, 36, 48, 72, 96, and 120 h forecasts, respectively. For comparison, the average official intensity errors over the 10-yr period 1994-2003 are 6, 11, 15, 17, 20, 18, and 19 kt, respectively. The large errors at 96 and 120 h resulted from early intensity forecasts making Darby too strong.

Watches and warnings were not required for Darby.

Acknowledgements

The best track west of 140°W was provided by the Central Pacific Hurricane Center in Honolulu, Hawaii.


[1]Errors given for the 96 and 120 h periods are averages over the three-year period 2001-3.

Table 1: Best track for Hurricane Darby, 26 July - 1 August 2004.
Date/Time
(UTC)
PositionPressure
(mb)
Wind Speed
(kt)
Stage
Lat.
(°N)
Lon.
(°W)
 26 / 1200 12.2 112.8 1008 25 tropical depression
 26 / 1800 12.3 114.2 1007 30 "
 27 / 0000 12.5 115.5 1003 35 tropical storm
 27 / 0600 12.9 116.8 1000 45 "
 27 / 1200 13.2 118.0 993 55 "
 27 / 1800 13.6 119.1 990 60 "
 28 / 0000 14.1 120.5 987 65 hurricane
 28 / 0600 14.6 121.7 983 70 "
 28 / 1200 15.2 122.8 977 80 "
 28 / 1800 15.8 124.0 970 90 "
 29 / 0000 16.3 125.2 964 95 "
 29 / 0600 16.8 126.2 957 105 "
 29 / 1200 17.4 127.2 960 100 "
 29 / 1800 17.8 128.2 964 95 "
 30 / 0000 18.1 129.2 980 75 "
 30 / 0600 18.3 130.3 987 65 "
 30 / 1200 18.4 131.7 994 55 tropical storm
 30 / 1800 18.6 133.2 998 45 "
 31 / 0000 18.7 134.6 1000 40 "
 31 / 0600 18.8 136.0 1002 35 "
 31 / 1200 18.8 137.3 1005 30 tropical depression
 31 / 1800 18.9 138.8 1007 25 "
 01 / 0000 19.0 140.4 1007 25 "
 01 / 0600 19.3 142.0 1007 25 "
 01 / 1200     dissipated
 29 / 0600 16.8 126.2 957 105 minimum pressure


Table 2: Preliminary forecast evaluation (heterogeneous sample) for Hurricane Darby, 26 July - 1 August 2004. Forecast errors (n mi) are followed by the number of forecasts in parentheses. Errors smaller than the NHC official forecast (OFCL) are shown in bold-face type. Verification includes the depression stage, but does not include the extratropical stage, if any.
Forecast TechniquePeriod (hours)
122436487296120
CLP529 (22) 58 (20) 93 (18) 130 (16) 125 (12) 204 (8)322 (4)
GFDI28 (22) 55 (20) 85 (18) 115 (16) 179 (12) 292 (8) 458 (4) 
GFDL*31 (20) 53 (18) 72 (17) 97 (15) 151 (11) 250 (7) 368 (3) 
GFNI28 (16) 45 (16) 55 (14)72 (12)117 (8)205 (4) 
GFDN*33 (8) 54 (8) 68 (8) 71 (7)103 (5)181 (3)321 (1)
AF1I37 (15) 67 (13) 117 (11) 177 (9) 272 (5)   
AFW1*54 (8) 80 (7) 100 (6) 144 (5) 259 (3)   
COEI65 (2) 120 (1) 125 (1)     
COCE*89 (1) 139 (1)      
LBAR30 (22) 52 (20) 83 (18) 113 (16) 156 (12) 127 (8)160 (4)
P91E26 (22) 51 (20) 89 (18) 125 (16) 178 (12) 222 (8) 311 (4)
P9UK27 (11) 51 (10) 83 (9) 105 (8) 116 (6)  
BAMD41 (22) 81 (20) 124 (18) 164 (16) 243 (12) 316 (8) 395 (4) 
BAMM27 (22) 55 (20) 84 (18) 101 (16) 126 (12) 179 (8)264 (4)
BAMS32 (22) 50 (20) 70 (18) 86 (16) 121 (12) 127 (8)167 (4)
NGPI39 (22) 74 (20) 103 (18) 129 (16) 160 (10) 291 (6) 468 (2) 
NGPS*32 (21) 60 (19) 85 (17) 114 (15) 151 (11) 259 (7) 433 (3) 
UKMI28 (19) 51 (17) 64 (15) 67 (13)69 (9)86 (5)62 (1)
UKM*47 (10) 66 (9) 86 (8) 86 (7) 71 (5)103 (3)83 (1)
GFSI42 (20) 86 (17) 111 (15) 131 (13) 191 (10) 227 (6) 174 (2)
GFS*58 (21) 86 (18) 107 (14) 128 (12) 171 (10) 201 (5)201 (3)
AEMI34 (15) 60 (13) 72 (11) 83 (9) 138 (7) 180 (3) 
AEMN*39 (16) 72 (14) 81 (12) 83 (10) 104 (8)108 (4) 
GUNS22 (19) 39 (17) 56 (15)74 (13)109 (9)191 (5)286 (1)
GUNA22 (19) 42 (16) 52 (14)67 (12)86 (9)144 (5)234 (1)
CONU30 (22) 55 (20) 73 (18) 92 (16) 94 (10)153 (6)276 (2)
OFCI22 (20) 42 (18) 66 (16) 90 (14) 138 (10) 221 (6) 363 (2) 
OFCL19 (21) 36 (19) 58 (17) 80 (15) 127 (11) 206 (7) 333 (3) 
NHC Official (1994-2003 mean)38 (2746) 70 (2474) 100 (2196) 127 (1928) 180 (1476) 210 (283) 247 (179) 

*Output from these models was unavailable at forecast time.

Best track positions for Hurricane Darby

Figure 1: Best track positions for Hurricane Darby, 26 July - 1 August 2004. The best track west of 140°W was provided by the Central Pacific Hurricane Center in Honolulu, Hawaii.

Selected wind observations and best track maximum sustained surface wind speed curve for Hurricane Darby

Figure 2: Selected wind observations and best track maximum sustained surface wind speed curve for Hurricane Darby, 26 July - 1 August 2004. Objective Dvorak estimates represent linear averages over a three-hour period centered on the nominal observation time. The best track west of 140°W was provided by the Central Pacific Hurricane Center in Honolulu, Hawaii.

Selected pressure observations and best track minimum central pressure curve for Hurricane Darby

Figure 3: Selected pressure observations and best track minimum central pressure curve for Hurricane Darby, 26 July - 1 August 2004. Objective Dvorak estimates represent linear averages over a three-hour period centered on the nominal observation time. The best track west of 140oW was provided by the Central Pacific Hurricane Center in Honolulu, Hawaii.



Quick Navigation Links:
Tropical Cyclone Forecasts  -  Tropical Marine Forecasts  -  Data Archive
Outreach  -  Prepare  -  About Cyclones  -  About NHC  -  Contact Us

NOAA/ National Weather Service
National Centers for Environmental Prediction
National Hurricane Center
11691 SW 17th Street
Miami, Florida 33165-2149 USA
nhcwebmaster@noaa.gov
Disclaimer
Credits
Information Quality
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities
Page last modified: Tuesday, 15-Mar-2005 21:06:16 UTC