Carlotta was a category 4 hurricane (on the Saffir-Simpson scale) that had a long offshore track parallel to the coast of Mexico. Its maximum winds of 135 kt make Carlotta the second strongest June hurricane (to Ava in 1973) in the east Pacific record since 1966. Although the hurricane did not make landfall, it was responsible for 18 deaths when the Lithuanian freighter M/V Linkuva was caught in the hurricane and was lost at sea.
a. Synoptic History
A tropical wave that emerged from the coast of Africa on June 3rd, and crossed into the eastern Pacific basin on the 15th, appears to have been the precursor disturbance of Hurricane Carlotta. Surface analyses show a weak low beginning late on the 16th near 8N, 88W, and Dvorak satellite classifications began around 1200 UTC on the 17th. Convection was broadly distributed and disorganized, however, until about 1200 UTC on the 18th, when a concentration of deep convection developed just south of the Gulf of Tehuantepec. Ship reports and satellite scatterometer data suggest that the season's third tropical depression formed from this system by 1800 UTC about 235 n mi southeast of Puerto Angel, Mexico.
The best track chart of the tropical cyclone's path is given in Figure 1, with the wind and pressure history shown in Figure 2 and Figure 3, respectively. The complete best track is given in Table 1. The depression strengthened as it moved to the west-northwest at about 11 kt, and became Tropical Storm Carlotta at 0000 UTC 19 June when the cyclone was centered about 180 n mi south-southeast of Puerto Angel. As Carlotta edged toward the coast, it came under the influence of a mid-tropospheric ridge to its north and turned slightly to the left; its closest approach to the Mexican coast was about 120 n mi near 1200 UTC on the 19th. Late on the 19th, a ragged banding eye became visible on satellite imagery and this was followed by the appearance of very deep convection around the developing eye. Carlotta reached hurricane status at 0600 UTC on the 20th, when it was about 135 n mi south of Acapulco. Once hurricane strength was attained, the pace of intensification increased dramatically; 24 h later at 0600 UTC on the 21st, Carlotta reached its peak intensity of 135 kt. Although Carlotta exhibited impressive upper-level outflow over its southern semicircle, outflow was limited to the north of the cyclone during most of the intensification period.
Shortly after reaching peak intensity, Carlotta turned from a general westerly heading to a west-northwest track at a reduced speed, about 7-8 kt, around the western edge of the mid-tropospheric ridge over Mexico. By 0000 UTC on the 22nd, Carlotta had weakened to about 100 kt. On the 22nd the weakening trend was temporarily halted with some oscillations in the convective intensity and eye definition. The weakening trend resumed for good on the 23rd. Over the next two days, Carlotta moved to the northwest between 10 and 14 kt over cooler waters, falling below hurricane strength shortly after 0000 UTC on the 24th, when it was centered about 225 n mi west-southwest of Cabo San Lucas. Convection continued to diminish and the system became a tropical depression by 0000 UTC on the 25th. No further deep convection was noted after 0600 UTC on the 25th, when the tropical cyclone dissipated about 415 n mi west of Cabo San Lucas. A swirl of low clouds persisted in this area for several days thereafter.
b. Meteorological Statistics
Observations in Hurricane Carlotta (Figure 2 and Figure 3) include satellite 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). In addition, flight-level and dropwindsonde observations were available from a flight of the 53rd Weather Reconnaissance Squadron of the U. S. Air Force Reserve Command.
Of particular interest is a comparison of the aircraft and satellite-based intensity estimates during the period of reconnaissance coverage from about 1900-2200 UTC on the 20th. It is clear that the satellite intensity estimates were substantially in error, having overstated the intensity of Carlotta during this period by about 20 mb and 15-20 kt. The reconnaissance aircraft measured a minimum sea-level pressure of 977 mb at 1901 UTC, while the Dvorak estimate from TAFB and SAB (interpolated to the time of the reconnaissance fix) was about 20 mb lower. Similarly, the Dvorak-based maximum wind estimate at this time was about 105 kt, while the aircraft found peak flight-level winds no higher than 96 kt (estimated equivalent of 86 kt at the surface) during its first full "alpha" pattern. A GPS dropwindsonde at 2040 UTC in the northwest eyewall, where the maximum flight-level winds were found during the first alpha pattern, reported a surface wind of 91 kt, about 17 kt less than the satellite estimate (interpolated to the time of the drop).
The aircraft did find that Carlotta was deepening rapidly; from 1901 to 2142 UTC the minimum pressure fell by 7-8 mb to 970 mb, representing a deepening rate of just less than 3 mb h-1. At 2146 UTC, the aircraft reported a flight-level wind of 105 kt (estimated equivalent of 95 kt at the surface). By this time, however, the satellite intensity estimates had also increased, to 110 kt and about 952 mb.
The sizable discrepancy between the satellite and reconnaissance estimates makes determining the maximum intensity of Carlotta problematic, as satellite imagery indicates that Carlotta continued to strengthen rapidly for another 9 hours or so after the conclusion of the reconnaissance coverage. Conventional Dvorak estimates reached 140 kt (921 mb) at 0600 UTC on the 21st, and the University of Wisconsin objective Dvorak 12-h weighted average estimate peaked at this time with a value of 146 kt (915 mb). For purposes of determining the best track intensity, it is assumed that the satellite high bias was present for about 24 hours before and after the time of the reconnaissance flight. Using this approach, the maximum intensity of Carlotta is estimated to have been 135 kt. The estimated time of peak intensity (0600 UTC 21 June) is based on the sequence of objective Dvorak numbers.
There is considerable uncertainty regarding the minimum pressure attained by Carlotta. The Dvorak pressure-wind curve associates a pressure of 926 mb with winds of 135 kt. However, a comparison of reconnaissance winds and pressures suggests that the observed pressures in Carlotta were 5-10 mb higher than those predicted by the Dvorak pressure-wind curve. Therefore, the minimum pressure, which occurred shortly thereafter, is believed to be somewhat higher than 926 mb. The final value of 932 mb at 0600 UTC on the 21st was obtained by assuming a deepening rate of 5 mb h-1 subsequent to the best track estimate of 962 mb at 21/0000 UTC. This assumed deepening rate is close to the extreme short term intensification rates observed in 1988's Hurricane Gilbert and 1995's Hurricane Opal, and as a result, the assigned 932 mb minimum pressure for Carlotta probably represents a lower bound on the true value.
Ship reports of winds of tropical storm force associated with Carlotta are listed in Table 2. No land stations reported sustained tropical storm force winds. Bahias De Huatulco (MMBT) reported a gust to 38 kt at 1300 UTC on June 19th.
c. Casualty and Damage Statistics
According to media reports, the Lithuanian freighter M/V Linkuva, along with its crew of 18 persons, was lost when the ship was caught in the hurricane 220 miles southwest of Acapulco late on June 20th after an engine failure. The last contact with the M/V Linkuva occurred during the period of rapid intensification and just before the Carlotta reached its peak intensity. The vessel was en route to Long Beach, California.
There are no other reports of damage or casualties.
Forecast and Warning Critique
Average official track errors for Carlotta were 29, 59, 92, 110, and 124 n mi for the 12, 24, 36, 48, and 72 h forecasts, respectively; these were somewhat lower than the average official track errors for the 10-yr period 1990-1999 (Table 3). However, the track errors for Carlotta were somewhat larger than the guidance from the UK Met. Office global model (UKMI). The GFDL model had a significant rightward bias with errors much larger than the official forecast, presumably due to a poor vortex initialization in the Aviation model. Although the official track forecast errors were smaller than the long-term mean, Fig. 4 shows that the three modest changes in Carlotta's track: the initial leftward turn near 96W, the turn to the northwest near 106W, and the final leftward turn near 114W, were not well anticipated.
Figure 5 shows selected official intensity forecasts plotted against the best track. The initial intensification to hurricane strength was well forecast; however, the rapid strengthening to category 4 was not, even after the process was underway. The worst forecast errors (all underestimates) for the 12, 24, 36, 48, and 72 h forecasts were 40, 45, 50, 60, and 50 kt, respectively. Neither the SHIPS nor GFDL guidance models forecast the rapid strengthening to category 4. The decay stage was reasonably-well forecast.
Table 4 lists the watches and warnings associated with Carlotta issued by the government of Mexico. As noted above, no sustained tropical storm force winds were observed over land.
Table 1. Best track for Hurricane Carlotta, 18-25 June 2000. Date/Time
(UTC)Position Pressure
(mb)Wind Speed
(kt)Stage Lat. (°N) Lon. (°W) 18 / 1800 12.5 94.0 1003 30 tropical depression 19 / 0000 13.0 95.0 1002 35 tropical storm 19 / 0600 13.5 96.1 1000 45 " 19 / 1200 13.8 97.2 998 50 " 19 / 1800 14.1 98.3 995 55 " 20 / 0000 14.3 99.3 992 60 " 20 / 0600 14.5 100.2 989 65 hurricane 20 / 1200 14.7 101.2 985 75 " 20 / 1800 14.9 102.1 981 85 " 21 / 0000 15.1 103.1 962 110 " 21 / 0600 15.1 103.8 932 135 " 21 / 1200 15.3 104.5 934 135 " 21 / 1800 15.6 105.3 938 130 " 22 / 0000 15.9 106.0 949 115 " 22 / 0600 16.3 106.6 960 100 " 22 / 1200 16.8 107.2 960 100 " 22 / 1800 17.3 107.9 960 100 " 23 / 0000 17.9 108.7 960 100 " 23 / 0600 18.6 109.6 963 95 " 23 / 1200 19.4 110.5 970 85 " 23 / 1800 20.3 111.5 979 75 " 24 / 0000 21.2 112.7 987 65 " 24 / 0600 22.0 113.8 994 55 tropical storm 24 / 1200 22.6 114.8 999 45 " 24 / 1800 23.2 115.8 1002 35 " 25 / 0000 23.6 116.6 1004 30 tropical depression 25 / 0600 24.0 117.3 1006 25 " 21 / 0600 15.1 103.8 932 135 minimum pressure
Table 2. Ship reports with winds of at least 34 kt for Hurricane Carlotta, 18-25 June 2000. Date/ Time
(UTC)Ship Call Sign Lat. (°N) Lon. (°W) Wind dir/speed
(deg/kt)Pressure
(mb)18/1800 4XGT 13.2 93.8 070/35 1008.8 19/1800 KAOU 15.0 98.0 070/36 1010.0 19/2100 KAOU 15.0 98.0 090/40 1008.0 20/0000 KAOU 15.1 98.1 110/35 1009.1 20/1500 OWZU2 16.8 100.8 100/35 1010.0 21/1500 4XFD 18.1 103.4 090/40 1011.0 22/0000 DGOS 17.9 103.4 090/34 1011.0 23/0000 JFUG 19.8 106.0 120/39 1009.3 23/0600 ELWZ5 20.7 106.8 140/35 1012.0
Table 3. Preliminary forecast evaluation (heterogeneous sample) for Hurricane Carlotta, 18-25 June 2000. Forecast errors for tropical storm and hurricane stages (n mi) are followed by the number of forecasts in parentheses. Errors smaller than the NHC official forecast are shown in bold-face type. Forecast Technique Period (hours) 12 24 36 48 72 CLIP 31 (22) 64 (20) 109 (18) 148 (16) 191 (12) GFDI 43 (22) 105 (20) 196 (18) 226 (14) 325 (8) LBAR 26 (22) 60 (20) 113 (18) 176 (16) 312 (12) AVNI 46 (15) 102 (15) 168 (12) 109 (3) 147 (3) BAMD 34 (22) 57 (20) 86 (18) 125 (16) 210 (12) BAMM 30 (22) 49 (20) 86 (18) 135 (16) 262 (12) BAMS 30 (22) 45 (20) 73 (18) 117 (16) 233 (12) NGPI 42 (21) 100 (19) 95 (15) 134 (13) 201 (5) UKMI 26 (20) 44 (18) 68 (16) 93 (14) 132 (10) GUNS 29 (20) 66 (18) 72 (14) 80 (12) 89 (4) NHC Official 29 (22) 59 (20) 92 (18) 110 (16) 124 (12) NHC Official (1990-99 mean) 37 (2494) 69 (2245) 101 (1993) 132 (1760) 189 (1353)
Table 4. Watch and warning summary for Hurricane Carlotta, 18-25 June 2000. Date/Time
(UTC)Action Location 18 / 2100 Tropical Storm Warning issued Salina Cruz to Acapulco 19 / 0900 Hurricane Watch issued Puerto Angel to Zihuatanejo 19 / 0900 Tropical Storm Warning extended Acapulco to Zihuatanejo 19 / 1800 Tropical Storm Warning discontinued Salina Cruz to Puerto Angel 20 / 0300 Hurricane Watch discontinued Puerto Angel to Acapulco 20 / 0900 Hurricane Watch discontinued Acapulco to Zihuatanejo 20 / 1200 Tropical Storm Warning discontinued Puerto Angel to Acapulco 20 / 1500 Tropical Storm Warning discontinued Acapulco to Zihuatanejo 23 / 0900 Tropical Storm Watch issued Baja California south of Cabo San Lazaro 23 / 2100 Tropical Storm Watch discontinued Baja California south of Cabo San Lazaro
Figure 1. Best track positions for Hurricane Carlotta, 18-25 June 2000.
Figure 2. Best track maximum sustained surface wind speed curve for Hurricane Carlotta, 18-25 June 2000, and the observations on which the best track curve is based. Aircraft observations have been adjusted for elevation using 90%, 80%, and 85% 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 sounding boundary layer mean (MBL). Objective Dvorak estimates are 12-h averages, weighted most heavily by the most recent values.
Figure 3. Best track minimum central pressure curve for Hurricane Carlotta, 18-25 June 2000, and the observations on which the best track curve is based. Objective Dvorak estimates are 12-h averages, weighted most heavily by the most recent values.
Figure 4. Selected official track forecasts (dashed lines, with 0, 12, 24, 36, 48, and 72 h positions indicated) for Hurricane Carlotta, 18-25 June 2000. The best track is given by the thick solid line with positions given at 6 h intervals.
Figure 5. Selected official intensity forecasts (dashed lines) for Hurricane Carlotta, 18-25 June 2000. The best track intensity is given by the thick solid line.
