a. Synoptic History
Madeline can be traced back to a tropical wave
that emerged from the west coast of Africa on 25 September. The wave produced intermittent clusters of convection
as it moved across the Atlantic and Caribbean Sea. Cloudiness associated with the wave crossed over Central America on 5
and 6 October. Convection increased in the vicinity of the Gulf of Tehuantepec on 9 October, and
Dvorak classifications began on this day. Satellite classifications
temporarily ceased on 11 October, although disorganized cloudiness persisted off the southwest coast of Mexico.
Classifications resumed on 15 October and the "best track" indicates that a
tropical depression formed from the disturbance near
0000 UTC 16 October while centered about 200 n mi west-southwest of Manzanillo, Mexico (Fig. 1
[21K GIF] and Table 1).
Under diffluent conditions aloft, the deep convection became more concentrated and
satellite estimates suggest that the depression strengthened into Tropical Storm
Madeline at 1200 UTC 16 October while centered about 150 n mi southwest of Cabo Corrientes, Mexico. Banding features
became more pronounced and Madeline became a hurricane at 1800 UTC 17 October while
centered about 85 n mi west-southwest of Cabo Corrientes. Upper-level outflow remained well-established, and
it is estimated that the maximum winds in Madeline reached 75 knots
from 1200 UTC 18 October to 0000 UTC 19 October. Satellite pictures showed a hint of an eye
on the 18th, and the last report from a reconnaissance aircraft reported that the minimum central pressure was
continuing to drop late that day. The best track estimates that the lowest pressure of 979 mb occurred at
0000 UTC 19 October.
Upper-level shear increased during the 19th, and the cloud pattern began looking
somewhat ragged. Madeline weakened to a tropical storm by 1200 UTC 19 October, and to a tropical
depression twelve hours later, at which time only a swirl of low clouds was left of it midway between the
southern tip of Baja California and the mainland of Mexico. The center
of the tropical cyclone never
crossed the coast, although rainbands moved over portions of southwestern Mexico.
Steering currents surrounding the tropical cyclone were relatively weak throughout its
lifetime. In the early stages, Madeline was located near the western edge of an east-west oriented
mid-level ridge which resulted in a general northward motion of the cyclone. On the 17th and 18th,
a mid-level trough approaching from the west appears to be the reason for a slow northeastward motion. The
trough did not move the tropical cyclone far before shearing occurred, however, and the lower-level
steering eventually turned the weakening Madeline toward the northwest.
b. Meteorological Statistics
Figures 2 (17K GIF) and 3
(17K GIF) show the curves of minimum central pressure and
maximum one-minute wind speed, respectively, versus time, along with the observations on which they
are based. As usual for an eastern Pacific tropical cyclone,
satellites provided the primary source of observational data.
Dvorak technique location and intensity estimates from the satellite data were
produced by the Air Force Weather Agency (AFGWC in figures),
the NOAA Synoptic Analysis Branch
(SAB) and the NOAA Tropical Analysis and Forecast Branch (TAFB). The highest official Dvorak T
number was 4.5 (77 knots) from TAFB, SAB and AFGWC.
In addition to the satellite estimates, observations were received from U.S.
Air Force "Hurricane Hunter"
aircraft.
The lowest minimum central pressure reported was 980 mb at 2153 UTC
18 October during the second of two missions into the hurricane. The maximum wind measured was
76 knots from a flight level of 10,000 feet at 2028 UTC on the 18th. A
near-surface wind of 73 knots was reported by one of the GPS
dropwindsondes near this time.
c. Casualty and Damage Statistics
There were no reports of casualties or damages from Madeline received at the NHC.
d. Forecast and Warning Critique
The NHC average official track forecast errors for Madeline (excluding the tropical
depression stage) were 38 (12 cases), 81 (10 cases), 137 (8 cases), 186 (6 cases) and 313 n mi (2 cases),
respectively, for the 12-, 24-, 36-, 48- and 72-hour forecast periods. Although the sample size is small,
these errors were larger than the 1988-1997 average errors except at 12 hours for which the errors are
comparable. The NHC average official track forecast errors were similar to or lower than the averages
from most of the operationally available track prediction models through 48 hours. The exception was
the UKMI guidance which was 48 n mi lower than the official forecast at 48 hours for a homogeneous
sample of five. No meaningful comparisons can be made at 72 hours due to the small number of
forecasts made for that time period. The relatively large errors from the official track forecasts as well as
the track guidance are not unusual for a northward moving tropical cyclone in the eastern North Pacific.
The need for improvement in track forecasts for a hurricane like Madeline near land and in an area of
heavy marine traffic is obvious.
The NHC official intensity forecasts showed a negative bias (i.e., intensity was
underestimated) while Madeline was strengthening and a distinct positive bias (i.e., intensity was
overestimated) while Madeline was weakening. For example, the 48-hour intensity forecast issued about
two days before maximum intensity was reached was 40 knots too low. On the other hand, the 12- and
24-hour intensity forecasts issued near the time of maximum intensity were 40 knots too high. These
larger than usual short-period intensity forecast errors were the result of the inability to forecast rapid
weakening.
Table 2 summarizes the watches and warnings issued for Madeline.
Table 2. Watch and warning summary, Hurricane Madeline, October 1998.
Date/time
(UTC) | Action | Location |
| 16/1500 | tropical storm warning issued |
Baja California from La Paz southward |
| hurricane watch issued | Baja California from La Paz southward |
| 17/0900 | hurricane watch issued |
Mazatlan to Los Mochis, Mexico |
| 17/1500 | hurricane warning issued |
Melaque to Mazatlan, Mexico including the Islas Marias |
| tropical storm warning discontinued | Baja California from La Paz southward |
| 19/0300 | hurricane warning discontinued |
Melaque to just southeast of Cabo Corrientes |
| hurricane warning extended northwestward | Mazatlan to El Dorado, Mexico |
| 19/1500 | hurricane warning discontinued |
Cabo Corrientes to San Blas, Mexico |
| 19/1800 |
hurricane warning downgraded to tropical storm warning |
north of San Blas to El Dorado, Mexico including the Islas Marias |
| hurricane watch downgraded to tropical storm watch |
northwest of El Dorado to Los Mochis,Mexico |
| hurricane watch downgraded to tropical storm watch |
Baja California from La Paz southward |
| 20/0000 | all remaining tropical storm watches and warnings discontinued |
|
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