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Preliminary Report
Hurricane Ismael
12-15 September 1995

Max Mayfield
National Hurricane Center
19 November 1995


PRELIMINARY REPORTS
Tropical Depression One-E
Hurricane Adolph
Hurricane Barbara
Hurricane Cosme
Tropical Storm Dalila
Tropical Storm Erick
Hurricane Flossie
Tropical Storm Gil
Hurricane Henriette
Hurricane Ismael
Hurricane Juliette


[1995 East Pacific Hurricane Season]

Hurricane Ismael, a short-lived Category 1 hurricane on the Saffir/Simpson Hurricane Scale that made landfall near Topolobampo, Mexico, resulted in a large loss of life in the Gulf of California.

a. Synoptic History

Satellite imagery showed a poorly organized area of cloudiness and showers centered about 150 n mi south of the coast of Guatemala on 9 September. The tropical disturbance moved slowly west-northwestward for the next couple of days without signs of development. On 12 September a cloud system center became evident in satellite imagery, and analysts from both the NESDIS Synoptic Analysis Branch (SAB) and the NHC began Dvorak classifications at 1200 UTC on this day.

Convective banding became organized and the "best track" (Figure 1 [48K GIF] and Table 1) indicates that a tropical depression formed at 1800 UTC 12 September about 300 n mi south-southwest of Manzanillo, Mexico. The depression began to move toward the northwest near 7 knots.

Deep convection increased near the center, and satellite intensity estimates suggest that the depression strengthened into Tropical Storm Ismael at 0000 UTC 13 September. The storm turned more toward the north, apparently in response to a mid- to upper-level low over Baja California observable in water vapor imagery.

Upper-level outflow became well-established as deep convection continued to develop on 13 and 14 September. It is estimated that Ismael strengthened into a hurricane while centered about 250 n mi south-southeast of the southern tip of Baja California at 0600 UTC 14 September. Satellite analysts at both SAB and NHC indicated hurricane intensity at this time. On the 14th a poorly-defined eye became visible in satellite pictures, and Ismael is estimated to have reached a maximum intensity of 70 knots by 1200 UTC.

Forward motion of the hurricane increased to 18 knots on the 14th as the hurricane was steered by the mid- to upper-level trough to the west and a deep-layer-mean ridge to the east. Ismael made landfall near 0400 UTC 15 September in the vicinity of Topolobampo, Mexico.

The tropical cyclone weakened rapidly as the circulation moved over the Sierra Madre Mountains of northern Mexico, and it dissipated by 0000 UTC 16 September. However, considerable moisture from Ismael quickly spread over the southwestern U.S. and continued eastward through the mid-Atlantic states.


b. Meteorological Statistics

Best track positions and intensities were derived primarily from Dvorak technique estimates. Figures 2 (20K GIF) and 3 (22K 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. Table 2 lists ship reports with tropical storm force winds in the vicinity of Ismael.


c. Casualty and Damage Statistics

Newspapers reported 105 deaths and several more missing in association with Ismael. According to limited records of casualties along the west coast of Mexico available at the NHC, this makes Ismael the fifth deadliest eastern Pacific hurricane this century. Many of those who died were on fishing boats that encountered strong winds and high seas in the Gulf of California. The Associated Press reported thousands homeless as a result of the hurricane and about 5000 "rickety houses" destroyed. Some of the worst damage was in the village of Topolobampo, Mexico, located a few miles to the south of Los Mochis. Houses and telephone poles were knocked down in Los Mochis, but no deaths were reported there.


d. Forecast and Warning Critique

Since Ismael was a short-lived cyclone, there were only a limited number of official forecasts that were verified. During the time when Ismael was a tropical storm or hurricane, the average official track forecast errors were 57 (9 cases), 166 (7 cases), 311 (5 cases) and 445 (3 cases) n mi at 12, 24, 36 and 48 hours. These were two to three times as large as the NHC historical (1988-1994) average, but not atypical for northward moving storms.

In the early stages of Ismael, most track prediction models indicated a westward or northwestward motion away from land (for example, see Fig. 4 [68K GIF]). Only the GFDL model consistently predicted a northward motion toward Mexico. Unfortunately, confidence in the GFDL in the eastern Pacific was low due to experience with previous storms which were erroneously forecast to move northward by the GFDL. In 1994, the deep-layer BAM had the lowest forecast errors at most time periods. The NHC official forecasts for Ismael, even though large, were still less than the forecast errors from the deep-layer BAM at all time periods. Although it cannot easily be determined how many of the Mexican rawinsonde data were included in the NMC model initializations, forecasters received data from the closest upper-air stations of Socorro, Mazatlan and Empalme intermittently. Data from Socorro and Empalme were missing from NHC upper-air plots for 1200 UTC on 12-15 September and from Mazatlan at 0000 UTC on 13 September. No upper-air soundings were taken from the Baja peninsula. This lack of sufficient upper-air data likely contributed to poor initializations. Even with complete Mexican rawinsonde data, however, recurving storms near Baja are usually difficult to forecast, in part due to the sparsity of upper-air data between Mexico and Hawaii.

Intensity forecasts showed a slight negative bias (i.e., intensity was underestimated) on 13 September, and a positive bias (i.e., intensity was overestimated) thereafter. The positive bias was a result of the cyclone moving over land and weakening faster than forecast.

Usual uncertainty exists in determining the best track intensity when only satellite estimates are available. It is interesting to note from Figure 3 that the intensity estimates from the Air Force Global Weather Central never exceeded 45 knots.

Table 3 lists the watches and warnings issued by the Government of Mexico.


 
Table 1. Preliminary best track, Hurricane Ismael, 12-15 September 1995.
Date/Time
(UTC)
Position Pressure
(mb)
Wind Speed
(kt)
Stage
Lat. (°N)Lon. (°W)
12/180014.8106.7100930 Trop. Depression
13/000015.4107.1100535 Tropical Storm
060016.0107.4100240" "
120016.5107.7100045" "
180017.4108.099550" "
14/000018.3108.199060" "
060019.4108.298565Hurricane
120020.8108.598370"
180022.6108.898470"
15/000024.4109.098670"
060026.2109.199060 Tropical Storm
120028.3109.2100045" "
180030.5109.0100830 Trop. Depression
16/0000     Dissipated
 
14/120020.8108.598370 Minimum Pressure
Landfall:
Topolobampo, Mexico
15/040025.6109.198870Hurricane



 
Table 2. Ship encounters of 34-knot or higher winds, Hurricane Ismael, 1995.
Ship Call
Sign
Date
Mo/Da
Time UTCPositionWind (kt)
Dir/Speed
Pressure
(mb)
Lat°NLon°W
LAOQ29/13230021.1108.3 080/401006.5
OULL29/14000019.9106.0120/35 1005.1
LAOQ29/14020020.6107.6130/50 1005.0
LAOQ29/14050020.2107.0130/40 1003.0
3ECQ99/14050019.9106.6130/59 1003.0
ELC059/14060019.7106.1130/39 1007.0
ELOC59/14120020.4107.1150/36 1003.0
M/V CALIFORNIA9/14180022.2106.1 180/451008.0



 
Table 3. Watch and warning summary, Hurricane Ismael, September 1995.
Date/time
(UTC)
Action/Location
14/0300 Tropical Storm Warning issued from Manzanillo to Cabo Corrientes and for Las Islas Marias
14/0900 Tropical Storm Warning extended northward on the Mexican mainland to Los Mochis and for the Baja peninsula south of 25N
Hurricane Watch issued for the Mexican mainland from Mazatlan to Los Mochis and for the Baja peninsula south of 25N
14/1200 Hurricane Warning issued for the Baja peninsula from La Paz southward
14/1500 Hurricane Warning issued for the Baja peninsula south of 25N
14/1800 Hurricane Warning issued for the Mexican mainland from Mazatlan to Los Mochis
14/2100 Hurricane Warning extended northward on the Mexican mainland to Guaymas
15/0600 Tropical Storm Warning discontinued from Manzanillo to Mazatlan and for Las Islas Marias
15/1200 All watches and warning discontinued



Brian Maher
Jack Beven

Last updated January 4, 1999