a. Synoptic History
Tropical Storm Dean developed from a
broad quasi-stationary middle-level trough extending from the northeastern
Gulf of Mexico through Florida. On the 27th of July, a weak
cyclonic circulation was indicated by buoy reports in the
eastern Gulf of Mexico accompanied by surface pressure falls
of about 2.5 mb in 24 hours. At that time, satellite images
showed that the thunderstorm activity was disorganized but the
upper-level outflow was beginning to become established. On
the 28th, animation of high resolution visible satellite
images clearly showed a low-level cyclonic rotation. Based on
that information and on surface reports, it is estimated that
Four formed about 300 n mi southeast of New Orleans at 1800 UTC July 28.
A reconnaissance plane was dispatched to the area and located a circulation
of 1008 mb minimum pressure. The maximum flight-level (1500 ft) wind was 32 knots. The
depression moved slowly toward the west to west-northwest
around a well-established mid-level high pressure ridge
located over the central U.S., with no significant change in
strength. The depression was under continuous reconnaissance
surveillance and, during the time between the last
at 1712 UTC 30 July of mission number 5 and the first fix of mission
number 6 at 2142 UTC 30 July, the pressure dropped from 1005
mb to 999 mb and the flight-level (1500 ft) winds increased
from 40 to 50 knots. Using this data, it is estimated that
the depression became Tropical Storm Dean at 1800 UTC 30 July
about 60 n mi from the upper Texas coast. The center of Dean
crossed the coast near Freeport, Texas a few hours later.
have occasionally intensified just prior to making landfall in that area.
Dean weakened to tropical depression status shortly after
landfall and continued on a northwestward track through Texas.
The depression became nearly stationary for about 24 to 36
hours over the northwest portion of the state producing heavy
rainfall. It dissipated at 0000 UTC August 3 as it merged with a frontal zone.
Dean's track is shown in Fig. 1 (43K GIF).
Table 1 is a listing, at six-hour intervals, of the
position, estimated minimum central pressure and maximum 1-minute surface wind speed.
b. Meteorological Statistics
The best track pressure and wind curves as a function of time shown in
Figures 2 and 3 (41K GIF)
are based on reconnaissance aircraft data,
satellite intensity estimates
from the National Hurricane Center, the
Satellite Analysis Branch (SAB)
and the Air Force Global Weather Central (AFGWC).
There were no reports of tropical storm force winds (1-min sustained) from
surface land stations. The highest observed wind was a 44-knot
gust reported by Galveston Scholes Field at 2115 UTC 30
July. The storm tide rose and covered the road along highway
82 between Johnsons Bayou and Holly Beach in Cameron Parish,
Louisiana. Minor storm surge flooding of highway 87 occurred on the 30th.
There were two tornadoes associated with Dean. The
first occurred in Galveston County at High Island around 2330
UTC and the second touched down just southeast of Anahua near
0300 UTC. Table 2 includes some of the most significant
rainfall totals received so far associated with Dean.
c. Casualty and Damage Statistics
There were no reports of injuries or deaths associated
with Dean. However, rainfall was a problem causing near
$500,000 in damage. Evacuation of 20 families was necessary
in Chambers County due to rainfall flooding. Data were
provided by local weather service forecast offices.
d. Forecast and Warning Critique
Since the tropical cyclone was forecast to reach
tropical storm strength before landfall, a
warning was issued for the Gulf of Mexico coast from
Intracoastal City, Louisiana to Corpus Christi, Texas at 0300
UTC 30 July. The warning was issued 23 hours before landfall
and discontinued at 0300 UTC 31 July.
Dean was a tropical storm for less than 12 hours, so
there were practically no cases from which to verify official forecasts.