a. Synoptic History
A tropical disturbance gradually
became better organized during the middle of June off the southwest coast
of Mexico. The disturbance was possibly associated with a westward moving
tropical wave, although a lack of sufficient
upper-air data and significant cloudiness makes it difficult to accurately
track the wave from Central America into the
eastern Pacific Ocean.
Satellite imagery indicated increased banding features on 15 June, and the
"best track" (Fig. 1
[36K GIF] and Table 1) shows that the disturbance became
Tropical Depression Two-E at 1200 UTC on this date.
The depression began drifting generally toward the north at 5 to 7 knots while embedded
within weak steering currents. Deep convection increased near the
center, and the depression became
Tropical Storm Adolph at 0000 UTC 16 June.
At this time, Adolph was located over warm water and exhibited a well-defined upper-level
outflow pattern. The tropical cyclone
rapidly strengthened into a hurricane
by 0000 UTC 17 June when a banding type eye
appeared in satellite imagery. The hurricane gradually turned toward the northwest,
while the forward motion remained slow.
Rapid strengthening continued and Adolph is estimated to have reached maximum
sustained winds of 115 knots and a minimum pressure
of 948 mb at 0600 UTC 18 June based upon
satellite intensity estimates from analysts at the
Synoptic Analysis Branch
and the National Hurricane Center. The 3-hour averages of
objective intensity estimates peaked near this time when satellite imagery
indicated a small and distinct eye embedded within very cold cloud tops.
Adolph began weakening when the upper-level environment became less favorable and
when the cyclone moved over cooler water. On 19 June
the cyclone gradually turned toward the west and the forward motion slowed to less
than 5 knots. Adolph weakened to a tropical storm by 1200 UTC on this date, and to
a tropical depression by 1200 UTC on the following day. Adolph dissipated on 21 June
when the cyclone was centered about 300 n mi south-southwest of the
southernmost tip of Baja California. At this time Adolph was
characterized by a swirl of low clouds with no deep convection and
maximum winds of 20 knots.
b. Meteorological Statistics
The best track positions and intensities were derived solely from Dvorak technique
estimates. Figures 2 (23K GIF) and
3 (24K 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.
c. Casualty and Damage Statistics
The NHC has not received any reports of casualties or damage related to Adolph.
d. Forecast and Warning Critique
The government of Mexico issued a
tropical storm warning
and a hurricane watch
at 0300 UTC on the 17th from Punta Tejupan to Cabo
Corrientes when Adolph was about 250 n mi from the coast of Mexico
and moving northward near 6 knots. The watch and warning were
discontinued at 1500 UTC on the 18th, when it was determined that
the cyclone was going to move northwestward away from the mainland.
There were sixteen official forecasts verified during the time
when Adolph was of tropical storm stage. The mean official track
forecast errors of 33, 64, 91, 142 and 250 n mi at 12, 24, 36, 48
and 72 hours respectively were close to the long-term averages from
1988 through 1994, except at 72 hours which were somewhat larger.
The forecast rates of strengthening and weakening were less
than the observed rates. There were two 65 knot under-forecasts at
the 48 hour period which contributed to a large negative bias
during the developing stage. During these early stages, Adolph was
over warm water and exhibited an impressive outflow pattern in
satellite imagery, but only a little strengthening was forecast
because of the forecasters' reliance on the NMC Aviation Model
which incorrectly indicated strong upper-level westerlies moving
over the cyclone.