a. Synoptic History
Georgette's origin may be related to a tropical wave
which appeared in the far eastern tropical
Pacific Ocean on 4 August. The associated area of disturbed weather moved slowly westward. By the 9th,
satellite images showed evidence of a low-level circulation located six hundred nautical miles south of
Manzanillo, Mexico. On the 11th, as banding features developed, the cloudiness became separated from the
intertropical convergence zone clouds and the system was identified as
Tropical Depression Eight-E.
The tropical cyclone moved on west-northwest
to northwestward track throughout its existence (see Fig.1 [23K GIF]),
tracing out the periphery of a subtropical high pressure ridge. This track kept the center
well offshore from the coast of Mexico. The forward speed was mostly in the 10- to 12-knot range, until near
dissipation on the 17th, when the motion became a slow westward drift.
Intensification was fairly steady as shown by the pressure and wind curves in
Figs. 2 (16K GIF)
and 3 (16K GIF). Georgette became a
tropical storm late on the 11th and a
hurricane early on the 13th based
on banding features. An eye formed on the 13th,
measuring 35 nautical mile in diameter. This is indicative of a large storm.
Based on the eye and banding features, satellite intensity estimates reached
100 knots on the 14th. Cloud tops soon started to warm and weakening continued until
dissipation on the 17th. There was a small convective burst on the 15th, when convection had been
decreasing, but this did not appear to significantly affect the weakening trend.
b. Meteorological statistics.
Figs. 2 and
3 show plots of the satellite
Dvorak intensity estimates, as well as the best-track
pressure and wind curves. Subjective Dvorak estimates were provided by the U.S.
Air Force Weather Agency
(AFGWC), the Tropical Analysis and Forecast Branch
(TAFB) of the Tropical Prediction Center, NWS and the
Synoptic Analysis Branch (SAB) of
NESDIS. Objective Dvorak intensities
reached a current intensity number of 5.6 for a three-hour average and a one-hour value of 6.0 which corresponds to
115 knots. This is somewhat higher than the subjective estimates plotted in
Fig. 3.
c. Casualty and damage statistics
There are no known casualties or damages in connection with this hurricane.
d. Forecast and warning critique.
There were no watches or warnings issued.
The average official track forecast errors ranged from 87 nautical miles at 24 hours (17 cases)
to 149 nautical miles at 48 hours to 194 nautical miles at 72 hours (9 cases). These average errors are near or
slightly above the previous ten-year official averages.
Even though the track of Georgette was rather straight and steady, the official errors exhibited
a right bias for the first few forecasts and a left bias for the next several forecasts...and finally achieved a
near-zero bias for the last several forecasts. The GFDL
model first had a right bias and then a left bias and the LBAR also had a left bias for many
of the early forecasts. The UKMET model did not show much bias and also
had lower errors than the official forecast for the 12- through 48-hour forecasts.
The official intensity errors were mostly negative, primarily due to the failure to forecast the
steady intensification to 100 knots.
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