Celia was a short-lived tropical storm
in the eastern North Pacific that briefly threatened southern
Baja California.
a. Synoptic History
The tropical wave from which Celia
apparently formed was first identified off the west coast of Africa
on 1 July. This wave moved westward at around 15 knots across the tropical Atlantic with no
development, entering the eastern Caribbean Sea on the 7th. It continued westward at low latitudes
over the Caribbean Sea, its development being precluded by strong vertical shear. On 11 July, the
wave crossed Central America and convective clouds began to show definite signs of organization to
the south of the Gulf of Tehuantepec on the 13th, prompting an 1800 UTC
Dvorak classification of
T1.0 by the Tropical Analysis and Forecast Branch (TAFB), with a
center fix near 8°N 98°W. Shortly
thereafter, the development trend ceased, as the cloud pattern became less-organized, resulting in the
system being declared "too weak to classify" by 14 July. There was little change as the cloud cluster
moved west-northwestward until the 16th, when the convective bands associated with the disturbance
became more curved and some locally heavy rains spread over the southern Mexico coastal area.
Development was rather rapid on the following day. Based partially on a ship report (see next section),
it is estimated that a 40-knot tropical storm had formed by 1200 UTC 17 July, and based on backward
extrapolation and satellite imagery, it is estimated that this system developed into a
tropical depression about six hours earlier,
around 130 n mi south of Manzanillo, Mexico (Table 1 and
Figure 1 [32K GIF]).
After becoming a tropical storm, Celia moved northwestward in the general direction of the southern
tip of Baja California (Cabo San Lucas). However, a mid- to upper-tropospheric anticyclone to the
north forced a more west-northwestward motion. Celia's center passed about 130 n mi south-southwest
of Cabo San Lucas early on the 18th. Later that day, the tropical cyclone became better-organized, and
reached its peak intensity of 50 knots. By 19 July, deep convection associated with Celia diminished. A
mid-level ridge along 30- 35 N latitude induced a mainly westward movement, and Celia gradually
spun down over cooler sea surface temperatures, weakening to a tropical depression on the 20th and
dissipating early on 21 July.
b. Meteorological Statistics
Figures 2 (15K GIF) and
3 (15K GIF) depict the curves of minimum central sea-level pressure and
maximum one-minute average "surface" (10 meters above ground level) wind speed, respectively, as a
function of time. Also plotted are the observations on which the curves are based, consisting of
Dvorak-technique estimates (from TAFB, the
Synoptic Analysis Branch, SAB,
and the U.S. Air Force
Global Weather Agency, AFGWC in the figures) using satellite imagery. Celia was upgraded directly
to a tropical storm based on a report from ship KGTI, of winds of 100/45 knots
at 18.5°N 104.6°W at 1200 UTC 17 July. Another ship, 4XGX, reported winds of
210/40 knots at 18.8°N 104.7°W and
130/50 knots at 19.4°N 105.6°W at 1200 UTC and 1700 UTC 17 July. These velocities appear to have
been estimated, and based on the subsequent evolution of the storm, the 45 and 50 knot speeds seem to
be slightly high. At 1200 UTC 18 July, another ship, VRUZ, reported 130/35 knot
winds at 22.9°N 109.0°W. That position is about 60 n mi east of Cabo San Lucas. No reports of tropical storm force
winds were received from Baja California.
c. Casualty and Damage Statistics
No casualties or damage are known to have occurred due to this storm.
d. Forecast and Warning Critique
Excluding the depression stage, the average official track forecast errors for Celia were 36 n mi at 12
hours, 67 n mi at 24 hours, 105 n mi at 36 hours, 141 n mi at 48 hours, and 120 n mi at 72 hours. These
errors are comparable to the most recent ten-year averages through 48 hours, but substantially lower
than the long-term average at 72 hours. There were, however, only four cases to verify at the latter
time. Intensity forecast errors were mostly less than 10 knots.
A tropical storm warning
was issued for extreme southern Baja California from La Paz southward at
0300 UTC 18 July. This warning was discontinued at 1500 UTC 18 July.
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