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Preliminary Report
Hurricane Tanya
27 October-1 November 1995

Richard J. Pasch
National Hurricane Center
1 February 1996

Hurricane Allison
Tropical Storm Barry
Tropical Storm Chantal
Tropical Storm Dean
Hurricane Erin
Tropical Depression Six
Hurricane Felix
Tropical Storm Gabrielle
Hurricane Humberto
Hurricane Iris
Tropical Storm Jerry
Tropical Storm Karen
Hurricane Luis
Tropical Depression Fourteen
Hurricane Marilyn
Hurricane Noel
Hurricane Opal
Tropical Storm Pablo
Hurricane Roxanne
Tropical Storm Sebastien
Hurricane Tanya

[1995 Atlantic Hurricane Season]

Tanya caused gale force winds over the Azores, while losing its tropical characteristics.

a. Synoptic History

Tanya originated from a tropical wave that, based on extrapolation, moved off the west coast of Africa in mid-October. This wave followed one that spawned Tropical Storm Sebastien, and was not easily identifiable as a cloud mass on satellite pictures until 20 October, when it neared 40°W longitude in the tropical Atlantic. The wave moved slowly westward for a few days. By 24 October, cloudiness associated with the wave merged with an area of convection to the east and northeast of Tropical Depression Sebastien. This weather was partly associated with an upper-level cyclone that was producing shearing winds over Sebastien, causing its demise. At 1800 UTC on the 25th, a low cloud swirl was evident in the vicinity of 22°N 60°W. However, this system was barely classifiable by the Dvorak technique since deep convection was not very close to the center. The low-cloud swirl became more pronounced on satellite images on the 26th. By 0000 UTC 27 October, surface observations indicated a definite closed surface circulation, and the tropical depression stage of Tanya is initiated at this time in the post-analysis best track (Table 1 and Fig. 1 [63K GIF]).

The movement of the tropical cyclone was controlled mainly by two factors: shortwaves in the midlatitude westerlies and the upper-level cyclone in Tanya's vicinity. Initially the cyclone moved northeastward, in response to an approaching shortwave trough. However, due to the effect of the upper cyclone, Tanya turned more eastward and slowed.

Because of the influence of the upper-level cyclone, the development of Tanya was not like that of a typical tropical cyclone in the deep tropics. On the 27th and 28th, the system had some subtropical characteristics, i.e. a large comma-shaped cloud band and strongest winds well removed from the center. Nonetheless, Tanya's winds increased to tropical storm force by 1200 UTC on the 27th and gradual strengthening continued thereafter. Convection developed closer to the center by 1800 UTC on the 28th, and on the following day the cloud pattern was more symmetrical about the center. Tanya reached hurricane strength around 1200 UTC on the 29th, when a small eye was observed in the middle of the central dense overcast.

While Tanya was strengthening into a hurricane, its motion was cyclonic along roughly a half-circular path, again due to the adjacent upper low. This movement continued into the 29th, when a strong eastward-moving mid-tropospheric trough over the western Atlantic, and associated cold front near Bermuda, began to influence the track of the hurricane. Tanya turned north- northeastward on the 30th, and east-northeastward later that same day. Early on the 31st, while still embedded in a narrow wedge of warmer air between cooler air masses over the western and eastern Atlantic, the system acquired peak intensity of 75-knot winds with a 972 mb central pressure.

On the 1st of November, Tanya veered to the east and weakened to a tropical storm - headed in the general direction of the Azores. As the storm neared those islands, the movement became more northeasterly, taking the center just to the north of the Azores. Tanya was becoming extratropical as it passed near the Azores. The extratropical cyclone turned north-northeastward, then northward, and was absorbed into a larger low pressure system over the north Atlantic by 0600 3 November.

b. Meteorological Statistics

The post-analysis best track intensities are listed in Table 1 and displayed in Figs. 2 and 3 (56K GIF), which show the estimated minimum central pressure and maximum one-minute wind speed, respectively, versus time. These intensity estimates were derived mainly from analyses of satellite images, using the Dvorak technique, performed by meteorologists at the Synoptic Analysis Branch (SAB), the Tropical Analysis and Forecast Branch (TAFB; formerly the Tropical Satellite Analysis and Forecast unit, TSAF, as in the figures), and at the Air Force Global Weather Central (AFGWC).

There were some surface observations from the Azores of sustained gale force winds. Lajes Air Base on Terceira measured sustained winds of 34 knots at 2255 UTC with gusts to 59 knots at 2343 UTC on the 1st. Santa Maria Island reported sustained winds of 39 knots at 2300 UTC on the 1st, with gusts to 50 knots at 0200 UTC on the 2nd. Lowest pressure observed in the Azores was 973.5 mb at Horta on the island of Faial.

Table 2 is a listing of ship reports of tropical storm force wind speeds associated with Tanya. One ship, with call sign GBSA, had the misfortune of being near the center of Tanya twice: on the 29th, when Tanya was a hurricane; and on the 2nd, when Tanya was an extratropical storm.

c. Casualty and Damage Statistics

Although strong winds likely had some impact on the Azores and ships that were affected by Tanya, no reports of casualties or damage have been received at the NHC.

d. Forecast and Warning Critique

At 12, 24, 36, 48, and 72 hours, the mean official forecast errors for Tanya were 65, 121, 166, 237, and 357 n mi, respectively. These are 20 to 30 per cent larger than the most recent ten-year average errors. This is not too surprising, since Tanya was a relatively high-latitude tropical cyclone, and track forecasts for such systems are typically not as good as those for cyclones in the deep tropics. The average official forecast error was comparable to, or lower than, the average error of any of the available objective track prediction models.

Beginning at 0300 UTC 1 November, a statement was included in the advisories that tropical storm conditions were expected to spread over the Azores within 24 hours. This turned out to be roughly correct, since sustained winds of at least 34 knots occurred at these islands around 0000 UTC on the 2nd. However, Tanya is estimated to have lost tropical characteristics by that time.

Table 1. Post-analysis best track, Hurricane Tanya, 27 October - 1 November, 1995.
Position Pressure
Wind Speed
Lat. (°N)Lon. (°W)
27/000024.659.2100430 Tropical Depression
060025.358.6100230" "
120026.257.9100135 Tropical Storm
180027.157.199840" "
28/000027.256.699745" "
060027.356.299645" "
120027.255.799550" "
180027.554.799255" "
29/000028.454.299060" "
060029.654.298760" "
120037.435.497460Tropical Storm
180037.731.897255" "
02/000039.228.297055 Extratropical
0600     Absorbed by Larger Extratropical Cyclone
31/060035.448.397275 Minimum Pressure (as a tropical cyclone)

Table 2. Ship encounters of 34 knots or
higher associated with Hurricane Tanya.
Ship Call
Position Wind (kt)
VRUC410/28030028.952.6 100/381015.0
VRUC410/28090028.651.5110/44 1014.0
VRUC410/28120028.351.1130/37 1016.0
GBSA10/29090030.055.5020/60 991.2
GBSA10/29120030.454.8220/45 985.5
GBSA10/29150030.854.1160/52 995.3
GBSA10/29180031.153.2130/42 998.1
9HOO310/30210032.547.1170/40 1013.0
WMLH10/31000039.464.0300/35 1020.0
9HOO310/31000031.947.4160/40 1012.0
C6MD611/01120034.834.3250/50 995.3
ELSE411/01120034.532.5250/35 998.5
FNZP11/01120037.435.0160/40 976.2
FNOU11/01120034.138.5290/45 1003.3
4QVV11/01120035.533.1220/40 993.7
C6KB311/01120033.142.0310/35 1011.0
ELSE411/01180033.832.9270/45 999.5
FNOU11/01180035.337.0280/40 999.2
Y5ET11/01180036.228.9210/35 992.5
SHIP11/01180034.327.9210/35 997.5
P3TQ611/01180033.726.5210/40 998.5

Brian Maher
Jack Beven

Last updated January 8, 1999