Observed and Forecast Tracks: Northern Hemisphere 2011

Click on the name of the tropical cyclone to see a chart of the observed track and forecast tracks from the Met Office global model. Verification statistics on each tropical cyclone are available upon request from [email protected]. At the end of the season a verification report on the performance of the Met Office global model will be published.

North-west Pacific
Name & ID Start & end dates 1-/10-minute MSW Comments on Met Office global model forecasts
01W 02-03 April 30/- knots 01W did not attain tropical storm status and no forecasts were verified.
02W 05-06 April 30/- knots 02W did not attain tropical storm status and no forecasts were verified.
Aere (03W) 06-11 May 50/45 knots Track forecast errors were mixed compared to last season's values, but skill was high at longer lead times. The landfall on Luzon was fairly well predicted.
Songda (04W) 20-29 May 140/105 knots Track forecast errors were mostly below last season's average. There was a left of track and slow bias resulting a slightly late prediction of recurvature and extratropical transition. However, skill scores against CLIPER were high.
Sarika (05W) 09-11 June 35/40 knots Sarika was only briefly a tropical storm
Haima (06W) 16-24 June 35/40 knots There was a slight right-of-track bias early on, but overall track forecast errors were below last season's average and skill scores were very high.
Meari (07W) 21-27 June 60/60 knots Track forecast errors were very low and skill scores high for this storm. There was a slight slow bias at longer lead times.
Ma-on (08W)    11-24 July   115/95 knots Ma-on was a long-lived typhoon with several changes in direction. On the whole these changes in direction were well predicted by the model. The track errors were near to last season's average. There was a slow and left-of-track bias overall, but skill scores against CLIPER were high.
Tokage (09W) 15-16 July 30/35 knots Tokage was designated a tropical storm by JMA, but not JTWC. It was short-lived and no forecasts were verified.
Nock-ten (10W) 24-30 July 65/50 knots The track of Nock-ten was very well predicted with low track forecast errors. Skill scores against CLIPER were also high.
Muifa (11W) 24 July-08 August

140/95 knots

Forecast track errors were above last season's average, although skill scores were positive. The model turned Muifa too sharply westwards towards Taiwan.
Merbok (12W) 03-09 August 80/55 knots The model erroneously stalled Merbok resulting in some large timing errors in the prediction of recurvature. Hence, track forecast errors were generally large.
13W 10-12 August 30/30 knots 13W did not reach tropical storm strength and no forecasts were verified.
Nanmadol (14W) 22-31 August 135/105 knots Although the model had a right-of-track bias, its forecasts for Nanmadol were much better than some other models in predicting a track close to the Philippines and towards Taiwan. Hence, track errors were below last season's average.
Talas (15W) 25 August-05 September 55/65 knots The majority of forecast tracks for Talas were good resulting in track forecast errors below last season's average.
Noru (16W) 03-06 September 45/40 knots Track forecast errors were below average for this storm
Kulap (17W) 07-10 September 45/35 knots Kulap was only briefly a tropical storm and few forecasts were verified.
Roke (18W) 11-22 September 115/95 knots Roke's rapid acceleration across Japan was well predicted close to the event, but earlier forecasts kept the typhoon slow-moving south of Japan. Due to the large distance travelled by the typhoon as it raced across Japan, some of the forecast errors from earlier forecasts were very large. Overall, track forecast errors were above last season's average.
Sonca (19W) 14-20 September 85/70 knots Track forecasts for Sonca were mostly good and errors were below last season's average.
Nesat (20W) 23-30 September 105/80 knots A couple of early forecasts erroneously predicted a north-westward turn resulting in large longer lead time errors. However, track errors at shorter lead times were low.
Haitang (21W) 24-27 September 35/35 knots Track forecast errors were low for Haitang.
Nalgae (22W) 27 September-05 October 130/95 knots Forecast track errors were below average for this storm and skill scores against CLIPER were high.
Banyan (23W) 10-14 October 35/35 knots Despite persisting for several days as a tropical depression, Banyan was only briefly a tropical storm and just one forecast was verified.
24W 07-08 November 30/- knots 24W was a tropical depression and no forecasts were verified.
25W 04-05 December 30/- knots 25W was a tropical depression and no forecasts were verified.
26W 12-13 December 30/30 knots 26W was a tropical depression and no forecasts were verified.
Washi (27W) 13-19 December 55/40knots Track forecast errors were below last season's average for this late season storm.

North-West Pacific observed tracks in 2011
Tropical cyclone names

North-east Pacific
Name & ID Start & end dates 1-minute MSW Comments on Met Office global model forecasts
Adrian (01E) 07-12 June 120/- knots Track forecast errors were low and skill scores high with just a slight slow bias for this hurricane.
Beatriz (02E) 19-22 June 75/- knots Forecast tracks were too far to the left resulting in a failure to predict the proximity of the track to land.
Calvin (03E) 07-10 July 70 knots Calvin was relatively short lived. Track forecast errors were low and skill scores high.
Dora (04E) 18-24 July 135 knots The direction and speed of motion of Dora were very well predicted with only slight deviations at longer lead times. Forecast errors were low and skill scores high.
Eugene (05E) 31 July-06 August 115 knots Eugene was a straight-running storm which was well predicted in nearly all forecasts. Hence, track forecast errors were very low.
Fernanda (06E) 16-20 August 55 knots Track forecast errors were low and skill scores high for this storm.
Greg (07E) 16-21 August 75 knots Track forecast errors were slightly above last season's average, but were still low.
08E 31 August-01 September 30 knots 08E did not reach tropical storm strength and no forecasts were verified.
Hilary (09E) 21-30 September 125 knots Track forecasts for Hilary were generally good and forecast errors below last season's average.
Irwin (11E) 06-17 October 80 knots Track forecast errors for Irwin were near to last season's average. The turn back eastwards early in its life was well predict
Jova (10E) 06-13 October 110 knots Track forecast errors were near to last season's average. The hurricane's changes in direction were generally well handled, although the final acceleration northwards near landfall was not.
12E 12-13 October 30 knots 12E did not reach tropical storm status and no forecasts were verified.
Kenneth (13E) 19-25 November 125 knots Kenneth was the latest season major hurricane ever recorded in this region. Track forecasts were very good with low errors and high skill scores. The formation of the hurricane was also well predicted.
Central North Pacific
Name & ID Start & end dates 1-minute MSW Comments on Met Office global model forecasts

North-East and Central North Pacific observed tracks in 2011

Tropical cyclone names

North Atlantic
Name & ID Start & end dates 1-minute MSW Comments on Met Office global model forecasts
Arlene (01L) 28 June-01 July 55/- knots The few forecasts which were verified had track errors below last season's average.
Bret (02L) 17-22 July 55 knots The track of Bret was well predicted. Track errors were low and skill scores high.
Cindy (03L) 20-22 July 50 knots Cindy was a tropical storm for less than two days, but in this time track forecasts were very good.
Don (04L) 27-30 July 45 knots Don was a tropical storm for a couple of days and in this time track forecasts and the location of landfall were very well predicted.
Emily (05L)   02-07 August 45 knots There was a fast bias in forecasts for Emily resulting in track forecast errors above last season's average.
Franklin (06L) 12-14 August 40 knots Franklin was short-lived and only one forecast was verified.
Gert (07L) 14-16 August   50 knots The few forecasts for this storm that could be verified had a left-of-track bias.
Harvey (08L) 19-22 August 50 knots Harvey was short-lived as a tropical storm and only a few forecasts were verified.
Irene (09L) 20-29 August 105 knots Early forecasts had a left-of-track bias and later forecasts a slow bias at longer lead times. Overall, this resulted in short lead time track forecast errors being near last season's average, but longer lead time errors being higher than average. Skill scores against CLIPER were positive, but not high.
10L 25-27 August 30 knots 10L did not reach tropical storm strength and no forecasts were verified.
Jose (11L) 28-29 August 40 knots Jose was a short-lived storm and no forecasts were verified.
Katia (12L) 29 August-10 September 115 knots Track forecast errors were low and skill scores against CLIPER high for short lead times (up to 72 hours). However, longer lead time forecasts had a left-of-track and slow bias resulting in higher than average track forecast errors. The model handled the extra-tropical transition and subsequent impact on the UK well.
Unnamed 01-02 September 40 knots This short-lived storm was added to the list in post-season reanalysis
Lee (13L) 02-05 September 50 knots Lee was well predicted by the model - track forecast errors low and skill scores high.
Maria (14L) 06-16 September 70 knots Track forecast errors were near to average at short lead times and above average at longer lead times due to a left-of-track bias. Skill scores against CLIPER were high.
Nate (15L) 07-12 September 60 knots Track forecast errors were near to last season's average. Forecast tracks were a little too far north, but skill scores were high.
Ophelia (16L) 21 September-03 October 120 knots At short lead times track forecast errors were low, but at longer lead times they were high. This was primarily due to the failure to predict the period when Ophelia degenerated and was quasi-stationary midway through its life. The northward acceleration during extratropical transition was generally well handled.
Philippe (17L) 24 September-09 October 80 knots Early forecasts turned Philippe northwards too quickly. Some later forecasts also predicted extratropical transition too soon. However, the main change from a westward to eastward track was fairly well handled. Track forecast errors were mostly above last season's average.
Rina (18L) 23-28 October 95 knots The track of Rina was well forecast and forecast errors were below last season's average.
Sean (19L) 08-12 November 55 knots Track forecast errors were low and skill scores high for this storm

North Atlantic observed tracks in 2011

Tropical cyclone names

North Indian
(forecast track charts for Global and South Asia models shown)
Name & ID Start & end dates 1-/10-minute MSW Comments on Met Office global model forecasts
01A 11-12 June 35/30 knots 01A only briefly reached tropical storm status according to JTWC.
02B 19 October 35/30 knots 02B only briefly reached tropical storm status according to JTWC.
Keila (03A) 02-03 November 35/35 knots Keila was a short-lived storm and only one 12-hour forecast was verified.
04A 07-09 November 35/- knots 04A was short-lived as a storm and the few forecast verified had higher than average track forecast errors.
05A 26-30 November 35/30 knots Track forecast errors were low for this storm and skill scores against CLIPER, particularly at longer lead times, were high.
Thane (06B) 25-30 December 80/65 knots Track forecast errors were very low and skill scores very high for this storm. All but the first forecast predicted the landfall location and timing very well.

North Indian observed tracks in 2011

Tropical cyclone names


Note on estimated wind speeds

1-minute MSW: Maximum sustained wind (knots) averaged over 1 minute (JTWC Hawaii, NHC Miami, CPHC Hawaii)

10-minute MSW: Maximum sustained wind (knots) averaged over 10 minutes (JMA Japan, IMD New Delhi)
Note: Although 1-minute average winds should be stronger than 10-minute average, this may not be the case here since estimates are obtained from different warning centres.