Using EPS to assess downstream uncertain-ties when TC´s occuring - An example.

Outlines:

• In which way can we use EPS to obtain a qualitative impression of the uncertainties regarding TC´s and their extratropical stage?

• Can this aid us in early decision making when we know the operation criteria limits?

• Can this give example give an approach towards a more generel methodology?

Tropical Cyclone impact on scores

Container vessel Marchen Maersk sailed from Los

Angeles to Yokohama 2009 October 7th-21th:

1) Avoid Heavy Weather Damage:2) Most economic route3) Fastest route

Fin stabilizer

Millions of USD lost…

Missing Fin stabilizers

Limit of sig. waves for this voyage about 6m.

Weather routeing request:• Requested service: Weather routeing• Company name: A.P.Møller Mærsk• Ship name: Marchen Mærsk• Imo no: 9359014• Call sign: OUIY2• Inmarsat no: +870 763 747 691• E_mail ship: mbxmarchen@maersk.com• Dept port: Los Angeles• Dept country: USA• Etd date (utc): 06.Oct.2009.• Etd hour (utc): 2359• Arr port: Yokohama• Arr country: Japan• Eta date(utc): 21.Oct.2009.• Eta hour(utc): 1600• Service/eco speed: Service speed is 25kn• Gmt: 3m Expected• Displacement: 101000mt• Fin Stabilizer yes/no: No• Remarks/requirements: I expect to run with required speed in order to be• as economical as possible.

Routes: RL=5030nm GC=4750nm GC via Bering Sea (Unimak Passage/Attu Island)=4850nm

TC activity enroute: 1) Typhoon ”Melor” (a reality by time of departure) 2) Possible developments east of the Philippines

1st advice (6/10): GC via Unimak passage to north of Attu Island for Yokohama.

• Motivation: Passing safe north of ”Melor” the 12th and later getting

mainly north of the lowtrack.

• Synopsis main feature: …”Typhoon ”Melor” was the 6th/06:00 located at

23.9n/130.9e and is currently moving n-wards about 15kt, later ne- to e-wards becoming extratropical during the 9th th and most likely taking a track along 48-50n without causing you troubles..”

Iteration 7th/00z+24hr = 8th/00z +48hr = 09/00z

+72hr = 10/00z +96hr = 11/00z

Daily evaluation of the forecasts

• Checking significant changes in the forecasts from day to day

• Forecasts from the 8th almost similar to the ones from the 7th, except for…:

• A tropical depression is detected east of the Philippines

New ”Dangerous” forecast valid 15th/12z!! Deterministic run based on Iteration 9th/00z

EPS – Significant wave – Valid 15/12:00Z

+6m

Forecast base time 9th/00z 35-65%

Example (95-100%)

Recently detected TD 23w (Oct 8th), later TS ”Nepartak”, viewed in ECMWF´s ”Strike

Probability Map” October 9th/00z

Preliminary route alternate:Deviation point 51n/150w

+6m (35-65%)

Dangerous area 15th of oct.

Vessel pos 9th of oct.

2nd advice (9/10): Now GC via 51n/150w, thence until further GC south of the Aleutians via

50n/175e for Yokohama.

• Motivation: Waiting until apprx. 150w (11th/AM where the situation

hopefully has become less unsettled, then probably deviating just south of the Aleutians due to a long-term forecasted, northgoing strong gale- or storm low just south Kamchatka during the 14-15th – with risk of + 6m seas.

• Synopsis main feature: ..” Former typhoon "Melor” became officially declared

extratropical the 09/06:00 at 44n/150e and now continues e- to ene-wards along 49-50n - forecasted the 12th/12:00 near 50n/157w and just after passing south of you. Revert- ing with further details about the possible strong low south of Kamchatka in our next update, by the latest October the 12th.

Iteration 9th/00+24hr = 12/00z +48rs = 13/00z

+72hr = 14/00z +108hr = 15/12z

Ex-”Melor”

l

Ex-”Melor”

ECMWF Cyclone Tracker / SPM starting up when a TD is detected. Nepartak 9th-11th:

Wave Epsgram from Oct 10th/00z

EPS members suggest more northerly track

”Nepartak” life cycle October 8th-14th close to the 11th/00z iteration

TD ”23W” first detected 8th/12:00

Upgraded to TS ”Nepartak” the 9th

Surface map the 15th/12:00 – iteration 11th/00z far better than the 9th/00z run

3rd advice (11/10): Now proceed GC via Unimak passage to north of Attu Island for

Yokohama.• Motivation: • The recent uncertainties regarding seas about 6m via

Unimak-Attu route, caused by tropical cyclone activity south of Japan (Nepartak), has now reduced significantly and it seems quite confident that "Nepartak" will pass safe south of the vessel.

• Synopsis main feature: ..” Former typhoon "Melor", now an ordinary extratropical

low near 49n/162w continues e- later- ese-wards, passing just south of you the 12th/AM, while ene-going (ex-) ”Nepartak" passes well south of you along 42-45n the 15th/PM (please note that there is a still risk of a slight more northerly track)”..

Summary: In which way can we use EPS to obtain a qualitative impression of the

uncertainties regarding TC´s and their extratropical stage? Compare various plots of EPS including spatial- and time related aspects of the development.

Can this aid us in early decision making, when we know the operation

criteria limits? Setting up a specific deadline to take action in order for a given parameter not to be exceeded or event to take place (binary=yes/no) will help us doing this (for example take action when probability > 35% after T+xx hrs)

Can this give example give an approach towards a more generel methodology? Any parameter can be involved, for example temp>30 deg, 10m winds>25 m/s, precipitation>20mm/6hrs. Knowledge about the models ability to predict the phenonomen must be known.