5 Tropical Revolving Storms 5.1 Introduction Introduction A Tropical Revolving Storm is a cyclonic disturbance originating in the tropics. It involves strong convection, frequently frequently extending from the surface to the tropopause. Characteristics: smaller size than temperate depressions; nearly circular isobars no fronts very steep pressure gradient great intensity; • • • • •
World Meteorological Organisation nomenclature nomenclature is based on wind speed: Description Wind speed Beaufort force Tropical depression <= 33 kts <= 7 Moderate tropical storm 34 - 47 kts 8 and 9 Severe tropical storm 48 - 63 kts 10 and 11 Hurricane or synonym >64 kts 12 Synonyms: Cyclone Indian Ocean. Hurricane North Atlantic, Atlantic, Caribbean, Caribbean, central and east east North Pacific, Pacific, and South Pacific. Pacific. Typhoon Western North Pacific and South China Sea. Extreme values of elements: Pressure 870 hPa Rainfall 95 mm/h Storm surge 13 m. (Sea level rise due to low atmospheric pressure, wind and shallow water) Wind speed 185 kts Wave height 34 metres Size Approximate radius of gale force winds, minimum 30 NM, maximum 600 NM Duration 31 days Tropical storms are potentially capable of overwhelming the largest and most seaworthy vessels and should be avoided if at all possible. The area of greatest danger is the eye where sea waves are both extremely high and approach from all directions. 5.2 Development of Tropical Revolving Storms 5.2.1 Conditions for formation Considerable energy is required for the formation and development of a tropical revolving storm. This is derived from energy contained in water vapour and particularly latent heat released by condensation. The following conditions are required: Sea temperature greater than 26°C over a large area raising air temperature and humidity. Atmospheric instability due to high Environment Lapse Rate. Instability accentuated accentuated by high humidity increasing Saturated Adiabatic Lapse Rate. Latitude greater than 5° where the Coriolis Force is sufficient to provide vorticity, cyclonic circulation. Low wind shear (change of wind speed with altitude) in the troposhere permitting permitting vertical development. Conditions permitting divergence divergence of airflow at altitude, removing air from the area and reducing atmospheric pressure. A tropical disturbance to initiate the process. This is likely to be convection associated with an easterly wave, the InterTropical Convergence Zone. !
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5.2.2 Tropical Revolving Storm areas and seasons Areas of tropical revolving storm genesis are in approximately 10° latitude in the warmest areas of the oceans. These, with months of highest occurrence and average annual frequency, are: North Atlantic August - October 9 North Indian Ocean May - June, October - November 6 North Pacific West July - October 26 North Pacific East August - September 13 South Atlantic One Tropical Revolving Storm has been recorded, in March 2004. South Indian Ocean West January - March 8 South Indian Ocean East January - March 10 South Pacific West January - March 6 Global total 79 • • • • • • • •
Average monthly frequency of Tropical Revolving Storms. Area North Atlantic Western North Pacific Eastern North Pacific Western North Indian Ocean Eastern North Indian Ocean South Atlantic Western South Indian Ocean Eastern South Indian Ocean Western South Pacific
J
F
M
A
0.4
0.2
0.3
0.4
0.1 0.1 1.3 0.3 0.7
1.7 0.2 0.4
0.2 <0.1 1.2 0.2 0.6
0.1 0.2 0.6 0.1 0.2
M 0.1 0.7 0.1 0.2 0.5
J 0.4 1.0 0.8 0.3 0.6
J 0.5 3.2 0.7 0.1 0.8
A 1.5 4.2 1.0 0.6
S 2.6 4.6 1.9 0.1 0.7
O 1.9 3.2 1.0 0.2 0.9
N 0.5 1.7 0.1 .3 1.0
0.2 0.1
D 1.2 0.1 0.4 0.1 0.1 0.3
5.2.3 Tropical Revolving Storm development Considerable research continues into the details of tropical storm formation. Broadly the sequence is: Preconditions exist. These do not inevitably lead to storm formation, but are the minimum criteria required. Reduced pressure leads to airflow toward the centre. Coriolis effect produces cyclonic motion. Convection and convergence produce ascending airflow at the centre. Adiabatic cooling of ascending air leads to condensation. Condensation releases latent heat, which accentuates convection. Divergence at altitude permits further ascent and convergence at the surface. The system intensifies and acquires the structure of a Tropical Revolving Storm. •
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5.2.4 Structure of a Tropical Revolving Storm Elements of the structure: Outer convective band of cumulus cloud. Annular zone of descending air clear of cloud. Inner convective band of deep cumulus, and cumulonimbus extending to the tropopause, in spiral bands moving toward the centre. Eye Wall of high velocity wind moving parallel to the isobars and ascending rapidly. Eye, descending air warming adiabatically and cloud free. Horizontal wind speed very low. Canopy of cirrus clouds at the troposphere in the divergent outflow, some of which descends in the annular zone. • • •
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5.2.5 Movement Tropical revolving storms move approximately with the flow of air in the troposphere in their vicinity. A high proportion of storms move around the oceanic anticyclone into higher latitudes. Others move westward with a degree of poleward movement. Movement may be highly erratic within the broad pattern. Speed varies from approximately 10 kts near the equator to 25 knots in higher latitudes. 5.2.6 Decay Tropical Revolving Storms endure as long as conditions lie within the necessary parameters. Decay occurs when the energy required for sustained activity is no longer available. This occurs when the storm moves over an area where temperature and humidity are reduced. This may be a land surface in the tropics, or a sea surface in the tropics or higher latitudes where temperatures are lower. A Tropical Revolving Storm may cross a landmass, decreasing in intensity, then regenerate over a warm sea surface again. Tropical Revolving Storms cross the Central American isthmus, the Philippines archipelago, Taiwan, the Malaysian peninsula, Madagascar and Australia in this way. A Tropical Revolving Storm may decrease in intensity and lose its tropical characteristics in middle latitudes (35° - 45°) and become a middle latitude depression. 5.2.7 Weather conditions From the annular zone to the eye wall: Pressure decreases. Wind speed increases. Angle of Indraft decreases. Sea wave height increases. Swell wave direction is from wind field near eye. Swell wave height increases. Cloud cover is total. Precipitation increases in intensity. • • • • •
• • •
In the eye: Pressure steadies. Wind speed may be low or calm. Sea waves may be low. Swell waves are extremely high and moving in all directions. Cloud cover may be absent. Precipitation may be absent. • • • •
• •
From the eye wall to the annular zone Pressure increases. Wind speed immediately rises to maximum, then decreases. Wind direction is opposite to the original. Angle of Indraft is zero then increases. Sea wave height is maximum, then decreases. Swell wave direction is from opposite wind field near eye. Swell wave height decreases. Cloud cover is total. Precipitation is intense then decreases. • • • • • • • • •
5.3 Avoidance of Tropical Revolving Storms The following apply to tropical latitudes. 5.3.1 Warning messages Comprehensive warnings are broadcast by radio and telex of known storms and these sources should be closely monitored when navigating in areas prone to Tropical Revolving Storms in the appropriate seasons. GMDSS radio installations receive navigation warnings, including Tropical Revolving Storm warnings, automatically. Other sources are listed in the Admiralty List of Radio Signals, Volume III, and similar publications. 5.3.2 Detection Not all storms are detected by shore based meteorological services, and shipboard instruments and observation of meteorological phenomena should be used to detect the presence of a Tropical Revolving Storm. 5.3.2.1 Swell In open waters, with no intervening land, a swell generated by the high seas within a Tropical Revolving Storm may be the earliest warning of a storm. The swell approaches from the direction of the storm. 5.3.2.2 Atmospheric pressure. In the tropics the diurnal variation of atmospheric pressure is marked and a normal feature. Falling pressure in the area affected by a Tropical Revolving Storm initially damps the diurnal
5.3 Avoidance of Tropical Revolving Storms The following apply to tropical latitudes. 5.3.1 Warning messages Comprehensive warnings are broadcast by radio and telex of known storms and these sources should be closely monitored when navigating in areas prone to Tropical Revolving Storms in the appropriate seasons. GMDSS radio installations receive navigation warnings, including Tropical Revolving Storm warnings, automatically. Other sources are listed in the Admiralty List of Radio Signals, Volume III, and similar publications. 5.3.2 Detection Not all storms are detected by shore based meteorological services, and shipboard instruments and observation of meteorological phenomena should be used to detect the presence of a Tropical Revolving Storm. 5.3.2.1 Swell In open waters, with no intervening land, a swell generated by the high seas within a Tropical Revolving Storm may be the earliest warning of a storm. The swell approaches from the direction of the storm. 5.3.2.2 Atmospheric pressure. In the tropics the diurnal variation of atmospheric pressure is marked and a normal feature. Falling pressure in the area affected by a Tropical Revolving Storm initially damps the diurnal variation, and the disappearance of this feature is an early warning sign of Tropical Revolving Storm development. A barograph trace indicates this clearly. In the absence of a barograph atmospheric pressure should be noted at hourly intervals and the changes observed. The atmospheric pressure in the tropics varies little from the seasonal average. The seasonal average pressure appears in publications such as Routeing Charts and Sailing Directions. Observed atmospheric pressure should be corrected for altitude to Sea Level, and for diurnal variation. Altitude correction tables are provided to observing ships, Diurnal Variation Tables are contained in Sailing Directions. (At 25°C the rate of change of pressure with altitude is approximately 0.11 hPa per metre.) Then, comparing the seasonal average with the corrected pressure: A fall of 3 hPa below the seasonal average for the area indicates the probable development of a Tropical Revolving Storm in the vicinity. A fall of 5 hPa below the seasonal average for the area indicates the presence of a Tropical Revolving Storm, probably within 200 NM. •
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Atmospheric pressure recorded in logbooks and transmitted to meteorological services should be corrected for altitude only, not diurnal variation. Decreasing atmospheric pressure indicates the approach of a Tropical Revolving Storm. 5.3.2.3 Wind Wind direction and speed is generally fairly constant in the tropics. Variation from the normal direction for the area and season, and increasing wind speed, are indications of the approach of a Tropical Revolving Storm.
5.3.2.4 Clouds Vivid colouring of the sky at sunrise and sunset may be a precursor of a Tropical Revolving Storm. Cirrus clouds increasing in density may be visible 300 to 600 NM from the storm and are followed by lower clouds increasing in coverage as it approaches. 5.3.2.5 Visibility Exceptionally good visibility frequently exists in the vicinity of a Tropical Revolving Storm. 5.3.2.6 Radar Radar is capable of detecting the precipitation of a Tropical Revolving Storm. The range is limited and other signs will probably be manifest before the storm is within radar range. 5.3.2.7 Reporting The Master is required by SOLAS Chapter V Regulation 31 to inform the nearest authority and shipping in the vicinity if winds of Beaufort force 10 and above are encountered and no storm warning has been received. Similar warnings are required if the presence of a Tropical Revolving Storm is suspected or established. The message should include: A statement of the presence of a Tropical Revolving Storm or storm force wind Date and time UT Position of vessel Barometric pressure corrected to sea level Barometric tendency True wind direction Wind force Beaufort Sea state Swell direction, height and period Vessel’s course and speed • • • • • • • • • •
Subsequently similar messages should be transmitted at hourly intervals if possible, not greater than three hourly intervals, while the vessel is in the vicinity of the storm.
5.3.3 Avoidance
Verte
Trough
Advance
Right
Dangerous uadrant Path
Vorte
Left
Tropical Revolving Storm
Rear
Navigable
Track
5.3.3 Avoidance
Verte
Trough
Advance
Right
Rear
Dangerous uadrant Path
Vorte
Track
Left
Tropical Revolving Storm
Navigable
5.3.3.1 Features of a Tropical Revolving Storm The Track is the historical route the storm has followed. The Path is the route the storm is forecast to follow. The Trough Line is a line through the centre at right angles to the path. The Vortex is the eye of the storm. The Vertex is the westerly extremity of the path when the storm recurves. The Dangerous Quadrant is the Advance Right Quadrant of the storm in the Northern Hemisphere, and the Advance Left Quadrant in the Southern Hemisphere. This is because: • • • •
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The storm is likely to recurve in this direction. Winds tend to drive the vessel into the Path of the storm. Sea waves running toward the Path hamper movement away from the Path. The cross swell from the vicinity of the Trough Line running across the sea waves is likely to be more severe in this quadrant. Wave heights are likely to be higher in this area.
The navigable Semicircle is the Left Semicircle in the Northern Hemisphere, and the Right Semicircle in the Southern Hemisphere. The storm is unlikely to move into this area. Winds tend to drive the vessel out of the path of the storm in the advance quadrant. • •
Tropical Revolving Storm
Navigable
Right Path
Track
Dangerous uadrant
Left
Verte
Vorte
Advance
Trough
Rear
5.3.3.2 Establishing the vessel's position relative to the storm. The vessel should heave to so that the vessel's movement does not modify changes in the elements that will then be due to the storm’s movement. 5.3.3.3 The direction of the vortex Buys-Ballots law together with the angle of indraft is used to establish the direction of the centre of the storm. Face the wind. Low pressure lies on the right in the Northern Hemisphere and on the left in the Southern Hemisphere. The direction is 90° + Angle of Indraft from the wind direction. Approximate Angle of Indraft. Pressure starts to fall. 4 points. Pressure has fallen 10 hPa. 2 points. Pressure has fallen 20 hPa. 0 points. 5.3.3.4 The distance of the vortex In the absence of other information, assume that the centre is approximately 200 NM away if the pressure has fallen 5 hPa and the wind is approximately Force 6, and approximately 100 NM away if the wind is Force 8. 5.3.3.5 Relative position The following description and table may be used to establish the observer’s position relative to the storm. These are true for both northern and southern hemispheres.
Pressure: Falling. Steady. Rising.
Wind Veering
Advance. Trough line. Rear. Pressure Falling. Wind Force
Wind direction: Veering. Right semicircle. Steady. Path or track. Backing. Left semicircle. Wind force: Increasing. Steady. Decreasing.
Advance. Trough line. Rear.
Wind Directio
Pressure Rising. Wind Force
Wind
Steady conditions may indicate a stationary storm. Position relative to Tropical Revolving Storm Sector Wind Wind Direction force Path Steady Increasing Right Advance Veering Increasing Right Trough Veering Steady Line Right Rear Veering Decreasing Track Steady Decreasing Left Advance Backing Increasing Left Trough Line Backing Steady Left Rear Backing Decreasing
Pressure Falling Falling Steady Rising Rising Falling Steady Rising
5.3.3.6 The future movement of the storm In addition to the above: Storms are unlikely to move toward the equator. In latitudes less than approximately 20° storms are unlikely to move eastward. 5.3.3.7 Actions to avoid the worst effects of the storm. Northern Hemisphere Dangerous Quadrant Steer a course with the wind ahead or on the starboard bow and proceed at maximum practicable speed. Alter course as the wind veers. (From a position close to the Path it may be practicable to cross the path into the Navigable Semicircle as below.) In the Path Steer a course with the wind on the starboard quarter and proceed with maximum practicable speed into the navigable semicircle. Navigable Semicircle Steer a course with the wind on the starboard quarter and proceed with maximum practicable speed away from the path. Alter course as the wind backs. Rear
Heave to with the wind on the starboard bow and allow the storm to move clear of the intended course.
Southern Hemisphere Dangerous Quadrant Steer a course with the wind ahead or on the port bow and proceed at maximum practicable speed. Alter course as the wind backs. (From a position close to the Path it may be practicable to cross the path into the Navigable Semicircle as below.) In the Path Steer a course with the wind on the port quarter and proceed with maximum practicable speed into the navigable semicircle. Navigable Semicircle Steer a course with the wind on the port quarter and proceed with maximum practicable speed away from the path. Alter course as the wind veers. Rear Heave to with the wind on the port bow and allow the storm to move clear of the intended course. 5.3.3.8 Subsequent action. All parameters must be monitored to assess the movement of the storm, and the action taken modified accordingly. 5.3.3.9 Danger sectors When reports of the storm's position and forecast movement are available danger sectors may be plotted. The position of the storm is plotted. The forecast path is plotted. A sector is plotted centred on the position, 40° on either side of the forecast path, radius the forecast movement with an allowance for greater speed than forecast. The vessel is manoeuvred to avoid the sector. The process is repeated with each forecast received. 5.3.3.10 Other factors The actions above may have to be modified due to factors such as the proximity of land or shallow water.
5.4 Typhoon Account On 18th December 1944 the US Pacific Fleet, operating in support of the invasion of the Philippines, were caught near the centre of a Typhoon. Three destroyers capsized and sank with practically all hands. A cruiser, six light aircraft carriers and three destroyers were seriously damaged, nineteen other vessels sustained lesser damage. Fires broke out in three aircraft carriers, 146 aircraft were smashed or lost overboard and approximately 790 officers and men killed. The CO of USS "Dewey" noticed increasing sea at dusk and ordered FW and FO to be shifted from high to low tanks and ready-use ammunition moved down to magazines. By dawn, mountainous seas were running and the ship was pitching so heavily as to expose the keel as far aft as the bridge then the propellers and half the bottom were visible. The low visibility conditions increased the risk of collision and ships often would not answer their helms. The high wind speeds caused spray to peel off paintwork and to penetrate watertight instruments. Rolling was so heavy that lubricating oil suction was lost and turbines had to be stopped at the beginning of each roll. Stokers were often shoulder deep in water, hanging on to anything available and swinging out nearly parallel to the deck. When the funnel guys parted, the funnel went over the side and improved the stability. After five hours the destroyer came out of the murk and spume into clear sky, the wind dropped to 50 knots and the ship was got under control again. The C. in C. (Admiral Nimitz) wrote to the fleet: Possibly too much reliance was placed on the analysis broadcast from the Fleet Weather Centre ... weather data was lacking for an area of about 300 miles in diameter (where the storm was centred) and the immediate signs of it were not heeded early enough. Losses were accentuated by efforts of vessels to maintain Fleet courses and speeds and formations during the storm. The Admiral drew attention to the fact that in the days of sail a ships survival ... depended almost solely on the competence of the master and on his constant alertness to every hint of change in the weather ... a seaman was culpable who regards personal weather estimates as obsolete and assume that if no radio storm warning has been received then all is well and no local signs need cause him concern'. He stressed that each CO should refresh himself on 'Knight' and 'Bowditch', not only as to the 'Law of Storms' but also as to Ship Handling in Heavy Weather. The following conditions were experienced in the storm. Very poor visibility. Ships in addition to heavy rolling were being heeled continually by the violent wind leaving little margin of stability for any further rolling The ships that were lost took a long roll to leeward varying from 50° to 80°, hung there and then capsized and sinking almost immediately. Water was shipped through intakes, ventilation and all upper deck openings, short-circuiting electrical switchboards and machinery and causing fires. Free surface in E.R. and other compartments. Complete loss of steering control, power, lighting and navigational -instrumentation and all communications. Main Engine stoppage. Wind speeds and seas which carried away masts, funnels, boats, davits and deck structures. The cruiser "Pittsburgh" lost 100 feet off her bow. The flight decks of aircraft carriers were peeled back like a banana skin. It was impossible for men to secure gear that had gone adrift or to jettison any topweight or even to stay up where they would have had a chance of getting clear of the sinking ship. These experiences brought a suggestion from the C. in C. British Pacific Fleet that when destroyers with only 50% FO were in the vicinity of a Tropical Revolving Storm, the tanks should be flooded with sea water as had, up till then, only been permitted in exceptional circumstances, eg in Arctic waters.
5.5 Tropical Revolving Storm Forecasts The following is the text of a warning that illustrates the format and type of information given. Different authorities’ warnings differ in presentation. WTPN31 PGTW 110300 MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/TROPICAL CYCLONE WARNING// 1. SUPER TYPHOON 03W (SUDAL) WARNING NR 029 01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE --WARNING POSITION: 110000Z2 --- NEAR 13.2N6 132.2E8 MOVEMENT PAST SIX HOURS - 320 DEGREES AT 09 KTS POSITION ACCURATE TO WITHIN 025 NM POSITION BASED ON EYE FIXED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 130 KT, GUSTS 160 KT BECOMING EXTRATROPICAL RADIUS OF 100 KT WINDS - 020 NM RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 165 NM NORTHEAST QUADRANT 155 NM SOUTHEAST QUADRANT 155 NM SOUTHWEST QUADRANT 165 NM NORTHWEST QUADRANT REPEAT POSIT: 13.2N6 132.2E8 --FORECASTS: 12 HRS, VALID AT: 111200Z5 --- 14.3N8 131.4E9 MAX SUSTAINED WINDS - 135 KT, GUSTS 165 KT RADIUS OF 100 KT WINDS - 025 NM RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 065 NM SOUTHEAST QUADRANT 065 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 165 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 160 NM SOUTHWEST QUADRANT 165 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 340 DEG/ 05 KTS --24 HRS, VALID AT: 120000Z3 --- 15.3N9 131.0E5 MAX SUSTAINED WINDS - 135 KT, GUSTS 165 KT RADIUS OF 100 KT WINDS - 030 NM RADIUS OF 050 KT WINDS - 075 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 075 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 170 NM NORTHEAST QUADRANT 165 NM SOUTHEAST QUADRANT 165 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 010 DEG/ 06 KTS
36 HRS, VALID AT: 121200Z6 --- 16.5N2 131.2E7 MAX SUSTAINED WINDS - 125 KT, GUSTS 150 KT RADIUS OF 100 KT WINDS - 025 NM RADIUS OF 050 KT WINDS - 060 NM RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 150 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 020 DEG/ 08 KTS --EXTENDED OUTLOOK: 48 HRS, VALID AT: 130000Z4 --- 18.0N9 131.7E2 MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT RADIUS OF 100 KT WINDS - 020 NM RADIUS OF 050 KT WINDS - 055 NM RADIUS OF 034 KT WINDS - 145 NM NORTHEAST QUADRANT 145 NM SOUTHEAST QUADRANT 135 NM SOUTHWEST QUADRANT 135 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 030 DEG/ 10 KTS --72 HRS, VALID AT: 140000Z5 --- 21.5N8 134.0E8 MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT BECOMING EXTRATROPICAL RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT 115 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 115 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 045 DEG/ 17 KTS --LONG RANGE OUTLOOK: NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM ON DAY 4 AND 350 NM ON DAY 5... AND FOR INTENSITY NEAR 20 KT EACH DAY. --96 HRS, VALID AT: 150000Z6 --- 26.1N9 139.6E9 MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT BECOMING EXTRATROPICAL VECTOR TO 120 HR POSIT: 060 DEG/ 27 KTS --120 HRS, VALID AT: 160000Z7 --- 30.9N2 150.7E3 MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT BECOMING EXTRATROPICAL --REMARKS: 110300Z5 POSITION NEAR 13.5N9 132.0E6. SUPER TYPHOON (STY) 03W (SUDAL), LOCATED APPROXIMATELY 410 NM WEST-NORTHWEST OF YAP, HAS TRACKED NORTHWESTWARD AT 09 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION IS BASED ON 102330Z9 ENHANCED MULTISPECTRAL SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF
115 AND 140 KNOTS. ENHANCED INFRARED SATELLITE IMAGERY INDICATES THE EYE TEMPERATURE HAS WARMED APPROXIMATELY 30 DEGREES CELSIUS OVER THE PAST SIX HOURS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 110000Z2 IS 38 FEET. REFER TO WWPW30 RJTX FOR ADDITIONAL SEA HEIGHT INFORMATION. NEXT WARNINGS AT 110900Z1, 111500Z8, 112100Z5 AND 120300Z6.// NNNN
