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Lesson 15B: Storm Avoidance

Lesson 15B: Storm Avoidance. Lesson 15B: Storm Avoidance. AGENDA: Storm Avoidance Weather Reporting Weather Prediction Applicable reading: Hobbs WB, App A. Storm Avoidance. 1. Hurricane Season - June through November

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Lesson 15B: Storm Avoidance

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  1. Lesson 15B: Storm Avoidance

  2. Lesson 15B: Storm Avoidance • AGENDA: • Storm Avoidance • Weather Reporting • Weather Prediction • Applicable reading: Hobbs WB, App A

  3. Storm Avoidance 1. Hurricane Season - June through November 2. Procedure - Safest with respect to tropical cyclones is avoidance. 3. Key Elements to Determine: - Position relative to storm center & axis - Path & velocity of storm’s travel

  4. Storm Avoidance 4. Cyclonic Storms - Deflected by the corriolis effect travel in a clockwise direction (Northern Hemisphere). 5. Storm Division - Storm is divided into 2 parts: - Most Dangerous Semi-circle - side that is right of storm center and direction of path - LeastDangerous (Navigable) Semi-circle - side that is left of storm center and direction of path

  5. Northern Hemisphere Most Dangerous Quadrant More Dangerous Semi-circle Least Dangerous Semi-circle

  6. Storm Avoidance 6. Safe Passage - in the Northern Hemisphere - Avoid crossing the “T”: avoid passing in front of a storm going from Most to Least Dangerous semi-circle - Most Dangerous Semi-Circle: Bring the wind on STBD bow, hold course & make best speed.

  7. Storm Avoidance 6. Safe Passage - in the Northern Hemisphere - Least Dangerous Semi-Circle: Bring the wind on STBD qtr, hold course & make best speed. - On Storm Track (ahead): Bring the wind to 160 deg R until a backing is noted in the wind (indicating you are in the Least Dangerous Semi-circle), then bring the wind on STBD quarter, hold course & make best speed.

  8. Storm Avoidance 6. Safe Passage - in the Northern Hemisphere - On Storm Track (behind): Avoid the center by best practical course (southerly).

  9. Ship Observation & Reporting Weather Observations - Ships are required to take regular weather observations: - Observations taken hourly IAW NAVOCEANINST. - Ships in company, OTC may designate one ship to report observations - In port with no manned weather facility within 50NM

  10. Ship Observation & Reporting Synoptic -Formatted weather message: - Every 6 hours PRIORITY if: surface wind speeds < 33 kts, seas < 12 feet. - Every 3 hours IMMEDIATE if: surface winds > 33 kts sustained, seas > 12 feet. - Via plain voice: first indications of a tropical cyclone, unusual or hazardous weather.

  11. Ship Observation & Reporting Weather Observations -prepared by OOD: - Type of observation - Cloud Cover - Prevailing visibility - Weather & obstructions to visibility - Sea level pressure in millibars

  12. Ship Observation & Reporting Weather Observations -prepared by OOD: (cont.) - Dry bulb temp in degrees fahrenheit - Dew point temp in degrees fahrenheit - True wind direction & speed - Altimeter setting (if aircraft embarked) - Remarks

  13. Ship Observation & Reporting Weather Observations -prepared by OOD: (cont.) - Station pressure in inches of mercury - Sea water temp (at sea water injection) - Sea height, direction and period - Ice (if applicable) - Clouds by type, quantity, & height

  14. Services Available • Tropical Cyclone Alert 2. High Wind and Sea Warning 3. Local Severe-Storm Warning 4. WEAX 5. OTSR - Optimum Track Ships Routing

  15. Weather Prediction • Broadcast WEAX Messages • High Seas Warnings • Offshore Marine Forecasts • Coastal Marine Forecasts • OPAREA Forecasts • OTSR (Optimum Track Ship Routing) • Tailored track recommendations • National Data Buoy Collection Center • Provides real-time conditions throughout coastal U.S.

  16. Weather Prediction • 42039 PENSACOLA • 56 NM South of Panama City, FL • Measures: • Wind direction, speed • Wave height, period • Atmos. Pressure • Air/Water Temperature • Dew Point

  17. Weather PredictionHeuristics • Look for changes in wind direction • Veering: clockwise movement • Backing: counter-clockwise movement • Watch 3 hour trend of barometer • Note cloud type and direction • Monitor dew point spread

  18. Weather PredictionHeuristics • Buys Ballot Law • To locate High or Low use: • Stand with your back to the wind • Turn 15º to the right • The LOW is on your left, the HIGH on your right • Red sky at night … sailor’s delight • Red sky at morning ... sailors take warning

  19. Review/Summary • Describe the difference between the dangerous semi-circle and the navigable semi-circle. • What is OTSR used for?

  20. Questions?

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