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 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

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 - Least Dangerous (Navigable) Semi-circle - side that is left of storm center and direction of path

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

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.

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.

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

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

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.

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

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

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

Services Available 1.Tropical Cyclone Alert 2. High Wind and Sea Warning 3. Local Severe-Storm Warning 4. WEAX 5. OTSR - Optimum Track Ships Routing

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.

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

Weather Prediction Heuristics  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

Weather Prediction Heuristics  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

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

Questions?