Lesson 15B: Storm Avoidance

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Lesson 15B Storm Avoidance
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Lesson 15B Storm Avoidance

• AGENDA
• Storm Avoidance
• Weather Reporting
• Weather Prediction
• Applicable reading Hobbs WB, App A

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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 storms travel
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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
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Northern Hemisphere
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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.
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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.
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Storm Avoidance
6. Safe Passage - in the Northern Hemisphere -
On Storm Track (behind) Avoid the center by
best practical course (southerly).
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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
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Ship Observation Reporting
Synoptic - Formatted weather message - Every
6 hours PRIORITY if surface wind speeds lt
33 kts, seas lt 12 feet. - Every 3 hours
IMMEDIATE if surface winds gt 33 kts
sustained, seas gt 12 feet. - Via plain voice
first indications of a tropical cyclone,
unusual or hazardous weather.
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Ship Observation Reporting
Weather Observations - prepared by OOD - Type
of observation - Cloud Cover - Prevailing
visibility - Weather obstructions to
visibility - Sea level pressure in millibars
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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
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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
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Services Available

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

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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.

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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

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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

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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 sailors delight
• Red sky at morning ... sailors take warning

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Review/Summary

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

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Questions?