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FALL & WINTERFALL & WINTER CLIMO CLIMO AND AND HAZARDSHAZARDS BRIEFING! BRIEFING!

Sacramento, CA

DET 32 OSA FY08

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November ClimatologyNovember Climatology

(Monthly Averages)

Temp :53F High Temp :64F Low Temp :43 Precipitation :2.2 inches Clear days :10 Cloudy days :13 Partly Cloudy days :7 Rainy days :7

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December ClimatologyDecember Climatology

(Monthly Averages)

Temp :46F High Temp :53F Low Temp :38F Precipitation :2.8 inches Clear days :8 Cloudy days :17 Partly Cloudy days :6 Rainy days :9

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January ClimatologyJanuary Climatology

(Monthly Averages)

Temp :46F High Temp :53F Low Temp :38F Precipitation :3.7 inches Clear days :7 Cloudy days :18 Partly Cloudy days :6 Rainy days :10

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February ClimatologyFebruary Climatology

(Monthly Averages)

Temp :51F High Temp :60F Low Temp :41F Precipitation :2.8 inches Clear days :8 Cloudy days :13 Partly Cloudy days :6 Rainy days :9

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March ClimatologyMarch Climatology

(Monthly Averages)

Temp :54F High Temp :64F Low Temp :43F Precipitation :2.6 inches Clear days :10 Cloudy days :13 Partly Cloudy days :8 Rainy days :9

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April ClimatologyApril Climatology

(Monthly Averages)

Temp :59F High Temp :71F Low Temp :46F Precipitation :1.2 inches Clear days :12 Cloudy days :8 Partly Cloudy days :10 Rainy days :5

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General Winter General Winter HazardsHazards

IcingTurbulenceWhite Out ConditionsPersonnel Activities

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ICINGICINGHAZARDSHAZARDS

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ICING HAZARDSICING HAZARDS

Mostly occurs in cloud, but can occur below if ....

1) Precip is liquid and aircraft skin is below freezing. 2) Precip is falling from warmer layer on to an aircraft that is in a

colder layer below.

Types of Icing 1) Frost 2) Rime 3) Clear 4) Mixed (This is not a type by itself. It is actually a mixture of

Rime and Clear ice.)

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ICING HAZARDS CONT.ICING HAZARDS CONT.

Can Seriously degrade aircraft performance by...

1) Increasing aircraft weight. 2) Increasing the drag of the aircraft. 3) Decreasing lift. 4) and, Freezing up the aircraft control surfaces.

BEWARE. ICING CAN KILL!!BEWARE. ICING CAN KILL!!

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WAYS TO MINIMIZE ICINGWAYS TO MINIMIZE ICING

Remove ice and snow from aircraft before takeoff. Avoid flying in clouds when outside air

temperature is 0 c to -20 c. Use all necessary anti-ice and de-ice equipment. If icing is encountered, climb or descend to an

altitude where the temperature is warmer than 0 c or colder than -20 c.

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TURBULENCETURBULENCEHAZARDSHAZARDS

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TYPES OF TURBULENCETYPES OF TURBULENCE

Most common types during winter are...– Mechanical...

Results when obstructions such as buildings, trees, and rough terrain disrupt smooth wind flow. The degree of this turbulence depends on wind speed and roughness of the obstructions (ie. The higher the wind speed and / or the rougher the surface, the greater the turbulence will be.

Mountain Wave... Are areas of steady updrafts and downdrafts associated with the

mountain wave may extend to as far as 300 miles downstream from a mountain range. Moderate to severe turbulence is common with this type of turbulence.

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TURBULENCE INTENSITIESTURBULENCE INTENSITIES( Note: This is only one tool that can be used for Turb.)( Note: This is only one tool that can be used for Turb.)

Intensity Vertical Speed Change

Light

Moderate

Severe

Extreme

3-5 kts per 1000 ft

6-9 kts per 1000 ft

10-15 kts per 1000 ft

>15kts per 1000 ft

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MECHANICAL MECHANICAL TURBULENCE LOCATIONSTURBULENCE LOCATIONS

Mechanical Turbulence Locations... In or near cumulus or cumulonimbus clouds. Areas with drastic change in topography. Areas where winds blow over structures or uneven ground. In valleys or canyons. In the vicinity of frontal systems.

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MOUNTAIN WAVE LOCATION MOUNTAIN WAVE LOCATION AND INDICATORSAND INDICATORS

Mountain Wave Turbulence Location... When winds are greater than 25 kts blowing perpendicular

across the tops of mountains.

Mountain Wave Indicators Blowing dust downwind of high terrain. Fluctuations of the airspeed indicator and the vertical velocity

indicator. If any of the following clouds are present.

– Lenticular clouds

– Rotor (Roll) clouds

– Cap cloud

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LOW LEVEL WIND SHEARLOW LEVEL WIND SHEAR

LLWS is the primary or probable cause of several aircraft incidents and accidents worldwide. It is most dangerous within 2,000 feet of the ground.

Where to expect Low Level Wind Shear... At the top of Radiation inversions. Near frontal boundaries Where surface winds are at least 30 kts or more. Near mountains, and along straits and channels.

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LLWS CONT.LLWS CONT.

LLWS Indicators– Abnormal power setting and rate of decent required to maintain

glidepath.

– Fluctuations in indicated air speed and vertical velocity indicators.

– Large difference between IAS and ground speed.

– Significant difference between approach wind and reported surface winds.

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WHITE OUTWHITE OUTCONDITIONSCONDITIONS

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WHITE OUT CONDITIONSWHITE OUT CONDITIONS

Occur when landing or hovering near the ground.

Can occur with very little snow on the ground.

Most often occurs with freshly fallen, fine, dry snow flakes.

Can reduce visibility down to 0 feet in seconds.

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HAZARDS TO HAZARDS TO PERSONNELPERSONNEL

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Cold Weather InjuriesCold Weather Injuries

Frostbite– Dress warmly in loose layers– Wear gloves and other cold weather gear when

outside for long periods of time– Don’t touch metal or snow with bare hands

Hypothermia– Stay dry and warm

Trenchfoot– Wear dry and insulated boots

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WindchillWindchill Cold Temperatures combined with strong winds

can make it feel very cold Wind Chill Temperatures

– Above -20F = Little Danger– From -20F to -70F = Flesh may freeze in 1 min– Below -70F = Flesh may freeze in 30 sec

Low wind chills can be caused by rotor wash and moving vehicles

Protect Yourself!

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Driving ConditionsDriving Conditions

Know the Road Conditions Drive slow and stay in control Snow and Ice can sneak up on you due to

low visibility Use your brakes wisely Use your chains to maintain traction

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QUESTIONS?QUESTIONS?

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Thank You For Your Attention!Thank You For Your Attention!If you have any other questions If you have any other questions

please contact your local weather please contact your local weather facility. facility.