Property of Lear Siegler
FRONTAL WEATHER
Property of Lear Siegler
Terminal Learning Objective
Page D-1 in Student Handout:
ACTION:
CONDITION:
STANDARD:
ELO
Identify the characteristics common to all fronts IAW FM 1-230.
A FRONT IS A BOUNDARY BETWEEN AIR MASSES
OF DIFFERENT DENSITIES.
COLDWARM
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Frontal formation: When two high pressure cells exist so that the circulation of air is converging between
them, a front is formed. The converging air currents veer upward creating a zone (trough) of low pressure.
COLD WARM
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H
H
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cP
mT
L
Frontal weather is caused by the lifting of warm moist air by colder more dense air.
ALL FRONTS HAVE A TEMPERATURE INVERSION
FRONTAL DISCONTINUITIES
• TEMPERATURE
• DEWPOINT
• PRESSURE “ FALL THEN RISE”
• WIND SHIFT : APPROX 90°
DRIFT CORRECTION TO THE RIGHT
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Primary factors affecting frontalweather are slope, speed,
moisture content, and stability.
questions ?
ELO
Identify the general characteristics of a cold front IAW FM 1-230.
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Cold Front
The leading edge of a cold air mass, normally moving toward the southeast.
Cold Front
• Slope• Clouds• Width of weather band• Winds• Direction of movement• Speed• Symbol
Cold Front
Slope – avg. 1:80
80 miles
1 m
ile
CUMULONIMBUS
10,000’
15,000’
20,000’
25,000’
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Cold Front
cumuliform predominant
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type of weather
Cold Front
Post-frontal, can be violent
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Width of weather band
50 miles
Cold Front
sout
hwes
t
northwest
Cold Front Winds
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southeast
Direction of Movement
Average 25 knots
Speed
Speed
WARNING!If speed of front exceeds 25 kts a squall
line may form as much as 300 milesahead. Squall lines may include
tornadoes, hail, and destructive winds!
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Property of Lear Siegler
SQUALL LINE
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Symbol
color - blue
triangle shapes,pointing in direction
of movement
NOTE: You must recognize
in color and black and white.
questions ?
ELO
Identify the general characteristics of a warm front IAW FM 1-230.
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Warm Front
The trailing edge of a cold air mass, normally moving generally toward the northeast,
being overridden by warmer air.
Warm Front
• Slope• Clouds• Width of weather band• Winds• Direction of movement• Speed• Symbol
Warm Front
Slope – avg. 1:200
200 miles
1 m
ile
Property of Lear Siegler
stratiform predominant
Warm Front
Ci
Cs
As
Ns
St
10,000’
15,000’
20,000’
25,000’
0 100 200 300 400 500 MILES
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Width of weather band
400 to 600 miles
WARM FRONT
WARM FRONT
southeast
southwest
Winds
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WARM FRONT
northeast
Direction of Movement
WARM FRONT
Speed
Average 15 kn
ots
WARM FRONT
Symbol
color - red
NOTE: You must recognize
in color and black and white.
half moon shapes,pointing in direction
of movement
questions ?
ELO
Identify the general characteristics of a stationary front IAW FM 1-230.
Stationary Front
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A front which is not moving, speed of zero to less than 5 knots.
Stationary Front
• Slope• Clouds• Width of weather band• Winds• Direction of movement• Speed• Symbol
similar towarm front
Stationary Front
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Winds – light andvariable, tend toparallel isobars.
Movement - unpredictableSpeed – zero to < 5 kts
Stationary Front
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color – alternatingred and blue
NOTE: You must recognize
in color and black and white.
combination of symbolsfor cold and warm fronts,
alternating sides ofline of front
questions ?
ELO
Identify the general characteristics of an open wave IAW FM 1-230.
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Open Wave
A wave-like appearance with one portion a cold front and the other a warm front with an open area in
between.
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Open Wave
Vertical cross section.
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Open Wave
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Open Wave
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Open Wave
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Open Wave
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Open Wave
Weather
Cold front WX
Warm front WX
Warm air
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Open Wave
Movement
Travels in easterly direction along the line of
the original front
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Open Wave
Weather chart portrayal
Cold front
Warm front
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questions ?
ELO
Identify the general characteristics of an occluded front IAW FM 1-230.
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Open Wave
Occluded Front:The result of a faster moving cold front overtaking a slower moving warm front.
The effect is one front on top of the other squeezing warm air between.
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Open Wave
15 kts.
25 kts.
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Open Wave
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Cold Occlusion
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Cold Occlusion
Two types of occlusions:
Cold front occlusion – The cold front runs underneath the warm front.
(coldest air is behind the cold front)
Warm front occlusion – The cold front overruns the warm front.
(coldest air is ahead of the warm front)
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Open Wave
Cold front occlusion – The cold front runs underneath the warm front.
(coldest air is behind the cold front)
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Cold Occlusion
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Cold Occlusion
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Open Wave
Warm front occlusion – The cold front overruns the warm front.
(coldest air is ahead of the warm front)
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Warm Occlusion
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Warm Occlusion
Occlusions: cloud types
Both warm and cold front typesstratiform and cumuliform
Occlusions: weather
Weather associated with each of these frontscombines widespread low ceilings and poorvisibilities of the warm front with the severe
weather of the cold front.
Occlusions: winds
Ahead of the occlusion vary south to eastgenerally from the southeast,
behind the front generally from the northwest.
Occlusions: movement
Similar to an open wave, to the east
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Cold Occlusion
Travels in easterly direction along the line of
the original front
Portrayal:cold occlusion
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Warm Occlusion
Portrayal:warm occlusion
questions ?
ELO
Identify the proper flight proceduresto use when dealing with
frontal weather IAW FM 1-230.
RECOGNITION OF TYPE:Each type front presents certain problems
to the aviator. The aviator must learn to recognize type of front in
order to apply proper procedures.
FLIGHT CONSIDERATIONS:Cold fronts and squall lines
DON’T GO!
FLIGHT CONSIDERATIONS:Warm fronts
Sufficient fuel for a long flight and possiblediversion to an alternate airfield
FLIGHT CONSIDERATIONS:Stationary fronts
Same as warm front, plusalert for open wave and occlusion
FLIGHT CONSIDERATIONS:Open wave
Avoid the crest of the wave andcold front, cold front procedures
for cold side, warm front procedures for warm side
FLIGHT CONSIDERATIONS:Occluded fronts
WARNING!Occluded fronts offer worst possible weather! Avoid the apex
of the occlusion by at least 50 to 100 miles. Circumnavigate to right (tailwinds). Do not fly through an
occluded front. Wait, circumnavigate, or fly through stationary/warm front separately.
questions ?
ELO
Identify indications of frontal passage IAW FM 1-230.
On the ground
• wind shift•Temperature•Dew point•pressure
In flight
• more difficult to recognize• best indicator is OAT gauge• anticipate drift correction to right (with possible exception of occlusion)
questions ?
The endThe end