Property of Lear Siegler. FRONTAL WEATHER Property of Lear Siegler

Property of Lear Siegler

FRONTAL WEATHER


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


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


H

H


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


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.


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’


Cold Front

cumuliform predominant


type of weather

Cold Front

Post-frontal, can be violent


Width of weather band

50 miles

Cold Front

sout

hwes

t

northwest

Cold Front Winds


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!



SQUALL LINE


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.


Warm Front

The trailing edge of a cold air mass, normally moving generally toward the northeast,

being overridden by warmer air.

Warm Front


Warm Front

Slope – avg. 1:200

200 miles

1 m

ile


stratiform predominant

Warm Front

Ci

Cs

As

Ns

St

10,000’

15,000’

20,000’

25,000’

0 100 200 300 400 500 MILES


Width of weather band

400 to 600 miles

WARM FRONT

WARM FRONT

southeast

southwest

Winds


WARM FRONT

northeast

Direction of Movement

WARM FRONT

Speed

Average 15 kn

ots

WARM FRONT

Symbol

color - red



half moon shapes,pointing in direction

of movement

questions ?

ELO

Identify the general characteristics of a stationary front IAW FM 1-230.

Stationary Front


A front which is not moving, speed of zero to less than 5 knots.

Stationary Front


similar towarm front

Stationary Front


Winds – light andvariable, tend toparallel isobars.

Movement - unpredictableSpeed – zero to < 5 kts

Stationary Front


color – alternatingred and blue



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.


Open Wave

A wave-like appearance with one portion a cold front and the other a warm front with an open area in

between.


Open Wave

Vertical cross section.


Open Wave



Open Wave


Open Wave


Open Wave


Open Wave

Weather

Cold front WX

Warm front WX

Warm air


Open Wave

Movement

Travels in easterly direction along the line of

the original front


Open Wave

Weather chart portrayal

Cold front

Warm front


questions ?

ELO

Identify the general characteristics of an occluded front IAW FM 1-230.


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.


Open Wave

15 kts.

25 kts.


Open Wave


Cold Occlusion


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)


Open Wave

Cold front occlusion – The cold front runs underneath the warm front.

(coldest air is behind the cold front)


Cold Occlusion


Cold Occlusion


Open Wave

Warm front occlusion – The cold front overruns the warm front.

(coldest air is ahead of the warm front)


Warm Occlusion


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


Cold Occlusion

Travels in easterly direction along the line of

the original front

Portrayal:cold occlusion


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

Documents

Property of Lear Siegler. FRONTAL WEATHER Property of Lear Siegler