IRFP-01
Metro Review
(c) Often develop into uninterrupted lines that are difficult
to circumnavigate
(2) Warm front
(a) Generated when a warm and moist air mass is lifted
(slides over) a cold air mass
(b) Less common and less violent than cold front due to
more stability and less lifting force within the air mass
(c) Often embedded or obscured in stratiform clouds,
making them difficult to see and avoid
c.
Squall line: band or line of severe thunderstorms
(1) Usually associated with fast-moving cold fronts
(a) Usually form 50 to 300 miles ahead of the front—but
can also form in most unstable airmasses
(b) Generally caused by upper airflow disturbance
(c) Build rapidly and are most severe in late afternoon and
early evening
(2) Uninterrupted lines of cells often too long and wide to
avoid--can be too high to fly over (more than 55,000 ft)
(3) Characterized by severe steady-state thunderstorms or
“supercells” that can contain tornadoes, hail, and other
severe hazards to aviation
2. Thunderstorm hazards 21.1.1.4.5
a. Turbulence
(1) Hazardous turbulence present in all thunderstorms
(a) Up and down drafts can obtain speeds of 200 ft per
second
(b) Up drafts are usually stronger than down drafts
(2) Aircraft control difficult to impossible
(3) Can be severe enough to cause structural damage or
failure
NOTE: The storms that create the most violent turbulence
are often producers of hail.
(8-97) Original
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