Tool 7: Case Study – Thunderstorm Case in
Note: This case study is provided in French by
L’ Agence
pour la Sécurité
de la Navigation Aérienne en
Afrique
et à Madagascar (ASECNA) as an example of
using a case study to evaluate certain performance criteria. The following condensed description has
been translated into English. The
case study is extracted from a direct observation assessment process during the
wet season. It is an example of
best practice with the hope that it may be emulated in other locations for
important but infrequent events. In
tropical regions, thunderstorms tend to be more seasonal and are very rare in
the dry season. Demonstrating this competence would not
be practical in dry season using direct observation. Successful completion of the case study
would satisfy several performance criteria. As with many competencies, there is no
guarantee that success on the test or case study would transfer to a real-time
situation. Should deficiencies be
noted later, corrective action would be required and should be described within
the quality management system of the specific organization. Human nature is such that, even for perfectly
demonstrated competence, in a real situation, there is no absolute certainty
that the individual will demonstrate the same competence on a different
day. There is a strong probability
of continued competence but no guarantee.
For this reason, as part of a quality management system, ongoing
competency demonstration is required.
Satisfies
the following performance criteria:
1.3
assessing the need for amendments
2.1h
forecasting thunderstorms
2.3a
monitoring adjacent regions
2.3b
liaise with adjacent regions
3.1a
forecasting severe thunderstorms
5.2
delivering briefings
The
full case study in French, with accompanying information, can be downloaded
from (insert link here).
The
forecaster is asked to prepare a briefing for a flight crew departing at 13h50
UTC with the flight route Lomé –
·
forecast winds
and temperatures for FL180, FL340 and FL450
·
high altitude
significant weather chart valid August 4 at 18 UTC
·
ascent forecast
from Lomé (
·
approach forecast
for
In addition, he or she is asked
to consider the forecasts provided and what, if any action should be
taken. This could include amending
forecasts, issuing warnings, contacting clients or other regions.
As part of the case study,
the forecaster is given access to
·
standard analysis
and forecast charts for August 4
·
forecast upper
level winds for 18 UTC August 4 for FL180, FL340, FL390, FL450
·
WAFC sig weather
chart FL250 and higher valid 18 UTC August 4
·
satellite imagery
·
surface and
aircraft reports from the region
·
any TAFs or SIGMETs in effect in the
region
·
NWP
Assessment criteria – case study outcomes
·
The forecaster
should consider the enroute portion of the flight
from Lomé to
·
The forecaster
should notice the convective development over northwestern
·
The motion of
this convective complex should be noted (toward the SW at 15-20 m/sec).
·
In addition, the
forecaster should remark that the thunderstorms may reach Niamgtougou
(
·
The forecaster
should examine forecasts from adjacent regions and initiate communication as
appropriate.
·
The examination
of the satellite image at 11 UTC suggests that the convective area might be
weakening. However, examination of
analysis and model data shows confluence at 700 hpa
as well as a convergence zone at 850 hpa over the
northern and north-eastern part of
·
Thus, the
forecaster should expect the area of thunderstorms to continue its current
motion while intensifying.
·
The forecaster
should consider the requirement for a SIGMET as well as any associated
warnings.
A similar case study model
could also be developed for other infrequent or seasonal phenomena such as
·
2.1e -
Forecasting precipitation
·
2.1f -
Forecasting reduced visibility, onset and duration
·
2.1g -
Forecasting obstructions to vision
·
2.1h -
Forecasting thunderstorms
·
2.1i -
Forecasting turbulence
·
2.1j -
Forecasting icing
·
2.1k -
Forecasting wake vortex formation, movement and dissipation
·
3.1a - Warnings
for severe thunderstorms
·
3.1b - Warnings
of severe turbulence
·
3.1c - Warnings
for severe winds, wind shear, variability and gusts
·
3.1d - Warnings
for severe icing
·
3.1e -
Forecasting hazardous phenomena affecting aerodromes