Transcript SECTION 12 CONSTANT PRESSURE ANALYSIS CHART

SECTION 5, 6
HOMEWORK
• READ AC 00-45
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Constant Pressure Charts (Section 5.2)
Freezing Level Graphics (Section 5.3)
Lifted Index Analysis Chart (Section 5.4)
Convective Outlook Chart (Section 6.4)
Products for Tropical Cyclones (Section 6.5)
Volcanic Ash Advisory Products (Section 6.6)
Review Section 5.5-5.7
Weather Depiction Chart
Radar Summary Chart
Convective Sigmets, Sigmets and Airmets
Australia Accident
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Police say both planes were on the ground at Gunbalanya, about 330 kilometres east of Darwin,
when one of the plane's engines started up after its pilot accidentally knocked the propeller. Senior
Constable Nathan Conelius says the pilot had been in the process of preparing the aircraft to be
taxied to another area when he exited the aircraft and accidentally knocked the propeller, causing the
engine to start.
"The plane's moved forward at full speed for about 20 metres before it's collided with the rear of
another Cessna, which caused extensive damage to the tail and wing of that plane.
"The collision sent debris flying over an area about the size of a football field."
He says the damaged plane is a write-off.
The pilot was breath-tested but returned a negative alcohol reading.
The Australian Transport and Safety Bureau was notified but the bureau says it is unlikely to
investigate the matter further.
"We're satisfied that it was just a simple accident and we won't be taking the matter any further,"
Senior Constable Conelius said.
HPC Aviation Charts
• HPC Surface Analysis Charts
– http://www.hpc.ncep.noaa.gov/html/sfctxt.html
#avnsfc
– Search cntrl f “aviation”
• Zoom in aviation HPC aviation charts
– http://www.hpc.ncep.noaa.gov/sfc/awcsfcwbg.g
if
Meteorological Calculators
• http://www.hpc.ncep.noaa.gov/html/calcbod
y_txt.html
HPC Short Range Forecasts
• Short Range Forecasts (Fronts and
Precipitation)
– http://www.hpc.ncep.noaa.gov/html/fcsttxt.html
#shortrange
HPC Forecasts
• HPC Quantitative Precipitation and
Snow Forecasts
– http://www.hpc.ncep.noaa.gov/qpf/qpftxt.html
HPC Medium Range Forecasts
• http://www.hpc.ncep.noaa.gov/html/fcsttxt.
html#mediumrange
• 3-7 day forecast products
• Heat Index Products
• http://www.hpc.ncep.noaa.gov/html/fcsttxt.
html#heatindex
• Other Products
• http://www.hpc.ncep.noaa.gov/html/fcsttxt.
html#otherprod
ASOS Userguide
• http://www.nws.noaa.gov/asos/pdfs/aumtoc.pdf
SECTION 5.2 CONSTANT
PRESSURE ANALYSIS CHART
• Constant Pressure Chart
– Combining these charts help to determine the
three-dimensional aspect of depicted pressure
systems.
SECTION 8 CONSTANT
PRESSURE ANALYSIS CHART
• Constant Pressure Chart
– Alternate term for Isobaric Chart; a weather map
representing conditions on a surface of equal atmospheric
pressure. For example, a 500 mb chart will display
conditions at the level of the atmosphere at which the
atmospheric pressure is 500 mb. The height above sea level
at which the pressure is that particular value may vary from
one location to another at any given time, and also varies
with time at any one location, so it does not represent a
surface of constant altitude/height (i.e., the 500 mb level
may be at a different height above sea level over Dallas than
over New York at a given time, and may also be at a
different height over Dallas from one day to the next).
CONSTANT PRESSURE
ANALYSIS CHART
• Computer generated is observed primarily
by balloon ascending radiosonde packages.
• Each package consists of wx instruments
and a radio transmitter.
• Covers a surface of equal pressure
• twice daily
• valid at 12Z and 00Z balloon released at
this time as well.
Where to find these charts
• http://weather.noaa.gov/fax/barotrop.shtml
• http://www.erh.noaa.gov/gyx/weather_balloons.htm
Radiosonde Network
CONSTANT PRESSURE
ANALYSIS CHART
• Data from each observation station are
plotted around a station circle on each
constant pressure chart. The circle identifies
the station position. The data plotted on each
chart are:
• Temperature, temperature/dew point spread,
wind, height of the surface above sea level,
and height change of the surface over the
previous 12- hour period
CONSTANT PRESSURE
ANALYSIS CHART
• The temperature and spread are in degrees
Celsius, wind direction is relative to true
north, wind speed is in knots, and height and
height change are in meters. The station
circle is shaded black when the spread is 5
degrees or less (moist atmosphere), and open
when spread is more than 5 degrees (dry
atmosphere)
STATION DATA
• Wind: Triangle=50knots, large line=10knots,
small line 10knots.
• Wind direction is in degrees true
• Wind speed in knots
• If wind data is missing the letter “M” is
plotted in the pressure section.
STATION DATA
• Height is found in the top right hand corner
and gives the height of the constant pressure
surface in meters above mean sea level
• Each of the charts displays these number
differently
• See page 5-28
Features of constant Pressure Charts
Observational data
• Observational data can be from:
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Radiosonde observations
Weather reconnaissance aircraft
Aircraft observations on-time and on-level
Aircraft observations off-time or off-level
Satellite wind estimates
STATION DATA
• Temperature = Celsius found in the top left
hand corner
• If below 0 prefaced with a minus sign.
• Left blank if missing
• Temp/Dew Point spread - found in the
bottom right hand corner in Celsius. An “X”
is plotted when the air is extremely dry. Left
blank if missing.
STATION DATA
• Hc= constant pressure height change which
occurred during the previous 12 hours in tens
of meters.
• Example +04 = height of the surface rose 40
meters and -12 means the height fell by 120
meters
STATION DATA
• Aircraft and satellite observations are
also used as information sources for
constant pressure charts.
• A square is used to identify an aircraft
reporting position.
STATION DATA
• A star is used to identify a satellite
reporting position . Satellite information
is determined by identifying cloud drift
and height of cloud tops.
• Aircraft and satellite data are plotted on
the constant pressure chart closest to
their reporting altitudes.
Radiosond Plotting Model Examples
STATION DATA
• Variations of height are analyzed by
contours, variations of temperature by
isotherms, and variations of wind speed
by isotachs.
• Contours are lines of constant height, in meters,
which are referenced to mean sea level.
• They are used to identify and characterize pressure
systems on constant pressure charts.
STATION DATA
• Contours are drawn as solid lines and are
identified by a three-digit code located on
each contour.
• Contour patterns on constant pressure charts
can be interpreted the same as isobar patterns
on the surface chart. For example an area of
low height = area of low pressure
STATION DATA
• Isotherms= lines of equal temperature.
• An isotherm separates colder air from
warmer air. Isotherms are drawn as bold,
dashed lines on constant pressure charts.
Isotherm values are identified by a two-digit
block on each line. The two digits are
prefaced by “+ or -”.
• Drawn at 5 degree intervals on each chart.
STATION DATA
• Isotachs = lines of equal wind speed.
Isotachs separate higher wind speeds from
lower wind speeds.
• Isotachs are analyzed on the 300, 250, and
200mb chart.
• Drawn as short fine dashed lines.
• Values are identified by a two or three digit
number followed by a K on each line.
• Drawn at 20 knot intervals starting at 10KTs
STATION DATA
• Zones of very strong winds are highlighted
by hatches. Hatched and unhatched areas are
alternated at 40 knot intervals beginning at
70 knots.
• 70-110 hatched
• 110-150 not hatched
• etc….
CONSTANT PRESSURE
ANALYSIS CHART
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6 separate standard charts
850mb 5,000
700mb 10,000
500mb 18,000
300mb 30,000
250mb 34,000
200mb 39,000
850 MB approx. 5000ft
700 MB approx. 10000ft
500 MB approx. 18000ft
300 MB approx. 30000ft
200 MB approx. 39000ft
CONSTANT PRESSURE
ANALYSIS CHART
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USEFUL:
can determine areas of high winds
gives the upper air wx picture
can determine possible levels of icing
can determine the right altitude for best
wind in combination with the best wx
• look for the high and low pressure systems
of associated wx
SECTION 5.3 Freezing Level Graphics
SECTION 5.3 Freezing Level Graphics
• A freezing level chart shows the height of the 0
degree C constant-temperature surface
• ADDS
– http://adds.aviationweather.noaa.gov/icing/frzg_nav.php
• Initial analysis and forecast at 3, 6, 9 and 12 hours
in the future.
• Initial analysis and 3 hour forecast are updated
hourly. The 6, 9, 12 hour forecast are updated
every three hours.
SECTION 5.3 Freezing Level Graphics
SECTION 5.3 Freezing Level Graphics
• Regions with white indicate the surface and the
entire depth of the atmosphere are below freezing.
• Hatched regions represent areas where the surface
temps is below freezing with multiple freezing
levels aloft.
• If color change by more than one color compared
to the scale such as orange to blue this indicates
multiple freezing levels.
SECTION 5.3 Freezing Level Graphics
SECTION 5.3 Freezing Level Graphics
• Old freezing level charts can be found at
• http://weather.noaa.gov/pub/fax/QYSA00.T
IF
SECTION 5.3 Freezing Level Graphics
FREEZING LEVEL PANEL
• solid lines are Fz level in MSL and
Celsius
• every 4000 feet
• dashed line indicates 0º C isotherm
FREEZING LEVEL PANEL
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USEFUL:
Planning for icing probabilities
for locating inversions
Hazardous icing possibilities
Lifted Index Analysis Chart (no longer produced)
Lifted Index Analysis Chart
• Issued twice a day 00Z and 12Z
• http://weather.noaa.gov/pub/fax/QXUA00.T
IF
• Stability of the atmosphere up to 500 mb
(18,000ft).
• Isopleths = lines of equal lifted index are
drawn in intervals of 4 units for index
values of +4 and lower.
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Lifted Index Analysis Chart
Lifted index LI
parcel of air surface to 18,000 feet
measure adiabatic cooling
parcel would be colder + index
parcel would be warmer - index
parcel would be the same 0 index
– circles are blackened if LI is > 0
Lifted Index
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pos = stable
0 = neutral
neg = unstable
This is a theoretical type deal, the parcel of
air may not be lifted all the way up to
18,000 or there may not be enough moisture
• More useful for the severity of T storm
rather than probability they will occur
Lifted index/K index
• K index is a measure of vertical temp
lapse rate, moisture content of the lower
atmosphere, and vertical extent of the
moist layer.
• To get a large K index
– 1. Unstable lapse rate
– 2. High moisture content
– 3. High degree of saturation
• So to predict T storms, you need a neg
LI and a High K index
Lifted index/K index
Other NWS Fax products
• http://weather.noaa.gov/fax/nwsfax.html
SECTION 6 Products for
Aviation Hazards
SIGMETS
• Significant Meteorological Information
• Provides notice of potentially hazardous en
route phenomena such as TS and GR,
turbulence, icing, sand and dust storms,
tropical cyclones, and volcanic ash
• http://adds.aviationweather.noaa.gov/airmet
s/
SIGMETS
SIGMETS
SIGMETS
SIGMETS
• Valid for
– Volcanic ash or tropical cyclones for 6 hours
out look 12 hours
– All other phenomena not to exceed 4 hours
• November through Yankee, excluding
Sierra and Tango
• If phenomenon continues number changes
– Yankee 1, yankee 2
Convective SIGMETS
• Bad weather associated with TS
Convective SIGMETS
• Issued hourly + 55
• Valid for up to 2 hours
Convective SIGMETS
Convective SIGMETS
AIRMETS
• http://adds.aviationweather.noaa.gov/airmet
s/
• Sierra
• Tango
• Zulu
• Page 6-17
AIRMETS
AIRMETS
AIRMETS
• Every 6 hours
6.4 Convective Outlooks
6.4 Convective Outlooks
6.6 Volcanic Ash Advisory Products
6.6 Volcanic Ash Advisory Products
• VAAS may be issued within 6 hour of an
erruption and every 6 hours thereafter.
• Pretty plain english
– See page 6-52 and 6-54
• http://www.nationalanthems.net/windowsmedia/vocal/CA