Transcript Weather Charts - Bob's Flight Operations Pages

Weather Charts
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Current Weather Products
• Observations
– Surface Analysis Charts
– Constant Pressure Charts
– Weather Depiction Charts
– Lifted Index Charts
– Radar Summary Charts
• Forecast Charts
– Short Range Surface Prognostic Chart
– Low level Significant Weather Prognostic Chart
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Surface Analysis Chart
• Shows the “big picture” – helps plan flights
around WX
• Depicts
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Sea level pressure
Position of highs, lows, ridges and troughs
Position of fronts
Position of boundaries
Overview of winds, temperatures and dew points
• Issued every 3 hours
• Valid for 6 hours
• Available at: http://www.hpc.ncep.noaa.gov/html/sfc2.shtml
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Surface Analysis Chart
Low
Sea Level
Pressure
–4mb interval
lines
- Line below # is
pressure trend
Warm
front
stationary
front
Cold
front –
Pips show
direction of
movement
High - Number
adjacent is central
pressure
Sea Level pressure
Tropical wave
(first 10 or 9 digits omitted)
Wind
Data
Temp
or ceiling height
Sky cover – If station
Dew Point
symbol is square then
automated data was used
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Surface Analysis Chart
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Surface Analysis Chart
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Surface Analysis Chart
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DUATS Surface Analysis Chart
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Constant Pressure Charts
• Similar to the surface analysis chart but at
different pressure levels (altitudes will vary)
– 850 MB chart ≈ 5,000’
– 700 MB chart ≈ 10,000’
– 500 MB chart ≈ 18,000’
• Provides a 3D view of large areas – interpolate
between charts
• Data gathered through balloons
• Shows winds and temps – can identify jet stream
/ freezing risks for example
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Charts available at: http://aviationweather.gov/std_brief/
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Constant Pressure Charts
X Marks
high/low
center
Issue
date/time
Wind
Level
Contour line area of = height in meters
Some charts also show:
isotherms – areas of equal temperature – bold
dashed line
isotachs – constant wind speed areas – short fine
dashed line with __K
(850 MB omits 1 before and 700 omits 2 or 3 before –
which ever makes the number closer to 3,000 meters) e.g.
309 = 3309 meters or 10,754’ – Look at gradients - wind
speed proportional to gradients (close = high winds).
Contours can be interpreted in the same manner as isobars
on the surface chart (e.g. high altitude=high pressure area) 10
Historic (FAA) Constant Pressure Chart
Wind
Temp
Temp –
DP
spread
Height / pressure altitude
Height
change /
aircraft
type
Balloon /
Ground
station
Data
Airplane
observation
Longitude
Latitude
Satellite
data
Temp /
Isotherm
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Duats Constant Pressure Chart
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Weather Depiction Chart
• Broad overview of flying conditions – IFR
(<3sm vis;1,000’), MVFR (3 to 5sm vis;1k to 3k
ceiling), VFR (>5sm vis; >3,000 ceiling)
• Also shows fronts and troughs (except 10 and
23Z)
• Prepared 8 X per day
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Weather Depiction Chart
IFR
MVFR
Precipitation
/ Vis
obstructions
Sky
cover
AGL
cloud
height
Data
Legend
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Weather depiction Chart Symbols
NB: Symbols are the same
as the Surface Analysis
Chart
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DUATS Weather Depiction Chart
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Radar Summary Chart
• Aids in preflight planning by identifying general
areas and movement of precipitation and/or
thunderstorms
• Issued hourly
• Shows:
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Radar echos
Types of precipitation
Movement of cells
Tops of precipitation
Severe Thunderstorm and Tornado Watch areas
DOES NOT SHOW clouds or fog
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Radar Summary Chart
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Radar Summary Chart
• Individual cell movement is indicated by an arrow with the
speed in knots entered as a number at the top of the arrow
head.
• Highest echo height in the area is shown above a short line,
with the top height displayed.
• Severe weather watch areas are outlined by heavy dashed
lines, usually in the form of a large rectangular box.
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NWS Radar Summary Chart
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Nexrad Radar
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Lifted Index Chart
• Provides plot of the lifted index and K index values
– Lifted Index
• is a measure of atmospheric stability – it is a comparison of
predicted temperature change from the surface (2° saturated or 3°
unsaturated) less actual temperature change from the surface to
500mb (18,000 msl +/-)
• Positive LI – colder so stable air
• Negative LI – warmer so less stable
• Zero LI – neutral stability
• Becomes more stable with decreased dew point, decreasing
surface temperature or increasing 500 mb temperature
• Severe thunderstorm guide 0 to -2 weak potential; -3 to -5
moderate potential; ≤-6 Strong potentia;
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Lifted Index Chart
– K Index – used mostly by meteorologists
• During warm season a large Ki indicates conditions
favorable for thunderstorms
• In winter temperature terms completely dominate K
index
• Ki < 20 – No chance of thunderstorms
• Ki 20 to 25 – Isolated thunderstorms
• Ki 26 – 30 – Widely scattered thunderstorms
• Ki 31 – 35 – Scattered Thunderstorms
• Ki > 35 – Numerous thunderstorms
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Lifted Index Chart
Lifted Index (LI)
Severe Potential
K-Index *
Airmass
Thunderstorm
Probability
0 to -2
Weak
<15
near 0%
15-20
20%
21-25
21-40%
26-30
41-60%
31-35
61-80%
36-40
81-90%
>40
near 100%
-3 to -5
< -6
Moderate
Strong
It is essential to note that an unstable Lifted Index does NOT automatically mean
thunderstorms. Look at the synoptic situation and if thunderstorms are expected to
develop in the unstable air, this table may be used. * Use caution when applying these
values in the western mountainous terrain due to elevation
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Lifted Index Chart
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Short Range Surface Prognostic Chart
• Surface forecast of pressure systems, fronts
and precipitation for two day period – 12, 24,
36 and 48 hours
• Uses Surface Analysis chart symbols
• Produced 4 x day for 12 and 24 hour periods;
twice per day for 36 and 48 hour periods
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Short Range Surface Prognostic Chart
Shading = >50%
coverage;
Unshaded
precip indicates
30 to 50%
coverage
A bold, dashed,
grey line is used
to separate
precipitation
within an
outlined area
with contrasting
characteristics
Precipitation
Trough
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Short Range Surface Prognostic Chart
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DUATS Low Level Weather Prognostic
Chart
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Low Level Significant Weather
Prognostic Chart
• Forecast of aviation weather hazards
• Preflight use
• 3 versions (High level (FL250-FL630); mid level (FL100FL450) and low level (SFC-FL240))
• 12 and 24 hour panels; additional charts for 30, 36 and 48
hours
• Depicts
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VFR, MVFR and IFR areas (top panel)
Freezing levels (top panel)
Turbulence (top panel)
Fronts and pressure systems (lower panel)
Available at: http://aviationweather.gov/products/swl/
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Low Level Significant Weather
Prognostic Chart
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Low Level Significant Weather
Prognostic Chart
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Low Level Significant Weather
Prognostic Chart
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DUATS Severe Weather Outlook
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DUATS Winds Aloft Forecast Chart
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NWC AirMet / Sigmet Charts
Airmet Sierra IFR
Airmet Zulu Icing
Airmet Tango Turbulence
Freezing levels
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Freezing Level Chart
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Icing
SLD (supercooled large
drop - includes
freezing drizzle
and freezing
rain).
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Turbulence
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Infrared Satellite Chart
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Visible Satellite Chart
Day
Night
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