Weather Information Summary
TEXT Current
METAR
Aviation Routine Weather Report
Hourly
SPECI- indicates significant change in one or more elements
Obtained from weather forecast office (on the ground or AFSS (en route)
UA
Pilot Report
As available
Best way to determine observed weather between reporting stations
Radar Weather Report
Indicates location of precipitation, type of precipitation, intensity and trend
TEXT Forecast
TAF
Terminal Aerodrome Forecast
Scheduled four times daily (0000Z, 0600Z, 1200Z and 1800Z)
Valid for 24-hours
Obtained from weather forecast office (on the ground or AFSS (en route)
FA
Aviation Area Forecast
Issued three times per day and amended as needed
General weather conditions over an area the size of several states
Used to interpolate weather between TAF reporting stations
WA, WS, WST
In-flight Weather Advisories
Forecasts for potentially hazardous flying conditions for en route aircraft
AIRMETs and SIGMETs are broadcast upon receipt and at 30-minute intervals
CONVECTIVE SIGMETs are issued hourly or as received
AIRMETs (WA)
Contain information on weather that may be hazardous to single engine, light aircraft, and
VFR pilots. Moderate icing or turbulence, sustained winds of 30 knots or more at the surface.
Widespread IFR and mountain obscurement
SIGMETs (WS)
Advise of weather potentially hazardous to all aircraft. Severe ore extreme turbulence,
widespread sandstorms, dust storms or volcanic ash lowering visibility to less than 3 miles.
CONVECTIVE SIGMETs (WST)
Cover weather developments such as torndoes, lines of thunderstorms, embedded
thunderstorms, severe or greater turbulence, severe icing or low level wind shear.
FB
Winds and Temperature Aloft Forecast
Four digit code: Winds (True North Knots), Temperatures (C)
Shown at nine levels from 3,000 to 39,000 feet
Temperatures above 24,00 feet are always negative
GRAPHICAL Current
Radar Summary Chart
35 minutes past each hour
Depicts the location of precipitation as well as direction and speed of movement of echoes.
Individual thunderstorm cells and lines of thunderstorms
Observed Winds Aloft Chart
Shows wind direction, speed and temperature
Pennant is 50 knots
each barb is 10 knots
each half barb is 5 knots
Weather Depiction Chart
Issued every three hours at the time shown on the chart
VFR MVFR or IFR at the valid time of the chart
Surface Analysis Chart
Issued every three hours at the time shown on the chart
AKA Surface weather analysis chart
Frontal positions
Pressure patterns
Temperature
Dew point
Wind (isobar lines)
Weather
Obstructions to vision
Constant Pressure Chart
Winds and Temperature aloft
Upper air weather map, information provide at specific pressure-level on the chart
Temperature/dew point spread
Wind height of the pressure surface
Height changes over the previous 12-hour period
Composite Moisture Stability Chart
Uses observed upper air data
Issued twice daily with valid times of 12Z and 00Z
Four panel chart:
1. Freezing level
2. Precipitable water
3. Average relative humidity
4. Stability (LI / K)
Stability panel contains lifted index (LI) and K index (K)
LI (Lifted index) The difference found by subtracting the temperature of a parcel of air theoretically
lifted from the surface to 500 millibars (18K) and the existing temperature at 500 millibars. Smaller or
negative numbers indicate unstable air good for soaring
K (K index) Examines the temperature and moisture profile.
K Index = (850) mb temp.- 500 mb temp) + (850 mb dew point) - (700 mb temp to dew point spread)
GRAPHICAL Forecast
Tropopause Height/Vertical Wind Shear Prognostic Chart
Available once per day at 18Z
Two panel chart: Maximum wind prognostic and Vertical wind shear prognostic
Shows pressure and wind at the tropopause
The minimum vertical wind shear value critical for moderate or greater turbulence is 6 knots/1,000 FT
Significant Weather Prognostics
Low-Level significant weather prognostic chart (surface to 24,000)
Shows visibility, ceilings, turbulence and icing (freezing levels)
Issued t 0000Z, 0600Z, 1200Z and 1800Z
Four panel chart
Lower two panels show 12 hour and 24 hour forecast for surface
Upper two panels show 12 hour and 24 hour forecast for from the surface to 24,000 FT
SERVICES
EFAS
En Route Flight Advisory Service
AKA Flight Watch on 122.0