Ch 16 – Aviation Weather Resources Section A – The Weather Forecasting Process Section A – The...

Ch 16 – Aviation Weather Ch 16 – Aviation Weather ResourcesResources


• Section A – The Weather Forecasting Section A – The Weather Forecasting ProcessProcess– Collecting Weather DataCollecting Weather Data– Processing Weather DataProcessing Weather Data– Making the ForecastMaking the Forecast

•Forecasting MethodsForecasting Methods

•Forecasting AccuracyForecasting Accuracy

Ch 16 – Aviation Weather Ch 16 – Aviation Weather ResourcesResources• Section B – Aviation Weather Forecast ProductsSection B – Aviation Weather Forecast Products

– Forecast Products in Text FormatForecast Products in Text Format•Terminal Aerodrome Forecast (TAF)Terminal Aerodrome Forecast (TAF)•Area Forecast (FA)Area Forecast (FA)•In-flight Weather Advisories (WS, WST, WA)In-flight Weather Advisories (WS, WST, WA)•Transcribed Weather Broadcasts (TWEB)Transcribed Weather Broadcasts (TWEB)•Winds and Temperatures Aloft Forecast (FD)Winds and Temperatures Aloft Forecast (FD)•Other Advisories, Watches, and WarningsOther Advisories, Watches, and Warnings


– Forecast Products in Graphic FormatForecast Products in Graphic Format

•Significant Weather Prognostic ChartSignificant Weather Prognostic Chart

•Forecast Winds and Temperatures Forecast Winds and Temperatures Aloft ChartAloft Chart


• Section C – Aviation Weather Section C – Aviation Weather Information SourcesInformation Sources– FAA Flight Service Stations (FSS)FAA Flight Service Stations (FSS)– Continuous Broadcasts of Weather Continuous Broadcasts of Weather

Information (TWEB, HIWAS)Information (TWEB, HIWAS)– Other Weather Information SourcesOther Weather Information Sources– Weather on the InternetWeather on the Internet


• Weather information and forecasts Weather information and forecasts are beneficial in numerous waysare beneficial in numerous ways– Prediction of warm temperatures or the Prediction of warm temperatures or the

change of rain helps us decide whether change of rain helps us decide whether to plan a picnic or carry an umbrella for to plan a picnic or carry an umbrella for the daythe day

– Forecasts of severe weather such as Forecasts of severe weather such as blizzards, thunderstorms, or hurricanes blizzards, thunderstorms, or hurricanes help communities prevent property help communities prevent property damage and save livesdamage and save lives


• As a pilot, weather influences your As a pilot, weather influences your life in a unique waylife in a unique way– Determinations regarding weather Determinations regarding weather

conditions must be made before every conditions must be made before every flight, and crucial weather decisions flight, and crucial weather decisions may have to be made in-flightmay have to be made in-flight


• A wide variety of weather resources are A wide variety of weather resources are available to assist you in this decision-making available to assist you in this decision-making processprocess– We describe the on-going process of We describe the on-going process of

collecting, transmitting, and processing collecting, transmitting, and processing weather data to produce a weather forecastweather data to produce a weather forecast

– We then consider various formats of We then consider various formats of aviation weather forecasts, and the sources aviation weather forecasts, and the sources of aviation weather informationof aviation weather information


• When you complete Chapter 16, you When you complete Chapter 16, you should understand how weather should understand how weather information is compiled and processed, information is compiled and processed, and some basic concepts of forecastingand some basic concepts of forecasting

• You should also be familiar with the You should also be familiar with the variety of aviation weather forecasts variety of aviation weather forecasts available to you, as well as the sources of available to you, as well as the sources of aviation weather information to help you aviation weather information to help you make safe preflight and in-flight decisionsmake safe preflight and in-flight decisions


• Section A: The Weather Forecasting Section A: The Weather Forecasting ProcessProcess– There are three important steps in the There are three important steps in the

forecasting process: data collection, data forecasting process: data collection, data processing and forecastingprocessing and forecasting•Collecting Weather DataCollecting Weather Data

– The World Meteorological Organization The World Meteorological Organization (WMO), a United Nations agency is (WMO), a United Nations agency is responsible for the standardization of responsible for the standardization of observations and the international observations and the international exchange of weather dataexchange of weather data


•Processing Weather DataProcessing Weather Data– The National Weather Service (NWS), The National Weather Service (NWS),

a part of the National Oceanic and a part of the National Oceanic and Atmospheric Administration (NOAA), Atmospheric Administration (NOAA), is the U.S. government agency that is is the U.S. government agency that is primarily responsible for gathering primarily responsible for gathering and processing meteorological data and processing meteorological data and for providing weather forecasts and for providing weather forecasts and warningsand warnings


– These continuing and complicated These continuing and complicated tasks are conducted by several NWS tasks are conducted by several NWS offices including the National Centers offices including the National Centers for Environmental Protection (NCEP) for Environmental Protection (NCEP) and local Weather Forecast Offices and local Weather Forecast Offices (WFO)(WFO)

– One of the components of the NCEP is One of the components of the NCEP is the Aviation Weather Center (AWC) the Aviation Weather Center (AWC) which specializes in the preparation of which specializes in the preparation of aviation weather informationaviation weather information


•Forecasting MethodsForecasting Methods– The most comprehensive forecast The most comprehensive forecast

technique today is numerical technique today is numerical weather prediction (NWP) which weather prediction (NWP) which solves a set of mathematical solves a set of mathematical equations (a numerical model) to equations (a numerical model) to predict the weatherpredict the weather


•Forecasting AccuracyForecasting Accuracy– In comparison to persistence In comparison to persistence

forecasts, the accuracy of forecasts, the accuracy of meteorological forecasts, which are meteorological forecasts, which are based on scientific knowledge as based on scientific knowledge as used by NWP and weather used by NWP and weather forecasters, is much better and forecasters, is much better and decreases much more slowly as the decreases much more slowly as the forecast period increasesforecast period increases


– However, for the longest forecast However, for the longest forecast periods, the accuracy of periods, the accuracy of meteorological forecasts is no meteorological forecasts is no better than that of climatological better than that of climatological forecasts, which are based purely forecasts, which are based purely on past averages and are typically on past averages and are typically not very accurate at allnot very accurate at all


– Forecasting the weather is somewhat Forecasting the weather is somewhat chaotic, which is not too far from the chaotic, which is not too far from the mark. As applied to weather forecasting, mark. As applied to weather forecasting, chaos theory describes the potential chaos theory describes the potential difficulty in making forecasts for long difficulty in making forecasts for long periods of timeperiods of time

– The science of chaos began in the early The science of chaos began in the early 1960s with a mathematician and 1960s with a mathematician and atmospheric scientist named Edward atmospheric scientist named Edward Lorenz and his exploration of computer Lorenz and his exploration of computer forecastsforecasts


• Section B: Aviation Weather Forecast Section B: Aviation Weather Forecast ProductsProducts– Decoding keys for aviation weather Decoding keys for aviation weather

forecast products are included in forecast products are included in Appendix DAppendix D

– In addition, FAA Advisory Circular 00-45 In addition, FAA Advisory Circular 00-45 Aviation Weather Services contains Aviation Weather Services contains further informationfurther information


– Selectivity – requires that you know Selectivity – requires that you know exactly what you need, what is available exactly what you need, what is available and where and when it is availableand where and when it is available

– Visualization – forming a mental image Visualization – forming a mental image of current and forecast weather of current and forecast weather conditionsconditions


• Forecast Products in Text FormatForecast Products in Text Format– Forecast products in text format include:Forecast products in text format include:

•Terminal Aerodrome Forecasts Terminal Aerodrome Forecasts (TAF)(TAF) – describes weather conditions – describes weather conditions that are expected to occur within a 5 that are expected to occur within a 5 nm radius of an airport over a 24 hour nm radius of an airport over a 24 hour period. period.


– In the US routine TAFs are issued 4 In the US routine TAFs are issued 4 times daily at 0000Z, 0600Z, 1200Z, times daily at 0000Z, 0600Z, 1200Z, and 1800Z. and 1800Z.

– The TAF is one of the most valuable The TAF is one of the most valuable sources for the predicted weather at sources for the predicted weather at a specific airport. a specific airport.

– Predicted sky condition, visibility, Predicted sky condition, visibility, weather and obstructions to vision, weather and obstructions to vision, wind direction and speed, and wind direction and speed, and expected changes during the expected changes during the forecast period can be derived from forecast period can be derived from TAFs. TAFs.


•Area Forecasts (FA)Area Forecasts (FA) – expected – expected VMC, clouds and general weather VMC, clouds and general weather conditions over an area the size of conditions over an area the size of several states are described in an several states are described in an Area Forecast (FA). Area Forecast (FA). – An FA is used to determine en-route An FA is used to determine en-route

weather, including conditions at weather, including conditions at airports that do not have terminal airports that do not have terminal forecasts. forecasts.


– An FA should always be used in An FA should always be used in conjunction with the most recent in-conjunction with the most recent in-flight weather advisories. flight weather advisories.

– Area forecasts are normally issued Area forecasts are normally issued three times daily and are valid for three times daily and are valid for 18 hours. 18 hours.


– An FA has four sections:An FA has four sections: Header – describes the source Header – describes the source

of the FA, the date and time of of the FA, the date and time of issue, the valid times and the issue, the valid times and the areas the FA coversareas the FA covers

Precautionary Statements – Precautionary Statements – describe IFR and mountain describe IFR and mountain obscurations, thunderstorm obscurations, thunderstorm hazards, and states that all hazards, and states that all heights are MSL unless heights are MSL unless otherwise notedotherwise noted


Synopsis – a brief summary Synopsis – a brief summary identifying the location and identifying the location and movement of pressure systems, movement of pressure systems, fronts, and circulation patterns fronts, and circulation patterns for the 18 hour forecast period.for the 18 hour forecast period.

VFR Clouds and Weather – this VFR Clouds and Weather – this section lists expected sky section lists expected sky condition, visibility and weather condition, visibility and weather for the next 12 hours and an for the next 12 hours and an outlook for the following 6 hoursoutlook for the following 6 hours


– Area forecasts are issued by the Area forecasts are issued by the Aviation Weather Center (AWC) for Aviation Weather Center (AWC) for the six regions in the contiguous US. the six regions in the contiguous US.

The Alaskan Aviation Weather The Alaskan Aviation Weather Unit issues an FA for the state of Unit issues an FA for the state of Alaska while the Honolulu WFO Alaska while the Honolulu WFO handles Hawaii. handles Hawaii.

Special FAs are also issued for the Special FAs are also issued for the Gulf of Mexico and international Gulf of Mexico and international airspaceairspace


– Within its prescribed area, an FA Within its prescribed area, an FA describes weather features and describes weather features and conditions relative to common conditions relative to common geographical regions and featuresgeographical regions and features


– The contiguous US is divided into 6 The contiguous US is divided into 6 forecast areas forecast areas

SFO – San FranciscoSFO – San FranciscoSLC – Salt Lake CitySLC – Salt Lake CityDFW – Dallas / Fort WorthDFW – Dallas / Fort WorthCHI – ChicagoCHI – ChicagoBOS – BostonBOS – BostonMIA – MiamiMIA – Miami


• ***The area forecast covers an area of ***The area forecast covers an area of several states and can be used to several states and can be used to determine en-route weather and determine en-route weather and conditions at your destination if no conditions at your destination if no TAF has been issuedTAF has been issued


• The geographical area designator map The geographical area designator map can be useful in determining the can be useful in determining the specific area described by an area specific area described by an area forecastforecast– The contiguous US is divided into six The contiguous US is divided into six

forecast areas (colored area)forecast areas (colored area)– You may want to keep a copy of this map You may want to keep a copy of this map

with your flight planning materials so that with your flight planning materials so that you have access to it when you obtain you have access to it when you obtain weather information.weather information.


• The accuracy of weather forecasts as The accuracy of weather forecasts as a function of the forecast period and a function of the forecast period and the forecasting methodthe forecasting method– Comparison of the accuracy of Comparison of the accuracy of

persistence, meteorological, and persistence, meteorological, and climatological forecasts for forecast climatological forecasts for forecast periods from a few hours to several daysperiods from a few hours to several days

– Very generalVery general


– The actual rate of deterioration of the The actual rate of deterioration of the accuracy of forecasts for a given airport accuracy of forecasts for a given airport depends on its location, the season, and depends on its location, the season, and the forecast variable.the forecast variable.


• In-flight Weather Advisories (WS, In-flight Weather Advisories (WS, WST, WA)WST, WA) – consist of either an observation and a consist of either an observation and a

forecast, or just a forecast for the forecast, or just a forecast for the development of potentially hazardous development of potentially hazardous weatherweather


– SIGMET (WS)SIGMET (WS) – describes conditions – describes conditions which can pose hazards to which can pose hazards to allall aircraft. aircraft. •SIGMETs are valid for up to four SIGMETs are valid for up to four

hours. hours.


•If the following phenomena are observed If the following phenomena are observed or expected to occur, a SIGMET is issuedor expected to occur, a SIGMET is issued

– 1. Severe icing not associated with 1. Severe icing not associated with thunderstormsthunderstorms

– 2. Severe or extreme turbulence or clear air 2. Severe or extreme turbulence or clear air turbulence not associated with thunderstormsturbulence not associated with thunderstorms

– 3. Dust storms or sandstorms lowering surface 3. Dust storms or sandstorms lowering surface or in-flight visibilities to below three milesor in-flight visibilities to below three miles

– 4. Volcanic ash4. Volcanic ash


• ***SIGMETs are issued as warnings of ***SIGMETs are issued as warnings of hazardous weather, such as severe hazardous weather, such as severe icing, which is of operational interest icing, which is of operational interest to all aircraftto all aircraft


– Convective SIGMETs (WST)Convective SIGMETs (WST) – describes – describes convective activity that is convective activity that is potentially potentially hazardous to all categories of aircrafthazardous to all categories of aircraft


•Convective SIGMETs (WST)Convective SIGMETs (WST) – describes – describes convective activity that is convective activity that is potentially potentially hazardous to all categories of aircrafthazardous to all categories of aircraft– Bulletins are issued hourly with special Bulletins are issued hourly with special

advisories issued as requiredadvisories issued as required– The forecast period for a WST is two The forecast period for a WST is two

hours or lesshours or less– Criteria for issuance are any of the Criteria for issuance are any of the

following conditionsfollowing conditions


– Severe thunderstorms (surface Severe thunderstorms (surface winds greater than or equal to 50 winds greater than or equal to 50 knots and/or hail at the surface knots and/or hail at the surface greater than or equal to ¾ inches in greater than or equal to ¾ inches in diameter and/or tornadoes)diameter and/or tornadoes)

– Embedded thunderstormsEmbedded thunderstorms– A line of thunderstormsA line of thunderstorms


– Thunderstorms producing Thunderstorms producing precipitation with an intensity precipitation with an intensity greater than or equal to heavy and greater than or equal to heavy and affecting 40% or more of an area at affecting 40% or more of an area at least 3,000 square milesleast 3,000 square miles


– Convective SIGMET bulletins are Convective SIGMET bulletins are issued for the Eastern (E), Central issued for the Eastern (E), Central (C), and Western (W) United States(C), and Western (W) United States

– Convective SIGMET text is Convective SIGMET text is presented in figure 16-7presented in figure 16-7


• AIRMET (WA)AIRMET (WA) – issued for significant – issued for significant weather at intensities weather at intensities lower than those lower than those required for the issuance of a SIGMETrequired for the issuance of a SIGMET– Although AIRMETs are of operational Although AIRMETs are of operational

interest to all aircraft, the weather interest to all aircraft, the weather conditions specified are particularly conditions specified are particularly hazardous to light aircraft having limited hazardous to light aircraft having limited capability or minimal equipment and capability or minimal equipment and instrumentationinstrumentation


– There are three different AIRMETsThere are three different AIRMETs

•AIRMET SierraAIRMET Sierra – describes IFR conditions – describes IFR conditions and/or extensive mountain obscurationsand/or extensive mountain obscurations

•AIRMET TangoAIRMET Tango – describes areas of – describes areas of moderate turbulence, sustained surface moderate turbulence, sustained surface winds in excess of 30 knots and areas of winds in excess of 30 knots and areas of non-convective low-level wind shearnon-convective low-level wind shear

•AIRMET ZuluAIRMET Zulu – describes moderate icing – describes moderate icing and provides freezing level heightsand provides freezing level heights


– Pilots with limited experience or Pilots with limited experience or qualifications should pay special qualifications should pay special attention to these advisoriesattention to these advisories


– AIRMETs are issued every six hours with AIRMETs are issued every six hours with unscheduled updates and corrections unscheduled updates and corrections issued as necessaryissued as necessary

– Each bulletin contains any current Each bulletin contains any current AIRMETs that are in effect, an outlook for AIRMETs that are in effect, an outlook for weather that is expected after the AIRMET weather that is expected after the AIRMET valid period and any significant conditions valid period and any significant conditions that do not meet AIRMET criteriathat do not meet AIRMET criteria

– Examples of AIRMETs Sierra, Tango and Examples of AIRMETs Sierra, Tango and Zulu are given in figure 16-8Zulu are given in figure 16-8


• ***Weather conditions that are ***Weather conditions that are particularly hazardous to small, particularly hazardous to small, single-engine aircraft are contained single-engine aircraft are contained in an AIRMETin an AIRMET


– AIRMETs and SIGMETs are issued for the AIRMETs and SIGMETs are issued for the 6 regions corresponding to the FA areas6 regions corresponding to the FA areas

– These widespread advisories must be These widespread advisories must be either affecting or forecasted to affect at either affecting or forecasted to affect at least 3,000 square miles at any one timeleast 3,000 square miles at any one time

– International SIGMETs are issued International SIGMETs are issued worldwide by ICAO Meteorological worldwide by ICAO Meteorological Watch Offices (MWOs); see figure 16-9Watch Offices (MWOs); see figure 16-9


– The criteria for International SIGMETs are The criteria for International SIGMETs are broader than the criteria for either WS or broader than the criteria for either WS or WST for the USWST for the US•Thunderstorms in lines, embedded in Thunderstorms in lines, embedded in

clouds, or in large areas producing clouds, or in large areas producing tornadoes or large hailtornadoes or large hail

•Tropical cyclonesTropical cyclones•Severe icingSevere icing•Severe or extreme turbulenceSevere or extreme turbulence•Dust storms or sand storms lowering Dust storms or sand storms lowering

visibility to less than 3 miles (5 km)visibility to less than 3 miles (5 km)•Volcanic Ash Volcanic Ash


– Transcribed Weather Broadcasts Transcribed Weather Broadcasts (TWEB)(TWEB)

•A Transcribed Weather Broadcasts A Transcribed Weather Broadcasts (TWEB) is a synopsis and forecast for (TWEB) is a synopsis and forecast for a 50-mile-wide corridor along a a 50-mile-wide corridor along a specific flight route or within 50 nm specific flight route or within 50 nm of the FSSof the FSS

•TWEBs are prepared for more than TWEBs are prepared for more than 200 flight routes and local vicinities 200 flight routes and local vicinities around the USaround the US


•TWEB forecasts are valid for 12 TWEB forecasts are valid for 12 hourshours

•They are updated 4 times dailyThey are updated 4 times daily

•TWEBs do not include areas of TWEBs do not include areas of icing and turbulenceicing and turbulence

•TWEB example given in figure 16-TWEB example given in figure 16-1010

Ch 16 – Aviation Weather Ch 16 – Aviation Weather ResourcesResources• Winds and Temperatures Aloft Winds and Temperatures Aloft

Forecasts (FD)Forecasts (FD) – FDs furnish a prediction of wind speed (knots), FDs furnish a prediction of wind speed (knots),

wind direction (degrees True), and temperature wind direction (degrees True), and temperature (degrees C) for selected altitudes at specific (degrees C) for selected altitudes at specific locations across the US, including Alaska, Hawaii locations across the US, including Alaska, Hawaii and over some US coastal watersand over some US coastal waters

– Figure 16-11 gives the distribution of forecast Figure 16-11 gives the distribution of forecast stationsstations

– Winds and temperatures aloft contain wind Winds and temperatures aloft contain wind direction in relation to true north, wind speed in direction in relation to true north, wind speed in knots and temperature in degrees Celsius for a knots and temperature in degrees Celsius for a range of altitudesrange of altitudes


– FDs wind speeds between 100 and 199 FDs wind speeds between 100 and 199 knots are encoded so direction and speed knots are encoded so direction and speed can be represented by four digitscan be represented by four digits

– These winds are decoded by subtracting 50 These winds are decoded by subtracting 50 from the two digit wind direction and adding from the two digit wind direction and adding 100 to the wind speed100 to the wind speed

– The negative sign for temperatures above The negative sign for temperatures above 24,000 feet MSL is not included24,000 feet MSL is not included

– A wind code of 9900 is interpreted as light A wind code of 9900 is interpreted as light and variableand variable

– Forecast winds greater than or equal to 199 Forecast winds greater than or equal to 199 knots are reported as 199 knotsknots are reported as 199 knots

Ch 16 – Aviation Weather Ch 16 – Aviation Weather ResourcesResources• Other Advisories, Watches, and WarningsOther Advisories, Watches, and Warnings

– Center Weather Service Unit (CWSU) – Center Weather Service Unit (CWSU) – operated by NWS meteorologists within the operated by NWS meteorologists within the confines of each ARTCCconfines of each ARTCC

– Meteorological impact statements (MIS) / Meteorological impact statements (MIS) / center weather advisories (CWA) – produced by center weather advisories (CWA) – produced by the CWSU of each ARTCCthe CWSU of each ARTCC

– Hurricane advisories (WH) – issued to alert the Hurricane advisories (WH) – issued to alert the aviation community to the presence of a aviation community to the presence of a hurricane located at least 300 nm offshore and hurricane located at least 300 nm offshore and threatening the coastlinethreatening the coastline


– Severe watch bulletin (WW) – an unscheduled message Severe watch bulletin (WW) – an unscheduled message that defines areas of possible severe thunderstorms or that defines areas of possible severe thunderstorms or tornado activitytornado activity

– Severe watch alert (AWW) – a preliminary notice to alert Severe watch alert (AWW) – a preliminary notice to alert forecasters, briefers and pilots that WW is being issuedforecasters, briefers and pilots that WW is being issued

– Severe thunderstorm warnings / tornado warnings – Severe thunderstorm warnings / tornado warnings – public notifications that those phenomena have been public notifications that those phenomena have been sighted visually or by radarsighted visually or by radar

– Convective outlook (AC) – SPC also produces a Convective outlook (AC) – SPC also produces a convective outlook (AC) for the occurrence of convective outlook (AC) for the occurrence of thunderstorms (non-severe and severe) five times a day thunderstorms (non-severe and severe) five times a day for the next 24 hours (day 1 convective outlook) and for the next 24 hours (day 1 convective outlook) and twice a day for the following 24 hours (day 2 convective twice a day for the following 24 hours (day 2 convective outlook)outlook)


• Forecast Products in Graphic FormatForecast Products in Graphic Format – Descriptions of examples of all common Descriptions of examples of all common

forecast and analysis graphics are given forecast and analysis graphics are given in Appendix Din Appendix D


• Significant Weather Prognostic ChartSignificant Weather Prognostic Chart – The The significant weather prognostic chartsignificant weather prognostic chart can can

be used to determine areas to avoid, such as be used to determine areas to avoid, such as forecast locations of low visibilities or turbulenceforecast locations of low visibilities or turbulence

– See figure 16-13See figure 16-13– Lower left hand corner of each panel gives the Lower left hand corner of each panel gives the

valid times for the forecastvalid times for the forecast– The surface prog in the lower panel uses The surface prog in the lower panel uses

standard symbols to depict fronts, isobars, standard symbols to depict fronts, isobars, pressure centers and areas of forecast pressure centers and areas of forecast precipitationprecipitation


– Regions of continuous precipitation and Regions of continuous precipitation and unstable showery precipitation are unstable showery precipitation are within a solid green line with hatchingwithin a solid green line with hatching

– Intermittent precipitation is only Intermittent precipitation is only enclosed with a solid green lineenclosed with a solid green line

– The upper panel portrays forecast areas The upper panel portrays forecast areas of IFR (solid red lines)of IFR (solid red lines)


– MVFR (scalloped green lines)MVFR (scalloped green lines)– VFR conditionsVFR conditions– Areas and layers of expected moderate Areas and layers of expected moderate

or greater turbulence are enclosed with or greater turbulence are enclosed with dashed yellow linesdashed yellow lines

– The highest freezing level (dashed green The highest freezing level (dashed green lines) and the intersection of the lines) and the intersection of the freezing level with the surface are also freezing level with the surface are also shownshown

Ch 16 – Aviation Weather Ch 16 – Aviation Weather ResourcesResources• High-level significant weather prog chartHigh-level significant weather prog chart

– Covers the airspace from 25,000 feet to 60,000 feet Covers the airspace from 25,000 feet to 60,000 feet pressure altitudepressure altitude

– Charts from some world area forecast centers (WAFC) Charts from some world area forecast centers (WAFC) cover the layer from FL240 to FL630cover the layer from FL240 to FL630

– A wide range of information can be interpreted from this A wide range of information can be interpreted from this chart including forecast of thunderstorm areas, tropical chart including forecast of thunderstorm areas, tropical cyclones, surface positions of well-defined convergence cyclones, surface positions of well-defined convergence zones, movement of frontal systems and the locations zones, movement of frontal systems and the locations and speeds of jetstreams; see figure 16-14and speeds of jetstreams; see figure 16-14

– The positions of jet streams with speeds greater than 80 The positions of jet streams with speeds greater than 80 knots are indicated by long, heavy lines with arrowheads knots are indicated by long, heavy lines with arrowheads showing the direction of flowshowing the direction of flow


– Each jet is labeled with altitude; speed and Each jet is labeled with altitude; speed and direction of the maximum wind in the jet direction of the maximum wind in the jet core is shown with conventional wind barbscore is shown with conventional wind barbs

– Heights of the tropopause are indicated in Heights of the tropopause are indicated in boxes; relatively high and low tropopause boxes; relatively high and low tropopause heights are indicated with H and L heights are indicated with H and L respectivelyrespectively

– Areas of significant CB (thunderstorm) Areas of significant CB (thunderstorm) activity are enclosed in scallooed lines with activity are enclosed in scallooed lines with heights of tops and bases indicatedheights of tops and bases indicated


– If the base of the layer is below 25,000 feet it If the base of the layer is below 25,000 feet it is indicated by xxxis indicated by xxx

– These areas include CB embedded in clouds, These areas include CB embedded in clouds, haze, or dusthaze, or dust

– Areas of moderate and greater turbulence Areas of moderate and greater turbulence are enclosed in dashed linesare enclosed in dashed lines

– Predicted intensities and heights of bases and Predicted intensities and heights of bases and tops of the turbulent layers are also giventops of the turbulent layers are also given

– The high-level significant weather prog chart The high-level significant weather prog chart also includes positions of surface fronts, also includes positions of surface fronts, squall lines and the location of volcanic squall lines and the location of volcanic eruptions; see Appendix D for more detailseruptions; see Appendix D for more details


• Forecast Winds and Temperatures Forecast Winds and Temperatures Aloft ChartAloft Chart– The third forecast graphic that is The third forecast graphic that is

useful for flight planning is the useful for flight planning is the forecast winds and temperatures forecast winds and temperatures aloft chartaloft chart

– This is simply a graphical This is simply a graphical presentation of the information presentation of the information given in FD forecast bulletinsgiven in FD forecast bulletins


– See figure 16-15 for a sample FD See figure 16-15 for a sample FD chart for international flightschart for international flights

– Wind and temperature predictions Wind and temperature predictions are produced at regularly spaced are produced at regularly spaced latitude and longitude positions on latitude and longitude positions on international chartsinternational charts

– Other useful forecast charts include Other useful forecast charts include the convective outlook chart and the convective outlook chart and the volcanic ash forecast transport the volcanic ash forecast transport and dispersion (VAFTAD) chartand dispersion (VAFTAD) chart


• Section C: Aviation Weather Section C: Aviation Weather Information SourcesInformation Sources


• FAA Flight Service Stations (FSS)FAA Flight Service Stations (FSS) – The flight service station (FSS) is one of the The flight service station (FSS) is one of the

most common sources of weather information most common sources of weather information for pilotsfor pilots

– Automated flight service stations (AFSS) – Automated flight service stations (AFSS) – about one per state; these are the result of about one per state; these are the result of consolidating older, manual stationsconsolidating older, manual stations

– More aviation weather briefing services are More aviation weather briefing services are provided by FAA flight service stations than provided by FAA flight service stations than any other government serviceany other government service


– A A standard briefingstandard briefing – provides you with the – provides you with the most complete weather picture tailored to your most complete weather picture tailored to your specific flight; figure 16-16 lists the items specific flight; figure 16-16 lists the items included in a standard briefingincluded in a standard briefing

– For a telephone briefing it is helpful to have For a telephone briefing it is helpful to have examined these data ahead of timeexamined these data ahead of time

– An An abbreviated briefingabbreviated briefing – enables you to – enables you to supplement mass disseminated data, update a supplement mass disseminated data, update a previous briefing, or request specific informationprevious briefing, or request specific information

– If your proposed departure time is six or more If your proposed departure time is six or more hours in the future an hours in the future an outlook briefingoutlook briefing provides provides a general overview of forecasted weathera general overview of forecasted weather


– The most common method of obtaining The most common method of obtaining weather information from an FSS is a weather information from an FSS is a briefing over the telephonebriefing over the telephone

– You can obtain one of three types of You can obtain one of three types of briefings: standard, abbreviated and briefings: standard, abbreviated and outlookoutlook

– An FSS briefing can be obtained by An FSS briefing can be obtained by dialing 1-800-WX-BRIEFdialing 1-800-WX-BRIEF


• ***You should request a standard ***You should request a standard briefing if you have received no briefing if you have received no preliminary weather information and are preliminary weather information and are departing within the hour. departing within the hour. – To supplement mass disseminated To supplement mass disseminated

data, an abbreviated briefing should data, an abbreviated briefing should be requested. be requested.

– The FSS provides an outlook briefing 6 The FSS provides an outlook briefing 6 or more hours in advance of your or more hours in advance of your proposed departure timeproposed departure time


– Transcribed information briefing service (TIBS) Transcribed information briefing service (TIBS) – an AFSS service that provides continuous – an AFSS service that provides continuous telephone recordings of meteorological and/or telephone recordings of meteorological and/or aeronautical information 24 hours a dayaeronautical information 24 hours a day

– TIBS provides route briefings and depending on TIBS provides route briefings and depending on user demand aviation weather observations, user demand aviation weather observations, forecasts and wind and temperature aloft forecasts and wind and temperature aloft forecastsforecasts

– TIBS information is frequently updated to TIBS information is frequently updated to ensure current and accurate weather dataensure current and accurate weather data


– Local numbers for TIBS are available in Local numbers for TIBS are available in the AFD (Airport Facility Directory)the AFD (Airport Facility Directory)

– En route flight advisory service (EFAS) – En route flight advisory service (EFAS) – probably the most familiar inflight probably the most familiar inflight service to pilotsservice to pilots

– To use this service contact the specific To use this service contact the specific EFAS by using the words “Flight Watch”EFAS by using the words “Flight Watch”


– The frequency for flight watch below 18,000 feet The frequency for flight watch below 18,000 feet MSL is 122.0 MHzMSL is 122.0 MHz

– Upon your request, the flight watch specialist can Upon your request, the flight watch specialist can provide aviation weather information and time-provide aviation weather information and time-critical enroute assistancecritical enroute assistance

– If you are facing hazardous or unknown weather If you are facing hazardous or unknown weather conditions, EFAS may recommend alternate or conditions, EFAS may recommend alternate or diversionary routesdiversionary routes

– The receipt and rapid dissemination of pilot The receipt and rapid dissemination of pilot weather reports is a primary responsibility of weather reports is a primary responsibility of EFASEFAS


• ***At altitudes below 18,000 feet, you ***At altitudes below 18,000 feet, you can contact Flight Watch on 122.0 can contact Flight Watch on 122.0 MHz for information regarding MHz for information regarding current weather along your proposed current weather along your proposed route of flightroute of flight


• Continuous Broadcasts of Weather Continuous Broadcasts of Weather Information (TWEB, HIWAS)Information (TWEB, HIWAS)– TWEB is aired continuously TWEB is aired continuously

•over selected low and medium over selected low and medium frequency NDBs (nondirectional frequency NDBs (nondirectional beacons)beacons)– 190 – 535 kHz 190 – 535 kHz

•and over VORs (very high frequency and over VORs (very high frequency omni-directional ranges) omni-directional ranges) – 108.0 – 117.95 MHz108.0 – 117.95 MHz


• ***TWEBs contain in-flight cross-***TWEBs contain in-flight cross-country weather information country weather information including winds and temperatures including winds and temperatures aloft forecastsaloft forecasts


• Hazardous inflight weather advisory Hazardous inflight weather advisory service (HIWAS) service (HIWAS) – another in-flight service that provides a another in-flight service that provides a

continuous broadcast over selected continuous broadcast over selected VORs to inform you of hazardous flying VORs to inform you of hazardous flying conditions such as turbulence, icing, IFR conditions such as turbulence, icing, IFR conditions and high windsconditions and high winds


• Other Weather Information SourcesOther Weather Information Sources– Automatic terminal information service Automatic terminal information service

(ATIS) – available at most major airports (ATIS) – available at most major airports that have operational control towersthat have operational control towers

– ATIS is a pre-recorded report, broadcast ATIS is a pre-recorded report, broadcast on a dedicated frequency which includes on a dedicated frequency which includes information regarding current weather information regarding current weather and pertinent local airport conditionsand pertinent local airport conditions

– ATIS is normally recorded every hour ATIS is normally recorded every hour but may be updated any time but may be updated any time


– ATIS frequencies are listed in the AFD ATIS frequencies are listed in the AFD (Airport Facility Directory)(Airport Facility Directory)

– Direct user access terminal service Direct user access terminal service (DUATS) – The FAA supports the DUATS (DUATS) – The FAA supports the DUATS serviceservice

– This computer-based program provides This computer-based program provides NWS and FAA products that are normally NWS and FAA products that are normally used in pilot weather briefingsused in pilot weather briefings

– By using a personal computer and By using a personal computer and modem you can access weather modem you can access weather information prior to flightinformation prior to flight


– Flight plans can also be filed and Flight plans can also be filed and amended through DUATSamended through DUATS

– Other weather sources include weather Other weather sources include weather forecasts by local news broadcasts, the forecasts by local news broadcasts, the Weather Channel, airing on cable Weather Channel, airing on cable television and Jeppesen DataPlantelevision and Jeppesen DataPlan


• Weather on the InternetWeather on the Internet – The internet is probably one of the The internet is probably one of the

fastest growing sources of aviation fastest growing sources of aviation weatherweather

– Appendix F gives a large number of US Appendix F gives a large number of US and international agencies that provide and international agencies that provide both aviation weather information and both aviation weather information and general weather informationgeneral weather information


• SummarySummary– This chapter has provided an This chapter has provided an

understanding of the procedures used to understanding of the procedures used to collect and process raw weather data, collect and process raw weather data, and to make weather forecasts.and to make weather forecasts.

– The discussion of forecast methods has The discussion of forecast methods has given you some insight into the given you some insight into the accuracy of forecastsaccuracy of forecasts


– This knowledge should assist you in This knowledge should assist you in interpreting and effectively using weather interpreting and effectively using weather data for flight planning.data for flight planning.

– In addition, you are now familiar with the In addition, you are now familiar with the essential aviation weather forecast essential aviation weather forecast products in both text and graphic formatsproducts in both text and graphic formats

– You know of a variety of sources from You know of a variety of sources from which you can obtain observations and which you can obtain observations and forecasts appropriate for your flying needsforecasts appropriate for your flying needs


• The “standard briefing” is a useful guide The “standard briefing” is a useful guide in selecting pertinent informationin selecting pertinent information– Your knowledge of the three-dimensional Your knowledge of the three-dimensional

structure and behavior of weather systems structure and behavior of weather systems allows you to integrate available allows you to integrate available information into a comprehensive pictureinformation into a comprehensive picture

– This new information will help you practice This new information will help you practice “selectivity” and “visualization” in dealing “selectivity” and “visualization” in dealing with current and forecast flight weather. with current and forecast flight weather.


– A practical application of your A practical application of your knowledge of aviation weather knowledge of aviation weather resources is explored in the final chapterresources is explored in the final chapter

Ch 16 – Aviation Weather Resources Section A – The Weather Forecasting Process Section A – The...

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Transcript of Ch 16 – Aviation Weather Resources Section A – The Weather Forecasting Process Section A – The...