PHAK 13: Aviation Weather Services Flashcards
Observations
The four types of weather observations.
- Surface
- Upper air
- Radar
- Satellite
What does AWOS stand for?
Automated Weather Observing System
What does ASOS stand for?
Automated Surface Observing System
What are ASOS and AWOS?
Continuous broadcasts of weather conditions by a computer.
Reports include date, time, wind direction and speed, visibility, sky condition, temperature, dew point, and altimeter setting.
What does RVR stand for?.
Runway visual range
Surface observations information includes…
Type of report, station identifier, date and time, modifier (as required), wind, visibility, runway visual range (RVR), weather phenomena, sky condition, temperature/dew point, altimeter reading, and applicable remarks.
What does ARTCC stand for?
Air Route Traffic Control Center
What does ARTCC do?
Maintains separation between flights conducted under IFR in the en route structure.
What does ARSR stand for?
Air Route Surveillance Radar
What does ATC stand for?
Air Traffic Control
Methods by which upper air weather phenomena can be observed.
Radiosonde observations, pilot weather reports (PIREPs), Aircraft Meteorological Data Relay (AMDAR) and the Meteorological Data Collection and Reporting System (MDCRS)
What is a radiosonde?
Small cubic instrumentation package that is suspended below a six foot hydrogen- or helium-filled balloon. Once released, the balloon rises at a rate of approximately 1,000 feet per minute (fpm). As it ascends, the instrumentation gathers various pieces of data, such as air temperature, moisture, and pressure, as well as wind speed and direction. Once the information is gathered, it is relayed to ground stations via a 300 milliwatt radio transmitter.
What does AMDAR stand for?
Aircraft Meteorological Data Relay
What is AMDAR?
An international program utilizing commercial aircraft to provide automated weather observations.
What does ACARS stand for?
Aircraft Communications Addressing and Reporting System
What does ASDAR stand for?
Aircraft to Satellite Data Acquisition and Relay
What does MDCRS stand for?
Meteorological Data Collection and Reporting System
What is MCDRS?
This program collects and disseminates real-time upper-air weather observations from
participating airlines in the U.S.A.
What does ARINC stand for?
Aeronautical Radio, Inc.
What does BUFR stand for?
Binary Universal Form
What does ESRL stand for?
Earth Science Research Laboratory
What does FDAMS stand for?
Flight Data Acquisition and Monitoring System
What does TWDR stand for?
Terminal Doppler Weather Radar
The four types of radars which provide information about precipitation and wind.
- WSR-88D NEXRAD radar AKA Doppler radar.
- FAA terminal Doppler weather radar (TDWR).
- FAA airport surveillance radar.
- Airborne radar.
What does NOAA stand for?
National Oceanic and Atmospheric Administration
What does FSS stand for?
Flight Service Station
What is the primary source for preflight weather information?
The Flight Service Station (FSS)
A preflight weather briefing from an FSS can be obtained 24 hours a day by calling
1-800-WX BRIEF
Telephone numbers for FSS can be found in
- The Chart Supplement U.S. (formerly Airport/Facility Directory)
- In the United States Government section of the phone book.
What does TIBS stand for?
Telephone Information Briefing Service
What is TIBS?
Provided by FSS
Automated telephone recordings of meteorological and aeronautical information.
TIBS provides area and route briefings, airspace procedures, and special announcements.
It is designed to be a preliminary briefing tool and is not intended to replace a standard briefing from a FSS specialist.
What does HIWAS stand for?
Hazardous Inflight Weather Advisory Service
What is HIWAS?
Automated continuous broadcast of hazardous weather information over selected VOR navigational aids (NAVAIDs).
Includes advisories such as AIRMETS, SIGMETS, convective SIGMETS, and urgent PIREPs.
VORs that have HIWAS capability are depicted on aeronautical charts with an “H” in the upper right corner of the identification box.
What does TWEB stand for?
(Alaska only)
Transcribed Weather Broadcast
What is TWEB?
Continuous automated broadcast of meteorological and aeronautical data over selected low or medium frequency (L/MF) and very high frequency (VHF) omnidirectional range (VOR) NAVAID facilities.
FSS Weather Briefings
The three types of FSS weather briefings.
- Standard
- Abbreviated
- Outlook
FSS Weather Briefings
Standard Briefing
Provides the most complete information and a more complete weather picture. This type of briefing should be obtained prior to the departure of any flight and should be used during flight planning.
FSS Weather Briefings
A standard briefing provides the following information in sequential order if it is applicable to the route of flight.
- Adverse conditions
- VFR flight not recommended
- Synopsis
- Current conditions (If depature time less than 2 hours away)
- En route forecast
- Destination forecast
- Forecast winds and temperatures aloft (temperature upon request)
- NOTAMs (when requested)
- ATC delays
- Other information
FSS Weather Briefings
Abbreviated Briefing
Shortened version of the standard briefing. It should be requested when a departure has been delayed or when weather information is needed to update the previous briefing.
FSS Weather Briefings
Outlook Briefing
An outlook briefing should be requested when a planned departure is 6 hours or more away. It provides initial forecast information that is limited in scope due to the time frame of the planned flight.
Aviation Weather Reports
What does METAR stand for?
Meteorological Terminal Aviation Routine Weather Report
Aviation Weather Reports
What is a METAR?
An observation of current surface weather reported in a standard international format.
Aviation Weather Reports
When are METARs issued?
Issued hourly at 55 minutes past the hour or anytime special weather events occur.
A special METAR (SPECI) can be issued at any time between routine METAR reports.
Aviation Weather Reports
A typical METAR report contains the following information in sequential order:
- Type of report
- Station identifier
- Date and time of report
- Modifier
- Wind
- Visibility
- Weather
- Sky condition
- Temperature and dew point
- Altimeter setting
- Zulu time
- Remarks
Aviation Weather Reports
What is a SPECI?
A special report that can be given at any time to update the METAR for rapidly changing weather conditions, aircraft mishaps, or other critical information.
Aviation Weather Reports
METAR - Station identifier
Four-letter code as established by the International Civil Aviation Organization (ICAO).
Aviation Weather Reports
METAR - Date and time of report
- Six-digit group (161753Z).
- The first two digits are the date.
- The last four digits are the UTC of the METAR/SPECI. Zulu time.
Aviation Weather Reports
METAR - Modifier
Modifier—denotes that the METAR/SPECI came from an automated source or that the report was corrected. If the notation “AUTO” is listed in the METAR/SPECI, the report came from an automated source. It also lists “AO1” (for no precipitation discriminator) or “AO2” (with precipitation discriminator) in the “Remarks” section to indicate the type of precipitation sensors employed at the automated station.
When the modifier “COR” is used, it identifies a corrected report sent out to replace an earlier report that contained an error (for example: METAR KGGG 161753Z COR).
Aviation Weather Reports
METAR - Wind
Five digits (14021KT) if speed greater than 99 knots, wind is reported with six digits.
First three digits indicate the direction the true wind is blowing from in tens of degrees.
Variable, is reported as “VRB.”
The last two digits indicate the speed of the wind in knots, if wind is greater than 99 knots, indicated by three digits.
If gusting, “G” follows wind speed (G26KT).
After “G,” the peak gust is provided.
If the wind direction varies more than 60° and the wind speed is greater than six knots, a separate group of numbers, separated by a “V,” will indicate the extremes of the wind directions.
Aviation Weather Reports
METAR - Visibilty
Prevailing visibility (¾ SM) reported in statute miles as denoted by the letters “SM.”
It is reported in both miles and fractions of miles.
At times, runway visual range (RVR) is reported following the prevailing visibility.
RVR is the distance a pilot can see down the runway in a moving aircraft.
When RVR is reported, it is shown with an R, then the runway number followed by a slant, then the visual range in feet.
For example, when the RVR is reported as R17L/1400FT, it translates to a visual range of 1,400 feet on runway 17 left.
Aviation Weather Reports
METAR - Weather
Can be broken down into two different categories: qualifiers and weather phenomenon (+TSRA BR).
First, the qualifiers of intensity, proximity, and the descriptor of the weather are given.
The intensity may be light (–), moderate ( ), or heavy (+).
Proximity only depicts weather phenomena that are in the airport vicinity.
The notation “VC” indicates a specific weather phenomenon is in the vicinity of five to ten miles from the airport.
Descriptors are used to describe certain types of precipitation and obscurations.
Weather phenomena may be reported as being precipitation, obscurations, and other phenomena, such as squalls or funnel clouds.
Descriptions of weather phenomena as they begin or end and hailstone size are also listed in the “Remarks” sections of the report.
Aviation Weather Reports
METAR - Sky condition
Always reported in the sequence of amount, height, and type or indefinite ceiling/height (vertical visibility) (BKN008 OVC012CB, VV003).
The heights of the cloud bases are reported with a three-digit number in hundreds of feet AGL.
Clouds above 12,000 feet are not detected or reported by an automated station.
The types of clouds, specifically towering cumulus (TCU) or cumulonimbus (CB) clouds, are reported with their height.
Contractions are used to describe the amount of cloud coverage and obscuring phenomena.
The amount of sky coverage is reported in eighths of the sky from horizon to horizon.
Aviation Weather Reports
METAR - Temperature and dew point
The air temperature and dew point are always given in degrees Celsius (C) or (18/17). Temperatures below 0 °C are preceded by the letter “M” to indicate minus.
Aviation Weather Reports
METAR - Altimeter setting
Reported as inches of mercury (“Hg) in a four-digit number group (A2970).
It is always preceded by the letter “A.”
Rising or falling pressure may also be denoted in the “Remarks” sections as “PRESRR” or “PRESFR,” respectively.
Aviation Weather Reports
METAR - Zulu time
UTC
Aviation Weather Reports
METAR - Remarks
The remarks section always begins with the letters “RMK.”
Comments may or may not appear in this section of the METAR.
The information contained in this section may include wind data, variable visibility, beginning and ending times of particular phenomenon, pressure information, and various other
information deemed necessary.
An example of a remark regarding weather phenomenon that does not fit in any other category would be: OCNL LTGICCG.
This translates as occasional lightning in the clouds and from cloud to ground.
Automated stations also use the remarks section to indicate the equipment needs
maintenance.
Aviation Weather Reports
What does PIREP stand for?
Pilot Weather Report
Aviation Weather Reports
What is a PIREP?
Reports of actual in-flight conditions issued by pilots. The best indication of actual flight conditions.
Aviation Weather Reports
What do PIREPs contain?
Reports include location, time, altitude, sky cover, visibility, observed weather, cloud layers, temperature, wind, possible turbulence and potential icing.
Aviation Weather Reports
A PIREP is normally transmitted as an individual report but may be appended to
a…
Surface report.
Aviation Weather Reports
Item numbers “blank” through “blank” are required information when making a report, as well as at least one…
- 1
- 5
- weather phenomenon encountered
Aviation Weather Reports
What are the two types of PIREPs?
- UA - Routine report.
- UUA - Urgent report.
Aviation Forecasts
What does TAF stand for?
Terminal Aerodrome Forecast
Aviation Forecasts
What is a TAF?
Reports forecasted winds, visibility, weather, sky conditions, and temperature.
Aviation Forecasts
When are TAF reports issued?
Scheduled 24 and 30 hour TAFs are issued four times per day, at 0000, 0600, 1200, and 1800Z
Aviation Forecasts
How long is a TAF report valid?
Each TAF is valid for a 24 or 30-hour time period
Aviation Forecasts
TAF reports are usually given for what kind of airports?
Larger airports.
Aviation Forecasts
The TAF utilizes the same descriptors and abbreviations as used in the…
METAR report.
Aviation Forecasts
What area is a TAF report for?
Five statute mile radius around an airport.
Aviation Forecasts
The TAF includes the following information in sequential order:
- Type of report
- ICAO station identifier
- Date and time of origin
- Valid period dates and times
- Forecast wind
- Forecast visibility
- Forecast significant weather
- Forecast sky condition
- Forecast change group
- PROB30
Aviation Forecasts
TAF - Type of report
A TAF can be either a routine forecast (TAF) or an amended forecast (TAF AMD).
Aviation Forecasts
TAF - ICAO station identifier
KPIR
The station identifier is the same as that used in a METAR.
Aviation Forecasts
TAF - Date and time of origin
081125Z
Time and date of TAF origination is given in the six-number code
* First two being the date
* The last four being the Zulu time.
Aviation Forecasts
TAF - Valid period dates and times
0812/0912
* Follows the date/time of forecast origin group.
* The first two digits (08) are the day of the month for the start of the TAF.
* The next two digits (12) are the starting hour (UTC).
* (09) is the day of the month for the end of the TAF
* The last two digits (12) are the ending hour (UTC) of the valid period.
* A forecast period that begins at midnight UTC is annotated as 00. If the end time of a valid period is at midnight UTC, it is annotated as 24.
* For example, a 00Z TAF issued on the 9th of the month and valid for 24 hours would have a valid period of 0900/0924.
Aviation Forecasts
TAF - Forecast wind
15011KT
* Five-digit number group.
* First three digits indicate the direction of the wind in reference to true north.
* The last two digits state the windspeed in knots appended with “KT.”
* Like the METAR, winds greater than 99 knots are given in three digits.
Aviation Forecasts
TAF - Forecast visibility
6SM
* Given in statute miles and may be in whole numbers or fractions.
* If the forecast is greater than six miles, it is coded as “P6SM.”
Aviation Forecasts
TAF - Forecast significant weather
Weather phenomena are coded in the TAF reports in the same format as the METAR.
Aviation Forecasts
TAF - Forecast sky condition
- Given in the same format as the METAR.
- Only cumulonimbus (CB) clouds are forecast in this portion of the TAF report as opposed to CBs and towering cumulus in the METAR.
Aviation Forecasts
TAF - Forecast change group
- For any significant weather change forecast to occur during the TAF time period, the expected conditions and time period are included in this group.
- This information may be shown as from (FM), and temporary (TEMPO).
- “FM” is used when a rapid and significant change, usually within an hour, is expected.
- “TEMPO” is used for temporary fluctuations of weather, expected to last less than 1 hour.
Aviation Forecasts
TAF - PROB30
- A given percentage that describes the probability of thunderstorms and precipitation occurring in the coming hours.
- This forecast is not used for the first 6 hours of the 24-hour forecast.
Aviation Forecasts
What does FA stand for?
Area Forecasts
Aviation Forecasts
What is an FA?
- Area Forecasts (FA) gives a picture of clouds, general weather conditions, and visual meteorological conditions (VMC) expected over a large area encompassing several states.
- This type of forecast gives information vital to en route operations, as well as forecast information for smaller airports that do not have terminal forecasts.
Aviation Forecasts
How many areas in the contiguous 48 states are FAs published?
6
Aviation Forecasts
How many times per day are FA issued?
3
Aviation Forecasts
How long are FAs valid for?
18 hours
Aviation Forecasts
How many sections are FAs typically disseminated in?
4 sections
Aviation Forecasts
FA - Header
- Location identifier of the source of the FA
- Date and time of issuance
- Valid forecast time
- Area of coverage
Example:
DFWC FA 120945
SYNOPSIS AND VFR CLDS/WX
SYNOPSIS VALID UNTIL 130400
CLDS/WX VALID UNTIL 122200…OTLK VALID
122200-130400
OK TX AR LA MS AL AND CSTL WTRS
Explanation:
The area forecast shows information given by Dallas Fort Worth, for the region of Oklahoma, Texas, Arkansas, Louisiana, Mississippi, and Alabama, as well as a portion of the Gulf coastal waters. It was issued on the 12th day of the month at 0945. The synopsis is valid from the time of issuance until 0400 hours on the 13th. VFR clouds and weather information on this area forecast are valid until 2200 hours on the 12th and the outlook is valid from 2200Z on the 12th to 0400Z on the 13th.
Aviation Forecasts
FA - Precautionary statements
- IFR conditions, mountain obscurations, and thunderstorm hazards are described in this section.
- Statements made here regarding height are given in MSL, and if given otherwise, AGL or ceiling (CIG) is noted.
Example:
SEE AIRMET SIERRA FOR IFR CONDS AND MTN OBSCN.
TS IMPLY SEV OR GTR TURB SEV ICE LLWS AND IFR CONDS.
NON MSL HGTS DENOTED BYAGL OR CIG.
Explanation:
The area forecast covers VFR clouds and weather, so the precautionary statement warns that AIRMET Sierra should be referenced for IFR conditions and mountain obscuration. The code TS indicates the possibility of thunderstorms and implies there may be occurrences of severe or greater turbulence, severe icing, low-level wind shear, and IFR conditions. The final line of the precautionary statement alerts the user that heights, for the most part, are MSL. Those that are not MSL will state AGL or CIG.
Aviation Forecasts
FA - Synopsis
Brief summary identifying the location and movement of pressure systems, fronts, and circulation patterns.
Example:
SYNOPSIS…LOW PRES TROF 10Z OK/TX PNHDL AREA FCST MOV EWD INTO CNTRL-SWRN OK BY 04Z. WRMFNT 10Z CNTRL OK-SRN AR-NRN MS FCST LIFT NWD INTO NERN OK-NRN AR EXTRM NRN MS BY 04Z.
Explanation:
As of 1000Z, there is a low pressure trough over the Oklahoma and Texas panhandle area, which is forecast to move eastward into central to southwestern Oklahoma by 0400Z. A warm front located over central Oklahoma, southern Arkansas, and northern Mississippi at 1000Z is forecast to lift northwestward into northeastern Oklahoma, northern Arkansas, and extreme northern Mississippi by 0400Z.
Aviation Forecasts
FA - VFR Clouds and Weather
This section lists expected sky conditions, visibility, and weather for the next 12 hours and an outlook for the following 6 hours.
Example:
S CNTRL AND SERN TX
AGL SCT-BKN010. TOPS 030. VIS 3-5SM BR. 14-16Z BECMG AGL SCT030. 19Z AGL SCT050.
OTLK…VFR
OK
PNDLAND NW…AGL SCT030 SCT-BKN100.
TOPS FL200.
15Z AGL SCT040 SCT100. AFT 20Z SCT TSRA DVLPG..FEW POSS SEV. CB TOPS FL450.
OTLK…VFR
Explanation:
In south central and southeastern Texas, there is a scattered to broken layer of clouds from 1,000 feet AGL with tops at 3,000 feet, visibility is 3 to 5 SM in mist. Between 1400Z and 1600Z, the cloud bases are expected to increase to 3,000 feet AGL. After 1900Z, the cloud bases are expected to continue to increase to 5,000 feet AGL and the outlook is VFR.
In northwestern Oklahoma and panhandle, the clouds are scattered at 3,000 feet with another scattered to broken layer at 10,000 feet AGL, with the tops at 20,000 feet. At 1500 Z, the lowest cloud base is expected to increase to 4,000 feet AGL with a scattered layer at 10,000 feet AGL. After 2000Z, the forecast calls for scattered thunderstorms with rain developing and a few becoming severe; the CB clouds have tops at flight level (FL) 450 or 45,000 feet MSL.
It should be noted that when information is given in the area forecast, locations may be given by states, regions, or specific geological features such as mountain ranges.
Aviation Forecasts
What are Inflight Weather Advisories?
- Provided to en route aircraft, forecasts that detail potentially hazardous weather.
- Also available to pilots prior to departure for flight planning purposes.
- Issued in the form of either an AIRMET, SIGMET, or convective SIGMET.
Aviation Forecasts
What does AIRMET stand for?
Airmen’s Meteorological Information
Aviation Forecasts
What is an AIRMET?
Advisory of significant weather phenomena hazardous to light aircraft.
* Moderate icing
* Moderate turbulance
* Surface winds of 30+ knots
* Widespread areas of ceilings less than 1,000 feet and/or visibilities less than 3 SM
* Extensive mountain obscurement.
The information contained in an AIRMET is of operational interest to all aircraft, but the weather section concerns phenomena considered potentially hazardous to light aircraft and aircraft with limited operational capabilities.
Aviation Forecasts
How long is an AIRMET issued for?
Issued for every 6-hour period with updates as needed.
Aviation Forecasts
How are AIRMETs designated/identified?
Each AIRMET bulletin has a fixed alphanumeric designator, numbered sequentially for easy identification, beginning with the first issuance of the day.
Example:
BOSS WA 211945
AIRMET SIERRA UPDT 3 FOR IFR AND MTN OBSCN
VALID UNTIL 220200
AIRMET IFT…ME NH VT MA CT RI NY NJ AND CSTL
WTRS FROM CAR TO YSJ TO 150E ACK TO EWR TO
YOW TO CAR OCNL CIG BLW 010/VIS BLW 3SM
PCPN/BR. CONDS CONT BYD 02Z THRU 08Z
AIRMET MTN OBSCN…ME NH VT MA NY PA
FROM CAR TO MLT TO CON TO SLT TO SYR TO CAR
MTNS OCNLY OBSCD BY CLDS/PCPN/BR. CONDS CONT BYD 02Z THRU 08Z
Explanation:
AIRMET SIERRA was issued for the Boston area at 1945Z on the 21st day of the month. SIERRA contains information on IFR and/or mountain obscurations. This is the third updated issuance of this Boston AIRMET series as indicated by “SIERRA UPDT 3” and is valid until 0200Z on the 22nd. The affected states within the BOS area are: Maine, New Hampshire, Vermont, Massachusetts, New York, and Pennsylvania. Within an area bounded by: Caribou, ME; to Saint Johns, New Brunswick; to 150 nautical miles east of Nantucket, MA; to Newark, NJ; to Ottawa, Ontario; to Caribou, ME. The effected states within Caribou, ME to Millinocket, ME to Concord, NH to Slate Run, PA to Syracuse, NY to Caribou, ME will experience ceilings below 1,000 feet/visibility below 3 SM, precipitation/mist. Conditions will continue beyond 0200Z through 0800Z.
Aviation Forecasts
What is an AIRMET Sierra?
IFR Conditions and mountain obscuration.
Aviation Forecasts
What is an AIRMET Tango?
Moderate turbulance, strong surface winds 30+ knots, and/or low-level wind shear.
Aviation Forecasts
What is an AIRMET Zulu?
Moderate icing and freezing levels.
Aviation Forecasts
What does SIGMET stand for?
Significant Meteorological Information
Aviation Forecasts
What is a SIGMET?
Inflight advisory of non-convective weather that is potentially hazardous to all aircraft.
They report weather forecasts that include severe icing not associated with thunderstorms, severe or extreme turbulence or clear air turbulence (CAT) not associated with thunderstorms, dust storms or sandstorms that lower surface or inflight visibilities to below three miles, and volcanic ash.
Aviation Forecasts
How long is a SIGMET valid for?
Valid for 4-hours
(6-hours if related to hurricane)
Aviation Forecasts
How are SIGMETs designated/identified?
- A SIGMET is issued under an alphabetic identifier, from November through Yankee.
- The first issuance of a SIGMET is designated as an Urgent Weather SIGMET (UWS).
- Reissued SIGMETs for the same weather phenomenon are sequentially numbered until the weather phenomenon ends.
Example:
SFOR WS 100130
SIGMET ROME02 VALID UNTIL 100530
OR WA
FROM SEA TO PDT TO EUG TO SEA
OCNL SEV CAT BTN FL280 AND FL350 EXPCD
DUE TO JTSTR.
CONDS BGNG AFT 0200Z CONTG BYD 0530Z .
Explanation:
This is SIGMET Romeo 2, the second issuance for this weather phenomenon. It is valid until the 10th day of the month at 0530Z time. This SIGMET is for Oregon and Washington, for a defined area from Seattle to Portland to Eugene to Seattle. It calls for occasional severe clear air turbulence between FL280 and FL350 due to the location of the jet stream. These conditions will begin after 0200Z and continue beyond the forecast scope of this SIGMET of 0530Z.
Aviation Forecasts
What is a CONVECTIVE SIGMET?
Inflight weather advisory issued for hazardous convective weather that affects the safety of all aircraft.
Aviation Forecasts
What does CONVECTIVE SIGMET stand for?
Convective Significant Meteorological Information
Aviation Forecasts
What is a CONVECTIVE SIGMET issued for?
Issued for:
* Severe thunderstorms with surface winds greater than 50 knots
* Hail at the surface greater than or equal to ¾ inch in diameter
* Tornadoes
Also issued to advise pilots of:
* Embedded thunderstorms
* Lines of thunderstorms
* Thunderstorms with heavy or greater precipitation that affect 40 percent or more of a 3,000 square mile or greater region.
Aviation Forecasts
Where are CONVECTIVE SIGMETs issued?
- Each area of the contiguous 48 states but not Alaska or Hawaii.
- Convective SIGMETs are issued for the eastern, western, and central USA.
Aviation Forecasts
When is a CONVECTIVE SIGMET issued and for how long?
- Issued at 55 minutes past the hour and valid for 2 hours.
- Special Convective SIGMETs can be issued during the interim for any reason.
Aviation Forecasts
How are CONVECTIVE SIGMETs designated/identified?
- They are numbered sequentially each day from 1–99, beginning at 00Z time.
- If no hazardous weather exists, the convective SIGMET is still issued; however, it states “CONVECTIVE SIGMET…NONE.”
Example:
MKCC WST 221855
CONVECTIVE SIGMET 20C
VALID UNTIL 2055Z
ND SD
FROM 90W MOT-GFK-ABR-90W MOT
INTSFYG AREA SEV TS MOVG FROM 24045KT. TOPS
ABV FL450. WIND GUSTS TO 60KTS RPRTD.
TORNADOES…HAIL TO 2 IN… WIND GUSTS TO 65KTS
POSS ND PTN
Explanation:
Convective SIGMET was issued for the central portion of the United States on the 22nd at 1855Z. This is the 20th Convective SIGMET issued on the 22nd for the central United States as indicated by “20C” and is valid until 2055Z. The affected states are North and South Dakota, from 90 nautical miles west of Minot, ND; to Grand Forks, ND; to Aberdeen, SD; to 90 nautical miles west of Minot, ND. An intensifying area of severe thunderstorms moving from 240 degrees at 45 knots (to the northeast). Thunderstorm tops will be above FL 450. Wind gusts up to 60 knots were reported. Also reported were tornadoes, hail to 2 inches in diameter, and
wind gusts to 65 knots possible in the North Dakota portion.
Aviation Forecasts
What does FB stand for?
Winds and Temperature Aloft Forecast
Aviation Forecasts
Where do FBs provide?
Provide wind and temperature forecasts for specific locations throughout the United States, including network locations in Hawaii and Alaska.
Aviation Forecasts
How often are FBs issued?
Twice a day based on the radiosonde upper air observations taken at 0000Z and 1200Z.
Aviation Forecasts
How are altitudes classfied in FBs?
Altitudes through 12,000 feet are classified as true altitudes, while altitudes 18,000 feet and above are classified as altitudes and are termed flight levels.
Aviation Forecasts
How is wind information given in an FB?
- Wind direction is always in reference to true north, and wind speed is given in knots.
- No winds are forecast when a given level is within 1,500 feet of the station elevation.
Aviation Forecasts
How is wind information formatted in an FB?
If the wind speed is forecast to be greater than 99 knots but less than 199 knots, the computer adds 50 to the direction and subtracts 100 from the speed. To decode this type of data group, the reverse must be accomplished. For example, when the data appears as “731960,” subtract 50 from the 73 and add 100 to the 19, and the wind would be 230° at 119 knots with a temperature of –60 °C. If the wind speed is forecast to be 200 knots or greater, the wind group is coded as 99 knots. For example, when the data appears as “7799,” subtract 50 from 77 and add 100 to 99, and the wind is 270° at 199 knots or greater. When the forecast wind speed is calm, or less than 5 knots, the data group is coded “9900,” which means light and variable.
Explanation of Figure 13-9: The heading indicates that this FB was transmitted on the 15th of the month at 1640Z and is based on the 1200Z upper air data. The valid time is 1800Z on the same day and should be used for the period between 1400Z and 2100Z. The heading also indicates that the temperatures above FL240 are negative. Therefore, the minus sign will be omitted for all forecast temperatures above FL240. A four-digit data group shows the wind direction in reference to true north and the wind speed in knots. The elevation at Amarillo, Texas (AMA) is 3,605 feet, so the lowest reportable altitude is 6,000 feet for the forecast winds. In this case, “2714” means the wind is forecast to be from 270° at a speed of 14 knots. A six-digit group includes the forecast temperature aloft. The elevation at Denver (DEN) is 5,431 feet, so the lowest reportable altitude is 9,000 feet for the winds and temperature forecast. In this case, “2321-04” indicates the wind is forecast to be from 230° at a speed of 21 knots with a temperature of –4 °C.
Aviation Forecasts
How is temperature information given in an FB?
- The temperature is given in degrees Celsius.
- Temperatures are not forecast for any station within 2,500 feet of the station elevation.
Weather Charts
What are weather charts?
Weather charts are graphic charts that depict current or forecast weather.
Weather Charts
Surface Analysis Chart
The surface analysis chart depicts an analysis of the current surface weather.
Weather Charts
How often are Surface Analysis Charts transmitted?
Every 3 hours.
Weather Charts
What do Surface Analysis Charts show?
- Areas of high and low pressure
- Fronts
- Temperatures
- Dew points
- Wind
- Directions and speeds
- Local weather
- Visual obstructions
Weather Charts
On Surface Analysis Charts what does the Station Model include?
- Sky cover
- Sea level pressure
- Pressure change/tendency
- Dew point
- Present weather
- Temperature
- Wind
Weather Charts
Surface Analysis Chart:
Sky Cover
The station model depicts total sky cover and is shown as clear, scattered, broken, overcast, or obscured/partially obscured.
Weather Charts
Surface Analysis Chart:
Sea level pressure
- Given in three digits to the nearest tenth of a millibar (mb).
- For 1,000 mbs or greater, prefix a 10 to the three digits.
- For less than 1,000 mbs, prefix a 9 to the three digits.
Weather Charts
Surface Analysis Chart:
Pressure change/tendency
- Pressure change in tenths of mb over the past 3 hours.
- This is depicted directly below the sea level pressure.
Weather Charts
Surface Analysis Chart:
Dew point
Given in degrees Fahrenheit.
Weather Charts
Surface Analysis Chart:
Present Weather
Over 100 different standard weather symbols are used to describe the current weather.
Weather Charts
Surface Analysis Chart:
Temperature
Given in degrees Fahrenheit.
Weather Charts
Surface Analysis Chart:
Wind
- True direction of wind is given by the wind pointer line, indicating the direction from which the wind is blowing.
- A short barb is equal to 5 knots of wind, a long barb is equal to 10 knots of wind, and a pennant is equal to 50 knots.
Weather Charts
What is the 34?
Surface Analysis Chart: Station Model
Temperature in Fahrenheit
Weather Charts
What is the 32?
Surface Analysis Chart: Station Model
Dew point in Fahrenheit
Weather Charts
What are the flag-like lines?
Surface Analysis Chart: Station Model
Wind speed and direction.
Weather Charts
What is the center dot?
Surface Analysis Chart: Station Model
Sky coverage amount.
Weather Charts
What is the **?
Surface Analysis Chart: Station Model
Present weather
Weather Charts
What is the 147?
Surface Analysis Chart: Station Model
Sea level pressure
1014.7 millibars (mb)
Note: Pressure is always shown in 3 digits to the nearest tenth of a millibar.
For 1,000 mb or greater, prefix a “10” to the 3 digits
For less than 1,000 mb, prefix a “9” to the 3 digits
Weather Charts
What is the 28?
Surface Analysis Chart: Station Model
Pressure change in the past 3 hours.
Increased steadily or unsteadily by 2.8 mb
Weather Charts
What is the /?
Surface Analysis Chart: Station Model
Pressure tendency
Weather Charts
What does a Weather Depiction Chart detail?
Surface conditions as derived from METAR and other surface observations.
Weather Charts
How often is a Weather Depiction Chart updated?
Prepared and transmitted by computer every 3 hours beginning at 0100Z time and is valid data for the forecast period.
Weather Charts
What is a Weather Depiction Chart used for?
Flight planning by giving an overall picture of the weather across the USA.
Weather Charts
How does the Weather Depiction Chart indicate flight rules?
- The weather depiction chart also provides a graphic display of IFR, VFR, and MVFR weather.
- IFR conditions are shown by a hatched area outlined by a smooth line.
- MVFR regions are shown by a nonhatched area outlined by a smooth line.
- VFR are not outlined.
- Also plotted are fronts, troughs, and squall lines from the previous hours surface analysis chart.
Weather Charts
How does the Weather Depiction Chart display the station model?
Weather depiction charts show a modified station model that provides sky conditions in the form of total sky cover, ceiling height, weather, and obstructions to visibility, but does not include winds or pressure readings like the surface analysis chart.
Weather Charts
On a Weather Depiction Chart, what does a bracket “]” symbol next to a station indicate?
The observation was made by an automated station.
Weather Charts: Significant Weather Prognostic Charts:
What is a the low-level Significant Weather chart?
Forecast of aviation weather hazards, primarily intended to be used as a guidance product for briefing the VFR pilot.
Weather Charts: Significant Weather Prognostic Charts:
What area does the low-level Significant Weather chart cover?
The forecast domain covers the 48 contiguous states, southern Canada and the coastal waters for altitudes below 24,000 ft.
Weather Charts: Significant Weather Prognostic Charts:
When are low-level Significant Weather charts issued?
- Low altitude Significant Weather charts are issued four times daily and are valid at fixed times: 0000, 0600, 1200, and 1800 UTC.
- Each chart is divided on the left and right into 12 and 24 hour forecast intervals (based on the current NAM model available).
ATC Radar Weather Displays
ATC refers to all weather areas displayed on ATC radar scopes as…
Precipitation
ATC Radar Weather Displays
All ATC facilities using radar weather processors with the ability to determine precipitation intensity, describe the intensity to pilots as:
- Light
- Moderate
- Heavy
- Extreme
ATC Radar Weather Displays
When the WARP is not available, a second system, the narrowband Air Route Surveillance Radar (ARSR) can display two distinct levels of precipitation intensity that is described to pilots as…
- “MODERATE”
- “HEAVY TO EXTREME”
ATC Radar Weather Displays
ATC facilities that cannot display the intensity levels of precipitation due to equipment limitations describe the location of the precipitation area by geographic position or position relative to the aircraft. Since the intensity level is not available, the controller states…
“INTENSITY UNKNOWN”
ATC Radar Weather Displays
ATC radar is not able to detect…
Turbulence.
ATC Radar Weather Displays: Weather Avoidance Assistance
To the extent possible, controllers will issue pertinent information on weather and assist pilots in avoiding such areas when requested. Pilots should respond to a weather advisory by either acknowledging the advisory or by acknowledging the advisory and requesting an alternative course of action as follows:
- Request to deviate off course by stating the number of miles and the direction of the requested deviation.
- Request a new route to avoid the affected area.
- Request a change of altitude.
- Request radar vectors around the affected areas.
ATC Radar Weather Displays: Weather Avoidance Assistance
The controller’s primary function is to…
Provide safe separation between aircraft.
Pilot Responsibility
Product latency
Be aware of the time stamp or “valid until” time on the particular data link information displayed in the flightdeck.
For example, since initial processing and transmission of NEXRAD data can take several minutes, pilots must assume that data link weather information will always be a minimum of seven to eight minutes older than shown on the time stamp and only use data link weather radar images for broad strategic avoidance of adverse weather.
Pilot Responsibility
Product update cycles
Be aware of when and how often a product is updated as well as the Data Link Service Providers (DLSP) update rate for particular products.
Pilot Responsibility
Indication of system failure
Be aware of partial or total system failure indications.
Pilot Responsibility
Coverage areas/service volume
- Coverage limitations are associated with the type of data link network being used.
- For example, ground-based systems that require a line-of-sight may have relatively limited coverage below 5,000 feet AGL.
- Satellite-based data link weather systems can have limitations stemming from whether the network is in geosynchronous orbit or low earth orbit.
- NWS NEXRAD coverage has gaps, especially in the western states.
Pilot Responsibility
Content/format
Since service providers often refine or enhance data link products for flightdeck display, pilots must be familiar with the content, format, and meaning of symbols and displays (i.e., the legend) in the specific system.
Pilot Responsibility
Data integrity/limitations to use
Reliability of information depicted. Be aware of any applicable disclaimer provided by the service provider.
Pilot Responsibility
Use of equipment/avionics display
- Pilots remain responsible for the proper use of an electronic flight bag (EFB) or installed avionics.
- Pilots should be cognizant that, per the FAA Practical Test Standards, they may be evaluated on the use and interpretation of an EFB or installed avionics on the aircraft.
Pilot Responsibility
Overload of Information
- Most DLSPs offer numerous products with information that can be layered on top of each other.
- Too much information can have a negative effect on cognitive work load.
- Manage the amount of information to a level that offers the most pertinent information to that specific flight without creating a distraction.
- Adjust the amount of information based on numerous factors including, but not limited to, the phase of flight, single pilot operation, autopilot availability, class of airspace, and the weather conditions encountered.
What does DLSP stand for?
Data Link Service Providers
What does ATIS stand for?
Automated Terminal Information Service
What is ATIS?
Recording of local weather conditions and other pertinent information broadcast on a local frequency in a looped format.
How often is ATIS updated?
Updated every hour by a human and given a unique identifier code.
