AIM Chapter 7 Meteorology Flashcards
Where can more details on weather products be found?
Advisory Circular 00-45, Aviation Weather Services
AIM 7-1-1
When will a SPECI be issued for a wind shift?
Wind direction changes by 45 degrees or more, in less than 15 minutes, and the wind speed is 10 knots or more throughout the wind shift
Table 7-1-1
When will a SPECI be issued for visibility?
When surface visibility decreases to less than or increases to equal to or exceeds:
3 SM
2 SM
1 SM
1/2 SM
1/4 SM or the lowest standard IAP minimums
Table 7-1-1
When will a SPECI be issued for RVR?
The highest value decreases to less than or increases to equal or exceed 2,400 ft during the preceeding 10 minutes
Table 7-1-1
When will a SPECI be issued for a Tornado, Funnel Cloud, or Waterspout?
When one is observed or disappears from sight or ends
Table 7-1-1
When will a SPECI be issued for a thunderstorm?
When one begins and is not already reported, or ends
Table 7-1-1
When will a SPECI be issued for precipitation?
Hill begins or ends
Freezing preciptation begins, ends, or changes intensity
Ice pellets begin, end, or change intensity
Snow begins, ends, or changes intensity
Table 7-1-1
When will a SPECI be issued for a squall?
When a squall occurs
(wind speed suddenly increases by at least 16 knots and is sustained at 22 knots or more for at least one minute)
Table 7-1-1
When will a SPECI be issued for the ceiling?
The ceiling decresases to less than or increases to equal or exceed:
3,000 ft
1,500 ft
1,000 ft
500 ft
200 ft or the lowest standard IAP minimums
Table 7-1-1
Will a SPECI be issued for a Volcanic Eruption?
Yes, when an eruption is first noted
Table 7-1-1
Will a SPECI be issued for an Aircraft Mishap?
Yes
Table 7-1-1
What is a Squall?
The wind speed suddenly increases by at least 16 knots and is sustained at 22 knots or more for at least one minute
Table 7-1-1
When can Graphical Forecasts for Aviation (GFA) data be viewed?
14 hours in the past to 15 hours in the future
AIM 7-1-4(a)
What does the Aviaiton Cloud Forecast provide?
Clouds coverage
Bases, layers, and tops
AIRMETS for mountain obsuctaion and icing
AIM 7-1-4(b)(4)
What does the Aviation Surface Forecast provide?
Visibility
Weather phenomena
Winds (including gusts)
AIRMETs for instrument flight rules and sustained surface winds of 30 knots or more
AIM 7-1-4(b)(4)
How often are the Aviaiton Surface Forecast and Aviaiton Cloud Forecast updated?
Every 3 hours
AIM 7-1-4(b)(4)
When should a Standard Briefing be requested?
Any time a previous briefing or preliminiary information through online resources has not been received
AIM 7-1-5(b)
When should an Abbreviated Breifing be requested?
Any time supplemental data is needed, to update a previous briefing, or when only a few specific items are needed
AIM 7-1-5(c)
When should an Outlook Briefing be requested?
When the propesed time of departure is 6 or more hours from the time of the briefing
AIM 7-1-5(d)
Who are SIGMETs intended for?
All pilots
AIM 7-1-6(d)(1)(a)
How long are SIGMETs valid for?
4 hours
6 hours for tropical cyclones and volcanic ash clouds
AIM 7-1-6(d)(1)(c)
How long are SIGMETs for tropical cyclones or volcanic ash clouds valid for?
6 hours
AIM 7-1-6(d)(1)(c)
When are SIGMETs issued?
As required
AIM 7-1-6(d)(1)(c)
What are SIGMETs issued for?
Severe icing not associated with thunderstorms
Severe or extreme turbulence not associated with thunderstorms
Clear air turbulence (CAT)
Widespread dust storms or sandstorms lowering surface visibility to below 3 miles
Volcanic Ash
AIM 7-1-6(d)(2)(d)
What are SIGMETs over Alaska and Hawaii/Oceanic Regions issued for?
Same as contiguous US
Tornadoes
Lines of thunderstorms
Embedded Thunderstorms
Hail greater than or equal to 3/4 inch in diameter
AIM 7-1-6(d)(3)(e)
AIM 7-1-6(d)(4)(d)
What is a severe thunderstorm?
Surface winds greater than or equal to 50 knots
Hail at the surface greater than or equal to 3/4 inches in diameter
Tornadoes
AIM 7-1-6(e)(1)(a)
What will a Convective SIGMET be issued for?
A severe thunderstorm
Embedded thunderstorms
A line of thunderstorms
Thunderstorms producing precipitation greater than or equal to heavy precipitation affecting 40% or more of an area at least 3,000 square miles
AIM 7-1-6(e)(1)
How often are Convective SIGMET bulletins issued?
Hourley at H+55
As required
AIM 7-1-6(e)(3)
Will a Convective SIGMET bulletin be issued if there is nothing meeting the required criteria?
Yes
The bulletin will state “CONVECTIVE SIGMET…NONE”
AIM 7-1-6(e)(3)
How long is a Convective SIGMET valid?
2 hours
AIM 7-1-6(e)(3)
What is an AIRMET?
A concise description of the occurrence or expected occurrence of specified en route weather phenomena that may affect the safety of aircraft operations, but at intensities lower than those which require the issuance of a SIGMET
AIM 7-1-6(f)
Who are AIRMETs intended for?
All pilots, but especially Visual Flight Rules pilots and operators of sensitive aircraft
AIM 7-1-6(f)(2)(a)
How long are AIRMETs valid for?
6 hours
8 hours in Alaska
AIM 7-1-6(f)(2)(b)
How often are AIRMETs issued?
Every 6 hours
Every 8 hours in Alaska
As necessary
AIM 7-1-6(f)(2)(b)
When are AIRMETs issued over the Contiguous US?
0245, 0845, 1445, 2045 UTC
Table 7-1-2
When are AIRMETs issued over Alaska?
Standard time
0515, 1315, 2115 UTC
Daylight savings time
0415, 1215, 2015 UTC
Table 7-1-2
When are AIRMETs issued over Hawaii?
0400, 1000, 1600, 2200 UTC
Table 7-1-2
What will an AIRMET Tango be issued for?
Moderate turbulence
Non-convective low-level wind shear potential below 2,000ft AGL
Sustained surface winds greater than 30 knotes
What will an AIRMET Zulu be issued for?
Moderate icing
Freezing levels
What will an AIRMET Sierra be issued for?
Widespread mountain obscuration
Instrument flight rule conditions
When are G-AIRMETs valid?
Discrete times no more than 3 hours apart for a period of up to 12 hours into the future
AIM 7-1-6(f)(3)
What is a Center Weather Advisory?
Unscheduled inflight, flow control, air traffic, and air crew advisory
(Not a flight planning product)
AIM 7-1-6(h)(1)
When will ARTCCs broadcast a Convective SIGMET, SIGMET, AIRMET, Urgent Pilot Report, or CWA?
Any part of the area described with within 150 miles of the airspace under their jurisdiction
AIM 7-1-8(a)
What does AWOS stand for?
Automated Weather Observing System
AIM 7-1-10(b)
What does ASOS stand for?
Automated Surface Observing System
AIM 7-1-10(d)
What does an AWOS-A report?
Altimeter setting only
Any other information is advisory only
AIM 7-1-10(b)(3)(a)
What does an AWOS-AV report?
Alimter
Visibility
Any other information is advisory only
AIM 7-1-10(b)(3)(b)
What does an AWOS-1 report?
Altimeter setting
Wind data
Temperature
Dew point
Density altitude
AIM 7-1-10(b)(3)(c)
What does an AWOS-2 report?
Altimeter setting
Wind data
Temperature
Dew point
Density altitude
Visibility
AIM 7-1-10(b)(3)(d)
What does an AWOS-3 report?
Altimeter setting
Wind data
Temperature
Dew point
Density altitude
Visibility
Cloud/ceiling data
AIM 7-1-10(b)(3)(e)
What does an AWOS-3P report?
Altimeter setting
Wind data
Temperature
Dew point
Density altitude
Visibility
Cloud/ceiling data
Precipitation identification
AIM 7-1-10(b)(3)(f)
What does an AWOS-3T report?
Altimeter setting
Wind data
Temperature
Dew point
Density altitude
Visibility
Cloud/ceiling data
Thunderstorm/lighting reporting
AIM 7-1-10(b)(3)(h)
What does an AWOS-3PT report?
Altimeter setting
Wind data
Temperature
Dew point
Density altitude
Visibility
Cloud/ceiling data
Precipitation identification
Thunderstorm/lighting reporting
AIM 7-1-10(b)(3)(g)
What does an AWOS-4 report?
Altimeter setting
Wind data
Temperature
Dew point
Density altitude
Visibility
Cloud/ceiling data
Precipitation occurrence, type, and accumulation
Freezing rain
Thunderstorm
Runway surface sensors
AIM 7-1-10(b)(3)(i)
What does an ASOS report?
Altimeter setting
Wind data
Temperature
Dew point
Density altitude
Visibility
Cloud/ceiling data
Precipitation identification, accumulation
Freezing rain
Remarks
When will an AWOS report weather and obstructions to visibility?
When the reported visibility is less than 7 miles
AIM 7-1-10(b)(2)
When will an AWOS report density altitude?
When the density altitude exceeds field elevation by more than 1,000ft
AIM 7-1-10(b)(2)
How does an AWOS calculate visibility?
Using a 10-minute harmonic average
AIM 7-1-10(b)(2)
Where is the AWOS visibility sensor located?
Near the touchdown of the primary instrument runway
AIM 7-1-10(b)(2)
How does an AWOS calculate sky condition/ceiling?
Integrates the last 30 minutes of ceilometer data
AIM 7-1-10(b)(2)
When will AUTO be added to a METAR?
When the data is derived from an automated system
AIM 7-1-10(b)(2)
What is the service volume of an AWOS?
A maximum of 25 NM and a maximum altitude of 10,000 feet AGL
AIM 7-1-10(b)(4)
How often does an AWOS update?
Every minute
AIM 7-1-10(b)(4)
How long is the typical AWOS message?
20-30 seconds
AIM 7-1-10(b)(4)
What does AO1 mean in the remarks?
Automated weather reporting stations without a precipitation discriminator
AIM 7-1-10(d)(5)
What does AO2 mean in the remarks?
Automated weather reporting stations with a precipitation discriminator
AIM 7-1-10(d)(5)
What automated remarks can be added to an AWOS broadcast?
Density Altitude
Variable Visibility
Variable Wind Direction
AIM 7-1-10(c)(5)(a)
What manual remarks can be added to an AWOS broadcast?
Type and intensity of precipitation
Thunderstorms and direction
Obstructions to vision when the visibility is 3 miles or less
AIM 7-1-10(c)(5)(b)
What does WARP stand for?
Weather and Radar Processor
AIM 7-1-12(a)(4)
How old can precipitation data be by the time it reaches an ARTCC controller’s display?
Up to 6 minutes old
AIM 7-1-12(a)(4)
What does ARSR stand for?
Air Route Surveillance Radar
AIM 7-1-12(a)(4)
Can ATC radar detect turbulence?
No
AIM 7-1-12(a)(5)
What should a pilot state when requesting a deviation for weather?
Heading or degrees
Direction of deviation
Approxiamte number of miles
AIM 7-1-12 (b)(1)(a)
When will ATC advise pilot of light precipitation?
<26 dBZ
AIM 7-1-12(a)(2)(a)
When will ATC advise pilots of moderate precipitation?
26 to 40 dBZ
AIM 7-1-12(a)(2)(b)
When will ATC advise pilots of heavy precipitation?
> 40 to 50 dBZ
AIM 7-1-12(a)(2)(c)
When will ATC advise pilots of extreme precipitation?
> 50 dBZ
AIM 7-1-12(a)(2)(d)
When wil RVR be reported?
When the prevailing visibility is less than one mile and/or the RVR is 6,000 feet or less
AIM 7-1-13(g)
What is the definition of ceiling?
The lowest layer of clouds or obscuring phenomenon that is reported “broken,” “overcast,” or “obscuration”
7-1-14(a)
What is the height of clouds reported in?
Height above ground level
In PIREPs, clouds are reported in MSL
7-1-14(a)
7-1-14(b)
What is prevailing visibility?
The greatest visibility equaled or exceeded throughout at least one half of the horizon circle, not necessarily contiguous
7-1-15(b)
When will tower visibility be reported?
When it is less than 4 miles
AIM 7-1-15(c)
How is light rain identified?
Scattered drops that, regardless of duration, do not completely wet an exposed surface up to a condition where individual drops are easily seen
AIM 7-1-16(a)(1)
How is moderate rain identified?
Individual drops are not clearly identifiable; spray is observable just above pavements and other hard surfaces
AIM 7-1-16(a)(2)
How is heavy rain identified?
Rain seemingly falls in sheets; individual drops are not identifiable; heavy spray to height of several inches is observed over hard surfaces
aIM 7-1-16(a)(3)
How are light ice pellets identified?
Scattered pellets that do not completely cover an exposed surface regarless of duration. Visibility is not affected
AIM 7-1-16(b)(1)
How are moderate ice pellets identified?
Slow accumulation on ground. Visibility reduced by ice pellets to less than 7 statute miles
AIM 7-1-16(b)(2)
How are heavy ice pellets identified?
Rapid accumulation on ground. Visibility reduced by ice pellets to less than 3 statute miles
AIM 7-1-16(b)(3)
How is light drizzle identified?
Visibility more than 1/2 statute mile
AIM 7-1-17(a)
How is moderate drizzle identified?
Visibility from more than 1/4 statute mile to 1/2 statute mile
AIM 7-1-17(b)
How is heavy drizzle identified?
Visibility 1/4 statute mile or less
AIM 7-1-17(c)
How is light snow identified?
Visibility more than 1/2 statute mile
AIM 7-1-17(a)
How is moderate snow identified?
Visibility from more than 1/4 statute mile to 1/2 statute mile
AIM 7-1-17(b)
How is heavy snow identified?
Visibility 1/4 statute mile or less
AIM 7-1-17(c)
When is ATC requried to solicit PIREPs?
Ceilings at or below 5,000 feet
Visibility at or below 5 miles (surface or aloft)
Thunderstorms and related phenomena
Light icing or greater
Moderate turbulence or greater
Wind shear
Volcanic ash clouds
AIM 7-1-18(a)
Who can pilots give PIREPs to?
FSS
ARTCC
Terminal ATC
AIM 7-1-18(c)
It takes ____ inch of ice to reduce the lifting power of some aircraft by ____ percent and increases the frictional drag by an equal percentage
1/2 inch
50%
AIM 7-1-19(a)
When can a pilot expect icing?
Visibile precipitation
Temperature is between +02 and -10 degrees Celsius
AIM 7-1-19(b)
What is trace icing?
Ice becomes noticeable
AIM 7-1-19(b)(1)
What is the accumulation rate of trace icing?
Less than 1/4 inch per hour on the outer wing
AIM 7-1-19(b)(1)
What is light icing?
The rate of ice accumulation requires occasional cycling of manual deicing systems to minimize ice accretions on the airframe
AIM 7-1-19(b)(2)
What is the accumulation rate of light icing?
1/4 inch to 1 inch per hour on the unprotected part of the outer wing
AIM 7-1-19(b)(2)
What is moderate icing?
The rate of ice accumulation requries frequent cycling of manual deicing systems to minimize ice accretions on the airframe
AIM 7-1-19(b)(3)
What is the accumulation rate of moderate icing?
1 to 3 inches per hour on the unprotected part of the outer wing
AIM 7-1-19(b)(3)
What is severe icing?
The rate of ice accumulation is such that ice protection systems fail to remove the accumulation of ice and ice accumulations in locations not normally prone to icing, such as areas aft of protected surfaces
Immediate exit is required
AIM 7-1-19(b)(4)
What is the accumulation rate of severe icing?
More than 3 inches per hour
Immediate exit is required
AIM 7-1-19(b)(4)
What is rime ice?
Rough, milky, opaque ice formed by the instantaneous freezing of small supercooled water droplets
Table 7-1-9
What is mixed ice?
Simultaneous apprearance or a combination of rime and glaze ice
Table 7-1-9
What is clear ice?
A glossy, clear, or translucent ice formed by the relatively slow freezing of large supercooled water droplets
Table 7-1-9
What is intercycle ice?
Ice which accumulates on a protected surface between actuation cycles of a deicing system
Table 7-1-9
What is residual ice?
Ice which remains on a protected surface immediately after the actuation of a deicing system
Table 7-1-9
What is runback ice?
Ice which forms from the freezing or refreezing of water leaving protected surfaces and running back to unprotected surfaces
Table 7-1-9
What is the aircraft reaction to light turbulence?
Momentarily causes slight, erratic changes in altitude and/or attitude
Table 7-1-11
What is the aircraft reaction to light chop?
Slight, rapid, and somewhat rhythmic bumpiness without appreciable changes in altitude or attitude
Table 7-1-11
What is the reaction inside the aircraft to light turbulence or light chop?
Occupants may feel a slight strain against seat belts or shoulders straps
Unsecured objects may be displaced slightly
Table 7-1-11
What is the aircraft reaction to moderate turbulence?
Similar to light turbulence but of greater intensity
Changes in altitude and/or attitude occur but the aircraft remains in positive control at all times. It usually causes variations in indicated airspeed
Table 7-1-11
What is the aircraft reaction to moderate chop?
Similar to light chop but of greater intensity.
Rapid bumps or jolts without appreciable changes in aircraft altitude or attitude
Table 7-1-11
What is the reaction inside the aircraft to moderate turbulence or moderate chop?
Occupants feel definite strains against seat belts or sholder straps
Unsecured objects are dislodged
Table 7-1-11
What is the aircraft reaction to severe turbulence?
Large, abrupt changes in altitude and/or attitude. It usually causes large variations in indicated airspeed
Aircraft may be momentarily out of control
Table 7-1-11
What is the reaction inside the aircraft?
Occupants are forced violently against seat belts or shoulder straps
Unsecured objects are tossed about
Table 7-1-11
What is the aircraft reaction to extreme turbulence?
The aircraft is violently tossed about an is practically impossible to control
May cuase structural damage
Table 7-1-11
What is occasional turbulence?
Less than 1/3 of the time
Table 7-1-11
What is intermittent turbulence?
1/3 to 2/3 of the time
Table 7-1-11
What is continuous turbulence?
More than 2/3 of the time
Table 7-1-11
How should a pilot report windshear to ATC?
State the loss or gain of airspeed and the altitudes at which it was encountered
AIM 7-1-22(b)
Clear Air Turbulence is an escepcially serious operational factor to flight operations above what altitude?
15,000ft
AIM 7-1-23
What is a microburst?
Small scale intense downdrafts which, on reaching the surface, spread outward in all directions
AIM 7-1-24(a)
How long does a microburst intensidy for after reaching the ground?
5 minutes
AIM 7-1-24(c)
How wide is a microburst?
1 mile in diameter
AIM 7-1-24(d)(1)
How wide is the transition zone of a microburst downdraft near the ground?
2 1/2 miles
AIM 7-1-24(d)(1)
How strong can the downdrafts be in a microburst?
6000 fpm
AIM 7-1-24(d)(2)
How strong can horizontal winds near a microburst at the surface be?
45 knots
AIM 7-1-24(d)(2)
How long can a microburst last?
15 minutes
AIM 7-1-24(d)(4)
How long will the maximum intensity winds last in a microburst?
2-4 minutes
AIM 7-1-24(d)(4)
Where do microbursts commonly occur?
Within the heavy rain portion of thunderstorms and in much weaker benign appearing convective cells that have little or no precipitation reaching the ground
AIM 7-1-24(d)(3)
What does LLWAS stand for?
Low Level Wind Shear Alert System
AIM 7-1-24(f)(2)
What is the most abundant gas found in volcanic eruptions?
Sulpher dioxide (SO2)
AIM 7-1-25(a)
What does sulphur dioxide smell like?
Rotten eggs
AIM 7-1-25(a)
How far can severe turbulence be expected from a severe thunderstorm?
Up to 20 miles
AIM 7-1-26(b)
How far can severe turbulence be expected from less severe thunderstorms?
10 miles
AIM 7-1-26(b)
Is flight between two radar echoes recommended?
No!
AIM 7-1-26(c)
No flight path through an area of strong or very strong radar echoes separated by ___ to ___ miles or less may be considered free of severe turbulence
20 to 30 miles
AIM 7-1-26(c)
At what temperatures does the probability of lighting strikes the greatest?
-5 degrees to +5 degrees Celsius
AIM 7-1-26(e)
Should you fly under the anvil of a thunderstorm?
No!
AIM 7-1-27(a)(3)
Can NEXRAD be used for tacticle thunderstorm avoidance?
No
Weather conditions displayed may be 15 to 20 minutes older and current conditions
AIM 7-1-26(a)(8)
How far should you avoid a thunderstorm?
20 miles
AIM 7-1-27(a)(14)
What should you try to maintain if you fly into a thunderstorm?
A constant attitude
AIM 7-1-27(c)(2)
Should you try to turn around if you enter a thunderstorm?
No
Fly a straight course through the storm
AIM 7-1-27(c)(4)
What is a METAR?
Aviation Routine Weather Report
AIM 7-1-29 (b)(1)(a)
What is a SPECI?
Nonroutine (Special) Aviation Weather Report
AIM. 7-1-29 (b)(1)(b)
What does COR mean in a METAR?
The report was corrected
AIM 7-1-29 (b)(4)
How will the wind be coded in a METAR if the wind speed is over 99 knots?
Six digits
First three will be degrees, next three will be wind speed
AIM 7-1-29(b)(5)
When will “V” be coded in the METAR wind group?
If the wind direction is variable by 60 degrees or more and the speed is greater than 6 knots
AIM 7-1-29
When will “VRB” be in the METAR wind group?
If the wind direction is variable by 60 degrees or more and the speed is equal to or less than 6 knots
AIM 7-1-29
Are winds reported as magnetic or true?
TRUE
If written they’re true, when spoken they’re magnetic
AIM 7-1-29(b)(5)
When will peak wind be reported?
When the peak wind exceeds 25 knots
AIM 7-1-29(b)(5)(a)
Can an AWOS show visibility less than 1/4 SM?
No
Coded as M1/2SM
AIM 7-1-29(b)(6)(b)
When will variable visibility be reported?
When there is a rapid increase or decrease by 1/2 SM or more and the average prevailing visibility is less than 3SM
AIM 7-1-29(b)(6)(c)
When will sector visibility be reported?
Coded in the remarks when it differs from the prevailing visibility and either the prevailing or sector visibility is less than 3SM
AIM 7-1-29(b)(6)(d)
What is the distance of VC (vicinity)?
Between 5 and 10 miles
AIM 7-1-29(b)(12)
What is the distance of DSNT (distant)?
Beyond 10 but less than 30 miles
AIM 7-1-29(b)(12)
What does “TS” mean?
METAR/TAF
Thunderstorm
AIM 7-1-29(b)(8)(c)
Descriptor
What does “DR” mean?
METAR/TAF
Low drifting
AIM 7-1-29(b)(8)(c)
Descriptor
What does “SH” mean?
METAR/TAF
Showers
AIM 7-1-29(b)(8)(c)
Descriptor
What does “MI” mean?
METAR/TAF
Shallow
AIM 7-1-29(b)(8)(c)
Descriptor
What does “FZ” mean?
METAR/TAF
Freezing
AIM 7-1-29(b)(8)(c)
Descriptor
What does “BC” mean?
METAR/TAF
Patches
AIM 7-1-29(b)(8)(c)
Descriptor
What does “BL” mean?
METAR/TAF
Blowing
AIM 7-1-29(b)(8)(c)
Descriptor
What does “PR” mean?
METAR/TAF
Partial
AIM 7-1-29(b)(8)(c)
Descriptor
What is “+TSRA” mean in a METAR?
Thunderstorm with heavy rain
What does “RA” mean?
METAR/TAF
Rain
AIM 7-1-29(b)(8)(d)
Precipitation
What does “DZ” mean?
METAR/TAF
Drizzle
AIM 7-1-29(b)(8)(d)
Precipitation
What does “GR” mean?
METAR/TAF
Hail
(diameter of 1/4” or greater)
AIM 7-1-29(b)(8)(d)
Precipitation
What does “GS” mean?
METAR/TAF
Small hail
Snow pellets
AIM 7-1-29(b)(8)(d)
Precipitation
What does “PL” mean?
METAR/TAF
Ice pellets
AIM 7-1-29(b)(8)(d)
Precipitation
What does “SG” mean?
METAR/TAF
Snow grains
AIM 7-1-29(b)(8)(d)
Precipitation
What does “IC” mean?
METAR/TAF
Ice Crystals
(diamond dust)
AIM 7-1-29(b)(8)(d)
Precipitation
What does “UP” mean?
METAR
Unknown Precipitation
(automated stations only)
AIM 7-1-29(b)(8)(d)
Precipitation
What does “FG” mean?
METAR/TAF
Fog
(visibility less than 5/8 mile)
AIM 7-1-29(b)(8)(e)
Obstruction to Visibility
What does “HZ” mean?
METAR/TAF
Haze
AIM 7-1-29(b)(8)(e)
Obstruction to Visibility
What does “FU” mean?
METAR/TAF
Smoke
AIM 7-1-29(b)(8)(e)
Obstruction to Visibility
What does “PY” mean?
METAR/TAF
Spray
AIM 7-1-29(b)(8)(e)
Obstruction to Visibility
What does “BR” mean?
METAR/TAF
Mist
(visibility 5/8 - 6 miles)
AIM 7-1-29(b)(8)(e)
Obstruction to Visibility
What does “SA” mean?
METAR/TAF
Sand
AIM 7-1-29(b)(8)(e)
Obstruction to Visibility
What does “DU” mean?
METAR/TAF
Dust
AIM 7-1-29(b)(8)(e)
Obstruction to Visibility
What does “VA” mean?
METAR/TAF
Volcanic Ash
AIM 7-1-29(b)(8)(e)
Obstruction to Visibility
What does “SQ” mean?
METAR/TAF
Squall
AIM 7-1-29(b)(8)(f)
Other
What does “SS” mean?
METAR/TAF
Sandstorm
AIM 7-1-29(b)(8)(f)
Other
What does “DS” mean?
METAR/TAF
Duststorm
AIM 7-1-29(b)(8)(f)
Other
What does “PO” mean?
METAR/TAF
Dust/sand whirls
AIM 7-1-29(b)(8)(f)
Other
What does “FC” mean?
METAR/TAF
Funnel Cloud
AIM 7-1-29(b)(8)(f)
Other
What does “+FC” mean?
METAR/TAF
Tornado/Waterspout
AIM 7-1-29(b)(8)(f)
Other
How much of the sky does FEW obscure?
> 0 to 2/8
AIM 7-1-29(b)(9)(a)
How much of the sky does SCT obscure?
3/4 to 4/8
AIM 7-1-29(b)(9)(a)
How much of the sky does BKN obscure?
5/8 to 7/8
AIM 7-1-29(b)(9)(a)
How much of the sky does OVC obscure?
8/8
AIM 7-1-29(b)(9)(a)
What does “CB” mean?
METAR/TAF
Cumulonimbus
(when present)
AIM 7-1-29(b)(9)(a)
Sky Condition
What does “TCU” mean?
METAR
Towering cumulus
(when present)
AIM 7-1-29(b)(9)(a)
Sky Condition
When will “SKC” be reported?
METAR
Sky clear at manual stations
AIM 7-1-29(b)(9) Note 1
When will “CLR” be reported?
No clouds below 12,000ft at automated stations
AIM 7-1-29(b)(9) Note 1
When will variable ceiling be reported?
When the ceiling is below 3,000 feet and is variable
AIM 7-1-10(b)(9)(g)
What does “CBMAM” mean?
METAR
Cumulonimbus Mammatus
AIM 7-1-29(b)(9)(j)(1)
What does “ACC” mean?
METAR
Altocumuls Castellanus
AIM 7-1-29(b)(9)(j)(3)
What does “SCSL” mean?
METAR
Stratocumulus Standing Lenticular
AIM 7-1-29(b)(9)(j)(3)
What does “ACSL” mean?
METAR
Altocumulus Standing Lenticular
AIM 7-1-29(b)(9)(j)(3)
What does “CCSL” mean?
METAR
Cirrocumulus Standing Lenticular
AIM 7-1-29(b)(9)(j)(3)
What unit of distance is lighting reported in?
Nautical Miles
What does TAF stand for?
Aerodrome Forecast
AIM 7-1-29(c)
How long is a TAF valid?
24 hours
30 hours at select airports
AIM 7-1-29(c)
When will calm wind be reported in a METAR or TAF?
3 knots or less
AIM 7-1-29
What is the highest visibility forecasted in a TAF?
6SM
(P6SM)
AIM 7-1-29(c)(5)(b)
Will “CLR” ever be reported in a TAF?
No, only SKC will be used
AIM 7-1-29(c)(5)(d)
What does the PROB group mean?
TAF
The probability or chance of thunderstorms or other precipitation events occurin, along with associated weather conditions
AIM 7-1-29(c)(5)d)
What does PROB30 mean?
TAF
The probability of the occurrence of thunderstorms or precipitation is 30-39%
AIM 7-1-29(c)(5)d)
What does the FM group mean?
TAF
Used when a rapid change, usually occuring in less than one hour, in previaling conditions is expected
AIM 7-1-29(c)(5)(e)(1)
What does the BECMG group mean?
TAF
Used when a gradual change in conditions is expected over a longer time period, usually 2 hours
NWS does not use the BECMG group
AIM 7-1-29(c)(5)(e)(2)
What does the TEMPO group?
TAF
Used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time, and are expected to occur during less than half the time period
AIM 7-1-29(c)(5)(e)(3)
Under what part are aircraft certified for flight in icing conditions?
14 CFR Part 25 or Part 29 Appendix C
What is drizzle?
Precipitation at the ground or aloft that in form of liquid water drops with diameters less than 0.5mm an greater than 0.05mm
What is rain?
Water droplets greater than 0.5mm in diameter
How big are cloud droplets?
Less than 0.05mm in diameter
Prrrr
P group
METAR Remarks
Hourly Precipitation Amount
P0000
METAR Remark
Trace Precipitation
6RRRR
6 group
METAR Remarks
3- and 6- hourly preciptation
60000
METAR Remarks
Trace Precipitation
7RRRR
7 group
METAR Remarks
24-hour precipitation
In the 1200 UTC report
4/sss
4/ group
METAR Remarks
Snow Depth on Ground
933RRR
933 group
METAR Remarks
Water Equivalent of Snow on Ground
98mmm
98 group
METAR Remarks
Duration of Sunshine
TsTTTsTTT
T group
METAR Remarks
Hourly Temperature and Dew Point
1sTTT
1 group
METAR Remarks
6-Hourly Maximum Temperature
2sTTT
2 group
METAR Remarks
6-Hourly Minimum Temperature
4sTTTsTTT
4 group
METAR Remarks
24-hour Maximum and Minimum Temperature
5appp
5 group
METAR Remarks
3-Hourly Pressure Tendency
What does “RVRNO” mean?
METAR Remarks
Runway Visual Range is missing
What does “PWINO” mean?
METAR Remarks
Present weather identifier is not operating
What does “PNO” mean?
METAR Remarks
Tipping bucket rain gauge is not operating
What does “FZRANO” mean?
METAR Remarks
Freezing rain sensor is not operating
What does “TSNO” mean?
METAR Remarks
Lightning detection system is not operating
What does “VISNO_LOC” mean?
METAR Remarks
Secondary visibility sensor is not operating
What does “CHINO_LOC” mean?
METAR Remarks
Secondary ceiling height indicator is not operating
What does “$” mean?
METAR Remarks
Maintenance is needed on the system
