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Flashcards in Weather Deck (14)
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What is a METAR?

Aviation routine weather report (French orig)
Used for current WX where TAF is future
Observers interpretation or fully "auto" A01 A02
Must be done no earlier than 15 min prior time
Date, time, group format
Typically 55-59 past hr but have seen 53 (KVGT)
Groups include:
Winds in true
RVR if available
WX phenomena
Sky condition (ceilings)
Temp/dew point

Remarks will indicate A01 or A02. A01 can determine precipitation where A02 can determine the type of precipitation I.e. Rain, sleet, snow.

Also, you will notice (SLP 236) and (T01231032). This is Sea level Pressure and temp/dew point to the tenths.

Add 10 to 236 to get SLP in hectopascals so it would be 1023.6

Break down the temp and dew point into two groups of 4. The first # will always be a 0 or 1. 0 =positive and 1=negative. For the example above temp is positive 12.3 and dew point is negative 3.2.


What is a TAF?

Terminal Aerodrome forecast
Same Day, Time, Group as METAR
Expected WX within 5 sm from aerodrome
4 x day (0000, 0600, 1200, 1800)
Forecast is for 24 hrs (1118/1218) day/time
32 large aerodrome use ICAO 30 hr format


What is a Area Forecast?

Forecast of VMC conditions in area:
Sfo, Slc, chi, dfw, Mia, bos, ak, hi, carr

Issued 3x day
Product header
Precautionary statement (airmet S)
Synopsis=big picture 18 hr
Forecast=12 hr VMC WX forecast
Outlook=6 hr outlook (vfr or IFR )
Total 18 hrs


Surface analysis chart?

Computer generated from past observation
Comes out every 3 hrs
Valid time on chart is typically 2-3 hrs old
pressure systems highs and lows
Pressure gradients with isobars (4 mb or hPa spacing) 1013 mb=1013 hPa
Frontal positions: cold, warm, stationary, occluded
Ridges and troughs
Squall lines

The first of a four panel surface analysis prognosis


Radar summary chart?

Supposedly comes out 35 past hr
Composite display of many radar sites
Shows echo intensities and tops
Also shows cell movement with wind barb
Displays precip only not clouds
Used in conjunction with other reports


Winds and temps aloft chart?

Forecasted from stations all over the US
Displayed as text or graphics
FB(freezing breeze)=2 x day, 0000z and 1200z
Valid times are stated on chart
11 common altitudes
Aids pilot:
Determine most favorable alt for winds
Icing levels +2 to -20
Predicting turb with abrupt wind change
Text is 6 digit 2607+15
Above FL240 assumed temp is neg 2703020
No wind data within 1500 of station (METAR)
9900 =light and variable
If winds greater than 100
-50 from direction and +100 to speed
731960=winds 230 @ 119 kts -60c


Significant WX prognostic chart?

2 days divided into 4 12 hr time periods
0 hr (surface analysis)
Prognosis 12 hr, 24, 36 and 48 hr
Displays forecasted:
SIGMET and airmet type WX
Freezing locations
TS, hail, rain,snow with symbology (cave markings)
Expected IFR conditions
Frontal locations
Pressure systems


Convective outlook chart?

Picture a map with lines that delineate areas of thunderstorms and convective activity by using the qualifiers: slgt, mod, high

Issued when needed



All part of terminal broadcast system
ATIS=continuously broadcasted terminal information meant to reduce atc workload

Coded in phonetic letters, typically updated 53 past the hour or when sig change has occurred such as runway direction due to winds

Time, ceiling, Vis, sky phen, temp/dew, wind, alt, remarks such as rwy in use. Sometimes if the above ceiling, sky cond isn't a factor it will be omitted

Automates surface or weather observation systems:
Up to the minute updates from WX equip on airport

If human observer present, info will be used for ATIS and METAR


Types of Thunder storms

Air Mass=short lived like monsoon caused by quick intro of moisture or temp difference

Steady State= assoc with storm fronts and continue to feed off each other



WX deemed to have sig impact on all types of A/C. Expected to occur in a area of at least 3000 sq miles or an area with sig impact

Convective SIGMET:
Issued as req at 55 past hr
Valid up to 2 hrs
Line of TS
Surface winds >= 50 kts due to conv
Hail at surface >= 3/4 " diameter

SIGMET (non convective and weird stuff)
Severe icing
Severe to extreme turb
Dust storms/sand storms that reduce Vis lower than 3sm
Volcanic ash
Hurricane ( forecasted for 6 hrs)

AIRMET (think moderate not severe)
issued as needed and good for 6 hrs
Mod Icing (Z)
Mod turb (T)
Ceilings less than 1000 and Vis less than 3 as well as mountain obscuration (S)
Sustained Surface winds >=30 kts




Required when encountering WX not forecasted, wind shear, or if you go missed due to WX

UA/OV OKC 063064/TM1522/FL080/TP C172/type of WX encountered


Windshear Reports

Sensors placed in different loc of aerodrome that can detect differences in wind

Terminal dopplar detects wind shear

Integrated Terminal WX System (ITWS)Multiple systems deliver warnings of ARENA to ATC via WX system processor


Icing and freezing level information

Icing decreases lift and increases drag

FB winds temps aloft
Sig WX charts