Chapter 10: Aviation weather reports and forecast

Constant pressure analysis chart

Data collected across the country take pressure samples and create a pressure analysis chart. Issue twice a day at 0000 Zulu in 1200 Zulu

METAR. Aviation routine weather report

Observation of current weather conditions within a 5 to 10 mile radius of a specific station. Issued hourly at 55 past the hour. Same information as ATIS. Shows station identifier, date, time, modifiers, wind, visibility, weather, sky condition, temperature, dewpoint, altimeter settings and air marks as needed.

Prognostic chart

Surface mid-level and High level charts. Current observations, 12, 24, 36 and 48 hour forecast. Shows pressure systems, fronts and weather conditions. Issued four times a day.

TWEB. Transmitted weather broadcast

Weather transmitted continuously over certain VOR's only in Alaska

Upper air observation

Aircraft include carry radio sones to record conditions at a higher altitudes

ASOS Automated surface observation system

All info of AWOS plus variable cloud Heights, variable visibility, rapid pressure changes, precipitation type, intensity, accumulation, and beginning and ending times.

HIWAS. Hazardous in-flight weather advisory service

Broadcast over certain DORs. Contains information such as airmets and sigmets and convective sigmets and urgent pireps

TAF terminal airdrome forecast

Computer-generated estimate a future weather conditions. Typically 5 to 10 statute mile radius around reporting station. Valid for up to 24 hours. Can be 30. Updated every six hours. If forecast changes significantly and amended TAF will be issued.

Radar summary chart

Computer-generated summary of different precipitation echoes and they are intensities. Reported at 35 past the hour with sooner updates as necessary. All heights reported in msl

Convective sigmets

Convective activity only. Issued hourly at 55 past the hour. Valid for two hours or until superseded. Issued for severe icing and extreme turbulence. Low level windshear, tornadoes, squall lines, embedded thunderstorms 3/4 inch plus hail and wind gusts in excess of 50 knots at the surface

Area forecast

Covers general weather conditions over a region. Useful for cross-country flights. There are six area forecast in United States. Valid for 12 hours plus a six hour outlook. Issued three times a day

Low level significant weather prognostic chart

Forecasts rather than observations. Good overall view of the weather that is expected to occur. Four panel chart showing forecast from the surface up to 24,000 feet MSL at the valid time on chart. Two left panels are 12 hour forecast from the issuance. Two right panels are 24 hour forecast from the issuance. Upper panel showed significant weather prognosis. Lower panels show surface prognosis

Hurricane advisor

Issues when a hurricane is 300 miles offshore but is threatening the coastline in moving inward. Should give expected movement, current location, and Max wind reported. Unscheduled, issued and updated as necessary.

ATIS. Automatic terminal service

Main purpose is to reduce radio congestion at the towered airport. Pre-recorded broadcast. Updated every hour with additional updates as needed. Winds magnetic heading and ceilings are AGL. Assigned the phonetic identifier

Sigmets significant meteorological information

Observations and forecasts. Can be hazardous to all aircraft. Issued as needed and valid for four hours unless it's a hurricane then valid for six. Specifically non-convective activity such as severe icing turbulence dust storms sandstorms clear air turbulence or volcanic ash

Airmets Airmens meteorological information

Observations and or forecasts. Issued every six hours and valid for six. Interest to all aircraft. potentially hazardous to smaller aircraft. Three types. Sierra for Mountain obscuration and IFR conditions. Tango for turbulence not associated with thunderstorms and surface winds in excess of 30 kn. Zulu for icing specifically moderate icing levels and freezing levels

Weather depiction chart

Overview of adverse and favorable weather conditions. Good for general weather conditions for cross country flight plans. Derived from METARs. No pressure systems or wind like surface analysis chart. Updated every 3 hours.

AWOS. Automated surface observation system

Provides automated minute by minute observation of weather conditions. Winds or magnetic and ceilings are agl Frequencies and phone numbers are in the AFD. Can be broadcast over calm or navaid frequencies.

Radar observations

Radar signals bounce off clouds and moisture and can give us a better idea of where they are located. Even at night. Great for determining visibility at various airports

Surface observations

Reporting stations are placed throughout the world on land and sea to record and transmit weather data. Mostly at airports

SPECI. Special METAR

Shows unscheduled update of significant change in weather conditions.

Surface analysis chart

Shows weather conditions for a valid period on chart. Shows fronts, pressure, patterns, temperature, winds, sky cover and precipitation. Updated every three hours

Satellite observations

Specialized weather satellites generate photos and also record temperature, humidity, wind and water vapor locations.

Convective outlook

Thunderstorm forecasting chart. Day one and day two forecasts. Describes areas of slight, moderate or high risk of severe thunderstorms or general thunderstorm activity. Day 1 issued 5 times a day. Day 2 issued twice a day. Day 3 issued once.

Pilot reports (PIREPS)

UAs, UUAs. Helpful to pilots that fly the same route. UAs include location, time, altitude, type of aircraft, clouds, visibility, weather, wins, temperature, turbulence, icing, and other remarks from pilots

Winds and temperature aloft forecast

Winds in relation to true north. 12 hour forecast at 0000z and 1200z Images have flags that show wind speed and direction. Textual will not have wind direction and velocity if the height block is within 1500 feet AGL and no temperature if within 2500 feet agl