Transcribed Weather Broadcasts (TWEBs) are meteorological and aeronautical data recorded on tapes and broadcasted continuously over selected low/medium frequency navigational aids and/or VHF Omni-Directional Range (VOR) equipment
Provided mainly in Alaska
Part of a series of individual taped recordings which are changed as they occur
Content:
The information provided varies depending on the type equipment available
Generally, the broadcast contains route-oriented data with prepared National Weather Service (NWS) forecasts, a summary of adverse conditions, surface weather observations, pilot weather reports, and a density altitude statement (if applicable)
At selected locations, telephone access to the TWEB has been provided (TEL-TWEB)
Numbers are found in the Alaska Supplement of the Chart Supplement U.S.
TWEB Frequencies Listed in the Chart Supplement U.S.
Issuance & Validity:
Issued 4 times daily (0200Z, 0800Z, 1400Z, and 2000Z)
Valid for 12 hours
TWEB Route Forecast:
249 TWEB 251402 KISN-KMOT-KGFK. ALL HGTS AGL XCP TOPS. KISN-50NM E KISN TIL 00Z P6SM SKC...AFT 00Z P6SM SCT050 LCL P6SM -TSRA BKN050. 50NM E KISN-KDVL TIL 20Z P6SM SCT070...AFT 20Z P6SM SCT070 LCL SFC WNDS VRB35G45KT 3-5SM TSRA CIGS OVC030-040. KDVL-KGFK TIL 16Z P6SM SCT-BKN020 AREAS 3-5SM BR...AFT 16Z P6SM SCT040
249 - Route number
TWEB - TWEB Route Forecast
25 - twenty-fifth day of the month
1402 - Valid 14Z on the twenty-fifth to 02Z on the twenty-sixth (12 hours)
KISN-KMOT-KGFK - Route from Williston, ND to Minot, ND to Grand Forks, ND
Translation:
All heights AGL except cloud tops. KISN-50NM E KISN until 00Z, visibility greater than 6 SM with clear skies. After 00Z, visibility greater than 6 SM with scattered clouds at 5,000' AGL. Local areas of visibility greater than 6 SM, thunderstorm with light rain showers, and broken clouds at 5,000' AGL. 50 NM E KISN-KDVL (Devil's Lake, ND) until 20Z, visibility greater than 6 SM, scattered clouds at 7,000' AGL. After 20Z, visibility greater than 6 SM, scattered clouds at 7,000' AGL, local surface winds variable at 35 gusting to 45 knots, visibility 3-5 SM, thunderstorm with moderate rain showers, overcast ceilings 3,000-4,000' AGL. KDVL-KGFK until 16Z, visibility greater than 6 SM, scattered to broken clouds at 2,000' AGL, areas of visibility 3-5 SM with mist. After 16Z, visibility greater than 6 SM, scattered clouds at 4,000' AGL
TWEB Vicinity Forecast:
431 TWEB 021402 LAX BASIN. ALL HGTS MSL XCP CIGS. TIL 18Z P6SM XCP 3SM BR VLYS BKN020...18Z-22Z P6SM SCT020 SCT-BKN100...AFT 22Z P6SM SKC
431 - TWEB vicinity number
TWEB - TWEB Forecast
02 - second day of the month
1402 - valid 14Z on the second to 02Z on the third (12 hours)
LAX BASIN - The weather conditions in the Los Angeles basin
Translation:
All heights mean sea level except ceilings. Until 18Z, visibility greater than 6 SM except 3 SM due to mist in the valleys and broken clouds at 2,000' MSL. Between 18Z and 22Z, visibility greater than 6 SM and scattered clouds at 2,000' AGL; also scattered to broken clouds at 10,000' MSL. After 22Z, visibility greater than 6 SM and sky clear
A TWEB synopsis forecast is a brief description of the weather systems affecting the route during the forecast valid period. The synopsis describes movement of pressure systems, movement of fronts, upper air disturbances, or air flow
TWEB Synopsis:
BIS SYNS 250820. LO PRES TROF MVG ACRS ND TDA AND TNGT. HI PRES MVG SEWD FM CANADA INTO NWRN ND BY TNGT AND OVR MST OF ND BY WED MRNG
BIS - Bismarck, ND, WFO issuing synopsis and route forecasts
SYNS - Synopsis for the area covered by the route forecasts
25 - twenty-fifth day of the month
1402 - Valid from 08Z on the twenty-fifth to 20Z on the twenty-fifth (12 hours)
Translation:
Low pressure trough moving across North Dakota today and tonight. High pressure moving southeastward from Canada into north-western North Dakota by tonight and over most of North Dakota by Wednesday morning
Conclusion:
Broadcasts are made available primarily for preflight and inflight planning, and as such, should not be considered as a substitute for specialist-provided preflight briefings