Part 83, page 4

Transcript

The scan is the source; the transcript is machine-generated from it.

KEY TO AVIATION WEATHER FORECASTS........

TERMINAL FORECASTS contain information for specific airports on ceiling, cloud heights, cloud amounts, visibility, weather condition and surface wind. They are written in a form similar to the AVIATION WEATHER REPORT.

CEILING: Identified by the letter "C" CLOUD HEIGHTS: In hundreds of feet above the station (ground) CLOUD LAYERS: Stated in ascending order of height VISIBILITY: In statute miles, but omitted if over 8 miles SURFACE WIND: In tens of degrees and knots; omitted when less than 10

---

SIGMET or AIRMET warns airmen in flight of potentially hazardous weather such as squall lines, thunderstorms, fog, icing, and turbulence. SIGMET concerns severe and extreme conditions of importance to all aircraft. AIRMET concerns less severe conditions which may be hazardous to some aircraft or to relatively inexperienced pilots. Both are broadcast by FAA on NAVAID voice channels.

WINDS AND TEMPERATURES ALOFT (FD) FORECASTS are computer prepared forecasts of wind direction (nearest 10° true N) and speed (knots) for selected flight levels. Temperatures are forecast for all levels shown except that no forecasts are issued for the 3000 ft. level or other levels within 2500 feet of a station's elevation.

---

EXAMPLE OF TERMINAL FORECASTS

C15⊕ Ceiling 1500', broken clouds O11/2GF Clear, visibility one and one-half miles, ground fog

.CSX1/4S+ Sky obscured, vertical visibility 500 ft. visibility one-fourth mile, heavy snow 200⊕C70⊕6K 3230G Scattered clouds at 2000', ceiling 7000' overcast. Visibility 6 miles, smoke, surface wind 320 degrees 30 knots, gusty

---

EXAMPLES OF WINDS AND TEMPERATURES ALOFT (FD) FORECASTS:

FD WBC 121745 BASED ON 121200Z DATA VALID 1300OZ FOR USE 1800-0300Z. TEMPS NEG ABV 24000

FT 3000 6000 9000 12000 18000 24000 30000 34000 39000

BOS 3127 3425-07 3420-11 3421-16 3516-27 3512-38 311649 292451 283451 JFK 3926 3327-08 3324-12 3322-16 3120-27 2923-38 284248 285150 285749

At 60000 feet ASL over JFK wind from 330° at 27 knots and temperature minus 8° C.

---

AREA FORECASTS are 12-hour forecasts plus 12-hour OUTLOOKS (18-hour outlook in FA valid at 1300Z) of cloud, weather and frontal conditions for an area the size of several states. Heights of cloud tops, icing, and turbulence are ABOVE SEA LEVEL (ASL); ceiling heights, ABOVE GROUND LEVEL (AGL); bases of cloud layers are ASL unless indicated. Area forecasts are amended by SIGMETs or AIRMETs.

---

PILOTS . . . report in-flight weather to nearest FSS DB Cooper-35325

---

U.S. DEPARTMENT OF COMMERCE • ENVIRONMENTAL SCIENCE SERVICES ADMINISTRATION • WEATHER BUREAU • Washington, D.C. • Revised MAY 1970

GPO : 1970 O - 404-111 For Sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402 Price 5 cents; $2.50 per 100