Figure 4-12.Symbols used on surface pressure and constant-pressure level analysis and prognosis charts.

from the National Weather Service. Products produced by processing data fields received from FNMOC must have a legend line (or lines) added across the bottom or top of the graphic identifying the information displayed. The legend line identifies the product using standard abbreviations and the valid time. For example, an analysis of the surface pressure data field of the 1800Z 12 December 1996 observation data may be identified with a legend line SFC PRESSURE ANALYSIS VALID 08DEC96 1800Z. The valid time is the UTC date/time that is represented by the information on the graphic. On some products, the valid time is identified with the designation VT: or the word valid; on other products, the date and time are just listed. In the case of an TERM SYMBOL COLOR Cold front at the surface BLUE Cold front aloft BLUE Cold front frontogenesis BLUE Cold front frontolysis BLUE Warm front at the surface RED Warm front aloft RED Warm front frontogenesis RED Warm front frontolysis RED Occluded front at the surface PURPLE Occluded front aloft PURPLE Stationary front at the surface RED AND BLUE Stationary front aloft RED AND BLUE Stationary front frontolysis RED AND BLUE Instability / Squall line PURPLE Trough axis BLACK Ridge axis BROWN Shear line BLUE Inter-tropical Convergence Zone RED Tropical Wave BLACK Jetstream core RED High Pressure/height center BLUE Low pressure/height center RED Tropical Depression center RED Tropical Storm center RED Hurricane / Typhoon center RED Figure 4-12.—Symbols used on surface pressure and constant-pressure level analysis and prognosis charts. 4-14