NCEP Newsletter

About 96 Hr Surface Forecast

The forecast positions and strength of the tropical systems wind speeds will be based on the latest warnings from the Tropical Prediction Center's (TPC) National Hurricane Center (NHC) , which covers the Atlantic and the Eastern Pacific Oceans east of 140W, and the Central Pacific Hurricane Warning Center (PHNL) covering the Eastern and Central Pacific Ocean west of 140W to the international dateline (180), and the Joint Typhoon Warning Center (JTWC), covering the Western Pacific west of 180.

These surface forecast products generated once each day from 12Z based forecast model guidance or previous versions with additional guidance from a variety of sources such as the ECMWF, UKMET, and NAVYs Navy Operational Global Atmospheric Prediction System (NOGAPS).  The use of several numerical models allows adjustments to be made to the final forecast product. The products show surface isobars every 4 mb with labeling of 2 digits in increments of 8 mb. The central pressure millibar values of synoptic scale lows and highs in bold 3 or 4 digits are underlined adjacent to or under the "L" or "H". The 72-hour forecast position and future 120-hour forecast position of lows and highs have vector arrows with an "X" for low centers and a "circle with an X inside" by the head for high centers. An underlined bold two digit mb central pressure value will be placed under or adjacent to the 72/120 hour position label (e.g.,1050 mb high would be written as a 50 and a 960 mb low would have 60). The 96-hour surface forecast depicts wind speeds in knots (wind barbs in increments of 5 or 10 knots) for areas of wind in excess of 33 knots, and frontal systems (occluded, warm, and cold). Significant systems have labels depicting whether the system is expected to have "gale" , "storm", or hurricane force conditions. If 120 hour forecast gale, storm, or hurricane force conditions are expected, the appropriate area has the label "developing gale" , "developing storm", or " developing hurricane force".