Over the past several years, the NWS has developed the Interactive Forecast Preparation System (IFPS), which allows the forecaster to prepare a forecast using gridded information. It provides a new way to present and develop better marine forecasts at the Weather Forecast Office (WFO).
Using IFPS has changed the way forecasters are doing marine forecasts. Before IFPS, forecasters would typically examine the models, develop their forecast then translate the wind and seas forecast into a worded product. With IFPS, the forecast process has become more detailed and methodical. The first step usually begins with populating an objective wind analysis into the gridded database, and then incorporating model forecast output. Second, one or more numerical grid fields are loaded into the database and a weighting smart tool is often used to produce a model consensus, or to put more emphasis on one model over another. The third step involves populating wave model output from the NOAA WaveWatch III model into the wave grids. Forecasters then use the Graphics Format Editor (GFE) associated with the IFPS to improve on model output. Other forecaster derived grids can search for wind and sea values that meet hazard criteria helping forecasters pinpoint when and where watches, warnings or advisories are necessary over the forecast domain.
On many occasions in the Northeast Florida and Southeast Georgia coastal waters, the Global Forecast System (GFS) model does not accurately reflect nocturnal southwest flow events, which are usually between 15 to 25 knots, during the summer months,. Therefore, adjustments in the wave grids are almost always needed because the GFS is the primary wind input to the Western North Atlantic Wave model (WNA). This WNA wave model is one of the subsets of the general NOAA wave model. The gridded guidance has helped forecasters identify these model biases and make improvements to the forecasts. Wave models also suffer some skill is in the nearshore waters where shoaling and wave dissipation are difficult to model. The forecaster can now apply this knowledge with a gridded database to develop improved forecasts that benefit the marine community.
The implementation of IFPS has resulted in significant changes in the Great Lakes marine forecasting process and its end products. Unlike in the past when a forecaster subjectively determined the best wind forecast over the Near Marine Zone (NMZ), IFPS allows the forecaster to graphically display the winds at all points over the entire NMZ. Winds are a very important component of wave forecasting on the Great Lakes and the GLERL wave model. Using IFPS and this wave model, with detailed forecaster derived wind and stability fields as input, has resulted in significant improvement in wave forecasts on the Great Lakes.. On the West Coast of the United States, IFPS has revolutionized the way marine forecasts are created as well as the way these forecasts can be used by marine customers. Up to seven different sets of grids are use to describe the sea state in the NWS Western Region. These parameters are wind (direction and speed), wind wave height, swell, swell period and combined sea height. Also, during mixed swell episodes, a secondary swell train may be described using the swell2 and period2 grids. With all these different parameters available in gridded format, a very detailed depiction of the sea state can be communicated to the educated marine customer. The increased amount of information available to the mariner is superior to what was conveyed via text forecasts prior to IFPS.
Various "smart tools" are available to forecasters with the GFE for manipulating marine grids. For example, the "pencil tool" allows the forecaster to edit gridded data with a high degree of precision. Also, the "model/forecast blend" tool works well in allowing the forecaster to blend the current forecast grids with newer model runs. Thus this blend tool is serving as a highly effective technique for adjusting the current forecast towards the latest model guidance. The "Text Formatters" are used to generate the text forecasts from the gridded database. Editing of the automatically generated text is sometimes necessary in order to highlight varying conditions in certain portion of a marine zone, for example, higher conditions near a particular point or cape. The use of "local effects" tools in the formatters establishes areas of persistent localized conditions that vary from the predominant conditions.
Nearshore wave models are also under testing on the west coast that can incorporate winds grids from forecasters to produce detailed winds wave and swell forecasts. The nearshore models are being nested in order to provide bar forecasts for the often treacherous harbor crossings.
These IFPS forecasts are becoming more important given the proliferation of Internet access by mariners at home, at the marina (via Wifi and marine weather kiosks), and while on the near shore waters via air cards. The grids are also displayed as "snapshot images" on the Web. These images show a more detailed depiction of the forecast conditions than the single range of values given in the traditional worded Coast Waters Forecast. The grids can also be displayed as meteograms, and IFPS output can help with specific forecasts for ports and marinas with a high concentration of commercial/recreational marine traffic. Overall the use of IFPS has created a new way of presenting and developing better marine forecasts at the WFO level.
The IFPS marine forecasts can be viewed at the following Web sites:
National marine graphical forecast page:
http://www.nws.noaa.gov/forecasts/graphical/sectors/conusMarineWeek.php#tabs --for the National Marine graphical forecast page;
A WFO scale graphical wave forecast:
http://www.weather.gov/forecasts/graphical/sectors/southcaliforniaMarineWeek.php#tabs --showing graphical wave forecast on the WFO scale;
WFO Jacksonville marine forecasts:
http://www.srh.noaa.gov/graphical/sectors/jaxMarineDay.php#tab
Graphical wave input from the Great Lakes:
http://www.weather.gov/forecasts/graphical/sectors/centgrtlakesMarineDay.php
Information provided by: The marine section of the Specialized Operational Services Committee…Hugh McRandal…Andrew Shashy…John Taylor…Ross Van Til, and John Lovegrove