The information on the following pages is taken from

National Oceanic and Atmospheric Administration's
National Weather Service

US Dept of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
1325 East West Highway
Silver Spring, MD 20910

The National Weather Service states the following about the information on its servers.

Use of Data and Products

 The information on government servers are in the public domain, unless specifically annotated otherwise, and may be used freely by the public. Before using information obtained from this server special attention should be given to the date & time of the data and products being displayed. This information shall not be modified in content and then presented as official government material.

 The user assumes the entire risk related to its use of this data. NWS is providing this data "as is," and NWS disclaims any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will NWS be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of this data.

About Surface Analysis Charts

Surface analysis are produced manually every 6 hours and depict the locations of synoptic scale high and low pressure centers with associated surface fronts and troughs for the specific analysis time. Central pressure is depicted with 3 or 4 digits. Arrows point to the 24 hour forecast positions. The term "developing" gale or storm means gale or storm conditions are expected by 24 hours.

The pressure analysis has a 4 millibar (mb) contour interval. Forecast pressure values are written with 2 digits omitting the preceding 10 or 9. As an example a high pressure center with a central pressure of 1032 mb would be 32 and low pressure of 974 mb would be 74. For intense low pressure centers below 1000 mb, the analyst may use a dashed line to depict the 1000 mb isobar. By convention, isobars less than the 1000 mb dashed line are defined with an 8 mb contour interval.