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Weather Product Definitions

FORECASTS

In addition to forecasts, this section includes statements, advisories, watches, and warnings. Discussions, outlooks, and guidance are also in this section.

  • Forecast - Expected weather and hydrologic conditions.
  • Statement - Update current weather situations or highlight significant changes to come. Also used to explain why watches, advisories, or warnings have been issued.
  • Advisory - Issued for non-life threatening weather that is expected to be a disruption to the normal routine, and, if caution is not exercised, could lead to situations that may threaten life and/or property.
  • Watch - Used when the risk of a hazardous weather event has increased, but its occurrence, location, and/or timing is still uncertain. Generally, the probability of occurance is greater than 60%.
  • Warning - A hazard is imminent and the probability of occurrence is extremely high. Used for conditions posing a threat to life or property.
  • Discussion - Background information on current conditions or evolving trends.
  • Outlook - A hazardous weather event may develop. Intended to provide information to those who need considerable lead time to prepare for the event. Generally, the probability of occurance is greater than 30%.
  • Guidance - Information from models provided for planning purposes only, as values may contain significant uncertainty due to future weather and/or reservoir regulation. Actual conditions may be significantly above or below those described.

WFO products in this section:

  • Zone Weather Forecast - Expected weather conditions within a zone forecast area through seven days. Weather conditions include headlines, precipitation and probability of precipitation forecasts, sky condition, temperature, wind, and visibility restrictions. The first 36 hours reflects the observed and imminent weather conditions, with an emphasis on details and timing. (NWSI 10-503)

  • Coastal Weather Forecast - Wind, wave and weather conditions between the coastline and 60 miles offshore. (NWSI 10-310)

  • Area Forecast Discussion - Narrative issued routinely at least 2X per day, but is usually issued more frequently to provide reasoning for forecast updates or to provide an explanation of rapidly-evolving trends. (NWSI 10-503)

  • Tabular 7-Day Forecast - General forecast in tabular format of hydrometeorological conditions over a WFO forecast area of responsibility for the next 7 days. (NWSI 10-503)

  • Hazardous Weather Outlook - Designed to be a "Heads Up" to expected hazardous weather and its potential impact. A hazard is defined as a weather, hydrologic, or non-precipitation event that has a significant chance of creating a harmful impact on people. (NWSI 10-517)

  • Flash Flood Warning - Issued when flooding is imminent. Reserved for those short-term events which require immediate action to protect lives and property, such as dangerous small stream flooding or urban flooding, and dam or levee failures. (NWSI 10-922)

  • Flood Warning/Small River and Stream Flood Warning - Any high flow, overflow, or inundation not covered by flash flood warning. (NWSI 10-922)

  • Flood Statement/Urban and Small Stream Flood Advisory - Statement issued to follow up flood warnings. Contains supplemental information on previously issued flood warnings, such as updated observations and impact information. Advisory issued to address non-warning "nuisance" type flooding. (NWSI 10-922)

  • Flood/Flash Flood Watch - Hydrometeorological conditions which may cause flooding when the flooding is neither certain nor imminent. (NWSI 10-922)

  • Winter Storm Watch/Warning - When conditions are favorable for a hazardous winter weather event to develop over part or all of the forecast area, but the occurrence is uncertain or when hazardous winter weather is occurring, imminent, or has a high probability of occurrence over part or all of the forecast area. (NWSI 10-513)

  • Short Term Forecast - Detailed weather information during significant and/or fast changing hydrometeorological conditions. (NWSI 10-517)

  • Special Weather Statement - Information concerning ongoing or imminent weather hazards. (NWSI 10-517)

Regional products in this section:

  • Basin QPF - QPF, or Quantitative Precipitation Forecast, represents the average amount of liquid precipitation, in inches, expected during a specified period, typically 6 or 24 hours, throughout specified basins in the forecast area.

  • Point QPF - QPF, or Quantitative Precipitation Forecast, represents the total amount of liquid precipitation, in inches, expected during a specified period, typically 6 or 24 hours, at specified points in the forecast area.

  • Hydrometeorological Discussion - Hydrology-oriented overview of the current and expected hydrometeorological situation across the RFC area. (NWSI 10-912)

  • Flash Flood Guidance - Numerical estimate of the average rainfall over a specified area and time interval required to initiate flooding on small streams. (NWSI 10-912)

  • Headwater Guidance - Numerical estimate of the average rainfall over a specified small stream basin and time interval required to initiate flooding on the stream. (NWSI 10-912)

  • State Weather Forecast - General forecast in narrative or tabular format of hydrometeorological conditions over a regional forecast area of responsibility for the next 7 days. (NWSI 10-503)


SUMMARIES

In addition to summaries, this section includes observations.

  • Summaries - Aggregated hydrometeorological data.
  • Observations - Hydrometeorological data.

WFO products in this section:

  • Precipitation for Recent 1, 2, 3, 6, 12, 24 hours - Local precipitation data for time periods specified. (NWSI 10-912)

  • Regional Temperature/ Precipitation/ Snow Depth Summary - Maximum/minimum temperatures and 24-hour precipitation totals from designated reporting stations. (NWSI 10-501)

  • Daily Climatological Summary - Daily climatological report. (NWSI 10-501)

Regional products in this section:

  • Precipitation Summary (Automatic Gages) - Precipitation data from automated gages. (NWSI 10-922)

  • 6-Hourly and 24-Hour Precipitation Summary - Quality-controlled precipitation data for specified time periods. (NWSI 10-922)

  • River Stage Summary (Automatic Gages) - River stage data from automated gages. (NWSI 10-922)

  • State Weather Roundup - Routine, standardized hourly weather observations. (NWSI 10-501)

  • Statewide Temperature/ Precipitation/ Snow Depth Summary - Maximum/minimum temperatures and 24-hour precipitation totals from designated reporting stations. (NWSI 10-501)


Source: http://www.weather.gov/directives/010/010.htm