1. National Weather Service Products
  2. Forecast Models
  3. Forecast Drivers 
  4. Forecast Confidence

National Weather Service Products

Comprehensive Displays

NWS Fire Weather and Enhanced Data Display - The National Weather Service’s (NWS) Experimental Enhanced Data Display (EDD) fills a void that currently exists in the NWS. It provides our partners and customers a single interface to access all things GIS related in the NWS. EDD is an extremely powerful and flexible GIS web application. Before the development of EDD, users had to navigate to countless web pages to get at the information they desired. EDD puts this information in one place making it very easy to display and manipulate this data. EDD is hosted on the National Internet Dissemination System (NIDS) and was developed by the Weather Ready Nation Pilot Project in Charleston, WV.

NWS Weather Prediction Center (WPC) - The WPC provides forecast products including quantitative precipitation forecasts and discussions, short-term and medium-range forecasts,  and surface analysis.

Short-Term Forecast Products (1-7 Days)

NWS Routine Fire Weather Forecasts - Updated generally twice a day, these narrative forecasts include a discussion of expected weather events, general weather parameters for the forecast zone over the next 48 hours, and an outlook summary for days 3-5.

NWS Watches and Warnings - General site provides access point to different products with map emphasizing different watches and warnings. Issuance of a warning or watch implies stronger confidence levels in growth conditions between 12-96 hours ahead of an event.

NWS Spot Weather Forecasts - This interface is intended to be used solely for the relay of forecast information to the National Weather Service. Submissions sent through this online form are intended for internal agency use.

National Digital Forecast Database (NDFD) and Wildand Fire Assessment System NDFD Point Forecasts (CONUS Only) - The NWS's NDFD graphic products are derived from a prescribed set of data contained within the NDFD. These graphics are representations of the official NWS digital forecast. Forecast information for the Canadian portion of the Great Lakes is for informational purposes only and does not constitute an official forecast. In CONUS only, WFAS provides a tool that allows NDFD forecasts to be queried for individual latitude-longitude locations.

NWS Storm Prediction Center - This Center provides timely and accurate forecasts and watches for severe thunderstorms and tornadoes over CONUS. The SPC also monitors hazardous winter weather and fire weather events across the U.S. and issues specific products for those hazards.

Extended Forecast Products (1 Week to Several Months)

NWS Climate Prediction Center Extended Outlooks - The Climate Prediction Center (CPC) is responsible for issuing seasonal climate outlook maps for 1-13 months in the future. In addition, the CPC issues extended range outlook maps for 6-10 and 8-14 days as well as several special outlooks, such as degree day, drought and soil moisture, and a forecast for daily ultraviolet (UV) radiation index. Many of the outlook maps have an accompanying technical discussion.

NWS Climate Prediction Center Expert Assessments - Includes Hazards Assessment, ENSO update, and others.  Climate Prediction Center (CPC) meteorologists and oceanographers review climate and weather observations and data along with model results and assess their meaning, significance, current status, and likely future climate impacts. Their findings are issued as assessments, advisories, special outlook discussions, and bulletins.

Drought Outlooks and Seasonal Climate Forecasts - These forecasts show predicted trends for areas experiencing drought depicted in the U.S. Drought Monitor, as well as indicating areas where new droughts may develop.

Forecast Models

Individual Forecast Models

National Centers for Environmental Prediction (NCEP) Model Guidance

  • Global Forecast Model (GFS)
  • European Computer Forecast Model (ECMWF)
  • North American Mesoscale Model (NAM)
  • Canadian Model (CMC)
  • Great Britain Computer Forecast (UKMET)
  • High Resolution Rapid Refresh (HRRR)
  • Weather Research & Forecasting (WRF)

Ensemble Forecasts

Ensemble weather modeling techniques have been developed which include multiple outputs or forecast members from the same deterministic model but perturbed or initialized with different observed conditions. Forecast skill can increase the first two weeks of a forecast period using these ensemble modeling systems.

Short-Range Ensemble Forecast (SREF) - The SPC Short-Range Ensemble Forecast (SREF)  focuses on diagnostics relevant to the prediction of SPC mission-critical, high-impact, mesoscale weather including: thunderstorms and severe thunderstorms, large scale critical fire weather conditions, and mesoscale areas of hazardous winter weather. 

High-Resolution Rapid Refresh (HRRR) for Short-Term Forecasts - The HRRR is a NOAA real-time 3km resolution, hourly updated, cloud-resolving, convection-allowing atmospheric model, initialized by 3km grids with 3km radar assimilation. Radar data is assimilated in the HRRR every 15 min over a one-hour period adding further detail to that provided by the hourly data assimilation from the 13km radar-enhanced Rapid Refresh.

North American Multi-Model Ensemble (NMME) for Long-Range Forecasts - The NMME is an experimental multi-model seasonal forecasting system consisting of coupled models from US modeling centers including NOAA/NCEP, NOAA/GFDL, IRI, NCAR, NASA, and Canada's CMC. The multi-model ensemble approach has proven extremely effective at quantifying prediction uncertainty due to uncertainty in model formulation, and has proven to produce better prediction quality (on average) than any single model ensemble.

Forecast Drivers

Teleconnections and Forcing Mechanisms

Coupled oceanic- atmospheric forcing mechanismsUsefulness and DefinitionConfidence Impact
El Nino Southern Oscillation (ENSO)Irregular periodic variation in winds and sea surface temperature over tropical eastern Pacific. Warming phase is El Nino and cooling phase is La Nina. There is also an ENSO neutral condition. Deep thunderstorm development over the eastern equatorial Pacific will help alter the jet stream and make more moisture available for Pacific storm systems that impact the USA.Warm or cool phases combined with other climate drivers such as certain phases of the PDO can lead to higher confidence long term outlooks.
Pacific Decadal Oscillation (PDO)A longer lived northern Pacific climate variability that has a negative and positive phase. The jet stream will tend to dip further south over the western United States under a positive phase and move further north under a negative phase.Positive or negative phases to the PDO combined with other climate drivers such as ENSO conditions can lead to higher confidence long term outlooks.
Pacific Meridional Model (PMM)Describes the interaction between ENSO and PDO teleconnections and has a negative and positive phase.Determining positive or negative phases of the PMM may help resolve the Spring Barrier issue and ENSO prediction. This should help lead to higher confidence outlooks originating during months of April through June.
ModokiAlternation in normal La Nina and El Nino SST patterns across the tropical Pacific thus disrupting typical teleconnection patterns. “This isn’t your grandfather’s El Nino”.Confidence becomes varied and can be less depending on other coupled ocean-atmosphere phenomena.
Madden Julian Oscillation (MJO)MJO is a tropical disturbance that propagates eastward around the global tropics with a cycle on the order of 30 to 60 days. They typically are most active during late fall, winter and early spring period. MJO can influence ENSO tendencies.Active MJO’s can increase forecast confidence for certain weather anomalies across USA.
Aleutian LowStrength of the Aleutian low combined with PMM modes can accentuate or dampen MJO impacts on the jet stream position and storm track across western USA.Confidence of an active storm track across western US increases when the Aleutian low is stronger than average and combines with a positive PMM and a MJO is present.

Forecast Confidence

The typical Confidence Horizon for an application requiring forecast information with "Very High" confidence/accuracy is about three days.  What is critical is that there are frequent shifts in this relationship that both expand and contract the amount of time that "Very High" skill is available, thus changing the Confidence Horizon.

Typical Forecast Confidence Horizon

This is especially helpful when choosing the appropriate analysis tool in WFDSS (Near-term, Short-term or FS Pro) or applying the weather forecast within them. The concept is also helpful when placing explanations in the analysis or incident notes section of WFDSS.

The atmosphere is chaotic but sometimes there is rhythm in the chaos. Climate outlook scientists study coupled oceanic and atmospheric forcing mechanisms like the El Nino Southern Oscillation (ENSO) cycle and Madden Julian Oscillation (MJO). These forcing mechanisms are tied to several teleconnection or long range-long term correlated weather patterns that determine meteorological impacts across North America.

Forecast skill typically goes up (i.e., rhythm in the chaos) in the mid and long term when certain forcing mechanisms and teleconnection patterns align, thus adjusting the normal Confidence Horizon. Under these circumstances, a monthly or seasonal outlook can have Medium to sometimes High confidence for certain weather patterns such as warmer and drier conditions and sometimes frequent wind events. This is a shift from Low to Very Low confidence under normal situations for longer-range forecasts.

Other teleconnection alignments can lead to mixed atmospheric forcing signals, thus leading to unusually low confidence periods (i.e., conflicting rhythm).

NWS Area Forecast Discussion - This NWS product is intended to provide a well-reasoned discussion of the meteorological thinking which went into the preparation of the Zone Forecast Product. The forecaster will try to focus on the most particular challenges of the forecast. The text will be written in plain language or in proper contractions. At the end of the discussion, there will be a list of all advisories, non-convective watches, and non-convective warnings. The term non-convective refers to weather that is not caused by thunderstorms. An intermediate Area Forecast Discussion will be issued when either significant forecast updates are being made or if interesting weather is expected to occur.



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