SCAN FACT SHEET

WHAT IS SCAN?

SCAN stands for System for Convection Analysis and Nowcasting. Convection is a mechanism for heat transfer. In the atmosphere, convection can produce rising air currents and thunderstorms. SCAN is a sophisticated, state-of-the-art software package being developed by the National Weather Service (NWS) for its Advanced Weather Interactive Processing System (AWIPS). SCAN detects, analyses, and monitors thunderstorms and generates short-term forecasts and warning information for severe and tornadic thunderstorms and flash floods. SCAN is a tool to help warning forecasters make better decisions.

WHAT ARE THE GOALS OF SCAN?

The goals of SCAN are:
-To provide NWS forecasters with accurate, timely, and consistent severe weather and flash flood information
-To develop "smart" computer displays that present the information forecasters need to know when they need it most.
-To supplement hazardous weather monitoring done by human forecasters with automated monitoring.
-To accelerate the rate of technology transfer from research to operations and external users

WHAT ARE THE BENEFITS OF SCAN?

The benefits of SCAN are:
-Longer lead times on warned events
-Fewer missed events
-Increased forecaster situational awareness
-Reduced forecaster fatigue during warning situations
-Digital and graphical products for external users
-A well-defined focus for applied research

WHY DO FORECASTERS NEED SCAN?

The amount of data available to forecasters in the modernized NWS is enormous. AWIPS receives billions of bits of radar, satellite and lightning data every few minutes. Information overload for forecasters can be a real problem during critical weather situations when knowing what to look at and why can make the difference between issuing timely warning that saves peoples' lives and issuing no warning at all.

WHAT IS THE SCAN VISION?

SCAN will be a weather watch dog for the NWS forecasters, monitoring the AWIPS database every few minutes and alerting forecasters to rapidly evolving thunderstorms and their associated hazards (damaging hail, winds, tornadoes, lightnings, and flash floods).

No Storm Undetected, No Weather Hazard Unwarned.

WHO IS DEVELOPING SCAN?

SCAN is being developed by the NWS's Meteorological Development Laboratory (MDL) in Silver Spring, Maryland. Sub-Components of SCAN are being developed by: (1) NOAA's National Severe Storms Laboratory (NSSL) in Norman, Oklahoma, (2) National Center for Atmospheric Research (NCAR) in Boulder, Colorado, (3) the NWS's Hydrologic Research Laboratory in Silver Spring, Maryland, and (4) NOAA's Forecast Systems Laboratory in Boulder, Colorado

WHAT ARE THE MAJOR COMPONENTS OF SCAN?

1) SCAN/WARNING DECISION SUPPORT SYSTEM (WDSS)

NSSL's WDSS represents a series of severe weather detection and prediction algorithms, data integration techniques and innovative display concepts for meteorologists to use during severe warning operations. During the past four years, NSSL has tested the WDSS in 18 NWS Forecast Offices across the country and has received very positive feedback on its utility. Because of this feedback, the WDSS has become destined for incorporation into AWIPS within SCAN

2) SCAN/THUNDERSTORM AUTO-NOWCASTER

Every five minutes, NCAR's Thunderstorm Auto-Nowcaster produces a forecast of where thunderstorms are likely to be located in 30 and 60 minutes. The Thunderstorm Auto-nowcaster processes primarily radar and satellite data to identify where thunderstorms are currently located with respect to each other and to other important features like wind shift lines generated by thunderstorm downdrafts. The Thunderstorm Auto-Nowcaster uses computer artificial intelligence techniques to generate its forecasts.

3) SCAN/FLASH FLOOD MONITORING AND PREDICTION

The flash flood monitoring and prediction component of SCAN is focused on using the NEXRAD radar to automatically estimate how much rain has fallen into small steams and rivers. If enough rain falls in a particular stream over a short enough period of time, a flash flood can occur. There may be over 3,000 such small streams over the area of responsibility of a single NWS forecast office. SCAN will automatically monitor every one of these streams every five minutes and alert the forecaster when a flash flood may be eminent in any one of them.

WHAT IS ON THE HORIZON FOR SCAN?

New software packages based on SCAN are being planned to provide forecaster decision assistance for other weather hazards:

SAFESEAS: Forecasting and warnings over marine and coastal areas
SAFEAIR: Forecasting and warnings in support of aviation
SAFEFIRE: Forecasting and warnings for wild fires and controlled burns
WINTERx: Forecasting and warnings for winter storms.

WHAT RECOGNITION HAS SCAN RECEIVED?

- Dr. Stephan B. Smith of the NWS Techniques Development Lab received a 1998 NOAA Adminstrator's Award for creating and developing SCAN.

- JT. Johnson formerly of NOAA's National Severe Storms Lab received a 1997 Department of Commerce Bronze Medal for forecasting support provided to the 1996 Atlanta Olympics with their Warning Decision Support System.

-Components of NCAR's Thunderstorm Auto-Nowcaster are being tested for use by the U.S. Army and the Federal Aviation Administration.

-Mike Eilts formerly of NOAA's National Severe Storms Lab received a 1998 NOAA Adminstrator's Award for his positive impact on research initiatives including development of the WDSS

POINTS OF CONTACT:

Dr. Stephan B. Smith, NWS, 301-713-1774 x180
Rita Roberts, NCAR, 303-470-8480

OFFICE OF PUBLIC AFFAIRS

HOW THUNDERSTORM WARNING DECISIONS ARE MADE WITH SCAN