The System for
and Nowcasting (SCAN)
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)
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?
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
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.
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