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Prediction in the Short Term
 Some of the most threatening weather events—gusty thunderstorm
winds, ice on highways and aircraft, turbulence aloft—are the
toughest to predict. They may affect only a small area, and they
can develop and dissipate within minutes. With the right guidance
in hand, meteorologists can issue "nowcasts"—short-term
forecasts that outline how local weather will evolve in the next
few hours.
Specialists at NCAR have created software packages that track the
unfolding of such hazardous, short-fuse weather events. Many of these
products are FAA-supported. Several are part of the Aviation
Digital Data Service, a popular Web-based
tool developed at NCAR. The products also rely heavily on fast-updating
computer models, such as the Penn
State/NCAR mesoscale model (MM5).
Below are a few of the areas where NCAR-produced software is making
a difference in short-term outlooks.
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Thunderstorms
The Auto-nowcaster takes
radar, satellite, and weather-station data and projects the
movement and evolution of thunderstorms over a one-hour period. |
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Turbulence
The new Graphical Turbulence Guidance product gives
easy-to-understand predictions of in-flight turbulence to aviation
forecasters, airline dispatchers, and pilots. NCAR has also designed
airport-specific software to detect and predict turbulence and
wind shear at airports in the United States and abroad, including Hong
Kong International Airport. |
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In-flight icing
The FAA and NWS have approved the use of the Current
Icing Product and Forecast Icing Product, both developed
by an NCAR-led team. These products have shown superior skill
in diagnosing and forecasting locations of in-flight icing conditions.
Using fuzzy-logic techniques, the software combines observational
data with weather-model output. Research is now under way to
enhance the system so it predicts not only the presence of icing
but also its severity. |
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Ceiling and visibility
Low ceiling and poor visibility contribute to more than
a third of all weather-related accidents in U.S. civil aviation.
NCAR is leading a national team to produce better forecasts of
both. A test
system provides forecasts each hour, with updates
as needed every 15 minutes. |
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Toxin dispersal
NCAR has studied how short-term computer models can
be combined with specialized observations—for example,
data from radar and lidar (laser-based radar)—in order
to predict
the motion of potential airborne toxins. This work
is aimed at protecting high-risk military and civilian targets. |
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Oceanic weather
Much of the weather over Earth's oceans goes unreported.
For instance, high cloud cover often keeps satellites from detecting
thunderstorms below. NCAR
researchers are working on automated
systems to better classify satellite-sensed cloud cover (including
clouds related to thunderstorms) and to detect turbulence and
volcanic ash. |
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Wildfires
Collaborative research involving NCAR's Wildland
Fire Collaboratory Initiative has led to models that extrapolate
fast-changing fire behavior. The team is now exploring how to
incorporate data on land use and vegetation using Geographic
Information Systems technology. This is a critical step in producing models that will eventually help both firefighters and meteorologists. |
Along with these applied products, NCAR generates basic research on the
workings of weather in the short term. For instance, a long-running line
of research has clarified the factors that result in different types
of thunderstorms. These types include weak, short-lived cells; narrow,
fast-moving squall lines; isolated supercells that pack large hail or
tornadoes; and mammoth storm clusters that dump swaths of heavy rain. Training tools derived from this research now help forecasters decide
how and when to warn the public as storms evolve.
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