Fundamentals of Forecasting (Lynn P. Maximuk)

NWS Digital Services

Understanding Violent WeatherFundamentals of Forecasting

Lynn P. MaximukMeteorologist In ChargeWFO Pleasant Hill, MO

October 24, 2005


IT Has Changed The Weather Forecast World

• The NWS primary product is information – not text messages

• Partners and customers demand more of the most current information possible, available when they want it

• High resolution graphical and tabular data for improved service


Digital Forecast Goals• Leverage national and local expertise to:

• Provide high resolution forecast information• Ensure meteorological consistency• Focus on high impact events• Provide Information in multiple formats


National Digital Forecast Database (NDFD)

• Multiple input sources – Time and Space• WFOs • National Centers

HPC/SPC/CPC/AWC/NHC/TPC etc.• NWS product – not local office product

• Offices produce a piece of the product• Meteorological consistency a must• One stop shopping


Digital Data

• Will continue to evolve• Add a vertical dimension• Watch and warning information• Observational information• Climatological information

• Tap into GIS capabilities• Readily useable formats


Modern Technology

• New ways to prepare forecasts by depicting the underlying forecast information

• Flexibility extracting information to meet partner and customer needs – formats without bounds

• Ability for rapid updates



Service and Information Flow

• Frequent updates in short term – hourly• High spatial resolution – 5km nationally

and 2.5km locally• More detailed forecast information for

weather parameters important to partners and customers to feed their formatters and decision software


How to Obtain NDFD Data

• Data, decoders and detailed information available at the following web sites:• Weather.gov/ndfd• Weather.gov/ndfd/technical.htm

• Database contents, format, etc.• Available in GRIB2, NetCDF and XML


Data Extraction Ideas

The Sky is the Limit!



Traditional Forecast Format


Detailed Forecast Information


Decision Aid



Polygon Warning Experiment

• Warnings were issued for the ‘threat area’ of a storm, counties fell out as needed from this threat area.

• Extensive outreach on key issues conducted spring 2005.

• Multiple warnings in effect for a county.• Impact on EAS• How to ‘visualize’ the polygons?


Polygon Warning Experiment

• Customer feedback:• Many emergency managers expressed that

one of the reasons they rated services improved this year was because of the refined ‘box’ used in warnings.

• Some radio stations lukewarm (especially with regard to tornado warnings and EAS), as they get more warnings for the same ‘county’.


Media perspective on polygons

• Cones Of “StormTracks” are already familiar with viewers

• Text Crawls already cut whole county warnings

• Challenge is to marry audio message with new video display

• Learning curve with Media and NWS


Polygons in action

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Fundamentals of Forecasting (Lynn P. Maximuk)