1. The art of weather forecasting
Will it rain tomorrow?
The art of weather forecasting

2. Agenda Measuring all of that air – current conditions
Observing sites, Weather Buoys, Satellites, Radar, & Radiosondes (aka weather balloons)
Using the past to predict the future –computer modeling
Putting it all together – forecasting
Sign me up! I want to be a meteorologist too.

3. Measuring all of that air

4. Measuring all of that air
Knowing current atmospheric conditions is essential for weather forecasting
This includes both surface conditions as well as the atmosphere aloft.
The major means of making these measurements include:
Surface observing stations
Weather buoys
Satellites
Radar
Radiosondes

5. Surface Observing Stations
The oldest form of measuring the weather.
Stations around the world measure & report current weather conditions (temperature, wind, rainfall, cloud cover, etc.).
This includes staffed, volunteer,
as well as remote reporting
stations.

6. These measurements give us our surface maps

7. Now wait a minute!
The earth is covered mostly in water. How do you know what’s going on in the oceans?

8. Surface conditions on water
Weather buoys are uses to remotely report ocean surface conditions.
Ship measurements are also used.
Ocean measurements are spotty.

9. Weather Satellites Look at the entire globe

10. Weather Satellites
Weather satellites allow for a view of the entire globe.
Though not able to measure conditions directly, they provide a vast amount of information indirectly.
Three major types of images:
Infra-red
Visible light
Water vapor

11. Infra-red satellite images
Measures the temperature of clouds
The colder the cloud, the higher it is

12. Visible light satellite images
Shows what the naked eye would see
Only available from sunrise to sunset

13. Water vapor satellite images
Shows amount of water vapor, not just clouds
Good for following atmospheric circulation

14. Radar Seeing what’s going on in the clouds

15. Radar Radar shows where cloud & precipitation are
Gives both horizontal and more importantly, vertical positions.
Gives movement information as well as precipitation intensity.
Helps in determining rain/ice/snow lines

16. Radiosondes (weather balloons)
Note the attached parachute
Measuring the actual conditions in the upper atmosphere

17. Radiosondes
In manty cases, lifted by hydrogen filled (cheaper than helium) balloons
Radiosondes measure:
Temperature
Relative humidity
Pressure
As they rise, wind speed and direction information is derived from the balloon’s movements.

18. Radiosondes Information gathered is radioed back.
Movement determined by GPS. Directional radio antennas (old school method) are sometimes used more so outside of the U.S.
Launched twice a day
in the U.S.

19. Radiosonde launch network
The nearest launch site is on Long Island

20. Radiosondes
The balloon grows in size as the atmospheric pressure decreases.
Eventually, the balloon bursts
A small attached parachute helps slow the fall of the radiosonde.
If found, radiosondes can be mailed back and are refurbished or salvaged.
Less than 20% are returned.

21. Let’s see how a launch is done

22. Radiosondes don’t always come back in the best of shape.

23. Other times they do
Radiosonde
Balloon remnant
Parachute

24. Using upper air data
Radiosonde data is used to create the upper maps, like the 500mb map.

25. Using upper air data
Provides temperature, moisture and wind changes at all levels of the atmosphere
This data is also used to determine the stability of the atmosphere.
Understanding atmospheric stability is extremely useful in determining the potentials for severe weather.

26. Source: National Center for Atmospheric Research
Skew T, Log P diagrams
Plots temperature and moisture (dew point) and wind data.
A major tool in forecasting severe weather.
Source: National Center for Atmospheric Research

27. Letting the machines do the work for us.
Computer Forecasting
Letting the machines do the work for us.

28. Computers in Forecasting
Computers are a major component in modern weather forecasting.
Quickly generate all of those maps and charts of current conditions.
With historical weather data, used to model the atmosphere which allows for the forecast models forecasters rely on heavily.

29. Computer Forecast Models
Modern superfast computers have made for the rapid growth in forecast modeling possible
Short term (looking ahead 6 hours) forecast modeling is used to help predict severe weather, snow storms, etc.
No single forecast model is “best”.

30. Weather Forecast Models
Often forecasters compare a few models to develop their forecast.
Forecast models include:
Long term (days)
Global Forecast System (GFS) – North American
European Centre for Medium-Range Weather Forecasts (ECMWF) - European
Short term (hours)
North American Mesoscale Forecast (NAM)
Rapid Refresh Model (RAP)

31. “The computer does not understand these things.”
-- Tetsuya “Ted” Fujita
tornado expert
developer of the F-scale for tornadoes

32. Forecasting is really an art
Forecasters use all of the available data to generate their forecasts.
Computer forecast models can not do it all… yet.
Past experience is relied upon.
Sometimes you just need to look out of the window and see what the weather is like.

33. How do I become a weather forecaster?

34. Becoming a meteorologist
Meteorology uses a lot of physics & math.
A minimum of a bachelors degree is needed.
An advanced degree is really needed to move up in the field.
Meteorology is not just forecasting:
Broadcasting
Climate
Research
Forensics

35. Thank you for your attention. Does anyone have any questions?