Weather 14th Annual Hot Air Balloon Safety Seminar

1. Weather 14th Annual Hot Air Balloon Safety Seminar Rick Davis Senior Meteorologist National Weather Service - Tampa Bay Area

2. Observing the Weather ASOS - Automated Surface Observing System Wind Direction and Speed Pressure measured at the Tower or other location nearby. Precip type and intensity Visibility Temp & Dew Point Data Unit Rain

3. ASOS Facts and Figures • 569 FAA sponsored sites • 313 NWS sponsored sites • Provides nonstop weather info, updating every minute if needed • Computer generated voice broadcasts gives pilots updates critical to safe landings • Using FAA VHF ground-to-air radio or appended to ATIS broadcast • Information is also available through the phone or on the internet

4. AWOS Automated Weather Observing System • AWOSs cost about $94,000 and are much less expensive than ASOSs • Who owns them • Federal AWOSs are maintained by the FAA • Most AWOSs are owned and maintained by states, airports, or other local interest • There are three main types of AWOSs • AWOS I - temp, dew point, pressure, wind, density altitude • AWOS II - adds visibility • AWOS III - adds cloud information • AWOS IIIp - adds precipitation type sensor

5. ASOS/AWOS Locations Florida

6. Decoding METARs Winter Observations METAR KTPA 101955Z 33015G22KT 1/2SM FG VV002 19/19 A2955 RMK A02 PK WND 32035/1915 TWR VIS 3/4 SLP028 P0004 T01920188 Temp = 19.2 C Dew = 18.8 C 00.04" rain in last hour Sea level pressure 1002.8 MB Tower visibility 3/4 mile Peak wind northwest at 35kts at 1915Z Automated precipitation reporting Remarks

7. Aviation ForecastsTafs/Twebs From NWS in Ruskin KFMY KRSW

8. Decoding TAF Forecasts Some Insights TAF AMD KFMY 141542Z 141612 33030G40KT 2SM RA B KN010 TEMPO 1618 32035G44KT 3/4SM +TSRA SQ BKN008 OVC015CB FM1800 32025G32KT P6SM BKN020 TEMPO 1821 .... - Most detail is in first 12 hours, generalized outlook after 12 hours - Issued four times a day at 06Z, 12Z, 18Z, and 00Z - Format of each forecast group is wind, weather, clouds - Naming of present weather has a strong French influence - GR is hail >1/4 inch - GS is hail < 1/4 inch - FU is smoke

9. Weather Balloons The Radiosonde • Launched at the same time across the world (11Z & 23Z) • Rises 1000 feet per minute • Reaches 90,000 ft in 1.5 hours • Balloon expands to 35 feet before exploding • Measures: • Temperature • Dew Point • Wind direction and speed • Pressure

11. Radiosonde Data Station Map and Data Plot

12. Doppler Radar

13. Doppler VAD Wind Profiles Velocity Azimuth Display

14. General Winds • Large-scale winds caused by the pressure patterns associated with high and low pressure areas.

15. Fronts & Instability IR satellite image overlaid with radar and fronts

17. Wind Flow Associated With Pressure Systems and Fronts • Wind direction ahead of an approaching low pressure system and cold front will generally be southerly. Wind Speed will normally increase ahead of approaching systems. • Wind direction behind a cold front and low pressure system will become northerly. Wind speed will normally be stronger just behind the front, then will slowly decrease.

18. Sources of Lift Fronts and Low Pressure Systems L H 70s 60s 80s Cold air weighs more than warm air

19. Local Winds • Smaller-scale winds caused by local temperature differences.

20. Seabreezes • During a clear day. . . sunshine heats the land to a greater extent than the water. • Warm air over the land rises and is replaced by cooler, moister, marine air.

22. Sea Breezes (cont’d) • An area experiencing a sea breeze will see: • A temperature decrease 5-7o F. • An RH increase of 10-15 %. • A possible change in wind speed and direction. • Thunderstorms in unstable air.

27. Localized Thermals cumulus cloud that may form due to rising air reaching dewpoint Cooler Sinking Air Bubble of Warm Air

28. Air Motion Stability = Vertical Motion Wind = Horizontal Motion

29. Wind Shear • Two Types of Wind Shear • Directional Shear - Wind direction varies with height. • Speed Shear – Wind speed significantly increases with height. • BOTH ARE IMPORTANT TO AVIATION!!!

30. Instability Parcel Theory • A parcel is a small bag of air (size of cubic foot) • Acts like a hot air balloon • Doesn’t let air in or out • The bag will rise if it is warmer than the surrounding air • The bag will sink if it is colder than the surrounding air

31. Parcel Theory Parcels act like bags of air 50̍ at 10,000 ft 70̍ at 5000 ft 90̍ at surface A I r T e m p e r a t u r e 70̍̍ Will this parcel rise or sink? The parcel will rise because the air inside the parcel > air outside (70̍ > 60̍) Will this parcel rise or sink? 70̍̍ The parcel will sink because the air inside the parcel < air outside (70̍ < 80̍)

32. Instability Relating to Temperature Inversions 50̍ 60̍ 85̍ 80̍ 90̍̍ 10,000 feet Stable Layer 82̍̍ 92̍̍ Surface What happens when temperatures warm with height? (a temperature inversion)

33. Instability Sea Breeze and Outflow Boundaries 50̍ 60̍ 80̍ 88̍̍ 50̍ 60̍ 70̍ 85̍ 80̍ 90̍̍ 10,000 feet 55̍̍ 63̍̍ 72̍̍ Stable Layer 82̍̍ Sea Breeze 92̍̍ Surface Need lifting mechanism to get parcel above inversion

34. Unstable Atmosphere

35. Stable Atmosphere

36. Unstable, But No Storms? Why is that? Stable Layer Need additional lift to get thunderstorms to develop

37. Atmospheric Stability • Stability is a measure of the equilibrium of the atmosphere to vertical motion. • Stable Air - Resists Vertical Motion • Unstable Air - Encourages Vertical Motion

38. Stability Continued • Paramount to the concept of stability is: • Relative to the surrounding environment: hot air rises and cold air sinks.

39. Remember that indicators of stable and unstable atmospheres are instantaneous indicators. Changes in stability can be extremely rapid.

40. Stability is a function of the Lapse Rate • Change in temperature with height

41. Average Lapse Rate Decrease of 3.5 degrees F per 1000 feet of altitude 66.6o 1,000’ H 70o T

42. Lapse Rate and Stability • If the measured lapse rate is greater than 5.5° F per 1000 ft, the atmosphere is unstable. • If the measured lapse rate is less than 5.5° F per 1000 ft, the atmosphere is stable. • If the measured lapse rate is equal to 5.5° F per 1000 ft, the atmosphere is neutral.

43. Inversions Layer of air in which the temperature rises with height. 3 Types Radiation or Nighttime Inversion Marine Inversion Subsidence

44. Temperature Inversions • As you go aloft, temperature normally decreases at a rate of 5.5° F. per 1000 feet. • Temperature inversion occurs when the temperature increases with height instead of decreasing.

45. Temperature Inversions Dewpoint Temperature

47. Inversions • Inversions normally dissipate as the surface temperature rises and mixing of the atmosphere begins, unless inversion is strong. • Inversions frequently occur near the center of high pressure systems where winds are light and skies are clear.

48. Mixing Height • The height below which relatively vigorous mixing in the atmosphere is taking place • Winter Daytime 2- 4 Thousand Feet • Summer Daytime 4-6 Thousand Feet • Nighttime/early morning 100-500 feet when stable to 1000 feet in unstable

49. Transport Winds • Average horizontal wind speed and direction between the surface and the mixing height. • Determines the rate of horizontal movement.