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Instrument Refresher Course

Instrument Refresher Course. Overview. Seasonal Patterns Climatology Flight Hazards Lightning Icing Turbulence METAR/TAF Code 25 th Operational Weather Squadron Products. SEASONAL PATTERNS. H. Wind Flow. Surface. L. Upper Air. Seasonal Patterns. Four Corners High.

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Instrument Refresher Course

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  1. Instrument Refresher Course

  2. Overview • Seasonal Patterns • Climatology • Flight Hazards • Lightning • Icing • Turbulence • METAR/TAF Code • 25th Operational Weather Squadron Products

  3. SEASONAL PATTERNS

  4. H Wind Flow Surface L Upper Air Seasonal Patterns Four Corners High Spring / Late Summer Pattern: Hot and Dry Weather

  5. L Wind Flow Surface Upper Air Seasonal Patterns Mid-Latitude Storm H Fall, Winter, Spring Pattern: Rain, Snow, Wind Producer

  6. Wind Flow Surface L Upper Air Seasonal Patterns California Cut-Off Low Winter-Spring Pattern: Rain and Wind

  7. L Wind Flow H Surface H L Upper Air Seasonal Patterns Monsoonal Flow Summer Pattern: Thunderstorm Producer

  8. Summer Weather Pattern Winds shift from dry Westerly to moist South-Easterly direction Moisture, heat, thermal lift over mtns Avg monsoon start: 7 Jul

  9. The Monsoon Difference Pre-Monsoon = Hot and Dry What a difference a wind shift makes! Monsoon = Hot, humid, and Thunderstorms

  10. CLIMATOLOGY

  11. Average Temperatures

  12. Thunderstorms Days

  13. Average Rainfall

  14. FLIGHT HAZARDS

  15. Flight Hazards • All thunderstorms are hazardous to all aircraft • Thunderstorms always imply: • Severe/Extreme Turbulence • Severe Icing • Low-level Wind Shear • Lightning • Hail

  16. Mature Stage Dissipating Stage Cumulus Stage Rain Light Rain Unstable Airmass plus Trigger Downdraft shuts off updraft Intense localized Downdraft Possible Microburst = Airflow Circulation Thunderstorms

  17. Thunderstorms Cumulus Stage--Towering Cumulus Sharply defined edges More vertical extent than horizontal

  18. Thunderstorms Mature Stage--Cumulonimbus Distinct anvil Rain starts to fall

  19. Thunderstorms Microburst • SHORT LIVED WIND EVENT • VISUAL CLUES • DUST AND DUST RINGS ON SURFACE • RAIN SHAFTS AND CURLING RAIN • THUNDERSTORMS

  20. Wind Flow Gust Front Thunderstorms Microburst Dust ring on surface

  21. Lightning

  22. Lightning • Where can you find it: • Within 8°C of the freezing level • 5,000 feet of the freezing level • In light precipitation (including snow) • In clouds (including debris clouds) • In light or negligible turbulence

  23. Lightning • How can you tell if a charge is building up on your aircraft? • St. Elmo’s Fire • Light Precipitation • Static on your radio

  24. Lightning • 2nd leading cause of direct weather deaths • Kills more than hurricanes and tornadoes combined! • Kills ~ 100 / year • Kills ~ 5% of those struck • Elusive data • 30 - 50% under-reported

  25. Lightning can jump off an object into another nearby object - Just one of many reasons NOT to be near trees in a thunderstorm Side Flash Lightning

  26. Lightning Damage - U2 Aircraft induced lightning strike

  27. Hail • Often found under the Anvil • Has been encountered as high as 45,000' MSL • May be carried up to 20 miles downwind • CANNOT SEE ON RADAR, unless inside a storm

  28. Hail

  29. Hail Damage - Navy S3

  30. TURBULENCE

  31. TURBULENCE • JETSTREAM • Occurs near Jetstream and Tropopause • Worst below and on the low pressure side of jet • SHOWERS/CONVECTIVE ACTIVITY • MDT-SVR TURB can occur

  32. TURBULENCE • THERMAL • Associated with heating, rising air, and different surfaces heating at different rates • Mostly light, occasional moderate, surface to 10,000 feet • Calm or light winds aid in heating • Most prevalent in late afternoon to early evening • Local areas of occurrence: Across rough terrain from surface to 5,000 feet when temperatures > 90

  33. TURBULENCE • MOUNTAIN WAVE • Most severe type of terrain induced turbulence • Caused by stable air with strong winds crossing mountain barrier • Extends up to 40,000 feet • Occurrence of Intensities: • Severe- up to 150 miles leeward of ridge • Moderate-as far as 300 miles leeward • Can identify by cloud types: cap, rotor, lenticular

  34. MTN WAVE TURBC CLOUDS LENTICULAR STRONG WINDS CAP CLOUD MOUNTAIN RANGE ROTOR

  35. LENTICULAR CLOUD

  36. Mtn Wave Turbc in NV and UT--rippled clouds

  37. ICING

  38. ICING • RIME (Between 0 and -20 C): • - Rough, milky, and opaque • - Forms when super-cooled droplets freeze on contact with aircraft • - Stratus clouds • CLEAR (Most Dangerous, Between 0 and -10 C): • - Glossy, clear layer of ice that forms after large super-cooled droplets spread over the aircraft before freezing • - Cumulus clouds • MIXED: • - Combination of the two--usually occurs in unstable clouds between (-9 and -15 C) • *Icing should not occur at temperatures below -22C

  39. A B ICING ALONG A COLD FRONT Flight Path A: Icing Threat Possible Flight Path B: Significant Icing Threat Likely

  40. ICING INTENSITIES • Trace - Icing barely perceptible • Light - Rate of accum could be hazardous after 1 hour (Deice used) • Moderate - Rate of accum hazardous after short time • (Deice frequently used) • Severe - Rate of accumulation is so severe deice/anti-ice is not effective

  41. METAR &TAF Codes

  42. METAR Code KDMA 281959Z 34007KT 210V350 50SM FEW050 BKN080 12/M01 A2996 RMK SLP132 MTN TOPS OBSCD NE WND DATA ESTMD; METARs will always be in this order KDMA – Airfield Identifier 281959Z – Date and time of observation, 28 day of the month at 1959Z 34007KT – Wind direction and speed are 340 degrees at 7 knots 210V350 – Wind is varying between 210 and 350 degrees (not reported if wind is not varying) 50SM – Prevailing visibility is 50SM FEW050 BKN080 – Sky condition is Few at 5000ft and Broken at 8000ft AGL 12/M01 – Temp is 12 degrees C, Dewpoint temp is -1 degree C A2996 – Altimeter Setting is 29.96” RMK – remarks, these can include any information the observer feels is operationally significant SLP132 – Sea level pressure is 1013.2mb MTN TOPS OBSCD NE – mountain tops are obscured to the NE WND DATA ESTMD – wind data is estimated

  43. TAF Code KDMA 281313 VRB06KT 9999 BKN050 BKN080 620755 590004 QNH2990INS BECMG 1819 28009KT 9999 SCT050 BKN080 620804 QNH2988INS BECMG 2021 28012G18KT 9999 FEW120 QNH2985INS WND 28010KT AFT 00 BECMG 0405 15006KT 9999 SKC QNH2989INS T14/23Z T06/13Z; First line: 281313 – date and valid time of the forecast, 28 day of the month, valid between 1300Z and 1300Z the following day VRB06KT – wind forecast 9999 – unlimited visibility, visibility expected is encoded in meters in military TAFs BKN050 BKN080 – sky condition 620755 – icing group, light icing from 7,500 to 12,500ft. Note, last number in the group denotes the THICKNESS of the layer 590004 – turbulence group, severe turbulence from the surface to 4,000ft. Note, last number in the group denotes the THICKNESS of the layer QNH2990INS – lowest altimeter expected between 281300Z and 281900Z is 29.90”

  44. TAF Code KDMA 281313 VRB06KT 9999 BKN050 BKN080 620755 590004 QNH2990INS BECMG 1819 28009KT 9999 –RA BKN050 BKN080 620804 QNH2988INS BECMG 2021 28012G18KT 9999 NSW FEW120 QNH2985INS WND 28010KT AFT 00 BECMG 0405 15006KT 9999 SKC QNH2989INS T14/23Z T06/13Z; Second line: BECMG 1819 – weather transitioning between 281800Z and 281900Z. Expect following weather to be predominant after 1900Z. -RA – present weather, in this case, light rain. - denotes light, + denotes heavy, no descriptor, moderate. Other confusing present weather codes: BR (mist), FU (smoke), PL (ice pellets), GR (hail). VC – vicinity (between 5 and 10 miles away) Third line: WND 28010KT AFT 00 – After 290000Z, expect winds to change to 280 degrees at 10 knots NSW – no significant weather Fourth line: SKC – skies clear of any clouds. If you see CLR, denotes clear skies below 12,000ft. T14/23Z T06/13Z – expect high temp of 14 degrees C at 282300Z, low temp of 6 degrees C at 291300Z. The first to occur, high or low, will be encoded first.

  45. 25th Operational Weather Squadron • Provide 24 hour weather support in the form of: • Forecast Warnings • Flight Hazard Forecasts • Flight Weather Briefings • https://ows.dm.af.mil/

  46. Forecast Watches & Warnings Watches Lightning w/i 5nm (lead time: 30 min) Warnings Tornado (lead time: 30 min) Winds ≥ 50kt (lead time: 120 min) Hail ≥ 3/4" (lead time: 90 min) Surface Winds ≥ 35kt < 50kt (lead time: 90 min) Hail ≥ 1/2" < 3/4" (lead time: 90 min) Heavy Rain (≥ 2" in 12 hours) (lead time: 90 min) Observed Warning Lightning w/i 5nm

  47. Web Page Products Turbulence Icing Thunderstorms Forecasts available for 00 – 48 hours Via the 25th OWS website FL Wind/Temp VFR/IFR Conditions

  48. WEB PAGE https://ows.dm.af.mil/

  49. QUESTIONS?

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