1. Satellite Interpretation & Weather Patterns West of the Cascades Clinton Rockey Aviation Meteorologist

2. Types of Satellite Images VisibleInfrared Water VaporFog

3. Visible Images When Sun is up, clouds reflect the sunlight. So, clouds are visible. But, when sun goes down, what do we do? Can see land features Can see cloud details

4. Details Of Visible Images Typical Summer Afternoon

5. What Do You See? Typical Summer Afternoon

6. Visible Image Summary PROs: Shows topographic features Shows best detail of cloud features CONs: Not available at night See tops of the clouds only (can not tell if precipitation occurring) Can infer low to mid-level wind flow May be difficult to see clouds over snow covered terrain or layers of clouds.

7. Warmer the clouds, darker the shading. Colder clouds tops are white, and may be enhanced with color Cold Front, with Rain Cold Clear Air L

8. Strong Low Developing

9. Pineapple Express L H L L L

10. L 22 FEB 2007, 1 pm PST H L L

11. L H L L

12. L 23 FEB 2007, ~noon PST H L L L

13. IR Image Summary PROs: Shows cold and warm advection Good for determining areas of increasing or decreasing precipitation CONs: Best for night time use, but day is good Really cold air can often be mistaken for precipitation areas Good for showing developing or weakening storms

14. Water Vapor Image Moisture shows as gray/green areas. Dry air indicated by dark areas. Developing low, Along a front (rising moist air) Dry, sinking air L

15. L 22 FEB 2007, 1 pm PST L L H L

16. L 23 FEB 2007, noon PST L L

17. Water Vapor Image Summary PROs: Shows moisture/dry air advection (dry areas are candidates for fog and low level inversions) Good for detecting disturbances in the upper flow that may enhance/weaken low level inversions. CONs: Hard to determine areas of precipitation as same are could just be clouds Good for showing developing or weakening storms and fronts

18. Fog Image

19. Basic Weather Patterns West of the Cascades Marine pushes with stratus Radiation fog Thunderstorms and Virga Puget Sound Convergence Zone

20. Radiation Fog Key Ingredients: And, we need a low level moisture source Rapid Cooling Calm or Light Winds Clear/Mostly Clear Skies

21. Radiation Fog Formation Heat is transferred away from ground. This cools the air just above the ground. As temperatures cools, it will approach the dew point Temperature (Humidity goes up) As the air condenses into fog, the cooling continues as the cool air pool gets deeper.

22. Radiation Fog Dissipation

23. What Fog Looks Like Remember, Fog Hugs the Terrain, Sitting in valleys

24. What Fog/Stratus Looks Like Remember, Fog Hugs the Terrain, Sitting in valleys

25. Marine Surges/Push May through early October IFR initially, then transition to MVFR and eventually VFR Ceilings: Visibility: IFR on coast initially, then transition to VFR. Mostly VFR inland, but may have brief MVFR.

26. Northwesterly Marine Push Triggered by weak front or upper level disturbance arriving from Pacific Surface Winds are North to Northwesterly Shallow moisture layer on the Coast H H L L Characteristics… IFR on Coast, with Low MVFR inland Marine Layer about 1000 feet deep Evening

27. Northwesterly Marine Push Maintained by Surface High Pressure centered offshore Surface Winds are West to Northwesterly Gradually deepening moisture layer H H L Characteristics… IFR/MVFR on Coast, with MVFR inland Marine Layer about 2000 feet deep Latter Morning

28. Deeper Northwest Marine Push Maintained by Surface High Pressure centered offshore Surface Winds are West to Northwesterly Gradually deepening moisture layer H H L Characteristics… MVFR on Coast, with MVFR/VFR inland Marine Layer 3000-4000 feet deep Broken to Solid Stratocumulus over Cascades. Drizzle in mornings. Morning

29. Northwesterly Marine Push Maintained by Surface High Pressure centered offshore Surface Winds are Northwesterly Moisture layer shallowing. H H L Characteristics… Any clouds left will be VFR Marine Layer 3000-4000 feet deep Clouds Dissipating. May see a few Evening cumulus over the Cascades. Late Afternoon

30. “Puget Sound Convergence Zone”

31. MVFR VFR IFR VFR Puget Sound Convergence Zone…

32. Needs strong onshore flow Often provides sufficient lift… –to cause TS when conditions would otherwise be unfavorable. –Frequently gives IFR weather.

33. Convection Air in the free atmosphere will continue rising… –until it reaches a level where it is no longer buoyant. The more unstable the atmosphere… –the greater the convection.

34. Changing the Stability Three ways to increase/decrease stability: Upper Level Cooling Low Level Warming Increase in Atmospheric Moisture

35. Much Colder Air Aloft Offshore Cool, Unstable Air over Western WA/OR 22 FEB 2007, 1 PM PST

36. 23 FEB 2007, ~Noon PST

37. Convective Turbulence Avoid convective turbulence by flying above cloud tops… When possible. Smooth Ride Bumpy Ride

38. …the cloud will not continue to grow. Observations of Cumulus Clouds… If cumulus tops are ‘ragged’ and ‘ill- defined’

39. Virga…where is it? Is it safe to fly under this? Virga is a downdraft action Rain is evaporating but cool dense air is sinking to the ground. New Updrafts

40. Virga…where is it? Is it safe to fly under this? No updrafts. Cloud is in downdraft phase. Rain is evaporating but cool dense air is sinking to the ground.

41. If the cumulus tops are ‘crisp’ and ‘well defined’ …the cloud will continue to grow. Observations of Cumulus Clouds… DANGER: Fly too close and You may experience…

43. A B C D What do you see? E

44. November 1981 Windstorm

45. October 1962 Windstorm

46. Questions?