Pressure Patterns
When you live near or in the mountains you learn the positions of high and low pressure areas in your locality.
In the Northern Hemisphere (North of the Equator) high pressure cyclonic motion is "clockwise" (looking down on the rotation it moves from left to right.)
A low pressure cyclonic motion is "counter "clock-wise" (looking down on the rotation it moves from right to left.
For example, if a high pressure area is moving in from the NW to the SE and a low pressure area is leaving from the SE and moving E what could happen if you flew from the SW to the NE between the two fronts?
As the two fronts proceed on their respective paths, the "clock-wise" rotation of the winds from the high pressure moving in merges with the "counter-clockwise" rotation of winds from the low pressure area moving eastward.
They combine to produce very high, turbulent winds. If you are flying between them you will experience strong head winds and experience a very bumpy ride over the Appalachian Mountains.. (The West doesn't have all the mountain ranges to themselves, only the youngest)
Where I live, south of the Smokey Mountains in the Up State area of South Carolina (Near Clemson University) the wind patterns are affected by the mountainous terrain) Our weather has a mind of its own when compared to the state.
Make it a point to know your own flying location. You need to make plans based on that knowledge.
Mountain Waves and Lenticular Clouds
When winds aloft reach 30 to 35 MPH and flow at right angles to ridges the wind is deflected, in such a way, to form clouds that appear to look like water rushing over a trout stream. These are mountain waves. These waves form downwind from the ridge and are formed from very strong updrafts and downdrafts. Without enough moisture to form clouds this is called CAT. (Clear Air Turbulence) Running into CAT can stress a plane beyond its limits and a possible breakup of the plane may occur.
If enough moisture is in the air the mountain waves are visible. This gives you early warning to avoid the area until conditions change or subside.
In the flatlands the formation of visible air waves look like the lens in a glass lens. The flow could be laminar (smooth) or turbulent. (rough) They form quite high an the flatlanders don't worry about their effect on their planes.
Roll Clouds in front of a thunderstorm are different. If caught in one your plane, regardless of power, will crash into the ground from the very strong rotating air.
Flight planning will help you sort out the best route to fly to accomplish your goal.
Winds in Passes
Winds speed up when passing through a pass. Any time wind speeds up obstacles will create turbulent flow of air. The turbulence will produce very powerful updrafts and downdrafts. The climbing power of an aircraft may not out-perform the downdrafts. Stay away from turbulence in mountainous terrain.
Learning mountain flying is hard. Take one little bite each time and soon the task is done.
