Mountain Waves is defined as oscillations to the lee side (downwind) of a mountain caused by the disturbance in the horizontal air flow caused by the high ground.
The wavelength and amplitude of the oscillations depends on many factors including the height of the high ground above the surrounding terrain, the wind speed, and the instability of the atmosphere.
Formation of mountain waves can occur in the following conditions:
§ Wind direction within 30 degrees of the perpendicular to the ridge of high ground and no change in direction with height.
§ Wind speeds at the crest of the ridge in excess of 15 kts, increasing with height.
§ Stable air above the crest of the ridge with less stable air above and below that stable layer.
Vertical currents within the oscillations can reach 2,000 ft/min. The combination of these strong vertical currents and surface friction may cause rotors to form beneath the mountain waves causing severe turbulence.
Cassi Creek: the National Weather Service has posted a high wind advisory for tonight and tomorrow morning. Higher elevations may clock 30-40 sustained winds with gusts exceeding 60mph. While the foothills may not log sustained winds at those velocities, the formation of mountain waves is possible causing wind damage at lower levels by rotor-driven winds. The graphic above shows the mechanism for rotor formation.
The atmospheric conditions are conducive to thunderstorm formation in the Ohio and Tennessee drainages. There is a strong winter storm bringing heavy snow and winds to the plains states. The northern Appalachians may get snow while the southern Appalachians get more rain, possible thunderstorms, and possible severe storms.
We’ve had enough rain this month that the wet snow combined with wind might cause a lot of wind damage to trees, power and commo lines, and property.
The inclement weather is going to be particularly annoying tonight. I have a weather station fixed to the back deck that captures local conditions every 5 minutes for local logging, and every 15 minutes to upload to a nationa database. The program I upload to, Weather Underground’s Wundermap has been as very reliable and very user-friendly program for many years. It provides me with almost real time graphic reports from other local weather stations plus five minute loops of local and national radar for my purposes.
For some unknown reason, without warning subscribers, Weather Underground uploaded and installed a new revision of Wundermap. The timely access to local data and conditions is now unavailable. The program is ext to useless compared to its previous incarnation. I’ve made my displeasure known. I think that I may join the search for a better program to link with.
The potential for severe weather tonight and tomorrow has Gloria and I battening down what we can.
We plan on going into town sometime during the coming week for dinner at a Thai restaurant. Like many couples, we have a set of customs and quirks that are tradition for us. We celebrate this period in December, as it is when we first met. The initial meeting is, to our collective mind, very worthy of celebration. To that time, I had never seen such a blinding smile as the one that graced her face and lit up the airport terminal. I see it frequently now. Mornings and evenings are welcome events.
I think the winter project may be to encourage her to become familiar with the air rifle, then with the .22 lever action Henry. The firing lane is clear and we have the time to practice together. I need to put in some practice time as well. My atypical PD makes my ability to hold on target more difficult than ever before.
Yesterday we received a photograph of Olivia and Helena, Gloria’s nephew, David’s daughters. I’ve only seen the girls via Skype. It is a great photograph and Gloria is thrilled to have it. It was kind of David and Daisy to take the trouble to frame it and send it.
The NRA has begun their propaganda campaign. Their first official spin mentioned prayer, grief, mourning, tragedy, working to prevent such events in the future. Today’s Oliphant cartoon is more accurate a depiction of what I think is actually taking place in the corporate NRA offices.