Tuesday, February 26, 2008

Weather Issues

Hi All,

I am in the Atlanta area, waiting to get down to southern Florida to pick up a passenger. Unfortunately, the weather is not cooperating with our plans. We use a WSI (not sure what it stands for) computer terminal shown to the right.

WSI Pilotbrief provides a complete solution including WSI NOWrad® national and regional radar, radar summary charts, high-resolution satellite imagery, plotted SIGMETS, AIRMETS, and more. It's the choice of the nation's top FBOs, FAA Flight Service Stations and corporate flight departments.
Our picture is shown to the left. As you can see, there is a white box shown between Atlanta and Miami. The white boxes signify a SIGMET.

Wikipedia: SIGMET, or Significant Meteorological Information, is a weather advisory that contains meteorological information concerning the safety of all aircraft. There are two types of SIGMETs, convective and non-convective. The criteria for a non-convective SIGMET to be issued are severe or greater turbulence over a 3000 square mile area, or severe or greater icing over a 3000 sq mile area or IMC conditions over a 3000 sq mile area due to dust, sand, or volcanic ash.

A Convective SIGMET is issued for convection over the Continental U.S. Convective SIGMETs are issued for an area of thunderstorms affecting an area of 3000 sq miles or greater, a line of thunderstorms at least 60 nm long, and/or severe or embedded thunderstorms affecting any area that are expected to last 30 minutes or longer.

Above and to the left are closer pictures. The one to the left has red boxes - which signifies tornado watches! Sorry they're hard to see, that's the flash of the camera.
This weather system hit us early this am in Atlanta, and has been moving slowly across the country. The weather picture on the computer can be "looped" so you can see the movement over time. It gives pilots a good idea of how fast the system is moving, and if it's building or lessening. This colorful one is generating severe thunderstorms (hail, turbulence, high wind gusts). Green is light rain, and as the colors go from there to yellow to red (there's even purple), the precipitation (and associated storm characteristics) get worse. Flying through yellow is uncomfortable. Red is bad. Purple, well, we don't want to go there. Ever. (Of course, there are people who fly through storms for a living. That's not my gig.)
So, we're continuing to analyze, to see if the storm will break up or move on by (it hasn't been moving very fast). Remember how I said in a previous post that "we're going to go eventually anyway?" We have a couple of options in such situations. We can either pick our way through and around, or wait. Sometimes it pays to stay safely on the ground!
I know our passenger is restless, wanting to be on his way. Unfortunately, this is a safety issue. There's been reports of severe turbulence (again, severe turb is NOT to be flown through). We can't do that much deviating either, because it burns up so much fuel. We may risk painting ourselves into a corner. Again, people pay pilots to keep them safe. It's our job.

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