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About scottd

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    : Charlotte, NC
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    Weather, writing, flying

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  1. scottd


    Here's the RAOB that they used to determine the 201 knot wind (231 mph). It was at 33,000 feet.
  2. scottd


    Theoretically it's very easy. It's an optimization problem to maximize your groundspeed based on the forecast winds aloft. You'd have to limit the altitude by the service ceiling or oxygen requirements. But again, that's easy. Practically, it's not so easy as there are weather barriers that will create a less than optimal route on most days. We're looking at the best wind alternative now in WeatherSpork that will also include weather routing based on forecasts. But that's a ways off.
  3. scottd


    What’s your question?
  4. scottd

    Got into ice today

    Sleet is the colloquial term. Ice pellets are produced through a different process than hail. Ice pellets are a great indicator of SLD aloft as I will be explaining at my live webinar in March.
  5. scottd

    Yikes, cold thunder!

    What's a slew-t chart? Ah, a sKew-t chart.
  6. scottd

    Yikes, cold thunder!

    Pretty amazing area of thunderstorms here that spans a very large area. Here are the convective SIGMETs (red polygons) shown in WeatherSpork and the yellow area is the convective outlook. Why is this amazing? Not because it's in the middle of February and there's thunderstorms, but because there really isn't any instability in the regions where convection is now occurring as indicated by the most unstable CAPE chart below. It's all in association to a very large high amplitude upper level trough moving in from the west. There's this cold wedge of air sitting up over the lower Mississippi and Tennessee Valley area. If you look at the surface winds through Tennessee, northern Alabama, northern Mississippi, they are all out of the east bringing in some very cold, moist air as air flows clockwise around the high pressure in the east. Then, if you go up to 5,000 feet (850 mb) below notice the wind direction...from the south over the Gulf coast states. Even some winds as much as 50 knots. We call this isentropic lift as that warm air moves up and over the dense air at the surface. So essentially this air is riding up on the density discontinuity.
  7. Temperature 3°C at the surface and thunder. KCHA 192053Z 35011KT 2SM TSRA BR SCT007 SCT015CB OVC060 03/02 A3040 RMK AO2 TSB35 SLP296 OCNL LTGIC SW-N TS SW-N MOV NE Translated: YUK!
  8. Jeff, The part that is a shame is that they filter the mosaic. I'd personally rather see an unfiltered depiction. Yes, it will have ground clutter and anomalous propagation on it, but it'll also show you the location of gust fronts and outflow boundaries that are currently filtered out. And it won't miss these events.
  9. I can't be sure without doing some detailed investigation and getting TWC (formally WSI) involved to find out. However, it smells like an issue that isn't all that common, but not all that rare. I discuss this here in my new AvWxTraining blog (feel free to join my blog - its free and you'll get notified of new posts). Also if you are an AvWxWorkshops/WeatherSpork member, I discuss this issue also in one of my bite-sized member workshops here.
  10. FZUP - some kind of unknown freezing precipitation I guess. Or someone FZ'ed it UP!
  11. scottd

    Foreflight MOS Down?

    If there’s no weather reports, you won’t see a MOS forecast. Likely they may be using the nearest MOS for this airport. MOS is more than extrapolation. Here’s a video that explains more about MOS.
  12. scottd

    Foreflight MOS Down?

    There was a change of some government URLs are now requiring https vs http. It likely has something to do with that.
  13. scottd

    The ultimate Getthereitis?

    That's a good point and the reason I mentioned it. Too many pilots (and briefers) tend to overlook that. Understanding the criteria for when a convective SIGMET is issued is critical. There doesn't have to be a convective SIGMET for an area of convection to be extremely dangerous. Plus there were a ton of other clues in that TAF pilots need to learn how to interpret.
  14. scottd

    The ultimate Getthereitis?

    I agree that the big picture is the most important. I make most of my decisions to go or stay based on that big picture, not the details. I don't talk to a briefer any more except to get NOTAMs or file a PIREP or flight plan. Primarily because they don't provide (or are allowed to provide) some of the higher temporal and spatial resolution tools that are now available and have been for over a decade. They basically stick to a script (defined in AC 00-45H Change 1) which works very well when the weather is extremely challenging (no fool would launch) or extremely benign (even the most junior pilot would launch). It's that "in between" weather scenario where I've seen a briefer provide less than stellar information. In the end, it comes down to understanding how the forecasts and observations should be interpreted. What does SHRA (rain showers) really mean if the visibility is 5 statute miles? Does that WS020/18045KT (non-convective LLWS) mean a really bad ride for my early morning flight? The briefer isn't going to tell you fact, in my experience they are more likely interpret it the wrong way. There's no harm to call a briefer. Just be aware, there are open manholes in that briefing. When I do one-on-one training with a student for a trip that he or she is about to take, I often take about an hour. Most telephone briefings are typically less than 10 minutes (maybe 15). That's simply not enough time to get a true sense of all of the factors that should play into your decision. Plus, the briefing is a very single threaded approach. You provide a departure time (and other stuff) and then you get flooded with weather data. Instead, I like to look at all possible departures over the next few days and see which time gives me the best opportunity to minimize my exposure to adverse weather. Once I have that time (assuming it fits in my schedule), then I drill down to understand the details.
  15. scottd

    The ultimate Getthereitis?

    Perhaps, but based on the thousands of pilots I've trained over the last 20 years, there's a lot more to the story when you dig deep. In this case there were thunderstorms in the area. Here's the 17Z observation: KPBI 011653Z 12003KT BKN045 BKN060 21/20 A3021 RMK AO2 RAE40 SLP229 CB E-SE MOV N CB DSNT S P0001 T02060200 And the 18Z observation: KPBI 011822Z 00000KT RA BR SCT012 BKN041 21/20 A3017 RMK AO2 CB OHD-NE-E MOV N CB DSNT NE SE P0006 T02110200 Here's the TAF for nearby PBI - KPBI 011459Z 0115/0212 VCSH SCT025 TEMPO 0115/0117 SHRA FM012200 07008KT VCSH SCT020 BKN050 FM020400 11010KT SCT020 BKN070 I wish this pilot had attended my most recent webinar. The TAF above clearly illustrates the dangers he was facing - but few pilots know how to interpret this (and no, it's not about decoding the TAF, but understanding the threats clearly depicted. I wish that more pilots would read the has so much good info most of the clearly indicates the potential for embedded convection. .AVIATION... Convection associated with a weak frontal boundary meandering across South Florida's Atlantic waters will continue to create periods of sub-VFR conditions over the next day or so. PBI is the terminal most likely to be impacted this afternoon with MVFR or brief bouts of IFR/LIFR conditions possible. Low cigs/fog is possible overnight, mainly in SW Florida and over the interior, which will possible affect APF into Saturday morning. Additional convection on Saturday could again create sub-VFR conditions mainly along the east coast. The route was on the southern edge of a convective outlook area, but there wasn't a convective SIGMET issued because the convection did NOT meet SIGMET criteria. The news story said he flew into a severe thunderstorm. There wasn't a severe thunderstorm in this area. Ugh!