Weather 9/1/07 Full text

Or more like weather education. I've posted information I use to help figure out the day. Often I'll also post graphics with explanations of "why" the weather guessers think the day is good.

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Weather 9/1/07 Full text

Post by dcutter » Sat Sep 01, 2007 9:06 am

Well folks, these are some mighty interesting days. I have several reports with the highest altitude of 8300ft on Friday. One very detailed report supplies the how/why for that altitude. Before you read the following report and forecast WARNING. We are on the edge of a "Black Sunday" event. Think Icarus, except when you try to touch the thunderhead, you freeze, solid. OK, first a quote from NWS discussion this morning. "The air mass will continue virtually unchanged with temps nearly 20° above normal in the mountains and 10 to 15 decress above normal in the valleys." That means there was a widespread inversion yesterday which NWS expects again today. Another quote from NWS... "Weak descending flow over Ventura Co and areas northward is expected, while weak to moderate ascending flow is expected to redevelop over Los Angeles Co. today." My guess is the usual descending flow over the transverse ranges that creates the Catalina Eddy, for some reason, turns into ascending flow, like a wave, over LA Co. The only reason I can see, was the giant thunderhead over Palmdale on Friday. So I think above the inversion the thunderstorm was sucking the descending air back up into the desert. What felt like a convergence was really this ascending flow. We can confirm this if people with wind direction instruments can verify flow direction in this lift. If it's a convergence we should see wind directions on either side pointing toward the convergence line. If it's this ascending flow, we should see wind direction going the same way on either side of the imagined convergence line. Please remember my warning above. TODAY... I have reason to believe that the Tstorm activity will be closer to us today than yesterday. The inversion is still present but much lower and I suspect will be less or no issue. I see temps being 5° hotter. We also have more NW wind in the picture. Today may not go like yesterday I think we are closer to the Black Sunday line than yesterday. I recommend not trying the above experiment or you are likely to find yourself in air that you can't get out of. The blipspot shows a Boundary level top at 12,600ft at 7am which is now lower at 12,500ft. I suspect that's possible for a max altitude today but, if you get there you;re going to be in a world of hurt. I'm staying home today. Although I'm considering hanging out in the LZ. Reports to <a>Cutter</a> or by phone (626) 260-1615 Thanks!

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Gust Fronts

Post by frosty » Sat Sep 01, 2007 10:58 am

As always, watch out for any CuNim's in the area. In the last 2 days at Crestline/Marshall, 35+ mph gust fronts hit the Andy Jackson LZ in the afternoon. The gust fronts originated at a CuNim about 25 miles away.


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Re: Gust Fronts

Post by stebbins » Sat Sep 01, 2007 1:10 pm

Frosty wrote:As always, watch out for any CuNim's in the area. In the last 2 days at Crestline/Marshall, 35+ mph gust fronts hit the Andy Jackson LZ in the afternoon. The gust fronts originated at a CuNim about 25 miles away.

Yep. That's what Dave means by Black Sunday. We had similar issues a few times in the past. Less often than you guys at Crestline, but occasionally. And often they are preceded by the best, smoothest, highest lift you've ever seen at Kagel. Then you die. OK, figuratively speaking. But it suddenly gets very good just before it gets dangerous. Last time it happened (Brown Sunday) I ran away and flew past Fillmore. If you aren't low enough to get down before the gust front, then running is safer. Heck, the dry wash that runs past the Magic Mountain amusement park to Fillmore has lots of room to land. Way better than fighting the gust front, as lots of folks did on Brown Sunday.

(And, yes Cutter, I know Brown Sunday had different weather causes than Black Sunday, but the effects and safe corrective actions are the same.)
Fly High; Fly Far; Fly Safe -- George

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