TIP (Thermal Index Prediction) USER EXPERIENCE
How soaring pilots use the TIP for their flights

These postings are intended to help TIP users benefit from other's knowledge, by describing how pilots are empirically using the TIP based upon their actual flight experiences.  I have added some words in brackets based upon my understanding of the user's posting (submitters: let me know if I'm wrong!).


HOLLISTER and AVENAL  Ramy Yanetz  May 22, 2001
[For flying out of Hollister] I use the Avenal TIP instead of Hollister especially on high pressure days with a strong low-level inversion like we had the last couple of weeks.  The TIP for Hollister is miserable compared to the Avenal one, and indeed there was hardly any lift in the Hollister valley.  The reason for the difference is obviously the marine layer, but it is completely blocked 25 miles away from Hollister on the east side of the Diablos.  So if someone really wants to soar these days, all he needs is to look at the Avenal TIP and take a high tow and glide 25 miles to Panoche where it is booming.  I'm talking 10 knots lift!  Interestingly, the Avenal TIP is more accurate for Panoche and Hernandez, where the max altitudes are usually much higher than over Avenal itself, which works great for XC planning out of Hollister.  Empirically I found that the mountains (especially Panoche and Hernandez) gets the TIP=0 and Avenal gets the TIP=-4 at best.  Makes sense to me...     The only unknown is if this is also true for the whole summer.  Last summer and this summer as well I will be flying at Minden, so unless someone from Hollister will be willing to take a high tow and glide to Panoche, we will never know.  Hollister is known for poor soaring conditions most of the summer, but Panoche and Hernandez may be still booming.  Hopefully someone will try it out.
DrJack sez:  Makes sense to me too.  Thanks to Ramy for sharing his extensive experience in the region SE of Hollister.  Avenal users might want to compare this to their experiences in the mountains west of Avenal.

WILLIAMS  Milt Hare  Feb 12, 2002
After using them during the last year, I feel that TIP and BLIPMAP are normally the best forecasts that are available - though the "mountain" Williams TIP has problems in some weather conditions and the "valley" Williams TIP has difficulties with the summer valley inversion.  We are working on the types of weather systems that cause problems, but generally speaking the predictions have been good.  They have alerted me to many great days when I wouldn't normally have spent the time to do a proper forecast.
During the winter, I think the "valley" Williams TIP is probably more accurate than the "mountain" Williams TIP, since the calculation we're using was 'tuned' during the summer conditions and is based on Marysville, which is a long ways from Goat Mountain (we do that so we get a reliable surface temperature prediction since we haven't found one actually in mountains).  Normally, if the "mountain" Williams TIP prediction is unusually high (like 12,000-14,000 feet in January) you should check it against BLIPMAP, or use some other source to verify it.  You can also look at the TIP's lapse rate section to evaluate the airmass stability.
DrJack sez:  For those unfamiliar with the two Williams TIPs, the regular or "valley" Williams TIP is intended to represent conditions in the Central Valley, where the gliderport is located, whereas the "mountain" or MTwilliams TIP is intended to represent conditions in the higher terrain northwest of the gliderport.

WILLIAMS  Milt Hare  March 22, 2002
Read Milt's posting to rec.aviation.soaring to learn about his experience using TIP and BLIPMAP to forecast soaring conditions at Williams over the last year.


Descriptions of your TIP usage based upon your flight experience which will be useful to other pilots can be sent to the page maintainer, Jack Glendening for posting.  Please remember that the purpose of these postings is to help other pilots utilize the TIP forecasts for their own flying, not for you to simply describe a great flight you had since other forums exist for that purpose.  Distillations of experience gained over many flights are especially solicited, but individual flights which illustrate TIP usage can also be posted.  Please consider how your posting can be most useful to others: give specific locations (particularly whether over flat or mountainous terrain), any cloud influence, and whether the flight altitudes reached correspond to the TI=-4 or TI=0 or other TI height (preferably using the TIP's post-analysis).  And, of course, give the site you are flying out of.

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