monday wowsers

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monday wowsers

Postby Aaron » Wed Jun 12, 2013 8:37 pm

little john gave me a call monday morning and said clouds were popping and he couldnt find anyone to go flying with. la cumbre was 13 degrees cooler then monticito by noon and it didnt dissappoint. climbed to 3700 right off skyport and there were solid 800fpm up climbs all over the place. touched the clouds a few times at 4000, john hit 4400 at cathedral once as he tagged no name and back. east wind down low/west up high i got rejected at ej bowl as the lift seemed to be all out front, even on the front of the front knobs and canyon knobs. it was rowdy for me and i bailed all the excitement after about 40 minutes of attempted scooting around and cruised out over town where lift was everywhere on both sides of the riveria etc. after landing timmay! called saying jeffy was in a fat convergence at the hill. i cruised over, the convergence was gone but timmay! was playing in wild wind having fun getting popped and dropped and up and down all over the place. he eventully hooked a fatty at the point around 3pm and took it over to the wilcox and just squeeked into the windward side of the wilcox for the connection. i drove over and joined him and janthony for an hour long good time of swingin around on the cliff.

my sb weather 2 cents:(feel free to tell me i'm a bonehead and dead wrong if you disagree) sundowner, southside, and bobA all seem really good at predicting amazing days. Little john says he can feel the pressure change in his skin, and hammer is a bad ass and can stay aloft in anything so he goes no matter what as he is a veteran junkie. i have a hard time predicting the weather and enjoy my mini flights in the sb backyard, so i pretty much figure that if it is too windy that will be apparent and therefore only focus on one thing. That is the real time temps/wind of monticito foothills which are at about 1600ft and la cumbre at 3900ft. i have found over the last couple years that if the temp is 7+ degrees cooler at la cumbre then i have a decent chance of staying up high(4000ish), 10+ degrees cooler we are definately getting up and getting around, 13+ degrees cooler and it is crackin. i dont quite understand the discussion but i know when it mentions a cold air mass as it did monday then we get a lapse rate instead of a collapse rate.

If temps are even or hotter at la cumbre then at monticito, then it is often soarable in the marine layer down low, and often on those days it is more buoyant later in the day. i know 13 degrees over 2300 feet isnt that much but it seems to make santa barbara go off. i also look at the pressure at la cumbre on the same chart.(1013 millibars is normal sea level) I find anything under 1020 at la cumbre to be low pressure and if the temps are right, lift will be abundant and all over the place. i find that over 1020 seems high pressure around here which if the temps are right we can get rocket small cores at the usual spots and the glides are easier and smoother because of the stability allowing us to get around better. (the 4 crackin cloud days of memorial day weekend, the pressure all hovered around 1012-1016(i think it got up to 1018 on the fourth day) with 10-11 degree differences) its odd to me that la cumbre rarely says below 1013 at 4000ft and when it does it is often raining. those are just my amateur bonehead observations for having an idea of what i am getting myself into that day. i put it out there, so feel free to tear it apart as i am curious about the whole weather mystery too. i use the wind alert app on my phone and favorite all the santa barbara wind stations so i get a quick glance at any moment. make sure to look at the times as moniticito only posts every hour. the times need to be close to get an accurate temp difference.
Aaron
 
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Lapse Rate

Postby sd » Wed Jun 12, 2013 10:55 pm

Aaron wrote: focus on one thing. That is the real time temps/wind of monticito foothills which are at about 1600ft and la cumbre at 3900ft. i have found over the last couple years that if the temp is 7+ degrees cooler at la cumbre then i have a decent chance of staying up high(4000ish), 10+ degrees cooler we are definately getting up and getting around, 13+ degrees cooler and it is crackin.


Aaron, I think your weather analysis method is effective and mathematically correct.

FYI, the dry adiabatic lapse rate (the temperature change of a raising thermal below Cloudbase) is about 5.38 degrees F per thousand feet, so a 13 degree spread in the atmospheric temperature profile over 2300 feet (Montecito to La Cumbre) is 5.65 degrees F per thousand feet, which is very strong and considered spontaneously unstable.

When referring to the “dry” adiabatic lapse rate, we assume the air temperature is above the dew point. When we reach the dew point (Cloudbase) the physical process of condensation releases energy (latent heat) into the air such that the added heat will reduce the rate of cooling as the rising parcel of air continues to climb. At Cloudbase we refer to the saturated (wet) adiabatic lapse rate, which varies considerable with temperature, so we have more variance. If a lot of moisture is being released, the thermals can accelerate (cloudsuck).

Some rounded numbers at our flying altitudes (the math is not linear so the numbers are not fixed at all altitudes).
*The dry adiabatic lapse rate (cooling rate of a rising and expanding parcel of air / "thermal" (assuming no dilution form edge mixing): 3 Degrees C or about 5 ½ Degrees F per thousand feet.
*The typical lapse rate of the air mass is about 2 degrees C or about 3 ½ degrees F per thousand feet.

The winds aloft forecast list altitude in 3K increments, so as a general rule of thumb, if the temperature spread is more than 6 Degrees C (3K feet x 2 degrees C) then the day is better than average. If the temperature spread is less than 6 degrees, the day is more stable (Pine is good on an average day). The winds aloft forecast does not list temperatures within 3K of the surface, so there is no temperature listed for the 3K Santa Barbara Interpolation, so looking at the temperature spread between the Montecito Reporting Station and La Cumbre Peak is likely the best local indicator for SB on most days. On the higher days, the 6K winds aloft temperature is worth noting. The 6K temperature is more useful for Ojai and Pine because we don’t have a reporting station on those ridge lines like we do in SB.

In reading the weather data, it should be noted that the models are broad based. We only have a couple winds aloft reporting stations within our hundred mile radius (SBA, WJF, and a bit further out BIH and ONT). Surface heating is not homogenous. Thermal “puddles” will be hotter than a reported average. There are local fudge factors. The Ojai report is usually a couple degrees less than the forecasted temperature. Ozena and to a lesser extent Rose Valley don’t report reliable direction because the Ozena station is in a swirl zone. The point being, we can’t rely solely the broad based math. Local variation and fudge factors play a huge part, so we look at a mix of local indicators, sometimes through tinted lenses because it’s Saturday and we want it to be “good”!!

For future reference, I posted your 2 cents at
http://scpa.info/sites/santa_barbara/weather/aaron_2_cents.htm
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Re: monday wowsers

Postby Aaron » Fri Jun 14, 2013 6:19 am

wow! thanks tom for the discussion and weather lesson. much appreciated!

p.s. nice job baggin the topa bluff!

for those of who havent visited tom's site it has a wealth of local information including great local weather explanations. http://paraglide.net/comment/index.htm
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