End of November 2017

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End of November 2017

Postby sd » Mon Nov 27, 2017 11:25 am

Monday morning forecast the end of November workweek…

Wednesday looks stellar…
Confidence in the progression is high, but not so much in the timing. It is just a forecast, so what is delivered won’t be exactly what was ordered. The models were calling for 70% chance of rain last night, but it was dry. The satellite loop did show a narrow band of cold front rain speeding through, but somehow Carpinteria was between the drops?

I’ll ramble a bit because no rush today. Too much wind except for possibly some diehard hang gliders? I did launch from the North Side Alternator when it was gusting to 40 once… got to 8K on the front range, tanked up over Red Mountain and The Avenue in Ventura to land just short of Point Mugu runway 27, backing up in a 35-mph wind (threw the anchor because I was too low to cross the airbase).
On Monday the lapse rate is ballistic below a sharp inversion about 5K, but the north wind is too much. Bates might work for fast hang gliders…??

https://www.youtube.com/watch?v=BXgvrx5wpE8
https://www.youtube.com/watch?v=vBgGP9Wh3Lk

On Tuesday, both the wind and the lapse rate back down and it looks flyable in SB.
On Wednesday, the lapse rate cranks back up into the ballistic range with the lift going high, like 8 or 9K below a sharp inversion cap.

There are often reasons for launching from Ojai compared to SB, but SB offers simpler logistics. The reasons for launching from Ojai are either a better lapse rate, or downwind potential toward SB, or both. It should be noted that the Ojai Ranger District typically closes the Nordhoff Ridge road for the season on December 15th, so you only have a couple more weeks to drive up. We will use the Nuthouse when the road is closed, but the hike is robust.

On Tuesday, Ojai offers a better lapse rate than SB, up to about 5K. SB’s lapse rate is weaker, but not inverted. The wind backs off enough that I suspect SB will work good enough that it isn’t worth the cost of trekking to Ojai

Wednesday is a day to call in sick at work (but the timing could vary?). The lapse rate and max altitude look impressive in both SB and Ojai, but Ojai offers better downwind potential. The wind in SB starts out light from the ESE down low (but still stiff from the NW above the inversion), then the strong lapse rate pulls to draw light from the west down low but clocking around to come from the NNE up above 5 or 6K, with increasing wind with increasing altitude. The wind at the top of the lift (about 9K) is in the low-teens mid-day, and mid to upper teens around 8K late in the day.

With stellar altitude potential in SB on Wednesday, no need to go to Ojai for altitude, but Ojai offers better downwind XC potential. You can likely do laps in SB by going west early, then turning to run eastbound low when the low-level west pulls in. The trick to making progress eastbound in the afternoon is to stay as low as you dare. There will be more wind from the east up higher. You want to think like a hot-air-balloon pilot.

Flying from Ojai on Wednesday, the strategy is the opposite. You want to stay as high as you can to maximize the tail wind form the east and stay above the lower level flow from the west. Top of the lift in Ojai is a little higher than SB, but not much. The low-level flow is from the east all day, so you will eventually hit a dead end at all altitudes plugging eastbound. Early there is some wind from the SW near the top of the lift, but that clocks around to come from the east NE in the afternoon. The afternoon wind is more from the east down low and more from the NE to north with increasing altitude. The midday wind is mid-single digits, even close to the top of the lift, then later in the day it builds into the low to upper teens above 6K, increasing with altitude.

There might be some over-the back-potential, but I didn’t take a look because I couldn’t budget the time.

My recommendation on Wednesday is to launch from Ojai early. You can likely get off from Chiefs early, but with building wind from the east, Nordhoff might be a better call. If the east wind isn’t too much, you might plug upwind toward the higher terrain, and if you are early enough it might initially be downwind at the higher altitudes going eastbound toward the Topa Bluffs? The altitude should be good enough that going downwind to SB will be easy, even for rookie pilots, but the lift is strong, so you should have some bump tolerance. I recommend an early launch because is maximizes the day, but also, the wind is lighter early, so you might be able to tag an east end turn point that is further east compared to later in the day? Stay as high as possible to reach a west end turn point, then come back low toward Carpinteria with the onshore tailwind (under the higher altitude east wind). Going over Casitas Pass eastbound late in the day might be problematic because you would need to climb up into a headwind… but you will likely run out of clock at the end of the day anyway, so… Nordhoff to the Topa Bluffs to as far as you can reach westbound and back to Bates?

On Thursday, the Santa Anna flow seems to be backing off? The lapse rate backs off also, but is still marginally okish in SB and good in Ojai. Ojai has less wind than SB on Thursday, so again, Ojai looks like a better call from a lapse rate/altitude perspective, but not necessarily from an XC perspective. The wind in SB is light from the west down low, then mid-teens from the north up higher. If you can get past Castle Ridge, you can likely get into the Ojai Valley from a SB launch. The low level base wind in Ojai is very light down low and the same as SB up higher (low to mid-teens from the north), but the lapse rate is much better, so the afternoon flying in Ojai looks good. Top of the lift in Ojai is maybe 6K, and significantly lower in SB.

The current forecast is for the Santa Anna event to be short followed by potential rain this coming weekend. I’ll be in Chicago this coming weekend, so someone local will have a better perception of the local progression and be able to offer a more accurate weekend forecast.
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Tuesday forecast for Wednesday

Postby sd » Tue Nov 28, 2017 10:47 pm

Monday’s forecast for Wednesday left me salivating, but the models re-evaluated on Tuesday to lower expectations. The lift still looks ok, but only to 6K instead of 8 or 9, and a substantially weaker lapse rate in Santa Barbara. Would still recommend launching from Ojai, but it will be a little more challenging to stay above the lower level onshore flow from the west on the westbound leg. SB should work also, but not as robust as Ojai, and it might be hard to get over Casitas pass against a headwind at the altitudes needed to get over the higher terrain?

The attached NAM model Skew-T forecast soundings for midday Wednesday show a distinct change between the Monday and Tuesday forecast for Wednesday. Monday’s forecast for Wednesday was calling for much colder air aloft. Monday’s forecast discussion was expecting a small-scale low to wobble overhead on it’s way offshore, but by Tuesday the “wobble” seems to have either missed us or dissipated? The winds are a notch lower, which should be good. The addition of high clouds is a mixed bag. They will diminish the heating and resultant lift, but the heating might also be more diffused resulting in fewer bumps?

Still looks like a good day to fly, but the task of Ojai to the Bluffs to SB and back to Carp is now looking overly optimistic.

For the readers new to skew-t graphs, the red line is the temperature profile. How much the red line leans left corelates to how strong the lapse rate is. If the dew point and temperature meet, then you will have condensation (clouds). The wind is shown on the right, with the barbed end pointing into the direction the wind is coming from. More barbs mean more wind. You also might want to read John Scott's notes at: http://scpa.info/weather/info/model.htm

The basic scenario is a mild Santa Anna event that is fading, so there is a little less east wind each day. The best lapse rate still looks like Wednesday.
Attachments
nam_2017_11-27_12z_for_ojai_29_21z.png
Monday's Ojai Forecast NAM Skew-T for Wednesday
nam_2017_11-27_12z_for_sb_29_21z.png
Monday's SB Forecast NAM Skew-T for Wednesday
nam_2017_11-28_18z_for_ojai_29_21z.png
Tuesday's Ojai Forecast NAM Skew-T for Wednesday
nam_2017_11-28_18z_for_sb_29_21z.png
Tuesday's SB Forecast NAM Skew-T for Wednesday
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