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Thread: sun feb 9?

  1. #1
    Join Date
    Aug 2014
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    sun feb 9?

    from forecast discussion

    Next weather feature of note will be a dry cold front timed to
    arrive late Saturday nigh into Sunday. By late in the day Saturday
    some onshore breezes will return with a few degrees of cooling
    compared to Friday. Main impacts of the cold front will occur
    Sunday morning with some puffs of wind and cooler temps aloft. The
    surface front and associated pressure gradients dont look too
    strong and not nearly as organized as last weekends frontal
    passage. Most of the energy will be aloft with a cold pool keeping
    the hills chilly and allowing for some afternoon cumulus build ups
    Sunday afternoon.

  2. #2
    Join Date
    Jan 2011
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    575

    Re: sun feb 9?

    Latest rasp and skysight does not show post frontal clouds but showing a great NE wave on Sunday. We need to hear from Kempton...

    Ramy

  3. #3
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    Re: sun feb 9?

    Wow. Saturday now looks like a decent valley day, with 5 thermals. And then a dynamite NE wave on Sunday. Kempton, Kempton, where art thou Kempton to tell us how great it will be and where to go?
    John BB

  4. #4
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    Re: sun feb 9?

    Yes, I've been tracking this setup for a week now, and it's coming in nicely. This morning's charts from Skysight, Norcal and WSC RASPs show improvement, mostly due to the better placement of the cutoff low center causing the 500mb Wind direction to be a bit more E, aligning better with the lower level flows. This is a better trend than the other way, like Dec 30! Ideal center for the cutoff low is S of LA and W of San Diego, and thats where it’ll be early Mon morn, so close enough for our Sun flight.
    Click image for larger version. 

Name:	boxwmax.curr.1000lst.d2.png Feb09 St Helena.png 
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ID:	556710a PST St Helena cross section, notice how the wave goes almost to the ground!

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ID:	5569 10a 850mb Click image for larger version. 

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    An inconsistency tho, is the 500mb Skysight and Norcal RASP are 80-85kt @ 500mb morning, weakening to 60-70kts by end of day vs. the WSC RASP showing 80kts all day. Overall it is a strong day. The extreme N end is weak, so expectations are for no further N than Hyampon. I attribute this to the weakening strength along with less alignment btwn 850mb and 500mb layers. I plan to fly to at least halfway btwn Hyampon and Hoopa tho.

    The south end, Napa Valley from St Helena to Napa airport looks to work nicely given the strong ridgeline wind orthogonal to the ridge. Other oddities are the Williams RASP shows some cu in the Yolla area, not sure why that is, but it does hint there may be some markers.

    Given the above, the WSC task is now:
    108sm Goat- Hyampom H47
    180sm H47 - Napa KAPC
    180sm KAPC - H47
    160sm H47 - WattsWoodland O41
    37sm O41- CN12 WSC
    665sm total, 10.5 hr sun. If you get more ambitious, 1100km=685 sm

    The WattsWoodland leg is so we're closer to WSC in a cross wind fashion as otherwise going directly from St. Helena, which is what I was thinking earlier, is directly into a strong wind late in the day, so a bit risky, even from 18k in FNX to cover that 44sm final glide.

    Always the biggest catch are ground winds at dawn. So far, Windy shows 19 kts at 7a Sunday, so that's right on the edge for the hangar doors. Regardless, I plan to fly with Danny. More as we get closer.
    Last edited by Kempton; 02-07-2020 at 07:50 PM.
    Kemp
    ASH-25 (FNX)

  5. #5
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    Re: sun feb 9?

    And for the record, the NAM charts for Sunday 10a and 4p:

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ID:	5570 10a 850mb Click image for larger version. 

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ID:	5571 4p 850mb

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ID:	5572 10a 700mb Click image for larger version. 

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ID:	5573 4p 700mb

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ID:	5574 10a 500mb Click image for larger version. 

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ID:	5575 4p 500mb

    Let's hope the forecast holds and we're not blown out Sunday morning!
    Kemp
    ASH-25 (FNX)

  6. #6
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    Re: sun feb 9?

    As of this evening, we have myself with Danny as copilot, Thomas, John Cochrane, and Matt Gillis to fly the wave tomorrow. FNX will launch first with FH right after. The scene in the shop:
    Click image for larger version. 

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    Kemp
    ASH-25 (FNX)

  7. #7
    Join Date
    Jan 2011
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    597

    Re: sun feb 9?

    Conditions at first launch winds out of the NWN at 20mph with 33mph gust earlier.
    7:30 FNX with Kempton and Danny launched "5H"
    7:33 FH Thomas launched "FH"
    Pending A5 Matt
    Pending BB John

    Track them on OGN http://glidertracker.org/

    Click image for larger version. 

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    Updates

    8:00 FNX & FH contacted wave near Gt Mountain both in 10-12 kt lift climbing through 12,500'

  8. #8
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    Re: sun feb 9?

    With the exceptional generosity by Rex and Noelle, we were able to put John's ship in the main hangar, with FH and FNX into Danny's shop, greatly aided by Rex’s Cobra wheel dolly:
    Click image for larger version. 

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    Given the experience of last October's 50+mph winds, we couldn't take any chances. Matt Gillis rigged last, and being the smallest at 15 meters, he tied down on the downwind side of the main hangar, with my strong recommendation to tie the wingtip to the dumpster...

    Up before dawn, it's blowing a good 25-30 mph, right at the limit for opening the hangar doors. With all hands on deck from the Mayes family and pilots, we got the tow planes and gliders out without incident. Danny and I launched first at 7:30a, with Thomas right behind us. The Goat wave saw peaks of 11kts after we figured out we were too far upwind:
    https://drive.google.com/open?id=1X4...awAnmFYz7y89ko

    Working our way around Snow, I felt it more conservative to work the Hull wave, then go N to abeam Black Butte, and cross there. Given the 85kt or more wind, the sight picture of what we could achieve going upwind was pretty steep. Hull wave:
    https://drive.google.com/open?id=1EC...tBsXBGeq1SV3Rp

    This was to be the first of several “death dives” to go upwind only 5-10nm, losing 5-10k ft each time with short bouts of 12-20kt sink. Thomas went direct from Snow to Black Butte and lost little. Now moving N paralleling the Black Butte-Anthony- Yolla Wilderness ridgeline, we arrive in the Yolla wave and indeed it was strong. Eyeballing Ruth, it didn’t look that far away, but knowing the strong wind, it was a commitment to get there. Meaning if we go and don’t find the wave, we’ll be stuck too low to return to the Yolla wave. We went downwind to the Island Mt and North Fork wave waypoints, but found nothing. I should have tried the T15 wave, but instead decided to head south as we were losing XC speed. Back to Goat directly with a quartering tailwind, we take a small climb with Thomas in FH:
    Click image for larger version. 

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    then over Clear Lake to confirm the forecast wave. It’s there and we’ll need it on the way back:
    https://drive.google.com/open?id=1uJ...krVxgeetLFYweQ

    Over to St. Helena for a strong climb, then start probing south along the forecast strong Napa valley wave, but don't find anything. Probe downwind, nothing, so we go back to St. Helena to climb again and consider next steps. For max distance we needed the legs south of St. Helena to Napa airport, and the leg N from Yolla to Hyampom. Both are not working, so we’re limited to btwn St. Helena and Yolla. Further, with this wind, it’s too far to go directly to Goat from St. Helena, so we follow H-101 up to Cloverdale, knowing this worked for Ramy back in similar WX in Nov. 2013.

    It’s slow going, but at least we’re going, a mile or so downwind of 101 up to Cloverdale where the wave ends, then death dive across Lampson to over Clear Lake. From 16k we drop to 6k in less than 10 minutes, complete with 16kt sink and Sierra class turbulence as the lake fills our peripheral view. Not advisable unless you had to, as Thomas and Matt did after us. Thomas saw 20+kt sink, erk! Fortunately, the strong lift was there:
    https://drive.google.com/open?id=1Zj...2V6rKIpLMACZD3

    John was behind us in the Goat wave and chose to pass on our drama, hmmmmm…...

    We rocket back up to 17k, move to Goat, and decide we’ve had enough. Back to WSC for an uneventful landing, behind John.

    John’s landing
    https://drive.google.com/open?id=1h6...37JQ43G5G30SLb

    FNX landing
    https://drive.google.com/open?id=1by...TWf7xApXs1SdfU

    Thomas’ landing
    https://drive.google.com/open?id=1VL...b6u_QZsi-VhIIq

    Matt’s landing
    https://drive.google.com/open?id=1VF...gGSdP_10vVd64n

    Videos courtesy of Noelle.

    All in all an interesting day. This is the 2nd day I’ve flown where the winds at 18k are 85-90kts (last one was in the Sierra's in 2003). Given Ramy’s experience last Oct in 90kt winds at 18k, in all three cases, wave didn’t work well at most of the places we expected it to, and only behind the tallest obstacles. Given this, and the greatly diminished XC range and speed, I see the optimum 18k wind speed as 55-60kts as this gives plenty of energy, is proven to trigger wave at the expected spots, but with greatly reduced impact on XC speed. This is true for the Sierra or WSC wave XC.

    Many thanks to Rex, Noelle, Nick, Pablo, for great pre & post flight support, and to Thomas, John and Matt for completing the squadron.

    OLC:
    https://www.onlinecontest.org/olc-3....l?dsId=7689572
    Kemp
    ASH-25 (FNX)

  9. #9
    Join Date
    May 2018
    Location
    San Carlos
    Posts
    44

    Re: sun feb 9?

    Kemp,

    Thanks for sharing your journey. Seeing ambitious goals planned and achieved is wonderful and motivational.

    Dan

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