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Thread: Mon/Tue Dec 29/30 wave watch

  1. #1
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    Mon/Tue Dec 29/30 wave watch

    As of this morning, Dec 22, this season's first Doug Armstrong "backside slider low" is shaping up for Mon/Tue of next week. This is the Tue 4a forecast:
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    500mb....................... 700mb....................... 850mb

    All nice directions and velocities. This pattern originally showed up at 13-16 days, then disappeared and reappeared as of last night. A bit far out to state publicly, but what with Christmas, we need a bit more forward planning space. Will keep watch for a beach mission...

    Btw, this must be a forum record, 9 days without a post...time to get thinking about the new season!
    Last edited by Kempton; 12-24-2014 at 10:52 AM.
    Kemp
    ASH-25 (FNX)

  2. #2
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    Re: Mon/Tue Dec 29/30 wave watch

    Quote Originally Posted by Kempton View Post
    As of this morning, this season's first Doug Armstrong "backside slider low" is shaping up for Mon/Tue of next week. This is the Tue 4a forecast:
    Name:  500mb_192hr_Dec30morn.png
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Views: 478
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    500mb....................... 700mb....................... 850mb

    All nice directions and velocities. This pattern originally showed up at 13-16 days, then disappeared and reappeared as of last night. A bit far out to state publicly, but what with Christmas, we need a bit more forward planning space. Will keep watch for a beach mission...

    Btw, this must be a forum record, 9 days without a post...time to get thinking about the new season!
    Kemp ~ Thanks for the heads up! I have been hoping for a weather change with a little soaring for early in the new year. Staying tuned...
    Pete Alexander -- 98

  3. #3
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    Re: Mon/Tue Dec 29/30 wave watch

    As of Dec 24 morning, the forecast still holds. The offshore flow just about disappeared again on Dec 23's morning forecast, but reappeared today. Of course, as we get closer, the "Cone of Uncertainty" narrows, so here we are, 5-6 days out from the Mon/Tue time period, looking steady.

    Task wise, as this is a very rare event, the only other reference is last year's Nov offshore flow:
    https://www.williamssoaring.com/news/...89-Friday-Wave

    with that period's charts:
    https://www.williamssoaring.com/news/...-%28Thu-Fri%29

    The key difference, looking at the above link vs. the current situation, is that last Nov. the 850, 700 and 500mb were all exactly aligned. In Mon/Tue's case the 850 and the 500mb levels are almost 30 degrees different:

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    Monday afternoon 500mb............... 700mb................ 850mb

    and Tue afternoon:
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    500mb....................... 700mb....................... 850mb

    This may reduce the wave energy propagated upwards to some degree.

    If this forecast holds as of Friday morning, then I'll likely commit to a flight, with co-pilot Jim Darke.

    Now, in the realm of fantasy flight, (Ramy?), based on last Nov's flight, it may well be wave in the lee of the Coast range, just inland of the coast, all the way up to near Eureka. So the task could be: Goat > San Hedrin > Laytonville then parallel the range up to N of Garberville > St. Helena > Diablo > St. Helena > WSC. Think early starts!
    Kemp
    ASH-25 (FNX)

  4. #4
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    Re: Mon/Tue Dec 29/30 wave watch

    I bet it is waving today as we speak....
    problem for me is that my only flying plans is on New Years weekend at Santa Ynez for now since we planning to do a trip south. Hope the offshore will continue into next weekend?

    Ramy

  5. #5
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    Re: Mon/Tue Dec 29/30 wave watch

    Ramy,
    For the New Years weekend at Santa Ynez, it looks like a quiet weekend. BTW, the first working week of January looks like a lot of rain for NorCal.
    Kemp
    ASH-25 (FNX)

  6. #6
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    Re: Mon/Tue Dec 29/30 wave watch

    As of Dec 26 morning, the forecast "sweet spot" is slowly pushing out. Right now it appears all day Tue & all day Wed is a NE flow. A single graphic comparing last year's Nov 22 and the Tue/Wed forecast:
    Click image for larger version. 

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    shows the more northerly flows compared to Nov 22 2013's charts. Differences between Tue & Wed include:
    - Tue 500mb winds are 60-70 knots vs. Wed 40-45 knots
    - Tue 850mb winds are 30-35 knots vs. Wed 20-30 knots
    - Tue wind direction (850-500mb) is 060-020 vs. Wed 030-010

    Still very unusual to have this occur at all. This should allow for a run out to the Pacific and possibly parallel to the coast towards Garberville.
    Last edited by Kempton; 12-26-2014 at 03:29 PM.
    Kemp
    ASH-25 (FNX)

  7. #7
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    Re: Mon/Tue Dec 29/30 wave watch

    With the Dec 28 charts, we see:
    Name:  500mb_060hr_Dec30eve.png
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    500mb....................... 700mb....................... 850mb

    yet the RASP shows:
    Click image for larger version. 

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ID:	2119 . . Click image for larger version. 

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    500mb.............. . . ....... 700mb.. . . . . . ................ 850mb

    So why is there very little to no wave?

    The best answer I can give is that I've seen this before in Sierra wave. When the core of the jet stream is close or on top of the ridge line, it's like water from a nozzle on a hose. There is no waviness because the velocity and energy are dominant and overpower the natural undulation. Like a "rod" of water. This also appeared on the Sierra when the wind speed at 500mb/18,000ft is above 80 knots. So I am "standing down" on a wave flight attempt on Tue.

    Experience on the Sierra is also when the winds are >80 knots, you lose so much of your forward velocity crabbing into the wind, that it's not worth it.

    So like may things in life, it's a bell curve. This only reinforces that wind speeds above 80 knots suppresses wave. More like 50 knots is best at 18K.

    I can't fly Wed, but will watch the RASP. I'll bet it shows wave at the slower 18K speed of 50 knots or so.
    Last edited by Kempton; 12-28-2014 at 08:31 PM.
    Kemp
    ASH-25 (FNX)

  8. #8
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    Re: Mon/Tue Dec 29/30 wave watch

    Kemp,

    I agree with your thinking about too much wind to allow the airmass to bounce and create wave.

    I had a feeling from your first post and analysis that Tuesday would have too much wind for a good wave day.
    Pete Alexander -- 98

  9. #9
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    Re: Mon/Tue Dec 29/30 wave watch

    This morning's RASP wave charts indeed show a strong classic setup on the Goat/Snow range and other places:
    Click image for larger version. 

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    500mb 10am . . . . . . . . . . . . 5p

    Click image for larger version. 

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    700mb 10am . . . . . . . . . . . . 5p

    Click image for larger version. 

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    850mb 10am . . . . . . . . . . . . 5p

    With luck we'll have more N wind days this season, but for this one, it'll be a dry lab!
    Kemp
    ASH-25 (FNX)

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