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Thread: Thermal Watch: Sat/Sun May 4-5

  1. #1
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    Thermal Watch: Sat/Sun May 4-5

    As of this morning's charts, we could have a unusually good day on Sunday, with a low offshore, heating from the desert, and a shot of moisture from the East:
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    This could produce our first day this season to go to the OR border. Note how it's hotter in southern Oregon than in the Central Valley!

    Keep watching.....
    Kemp
    ASH-25 (FNX)

  2. #2
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    Re: Thermal Watch: Sat/Sun May 4-5

    Quote Originally Posted by Kempton View Post
    As of this morning's charts, we could have a unusually good day on Sunday, with a low offshore, heating from the desert, and a shot of moisture from the East:
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    This could produce our first day this season to go to the OR border. Note how it's hotter in southern Oregon than in the Central Valley!

    Keep watching.....
    Good training material Kempton, and I agree it does look promising for Sunday. I have had a couple of (as in two) pilots tell me (within the past 10 days) to keep posting charts such as this because they do in fact appreciate the posting and the ensuing discussion surrounding the charts. They really appreciate the discussion. I tend to be overly specific, and tend to lose people, where as you Kemp, present the bottom line, and that is appreciated more so by more people.

    As for these charts, let me discuss them as if I had posted them....

    Chart 1 is 700 mb - that is 10,000 ft, white with light green bands of light moisture at that level. it is a fcst for 12 Z on 5/8, which is Monday at 5 AM.
    light moisture over L.A. coastline, dry elsewhere, winds over WSC 10 to 15 kts from the south. Probably bringing in warm air dry at 10,000 ft to our area on Monday AM. If we are going to look closely at Sunday, it might be good to look at the chart for 12 hours earlier, but I don't have that one. But Monday looks promising as well, based on this chart - just a bit dry.

    Chart 2 is multicolored, showing fcst pressure (level of the constant pressure really) and temps at 5,000 ft ( 850 MB), and this is for 00z Monday , which is Sunday at 5 PM. It shows it to be iso thermal (all the same temp color band) from slightly east of Tahoe to Eugene Oregon, and cooler to the SW of that line. As Kemp pointed out, it is fcst to be warmer in Oregon than over Sacto Vly. I might also point out that it shows a mild ridge extending from LA to Sacramento, giving us light winds at 5,000 from Yolla to Shasta.

    Chart 3 is relative humidity (RH) ( using colors) and showalter index (using lines). This too is for 00z on Monday , which is 5 PM Local on Sunday. Nice patch of unstable air over NE corner of California. Expect CAPE to be high, possible OD if moisture increases, but for now it is only 50 % RH. When Show gets to zero (the heavy white line) they put the hash marks over that area it to get your attention.

    I agree with Kemp on all counts. Let's keep watching.

    The calendar certainly tells us we are within the zone of having a really good day. All of my best long flights have been in May as well.


    I hope this extra discussion has been helpful - to those that are interested.
    Peter Kelly

  3. #3
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    Re: Thermal Watch: Sat/Sun May 4-5

    As one who is admittedly deficient in weather chart reading and prognosticating ability, I value both the 'executive summary' approach by Kemp and the somewhat more tutorial interpretation by Peter. I hope you both keep up the good work. Still looks like reading tea leaves to me, but I appreciate the effort both of you put into explaining the data and starting the discussion. The CAL model (the only one I am truly capable of reading) supports this weekend as well. Count me in.
    Jim D. - 1B

  4. #4
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    Re: Thermal Watch: Sat/Sun May 4-5

    I looked at all the unisys charts just now.
    As that low comes over the top of us (moving from west to east) it sure does bring a lot of moisture to us on Monday.
    Peter Kelly

  5. #5
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    Re: Thermal Watch: Sat/Sun May 4-5

    Hey!
    is everyone watching the charts?
    That trof aloft that I saw this morning (we are still talking about sunday at 5 PM) has now morphed into a closed low. wow!

    On the vsa wx page see the link...
    under
    Forecast Chart Models -


    see the 3rd line...
    GFS/Avn Model - 5 day fcst, in 12 hr lots, updated 2x at 11 PST

    look at the 3.5 day models for sfc, 5k, 10 k, 18k, and RH.

    here they are...

    first is 500 mb - 18k...
    closed low, bringing in moisture aloftcool winds from the sw/ swirling around that low.

    next is 700 mb --- 10 k...
    low is wider, covers more miles, pockets of instability indicated by multicolored dots on the thrird ring - central vly, along the CA/NV border in the sierras. flow is from the SSW pretty tight pressure gradient- so wind at 10 k is probably 15 to 20 kts.

    next is 850 mb --- 5k---
    low off the coast - see red east side of NE CA. See the small low aroungd that area. see slight ridge south to north up the central valley - all of this is at the 5k level. still yellow - cooler air in the central valley

    next is Sfc Precip. and the thickness from sfc to 18k ( 1000 - 500 mb)
    see ridge along the coast - bay area to eureka. see the low off the coast and low over the sierras.

    last is the RH/Show
    very pink - dry bay area to hayfork - 30 % RH. See the hashed patch is still over NE CA, and mositure is inside of that area of instability of 50 % RH.


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    Bottom line?

    What do you think Kempton?

    based on the above fcsts... to me... it still looks good for sunday, but it'll be blue getting up to the trinity's. but nice clouds over to Klamath Falls.

    You really gotta expand the charts to see all of that, and of course you need a good imagination, and have a high wanna fly factor or as mentioned/ defined a few days ago the EF (Enthusiasm Factor).

    I hope this helps, my feedback loop has shown an increased number of pilots watching charts - up from 3 to a total of 5, just in the past 24 hrs.

    Yikes... settle down people.. as Pete 98 likes to say - it's only a forecast!

    What you see is what you get...

    As 7V might say - just fly what you get....
    Last edited by Peter Kelly; 05-02-2013 at 08:48 AM.
    Peter Kelly

  6. #6
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    Re: Thermal Watch: Sat/Sun May 4-5

    With all the TV news about fires, and smelling smoke all night long in Vaca, I thought I'd check images and reports.
    I came up empty handed on the Tehama/ Butte county line fire (the closest one affecting the Mendos), the one up near Quincy, etc.
    No recent TFR's or Forest Service posting and all FS sat images are old.
    All of my pages are old, but you'll want to recheck all of that before we fly again.
    Peter Kelly

  7. #7
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    Re: Thermal Watch: Sat/Sun May 4-5

    Peter said "Yikes... settle down people.. as Pete 98 likes to say - it's only a forecast!"

    Hmm, to some degree, getting people excited IS part of the experience. Now i'm not a therapist, but I am a *sales guy*, so as the saying goes, enough knowledge to be dangerous!

    Now the Pete Alexander side of me says "excitement only to the extent that it doesn't cloud you judgement..." 8^)

    Onto the weather. I'm sitting in Bob Ireland's house (thanks Bob!) doing work as I part time chaperone Wes' field trip that happens to be only 8 miles away! So I drove up yesterday through the smoke of the Cedar Fire, on the SW side of Lassen park. Really bad smoke in the valley, 1 mile visibility! Currently 55 acres and 40% contained.

    Saturday from the BLIPS looks good:
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    and Sunday is looking good from the moisture standpoint to go to the OR border:
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    with good heating:
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    Kemp
    ASH-25 (FNX)

  8. #8
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    Re: Thermal Watch: Sat/Sun May 4-5

    Although this thread is entitled "Thermal Watch" let's keep pressing on and keep looking at the bigger flying picture.

    Friday AM update:

    Now that we have a RASP for two days out (thank you Andy H.), we can compare apples to apples.

    We sure are going to have a wind shift. (Hmmm, must have been a frontal passage). That trof aloft - that was in the fcst last Monday and Tuesday is now a full blown low - with all the accompanying cyclonic winds... (there is an emphasis on "blown" in full blown low.)

    BL winds Sat vs Sunday
    Yolla Peak Avg =

    Sat. NNE/about 18 kts and Sun. ESE/ about 18 kts

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    As for surface winds on each day at WSC, it doesn't look like much fun on Saturday - wrestling with the north wind during assembly... but Sunday sure looks good...

    Sat @ 10 AM N/15 and decreasing a bit later on, Sun sfc wind is less than 8 kts from E.

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    And finally, the big thing we want to focus on - how high can you go????

    Sat looks good, but Sunday is even better....

    Yolla Peak

    Sat = 10 k Sunday = 11k bordering on 14... another holy cow...

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    I'll take a tow on Sunday for sure.
    Last edited by Peter Kelly; 05-03-2013 at 09:48 AM.
    Peter Kelly

  9. #9
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    Re: Thermal Watch: Sat/Sun May 4-5

    Interesting, as the NAM blipmap is showing mediocre conditions with lift to only 9K over the mendos and no clouds unless you go way west of Yolla where there is a small area where the lift is predicted to go to 13K. This looks unrealistic to me so will be interesting to see how Sunday will turn out, but I certainly dont see conditions to go to Oregon.

    Ramy

  10. #10
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    Re: Thermal Watch: Sat/Sun May 4-5

    I have to agree with Ramy at this point. I'm not very good with the charts Peter and Kempton use so I rely on RASP/BLIP. From what I see there, Hcrit and even bl top don't look like anything special. The b/s ratio is _very_ low (worse so in the mountains) and the surface and bl wind appears to be s/s-e with no opposing wind even shown on the RASP map (i.e., no apparent convergence to help things - as confirmation the convergence map shows basically nothing, certainly nothing organized/consistent). Maybe there will be good ridge soaring on the eastern edge of the Mendocinos? :-) Oh, and it's going to be mostly/completely blue unless you get fairly far west (basically out of our typical area). It almost seems like the conditions are the reverse of the usual afternoon sea breeze coming into the mountains from the w/n-w, squeegee-ing and killing any lift in its path as it progresses.

    Looking at the NWS forecast discussion it sounds like it all depends on the timing of the westward moving low. If it's in the wrong spot on the wrong day (using the calendar model for those of us not retired), then it'll be a bummer. Mid-next week might be good after the front passes to the east again.

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