Soaring Guidance
Issued by NWS Denver/Boulder, CO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

963
UXUS97 KBOU 221227
SRGBOU

Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0627 MDT Friday, September 22, 2017

This forecast is for Friday, September 22, 2017:

If the trigger temperature of 78.5 F/25.9 C is reached...then
   Thermal Soaring Index....................... Excellent
   Maximum rate of lift........................ 829 ft/min (4.2 m/s)
   Maximum height of thermals.................. 14490 ft MSL (9205 ft AGL)

Forecast maximum temperature................... 83.0 F/28.8 C
Time of trigger temperature.................... 1130 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 7945 ft MSL (2659 ft AGL)
Thermal soaring outlook for Saturday 09/23..... Poor

Wave Soaring Index............................. Good
Wave Soaring Index trend (to 1800 MDT)......... Becoming poor after 1200
Height of stable layer (12-18K ft MSL)......... 14901 ft MSL (9616 ft AGL)
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 24023 ft MSL (18738 ft AGL)
Wave soaring outlook for Saturday 09/23........ Poor

Remarks... None

Sunrise/Sunset.................... 06:47:39 / 18:56:26 MDT
Total possible sunshine........... 12 hr 8 min 47 sec (728 min 47 sec)
Altitude of sun at 12:52:03 MDT... 50.21 degrees

Upper air data from rawinsonde observation taken on 09/22/2017 at 0600 MDT

Freezing level.................. 15875 ft MSL (10590 ft AGL)
Convective condensation level... 20546 ft MSL (15261 ft AGL)
Lifted condensation level....... 18099 ft MSL (12814 ft AGL)
Lifted index.................... +2.6
K index......................... -1.1

Height  Temperature  Wind  Wind Spd  Lapse Rate  ConvectionT  Thermal  Lift Rate
ft MSL  deg C deg F   Dir   kt  m/s  C/km F/kft  deg C deg F   Index    fpm  m/s
--------------------------------------------------------------------------------
 50000  -64.1 -83.4   235   73   38  -1.1  -0.6   86.8 188.3    34.0      M    M
 45000  -61.7 -79.1   220   82   42   4.3   2.4   65.8 150.4    23.4      M    M
 40000  -55.2 -67.4   230   75   39   5.2   2.9   53.8 128.8    17.0      M    M
 38000  -51.7 -61.1   230   70   36   5.8   3.2   49.9 121.9    14.8      M    M
 36000  -48.2 -54.8   225   66   34   6.4   3.5   46.9 116.4    13.0      M    M
 34000  -43.4 -46.1   220   60   31   6.8   3.8   44.4 111.9    11.6      M    M
 32000  -37.7 -35.9   215   56   29   9.8   5.4   44.0 111.2    11.7      M    M
 30000  -32.3 -26.1   215   56   29   8.6   4.7   43.6 110.4    11.6      M    M
 29000  -29.7 -21.5   215   56   29   8.6   4.7   42.9 109.3    11.2      M    M
 28000  -27.1 -16.8   210   56   29   8.6   4.7   42.4 108.3    11.0      M    M
 27000  -24.5 -12.1   210   56   29   8.6   4.7   42.0 107.6    10.8      M    M
 26000  -21.9  -7.4   205   57   29   8.6   4.7   41.7 107.1    10.7      M    M
 25000  -20.3  -4.5   205   57   29   2.7   1.5   40.2 104.4     9.6      M    M
 24000  -19.5  -3.1   205   63   32   4.4   2.4   37.6  99.8     7.5      M    M
 23000  -17.9  -0.2   210   59   30   8.1   4.5   36.1  97.0     6.3      M    M
 22000  -15.1   4.8   210   55   28   9.0   4.9   35.9  96.6     6.2      M    M
 21000  -12.4   9.7   215   52   27   9.0   4.9   35.6  96.1     6.1      M    M
 20000   -9.7  14.5   220   48   25   9.0   4.9   35.4  95.8     6.0      M    M
 19500   -8.3  17.1   220   46   24   8.9   4.9   35.3  95.5     5.9      M    M
 19000   -6.9  19.6   220   45   23   8.2   4.5   35.1  95.2     5.8      M    M
 18500   -6.0  21.2   220   44   23   6.6   3.6   34.5  94.1     5.3      M    M
 18000   -4.8  23.4   220   44   23   7.9   4.3   34.2  93.5     5.0      M    M
 17500   -3.6  25.5   215   45   23   8.0   4.4   33.9  93.0     4.8      M    M
 17000   -2.4  27.7   215   45   23   7.9   4.4   33.6  92.5     4.6      M    M
 16500   -0.8  30.6   220   46   23   5.4   2.9   32.9  91.3     4.0      M    M
 16000   -0.0  32.0   220   46   24   5.7   3.1   32.2  90.0     3.4      M    M
 15500    0.8  33.4   225   44   23   6.7   3.7   31.6  88.8     2.7      M    M
 15000    0.8  33.4   225   43   22  -6.5  -3.5   30.0  86.1     1.3      M    M
 14500    0.9  33.6   230   42   22   7.8   4.3   28.6  83.4    -0.1    822  4.2
 14000    2.0  35.6   230   40   21   7.6   4.1   28.2  82.8    -0.5    774  3.9
 13500    3.1  37.6   230   37   19   7.5   4.1   27.8  82.1    -0.8    726  3.7
 13000    4.2  39.6   235   34   18   7.4   4.0   27.5  81.5    -1.2    678  3.4
 12500    5.4  41.7   235   32   16   9.2   5.1   27.2  81.0    -1.4    626  3.2
 12000    6.8  44.2   240   29   15   9.1   5.0   27.2  80.9    -1.5    571  2.9
 11500    8.1  46.6   240   28   14   9.1   5.0   27.0  80.7    -1.7    516  2.6
 11000    9.5  49.1   240   27   14   9.1   5.0   27.0  80.5    -1.8    461  2.3
 10500   10.8  51.4   240   23   12   9.1   5.0   26.8  80.3    -1.9    406  2.1
 10250   11.5  52.7   240   21   11   9.1   5.0   26.8  80.2    -2.0    378  1.9
 10000   12.1  53.8   240   20   10   8.7   4.8   26.7  80.1    -2.1    351  1.8
  9750   12.8  55.0   240   20   10   8.4   4.6   26.6  79.9    -2.2    325  1.7
  9500   13.4  56.1   235   19   10   8.5   4.7   26.5  79.7    -2.3    299  1.5
  9250   14.0  57.2   235   19   10   8.5   4.7   26.4  79.6    -2.4    273  1.4
  9000   14.6  58.3   235   19   10   8.5   4.7   26.3  79.4    -2.5    247  1.3
  8750   15.3  59.5   230   19   10   8.5   4.7   26.2  79.2    -2.6    220  1.1
  8500   15.9  60.6   230   20   10   8.4   4.6   26.1  79.0    -2.7    194  1.0
  8250   16.5  61.7   225   20   11   8.8   4.8   26.0  78.9    -2.9    168  0.9
  8000   17.1  62.8   225   21   11   7.3   4.0   25.9  78.7    -3.0    142  0.7
  7750   17.7  63.9   225   19   10  12.9   7.1   25.8  78.5    -3.1    116  0.6
  7500   18.4  65.1   225   18    9  -7.8  -4.3   25.7  78.3    -3.2     90  0.5
  7250   17.0  62.6   220   16    8  -8.1  -4.4   23.7  74.6    -5.3    122  0.6
  7000   17.7  63.9   220   14    7  13.3   7.3   23.5  74.4    -5.4     96  0.5
  6750   18.3  64.9   225   13    7   5.4   3.0   23.4  74.2    -5.5     70  0.4
  6500   18.4  65.1   230   12    6  -6.7  -3.7   22.8  73.0    -6.2     61  0.3
  6250   17.7  63.9   240   11    6  -1.9  -1.0   21.4  70.5    -7.6     73  0.4
  6000   18.2  64.8   250   10    5   9.3   5.1   21.2  70.1    -7.8     49  0.3
  5750   18.8  65.8   265   10    5   7.4   4.0   21.0  69.7    -8.1     26  0.1
  5500   19.3  66.7   280   11    6   3.9   2.1   20.8  69.4    -8.3      3  0.0

 * * * * * * Numerical weather prediction model forecast data valid * * * * * *

           09/22/2017 at 0900 MDT          |       09/22/2017 at 1200 MDT
                                           |
CAPE...     0.0    LI...       +3.4        | CAPE...    +6.0    LI...       +1.1
CINH...    -0.1    K Index... +15.4        | CINH...    -1.7    K Index... +21.0
                                           |
Height Temperature  Wnd WndSpd  Lapse Rate | Temperature  Wnd WndSpd  Lapse Rate
ft MSL deg C deg F  Dir kt m/s  C/km F/kft | deg C deg F  Dir kt m/s  C/km F/kft
--------------------------------------------------------------------------------
 50000 -63.6 -82.5  220  29 15   1.3   0.7 | -63.4 -82.1  215  31 16   1.7   1.0
 45000 -60.7 -77.3  220  43 22   4.2   2.3 | -60.3 -76.5  220  47 24   3.6   2.0
 40000 -54.4 -65.9  225  45 23   5.0   2.8 | -54.9 -66.8  220  50 26   4.6   2.5
 38000 -50.9 -59.6  225  44 23   5.9   3.3 | -51.2 -60.2  220  49 25   6.3   3.4
 36000 -46.8 -52.2  220  44 22   6.0   3.3 | -46.9 -52.4  220  48 25   6.3   3.4
 34000 -42.6 -44.7  220  41 21   7.6   4.2 | -42.6 -44.7  215  46 24   7.6   4.2
 32000 -38.0 -36.4  220  39 20   7.6   4.2 | -38.0 -36.4  215  43 22   7.6   4.2
 30000 -33.3 -27.9  215  35 18   8.0   4.4 | -33.4 -28.1  210  40 21   7.9   4.3
 29000 -30.9 -23.6  210  34 17   8.0   4.4 | -31.0 -23.8  210  39 20   7.9   4.3
 28000 -28.5 -19.3  205  32 17   8.1   4.4 | -28.6 -19.5  210  37 19   7.9   4.3
 27000 -26.2 -15.2  205  31 16   7.3   4.0 | -26.4 -15.5  210  36 19   7.4   4.1
 26000 -24.0 -11.2  200  31 16   7.4   4.0 | -24.1 -11.4  210  35 18   7.4   4.1
 25000 -21.8  -7.2  200  30 16   7.4   4.0 | -21.9  -7.4  210  34 18   7.4   4.1
 24000 -19.6  -3.3  200  30 15   7.5   4.1 | -19.8  -3.6  210  34 17   6.6   3.6
 23000 -17.4   0.7  200  29 15   7.5   4.1 | -17.8  -0.0  210  33 17   6.6   3.6
 22000 -15.1   4.8  195  28 15   7.5   4.1 | -15.9   3.4  210  32 17   6.6   3.6
 21000 -12.9   8.8  195  28 14   7.3   4.0 | -13.9   7.0  210  31 16   6.8   3.7
 20000 -10.7  12.7  200  27 14   7.3   4.0 | -11.4  11.5  210  30 15   6.8   3.7
 19500  -9.1  15.6  200  27 14   7.3   4.0 | -10.4  13.3  210  30 15   6.8   3.7
 19000  -8.0  17.6  200  26 14   6.8   3.7 |  -9.4  15.1  210  29 15   6.6   3.6
 18500  -7.1  19.2  200  26 13   6.5   3.5 |  -8.5  16.7  210  28 15   6.5   3.6
 18000  -6.1  21.0  205  26 13   6.5   3.6 |  -7.5  18.5  215  27 14   6.6   3.6
 17500  -5.2  22.6  205  25 13   5.8   3.2 |  -6.6  20.1  215  26 14   6.1   3.4
 17000  -4.4  24.1  205  25 13   5.9   3.2 |  -5.7  21.7  215  25 13   6.2   3.4
 16500  -3.5  25.7  210  24 13   5.8   3.2 |  -4.8  23.4  215  24 13   6.5   3.6
 16000  -2.7  27.1  210  24 12   5.8   3.2 |  -3.9  25.0  215  23 12   6.7   3.7
 15500  -1.9  28.6  215  23 12   5.9   3.2 |  -2.9  26.8  220  22 11   6.8   3.7
 15000  -1.0  30.2  215  23 12   6.3   3.5 |  -1.9  28.6  220  21 11   7.1   3.9
 14500  -0.1  31.8  220  22 11   6.3   3.5 |  -0.8  30.6  220  20 10   7.0   3.9
 14000   0.8  33.4  220  21 11   6.7   3.7 |   0.2  32.4  220  18  9   7.6   4.2
 13500   1.8  35.2  225  20 10   6.7   3.7 |   1.3  34.3  215  17  9   7.5   4.1
 13000   2.8  37.0  225  19 10   7.2   3.9 |   2.4  36.3  215  16  8   8.6   4.7
 12500   3.8  38.8  230  17  9   7.3   4.0 |   3.7  38.7  210  15  8   8.7   4.8
 12000   4.9  40.8  230  15  8   7.7   4.2 |   5.0  41.0  210  14  7   8.7   4.8
 11500   6.1  43.0  230  13  7   7.9   4.3 |   6.3  43.3  205  13  7   8.6   4.7
 11000   7.2  45.0  230  12  6   7.9   4.4 |   7.5  45.5  200  12  6   8.3   4.5
 10500   8.4  47.1  230  10  5   8.0   4.4 |   8.7  47.7  195  11  6   7.8   4.3
 10250   9.0  48.2  230   9  5   7.7   4.3 |   9.4  48.9  195  11  6  11.4   6.2
 10000   9.5  49.1  230   8  4   7.4   4.0 |  10.3  50.5  195  11  5  11.7   6.4
  9750  10.1  50.2  225   7  4   7.5   4.1 |  11.0  51.8  195  10  5   8.8   4.8
  9500  10.7  51.3  225   7  3   7.0   3.9 |  11.7  53.1  190  10  5   9.7   5.3
  9250  11.2  52.2  220   6  3   9.0   4.9 |  12.4  54.3  190  10  5   9.1   5.0
  9000  11.9  53.4  220   5  3   8.1   4.4 |  13.1  55.6  190   9  5   9.0   4.9
  8750  12.4  54.3  210   5  2   5.5   3.0 |  13.8  56.8  190   9  5   9.2   5.0
  8500  12.8  55.0  205   4  2   6.1   3.3 |  14.5  58.1  190   8  4   9.3   5.1
  8250  13.3  55.9  200   4  2   6.2   3.4 |  15.2  59.4  190   8  4   8.6   4.7
  8000  13.8  56.8  195   4  2   6.0   3.3 |  15.8  60.4  185   8  4   8.6   4.7
  7750  14.2  57.6  190   4  2   4.8   2.6 |  16.5  61.7  185   7  4   9.7   5.3
  7500  14.5  58.1  185   4  2   5.2   2.9 |  17.2  63.0  185   7  3   9.8   5.4
  7250  14.9  58.8  180   4  2   2.8   1.5 |  17.9  64.2  185   6  3   9.4   5.1
  7000  14.9  58.8  175   3  2  -0.5  -0.3 |  18.6  65.5  185   6  3   9.1   5.0
  6750  14.9  58.8  175   3  1  -0.3  -0.2 |  19.3  66.7  185   6  3   9.9   5.4
  6500  14.8  58.6  170   2  1  -0.3  -0.2 |  20.1  68.2  185   5  3  10.3   5.6
  6250  14.8  58.6  170   2  1   0.6   0.3 |  20.9  69.6  185   5  3  11.4   6.3
  6000  14.9  58.8  150   1  1   0.6   0.3 |  21.8  71.2  185   5  2  13.2   7.3
  5750  15.0  59.0  110   1  0   3.9   2.1 |  22.7  72.9  185   4  2   8.6   4.7
  5500  15.6  60.1  085   1  0  14.6   8.0 |  23.2  73.8  185   4  2  10.2   5.6

           09/22/2017 at 1500 MDT          |       09/22/2017 at 1800 MDT
                                           |
CAPE...   +68.2    LI...       -1.1        | CAPE...   +70.2    LI...       -1.4
CINH...    -8.0    K Index... +24.9        | CINH...   -20.1    K Index... +25.2
                                           |
Height Temperature  Wnd WndSpd  Lapse Rate | Temperature  Wnd WndSpd  Lapse Rate
ft MSL deg C deg F  Dir kt m/s  C/km F/kft | deg C deg F  Dir kt m/s  C/km F/kft
--------------------------------------------------------------------------------
 50000 -63.8 -82.8  215  34 18   2.0   1.1 | -63.5 -82.3  220  35 18   1.7   0.9
 45000 -60.3 -76.5  220  49 25   3.6   2.0 | -60.5 -76.9  225  46 24   3.5   1.9
 40000 -55.0 -67.0  220  53 27   4.6   2.5 | -55.2 -67.4  220  48 25   4.6   2.5
 38000 -51.3 -60.3  220  52 27   6.3   3.4 | -51.4 -60.5  220  48 25   6.4   3.5
 36000 -47.0 -52.6  215  51 26   6.3   3.5 | -47.1 -52.8  220  48 25   6.4   3.5
 34000 -42.7 -44.9  215  49 25   7.7   4.2 | -42.6 -44.7  220  47 24   7.9   4.4
 32000 -38.1 -36.6  215  46 24   7.7   4.2 | -37.9 -36.2  215  45 23   7.9   4.4
 30000 -33.4 -28.1  215  43 22   7.8   4.3 | -33.2 -27.8  215  43 22   7.6   4.2
 29000 -31.1 -24.0  210  42 22   7.8   4.3 | -30.9 -23.6  215  42 22   7.6   4.2
 28000 -28.8 -19.8  210  41 21   7.8   4.3 | -28.7 -19.7  215  41 21   7.7   4.2
 27000 -26.6 -15.9  210  39 20   7.1   3.9 | -26.6 -15.9  215  40 21   6.6   3.6
 26000 -24.5 -12.1  210  38 20   7.1   3.9 | -24.6 -12.3  215  39 20   6.6   3.6
 25000 -22.3  -8.1  210  37 19   7.1   3.9 | -22.7  -8.9  215  38 19   6.6   3.6
 24000 -20.4  -4.7  215  36 19   5.9   3.3 | -20.8  -5.4  215  36 19   6.2   3.4
 23000 -18.6  -1.5  215  35 18   6.0   3.3 | -18.9  -2.0  215  35 18   6.3   3.4
 22000 -16.8   1.8  215  33 17   6.1   3.3 | -17.1   1.2  215  33 17   6.3   3.5
 21000 -15.0   5.0  215  31 16   6.6   3.6 | -15.2   4.6  215  31 16   6.5   3.6
 20000 -13.0   8.6  215  29 15   6.6   3.6 | -12.8   9.0  215  28 14   6.5   3.6
 19500 -11.6  11.1  215  27 14   6.7   3.7 | -11.9  10.6  215  27 14   6.6   3.6
 19000 -10.6  12.9  215  26 13   7.4   4.0 | -10.9  12.4  215  26 13   7.2   3.9
 18500  -9.5  14.9  215  24 12   7.8   4.3 |  -9.8  14.4  215  24 12   7.6   4.2
 18000  -8.3  17.1  210  23 12   7.8   4.3 |  -8.7  16.3  210  23 12   7.6   4.2
 17500  -7.2  19.0  210  22 11   7.6   4.2 |  -7.5  18.5  210  22 11   8.5   4.7
 17000  -6.0  21.2  210  21 11   7.7   4.2 |  -6.3  20.7  210  21 11   8.4   4.6
 16500  -4.9  23.2  210  21 11   7.5   4.1 |  -5.0  23.0  205  20 10   8.9   4.9
 16000  -3.9  25.0  210  20 10   7.4   4.1 |  -3.7  25.3  205  19 10   9.1   5.0
 15500  -2.8  27.0  210  19 10   7.7   4.2 |  -2.4  27.7  200  18  9   9.1   5.0
 15000  -1.6  29.1  205  18  9   8.5   4.7 |  -1.0  30.2  200  18  9   9.2   5.1
 14500  -0.4  31.3  205  17  9   8.4   4.6 |   0.4  32.7  200  17  9   9.2   5.0
 14000   0.9  33.6  205  16  8   9.7   5.3 |   1.7  35.1  200  17  9   9.6   5.3
 13500   2.3  36.1  200  16  8   9.5   5.2 |   3.2  37.8  195  16  8   9.5   5.2
 13000   3.8  38.8  200  15  8   9.7   5.3 |   4.6  40.3  195  16  8   9.8   5.4
 12500   5.2  41.4  200  15  8   9.7   5.3 |   6.1  43.0  195  15  8   9.8   5.4
 12000   6.7  44.1  200  15  8   9.8   5.4 |   7.5  45.5  195  15  8   9.7   5.3
 11500   8.1  46.6  200  15  8   9.8   5.4 |   8.9  48.0  195  15  7   9.6   5.3
 11000   9.6  49.3  200  15  8   8.9   4.9 |  10.4  50.7  195  14  7   9.0   4.9
 10500  10.8  51.4  200  15  8   8.9   4.9 |  11.7  53.1  195  14  7   9.1   5.0
 10250  11.6  52.9  200  14  7  11.9   6.5 |  12.4  54.3  195  14  7  11.4   6.2
 10000  12.5  54.5  200  14  7  11.8   6.5 |  13.3  55.9  195  14  7  11.5   6.3
  9750  13.3  55.9  200  14  7   9.8   5.4 |  14.1  57.4  195  13  7  10.1   5.5
  9500  14.1  57.4  200  14  7  10.8   5.9 |  14.9  58.8  195  13  7  11.1   6.1
  9250  14.8  58.6  200  14  7   8.9   4.9 |  15.6  60.1  195  13  7   8.5   4.6
  9000  15.4  59.7  200  14  7   8.6   4.7 |  16.2  61.2  195  13  7   7.9   4.3
  8750  16.2  61.2  200  13  7  10.0   5.5 |  16.9  62.4  195  13  7  10.0   5.5
  8500  16.9  62.4  200  13  7   9.7   5.3 |  17.6  63.7  195  12  6   9.5   5.2
  8250  17.6  63.7  200  13  7   9.4   5.2 |  18.3  64.9  195  12  6   9.5   5.2
  8000  18.3  64.9  200  13  7   9.5   5.2 |  19.0  66.2  195  12  6   9.6   5.3
  7750  19.1  66.4  200  13  7  10.0   5.5 |  19.8  67.6  195  12  6   9.8   5.4
  7500  19.8  67.6  200  13  7  10.0   5.5 |  20.5  68.9  195  11  6   9.9   5.4
  7250  20.5  68.9  200  12  6   9.8   5.4 |  21.2  70.2  195  11  6   9.4   5.2
  7000  21.3  70.3  200  13  6   9.7   5.3 |  21.9  71.4  195  11  6   8.9   4.9
  6750  22.0  71.6  200  12  6  10.1   5.5 |  22.6  72.7  200  11  5   9.6   5.3
  6500  22.8  73.0  200  12  6  10.1   5.5 |  23.3  73.9  200  10  5   9.9   5.4
  6250  23.5  74.3  200  11  6  10.8   5.9 |  24.0  75.2  200   9  5   9.9   5.4
  6000  24.4  75.9  200  11  6  12.0   6.6 |  24.8  76.6  200   9  5  10.3   5.6
  5750  25.2  77.4  200  11  6   9.7   5.3 |  25.5  77.9  200   9  4   8.9   4.9
  5500  25.9  78.6  200  10  5  12.2   6.7 |  26.1  79.0  200   7  4   8.0   4.4
________________________________________________________________________________

This product is issued twice per day, once by approximately 0630 MST/0730 MDT
(1330 UTC) and again by approximately 1830 MST/1930 MDT (0130 UTC).  It is not
continuously monitored nor updated after its initial issuance.

The information contained herein is based on rawinsonde observation and/or
numerical weather prediction model data taken near the old Stapleton
Airport site in Denver, Colorado at

                   North Latitude:  39 deg 46 min 5.016 sec
                   West Longitude: 104 deg 52 min 9.984 sec
                   Elevation: 5285 feet (1611 meters)

and may not be representative of other areas along the Front Range of the
Colorado Rocky Mountains.  Note that some elevations in numerical weather
prediction models differ from actual station elevations, which can lead to
data which appear to be below ground.  Erroneous data such as these should
not be used.

The content and format of this report as well as the issuance times are subject
to change without prior notice.  Comments and suggestions are welcome and should
be directed to one of the addresses or phone numbers shown at the bottom of this
page.  To expedite a response to comments, be sure to mention your interest in
the soaring forecast.

DEFINITIONS:

CAPE (Convective Available Potential Energy) - An integrated measure of the
     energy available for convective development, also known as the positive
     area on a thermodynamic diagram.  Units are Joules per kilogram.  Larger
     values are indicative of greater instability and the possibility of
     stronger convective activity, including thunderstorms.  Values around or
     greater than 1000 suggest the possibility of severe weather should
     convective activity develop.

CINH (Convective Inhibition) - An integrated measure of the amount of energy
     needed to initiate convective activity, also known as the negative area on
     a thermodynamic diagram.  Units are Joules per kilogram.  The more negative
     this number, the more energy is required to initiate convection.  This
     inhibitive energy can be overcome through surface heating, cooling aloft,
     lifting mechanisms (orographic, frontal, gravity waves, etc.)

Convective Condensation Level - The height to which an air parcel possessing the
     average saturation mixing ratio in the lowest 4000 feet of the airmass,
     if heated sufficiently from below, will rise dry adiabatically until it
     just becomes saturated.  It estimates the base of cumulus clouds that are
     produced by surface heating only.

Convection Temperature (ConvectionT) - The surface temperature required to make
     the airmass dry adiabatic up to the given level.  It can be considered a
     "trigger temperature" for that level.

Freezing Level - The height where the temperature is zero degrees Celsius.

Height of Stable Layer - The height (between 12,000 and 18,000 feet above
     mean sea level) where the smallest lapse rate exists.  The location and
     existence of this feature is important in the generation of mountain
     waves.

K Index - A measure of stability which combines the temperature difference
     between approximately 5,000 and 18,000 feet above the surface, the amount
     of moisture at approximately 5,000 feet above the surface, and a measure
     of the dryness at approximately 10,000 feet above the surface.  Larger
     positive numbers indicate more instability and a greater likelihood of
     thunderstorm development.  One interpretation of K index values regarding
     soaring in the western United States is given in WMO Technical Note 158
     and is reproduced in the following table:

          below -10    no or weak thermals
           -10 to 5    dry thermals or 1/8 cumulus with moderate thermals
            5 to 15    good soaring conditions
           15 to 20    good soaring conditions with occasional showers
           20 to 30    excellent soaring conditions, but increasing
                       probability of showers and thunderstorms
           above 30    more than 60 percent probability of thunderstorms

Lapse Rate - The change with height of the temperature. Negative values indicate
     inversions.

Lifted Condensation Level - The height to which an air parcel possessing the
     average dew point in the lowest 4000 feet of the airmass and the forecast
     maximum temperature must be lifted dry adiabatically to attain saturation.

Lifted Index (LI) - The difference between the environmental temperature at a
     level approximately 18,000 feet above the surface and the temperature of
     an air parcel lifted dry adiabatically from the surface to its lifted
     condensation level and then pseudoadiabatically thereafter to this same
     level.  The parcel`s initial temperature is the forecast maximum
     temperature and its dew point is the average dew point in the lowest 4000
     feet of the airmass.  Negative values are indicative of instability with
     positive values showing stable conditions.

Lift Rate - An experimental estimate of the strength of thermals.  It is
     computed the same way as the maximum rate of lift but uses the actual
     level rather than the maximum height of thermals in the calculation.
     Also, none of the empirical adjustments based on cloudiness and K-index
     are applied to these calculations.

Maximum Height of Thermals - The height where the dry adiabat through the
     forecast maximum temperature intersects the environmental temperature.

Maximum Rate of Lift - An estimate of the maximum strength of thermals.  It
     is computed from an empirical formula which combines the expected maximum
     height of thermals with the difference in the environmental temperatures
     between the maximum height of thermals and the temperature 4,000 feet
     above the ground.  After this computation, further empirical adjustments
     are made based on the value of the K-index and the amount and opacity of
     middle and high level cloudiness expected between the time of trigger
     temperature and the time of overdevelopment.

Middle/High Clouds - The amount and opacity of middle (altostratus, altocumulus)
     or high (cirrus, cirrostratus, cirrocumulus) clouds.  Broken means that
     between 60% and 90% of the sky is covered by the cloud, with overcast
     conditions occurring when more than 90% of the sky is covered by the cloud.
     Thin implies that the clouds are predominantly transparent, meaning that
     some sunlight is reaching the ground, in contrast to opaque which suggests
     that little sunlight is reaching the ground.

Potential Height of Wave - The minimum of the following two heights:
     1. Level above the height of stable layer (or 14,000 feet if none exists)
        where the wind direction changes by 30 degrees or more
     2. Level above the height of stable layer (or 14,000 feet if none exists)
        where the wind speed no longer increases with height

PVA/NVA - Positive vorticity advection (PVA)/negative vorticity advection (NVA)
     on the 500 millibar isobaric surface (approximately 18,000 feet above mean
     sea level).  Weak PVA has been shown to assist in mountain wave soaring.

Soaring Window - The time between the time the trigger temperature is reached
                 and the time of overdevelopment.

Thermal Index - The difference between the environmental temperature and the
     temperature at a particular level determined by following the dry adiabat
     through the forecast maximum temperature up to that level.  Negative values
     are indicative of thermal lift.

Thermal Soaring Index - An adjective rating (for sailplanes) based on the
     computed maximum rate of lift, and the wind speed and middle and high
     cloud cover expected during the soaring window (the time of the trigger
     temperature and the time of overdevelopment) according to the following:

                 Maximum rate of lift        Adjective Rating
                      >= 800 fpm                 Excellent
                 >= 400 and < 800 fpm              Good
                 >= 200 and < 400 fpm              Fair
                       < 200 fpm                   Poor

Time of Overdevelopment - The time one or more of the following phenomena,
     which essentially shut off thermal lift, is expected to occur:
     1. formation of broken to overcast convective cloud cover
     2. formation of scattered to numerous downbursts
     3. initiation of widespread precipitation

Time of Trigger Temperature - The time the surface temperature is expected to
     reach the trigger temperature.

Trigger Temperature - The surface temperature required to make the first 4000
     feet of the atmosphere dry adiabatic.

Wave Soaring Index - An empirical, adjective rating (for sailplanes) which
     attempts to combine a variety of phenomena important in mountain wave
     soaring into a single index number.  Objective points are assigned to
     these phenomena: wind speed and direction at 14,000 ft MSL, the static
     stability in the 12,000-18,000 ft MSL layer, the wind speed gradient above
     the stable layer, jet stream location and frontal and upper trough
     movements.

042613



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.