Soaring Guidance
Issued by NWS Pueblo, CO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7

000
UXUS97 KPUB 181205
SRGPUB

Soaring Forecast
National Weather Service Pueblo, Colorado
0605 MDT Monday, September 18, 2017

This forecast is for Monday, September 18, 2017:

If the trigger temperature of 61.3 F/16.3 C is reached...then
   Thermal Soaring Index....................... Excellent
   Maximum rate of lift........................ 1317 ft/min (6.7 m/s)
   Maximum height of thermals.................. 21727 ft MSL (14098 ft AGL)

Forecast maximum temperature................... 77.0 F/25.5 C
Time of trigger temperature.................... 0845 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................. 18466 ft MSL (10836 ft AGL)
Thermal soaring outlook for Tuesday 09/19...... Excellent

Wave Soaring Index............................. Not available

Remarks...

Sunrise/Sunset.................... 06:43:51 / 19:02:42 MDT
Total possible sunshine........... 12 hr 18 min 51 sec (738 min 51 sec)
Altitude of sun at 12:53:17 MDT... 52.58 degrees

Upper air data from numerical model forecast valid on 09/18/2017 at 0600 MDT

Freezing level.................. 13310 ft MSL (5681 ft AGL)
Convective condensation level... 16696 ft MSL (9067 ft AGL)
Lifted condensation level....... 19091 ft MSL (11462 ft AGL)
Lifted index.................... -4.0
K index......................... +15.2

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  -60.1 -76.2   250   22   11   1.6   0.9      M     M       M      M    M
 45000  -57.4 -71.3   245   26   13   2.3   1.3      M     M       M      M    M
 40000  -53.7 -64.7   265   17    9   4.2   2.3      M     M       M      M    M
 38000  -50.3 -58.5   265   17    9   5.8   3.2      M     M       M      M    M
 36000  -46.8 -52.2   270   17    9   5.8   3.2      M     M       M      M    M
 34000  -44.0 -47.2   265   17    9   4.0   2.2      M     M       M      M    M
 32000  -41.6 -42.9   260   18    9   4.0   2.2      M     M       M      M    M
 30000  -38.1 -36.6   260   18    9   7.3   4.0   30.3  86.6     4.1      M    M
 29000  -35.9 -32.6   260   18    9   7.3   4.0   29.4  84.8     3.4      M    M
 28000  -33.7 -28.7   260   18    9   7.4   4.0   28.5  83.4     2.8      M    M
 27000  -31.3 -24.3   260   18    9   8.4   4.6   27.8  82.1     2.3      M    M
 26000  -28.8 -19.8   260   18    9   8.4   4.6   27.3  81.1     1.9      M    M
 25000  -26.3 -15.3   265   17    9   8.4   4.6   26.9  80.4     1.5      M    M
 24000  -23.1  -9.6   265   17    9   8.1   4.5   26.2  79.2     1.0      M    M
 23000  -20.7  -5.3   260   16    8   8.1   4.5   25.6  78.1     0.5      M    M
 22000  -18.3  -0.9   260   16    8   8.2   4.5   25.1  77.2     0.1      M    M
 21000  -16.0   3.2   260   15    8   7.2   4.0   24.3  75.7    -0.7   1240  6.3
 20000  -13.9   7.0   255   14    7   7.3   4.0   23.4  74.1    -1.5   1146  5.8
 19500  -12.8   9.0   255   14    7   7.3   4.0   23.0  73.4    -1.8   1099  5.6
 19000  -11.8  10.8   255   14    7   6.0   3.3   22.6  72.7    -2.2   1053  5.4
 18500  -11.0  12.2   260   13    7   5.2   2.8   21.8  71.3    -3.0   1017  5.2
 18000  -10.3  13.5   260   12    6   5.2   2.8   21.1  69.9    -3.8    981  5.0
 17500   -9.5  14.9   265   12    6   6.5   3.6   20.4  68.7    -4.4    940  4.8
 17000   -8.5  16.7   270   12    6   6.4   3.5   19.8  67.7    -5.0    898  4.6
 16500   -7.6  18.3   275   12    6   7.1   3.9   19.3  66.8    -5.5    854  4.3
 16000   -6.5  20.3   280   13    7   7.3   4.0   18.9  66.0    -5.9    807  4.1
 15500   -5.4  22.3   285   13    7   7.6   4.2   18.5  65.3    -6.3    760  3.9
 15000   -4.3  24.3   285   13    7   8.1   4.4   18.2  64.8    -6.7    710  3.6
 14500   -3.1  26.4   290   13    6   8.1   4.5   18.0  64.3    -7.0    660  3.4
 14000   -1.8  28.8   295   12    6   8.6   4.7   17.7  63.9    -7.2    608  3.1
 13500   -0.6  30.9   300   12    6   8.4   4.6   17.6  63.6    -7.5    555  2.8
 13000    0.8  33.4   300   11    6  10.4   5.7   17.5  63.5    -7.6    500  2.5
 12500    2.1  35.8   305   11    6   7.9   4.3   17.4  63.3    -7.8    445  2.3
 12000    3.3  37.9   305   11    6   8.3   4.5   17.1  62.8    -8.1    394  2.0
 11750    3.9  39.0   305   11    6   8.3   4.6   17.0  62.6    -8.2    368  1.9
 11500    4.5  40.1   305   11    6   8.1   4.4   16.9  62.4    -8.4    343  1.7
 11250    5.1  41.2   310   10    5   7.9   4.3   16.8  62.2    -8.5    317  1.6
 11000    5.7  42.3   310   10    5   8.1   4.4   16.6  61.9    -8.7    292  1.5
 10750    6.3  43.3   310   10    5   8.0   4.4   16.5  61.7    -8.8    267  1.4
 10500    6.9  44.4   310   10    5   8.4   4.6   16.4  61.4    -9.0    242  1.2
 10250    7.6  45.7   310   10    5   9.2   5.1   16.3  61.3    -9.1    214  1.1
 10000    8.3  46.9   310    9    5   8.7   4.8   16.2  61.2    -9.2    187  0.9
  9750    8.9  48.0   310    9    5   8.2   4.5   16.1  61.0    -9.3    161  0.8
  9500    9.5  49.1   310    9    5   8.5   4.7   16.0  60.8    -9.5    135  0.7
  9250   10.1  50.2   310    9    5   7.7   4.2   15.9  60.7    -9.6    109  0.6
  9000   10.6  51.1   305   10    5   6.1   3.4   15.7  60.3    -9.9     87  0.4
  8750   11.0  51.8   305   10    5   5.3   2.9   15.4  59.7   -10.2     68  0.3
  8500   11.4  52.5   300   10    5   6.6   3.6   15.1  59.1   -10.6     49  0.2
  8250   11.7  53.1   300   10    5   1.1   0.6   14.7  58.5   -11.0     31  0.2
  8000   11.1  52.0   295   10    5 -17.0  -9.3   13.5  56.2   -12.3     41  0.2
  7750    7.1  44.8   275    5    2 -10.2  -5.6    8.2  46.7   -17.9    147  0.7
  7500      M     M     M    M    M     M     M      M     M       M      M    M
  7250      M     M     M    M    M     M     M      M     M       M      M    M
  7000      M     M     M    M    M     M     M      M     M       M      M    M
  6750      M     M     M    M    M     M     M      M     M       M      M    M

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

           09/18/2017 at 0900 MDT          |       09/18/2017 at 1200 MDT
                                           |
CAPE...   +12.9    LI...       +2.1        | CAPE...    +1.1    LI...       +1.5
CINH...   -56.8    K Index...  +9.0        | CINH...     0.0    K Index...  +4.3
                                           |
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 -60.9 -77.6  255  19 10   0.7   0.4 | -61.3 -78.3  250  18  9   0.1   0.0
 45000 -59.2 -74.6  260  21 11   3.0   1.7 | -60.4 -76.7  265  21 11   3.0   1.7
 40000 -54.3 -65.7  280  18  9   4.9   2.7 | -55.6 -68.1  280  26 13   5.0   2.8
 38000 -50.9 -59.6  290  17  9   5.7   3.1 | -52.2 -62.0  295  21 11   5.6   3.1
 36000 -47.5 -53.5  305  17  9   5.7   3.1 | -48.8 -55.8  315  17  9   5.6   3.1
 34000 -43.8 -46.8  310  18  9   6.4   3.5 | -44.6 -48.3  320  16  8   7.9   4.3
 32000 -39.9 -39.8  310  19 10   6.4   3.5 | -39.8 -39.6  320  16  8   7.9   4.3
 30000 -36.0 -32.8  305  18  9   6.6   3.6 | -34.9 -30.8  320  17  9   8.3   4.6
 29000 -34.0 -29.2  300  17  9   6.6   3.6 | -32.4 -26.3  315  18  9   8.3   4.6
 28000 -32.1 -25.8  295  17  8   6.6   3.6 | -29.9 -21.8  315  19 10   8.4   4.6
 27000 -30.0 -22.0  290  16  8   7.2   3.9 | -27.6 -17.7  315  19 10   7.2   3.9
 26000 -27.8 -18.0  285  15  8   7.2   4.0 | -25.4 -13.7  315  17  9   7.1   3.9
 25000 -25.7 -14.3  280  15  8   7.2   4.0 | -23.3  -9.9  310  16  8   7.1   3.9
 24000 -22.9  -9.2  280  15  8   7.7   4.2 | -20.7  -5.3  310  14  7   6.7   3.7
 23000 -20.6  -5.1  280  14  7   7.7   4.2 | -18.7  -1.7  305  13  7   6.7   3.7
 22000 -18.3  -0.9  280  14  7   7.6   4.2 | -16.7   1.9  300  12  6   6.6   3.6
 21000 -15.8   3.6  280  13  7   8.5   4.7 | -14.6   5.7  295  11  6   7.3   4.0
 20000 -13.3   8.1  280  12  6   8.5   4.7 | -12.4   9.7  290  11  6   7.4   4.0
 19500 -12.0  10.4  280  11  6   8.5   4.7 | -11.3  11.7  290  11  6   7.4   4.1
 19000 -10.8  12.6  280  10  5   6.6   3.6 | -10.2  13.6  285  11  5   6.8   3.7
 18500 -10.0  14.0  280  10  5   5.8   3.2 |  -9.2  15.4  280  11  6   6.6   3.6
 18000  -9.1  15.6  275  10  5   5.7   3.1 |  -8.3  17.1  280  11  6   6.5   3.6
 17500  -8.4  16.9  275  10  5   4.7   2.6 |  -7.3  18.9  275  11  6   6.0   3.3
 17000  -7.7  18.1  275  10  5   4.8   2.6 |  -6.4  20.5  275  11  6   6.2   3.4
 16500  -7.0  19.4  275  10  5   5.7   3.1 |  -5.6  21.9  270  10  5   4.6   2.5
 16000  -6.2  20.8  275  10  5   6.0   3.3 |  -5.0  23.0  270  10  5   4.5   2.5
 15500  -5.4  22.3  280  10  5   6.5   3.6 |  -4.4  24.1  270  10  5   5.2   2.9
 15000  -4.3  24.3  280  10  5   7.3   4.0 |  -3.5  25.7  270  10  5   6.3   3.5
 14500  -3.3  26.1  285  10  5   7.4   4.1 |  -2.6  27.3  275   9  5   6.7   3.7
 14000  -2.0  28.4  285  10  5   8.7   4.8 |  -1.5  29.3  275   9  5   8.4   4.6
 13500  -0.7  30.7  290  10  5   8.6   4.7 |  -0.4  31.3  275   9  4   8.3   4.6
 13000   0.5  32.9  295  10  5   8.9   4.9 |   0.8  33.4  280   7  4   8.5   4.7
 12500   1.7  35.1  300   9  5   7.2   3.9 |   2.1  35.8  280   6  3   9.6   5.3
 12000   2.8  37.0  300   9  4   7.4   4.1 |   3.4  38.1  280   5  2   8.9   4.9
 11750   3.4  38.1  305   8  4   7.4   4.0 |   4.1  39.4  280   4  2   8.9   4.9
 11500   3.9  39.0  305   8  4   8.0   4.4 |   4.8  40.6  280   4  2  10.4   5.7
 11250   4.5  40.1  305   7  4   8.2   4.5 |   5.6  42.1  280   4  2  10.4   5.7
 11000   5.1  41.2  310   7  4   7.6   4.2 |   6.3  43.3  280   4  2   9.0   5.0
 10750   5.6  42.1  310   7  4   7.5   4.1 |   7.0  44.6  280   4  2   8.6   4.7
 10500   6.2  43.2  310   7  3   8.2   4.5 |   7.7  45.9  280   3  2  10.5   5.7
 10250   6.9  44.4  315   7  3   9.3   5.1 |   8.5  47.3  280   3  2  11.9   6.5
 10000   7.5  45.5  315   7  3   9.1   5.0 |   9.3  48.7  280   3  2  10.3   5.6
  9750   8.2  46.8  315   7  4   8.6   4.7 |  10.1  50.2  280   3  2   9.7   5.3
  9500   8.8  47.8  310   7  4   9.2   5.1 |  10.8  51.4  285   3  2  10.2   5.6
  9250   9.5  49.1  310   7  4   7.3   4.0 |  11.6  52.9  285   3  2   8.8   4.8
  9000  10.0  50.0  310   7  3   7.5   4.1 |  12.2  54.0  285   3  1   9.2   5.0
  8750  10.6  51.1  310   7  3   9.5   5.2 |  13.0  55.4  285   3  1  10.9   6.0
  8500  11.3  52.3  310   6  3   9.0   4.9 |  13.8  56.8  285   3  1  10.3   5.7
  8250  11.9  53.4  305   6  3   8.2   4.5 |  14.6  58.3  285   3  1  11.1   6.1
  8000  12.5  54.5  305   6  3  10.1   5.5 |  15.6  60.1  285   3  1  17.5   9.6
  7750  13.3  55.9  300   5  2  15.3   8.4 |  17.2  63.0  285   2  1  26.5  14.5
  7500     M     M    M   M  M     M     M |     M     M    M   M  M     M     M
  7250     M     M    M   M  M     M     M |     M     M    M   M  M     M     M
  7000     M     M    M   M  M     M     M |     M     M    M   M  M     M     M
  6750     M     M    M   M  M     M     M |     M     M    M   M  M     M     M

           09/18/2017 at 1500 MDT          |       09/18/2017 at 1800 MDT
                                           |
CAPE...   +19.5    LI...       +1.1        | CAPE...   +12.3    LI...       +0.8
CINH...    -0.2    K Index...  +9.7        | CINH...    -1.6    K Index... +12.7
                                           |
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 -62.0 -79.6  255  19 10   0.6   0.3 | -63.1 -81.6  260  18  9   0.3   0.2
 45000 -60.6 -77.1  270  22 12   2.3   1.3 | -62.0 -79.6  275  20 10   2.6   1.4
 40000 -56.7 -70.1  280  25 13   5.9   3.3 | -57.6 -71.7  280  20 10   7.7   4.2
 38000 -53.0 -63.4  290  18  9   6.2   3.4 | -53.2 -63.8  275  15  8   7.4   4.0
 36000 -49.3 -56.7  305  12  6   6.2   3.4 | -48.8 -55.8  270  10  5   7.4   4.1
 34000 -44.7 -48.5  310  12  6   8.3   4.6 | -44.0 -47.2  270  12  6   8.1   4.4
 32000 -39.8 -39.6  305  14  7   8.3   4.6 | -39.2 -38.6  275  15  8   8.1   4.5
 30000 -34.7 -30.5  300  15  8   8.5   4.7 | -34.2 -29.6  275  17  9   8.4   4.6
 29000 -32.1 -25.8  295  15  8   8.5   4.7 | -31.6 -24.9  270  17  9   8.5   4.6
 28000 -29.6 -21.3  295  16  8   8.6   4.7 | -29.1 -20.4  270  17  9   8.5   4.7
 27000 -27.1 -16.8  290  15  8   8.1   4.5 | -26.7 -16.1  270  17  9   8.0   4.4
 26000 -24.7 -12.5  290  15  8   8.1   4.5 | -24.2 -11.6  270  17  9   8.0   4.4
 25000 -22.2  -8.0  290  15  8   8.1   4.4 | -21.8  -7.2  270  17  9   8.0   4.4
 24000 -19.4  -2.9  290  14  7   7.0   3.8 | -18.9  -2.0  270  16  8   7.7   4.2
 23000 -17.3   0.9  285  14  7   7.0   3.8 | -16.6   2.1  270  15  8   7.7   4.2
 22000 -15.3   4.5  285  13  7   7.0   3.8 | -14.3   6.3  270  15  8   7.7   4.2
 21000 -13.1   8.4  285  13  7   7.4   4.1 | -12.2  10.0  270  14  7   7.0   3.8
 20000 -10.9  12.4  285  13  6   7.4   4.1 | -10.1  13.8  270  14  7   7.0   3.8
 19500  -9.8  14.4  290  13  6   7.5   4.1 |  -9.0  15.8  270  14  7   7.1   3.9
 19000  -8.7  16.3  290  12  6   6.2   3.4 |  -8.0  17.6  270  14  7   5.9   3.2
 18500  -7.8  18.0  285  12  6   5.9   3.2 |  -7.2  19.0  270  14  7   5.6   3.1
 18000  -7.0  19.4  285  12  6   5.7   3.1 |  -6.4  20.5  270  14  7   5.6   3.0
 17500  -6.3  20.7  280  12  6   4.2   2.3 |  -5.7  21.7  270  14  7   5.0   2.8
 17000  -5.7  21.7  275  12  6   4.4   2.4 |  -5.0  23.0  265  14  7   5.1   2.8
 16500  -5.1  22.8  275  12  6   5.8   3.2 |  -4.2  24.4  265  13  7   7.2   3.9
 16000  -4.3  24.3  270  10  5   6.4   3.5 |  -3.2  26.2  260  12  6   7.7   4.2
 15500  -3.5  25.7  265   9  5   7.4   4.0 |  -2.2  28.0  250  10  5   8.2   4.5
 15000  -2.3  27.9  260   7  4   8.2   4.5 |  -1.0  30.2  250   9  5   8.5   4.6
 14500  -1.2  29.8  255   5  3   8.3   4.6 |   0.3  32.5  245   8  4   8.5   4.7
 14000   0.1  32.2  250   4  2   9.0   4.9 |   1.6  34.9  245   8  4   9.1   5.0
 13500   1.5  34.7  245   3  2   8.9   4.9 |   2.9  37.2  240   8  4   8.8   4.8
 13000   2.8  37.0  230   3  1   9.3   5.1 |   4.4  39.9  235   7  4  10.5   5.8
 12500   4.1  39.4  215   3  1   8.5   4.7 |   5.7  42.3  230   7  4   8.0   4.4
 12000   5.4  41.7  200   3  1   8.0   4.4 |   6.8  44.2  225   7  4   7.0   3.9
 11750   6.0  42.8  195   3  2   8.3   4.5 |   7.3  45.1  220   7  4   7.2   3.9
 11500   6.6  43.9  190   3  2   9.4   5.2 |   7.9  46.2  215   7  4   8.2   4.5
 11250   7.4  45.3  185   3  2   9.8   5.4 |   8.5  47.3  210   8  4   8.2   4.5
 11000   8.1  46.6  180   4  2   9.3   5.1 |   9.1  48.4  210   8  4   7.1   3.9
 10750   8.8  47.8  180   4  2   9.1   5.0 |   9.6  49.3  205   8  4   6.6   3.6
 10500   9.5  49.1  175   4  2   9.6   5.3 |  10.1  50.2  200   8  4   7.7   4.3
 10250  10.2  50.4  175   4  2  10.2   5.6 |  10.7  51.3  200   8  4   9.1   5.0
 10000  11.0  51.8  175   4  2   9.8   5.4 |  11.4  52.5  195   8  4   7.9   4.4
  9750  11.7  53.1  170   4  2   9.8   5.4 |  11.9  53.4  190   9  4   7.2   3.9
  9500  12.4  54.3  170   4  2   9.4   5.2 |  12.5  54.5  185   9  4   7.1   3.9
  9250  13.1  55.6  170   4  2  10.9   6.0 |  13.0  55.4  185   9  5   8.2   4.5
  9000  14.0  57.2  170   4  2  10.6   5.8 |  13.7  56.7  180   9  5   9.6   5.3
  8750  14.7  58.5  165   4  2   9.2   5.0 |  14.4  57.9  180   9  5   9.4   5.2
  8500  15.4  59.7  165   5  2   8.9   4.9 |  15.1  59.2  175   9  4   9.7   5.3
  8250  16.1  61.0  165   5  2  11.6   6.3 |  15.8  60.4  170   8  4   8.9   4.9
  8000  17.2  63.0  165   5  2  17.2   9.5 |  16.5  61.7  170   8  4   9.8   5.4
  7750  18.5  65.3  165   4  2  18.1   9.9 |  17.3  63.1  170   7  3  13.7   7.5
  7500     M     M    M   M  M     M     M |     M     M    M   M  M     M     M
  7250     M     M    M   M  M     M     M |     M     M    M   M  M     M     M
  7000     M     M    M   M  M     M     M |     M     M    M   M  M     M     M
  6750     M     M    M   M  M     M     M |     M     M    M   M  M     M     M
________________________________________________________________________________

This product is issued twice per day, once by approximately 0630 MST/0730 MDT
(1330 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 Air Force Academy
in Colorado Springs, Colorado at

                   North Latitude:  38 deg 58 min 48.000 sec
                   West Longitude: 104 deg 49 min 12.000 sec
                   Elevation: 6572 feet (2003 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.

CIN (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.