Soaring Guidance
Issued by NWS Pueblo, CO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7
000
UXUS97 KPUB 201233
SRGPUB

Soaring Forecast
National Weather Service Pueblo, Colorado
1233 UTC Tuesday, September 20, 2016

This forecast is for Tuesday, September 20, 2016:

If the trigger temperature of 78.0 F/25.6 C is reached...then
   Thermal Soaring Index....................... Good
   Maximum rate of lift........................ 634 ft/min (3.2 m/s)
   Maximum height of thermals.................. 17114 ft MSL (10356 ft AGL)

Forecast maximum temperature................... 81.0 F/27.7 C
Time of trigger temperature.................... 1300 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 8419 ft MSL (1661 ft AGL)
Thermal soaring outlook for Wednesday 09/21.... Good

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

Remarks...

Sunrise/Sunset.................... 06:45:22 / 18:59:52 MST
Total possible sunshine........... 12 hr 14 min 30 sec (734 min 30 sec)
Altitude of sun at 12:52:08 MST... 51.76 degrees

Upper air data from numerical model forecast valid on 09/20/2016 at 0500 MST

Freezing level.................. 16196 ft MSL (9438 ft AGL)
Convective condensation level... 20752 ft MSL (13994 ft AGL)
Lifted condensation level....... 19435 ft MSL (12677 ft AGL)
Lifted index.................... +1.2
K index......................... +8.2

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  -66.3 -87.3   275   41   21   1.7   1.0      M     M       M      M    M
 45000  -62.4 -80.3   275   56   29   4.9   2.7      M     M       M      M    M
 40000  -54.3 -65.7   280   71   36   6.9   3.8      M     M       M      M    M
 38000  -50.1 -58.2   280   65   33   6.9   3.8      M     M       M      M    M
 36000  -46.0 -50.8   280   59   30   7.0   3.8      M     M       M      M    M
 34000  -40.7 -41.3   270   53   27   9.0   4.9      M     M       M      M    M
 32000  -35.3 -31.5   260   49   25   9.0   4.9      M     M       M      M    M
 30000  -31.1 -24.0   255   42   21   6.6   3.6   39.1 102.4     9.1      M    M
 29000  -28.7 -19.7   250   36   19   6.6   3.6   37.7  99.9     8.1      M    M
 28000  -26.6 -15.9   245   33   17   7.4   4.0   36.7  98.0     7.4      M    M
 27000  -24.4 -11.9   250   30   16   7.3   4.0   35.7  96.2     6.7      M    M
 26000  -22.2  -8.0   255   28   14   7.3   4.0   34.8  94.6     6.1      M    M
 25000  -20.0  -4.0   260   26   13   7.2   4.0   34.0  93.2     5.5      M    M
 24000  -17.9  -0.2   260   23   12   7.1   3.9   32.9  91.3     4.7      M    M
 23000  -15.8   3.6   260   20   11   7.1   3.9   32.0  89.6     3.9      M    M
 22000  -13.6   7.5   260   18    9   7.2   3.9   31.1  88.0     3.3      M    M
 21000  -11.5  11.3   250   16    8   7.3   4.0   30.2  86.3     2.5      M    M
 20000   -9.3  15.3   245   14    7   7.3   4.0   29.3  84.8     1.7      M    M
 19500   -8.2  17.2   240   14    7   7.3   4.0   29.0  84.1     1.4      M    M
 19000   -7.1  19.2   240   13    7   7.8   4.3   28.6  83.5     1.1      M    M
 18500   -6.0  21.2   235   12    6   7.7   4.2   28.2  82.8     0.8      M    M
 18000   -4.8  23.4   235   12    6   8.2   4.5   27.9  82.3     0.5      M    M
 17500   -3.6  25.5   235   11    6   8.4   4.6   27.7  81.8     0.2      M    M
 17000   -2.4  27.7   230   11    6   8.6   4.7   27.5  81.5    -0.0   1031  5.2
 16500   -1.1  30.0   230   11    6   9.0   4.9   27.3  81.2    -0.2    977  5.0
 16000    0.3  32.5   225   11    6   8.9   4.9   27.2  80.9    -0.3    922  4.7
 15500    1.6  34.9   220   11    6   9.1   5.0   27.1  80.7    -0.4    868  4.4
 15000    2.9  37.2   220   12    6   9.1   5.0   27.0  80.5    -0.6    813  4.1
 14500    4.9  40.8   220   12    6   9.0   4.9   26.8  80.2    -0.8    731  3.7
 14000    6.2  43.2   220   12    6   9.0   4.9   26.7  80.0    -0.9    676  3.4
 13500    7.6  45.7   215   12    6   9.4   5.2   26.6  79.8    -1.0    621  3.2
 13000    9.0  48.2   215   12    6   9.4   5.2   26.5  79.7    -1.1    565  2.9
 12500   10.4  50.7   215   12    6   9.3   5.1   26.5  79.7    -1.2    509  2.6
 12000   11.7  53.1   215   12    6   9.2   5.0   26.4  79.5    -1.3    453  2.3
 11750   12.4  54.3   220   12    6   9.1   5.0   26.3  79.4    -1.4    426  2.2
 11500   13.1  55.6   220   12    6  10.0   5.5   26.3  79.3    -1.4    398  2.0
 11250   13.8  56.8   220   12    6   9.4   5.2   26.3  79.4    -1.4    368  1.9
 11000   14.4  57.9   220   12    6   8.3   4.5   26.2  79.2    -1.5    342  1.7
 10750   15.1  59.2   225   12    6   8.5   4.7   26.1  79.1    -1.6    316  1.6
 10500   15.7  60.3   225   11    6   8.9   4.9   26.0  78.9    -1.7    290  1.5
 10250   16.4  61.5   225   11    6   9.5   5.2   26.0  78.8    -1.8    262  1.3
 10000   17.1  62.8   230   11    6   8.6   4.7   26.0  78.8    -1.8    234  1.2
  9750   17.7  63.9   230   11    6   8.1   4.4   25.8  78.5    -1.9    208  1.1
  9500   18.3  64.9   235   11    6   8.0   4.4   25.7  78.3    -2.1    183  0.9
  9250   18.9  66.0   235   11    6   7.8   4.3   25.6  78.0    -2.2    158  0.8
  9000   19.4  66.9   240   11    5   7.8   4.3   25.4  77.8    -2.4    133  0.7
  8750   20.0  68.0   240   10    5   7.3   4.0   25.3  77.5    -2.6    109  0.6
  8500   20.4  68.7   245   10    5   4.1   2.2   25.0  77.0    -2.8     88  0.4
  8250   20.5  68.9   245   10    5  -0.8  -0.4   24.4  75.9    -3.5     78  0.4
  8000   20.6  69.1   245    9    5   8.1   4.4   23.7  74.7    -4.1     67  0.3
  7750   20.7  69.3   250    9    5 -22.4 -12.3   23.1  73.6    -4.8     57  0.3
  7500   17.6  63.7   255    9    5 -36.1 -19.8   19.5  67.1    -8.4    143  0.7
  7250   16.3  61.3   260    8    4 -10.3  -5.7   17.8  64.0   -10.2    176  0.9
  7000   14.9  58.8   270    8    4 -32.3 -17.7   16.0  60.8   -12.0    210  1.1
  6750      M     M     M    M    M     M     M      M     M       M      M    M

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

           09/20/2016 at 0800 MST          |       09/20/2016 at 1100 MST
                                           |
K index... +8.3  LI... +275.3              | K index... +13.5  LI... +273.8
CAPE... 0.0  CIN... -44.0                  | CAPE... 0.0  CIN... -42.1
                                           |
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 -66.2 -87.2  275  38 20   1.9   1.0 | -66.3 -87.3  275  37 19   2.3   1.2
 45000 -61.8 -79.2  275  55 28   4.8   2.7 | -61.8 -79.2  275  55 28   4.2   2.3
 40000 -54.1 -65.4  280  76 39   7.2   4.0 | -54.7 -66.5  275  80 41   8.2   4.5
 38000 -49.8 -57.6  275  71 37   7.2   4.0 | -49.8 -57.6  275  74 38   8.2   4.5
 36000 -45.5 -49.9  275  66 34   7.2   3.9 | -44.9 -48.8  270  67 34   8.2   4.5
 34000 -40.3 -40.5  270  59 31   8.8   4.8 | -39.5 -39.1  265  59 30   9.1   5.0
 32000 -35.0 -31.0  270  53 27   8.7   4.8 | -34.0 -29.2  260  51 26   9.0   4.9
 30000 -29.7 -21.5  260  45 23   7.8   4.3 | -28.7 -19.7  255  45 23   7.7   4.2
 29000 -27.3 -17.1  255  43 22   7.9   4.3 | -26.4 -15.5  250  43 22   7.7   4.2
 28000 -25.3 -13.5  250  39 20   4.0   2.2 | -24.4 -11.9  250  41 21   4.5   2.5
 27000 -24.0 -11.2  245  34 18   4.2   2.3 | -23.0  -9.4  245  38 20   4.7   2.6
 26000 -22.7  -8.9  240  29 15   4.3   2.3 | -21.6  -6.9  245  35 18   4.7   2.6
 25000 -21.5  -6.7  235  25 13   5.8   3.2 | -20.2  -4.4  245  33 17   4.7   2.6
 24000 -19.1  -2.4  240  22 12   8.0   4.4 | -18.8  -1.8  240  27 14   4.6   2.5
 23000 -16.7   1.9  245  20 11   8.0   4.4 | -17.5   0.5  235  22 11   4.6   2.5
 22000 -14.3   6.3  255  19 10   8.0   4.4 | -16.1   3.0  230  17  9   6.5   3.5
 21000 -11.9  10.6  255  16  8   7.9   4.4 | -13.7   7.3  235  16  8   8.0   4.4
 20000  -9.5  14.9  250  14  7   7.9   4.4 | -11.3  11.7  245  15  8   8.0   4.4
 19500  -8.3  17.1  250  13  6   7.8   4.3 | -10.1  13.8  245  15  8   8.4   4.6
 19000  -7.2  19.0  245  11  6   7.0   3.8 |  -8.5  16.7  250  15  8  12.0   6.6
 18500  -6.2  20.8  245  10  5   7.1   3.9 |  -6.7  19.9  250  14  7  11.8   6.5
 18000  -5.1  22.8  235   9  5   8.0   4.4 |  -5.0  23.0  255  14  7   9.2   5.0
 17500  -3.8  25.2  235   8  4   8.4   4.6 |  -3.9  25.0  255  12  6   8.3   4.5
 17000  -2.6  27.3  230   8  4   8.5   4.6 |  -2.7  27.1  260  10  5   8.4   4.6
 16500  -1.3  29.7  225   8  4   8.8   4.8 |  -1.5  29.3  260   9  5   8.9   4.9
 16000  -0.1  31.8  220   8  4   8.8   4.8 |  -0.2  31.6  260   8  4   8.9   4.9
 15500   1.2  34.2  220   7  4   9.1   5.0 |   1.1  34.0  260   7  4   8.6   4.7
 15000   3.2  37.8  215   7  3   9.1   5.0 |   3.0  37.4  260   6  3   8.7   4.7
 14500   4.6  40.3  215   6  3   9.3   5.1 |   4.3  39.7  265   5  3   8.3   4.6
 14000   5.9  42.6  220   6  3   9.3   5.1 |   5.5  41.9  270   4  2   8.3   4.6
 13500   7.3  45.1  220   5  3   9.0   5.0 |   6.8  44.2  280   3  1   8.3   4.6
 13000   8.6  47.5  225   4  2   9.0   4.9 |   8.1  46.6  310   2  1   8.3   4.5
 12500   9.9  49.8  235   3  2   9.1   5.0 |   9.3  48.7  355   2  1   8.4   4.6
 12000  11.2  52.2  250   3  1   8.8   4.9 |  10.5  50.9  005   4  2   8.1   4.5
 11750  11.9  53.4  255   3  1   8.7   4.8 |  11.2  52.2  010   5  3   8.1   4.4
 11500  12.6  54.7  265   3  1  10.0   5.5 |  11.8  53.2  010   6  3   8.6   4.7
 11250  13.3  55.9  280   2  1   9.5   5.2 |  12.4  54.3  010   7  4   8.4   4.6
 11000  13.9  57.0  295   3  1   8.0   4.4 |  13.0  55.4  010   8  4   7.9   4.3
 10750  14.6  58.3  305   3  2   8.3   4.5 |  13.6  56.5  010   8  4   7.9   4.3
 10500  15.2  59.4  310   3  2   8.7   4.7 |  14.2  57.6  005   9  5   8.7   4.8
 10250  15.9  60.6  315   4  2   9.2   5.0 |  14.9  58.8  005   9  5   9.4   5.2
 10000  16.5  61.7  320   4  2   8.2   4.5 |  15.5  59.9  005  10  5   9.3   5.1
  9750  17.1  62.8  320   4  2   7.4   4.1 |  16.2  61.2  005  10  5   9.3   5.1
  9500  17.7  63.9  325   5  2   8.0   4.4 |  16.9  62.4  360  10  5   9.8   5.4
  9250  18.3  64.9  325   5  3   8.3   4.5 |  17.7  63.9  360  10  5  10.3   5.6
  9000  18.9  66.0  325   5  3   8.1   4.4 |  18.4  65.1  360  10  5  10.0   5.5
  8750  19.5  67.1  330   6  3   7.4   4.1 |  19.2  66.6  360  10  5   9.6   5.2
  8500  20.0  68.0  330   6  3   5.0   2.8 |  19.9  67.8  360  10  5  10.3   5.7
  8250  20.2  68.4  325   7  4   3.1   1.7 |  20.7  69.3  360  10  5  11.1   6.1
  8000  20.5  68.9  320   8  4   5.3   2.9 |  21.5  70.7  360  10  5  10.8   5.9
  7750  20.8  69.4  320   9  5  -1.3  -0.7 |  22.3  72.1  360   9  5  11.3   6.2
  7500  20.2  68.4  310  10  5  -5.2  -2.9 |  23.2  73.8  360   9  5  11.0   6.1
  7250  20.0  68.0  310   9  5  -0.6  -0.3 |  23.9  75.0  360   9  5  10.2   5.6
  7000  19.8  67.6  305   8  4  -4.5  -2.5 |  24.7  76.5  360   9  5  10.9   6.0
  6750     M     M    M   M  M     M     M |     M     M    M   M  M     M     M

           09/20/2016 at 1400 MST          |       09/20/2016 at 1700 MST
                                           |
K index... +15.3  LI... +273.7             | K index... +17.3  LI... +273.2
CAPE... 0.0  CIN... -0.5                   | CAPE... 0.0  CIN... -9.3
                                           |
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 -67.3 -89.1  275  44 23   1.9   1.1 | -67.7 -89.9  275  47 24   1.9   1.0
 45000 -62.9 -81.2  275  60 31   4.7   2.6 | -63.0 -81.4  275  66 34   5.5   3.0
 40000 -54.8 -66.6  270  68 35   9.3   5.1 | -54.1 -65.4  275  78 40   8.7   4.8
 38000 -49.2 -56.6  265  63 32   9.3   5.1 | -48.8 -55.8  270  70 36   8.7   4.8
 36000 -43.6 -46.5  260  59 30   9.2   5.1 | -43.6 -46.5  265  61 32   8.7   4.8
 34000 -38.4 -37.1  260  54 28   8.7   4.8 | -38.5 -37.3  265  53 27   8.6   4.7
 32000 -33.1 -27.6  260  50 26   8.6   4.7 | -33.3 -27.9  270  45 23   8.5   4.7
 30000 -27.8 -18.0  265  47 24   7.7   4.2 | -28.2 -18.8  260  39 20   7.6   4.1
 29000 -25.5 -13.9  265  46 24   7.8   4.3 | -25.9 -14.6  260  37 19   7.6   4.2
 28000 -23.4 -10.1  265  45 23   5.3   2.9 | -23.8 -10.8  255  35 18   6.2   3.4
 27000 -21.8  -7.2  265  42 21   5.4   3.0 | -21.9  -7.4  260  34 17   6.3   3.4
 26000 -20.2  -4.4  265  38 20   5.4   3.0 | -20.1  -4.2  265  32 17   6.3   3.4
 25000 -18.6  -1.5  265  35 18   4.8   2.6 | -18.2  -0.8  270  31 16   5.9   3.2
 24000 -17.5   0.5  255  33 17   3.5   1.9 | -16.7   1.9  270  29 15   5.1   2.8
 23000 -16.5   2.3  240  33 17   3.5   1.9 | -15.2   4.6  265  28 14   5.1   2.8
 22000 -15.4   4.3  230  34 18   5.4   2.9 | -13.7   7.3  255  26 14   5.0   2.8
 21000 -13.3   8.1  230  27 14   7.3   4.0 | -12.3   9.9  250  22 11   5.0   2.7
 20000 -11.1  12.0  230  19 10   7.3   4.0 | -10.8  12.6  240  18  9   5.0   2.7
 19500 -10.1  13.8  230  15  8   7.4   4.0 | -10.1  13.8  235  16  8   4.8   2.6
 19000  -8.9  16.0  230  13  7   8.3   4.6 |  -9.1  15.6  230  14  7   8.8   4.8
 18500  -7.7  18.1  230  11  6   8.3   4.5 |  -7.9  17.8  225  13  7   8.4   4.6
 18000  -6.4  20.5  225   9  5   9.1   5.0 |  -6.6  20.1  220  12  6   8.5   4.7
 17500  -5.0  23.0  230   8  4   9.6   5.3 |  -5.3  22.5  220  11  6   8.7   4.8
 17000  -3.5  25.7  230   7  4   9.6   5.3 |  -4.0  24.8  215  10  5   8.7   4.8
 16500  -2.1  28.2  230   6  3   9.5   5.2 |  -2.6  27.3  210   9  5  10.1   5.5
 16000  -0.7  30.7  235   5  3   9.5   5.2 |  -1.1  30.0  205   8  4  10.0   5.5
 15500   0.7  33.3  235   5  2   9.1   5.0 |   0.4  32.7  200   7  4   9.5   5.2
 15000   2.7  36.9  230   3  2   9.1   5.0 |   2.5  36.5  190   6  3   9.5   5.2
 14500   4.0  39.2  225   2  1   8.5   4.7 |   3.9  39.0  180   5  2   9.1   5.0
 14000   5.3  41.5  215   2  1   8.6   4.7 |   5.2  41.4  170   4  2   9.2   5.0
 13500   6.6  43.9  185   1  0   8.4   4.6 |   6.6  43.9  155   4  2   9.3   5.1
 13000   7.8  46.0  050   1  1   8.6   4.7 |   8.0  46.4  150   3  2   9.2   5.0
 12500   9.0  48.2  035   3  2   8.6   4.7 |   9.5  49.1  135   3  2   9.9   5.4
 12000  10.4  50.7  035   4  2   9.6   5.3 |  10.8  51.4  130   3  1   9.2   5.0
 11750  11.1  52.0  035   4  2   9.6   5.2 |  11.5  52.7  125   3  1   8.7   4.8
 11500  11.9  53.4  030   5  2  10.5   5.7 |  12.2  54.0  120   3  1  10.2   5.6
 11250  12.7  54.9  030   5  2  10.1   5.5 |  13.0  55.4  120   3  1  10.0   5.5
 11000  13.3  55.9  030   5  2   9.1   5.0 |  13.6  56.5  115   3  1   8.3   4.6
 10750  14.0  57.2  030   5  2   9.2   5.0 |  14.3  57.7  110   3  1   8.6   4.7
 10500  14.7  58.5  035   5  2   9.9   5.4 |  14.9  58.8  105   3  1   9.3   5.1
 10250  15.5  59.9  030   5  2  10.7   5.9 |  15.7  60.3  110   3  1  10.3   5.7
 10000  16.3  61.3  030   5  2   9.9   5.4 |  16.4  61.5  110   2  1   9.0   5.0
  9750  17.0  62.6  030   5  2   9.5   5.2 |  17.0  62.6  105   2  1   8.2   4.5
  9500  17.7  63.9  030   5  2   9.5   5.2 |  17.7  63.9  100   2  1   8.5   4.7
  9250  18.4  65.1  030   5  2   9.4   5.2 |  18.3  64.9  105   2  1   8.5   4.6
  9000  19.1  66.4  030   5  2   9.7   5.3 |  18.9  66.0  110   2  1   8.8   4.8
  8750  19.9  67.8  030   5  2  10.4   5.7 |  19.6  67.3  115   2  1   9.8   5.4
  8500  20.7  69.3  030   5  2  10.5   5.8 |  20.4  68.7  115   2  1  10.0   5.5
  8250  21.5  70.7  030   4  2  10.3   5.7 |  21.1  70.0  125   2  1   9.5   5.2
  8000  22.2  72.0  030   4  2  10.3   5.6 |  21.8  71.2  135   2  1  10.0   5.5
  7750  23.0  73.4  030   4  2  10.7   5.9 |  22.5  72.5  145   2  1   8.7   4.8
  7500  23.8  74.8  030   4  2  10.3   5.7 |  23.0  73.4  145   2  1   5.3   2.9
  7250  24.5  76.1  030   4  2   9.5   5.2 |  23.3  73.9  145   2  1   3.9   2.2
  7000  25.2  77.4  030   4  2  10.2   5.6 |  23.5  74.3  145   2  1   5.0   2.7
  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) 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 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.