Soaring Guidance
Issued by NWS Pueblo, CO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12
430
UXUS97 KPUB 171307
SRGPUB

Soaring Forecast
National Weather Service Pueblo, Colorado
0606 MST Saturday, February 17, 2018

This forecast is for Saturday, February 17, 2018:

If the trigger temperature of 40.4 F/4.6 C is reached...then
   Thermal Soaring Index....................... Good
   Maximum rate of lift........................ 401 ft/min (2.0 m/s)
   Maximum height of thermals.................. 13066 ft MSL (5463 ft AGL)

Forecast maximum temperature................... 48.0 F/9.3 C
Time of trigger temperature.................... 1030 MST
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................. 11962 ft MSL (4358 ft AGL)
Thermal soaring outlook for Sunday 02/18....... Good

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

Remarks...

Sunrise/Sunset.................... 06:47:45 / 17:38:46 MST
Total possible sunshine........... 10 hr 51 min 1 sec (651 min 1 sec)
Altitude of sun at 12:13:16 MST... 39.13 degrees

Upper air data from numerical model forecast valid on 02/17/2018 at 0500 MST

Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 19726 ft MSL (12123 ft AGL)
Lifted condensation level....... 17600 ft MSL (9996 ft AGL)
Lifted index.................... +4.2
K index......................... -32.2

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  -62.2 -80.0   265   53   27   2.1   1.2      M     M       M      M    M
 45000  -59.1 -74.4   265   55   29   2.1   1.1      M     M       M      M    M
 40000  -59.8 -75.6   265   47   24  -0.9  -0.5      M     M       M      M    M
 38000  -59.6 -75.3   265   43   22   3.3   1.8      M     M       M      M    M
 36000  -57.6 -71.7   275   38   20   3.3   1.8      M     M       M      M    M
 34000  -55.6 -68.1   280   34   17   4.8   2.6      M     M       M      M    M
 32000  -51.8 -61.2   295   34   17   6.2   3.4      M     M       M      M    M
 30000  -48.1 -54.6   305   35   18   7.4   4.1   20.5  68.9     8.9      M    M
 29000  -45.7 -50.3   305   35   18   7.9   4.4   19.6  67.4     8.4      M    M
 28000  -43.3 -45.9   305   34   18   7.9   4.4   18.9  66.1     7.9      M    M
 27000  -40.9 -41.6   305   34   17   7.9   4.4   18.4  65.0     7.5      M    M
 26000  -38.5 -37.3   305   33   17   8.0   4.4   17.7  63.8     7.1      M    M
 25000  -36.1 -33.0   300   33   17   8.0   4.4   17.0  62.6     6.6      M    M
 24000  -33.7 -28.7   300   32   17   8.0   4.4   16.4  61.6     6.2      M    M
 23000  -31.1 -24.0   295   32   17   8.9   4.9   16.0  60.8     5.9      M    M
 22000  -27.8 -18.0   290   32   17   9.0   4.9   15.6  60.1     5.7      M    M
 21000  -25.1 -13.2   285   33   17   9.0   4.9   15.4  59.8     5.6      M    M
 20000  -22.4  -8.3   285   33   17   9.0   5.0   15.1  59.2     5.4      M    M
 19500  -21.0  -5.8   285   34   17   9.0   5.0   15.0  58.9     5.3      M    M
 19000  -19.7  -3.5   285   34   17   9.0   4.9   14.9  58.8     5.3      M    M
 18500  -18.3  -0.9   285   34   17   8.7   4.8   14.8  58.6     5.2      M    M
 18000  -17.1   1.2   285   34   17   8.0   4.4   14.5  58.1     5.0      M    M
 17500  -15.9   3.4   290   33   17   8.1   4.5   14.2  57.6     4.8      M    M
 17000  -14.7   5.5   290   32   16   7.0   3.8   13.9  57.0     4.5      M    M
 16500  -13.7   7.3   290   30   16   7.0   3.9   13.4  56.2     4.1      M    M
 16000  -12.6   9.3   295   28   15   7.3   4.0   13.0  55.4     3.7      M    M
 15500  -11.5  11.3   295   26   14   7.5   4.1   12.6  54.7     3.4      M    M
 15000  -10.3  13.5   300   24   13   7.0   3.8   12.3  54.1     3.1      M    M
 14500   -9.5  14.9   300   25   13   5.2   2.9   11.6  52.9     2.5      M    M
 14000   -8.7  16.3   300   26   14   5.3   2.9   10.9  51.6     1.9      M    M
 13500   -8.1  17.4   300   26   14   2.5   1.4    9.9  49.9     1.0      M    M
 13000   -7.7  18.1   305   26   13   3.0   1.7    8.8  47.9    -0.1    399  2.0
 12500   -7.5  18.5   300   25   13   0.0   0.0    7.5  45.5    -1.3    378  1.9
 12000   -7.5  18.5   300   26   13   0.4   0.2    6.0  42.8    -2.8    362  1.8
 11750   -7.4  18.7   300   26   13   0.5   0.3    5.3  41.5    -3.5    354  1.8
 11500   -7.4  18.7   300   25   13  -0.1  -0.1    4.6  40.2    -4.2    346  1.8
 11250   -7.5  18.5   300   24   12  -1.9  -1.0    3.7  38.7    -5.1    342  1.7
 11000   -7.8  18.0   300   23   12  -4.0  -2.2    2.7  36.9    -6.1    342  1.7
 10750   -8.0  17.6   300   23   12   1.1   0.6    1.8  35.2    -7.1    342  1.7
 10500   -7.7  18.1   300   21   11   5.7   3.1    1.4  34.5    -7.5    325  1.6
 10250   -7.4  18.7   300   20   10   4.2   2.3    1.0  33.8    -7.9    307  1.6
 10000   -7.1  19.2   300   18    9   4.3   2.4    0.6  33.0    -8.4    291  1.5
  9750   -6.7  19.9   300   17    9   6.5   3.5    0.2  32.3    -8.8    273  1.4
  9500   -6.1  21.0   300   15    8   7.7   4.2    0.0  32.0    -9.0    248  1.3
  9250   -5.6  21.9   305   14    7   8.1   4.5   -0.1  31.7    -9.2    224  1.1
  9000   -4.9  23.2   305   13    7   9.1   5.0   -0.2  31.6    -9.3    197  1.0
  8750   -4.3  24.3   310   11    6   8.0   4.4   -0.3  31.5    -9.4    170  0.9
  8500   -3.7  25.3   310   10    5   5.9   3.2   -0.5  31.1    -9.6    147  0.7
  8250   -3.2  26.2   315    9    5  10.7   5.9   -0.7  30.7    -9.8    124  0.6
  8000   -2.4  27.7   325    7    4   3.2   1.8   -0.7  30.8    -9.8     93  0.5
  7750   -3.2  26.2   325    5    3 -22.4 -12.3   -2.2  28.1   -11.3    109  0.6
  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 * * * * * *

           02/17/2018 at 0800 MST          |       02/17/2018 at 1100 MST
                                           |
CAPE...     0.0    LI...       +4.9        | CAPE...     0.0    LI...       +6.6
CINH...     0.0    K Index... -23.7        | CINH...     0.0    K Index... -18.5
                                           |
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 -63.2 -81.8  265  52 27   1.0   0.5 | -65.2 -85.4  265  53 27   0.3   0.2
 45000 -61.7 -79.1  270  53 27   1.0   0.5 | -64.7 -84.5  265  54 28   0.3   0.2
 40000 -61.1 -78.0  275  46 24   0.3   0.2 | -62.9 -81.2  285  42 22   1.3   0.7
 38000 -60.3 -76.5  280  42 22   3.3   1.8 | -61.2 -78.2  290  39 20   4.8   2.6
 36000 -58.3 -72.9  285  38 19   3.3   1.8 | -58.3 -72.9  300  37 19   4.8   2.6
 34000 -56.2 -69.2  290  33 17   6.1   3.4 | -55.1 -67.2  305  37 19   8.2   4.5
 32000 -51.9 -61.4  295  33 17   7.2   4.0 | -50.5 -58.9  305  35 18   7.8   4.3
 30000 -47.5 -53.5  300  33 17   8.5   4.7 | -45.8 -50.4  305  33 17   8.2   4.5
 29000 -44.9 -48.8  305  34 17   8.6   4.7 | -43.3 -45.9  305  32 17   8.2   4.5
 28000 -42.3 -44.1  305  34 17   8.6   4.7 | -40.8 -41.4  300  32 16   8.2   4.5
 27000 -39.7 -39.5  305  34 18   8.6   4.7 | -38.4 -37.1  300  31 16   8.2   4.5
 26000 -37.1 -34.8  305  34 18   8.7   4.7 | -35.9 -32.6  300  31 16   8.2   4.5
 25000 -34.5 -30.1  300  34 17   8.7   4.7 | -33.4 -28.1  300  30 16   8.2   4.5
 24000 -31.9 -25.4  300  34 17   8.7   4.8 | -31.0 -23.8  300  30 15   8.1   4.5
 23000 -28.8 -19.8  300  34 17   8.0   4.4 | -27.7 -17.9  300  28 14   9.0   4.9
 22000 -26.4 -15.5  295  34 17   8.1   4.4 | -25.0 -13.0  295  26 14   9.0   4.9
 21000 -24.0 -11.2  295  34 17   7.8   4.3 | -22.3  -8.1  295  25 13   7.9   4.3
 20000 -21.7  -7.1  295  34 18   7.6   4.2 | -20.0  -4.0  295  25 13   7.8   4.3
 19500 -20.6  -5.1  295  34 18   7.6   4.2 | -18.8  -1.8  295  24 13   7.8   4.3
 19000 -19.5  -3.1  295  35 18   7.6   4.2 | -17.7   0.1  295  24 12   7.8   4.3
 18500 -18.3  -0.9  295  35 18   7.7   4.2 | -16.5   2.3  295  24 12   7.1   3.9
 18000 -17.2   1.0  295  35 18   7.7   4.2 | -15.5   4.1  300  26 13   6.8   3.7
 17500 -16.0   3.2  295  35 18   7.8   4.3 | -14.5   5.9  300  28 14   6.7   3.7
 17000 -14.9   5.2  295  35 18   7.2   3.9 | -13.7   7.3  300  29 15   5.0   2.8
 16500 -13.8   7.2  295  35 18   7.3   4.0 | -12.9   8.8  300  29 15   5.2   2.9
 16000 -12.8   9.0  295  34 18   6.4   3.5 | -12.2  10.0  300  29 15   4.6   2.5
 15500 -11.8  10.8  300  33 17   6.0   3.3 | -11.5  11.3  300  29 15   4.5   2.5
 15000 -10.9  12.4  300  32 16   5.2   2.8 | -10.8  12.6  300  28 15   3.9   2.1
 14500 -10.3  13.5  300  30 16   3.7   2.0 | -10.3  13.5  305  28 14   3.3   1.8
 14000  -9.8  14.4  300  29 15   3.5   1.9 |  -9.8  14.4  305  27 14   3.1   1.7
 13500  -9.4  15.1  300  26 14   2.0   1.1 |  -9.4  15.1  305  25 13   2.6   1.4
 13000  -9.1  15.6  300  23 12   2.1   1.2 |  -9.0  15.8  305  24 12   2.8   1.5
 12500  -8.6  16.5  300  22 11   3.3   1.8 |  -8.5  16.7  305  22 11   2.8   1.5
 12000  -8.2  17.2  300  19 10   2.8   1.6 |  -8.2  17.2  305  18  9   2.1   1.1
 11750  -8.0  17.6  300  17  9   2.7   1.5 |  -8.1  17.4  305  16  8   2.5   1.4
 11500  -7.8  18.0  300  17  9   2.6   1.5 |  -7.9  17.8  300  15  8   2.6   1.4
 11250  -7.6  18.3  300  16  8   2.3   1.3 |  -7.7  18.1  300  14  7   2.2   1.2
 11000  -7.5  18.5  305  16  8   2.2   1.2 |  -7.6  18.3  295  11  6   2.2   1.2
 10750  -7.3  18.9  305  15  8   2.3   1.3 |  -7.4  18.7  290  10  5   3.0   1.6
 10500  -7.2  19.0  305  14  7   3.1   1.7 |  -7.2  19.0  285   8  4   2.4   1.3
 10250  -7.0  19.4  300  13  7   0.7   0.4 |  -7.0  19.4  280   7  4   5.2   2.8
 10000  -7.1  19.2  300  12  6  -0.6  -0.4 |  -6.5  20.3  270   6  3   7.7   4.2
  9750  -7.0  19.4  295  11  6   3.3   1.8 |  -6.0  21.2  260   4  2   6.6   3.6
  9500  -6.7  19.9  295  10  5   4.9   2.7 |  -5.5  22.1  240   3  2   5.9   3.2
  9250  -6.4  20.5  295   8  4   4.1   2.3 |  -5.0  23.0  215   3  2   8.5   4.7
  9000  -6.0  21.2  290   7  3   6.5   3.6 |  -4.3  24.3  185   3  1  10.4   5.7
  8750  -5.4  22.3  290   5  3   8.6   4.7 |  -3.6  25.5  175   3  2   9.2   5.1
  8500  -4.8  23.4  285   4  2   9.0   4.9 |  -2.9  26.8  170   3  2   9.4   5.2
  8250  -4.1  24.6  280   2  1   6.3   3.5 |  -2.2  28.0  160   3  2   9.9   5.4
  8000  -3.9  25.0  275   1  1   2.9   1.6 |  -1.3  29.7  160   4  2  14.5   8.0
  7750  -3.6  25.5  275   1  1   5.6   3.1 |   0.0  32.0  155   4  2  20.5  11.2
  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

           02/17/2018 at 1400 MST          |       02/17/2018 at 1700 MST
                                           |
CAPE...     0.0    LI...       +7.9        | CAPE...     0.0    LI...       +6.6
CINH...     0.0    K Index... -10.6        | CINH...     0.0    K Index...  -9.9
                                           |
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 -67.2 -89.0  270  54 28  -0.8  -0.4 | -68.4 -91.1  270  52 27  -0.3  -0.1
 45000 -68.4 -91.1  270  52 27  -0.8  -0.4 | -68.8 -91.8  270  48 25  -0.3  -0.2
 40000 -65.1 -85.2  280  38 19   2.4   1.3 | -64.9 -84.8  270  37 19   2.7   1.5
 38000 -62.1 -79.8  290  34 18   6.9   3.8 | -61.8 -79.2  270  34 17   7.2   3.9
 36000 -58.0 -72.4  290  34 18   6.9   3.8 | -57.5 -71.5  275  33 17   7.2   3.9
 34000 -53.7 -64.7  295  34 18   8.2   4.5 | -53.0 -63.4  275  32 17   8.4   4.6
 32000 -48.8 -55.8  295  32 17   8.2   4.5 | -47.9 -54.2  275  32 16   8.4   4.6
 30000 -43.9 -47.0  290  31 16   7.8   4.3 | -42.8 -45.0  280  32 16   8.4   4.6
 29000 -41.6 -42.9  290  31 16   7.8   4.3 | -40.3 -40.5  280  31 16   8.5   4.6
 28000 -39.2 -38.6  290  31 16   7.8   4.3 | -37.8 -36.0  280  31 16   8.5   4.6
 27000 -36.9 -34.4  285  30 16   7.9   4.4 | -35.2 -31.4  280  31 16   8.3   4.5
 26000 -34.4 -29.9  285  30 15   8.2   4.5 | -32.8 -27.0  280  30 16   8.1   4.4
 25000 -32.0 -25.6  290  30 15   8.2   4.5 | -30.4 -22.7  280  30 15   8.1   4.4
 24000 -29.5 -21.1  290  29 15   8.2   4.5 | -28.0 -18.4  280  29 15   8.1   4.4
 23000 -26.3 -15.3  285  27 14   8.7   4.8 | -24.9 -12.8  280  26 14   8.1   4.5
 22000 -23.7 -10.7  285  25 13   8.7   4.8 | -22.5  -8.5  280  24 12   8.2   4.5
 21000 -21.1  -6.0  280  23 12   7.4   4.1 | -20.1  -4.2  280  22 11   7.3   4.0
 20000 -18.9  -2.0  290  25 13   7.4   4.1 | -17.9  -0.2  285  24 13   7.3   4.0
 19500 -17.8  -0.0  290  26 13   7.4   4.1 | -16.8   1.8  285  26 13   7.3   4.0
 19000 -16.7   1.9  295  27 14   7.5   4.1 | -15.7   3.7  290  27 14   7.4   4.1
 18500 -15.6   3.9  295  28 14   6.8   3.7 | -14.7   5.5  290  27 14   6.1   3.3
 18000 -14.7   5.5  295  27 14   6.5   3.6 | -13.8   7.2  290  26 13   5.7   3.1
 17500 -13.7   7.3  295  27 14   6.3   3.4 | -13.0   8.6  290  24 12   5.6   3.1
 17000 -12.9   8.8  295  27 14   4.6   2.5 | -12.2  10.0  290  23 12   5.1   2.8
 16500 -12.2  10.0  300  27 14   4.9   2.7 | -11.5  11.3  290  23 12   5.2   2.8
 16000 -11.7  10.9  300  27 14   2.5   1.3 | -10.7  12.7  290  24 12   4.7   2.6
 15500 -11.3  11.7  300  27 14   2.3   1.3 | -10.0  14.0  290  24 12   4.7   2.6
 15000 -11.0  12.2  300  26 14   2.0   1.1 |  -9.4  15.1  285  23 12   4.2   2.3
 14500 -10.7  12.7  295  25 13   1.9   1.0 |  -8.8  16.2  285  23 12   3.9   2.1
 14000 -10.5  13.1  295  23 12   3.2   1.8 |  -8.2  17.2  285  22 11   3.9   2.1
 13500  -9.7  14.5  290  20 10   5.7   3.1 |  -7.6  18.3  280  20 10   4.0   2.2
 13000  -8.8  16.2  280  17  9   6.8   3.7 |  -7.0  19.4  275  17  9   4.8   2.6
 12500  -7.6  18.3  275  15  8   8.5   4.7 |  -6.1  21.0  270  16  8   5.8   3.2
 12000  -6.4  20.5  265  13  7   7.5   4.1 |  -5.4  22.3  255  14  7   5.6   3.0
 11750  -5.9  21.4  260  12  6   5.6   3.1 |  -4.9  23.2  250  14  7   6.8   3.7
 11500  -5.5  22.1  255  11  6   5.7   3.1 |  -4.4  24.1  245  14  7   7.3   4.0
 11250  -5.0  23.0  250  11  6   8.1   4.4 |  -3.9  25.0  245  14  7   7.2   4.0
 11000  -4.4  24.1  250  10  5   6.8   3.7 |  -3.3  26.1  240  14  7   6.9   3.8
 10750  -4.1  24.6  245  10  5   3.3   1.8 |  -2.9  26.8  235  14  7   6.4   3.5
 10500  -3.9  25.0  235  10  5   1.4   0.8 |  -2.4  27.7  235  14  7   5.3   2.9
 10250  -3.8  25.2  230   9  5   5.5   3.0 |  -2.0  28.4  230  14  7   8.3   4.5
 10000  -3.2  26.2  225   9  5   6.9   3.8 |  -1.3  29.7  225  14  7   8.7   4.8
  9750  -2.9  26.8  215   9  5   3.6   2.0 |  -0.8  30.6  225  14  7   4.8   2.7
  9500  -2.6  27.3  210   9  5   2.9   1.6 |  -0.5  31.1  220  14  7   3.6   2.0
  9250  -2.4  27.7  200   9  5   5.5   3.0 |  -0.2  31.6  215  14  7   6.8   3.7
  9000  -1.8  28.8  195   9  5   8.8   4.8 |   0.4  32.7  215  14  7   7.7   4.2
  8750  -1.2  29.8  185   9  5   8.6   4.7 |   0.8  33.4  210  14  7   4.6   2.5
  8500  -0.5  31.1  180   9  5   8.5   4.7 |   1.2  34.2  205  13  7   5.5   3.0
  8250   0.1  32.2  175   9  5   8.9   4.9 |   1.6  34.9  200  13  7   2.9   1.6
  8000   0.9  33.6  170   9  4  13.5   7.4 |   1.6  34.9  195  12  6  -1.2  -0.6
  7750   2.1  35.8  170   8  4  19.6  10.7 |   1.5  34.7  190   9  5  -0.1  -0.1
  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.