Soaring Guidance
Issued by NWS Grand Junction, 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 13 14
000
UXUS97 KGJT 251306
SRGGJT

Soaring Forecast
National Weather Service Grand Junction, Colorado
0706 MDT Monday, September 25, 2017

This forecast is for Monday, September 25, 2017:

If the trigger temperature of 55.0 F/12.8 C is reached...then
   Thermal Soaring Index....................... Good
   Maximum rate of lift........................ 561 ft/min (2.8 m/s)
   Maximum height of thermals.................. 12371 ft MSL (7532 ft AGL)

Forecast maximum temperature................... 63.0 F/17.7 C
Time of trigger temperature.................... 1115 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................. 9536 ft MSL (4696 ft AGL)
Thermal soaring outlook for Tuesday 09/26...... Good

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

Remarks...

Sunrise/Sunset.................... 07:04:52 / 19:07:21 MDT
Total possible sunshine........... 12 hr 2 min 29 sec (722 min 29 sec)
Altitude of sun at 13:05:37 MDT... 49.74 degrees

Upper air data from rawinsonde observation taken on 09/25/2017 at 0600 MDT

Freezing level.................. 9511 ft MSL (4672 ft AGL)
Convective condensation level... 14190 ft MSL (9351 ft AGL)
Lifted condensation level....... 13413 ft MSL (8573 ft AGL)
Lifted index.................... +1.3
K index......................... +7.7

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  -56.9 -70.4   225   31   16   7.1   3.9  104.8 220.6    50.1      M    M
 45000  -52.4 -62.3   225   33   17   5.8   3.2   87.5 189.5    43.0      M    M
 40000  -47.5 -53.5   225   40   21  -0.7  -0.4   71.2 160.1    35.4      M    M
 38000  -46.6 -51.9   220   42   21   1.8   1.0   63.7 146.6    31.3      M    M
 36000  -44.9 -48.8   220   42   22   3.4   1.9   57.5 135.5    27.8      M    M
 34000  -42.7 -44.9   215   45   23   3.3   1.8   52.5 126.5    25.0      M    M
 32000  -43.1 -45.6   215   46   24   1.6   0.9   43.5 110.4    19.1      M    M
 30000  -44.3 -47.7   215   41   21  -7.7  -4.2   33.3  91.9    12.0      M    M
 29000  -43.5 -46.3   220   30   16   5.0   2.8   30.3  86.5     9.9      M    M
 28000  -42.0 -43.6   225   20   10   5.3   2.9   28.5  83.3     8.6      M    M
 27000  -39.9 -39.8   245   11    6   9.2   5.1   27.5  81.5     8.0      M    M
 26000  -37.1 -34.8   270   13    7   9.2   5.1   27.3  81.2     7.9      M    M
 25000  -34.4 -29.9   270   13    7   9.2   5.1   27.1  80.8     7.8      M    M
 24000  -31.6 -24.9   260   12    6   8.9   4.9   26.8  80.3     7.7      M    M
 23000  -29.1 -20.4   270   15    8   8.3   4.6   26.4  79.5     7.4      M    M
 22000  -26.6 -15.9   245   16    8   8.3   4.6   25.9  78.6     7.1      M    M
 21000  -24.2 -11.6   240   16    8   8.3   4.6   25.3  77.6     6.7      M    M
 20000  -21.7  -7.1   230   16    8   8.3   4.6   24.9  76.8     6.4      M    M
 19500  -20.5  -4.9   235   17    9   8.5   4.7   24.6  76.3     6.2      M    M
 19000  -19.4  -2.9   235   17    9   6.0   3.3   24.1  75.4     5.8      M    M
 18500  -18.5  -1.3   240   18    9   6.1   3.3   23.5  74.4     5.3      M    M
 18000  -17.6   0.3   235   19   10   5.8   3.2   22.9  73.2     4.8      M    M
 17500  -16.6   2.1   235   18    9   8.1   4.4   22.4  72.3     4.4      M    M
 17000  -15.4   4.3   240   17    9   7.9   4.4   22.0  71.7     4.1      M    M
 16500  -14.2   6.4   240   16    8   7.9   4.3   21.7  71.1     3.9      M    M
 16000  -12.4   9.7   245   14    7   7.9   4.3   21.3  70.4     3.5      M    M
 15500  -11.2  11.8   245   13    7   7.7   4.2   21.0  69.8     3.2      M    M
 15000  -10.2  13.6   245   12    6   6.8   3.7   20.5  69.0     2.8      M    M
 14500   -9.2  15.4   245   11    6   7.0   3.9   20.1  68.1     2.4      M    M
 14000   -8.0  17.6   245   10    5   8.1   4.5   19.7  67.5     2.1      M    M
 13500   -6.8  19.8   240    9    5   7.8   4.3   19.4  67.0     1.9      M    M
 13000   -5.8  21.6   230    9    4   6.5   3.6   18.9  66.1     1.4      M    M
 12500   -5.4  22.3   225    8    4  -4.0  -2.2   17.9  64.2     0.4      M    M
 12000   -5.5  22.1   215    8    4   7.7   4.2   16.3  61.3    -1.2    547  2.8
 11500   -4.3  24.3   220    8    4   7.4   4.0   16.0  60.8    -1.5    497  2.5
 11000   -3.5  25.7   230    8    4   6.5   3.6   15.4  59.7    -2.2    459  2.3
 10500   -2.3  27.9   235    8    4   8.2   4.5   15.1  59.2    -2.4    407  2.1
 10250   -1.7  28.9   240    8    4   8.3   4.5   15.0  59.0    -2.5    381  1.9
 10000   -1.1  30.0   240    7    4   8.5   4.7   14.9  58.8    -2.7    356  1.8
  9750   -0.5  31.1   240    6    3   7.9   4.3   14.8  58.6    -2.8    330  1.7
  9500    0.0  32.0   235    5    2   5.1   2.8   14.5  58.2    -3.0    308  1.6
  9250    0.3  32.5   235    3    2   3.7   2.0   14.1  57.4    -3.5    292  1.5
  9000    0.6  33.1   225    2    1   4.0   2.2   13.6  56.6    -3.9    276  1.4
  8750    0.9  33.6   245    1    1   4.0   2.2   13.2  55.7    -4.4    261  1.3
  8500    1.1  34.0   275    1    1   3.8   2.1   12.7  54.9    -4.9    245  1.2
  8250    1.5  34.7   315    1    1   5.9   3.2   12.3  54.2    -5.3    228  1.2
  8000    2.0  35.6   335    2    1   7.7   4.2   12.1  53.9    -5.5    204  1.0
  7750    2.5  36.5   325    2    1   7.2   4.0   12.0  53.5    -5.7    181  0.9
  7500    3.1  37.6   315    2    1   7.3   4.0   11.8  53.2    -5.9    157  0.8
  7250    3.6  38.5   305    3    1   7.3   4.0   11.6  52.9    -6.1    133  0.7
  7000    4.2  39.6   300    3    2   7.3   4.0   11.4  52.5    -6.3    110  0.6
  6750    4.7  40.5   315    3    1   7.3   4.0   11.2  52.2    -6.5     86  0.4
  6500    5.2  41.4   330    3    2   7.3   4.0   11.0  51.9    -6.7     63  0.3
  6250    5.8  42.4   345    3    2   7.2   4.0   10.8  51.5    -6.9     39  0.2
  6000    6.3  43.3   355    4    2   7.6   4.2   10.7  51.2    -7.1     16  0.1
  5750    6.8  44.2   005    3    2   4.6   2.5   10.4  50.8    -7.3      M    M
  5500    7.1  44.8   020    3    1   4.3   2.4    9.9  49.9    -7.9      M    M
  5250    7.3  45.1   040    2    1  -2.1  -1.2    9.5  49.0    -8.4      M    M
  5000    6.4  43.5   070    2    1 -23.8 -13.0    7.8  46.0   -10.1      M    M

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

           09/25/2017 at 0900 MDT          |       09/25/2017 at 1200 MDT
                                           |
K index... +12.4  LI... +2.8               | K index... +12.9  LI... +2.9
CAPE... 0.0  CIN... 0.0                    | CAPE... 0.0  CIN... 0.0
                                           |
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 -55.0 -67.0  235  25 13   2.2   1.2 | -55.0 -67.0  245  24 13   1.9   1.1
 45000 -51.5 -60.7  235  34 17   3.3   1.8 | -51.6 -60.9  245  32 17   3.7   2.1
 40000 -46.4 -51.5  235  40 20   3.2   1.8 | -46.0 -50.8  250  38 20   3.7   2.0
 38000 -45.1 -49.2  235  39 20   1.6   0.9 | -44.8 -48.6  250  36 19   1.1   0.6
 36000 -44.1 -47.4  230  38 19   1.6   0.9 | -44.1 -47.4  250  33 17   1.1   0.6
 34000 -43.4 -46.1  225  35 18  -0.9  -0.5 | -43.6 -46.5  250  29 15  -0.2  -0.1
 32000 -43.9 -47.0  230  30 16  -0.8  -0.4 | -43.6 -46.5  250  25 13  -0.1  -0.1
 30000 -44.0 -47.2  235  25 13   4.2   2.3 | -43.4 -46.1  255  22 11   4.2   2.3
 29000 -42.9 -45.2  235  23 12   3.8   2.1 | -41.9 -43.4  250  22 11   3.9   2.1
 28000 -41.5 -42.7  235  20 10   3.8   2.1 | -40.8 -41.4  245  22 11   3.9   2.1
 27000 -40.2 -40.4  240  17  9   7.5   4.1 | -39.5 -39.1  245  22 11   6.8   3.7
 26000 -37.5 -35.5  240  16  8   9.0   5.0 | -37.1 -34.8  240  22 11   8.1   4.4
 25000 -34.8 -30.6  250  15  8   9.1   5.0 | -34.6 -30.3  230  21 11   8.1   4.5
 24000 -32.1 -25.8  255  14  7   9.2   5.1 | -32.2 -26.0  225  21 11   8.6   4.7
 23000 -29.3 -20.7  255  14  7   9.4   5.2 | -29.5 -21.1  230  20 10   9.1   5.0
 22000 -26.5 -15.7  255  14  7   9.4   5.2 | -26.8 -16.2  235  19 10   9.1   5.0
 21000 -23.8 -10.8  255  14  7   7.8   4.3 | -24.1 -11.4  240  18  9   8.5   4.7
 20000 -21.5  -6.7  250  14  7   7.7   4.2 | -21.6  -6.9  245  17  9   8.5   4.7
 19500 -20.3  -4.5  250  14  7   7.7   4.2 | -20.3  -4.5  245  17  9   8.5   4.7
 19000 -19.2  -2.6  250  14  7   7.7   4.2 | -19.0  -2.2  245  17  9   8.5   4.7
 18500 -18.1  -0.6  250  14  7   7.4   4.1 | -17.8  -0.0  245  16  8   8.0   4.4
 18000 -17.0   1.4  245  14  7   7.3   4.0 | -16.7   1.9  245  16  8   7.7   4.3
 17500 -15.9   3.4  240  14  7   7.3   4.0 | -15.5   4.1  240  16  8   7.6   4.2
 17000 -14.8   5.4  240  14  7   7.4   4.1 | -14.4   6.1  240  15  8   7.0   3.9
 16500 -13.7   7.3  240  13  7   7.5   4.1 | -13.4   7.9  240  15  8   7.1   3.9
 16000 -12.6   9.3  240  13  7   6.7   3.7 | -12.4   9.7  240  14  7   6.6   3.6
 15500 -11.6  11.1  245  13  7   6.7   3.7 | -11.4  11.5  245  14  7   6.6   3.6
 15000 -10.6  12.9  245  12  6   6.1   3.4 | -10.4  13.3  245  13  7   6.1   3.4
 14500  -9.8  14.4  245  12  6   5.8   3.2 |  -9.6  14.7  240  12  6   5.8   3.2
 14000  -9.0  15.8  250  12  6   5.5   3.0 |  -8.3  17.1  240  11  6   5.7   3.1
 13500  -7.9  17.8  250  11  6   5.0   2.7 |  -7.5  18.5  235  10  5   5.6   3.1
 13000  -7.1  19.2  255  10  5   5.9   3.3 |  -6.6  20.1  235   9  5   6.3   3.4
 12500  -6.3  20.7  255  10  5   6.0   3.3 |  -5.7  21.7  230   9  4   6.4   3.5
 12000  -5.4  22.3  260   9  5   6.8   3.7 |  -4.8  23.4  230   8  4   6.9   3.8
 11500  -4.4  24.1  260   8  4   7.0   3.8 |  -3.8  25.2  225   6  3   7.0   3.8
 11000  -3.3  26.1  265   7  4   7.4   4.0 |  -2.7  27.1  220   5  3   7.2   3.9
 10500  -2.3  27.9  265   6  3   8.3   4.5 |  -1.7  28.9  215   4  2   7.7   4.2
 10250  -1.7  28.9  265   5  2   4.1   2.3 |  -1.2  29.8  205   3  2   5.2   2.9
 10000  -1.6  29.1  260   4  2   4.9   2.7 |  -0.9  30.4  200   3  1   6.1   3.4
  9750  -0.9  30.4  255   3  2   9.5   5.2 |  -0.2  31.6  195   2  1   9.2   5.0
  9500  -0.3  31.5  245   2  1   8.8   4.8 |   0.4  32.7  185   2  1   8.8   4.8
  9250   0.3  32.5  225   2  1   7.0   3.9 |   1.0  33.8  170   2  1   7.4   4.1
  9000   0.7  33.3  220   1  1   5.1   2.8 |   1.5  34.7  170   1  1   7.1   3.9
  8750   1.1  34.0  215   1  0   6.0   3.3 |   2.1  35.8  165   1  0   8.5   4.7
  8500   1.6  34.9  000   0  0   5.8   3.2 |   2.7  36.9  000   0  0   8.0   4.4
  8250   2.0  35.6  050   1  0   6.0   3.3 |   3.3  37.9  350   1  0   7.6   4.2
  8000   2.5  36.5  050   1  1   5.5   3.0 |   3.8  38.8  330   1  0   6.9   3.8
  7750   2.8  37.0  050   2  1   4.6   2.5 |   4.3  39.7  330   1  1   6.1   3.3
  7500   3.2  37.8  050   2  1   4.1   2.3 |   4.8  40.6  330   2  1   7.5   4.1
  7250   3.5  38.3  050   3  1   4.0   2.2 |   5.5  41.9  325   2  1  10.0   5.5
  7000   3.8  38.8  055   3  1   3.9   2.2 |   6.2  43.2  325   2  1  10.0   5.5
  6750   4.1  39.4  055   3  2   3.7   2.0 |   7.0  44.6  320   2  1   9.7   5.3
  6500   4.4  39.9  060   3  2   3.0   1.7 |   7.7  45.9  320   2  1  10.6   5.8
  6250   4.6  40.3  065   3  2   3.2   1.8 |   8.5  47.3  315   2  1  11.9   6.5
  6000   4.8  40.6  070   3  2   1.7   0.9 |   9.4  48.9  310   2  1   9.6   5.3
  5750   5.0  41.0  080   3  2   5.1   2.8 |  10.1  50.2  310   2  1  11.0   6.1
  5500   5.6  42.1  080   3  2  10.2   5.6 |  11.1  52.0  310   2  1  15.6   8.6
  5250   6.3  43.3  080   3  2   6.4   3.5 |  12.2  54.0  310   2  1  13.8   7.5
  5000     M     M    M   M  M     M     M |     M     M    M   M  M     M     M

           09/25/2017 at 1500 MDT          |       09/25/2017 at 1800 MDT
                                           |
K index... +12.9  LI... +1.3               | K index... +10.0  LI... -0.2
CAPE... +0.2  CIN... -0.4                  | CAPE... +29.6  CIN... -6.7
                                           |
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 -55.2 -67.4  245  26 13   1.8   1.0 | -55.8 -68.4  245  24 12   2.0   1.1
 45000 -52.3 -62.1  245  33 17   3.4   1.9 | -52.6 -62.7  245  33 17   2.2   1.2
 40000 -47.0 -52.6  255  38 19   3.3   1.8 | -49.3 -56.7  255  38 19   2.1   1.2
 38000 -46.0 -50.8  260  40 20   0.8   0.4 | -48.8 -55.8  260  43 22   0.3   0.1
 36000 -45.5 -49.9  260  42 21   0.8   0.4 | -48.7 -55.7  265  51 26   0.3   0.1
 34000 -44.8 -48.6  265  42 22   2.6   1.4 | -47.4 -53.3  270  56 29   6.7   3.7
 32000 -43.3 -45.9  265  38 20   2.6   1.4 | -43.3 -45.9  270  56 29   6.8   3.7
 30000 -41.6 -42.9  270  34 17   4.1   2.3 | -39.3 -38.7  270  54 28   6.3   3.4
 29000 -40.1 -40.2  265  32 16   4.1   2.2 | -36.9 -34.4  275  52 27   6.3   3.4
 28000 -38.8 -37.8  265  30 16   4.0   2.2 | -35.1 -31.2  275  50 26   6.3   3.4
 27000 -37.5 -35.5  260  29 15   6.4   3.5 | -33.3 -27.9  275  47 24   4.9   2.7
 26000 -35.4 -31.7  255  28 14   7.0   3.8 | -31.8 -25.2  275  43 22   4.9   2.7
 25000 -33.3 -27.9  250  27 14   7.0   3.8 | -30.3 -22.5  275  38 20   4.9   2.7
 24000 -31.3 -24.3  245  26 13   7.5   4.1 | -28.8 -19.8  275  34 17   6.0   3.3
 23000 -28.9 -20.0  245  25 13   7.9   4.4 | -26.9 -16.4  270  30 16   6.5   3.6
 22000 -26.5 -15.7  240  24 12   7.9   4.4 | -24.9 -12.8  270  27 14   6.5   3.6
 21000 -24.1 -11.4  235  24 12   8.2   4.5 | -22.9  -9.2  265  24 12   7.4   4.1
 20000 -21.7  -7.1  240  22 11   8.2   4.5 | -20.7  -5.3  260  22 11   7.3   4.0
 19500 -20.4  -4.7  240  22 11   8.2   4.5 | -19.6  -3.3  260  21 11   7.3   4.0
 19000 -19.2  -2.6  240  21 11   8.2   4.5 | -18.5  -1.3  255  20 10   7.3   4.0
 18500 -18.0  -0.4  240  20 10   8.0   4.4 | -17.4   0.7  255  19 10   7.5   4.1
 18000 -16.8   1.8  240  19 10   8.0   4.4 | -16.3   2.7  255  19 10   7.5   4.1
 17500 -15.6   3.9  240  18  9   8.0   4.4 | -15.2   4.6  255  18  9   7.4   4.1
 17000 -14.4   6.1  240  17  9   8.1   4.4 | -14.1   6.6  250  17  9   7.1   3.9
 16500 -13.2   8.2  245  16  8   8.2   4.5 | -13.0   8.6  250  16  8   7.1   3.9
 16000 -12.1  10.2  245  15  8   7.0   3.8 | -12.0  10.4  250  15  8   7.2   3.9
 15500 -11.1  12.0  240  14  7   7.1   3.9 | -10.9  12.4  250  14  7   7.2   4.0
 15000 -10.1  13.8  240  13  7   6.8   3.7 |  -9.9  14.2  250  13  7   7.4   4.0
 14500  -9.1  15.6  240  12  6   6.7   3.7 |  -8.8  16.2  250  12  6   7.4   4.1
 14000  -7.6  18.3  235  11  6   7.6   4.2 |  -7.1  19.2  245  12  6   8.3   4.5
 13500  -6.5  20.3  230  10  5   7.6   4.2 |  -6.0  21.2  245  11  6   8.3   4.5
 13000  -5.4  22.3  230   9  5   7.5   4.1 |  -4.8  23.4  245  11  5   8.2   4.5
 12500  -4.3  24.3  225   8  4   7.5   4.1 |  -3.6  25.5  245   9  5   8.3   4.6
 12000  -3.2  26.2  220   7  4   7.7   4.2 |  -2.5  27.5  250   7  4   8.5   4.6
 11500  -2.1  28.2  220   6  3   7.8   4.3 |  -1.2  29.8  260   6  3   8.6   4.7
 11000  -1.0  30.2  220   4  2   6.5   3.6 |  -0.0  32.0  275   5  3   7.5   4.1
 10500  -0.0  32.0  225   3  2   5.6   3.1 |   1.1  34.0  290   5  3   7.9   4.3
 10250   0.4  32.7  230   3  2   9.2   5.0 |   1.7  35.1  300   5  3   5.7   3.1
 10000   1.3  34.3  235   3  1   9.9   5.4 |   2.1  35.8  305   5  3   6.8   3.7
  9750   1.8  35.2  255   2  1   6.7   3.7 |   2.8  37.0  310   5  3   9.5   5.2
  9500   2.4  36.3  270   2  1   8.0   4.4 |   3.4  38.1  310   5  3   9.1   5.0
  9250   2.9  37.2  290   2  1   6.1   3.3 |   4.1  39.4  315   6  3   8.1   4.5
  9000   3.3  37.9  295   3  1   6.2   3.4 |   4.7  40.5  315   6  3   7.0   3.8
  8750   3.9  39.0  300   3  2   7.9   4.3 |   5.2  41.4  315   6  3   7.4   4.1
  8500   4.4  39.9  305   3  2   7.4   4.1 |   5.8  42.4  315   6  3   7.3   4.0
  8250   5.0  41.0  305   4  2   8.9   4.9 |   6.4  43.5  315   6  3   7.8   4.3
  8000   5.7  42.3  305   4  2   9.8   5.4 |   7.0  44.6  310   6  3   7.5   4.1
  7750   6.4  43.5  305   4  2   9.3   5.1 |   7.5  45.5  310   6  3   6.5   3.6
  7500   7.1  44.8  305   4  2   9.8   5.4 |   8.0  46.4  305   6  3   7.2   4.0
  7250   7.8  46.0  305   4  2  10.8   5.9 |   8.5  47.3  305   7  3   8.4   4.6
  7000   8.6  47.5  300   4  2  10.4   5.7 |   9.1  48.4  300   7  3   8.8   4.8
  6750   9.4  48.9  300   4  2   8.8   4.8 |   9.8  49.6  300   6  3   9.3   5.1
  6500  10.0  50.0  300   4  2  10.3   5.6 |  10.5  50.9  300   6  3  10.3   5.7
  6250  10.9  51.6  300   4  2  12.5   6.8 |  11.3  52.3  295   6  3  11.0   6.1
  6000  11.8  53.2  295   4  2  10.5   5.8 |  12.1  53.8  295   6  3  10.5   5.8
  5750  12.5  54.5  295   4  2  11.1   6.1 |  12.9  55.2  295   6  3   8.9   4.9
  5500  13.5  56.3  295   4  2  14.7   8.1 |  13.5  56.3  295   6  3   7.8   4.3
  5250  14.7  58.5  300   4  2  15.1   8.3 |  14.1  57.4  295   6  3   8.5   4.7
  5000     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 at Walker Field in Grand
Junction, Colorado at

                   North Latitude:  39 deg 07 min 00.001 sec
                   West Longitude: 108 deg 31 min 59.998 sec
                   Elevation: 4839 feet (1475 meters)

and may not be representative of other areas along the Western Slope of
Colorado.  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.