Soaring Guidance
Issued by NWS Denver/Boulder, 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 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
921
UXUS97 KBOU 171312
SRGBOU

Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0711 MDT Tuesday, September 17, 2019

This forecast is for Tuesday, September 17, 2019:

If the trigger temperature of 80.0 F/26.7 C is reached...then
   Thermal Soaring Index....................... Excellent
   Maximum rate of lift........................ 933 ft/min (4.7 m/s)
   Maximum height of thermals.................. 17380 ft MSL (12095 ft AGL)

Forecast maximum temperature................... 87.0 F/31.0 C
Time of trigger temperature.................... 1130 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 10308 ft MSL (5023 ft AGL)
Thermal soaring outlook for Wednesday 09/18.... Good

Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change.
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 39319 ft MSL (34034 ft AGL)
Wave soaring outlook for Wednesday 09/18....... Fair

Remarks... Windy conditions with isolated storms possible this afternoon.

Sunrise/Sunset.................... 06:42:30 / 19:05:29 MDT
Total possible sunshine........... 12 hr 22 min 59 sec (742 min 59 sec)
Altitude of sun at 12:54:00 MDT... 52.35 degrees

Upper air data from rawinsonde observation taken on 09/17/2019 at 0600 MDT

Freezing level.................. 14923 ft MSL (9638 ft AGL)
Convective condensation level... 17370 ft MSL (12085 ft AGL)
Lifted condensation level....... 17482 ft MSL (12197 ft AGL)
Lifted index.................... +0.2
K index......................... +20.7

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  -64.5 -84.1   220   46   24   1.8   1.0   85.8 186.5    32.1      M    M
 45000  -59.4 -74.9   225   48   25   4.6   2.5   69.7 157.5    24.4      M    M
 40000  -57.5 -71.5   230   61   31   1.6   0.9   50.2 122.4    13.1      M    M
 38000  -53.4 -64.1   225   61   32   6.8   3.7   47.5 117.5    11.6      M    M
 36000  -48.6 -55.5   215   54   28   9.5   5.2   46.1 115.0    10.9      M    M
 34000  -42.2 -44.0   215   50   26   9.4   5.1   45.7 114.3    11.0      M    M
 32000  -36.6 -33.9   210   46   24   9.4   5.2   45.6 114.0    11.1      M    M
 30000  -31.6 -24.9   195   38   20   8.1   4.4   44.5 112.1    10.5      M    M
 29000  -29.2 -20.6   190   36   19   8.1   4.4   43.8 110.9    10.1      M    M
 28000  -26.8 -16.2   195   35   18   8.4   4.6   43.1 109.6     9.7      M    M
 27000  -25.7 -14.3   195   34   18   4.7   2.6   40.9 105.6     8.0      M    M
 26000  -23.5 -10.3   200   34   17   7.3   4.0   40.0 103.9     7.3      M    M
 25000  -21.0  -5.8   205   33   17   8.8   4.8   39.4 102.9     7.0      M    M
 24000  -18.9  -2.0   210   33   17   8.3   4.5   38.3 101.0     6.2      M    M
 23000  -16.3   2.7   215   32   17   8.6   4.7   37.9 100.2     5.9      M    M
 22000  -13.8   7.2   220   31   16   8.8   4.8   37.5  99.5     5.6      M    M
 21000  -11.1  12.0   220   31   16   8.2   4.5   37.1  98.9     5.5      M    M
 20000   -8.7  16.3   225   30   15   6.1   3.3   36.5  97.7     5.0      M    M
 19500   -8.1  17.4   220   29   15   4.3   2.4   35.5  96.0     4.1      M    M
 19000   -7.5  18.5   215   28   14   1.5   0.8   34.6  94.3     3.3      M    M
 18500   -7.8  18.0   210   26   13   3.3   1.8   32.7  90.9     1.5      M    M
 18000   -7.0  19.4   200   24   13   5.9   3.2   32.1  89.8     0.9      M    M
 17500   -6.1  21.0   200   22   12   6.1   3.4   31.5  88.7     0.3      M    M
 17000   -4.8  23.4   205   20   10   6.3   3.5   30.6  87.0    -0.6   1092  5.5
 16500   -3.7  25.3   200   18    9   8.5   4.6   30.2  86.3    -1.0   1044  5.3
 16000   -2.5  27.5   195   17    9   8.3   4.6   29.9  85.9    -1.2    992  5.0
 15500   -1.2  29.8   190   15    8   8.6   4.7   29.7  85.4    -1.4    940  4.8
 15000    0.0  32.0   185   14    7   9.6   5.3   29.6  85.4    -1.6    887  4.5
 14500    1.4  34.5   190   13    7   9.2   5.0   29.6  85.2    -1.7    830  4.2
 14000    2.8  37.0   195   12    6   9.1   5.0   29.5  85.1    -1.8    773  3.9
 13500    4.2  39.6   200   10    5   9.2   5.0   29.4  84.9    -1.8    717  3.6
 13000    5.6  42.1   200    9    5   9.2   5.0   29.3  84.7    -1.9    660  3.4
 12500    7.0  44.6   210    9    5   9.2   5.0   29.2  84.5    -2.0    603  3.1
 12000    8.4  47.1   220    9    5   9.1   5.0   29.1  84.3    -2.1    547  2.8
 11500    9.8  49.6   235    9    5   8.2   4.5   29.0  84.1    -2.2    490  2.5
 11000   10.9  51.6   245   10    5   7.4   4.1   28.6  83.4    -2.5    442  2.2
 10500   12.1  53.8   250   11    6   7.3   4.0   28.2  82.7    -2.9    394  2.0
 10250   12.6  54.7   255   12    6   7.5   4.1   28.0  82.4    -3.1    369  1.9
 10000   13.2  55.8   255   12    6   7.6   4.2   27.8  82.1    -3.2    345  1.8
  9750   13.7  56.7   260   13    7   7.6   4.2   27.7  81.8    -3.4    321  1.6
  9500   14.3  57.7   265   14    7   7.6   4.2   27.5  81.5    -3.6    297  1.5
  9250   14.8  58.6   265   15    8   7.6   4.2   27.4  81.2    -3.8    273  1.4
  9000   15.4  59.7   270   16    8   7.6   4.2   27.2  81.0    -3.9    249  1.3
  8750   15.9  60.6   270   15    8   7.6   4.2   27.0  80.7    -4.1    225  1.1
  8500   16.5  61.7   270   14    7   7.6   4.2   26.9  80.4    -4.3    201  1.0
  8250   17.1  62.8   275   13    7   7.7   4.2   26.7  80.1    -4.5    177  0.9
  8000   17.6  63.7   275   12    6   7.7   4.2   26.6  79.8    -4.7    153  0.8
  7750   18.2  64.8   275   11    6   7.7   4.2   26.4  79.5    -4.9    129  0.7
  7500   18.7  65.7   280    9    5   7.7   4.2   26.2  79.2    -5.1    105  0.5
  7250   19.3  66.7   285    8    4   7.7   4.2   26.1  78.9    -5.3     81  0.4
  7000   19.8  67.6   290    7    4   7.7   4.2   25.9  78.6    -5.5     57  0.3
  6750   20.4  68.7   290    7    4   7.7   4.2   25.7  78.3    -5.7     33  0.2
  6500   20.9  69.6   285    7    4   7.7   4.2   25.6  78.0    -5.9      9  0.0
  6250   21.5  70.7   285    7    4   7.8   4.3   25.4  77.7    -6.1      M    M
  6000   22.0  71.6   280    7    4   7.2   3.9   25.2  77.4    -6.3      M    M
  5750   22.2  72.0   260    5    2  -5.0  -2.7   24.7  76.5    -6.9      M    M
  5500   20.8  69.4   210    4    2 -29.5 -16.2   22.7  72.9    -9.1      M    M

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

           09/17/2019 at 0900 MDT          |       09/17/2019 at 1200 MDT
                                           |
CAPE...    +1.4    LI...       +0.1        | CAPE...   +80.8    LI...       -0.6
CINH...   -33.0    K Index... +21.5        | CINH...   -45.1    K Index... +24.4
                                           |
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 -62.1 -79.8  215  23 12   2.0   1.1 | -61.5 -78.7  215  22 12   1.6   0.9
 45000 -58.9 -74.0  220  29 15   2.4   1.3 | -58.7 -73.7  220  28 14   3.0   1.6
 40000 -55.2 -67.4  220  31 16   5.5   3.0 | -54.1 -65.4  230  28 14   4.9   2.7
 38000 -51.6 -60.9  215  30 16   6.0   3.3 | -50.9 -59.6  225  28 14   5.3   2.9
 36000 -48.0 -54.4  210  29 15   6.0   3.3 | -47.7 -53.9  220  28 14   5.3   2.9
 34000 -42.7 -44.9  205  27 14   8.6   4.7 | -43.0 -45.4  220  27 14   7.7   4.2
 32000 -37.5 -35.5  205  25 13   8.6   4.7 | -38.4 -37.1  220  25 13   7.7   4.2
 30000 -32.7 -26.9  205  23 12   7.9   4.3 | -33.8 -28.8  220  24 12   7.7   4.2
 29000 -30.3 -22.5  205  22 12   7.9   4.4 | -31.5 -24.7  220  23 12   7.7   4.2
 28000 -28.0 -18.4  200  22 11   7.9   4.3 | -29.2 -20.6  220  23 12   7.7   4.2
 27000 -25.8 -14.4  205  21 11   7.1   3.9 | -27.0 -16.6  220  22 11   7.3   4.0
 26000 -23.7 -10.7  205  21 11   7.1   3.9 | -24.8 -12.6  225  22 11   7.3   4.0
 25000 -21.6  -6.9  210  21 11   7.1   3.9 | -22.6  -8.7  225  21 11   7.3   4.0
 24000 -19.7  -3.5  210  20 10   6.3   3.4 | -20.5  -4.9  225  20 10   7.1   3.9
 23000 -17.8  -0.0  210  19 10   6.3   3.4 | -18.4  -1.1  225  20 10   7.2   3.9
 22000 -16.0   3.2  210  17  9   6.2   3.4 | -16.3   2.7  225  19 10   7.2   3.9
 21000 -14.1   6.6  210  16  8   6.7   3.7 | -14.2   6.4  225  18  9   7.1   3.9
 20000 -12.1  10.2  210  15  8   6.7   3.7 | -12.1  10.2  220  17  9   7.1   3.9
 19500 -10.7  12.7  210  14  7   6.7   3.7 | -10.6  12.9  220  16  8   7.1   3.9
 19000  -9.6  14.7  210  13  7   7.5   4.1 |  -9.5  14.9  220  15  8   7.5   4.1
 18500  -8.5  16.7  205  13  6   7.4   4.1 |  -8.4  16.9  215  15  8   7.5   4.1
 18000  -7.4  18.7  205  12  6   7.6   4.2 |  -7.3  18.9  215  15  7   7.7   4.2
 17500  -6.3  20.7  205  11  6   7.9   4.4 |  -6.2  20.8  215  14  7   8.0   4.4
 17000  -5.1  22.8  205  11  6   7.9   4.3 |  -5.0  23.0  215  14  7   8.0   4.4
 16500  -3.9  25.0  210  10  5   8.4   4.6 |  -3.8  25.2  215  13  7   8.1   4.4
 16000  -2.7  27.1  210  10  5   8.3   4.6 |  -2.6  27.3  215  12  6   8.1   4.4
 15500  -1.4  29.5  210   9  5   8.3   4.6 |  -1.4  29.5  215  12  6   7.6   4.2
 15000  -0.2  31.6  210   9  4   8.3   4.6 |  -0.4  31.3  220  11  6   7.5   4.1
 14500   1.0  33.8  210   8  4   8.3   4.6 |   0.7  33.3  220  11  5   7.6   4.1
 14000   2.3  36.1  215   8  4   8.4   4.6 |   1.9  35.4  225  10  5   7.7   4.2
 13500   3.5  38.3  215   7  4   8.4   4.6 |   3.0  37.4  225   9  5   7.8   4.3
 13000   4.8  40.6  220   7  4   8.4   4.6 |   4.1  39.4  230   9  4   8.0   4.4
 12500   6.0  42.8  225   6  3   8.4   4.6 |   5.3  41.5  230   8  4   7.9   4.4
 12000   7.2  45.0  230   6  3   7.9   4.3 |   6.6  43.9  235   7  4   8.9   4.9
 11500   8.4  47.1  235   6  3   8.0   4.4 |   7.9  46.2  235   7  4   8.9   4.9
 11000   9.5  49.1  240   6  3   6.8   3.8 |   9.1  48.4  235   6  3   7.8   4.3
 10500  10.5  50.9  250   6  3   6.6   3.6 |  10.3  50.5  235   6  3   9.9   5.4
 10250  11.0  51.8  255   6  3  10.2   5.6 |  11.1  52.0  235   6  3  12.0   6.6
 10000  11.9  53.4  255   6  3  10.6   5.8 |  11.9  53.4  240   6  3   9.7   5.3
  9750  12.5  54.5  260   6  3   7.6   4.2 |  12.6  54.7  240   6  3   9.1   5.0
  9500  13.1  55.6  265   7  3   9.0   5.0 |  13.3  55.9  240   6  3   9.7   5.3
  9250  13.7  56.7  270   7  4   6.4   3.5 |  14.0  57.2  240   6  3   7.6   4.1
  9000  14.1  57.4  270   7  4   6.7   3.7 |  14.5  58.1  240   5  3   8.5   4.7
  8750  14.8  58.6  270   7  4   9.4   5.2 |  15.3  59.5  245   5  3  11.2   6.1
  8500  15.4  59.7  275   8  4   8.8   4.8 |  16.1  61.0  245   5  3  10.5   5.7
  8250  16.0  60.8  275   8  4   7.0   3.8 |  16.9  62.4  245   5  3  10.3   5.6
  8000  16.4  61.5  275   8  4   5.6   3.1 |  17.6  63.7  245   5  2   9.8   5.4
  7750  16.9  62.4  275   9  4   6.5   3.5 |  18.3  64.9  245   5  2   9.9   5.4
  7500  17.3  63.1  275   9  4   6.0   3.3 |  19.1  66.4  245   5  2   9.8   5.4
  7250  17.7  63.9  275   9  4   4.5   2.5 |  19.8  67.6  245   4  2   9.5   5.2
  7000  18.0  64.4  275   8  4   4.1   2.2 |  20.5  68.9  245   4  2   9.7   5.3
  6750  18.3  64.9  270   8  4   4.8   2.6 |  21.3  70.3  245   4  2  10.8   5.9
  6500  18.7  65.7  265   7  4   6.3   3.5 |  22.1  71.8  245   4  2  10.8   5.9
  6250  19.2  66.6  265   6  3   7.7   4.2 |  22.8  73.0  245   4  2  10.2   5.6
  6000  19.8  67.6  260   6  3   7.4   4.1 |  23.6  74.5  245   4  2   9.9   5.4
  5750  20.3  68.5  255   5  2   8.6   4.7 |  24.4  75.9  245   3  2  11.5   6.3
  5500  21.1  70.0  250   4  2  13.0   7.1 |  25.5  77.9  245   3  2  20.7  11.3

           09/17/2019 at 1500 MDT          |       09/17/2019 at 1800 MDT
                                           |
CAPE...  +313.0    LI...       -1.6        | CAPE...   +63.0    LI...       +0.1
CINH...   -15.0    K Index... +28.5        | CINH...   -42.4    K Index... +25.9
                                           |
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 -62.0 -79.6  225  20 11   2.1   1.1 | -62.4 -80.3  235  18  9   1.6   0.9
 45000 -58.5 -73.3  225  25 13   3.2   1.7 | -59.4 -74.9  235  22 11   3.3   1.8
 40000 -53.6 -64.5  240  28 15   5.3   2.9 | -54.3 -65.7  245  26 14   5.3   2.9
 38000 -50.2 -58.4  245  27 14   5.7   3.1 | -51.0 -59.8  250  24 13   5.5   3.0
 36000 -46.8 -52.2  245  26 13   5.7   3.1 | -47.7 -53.9  255  23 12   5.5   3.0
 34000 -42.7 -44.9  255  23 12   6.3   3.4 | -43.1 -45.6  260  20 10   7.4   4.1
 32000 -39.0 -38.2  260  20 10   6.3   3.5 | -38.6 -37.5  265  17  9   7.5   4.1
 30000 -34.4 -29.9  260  19 10   8.1   4.5 | -33.8 -28.8  265  16  8   8.3   4.6
 29000 -32.0 -25.6  260  19 10   8.1   4.5 | -31.3 -24.3  265  16  8   8.3   4.6
 28000 -29.6 -21.3  255  19 10   8.1   4.5 | -28.8 -19.8  265  15  8   8.3   4.6
 27000 -27.1 -16.8  250  19 10   8.1   4.4 | -26.3 -15.3  265  15  8   8.5   4.6
 26000 -24.7 -12.5  250  19 10   8.1   4.4 | -23.7 -10.7  265  15  8   8.5   4.6
 25000 -22.3  -8.1  245  19 10   8.1   4.5 | -21.2  -6.2  260  15  8   8.5   4.7
 24000 -20.1  -4.2  240  19 10   7.1   3.9 | -18.7  -1.7  260  15  8   8.0   4.4
 23000 -18.0  -0.4  240  18  9   7.1   3.9 | -16.4   2.5  255  15  8   8.0   4.4
 22000 -15.9   3.4  235  18  9   7.2   4.0 | -14.0   6.8  255  14  7   8.2   4.5
 21000 -13.9   7.0  235  17  9   6.5   3.6 | -12.1  10.2  250  14  7   5.7   3.1
 20000 -12.0  10.4  235  16  8   6.6   3.6 | -10.4  13.3  245  14  7   5.7   3.1
 19500 -10.6  12.9  235  15  8   6.6   3.6 |  -9.2  15.4  245  14  7   5.8   3.2
 19000  -9.6  14.7  235  14  7   7.1   3.9 |  -8.4  16.9  245  14  7   5.1   2.8
 18500  -8.6  16.5  240  14  7   7.1   3.9 |  -7.7  18.1  245  13  7   5.3   2.9
 18000  -7.6  18.3  240  14  7   7.5   4.1 |  -7.0  19.4  245  13  7   5.9   3.2
 17500  -6.5  20.3  240  13  7   7.9   4.3 |  -6.0  21.2  245  12  6   6.7   3.7
 17000  -5.3  22.5  240  13  7   7.9   4.3 |  -5.1  22.8  245  12  6   6.6   3.6
 16500  -4.2  24.4  240  12  6   8.4   4.6 |  -4.1  24.6  245  11  6   7.7   4.2
 16000  -2.9  26.8  240  12  6   8.4   4.6 |  -3.0  26.6  245  11  5   7.6   4.2
 15500  -1.7  28.9  240  11  6   8.6   4.7 |  -1.9  28.6  240  10  5   8.3   4.5
 15000  -0.4  31.3  240  11  6   8.7   4.8 |  -0.7  30.7  240   9  5   8.6   4.7
 14500   0.8  33.4  240  10  5   8.8   4.8 |   0.6  33.1  240   9  5   8.7   4.8
 14000   2.1  35.8  240  10  5   8.9   4.9 |   1.9  35.4  235   9  5   9.0   4.9
 13500   3.5  38.3  240  10  5   8.9   4.9 |   3.2  37.8  235   9  4   9.0   5.0
 13000   4.8  40.6  240   9  5   9.3   5.1 |   4.6  40.3  235   8  4   9.3   5.1
 12500   6.2  43.2  240   9  5   9.3   5.1 |   6.0  42.8  235   8  4   9.3   5.1
 12000   7.6  45.7  240   8  4   9.3   5.1 |   7.3  45.1  235   8  4   9.3   5.1
 11500   9.0  48.2  245   8  4   9.4   5.2 |   8.7  47.7  240   7  4   9.5   5.2
 11000  10.3  50.5  245   8  4   8.6   4.7 |  10.0  50.0  240   7  3   7.8   4.3
 10500  11.6  52.9  245   7  4  10.5   5.8 |  11.2  52.2  245   6  3  10.2   5.6
 10250  12.5  54.5  245   8  4  12.4   6.8 |  12.1  53.8  250   6  3  12.4   6.8
 10000  13.3  55.9  245   8  4  10.2   5.6 |  12.9  55.2  250   6  3  10.0   5.5
  9750  14.0  57.2  245   8  4   9.7   5.3 |  13.6  56.5  250   6  3   9.4   5.2
  9500  14.8  58.6  245   8  4  10.1   5.6 |  14.3  57.7  255   6  3  10.1   5.5
  9250  15.5  59.9  245   7  4   8.9   4.9 |  15.0  59.0  255   6  3   8.2   4.5
  9000  16.1  61.0  250   7  4   9.1   5.0 |  15.6  60.1  255   6  3   8.7   4.8
  8750  16.9  62.4  250   7  4  10.6   5.8 |  16.4  61.5  260   6  3  10.9   6.0
  8500  17.7  63.9  250   7  4  10.0   5.5 |  17.2  63.0  260   6  3  10.4   5.7
  8250  18.4  65.1  250   7  4  11.3   6.2 |  17.9  64.2  260   6  3  10.0   5.5
  8000  19.3  66.7  250   7  4  10.6   5.8 |  18.7  65.7  260   6  3   9.6   5.3
  7750  20.0  68.0  250   7  4   8.8   4.8 |  19.4  66.9  265   6  3   9.9   5.4
  7500  20.7  69.3  250   7  4   9.3   5.1 |  20.1  68.2  265   6  3   9.8   5.4
  7250  21.4  70.5  250   7  4   9.9   5.5 |  20.8  69.4  265   6  3   9.6   5.3
  7000  22.2  72.0  250   7  3  10.3   5.7 |  21.6  70.9  265   6  3   9.6   5.3
  6750  22.9  73.2  250   7  3   9.6   5.3 |  22.3  72.1  265   6  3   9.9   5.4
  6500  23.6  74.5  250   6  3  10.1   5.5 |  23.0  73.4  270   6  3  10.2   5.6
  6250  24.4  75.9  250   6  3  11.0   6.0 |  23.8  74.8  270   6  3  10.3   5.6
  6000  25.2  77.4  255   6  3  11.3   6.2 |  24.6  76.3  270   6  3  10.3   5.7
  5750  26.1  79.0  255   6  3   9.6   5.2 |  25.3  77.5  270   5  3   9.3   5.1
  5500  26.8  80.2  255   5  3  13.2   7.3 |  26.0  78.8  275   5  2   9.8   5.4
________________________________________________________________________________

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

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

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

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

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

DEFINITIONS:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

042613



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