Soaring Guidance
Issued by NWS Denver/Boulder, CO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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

000
UXUS97 KBOU 120040
SRGBOU

Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1840 MDT Saturday, April 11, 2015

This forecast is for Sunday, April 12, 2015:

If the trigger temperature of 62.9 F/17.2 C is reached...then
   Thermal Soaring Index....................... Excellent
   Maximum rate of lift........................ 1375 ft/min (7.0 m/s)
   Maximum height of thermals.................. 19537 ft MSL (14230 ft AGL)

Forecast maximum temperature................... 71.0 F/22.1 C
Time of trigger temperature.................... 1100 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................. 12751 ft MSL (7444 ft AGL)
Thermal soaring outlook for Monday 04/13....... Excellent

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....................... 14402 ft MSL (9095 ft AGL)
Wave soaring outlook for Monday 04/13.......... Poor

Remarks...

Sunrise/Sunset.................... 06:26:47 / 19:33:29 MDT
Total possible sunshine........... 13 hr 6 min 43 sec (786 min 43 sec)
Altitude of sun at 13:00:17 MDT... 59.01 degrees

Upper air data from numerical model forecast valid on 04/12/2015 at 0600 MDT

Freezing level.................. 11237 ft MSL (5930 ft AGL)
Convective condensation level... 17368 ft MSL (12061 ft AGL)
Lifted condensation level....... 18090 ft MSL (12783 ft AGL)
Lifted index.................... +0.5
K index......................... +6.1

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  -58.7 -73.7   265   23   12   0.4   0.2      M     M       M      M    M
 45000  -58.0 -72.4   270   27   14  -0.1  -0.0      M     M       M      M    M
 40000  -58.7 -73.7   275   20   10  -0.4  -0.2      M     M       M      M    M
 38000  -57.6 -71.7   270   20   10   4.2   2.3      M     M       M      M    M
 36000  -55.1 -67.2   265   23   12   4.2   2.3      M     M       M      M    M
 34000  -52.3 -62.1   255   26   14   7.6   4.2      M     M       M      M    M
 32000  -48.0 -54.4   250   25   13   7.2   4.0      M     M       M      M    M
 30000  -43.0 -45.4   250   25   13   7.5   4.1   32.5  90.6     8.2      M    M
 29000  -40.8 -41.4   255   26   14   7.5   4.1   31.6  88.8     7.5      M    M
 28000  -38.5 -37.3   260   28   14   7.5   4.1   30.7  87.3     7.0      M    M
 27000  -36.3 -33.3   260   29   15   7.2   3.9   30.0  86.1     6.5      M    M
 26000  -34.2 -29.6   265   29   15   6.9   3.8   28.8  83.8     5.6      M    M
 25000  -32.2 -26.0   270   29   15   6.9   3.8   27.7  81.9     4.8      M    M
 24000  -30.1 -22.2   270   29   15   6.9   3.8   26.8  80.2     4.1      M    M
 23000  -28.1 -18.6   270   27   14   6.8   3.7   25.6  78.0     3.2      M    M
 22000  -26.1 -15.0   265   25   13   6.8   3.7   24.5  76.1     2.3      M    M
 21000  -24.0 -11.2   265   23   12   6.7   3.6   23.5  74.4     1.5      M    M
 20000  -22.1  -7.8   255   21   11   6.6   3.6   22.3  72.2     0.5      M    M
 19500  -21.1  -6.0   255   20   10   6.6   3.6   21.8  71.2     0.0      M    M
 19000  -20.1  -4.2   250   19   10   6.7   3.7   21.2  70.2    -0.4   1333  6.8
 18500  -19.1  -2.4   245   18    9   7.4   4.1   20.8  69.4    -0.9   1289  6.5
 18000  -17.9  -0.2   245   18    9   8.5   4.7   20.5  68.9    -1.1   1237  6.3
 17500  -16.6   2.1   245   17    9   8.5   4.7   20.3  68.5    -1.3   1184  6.0
 17000  -15.3   4.5   245   16    8   9.1   5.0   20.1  68.2    -1.5   1130  5.7
 16500  -14.0   6.8   250   16    8   9.0   5.0   20.0  68.0    -1.6   1075  5.5
 16000  -12.0  10.4   255   15    8   8.8   4.8   19.8  67.7    -1.8    993  5.0
 15500  -10.7  12.7   260   16    8   8.8   4.8   19.7  67.4    -2.0    939  4.8
 15000   -9.4  15.1   265   16    8   9.0   4.9   19.5  67.1    -2.1    885  4.5
 14500   -8.0  17.6   270   18    9   9.0   5.0   19.4  66.9    -2.3    830  4.2
 14000   -6.7  19.9   275   20   10   8.5   4.7   19.3  66.7    -2.4    776  3.9
 13500   -5.5  22.1   280   21   11   8.4   4.6   19.0  66.2    -2.7    724  3.7
 13000   -4.2  24.4   280   23   12   8.2   4.5   18.8  65.8    -2.9    672  3.4
 12500   -3.1  26.4   280   24   12   8.0   4.4   18.5  65.3    -3.2    622  3.2
 12000   -1.9  28.6   285   25   13   8.4   4.6   18.2  64.8    -3.5    572  2.9
 11500   -0.6  30.9   285   24   13   8.7   4.8   18.1  64.5    -3.7    518  2.6
 11000    0.7  33.3   285   24   12   8.3   4.5   17.9  64.3    -3.8    464  2.4
 10500    1.9  35.4   290   24   12   6.9   3.8   17.6  63.7    -4.2    415  2.1
 10250    2.5  36.5   290   24   13  10.9   6.0   17.5  63.4    -4.3    390  2.0
 10000    3.4  38.1   295   24   12  11.6   6.4   17.7  63.9    -4.1    354  1.8
  9750    4.1  39.4   295   24   12   8.1   4.4   17.6  63.7    -4.2    326  1.7
  9500    4.8  40.6   295   24   12   9.1   5.0   17.5  63.6    -4.3    299  1.5
  9250    5.4  41.7   295   24   12   8.4   4.6   17.5  63.5    -4.3    272  1.4
  9000    6.0  42.8   295   23   12   8.2   4.5   17.4  63.2    -4.5    246  1.3
  8750    6.7  44.1   295   22   12   8.7   4.8   17.3  63.1    -4.6    220  1.1
  8500    7.3  45.1   295   22   11   8.7   4.7   17.2  62.9    -4.7    193  1.0
  8250    8.0  46.4   295   22   11   8.9   4.9   17.1  62.8    -4.7    166  0.8
  8000    8.7  47.7   295   21   11   8.8   4.8   17.1  62.7    -4.8    138  0.7
  7750    9.3  48.7   295   20   10   7.5   4.1   16.9  62.5    -4.9    113  0.6
  7500    9.8  49.6   295   19   10   7.0   3.8   16.7  62.1    -5.2     90  0.5
  7250   10.3  50.5   290   18    9   7.1   3.9   16.5  61.7    -5.4     67  0.3
  7000   10.8  51.4   290   17    9   6.9   3.8   16.3  61.4    -5.6     44  0.2
  6750   11.3  52.3   290   15    8   6.7   3.7   16.1  61.0    -5.9     22  0.1
  6500   11.8  53.2   290   14    7   4.9   2.7   15.8  60.4    -6.2      1  0.0
  6250   11.8  53.2   285   12    6  -4.7  -2.6   15.1  59.3    -6.9      M    M
  6000   11.1  52.0   275   11    5  -9.2  -5.0   13.7  56.7    -8.3      5  0.0
  5750   10.4  50.7   265    9    5 -13.8  -7.6   12.3  54.1    -9.8     21  0.1
  5500    8.3  46.9   245   10    5 -42.2 -23.2    9.6  49.3   -12.6     75  0.4

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

           04/12/2015 at 0900 MDT          |       04/12/2015 at 1200 MDT
                                           |
K index... +8.9  LI... +275.2              | K index... +15.0  LI... +275.2
CAPE... 0.0  CIN... -1.2                   | CAPE... 0.0  CIN... M
                                           |
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 -58.5 -73.3  265  23 12   0.8   0.4 | -58.4 -73.1  250  20 10   0.4   0.2
 45000 -57.2 -71.0  270  26 14  -0.4  -0.2 | -57.8 -72.0  255  24 13   0.1   0.1
 40000 -59.0 -74.2  245  27 14  -1.2  -0.6 | -57.9 -72.2  260  39 20  -0.0  -0.0
 38000 -58.0 -72.4  245  31 16   4.8   2.6 | -57.0 -70.6  260  45 23   2.9   1.6
 36000 -55.1 -67.2  250  37 19   4.8   2.7 | -55.3 -67.5  255  52 27   2.9   1.6
 34000 -52.0 -61.6  255  42 22   6.4   3.5 | -53.3 -63.9  250  58 30   7.3   4.0
 32000 -48.3 -54.9  255  43 22   6.3   3.4 | -48.7 -55.7  255  54 28   6.8   3.7
 30000 -43.9 -47.0  255  43 22   7.6   4.2 | -44.5 -48.1  255  51 26   7.6   4.2
 29000 -41.6 -42.9  260  43 22   7.6   4.2 | -42.2 -44.0  255  49 25   7.6   4.2
 28000 -39.3 -38.7  260  42 22   7.6   4.2 | -39.9 -39.8  255  46 24   7.6   4.2
 27000 -37.0 -34.6  260  42 21   7.7   4.2 | -37.6 -35.7  255  44 23   7.7   4.2
 26000 -34.7 -30.5  260  39 20   7.8   4.3 | -35.3 -31.5  260  42 22   7.8   4.3
 25000 -32.4 -26.3  260  36 18   7.8   4.3 | -32.9 -27.2  260  40 21   7.8   4.3
 24000 -30.0 -22.0  255  33 17   7.4   4.1 | -30.6 -23.1  260  38 20   7.8   4.3
 23000 -28.1 -18.6  255  29 15   6.1   3.4 | -28.3 -18.9  260  34 18   7.8   4.3
 22000 -26.3 -15.3  250  26 14   6.1   3.4 | -25.9 -14.6  265  31 16   7.8   4.3
 21000 -24.4 -11.9  245  23 12   7.1   3.9 | -23.6 -10.5  270  28 14   7.3   4.0
 20000 -22.2  -8.0  245  21 11   7.6   4.2 | -21.5  -6.7  275  26 14   7.1   3.9
 19500 -21.1  -6.0  245  19 10   7.6   4.2 | -20.5  -4.9  275  26 13   7.1   3.9
 19000 -19.9  -3.8  245  18  9   7.6   4.2 | -19.4  -2.9  280  25 13   7.1   3.9
 18500 -18.8  -1.8  245  17  9   8.2   4.5 | -18.3  -0.9  280  24 13   7.2   4.0
 18000 -17.5   0.5  250  16  8   8.8   4.8 | -17.3   0.9  285  26 14   7.3   4.0
 17500 -16.2   2.8  255  16  8   8.9   4.9 | -16.2   2.8  285  28 15   7.3   4.0
 17000 -14.9   5.2  265  17  9   7.9   4.3 | -15.2   4.6  285  30 15   6.3   3.4
 16500 -13.8   7.2  270  18  9   8.0   4.4 | -13.8   7.2  285  31 16   6.5   3.6
 16000 -12.1  10.2  275  21 11   7.3   4.0 | -12.8   9.0  285  31 16   7.0   3.8
 15500 -11.0  12.2  280  23 12   7.4   4.1 | -11.8  10.8  285  31 16   6.9   3.8
 15000  -9.9  14.2  280  24 12   7.1   3.9 | -10.7  12.7  285  31 16   8.4   4.6
 14500  -8.9  16.0  280  24 12   7.1   3.9 |  -9.5  14.9  285  31 16   8.3   4.5
 14000  -7.8  18.0  280  24 12   7.4   4.0 |  -8.2  17.2  285  31 16   8.3   4.6
 13500  -6.7  19.9  280  22 11   7.5   4.1 |  -7.0  19.4  285  30 16   8.3   4.6
 13000  -5.6  21.9  280  19 10   7.8   4.3 |  -5.8  21.6  285  29 15   8.4   4.6
 12500  -4.4  24.1  280  18  9   8.0   4.4 |  -4.5  23.9  280  28 14   8.4   4.6
 12000  -3.2  26.2  285  17  9   8.4   4.6 |  -3.3  26.1  280  27 14   8.3   4.6
 11500  -1.9  28.6  290  16  8   8.6   4.7 |  -2.0  28.4  280  25 13   8.3   4.5
 11000  -0.7  30.7  295  16  8   7.3   4.0 |  -0.8  30.6  280  23 12   8.1   4.5
 10500   0.3  32.5  300  15  8   5.7   3.1 |   0.4  32.7  280  22 11   8.6   4.7
 10250   0.7  33.3  300  15  8   8.5   4.7 |   1.0  33.8  275  21 11   5.8   3.2
 10000   1.5  34.7  305  14  7   9.8   5.4 |   1.3  34.3  275  20 10   6.4   3.5
  9750   2.1  35.8  305  14  7   7.8   4.3 |   2.0  35.6  275  19 10   9.6   5.3
  9500   2.7  36.9  305  14  7   8.4   4.6 |   2.6  36.7  275  19 10   8.9   4.9
  9250   3.3  37.9  310  14  7   7.9   4.4 |   3.3  37.9  275  18  9   8.7   4.8
  9000   3.9  39.0  310  15  8   7.6   4.2 |   3.9  39.0  275  17  9   8.0   4.4
  8750   4.5  40.1  310  15  8   7.9   4.4 |   4.5  40.1  275  16  8   7.9   4.3
  8500   5.1  41.2  310  16  8   7.9   4.3 |   5.1  41.2  275  14  7   7.9   4.4
  8250   5.7  42.3  310  16  8   8.3   4.6 |   5.7  42.3  280  13  6   7.8   4.3
  8000   6.3  43.3  310  17  9   8.9   4.9 |   6.2  43.2  280  11  5   7.9   4.3
  7750   7.0  44.6  310  17  9   8.5   4.7 |   6.8  44.2  285   9  5   8.1   4.5
  7500   7.6  45.7  310  17  9   8.3   4.6 |   7.4  45.3  290   8  4   8.5   4.7
  7250   8.3  46.9  310  17  9   8.8   4.8 |   8.1  46.6  290   7  4   9.9   5.4
  7000   8.9  48.0  310  16  8   9.1   5.0 |   8.9  48.0  295   7  4  10.8   5.9
  6750   9.6  49.3  305  16  8   8.1   4.4 |   9.7  49.5  295   7  4   9.7   5.3
  6500  10.1  50.2  305  15  8   5.9   3.2 |  10.4  50.7  295   7  4   9.8   5.4
  6250  10.4  50.7  305  14  7   3.4   1.9 |  11.2  52.2  295   7  4  10.7   5.9
  6000  10.6  51.1  300  11  6   3.5   1.9 |  11.9  53.4  295   7  4  10.1   5.6
  5750  10.8  51.4  295   9  5  -0.0  -0.0 |  12.7  54.9  295   7  3  11.8   6.5
  5500  10.5  50.9  280   6  3  -3.1  -1.7 |  13.8  56.8  295   7  3  19.3  10.6

           04/12/2015 at 1500 MDT          |       04/12/2015 at 1800 MDT
                                           |
K index... +10.4  LI... +274.1             | K index... +15.0  LI... +273.3
CAPE... 0.0  CIN... -2.3                   | CAPE... +0.9  CIN... -32.0
                                           |
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 -58.4 -73.1  250  23 12   0.7   0.4 | -58.5 -73.3  255  24 12   0.6   0.3
 45000 -57.2 -71.0  255  24 12   0.1   0.1 | -57.6 -71.7  260  28 14   0.4   0.2
 40000 -57.7 -71.9  270  47 24  -0.3  -0.2 | -57.1 -70.8  270  46 24   0.3   0.2
 38000 -57.2 -71.0  265  54 28   2.0   1.1 | -56.6 -69.9  270  51 26   1.2   0.7
 36000 -56.0 -68.8  265  58 30   2.0   1.1 | -55.9 -68.6  270  53 27   1.2   0.7
 34000 -54.3 -65.7  260  60 31   8.0   4.4 | -54.6 -66.3  270  54 28   8.3   4.5
 32000 -49.4 -56.9  260  55 28   7.3   4.0 | -49.4 -56.9  275  50 26   7.6   4.2
 30000 -44.9 -48.8  260  50 26   8.0   4.4 | -44.8 -48.6  275  47 24   7.8   4.3
 29000 -42.4 -44.3  265  47 24   8.0   4.4 | -42.5 -44.5  280  46 24   7.8   4.3
 28000 -40.0 -40.0  265  44 23   8.0   4.4 | -40.2 -40.4  280  45 23   7.8   4.3
 27000 -37.6 -35.7  270  42 22   7.7   4.2 | -37.8 -36.0  280  43 22   8.2   4.5
 26000 -35.4 -31.7  270  40 21   7.6   4.1 | -35.4 -31.7  275  40 21   8.3   4.5
 25000 -33.1 -27.6  275  38 20   7.6   4.1 | -32.9 -27.2  270  37 19   8.3   4.5
 24000 -30.8 -23.4  275  37 19   7.9   4.3 | -30.4 -22.7  270  35 18   7.9   4.4
 23000 -28.4 -19.1  275  34 18   8.3   4.6 | -28.1 -18.6  270  34 18   7.6   4.2
 22000 -25.9 -14.6  270  32 17   8.3   4.6 | -25.8 -14.4  275  34 18   7.6   4.2
 21000 -23.4 -10.1  270  30 16   7.8   4.3 | -23.5 -10.3  275  34 18   7.6   4.1
 20000 -21.1  -6.0  275  32 16   7.8   4.3 | -21.3  -6.3  280  33 17   7.6   4.2
 19500 -19.9  -3.8  280  32 17   7.8   4.3 | -20.2  -4.4  285  33 17   7.6   4.2
 19000 -18.8  -1.8  285  33 17   7.8   4.3 | -19.0  -2.2  285  33 17   7.5   4.1
 18500 -17.6   0.3  285  34 17   7.2   4.0 | -17.9  -0.2  285  32 17   8.5   4.7
 18000 -16.6   2.1  285  33 17   6.9   3.8 | -16.6   2.1  285  31 16   8.8   4.8
 17500 -15.6   3.9  285  32 17   6.9   3.8 | -15.2   4.6  280  30 16   8.8   4.8
 17000 -14.6   5.7  285  32 16   6.4   3.5 | -13.4   7.9  275  28 14   8.3   4.5
 16500 -13.2   8.2  290  31 16   6.9   3.8 | -12.2  10.0  275  26 14   8.4   4.6
 16000 -12.0  10.4  290  31 16   8.2   4.5 | -10.9  12.4  270  25 13   8.7   4.8
 15500 -10.8  12.6  285  31 16   8.2   4.5 |  -9.7  14.5  270  24 12   8.7   4.8
 15000  -9.6  14.7  285  31 16   8.4   4.6 |  -8.4  16.9  265  22 12   9.0   4.9
 14500  -8.3  17.1  285  30 16   8.4   4.6 |  -7.0  19.4  265  21 11   9.0   5.0
 14000  -7.1  19.2  280  29 15   8.6   4.7 |  -5.7  21.7  260  20 10   8.5   4.7
 13500  -5.8  21.6  280  27 14   8.7   4.8 |  -4.5  23.9  260  18 10   8.5   4.7
 13000  -4.6  23.7  275  25 13   8.0   4.4 |  -3.2  26.2  260  17  9   9.0   4.9
 12500  -3.5  25.7  275  23 12   7.8   4.3 |  -1.9  28.6  260  16  8   9.1   5.0
 12000  -2.3  27.9  270  20 10   8.4   4.6 |  -0.5  31.1  260  15  8   8.8   4.9
 11500  -1.1  30.0  270  18  9   8.6   4.7 |   0.8  33.4  260  14  7   8.8   4.8
 11000   0.1  32.2  270  16  8   7.5   4.1 |   2.1  35.8  260  13  7   7.7   4.2
 10500   1.2  34.2  270  13  7   6.3   3.5 |   3.2  37.8  260  11  6   6.7   3.7
 10250   1.7  35.1  270  12  6  10.5   5.8 |   3.7  38.7  260  11  5  10.0   5.5
 10000   2.7  36.9  270  10  5  11.6   6.4 |   4.6  40.3  260  10  5  10.3   5.7
  9750   3.3  37.9  270   9  5   8.1   4.5 |   5.2  41.4  260   9  4   7.1   3.9
  9500   4.0  39.2  270   8  4   9.2   5.0 |   5.7  42.3  260   8  4   8.4   4.6
  9250   4.7  40.5  270   7  4   8.5   4.7 |   6.3  43.3  260   7  3   6.6   3.6
  9000   5.3  41.5  270   7  4   9.4   5.2 |   6.8  44.2  265   5  3   6.5   3.6
  8750   6.1  43.0  270   7  4  10.5   5.8 |   7.3  45.1  275   4  2   8.2   4.5
  8500   6.8  44.2  275   7  3  10.2   5.6 |   7.9  46.2  290   3  2   7.3   4.0
  8250   7.6  45.7  275   7  3  10.5   5.8 |   8.5  47.3  305   3  2   9.5   5.2
  8000   8.4  47.1  275   7  3  10.3   5.7 |   9.3  48.7  315   3  2  11.0   6.1
  7750   9.1  48.4  275   6  3   9.5   5.2 |  10.0  50.0  315   3  2   9.1   5.0
  7500   9.8  49.6  275   6  3   9.3   5.1 |  10.7  51.3  320   3  2   8.9   4.9
  7250  10.5  50.9  275   6  3  10.2   5.6 |  11.4  52.5  320   3  2  10.1   5.5
  7000  11.3  52.3  275   6  3  10.6   5.8 |  12.2  54.0  320   3  2  10.7   5.9
  6750  12.1  53.8  275   6  3   9.4   5.2 |  12.9  55.2  320   3  2   9.3   5.1
  6500  12.8  55.0  275   6  3  10.0   5.5 |  13.6  56.5  320   3  2   9.4   5.2
  6250  13.6  56.5  275   6  3  11.7   6.4 |  14.4  57.9  320   3  2  10.8   5.9
  6000  14.5  58.1  280   6  3  11.3   6.2 |  15.2  59.4  325   3  2  10.7   5.9
  5750  15.3  59.5  280   6  3  12.0   6.6 |  16.0  60.8  325   3  2  10.1   5.5
  5500  16.4  61.5  280   6  3  18.7  10.2 |  16.7  62.1  325   4  2  11.3   6.2
________________________________________________________________________________

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.

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.