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

000
UXUS97 KBOU 220128
SRGBOU

Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1928 MDT Tuesday, April 21, 2015

This forecast is for Wednesday, April 22, 2015:

If the trigger temperature of 59.3 F/15.2 C is reached...then
   Thermal Soaring Index....................... Excellent
   Maximum rate of lift........................ 860 ft/min (4.4 m/s)
   Maximum height of thermals.................. 15324 ft MSL (10017 ft AGL)

Forecast maximum temperature................... 68.0 F/20.5 C
Time of trigger temperature.................... 1145 MDT
Time of overdevelopment........................ 1500 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 10795 ft MSL (5489 ft AGL)
Thermal soaring outlook for Thursday 04/23..... Excellent

Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Little change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak NVA
Potential height of wave....................... 27473 ft MSL (22166 ft AGL)
Wave soaring outlook for Thursday 04/23........ Poor

Remarks... Upper ridge will remain over colorado on Wednesday with weak westerly
           flow aloft. Airmass becoming unstable in the afternoon with scattered
           showers developing.

Sunrise/Sunset.................... 06:12:13 / 19:43:34 MDT
Total possible sunshine........... 13 hr 31 min 21 sec (811 min 21 sec)
Altitude of sun at 12:58:03 MDT... 62.51 degrees

Upper air data from numerical model forecast valid on 04/22/2015 at 0600 MDT

Freezing level.................. 11017 ft MSL (5710 ft AGL)
Convective condensation level... 13200 ft MSL (7893 ft AGL)
Lifted condensation level....... 13636 ft MSL (8329 ft AGL)
Lifted index.................... -3.1
K index......................... +21.6

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  -58.9 -74.0   275   36   18   0.5   0.3      M     M       M      M    M
 45000  -58.2 -72.8   270   39   20   1.0   0.5      M     M       M      M    M
 40000  -62.8 -81.0   280   18    9  -3.3  -1.8      M     M       M      M    M
 38000  -62.4 -80.3   290   13    6   6.5   3.6      M     M       M      M    M
 36000  -58.5 -73.3   300   13    7   6.5   3.6      M     M       M      M    M
 34000  -54.5 -66.1   310   15    8   7.3   4.0      M     M       M      M    M
 32000  -49.6 -57.3   300   18    9   7.3   4.0      M     M       M      M    M
 30000  -45.2 -49.4   290   21   11   7.6   4.2   30.1  86.2     7.6      M    M
 29000  -42.9 -45.2   290   22   11   7.6   4.2   29.2  84.5     7.0      M    M
 28000  -40.6 -41.1   290   23   12   7.6   4.2   28.4  83.1     6.5      M    M
 27000  -38.3 -36.9   290   24   13   8.0   4.4   27.7  81.9     6.0      M    M
 26000  -35.8 -32.4   290   24   13   8.4   4.6   27.1  80.8     5.6      M    M
 25000  -33.3 -27.9   290   24   12   8.4   4.6   26.6  79.9     5.2      M    M
 24000  -30.8 -23.4   295   24   13   8.4   4.6   26.2  79.2     5.0      M    M
 23000  -28.3 -18.9   290   23   12   8.4   4.6   25.6  78.1     4.5      M    M
 22000  -25.8 -14.4   285   21   11   8.4   4.6   25.1  77.2     4.1      M    M
 21000  -23.3  -9.9   280   19   10   7.6   4.2   24.7  76.4     3.8      M    M
 20000  -21.1  -6.0   280   17    9   7.3   4.0   23.7  74.7     3.0      M    M
 19500  -20.1  -4.2   280   17    9   7.3   4.0   23.3  73.9     2.6      M    M
 19000  -19.0  -2.2   275   16    8   7.3   4.0   22.9  73.1     2.3      M    M
 18500  -17.9  -0.2   275   15    8   7.4   4.0   22.5  72.5     2.0      M    M
 18000  -16.8   1.8   275   14    7   7.5   4.1   22.1  71.7     1.6      M    M
 17500  -15.7   3.7   275   14    7   7.4   4.1   21.7  71.0     1.3      M    M
 17000  -14.0   6.8   275   13    7   7.9   4.3   21.2  70.1     0.8      M    M
 16500  -12.8   9.0   275   13    6   8.0   4.4   20.9  69.6     0.5      M    M
 16000  -11.6  11.1   275   12    6   8.4   4.6   20.6  69.1     0.3      M    M
 15500  -10.3  13.5   275   12    6   8.4   4.6   20.4  68.7     0.0      M    M
 15000   -9.1  15.6   275   12    6   8.9   4.9   20.2  68.3    -0.2    815  4.1
 14500   -7.8  18.0   275   11    6   8.9   4.9   20.0  68.1    -0.3    761  3.9
 14000   -6.5  20.3   275   11    6   8.7   4.8   19.9  67.8    -0.5    707  3.6
 13500   -5.2  22.6   270   12    6   8.6   4.7   19.7  67.5    -0.7    654  3.3
 13000   -3.9  25.0   270   12    6   8.1   4.4   19.5  67.1    -0.9    602  3.1
 12500   -2.8  27.0   265   13    7   7.6   4.2   19.2  66.5    -1.2    553  2.8
 12000   -1.7  28.9   260   14    7   6.9   3.8   18.8  65.9    -1.5    504  2.6
 11500   -0.8  30.6   250   14    7   6.2   3.4   18.3  64.9    -2.1    463  2.4
 11000    0.1  32.2   240   15    8   5.8   3.2   17.7  63.8    -2.7    422  2.1
 10500    0.8  33.4   235   15    8   5.1   2.8   17.0  62.6    -3.5    385  2.0
 10250    1.2  34.2   230   15    8   6.9   3.8   16.7  62.0    -3.8    366  1.9
 10000    1.8  35.2   225   15    8   7.8   4.3   16.5  61.8    -4.0    341  1.7
  9750    2.3  36.1   220   15    8   6.7   3.7   16.3  61.3    -4.2    319  1.6
  9500    2.8  37.0   220   15    8   7.0   3.9   16.1  60.9    -4.5    296  1.5
  9250    3.3  37.9   215   15    8   6.7   3.7   15.9  60.5    -4.7    274  1.4
  9000    3.8  38.8   215   14    7   5.4   3.0   15.6  60.1    -5.0    253  1.3
  8750    4.1  39.4   220   13    7   4.7   2.6   15.2  59.4    -5.4    235  1.2
  8500    4.5  40.1   220   13    7   5.2   2.9   14.8  58.7    -5.7    216  1.1
  8250    4.9  40.8   225   12    6   4.7   2.6   14.5  58.0    -6.1    197  1.0
  8000    5.2  41.4   225   11    6   3.9   2.1   14.0  57.3    -6.5    180  0.9
  7750    5.5  41.9   230   10    5   3.9   2.1   13.6  56.5    -7.0    164  0.8
  7500    5.8  42.4   230    9    5   4.4   2.4   13.2  55.7    -7.4    147  0.7
  7250    6.1  43.0   235    8    4   3.2   1.8   12.7  54.9    -7.8    130  0.7
  7000    6.3  43.3   235    8    4   2.1   1.2   12.2  53.9    -8.4    118  0.6
  6750    6.4  43.5   235    7    4   1.9   1.0   11.6  52.9    -9.0    106  0.5
  6500    6.5  43.7   235    6    3   1.1   0.6   11.0  51.7    -9.7     97  0.5
  6250    6.5  43.7   240    5    3   0.8   0.5   10.3  50.5   -10.5     89  0.5
  6000    6.5  43.7   245    3    2   0.5   0.3    9.6  49.3   -11.2     81  0.4
  5750    6.5  43.7   280    1    1   1.4   0.8    8.9  48.1   -12.0     74  0.4
  5500    6.5  43.7   350    2    1  -4.6  -2.5    8.2  46.7   -12.8     69  0.3

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

           04/22/2015 at 0900 MDT          |       04/22/2015 at 1200 MDT
                                           |
K index... +18.4  LI... +273.6             | K index... +15.7  LI... +271.2
CAPE... 0.0  CIN... -0.1                   | CAPE... +282.3  CIN... -78.2
                                           |
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 -58.9 -74.0  275  34 18   0.8   0.5 | -58.6 -73.5  270  35 18   0.7   0.4
 45000 -57.7 -71.9  270  39 20   1.3   0.7 | -57.6 -71.7  270  39 20   1.1   0.6
 40000 -62.8 -81.0  250  16  8  -3.6  -2.0 | -62.1 -79.8  245  21 11  -3.2  -1.8
 38000 -62.6 -80.7  245  10  5   6.4   3.5 | -61.9 -79.4  235  16  8   5.7   3.1
 36000 -58.8 -73.8  260   8  4   6.3   3.5 | -58.1 -72.6  235  11  6   5.7   3.1
 34000 -54.4 -65.9  280   8  4   7.5   4.1 | -54.5 -66.1  235   8  4   7.4   4.1
 32000 -49.9 -57.8  270  11  6   7.5   4.1 | -50.0 -58.0  245  12  6   7.4   4.1
 30000 -45.4 -49.7  270  14  7   7.9   4.3 | -45.5 -49.9  255  15  8   7.8   4.3
 29000 -43.0 -45.4  270  16  8   8.0   4.4 | -43.2 -45.8  255  16  8   7.8   4.3
 28000 -40.6 -41.1  270  17  9   8.0   4.4 | -40.8 -41.4  255  18  9   7.8   4.3
 27000 -38.2 -36.8  270  18  9   8.2   4.5 | -38.5 -37.3  255  19 10   8.2   4.5
 26000 -35.7 -32.3  275  19 10   8.5   4.6 | -35.9 -32.6  260  19 10   8.6   4.7
 25000 -33.1 -27.6  275  20 10   8.5   4.6 | -33.4 -28.1  260  19 10   8.6   4.7
 24000 -30.6 -23.1  280  21 11   8.4   4.6 | -30.8 -23.4  265  19 10   8.5   4.6
 23000 -28.1 -18.6  285  21 11   8.3   4.5 | -28.3 -18.9  265  19 10   8.1   4.4
 22000 -25.7 -14.3  285  21 11   8.3   4.5 | -25.9 -14.6  270  18 10   8.1   4.4
 21000 -23.2  -9.8  290  20 10   7.7   4.2 | -23.5 -10.3  270  18  9   7.8   4.3
 20000 -21.0  -5.8  285  19 10   7.5   4.1 | -21.2  -6.2  275  19 10   7.7   4.2
 19500 -19.9  -3.8  285  19 10   7.5   4.1 | -20.1  -4.2  280  19 10   7.7   4.2
 19000 -18.8  -1.8  285  18  9   7.5   4.1 | -18.9  -2.0  280  19 10   7.7   4.2
 18500 -17.7   0.1  285  18  9   7.3   4.0 | -17.8  -0.0  285  19 10   7.7   4.2
 18000 -16.6   2.1  285  17  9   7.0   3.8 | -16.0   3.2  285  20 10   7.7   4.2
 17500 -15.0   5.0  290  16  8   7.2   4.0 | -14.9   5.2  290  20 10   8.3   4.5
 17000 -13.9   7.0  290  16  8   7.4   4.1 | -13.6   7.5  290  20 10   8.6   4.7
 16500 -12.9   8.8  290  15  8   7.5   4.1 | -12.3   9.9  290  20 10   8.6   4.7
 16000 -11.7  10.9  290  15  8   8.5   4.6 | -11.1  12.0  295  19 10   8.3   4.5
 15500 -10.4  13.3  295  15  7   8.4   4.6 |  -9.9  14.2  295  18  9   8.3   4.5
 15000  -9.1  15.6  295  14  7   8.8   4.9 |  -8.6  16.5  295  18  9   8.9   4.9
 14500  -7.8  18.0  295  14  7   8.8   4.8 |  -7.3  18.9  300  17  9   8.9   4.9
 14000  -6.5  20.3  295  14  7   9.0   4.9 |  -6.0  21.2  300  16  8   8.6   4.7
 13500  -5.2  22.6  295  14  7   9.1   5.0 |  -4.7  23.5  300  15  8   8.6   4.7
 13000  -3.8  25.2  295  14  7   8.9   4.9 |  -3.4  25.9  305  14  7   8.8   4.8
 12500  -2.5  27.5  295  14  7   8.8   4.8 |  -2.1  28.2  305  14  7   8.8   4.9
 12000  -1.2  29.8  290  13  7   8.2   4.5 |  -0.8  30.6  305  13  7   8.8   4.9
 11500  -0.1  31.8  285  13  7   7.7   4.2 |   0.5  32.9  305  12  6   8.8   4.8
 11000   1.0  33.8  275  13  7   6.7   3.7 |   1.8  35.2  305  12  6   7.8   4.3
 10500   1.8  35.2  265  12  6   5.5   3.0 |   2.8  37.0  305  11  5   6.6   3.6
 10250   2.2  36.0  260  12  6   7.1   3.9 |   3.4  38.1  305  10  5   8.5   4.6
 10000   2.8  37.0  250  12  6   6.8   3.8 |   4.0  39.2  305   9  5   8.3   4.6
  9750   3.2  37.8  245  12  6   5.0   2.8 |   4.5  40.1  300   8  4   6.1   3.4
  9500   3.5  38.3  240  12  6   5.6   3.1 |   5.0  41.0  295   7  3   7.0   3.9
  9250   3.9  39.0  230  11  6   5.3   2.9 |   5.5  41.9  290   6  3   5.7   3.1
  9000   4.3  39.7  225  11  6   5.6   3.1 |   5.8  42.4  280   4  2   4.6   2.5
  8750   4.7  40.5  220  11  6   6.1   3.3 |   6.1  43.0  260   3  1   5.4   3.0
  8500   5.2  41.4  210  12  6   6.2   3.4 |   6.5  43.7  225   2  1   5.5   3.0
  8250   5.6  42.1  205  12  6   6.0   3.3 |   6.9  44.4  185   2  1   5.6   3.1
  8000   6.0  42.8  200  12  6   5.5   3.0 |   7.3  45.1  165   3  1   6.2   3.4
  7750   6.4  43.5  195  12  6   5.1   2.8 |   7.7  45.9  155   3  1   7.0   3.8
  7500   6.8  44.2  195  12  6   5.4   3.0 |   8.2  46.8  145   2  1   6.8   3.7
  7250   7.2  45.0  190  12  6   3.8   2.1 |   8.7  47.7  135   2  1   8.9   4.9
  7000   7.4  45.3  190  11  6   2.5   1.4 |   9.5  49.1  130   2  1  10.9   6.0
  6750   7.5  45.5  190  10  5   1.7   1.0 |  10.2  50.4  125   2  1   9.6   5.3
  6500   7.6  45.7  190   9  4   0.2   0.1 |  10.9  51.6  120   2  1   9.7   5.3
  6250   7.5  45.5  190   7  4  -0.4  -0.2 |  11.7  53.1  115   2  1  10.9   6.0
  6000   7.4  45.3  190   5  2  -0.9  -0.5 |  12.5  54.5  115   1  1  11.4   6.3
  5750   7.3  45.1  190   2  1   0.0   0.0 |  13.4  56.1  110   1  1  10.6   5.8
  5500   7.5  45.5  000   0  0   8.2   4.5 |  14.3  57.7  105   1  1  16.0   8.8

           04/22/2015 at 1500 MDT          |       04/22/2015 at 1800 MDT
                                           |
K index... +18.7  LI... +269.5             | K index... +20.9  LI... +272.6
CAPE... +592.5  CIN... -9.8                | CAPE... +42.5  CIN... -58.5
                                           |
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 -58.6 -73.5  270  34 17   0.7   0.4 | -58.8 -73.8  265  35 18   0.7   0.4
 45000 -57.6 -71.7  265  37 19   1.0   0.6 | -57.8 -72.0  260  39 20   1.0   0.5
 40000 -60.4 -76.7  255  30 15  -1.9  -1.1 | -60.1 -76.2  265  38 19  -1.5  -0.8
 38000 -60.0 -76.0  255  26 14   3.7   2.0 | -59.6 -75.3  260  38 19   3.0   1.7
 36000 -57.8 -72.0  250  22 12   3.7   2.0 | -57.8 -72.0  255  39 20   3.0   1.7
 34000 -55.1 -67.2  245  20 10   8.2   4.5 | -55.5 -67.9  250  39 20   8.9   4.9
 32000 -50.4 -58.7  255  26 14   7.9   4.3 | -50.5 -58.9  250  33 17   8.4   4.6
 30000 -45.6 -50.1  260  31 16   9.0   4.9 | -45.3 -49.5  250  28 14   9.3   5.1
 29000 -42.3 -44.1  265  29 15   9.0   4.9 | -41.9 -43.4  255  25 13   9.3   5.1
 28000 -39.6 -39.3  265  28 14   9.0   4.9 | -39.1 -38.4  260  22 11   9.3   5.1
 27000 -36.9 -34.4  270  26 14   8.1   4.5 | -36.4 -33.5  265  20 11   8.4   4.6
 26000 -34.6 -30.3  270  24 12   7.9   4.4 | -33.9 -29.0  270  20 11   8.2   4.5
 25000 -32.2 -26.0  275  22 11   8.0   4.4 | -31.5 -24.7  275  21 11   8.2   4.5
 24000 -29.8 -21.6  280  20 10   7.8   4.3 | -29.1 -20.4  280  21 11   8.0   4.4
 23000 -27.6 -17.7  280  19 10   7.7   4.2 | -26.7 -16.1  280  20 10   7.8   4.3
 22000 -25.3 -13.5  285  17  9   7.7   4.2 | -24.4 -11.9  285  20 10   7.8   4.3
 21000 -23.0  -9.4  285  16  8   6.9   3.8 | -22.1  -7.8  290  19 10   7.5   4.1
 20000 -21.0  -5.8  290  16  8   6.9   3.8 | -19.9  -3.8  290  18  9   7.5   4.1
 19500 -20.0  -4.0  290  16  8   6.9   3.8 | -18.8  -1.8  295  18  9   7.5   4.1
 19000 -18.9  -2.0  295  16  8   6.9   3.8 | -17.7   0.1  295  18  9   7.5   4.1
 18500 -17.9  -0.2  295  17  9   7.5   4.1 | -16.5   2.3  295  18  9   7.5   4.1
 18000 -16.7   1.9  300  16  8   7.8   4.3 | -15.4   4.3  300  17  9   7.5   4.1
 17500 -15.6   3.9  300  15  8   7.9   4.3 | -14.3   6.3  300  16  8   7.5   4.1
 17000 -14.3   6.3  300  15  8   8.9   4.9 | -13.2   8.2  305  15  8   7.5   4.1
 16500 -13.0   8.6  305  14  7   8.8   4.9 | -12.1  10.2  305  13  7   7.5   4.1
 16000 -11.6  11.1  305  13  7   9.4   5.1 | -11.0  12.2  310  11  6   7.7   4.2
 15500 -10.2  13.6  310  12  6   9.4   5.2 |  -9.3  15.3  315   8  4   7.8   4.3
 15000  -8.2  17.2  315  11  6   8.5   4.7 |  -8.2  17.2  320   6  3   7.2   3.9
 14500  -7.0  19.4  315  10  5   8.6   4.7 |  -7.1  19.2  330   4  2   7.2   3.9
 14000  -5.7  21.7  320   9  4   8.4   4.6 |  -6.0  21.2  345   2  1   7.9   4.3
 13500  -4.5  23.9  320   7  4   8.4   4.6 |  -4.8  23.4  020   1  0   8.0   4.4
 13000  -3.3  26.1  320   6  3   8.2   4.5 |  -3.6  25.5  110   1  1   8.3   4.5
 12500  -2.1  28.2  320   4  2   8.1   4.5 |  -2.4  27.7  135   2  1   8.4   4.6
 12000  -0.9  30.4  320   3  1   8.5   4.7 |  -1.2  29.8  145   4  2   8.6   4.7
 11500   0.4  32.7  320   1  1   8.7   4.8 |   0.1  32.2  145   4  2   8.8   4.8
 11000   1.7  35.1  000   0  0   8.1   4.4 |   1.4  34.5  145   4  2   8.2   4.5
 10500   2.8  37.0  145   1  1   7.2   4.0 |   2.5  36.5  145   4  2   6.9   3.8
 10250   3.3  37.9  140   2  1   9.5   5.2 |   3.1  37.6  150   3  2  10.7   5.8
 10000   4.1  39.4  145   2  1   9.9   5.4 |   4.0  39.2  150   3  2  10.9   6.0
  9750   4.7  40.5  145   2  1   8.0   4.4 |   4.6  40.3  155   3  1   7.3   4.0
  9500   5.3  41.5  150   1  1   8.5   4.7 |   5.2  41.4  165   3  1   8.1   4.5
  9250   5.8  42.4  160   1  1   8.6   4.7 |   5.8  42.4  175   2  1   8.2   4.5
  9000   6.5  43.7  160   1  0   9.3   5.1 |   6.4  43.5  185   2  1   7.9   4.3
  8750   7.1  44.8  175   1  0   9.7   5.3 |   6.9  44.4  215   2  1   7.3   4.0
  8500   7.8  46.0  185   1  0   9.4   5.1 |   7.5  45.5  235   3  1   7.3   4.0
  8250   8.5  47.3  205   1  0  10.3   5.7 |   8.0  46.4  250   3  2   7.8   4.3
  8000   9.3  48.7  210   1  0  10.8   5.9 |   8.7  47.7  255   5  2   7.9   4.4
  7750  10.1  50.2  225   1  0   9.7   5.3 |   9.2  48.6  260   7  3   6.3   3.5
  7500  10.8  51.4  235   1  0   9.2   5.0 |   9.6  49.3  260   8  4   5.7   3.1
  7250  11.5  52.7  245   1  0  10.1   5.6 |  10.1  50.2  260  10  5   5.7   3.1
  7000  12.3  54.1  250   1  0  10.9   6.0 |  10.5  50.9  255  12  6   5.3   2.9
  6750  13.0  55.4  260   1  0   9.8   5.4 |  10.8  51.4  255  14  7   4.6   2.5
  6500  13.8  56.8  270   1  1   9.7   5.3 |  11.1  52.0  255  16  8   3.9   2.1
  6250  14.5  58.1  275   1  1  10.7   5.9 |  11.4  52.5  250  17  9   4.0   2.2
  6000  15.3  59.5  280   1  1  11.6   6.4 |  11.5  52.7  250  16  8   4.0   2.2
  5750  16.1  61.0  280   1  1   9.1   5.0 |  11.7  53.1  250  15  8   5.2   2.9
  5500  16.8  62.2  285   1  1  11.8   6.5 |  12.2  54.0  250  14  7  10.5   5.8
________________________________________________________________________________

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.