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

000
UXUS97 KBOU 090153
SRGBOU

Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1853 MST Friday, December 8, 2017

This forecast is for Saturday, December 9, 2017:

If the trigger temperature of 57.3 F/14.1 C is reached...then
   Thermal Soaring Index....................... Good
   Maximum rate of lift........................ 557 ft/min (2.8 m/s)
   Maximum height of thermals.................. 12126 ft MSL (6819 ft AGL)

Forecast maximum temperature................... 61.0 F/16.6 C
Time of trigger temperature.................... 1230 MST
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 7329 ft MSL (2022 ft AGL)
Thermal soaring outlook for Sunday 12/10....... Fair

Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1700 MST)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1700 MST)................ Neither
Potential height of wave....................... 18834 ft MSL (13527 ft AGL)
Wave soaring outlook for Sunday 12/10.......... Poor

Remarks...

Sunrise/Sunset.................... 07:09:05 / 16:35:01 MST
Total possible sunshine........... 9 hr 25 min 55 sec (565 min 55 sec)
Altitude of sun at 11:52:07 MST... 27.41 degrees

Upper air data from numerical model forecast valid on 12/09/2017 at 0500 MST

Freezing level.................. 5348 ft MSL (41 ft AGL)
Additional freezing level....... 9954 ft MSL (4647 ft AGL)
Convective condensation level... 21782 ft MSL (16475 ft AGL)
Lifted condensation level....... 19395 ft MSL (14088 ft AGL)
Lifted index.................... +6.1
K index......................... -17.6

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  -61.2 -78.2   345   22   12  -1.6  -0.9      M     M       M      M    M
 45000  -63.8 -82.8   345   30   16  -1.4  -0.7      M     M       M      M    M
 40000  -63.6 -82.5   320   30   15   0.2   0.1      M     M       M      M    M
 38000  -61.9 -79.4   315   35   18   5.5   3.0      M     M       M      M    M
 36000  -58.6 -73.5   310   44   23   5.5   3.0      M     M       M      M    M
 34000  -55.0 -67.0   310   51   26   7.6   4.2      M     M       M      M    M
 32000  -50.5 -58.9   315   48   25   7.5   4.1      M     M       M      M    M
 30000  -45.3 -49.5   320   46   23   8.2   4.5   30.2  86.3    10.5      M    M
 29000  -42.9 -45.2   320   44   23   8.2   4.5   29.5  85.0    10.2      M    M
 28000  -40.4 -40.7   325   43   22   8.2   4.5   28.9  84.0     9.9      M    M
 27000  -38.0 -36.4   325   42   21   7.7   4.2   28.4  83.0     9.5      M    M
 26000  -35.7 -32.3   330   40   21   7.7   4.2   27.5  81.4     9.0      M    M
 25000  -33.4 -28.1   330   39   20   7.7   4.2   26.7  80.1     8.5      M    M
 24000  -31.1 -24.0   335   38   20   6.7   3.7   26.0  78.8     8.0      M    M
 23000  -29.2 -20.6   335   37   19   6.3   3.5   24.7  76.4     7.0      M    M
 22000  -27.3 -17.1   340   35   18   6.4   3.5   23.5  74.2     6.1      M    M
 21000  -25.3 -13.5   345   34   18   8.1   4.4   22.4  72.4     5.3      M    M
 20000  -22.9  -9.2   350   35   18   7.9   4.3   21.7  71.1     4.7      M    M
 19500  -21.7  -7.1   350   36   19   7.9   4.3   21.4  70.6     4.5      M    M
 19000  -20.5  -4.9   355   37   19   7.9   4.3   21.1  70.1     4.3      M    M
 18500  -19.3  -2.7   355   37   19   8.0   4.4   20.9  69.5     4.1      M    M
 18000  -18.1  -0.6   355   38   19   8.0   4.4   20.6  69.0     3.8      M    M
 17500  -16.9   1.6   355   38   20   8.0   4.4   20.3  68.5     3.6      M    M
 17000  -15.7   3.7   355   38   20   8.0   4.4   20.0  67.9     3.3      M    M
 16500  -14.5   5.9   360   38   20   7.9   4.4   19.7  67.4     3.1      M    M
 16000  -12.8   9.0   360   38   20   7.5   4.1   19.1  66.4     2.6      M    M
 15500  -11.7  10.9   360   38   20   7.5   4.1   18.7  65.7     2.3      M    M
 15000  -10.6  12.9   360   39   20   7.6   4.2   18.4  65.0     2.0      M    M
 14500   -9.5  14.9   360   39   20   7.6   4.2   18.0  64.4     1.7      M    M
 14000   -8.3  17.1   360   39   20   7.6   4.2   17.6  63.8     1.3      M    M
 13500   -7.2  19.0   360   38   20   7.6   4.2   17.3  63.1     1.0      M    M
 13000   -6.1  21.0   360   38   20   7.1   3.9   16.9  62.4     0.7      M    M
 12500   -5.0  23.0   360   38   20   7.2   3.9   16.5  61.6     0.3      M    M
 12000   -4.0  24.8   360   38   20   6.4   3.5   16.0  60.8    -0.2    541  2.8
 11500   -3.0  26.6   360   39   20   6.5   3.5   15.5  59.8    -0.7    498  2.5
 11000   -2.0  28.4   360   37   19   7.5   4.1   15.0  59.0    -1.1    452  2.3
 10500   -0.9  30.4   360   35   18   7.4   4.1   14.7  58.4    -1.5    404  2.1
 10250   -0.4  31.3   360   34   17   4.7   2.6   14.4  57.9    -1.7    383  1.9
 10000   -0.1  31.8   355   33   17   7.5   4.1   14.0  57.2    -2.1    365  1.9
  9750    0.7  33.3   355   31   16  12.2   6.7   14.1  57.4    -2.0    333  1.7
  9500    1.6  34.9   355   30   15  10.3   5.7   14.2  57.6    -1.9    300  1.5
  9250    2.3  36.1   350   29   15   8.2   4.5   14.2  57.5    -2.0    272  1.4
  9000    2.9  37.2   350   29   15   7.9   4.4   14.0  57.2    -2.1    247  1.3
  8750    3.5  38.3   350   29   15  10.0   5.5   14.0  57.1    -2.2    220  1.1
  8500    4.3  39.7   350   29   15   9.2   5.0   14.0  57.2    -2.2    190  1.0
  8250    4.9  40.8   350   28   14   7.5   4.1   13.8  56.9    -2.3    164  0.8
  8000    5.4  41.7   345   26   14   7.8   4.3   13.7  56.6    -2.5    140  0.7
  7750    6.0  42.8   345   25   13   8.2   4.5   13.6  56.4    -2.6    115  0.6
  7500    6.6  43.9   340   23   12   7.3   4.0   13.4  56.1    -2.8     90  0.5
  7250    7.1  44.8   340   22   11   5.6   3.1   13.1  55.7    -3.1     68  0.3
  7000    7.6  45.7   335   21   11   8.2   4.5   12.9  55.2    -3.3     47  0.2
  6750    8.0  46.4   330   20   10  -0.5  -0.3   12.6  54.7    -3.6     26  0.1
  6500    7.3  45.1   315   19   10 -13.4  -7.4   11.2  52.2    -5.0     38  0.2
  6250    6.3  43.3   305   20   10 -13.2  -7.3    9.4  49.0    -6.8     63  0.3
  6000    5.2  41.4   290   21   11 -16.0  -8.8    7.7  45.8    -8.6     87  0.4
  5750    3.7  38.7   280   17    9 -24.0 -13.2    5.4  41.8   -10.9    126  0.6
  5500    1.7  35.1   270   11    6 -27.9 -15.3    2.7  36.9   -13.7    179  0.9

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

           12/09/2017 at 0800 MST          |       12/09/2017 at 1100 MST
                                           |
K index... -16.2  LI... +4.3               | K index... -15.3  LI... +4.1
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 -60.6 -77.1  335  21 11  -1.5  -0.8 | -60.6 -77.1  345  21 11  -1.1  -0.6
 45000 -63.1 -81.6  335  26 13  -1.2  -0.6 | -62.2 -80.0  340  28 14  -0.8  -0.5
 40000 -61.9 -79.4  330  33 17   0.9   0.5 | -61.3 -78.3  345  32 17   0.7   0.4
 38000 -60.2 -76.4  330  35 18   4.7   2.6 | -59.8 -75.6  345  33 17   4.2   2.3
 36000 -57.4 -71.3  330  36 19   4.7   2.6 | -57.3 -71.1  345  32 17   4.2   2.3
 34000 -54.5 -66.1  330  37 19   6.0   3.3 | -54.1 -65.4  350  32 16   6.3   3.4
 32000 -50.5 -58.9  325  39 20   5.9   3.2 | -50.3 -58.5  355  34 17   6.3   3.5
 30000 -46.8 -52.2  325  40 20   6.9   3.8 | -46.4 -51.5  355  35 18   6.9   3.8
 29000 -44.7 -48.5  330  40 21   6.9   3.8 | -44.4 -47.9  355  35 18   6.9   3.8
 28000 -42.7 -44.9  330  40 21   6.9   3.8 | -42.3 -44.1  355  36 18   6.9   3.8
 27000 -40.5 -40.9  335  40 21   8.7   4.8 | -40.2 -40.4  355  36 18   7.6   4.2
 26000 -37.9 -36.2  335  39 20   8.8   4.8 | -37.9 -36.2  350  36 18   7.7   4.2
 25000 -35.2 -31.4  335  37 19   8.8   4.8 | -35.6 -32.1  345  35 18   7.7   4.2
 24000 -32.7 -26.9  340  35 18   7.3   4.0 | -33.2 -27.8  345  35 18   7.7   4.2
 23000 -30.6 -23.1  340  34 18   6.8   3.8 | -30.9 -23.6  345  33 17   7.7   4.2
 22000 -28.6 -19.5  345  34 17   6.8   3.8 | -28.6 -19.5  345  32 16   7.7   4.2
 21000 -26.4 -15.5  345  33 17   8.9   4.9 | -26.2 -15.2  340  30 16   8.2   4.5
 20000 -23.7 -10.7  350  33 17   8.7   4.8 | -23.8 -10.8  340  29 15   8.1   4.5
 19500 -22.4  -8.3  350  33 17   8.7   4.8 | -22.6  -8.7  340  28 15   8.1   4.5
 19000 -21.1  -6.0  350  34 17   8.7   4.8 | -21.4  -6.5  340  28 14   8.1   4.4
 18500 -19.8  -3.6  350  34 17   8.6   4.7 | -20.1  -4.2  340  27 14   8.6   4.7
 18000 -18.6  -1.5  350  34 17   8.6   4.7 | -18.2  -0.8  340  27 14   8.6   4.7
 17500 -17.3   0.9  350  34 17   8.4   4.6 | -16.9   1.6  340  27 14   8.9   4.9
 17000 -16.0   3.2  355  34 17   8.3   4.6 | -15.5   4.1  340  27 14   8.9   4.9
 16500 -14.2   6.4  355  34 17   8.3   4.5 | -14.2   6.4  340  27 14   8.4   4.6
 16000 -12.9   8.8  355  34 17   8.2   4.5 | -13.0   8.6  340  27 14   8.3   4.6
 15500 -11.7  10.9  355  34 17   8.0   4.4 | -11.7  10.9  340  27 14   8.1   4.4
 15000 -10.5  13.1  355  33 17   7.7   4.2 | -10.6  12.9  340  27 14   7.8   4.3
 14500  -9.4  15.1  355  33 17   7.7   4.2 |  -9.4  15.1  340  27 14   7.6   4.2
 14000  -8.2  17.2  355  33 17   7.5   4.1 |  -8.3  17.1  340  26 13   7.1   3.9
 13500  -7.1  19.2  355  33 17   7.5   4.1 |  -7.2  19.0  340  26 13   7.1   3.9
 13000  -6.0  21.2  355  33 17   7.2   4.0 |  -6.2  20.8  340  25 13   7.1   3.9
 12500  -4.9  23.2  355  33 17   7.2   4.0 |  -5.1  22.8  345  25 13   7.1   3.9
 12000  -3.9  25.0  360  33 17   6.7   3.7 |  -4.1  24.6  345  25 13   6.8   3.7
 11500  -2.9  26.8  360  32 17   6.8   3.7 |  -3.0  26.6  350  24 12   6.9   3.8
 11000  -1.8  28.8  360  32 16   7.7   4.2 |  -1.9  28.6  350  24 12   7.7   4.2
 10500  -0.7  30.7  360  31 16   7.6   4.1 |  -0.8  30.6  355  23 12   7.7   4.2
 10250  -0.1  31.8  360  31 16   5.9   3.3 |  -0.2  31.6  355  23 12   7.2   3.9
 10000   0.3  32.5  360  31 16   7.6   4.2 |   0.3  32.5  355  23 12   8.6   4.7
  9750   1.0  33.8  360  30 16  10.2   5.6 |   1.1  34.0  355  23 12  10.5   5.8
  9500   1.7  35.1  355  30 15   9.4   5.1 |   1.8  35.2  355  23 12   9.2   5.1
  9250   2.4  36.3  355  30 15   8.6   4.7 |   2.4  36.3  355  24 12   7.8   4.3
  9000   3.1  37.6  355  30 16   9.0   4.9 |   3.0  37.4  355  24 12   8.5   4.7
  8750   3.8  38.8  355  30 16  11.2   6.1 |   3.7  38.7  355  24 12  10.4   5.7
  8500   4.6  40.3  350  31 16   9.6   5.3 |   4.5  40.1  355  24 12   9.5   5.2
  8250   5.2  41.4  350  29 15   7.4   4.1 |   5.2  41.4  355  22 11   8.1   4.4
  8000   5.8  42.4  350  28 14   8.1   4.5 |   5.8  42.4  350  21 11   8.7   4.8
  7750   6.4  43.5  345  27 14   8.8   4.8 |   6.5  43.7  350  19 10   9.7   5.3
  7500   7.1  44.8  345  25 13   8.1   4.5 |   7.2  45.0  345  18  9   9.2   5.1
  7250   7.6  45.7  340  23 12   6.1   3.4 |   7.9  46.2  340  17  9   8.4   4.6
  7000   8.1  46.6  335  22 11   9.4   5.2 |   8.5  47.3  335  15  8   8.4   4.6
  6750   8.7  47.7  330  20 10  -1.8  -1.0 |   8.9  48.0  325  15  8   1.5   0.8
  6500   7.8  46.0  320  21 11 -12.8  -7.0 |   8.7  47.7  315  14  7  -3.2  -1.7
  6250   7.1  44.8  305  21 11  -5.6  -3.1 |   8.6  47.5  300  14  7  -1.7  -0.9
  6000   6.5  43.7  295  22 12 -18.5 -10.2 |   8.4  47.1  285  14  7  -2.6  -1.4
  5750   4.3  39.7  285  17  9 -33.9 -18.6 |   8.2  46.8  280  11  6   1.8   1.0
  5500   1.9  35.4  270  11  6 -24.6 -13.5 |   8.7  47.7  275   9  4  10.5   5.8

           12/09/2017 at 1400 MST          |       12/09/2017 at 1700 MST
                                           |
K index... -25.3  LI... +4.4               | K index... -24.2  LI... +5.2
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 -60.4 -76.7  350  18  9  -0.8  -0.4 | -60.1 -76.2  340  15  8  -0.5  -0.3
 45000 -61.6 -78.9  350  25 13  -0.7  -0.4 | -60.9 -77.6  340  18  9  -0.6  -0.3
 40000 -61.5 -78.7  345  29 15   0.1   0.1 | -62.0 -79.6  335  30 15  -0.7  -0.4
 38000 -60.4 -76.7  350  32 16   3.8   2.1 | -61.1 -78.0  340  34 18   4.1   2.2
 36000 -57.8 -72.0  355  36 18   3.8   2.1 | -58.3 -72.9  355  41 21   4.1   2.2
 34000 -54.9 -66.8  360  39 20   7.3   4.0 | -55.2 -67.4  360  45 23   7.6   4.2
 32000 -50.5 -58.9  005  40 21   7.4   4.1 | -50.6 -59.1  355  45 23   7.7   4.2
 30000 -46.0 -50.8  005  41 21   7.9   4.3 | -45.9 -50.6  355  45 23   8.1   4.4
 29000 -43.6 -46.5  005  41 21   7.9   4.3 | -43.5 -46.3  355  43 22   8.1   4.4
 28000 -41.2 -42.2  010  41 21   7.9   4.3 | -41.0 -41.8  355  41 21   8.1   4.4
 27000 -38.9 -38.0  010  41 21   7.5   4.1 | -38.6 -37.5  355  40 21   7.7   4.2
 26000 -36.6 -33.9  005  39 20   7.4   4.1 | -36.3 -33.3  355  38 20   7.7   4.2
 25000 -34.4 -29.9  005  37 19   7.4   4.1 | -34.0 -29.2  355  37 19   7.7   4.2
 24000 -32.2 -26.0  005  36 19   7.5   4.1 | -31.7 -25.1  350  36 18   7.8   4.3
 23000 -29.9 -21.8  360  35 18   7.5   4.1 | -29.3 -20.7  350  36 19   7.9   4.3
 22000 -27.6 -17.7  355  34 17   7.5   4.1 | -27.0 -16.6  350  36 19   7.9   4.3
 21000 -25.4 -13.7  355  32 17   7.6   4.1 | -24.6 -12.3  350  36 19   8.0   4.4
 20000 -23.1  -9.6  345  30 16   7.6   4.1 | -22.2  -8.0  345  35 18   8.0   4.4
 19500 -22.0  -7.6  345  29 15   7.5   4.1 | -21.0  -5.8  345  35 18   8.0   4.4
 19000 -20.8  -5.4  340  28 15   7.5   4.1 | -19.8  -3.6  345  34 18   8.1   4.4
 18500 -19.0  -2.2  340  27 14   8.2   4.5 | -18.1  -0.6  345  33 17   7.2   3.9
 18000 -17.8  -0.0  335  27 14   8.2   4.5 | -17.0   1.4  340  32 17   7.2   3.9
 17500 -16.6   2.1  335  27 14   7.9   4.3 | -15.9   3.4  340  31 16   7.1   3.9
 17000 -15.4   4.3  335  27 14   7.9   4.4 | -14.9   5.2  340  31 16   7.1   3.9
 16500 -14.2   6.4  335  27 14   7.8   4.3 | -13.8   7.2  335  30 15   7.3   4.0
 16000 -13.1   8.4  335  27 14   7.7   4.2 | -12.7   9.1  335  29 15   7.4   4.1
 15500 -11.9  10.6  330  27 14   7.7   4.2 | -11.6  11.1  335  29 15   7.1   3.9
 15000 -10.7  12.7  330  26 13   7.7   4.2 | -10.6  12.9  335  28 14   6.8   3.7
 14500  -9.6  14.7  330  26 13   7.7   4.2 |  -9.5  14.9  335  27 14   7.0   3.8
 14000  -8.5  16.7  330  25 13   7.6   4.2 |  -8.4  16.9  335  26 14   7.9   4.3
 13500  -7.3  18.9  330  24 13   7.6   4.2 |  -7.2  19.0  335  26 13   7.8   4.3
 13000  -6.2  20.8  330  23 12   7.6   4.2 |  -6.1  21.0  335  25 13   7.5   4.1
 12500  -5.0  23.0  330  22 11   7.6   4.2 |  -5.0  23.0  335  23 12   7.6   4.2
 12000  -3.9  25.0  330  21 11   7.4   4.1 |  -3.8  25.2  340  22 11   8.2   4.5
 11500  -2.8  27.0  335  20 10   7.5   4.1 |  -2.5  27.5  340  21 11   8.2   4.5
 11000  -1.6  29.1  335  19 10   8.1   4.4 |  -1.3  29.7  340  19 10   8.0   4.4
 10500  -0.4  31.3  335  17  9   7.9   4.3 |  -0.1  31.8  340  17  9   7.8   4.3
 10250   0.1  32.2  335  17  9   6.1   3.4 |   0.4  32.7  340  16  8   5.6   3.0
 10000   0.6  33.1  335  17  9   8.1   4.4 |   0.8  33.4  340  16  8   8.5   4.7
  9750   1.3  34.3  335  15  8  10.8   5.9 |   1.7  35.1  340  15  7  12.9   7.1
  9500   2.1  35.8  335  14  7   9.3   5.1 |   2.6  36.7  340  13  7   9.7   5.3
  9250   2.7  36.9  335  13  7   8.1   4.4 |   3.1  37.6  335  13  7   6.5   3.6
  9000   3.3  37.9  335  12  6   8.8   4.8 |   3.6  38.5  335  13  7   7.0   3.9
  8750   4.1  39.4  330  11  6  10.9   6.0 |   4.2  39.6  325  14  7   9.2   5.1
  8500   4.9  40.8  330  10  5  10.0   5.5 |   4.9  40.8  320  15  8   8.3   4.5
  8250   5.6  42.1  320  10  5   8.4   4.6 |   5.5  41.9  315  16  8   6.7   3.7
  8000   6.2  43.2  315  10  5   9.2   5.0 |   6.0  42.8  310  18  9   7.2   4.0
  7750   6.9  44.4  305  10  5   9.9   5.4 |   6.5  43.7  305  19 10   7.0   3.8
  7500   7.7  45.9  300   9  5   8.7   4.8 |   7.0  44.6  305  20 10   6.2   3.4
  7250   8.2  46.8  295  10  5   7.6   4.2 |   7.4  45.3  300  20 10   5.7   3.1
  7000   8.8  47.8  290  10  5   8.3   4.5 |   7.8  46.0  300  21 11   6.1   3.4
  6750   9.4  48.9  285  10  5   7.2   3.9 |   8.3  46.9  300  21 11   7.3   4.0
  6500   9.9  49.8  285   9  4   6.3   3.4 |   8.9  48.0  300  20 10   8.0   4.4
  6250  10.3  50.5  280   7  4   6.1   3.4 |   9.5  49.1  300  18  9   7.5   4.1
  6000  10.8  51.4  280   6  3   7.8   4.3 |  10.0  50.0  305  17  9   8.6   4.7
  5750  11.5  52.7  275   6  3  11.1   6.1 |  10.6  51.1  305  14  7   1.9   1.0
  5500  12.4  54.3  275   5  3  11.5   6.3 |  10.1  50.2  305  10  5 -12.0  -6.6
________________________________________________________________________________

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.