Soaring Guidance
Issued by NWS Grand Junction, CO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9
000
UXUS97 KGJT 131318
SRGGJT

Soaring Forecast
National Weather Service Grand Junction, Colorado
0618 MST Wednesday, December 13, 2017

This forecast is for Wednesday, December 13, 2017:

If the trigger temperature of 62.7 F/17.1 C is reached...then
   Thermal Soaring Index....................... Fair
   Maximum rate of lift........................ 242 ft/min (1.2 m/s)
   Maximum height of thermals.................. 7196 ft MSL (2357 ft AGL)

Forecast maximum temperature................... 52.0 F/11.6 C
Time of trigger temperature.................... None
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................. 6253 ft MSL (1414 ft AGL)
Thermal soaring outlook for Thursday 12/14..... Good

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

Remarks...

Sunrise/Sunset.................... 07:24:56 / 16:52:13 MST
Total possible sunshine........... 9 hr 27 min 16 sec (567 min 16 sec)
Altitude of sun at 12:08:37 MST... 27.76 degrees

Upper air data from rawinsonde observation taken on 12/13/2017 at 0500 MST

Freezing level.................. 5183 ft MSL (344 ft AGL)
Additional freezing level....... 11423 ft MSL (6584 ft AGL)
Convective condensation level... 21932 ft MSL (17093 ft AGL)
Lifted condensation level....... 14656 ft MSL (9816 ft AGL)
Lifted index.................... +14.4
K index......................... -34.0

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  -62.3 -80.1   335   21   11  -0.1  -0.0   97.8 208.0    49.3      M    M
 45000  -63.3 -81.9   315   35   18  -0.0  -0.0   70.3 158.5    36.2      M    M
 40000  -63.8 -82.8   025   26   14   8.1   4.4   46.5 115.6    23.2      M    M
 38000  -62.1 -79.8   005   39   20   4.0   2.2   40.2 104.4    19.6      M    M
 36000  -56.8 -70.2   010   33   17   8.9   4.9   39.5 103.0    19.6      M    M
 34000  -51.5 -60.7   010   28   14   8.4   4.6   38.6 101.5    19.6      M    M
 32000  -45.5 -49.9   015   25   13   9.3   5.1   37.8 100.0    19.5      M    M
 30000  -40.2 -40.4   015   15    8   9.4   5.2   37.1  98.8    19.5      M    M
 29000  -37.5 -35.5   360   17    9   9.3   5.1   36.9  98.5    19.6      M    M
 28000  -34.9 -30.8   350   20   10   7.9   4.3   36.4  97.6    19.5      M    M
 27000  -32.8 -27.0   345   23   12   7.1   3.9   35.4  95.8    18.9      M    M
 26000  -30.4 -22.7   340   26   14   8.5   4.7   34.7  94.5    18.6      M    M
 25000  -28.1 -18.6   335   30   15   8.4   4.6   34.0  93.2    18.2      M    M
 24000  -25.5 -13.9   330   34   18   7.8   4.3   33.6  92.4    18.1      M    M
 23000  -23.5 -10.3   335   34   18   6.4   3.5   32.4  90.3    17.4      M    M
 22000  -21.6  -6.9   335   35   18   6.7   3.7   31.2  88.2    16.6      M    M
 21000  -18.8  -1.8   335   35   18   9.9   5.4   31.1  88.0    16.6      M    M
 20000  -15.9   3.4   340   36   19   9.4   5.2   31.1  88.0    16.9      M    M
 19500  -15.3   4.5   340   35   18  -1.0  -0.5   30.1  86.2    16.1      M    M
 19000  -14.7   5.5   345   34   17   7.1   3.9   29.1  84.4    15.3      M    M
 18500  -13.7   7.3   345   32   16   7.4   4.1   28.6  83.4    15.0      M    M
 18000  -12.7   9.1   340   31   16   5.2   2.9   28.0  82.4    14.6      M    M
 17500  -11.9  10.6   340   29   15   6.4   3.5   27.2  81.0    14.0      M    M
 17000  -10.2  13.6   330   27   14   7.3   4.0   26.6  79.9    13.6      M    M
 16500   -9.1  15.6   330   26   13   7.3   4.0   26.2  79.2    13.3      M    M
 16000   -8.1  17.4   325   25   13   7.3   4.0   25.8  78.5    13.0      M    M
 15500   -7.0  19.4   330   25   13   7.3   4.0   25.4  77.7    12.7      M    M
 15000   -5.9  21.4   335   25   13   7.3   4.0   24.9  76.9    12.4      M    M
 14500   -4.8  23.4   340   26   13   7.3   4.0   24.5  76.2    12.1      M    M
 14000   -3.7  25.3   345   26   13   7.3   4.0   24.2  75.5    11.8      M    M
 13500   -2.6  27.3   350   25   13   6.7   3.7   23.7  74.7    11.5      M    M
 13000   -1.9  28.6   350   23   12   3.5   1.9   22.9  73.2    10.8      M    M
 12500   -1.4  29.5   340   18    9   3.8   2.1   21.9  71.4     9.9      M    M
 12000   -0.8  30.6   320   14    7   3.9   2.2   21.0  69.7     9.0      M    M
 11500   -0.1  31.8   310   12    6   7.1   3.9   20.2  68.4     8.3      M    M
 11000    1.0  33.8   295   11    6   7.3   4.0   19.8  67.7     8.0      M    M
 10500    1.9  35.4   280    9    4   9.0   4.9   19.4  66.9     7.5      M    M
 10250    2.6  36.7   270    8    4   8.5   4.7   19.4  66.9     7.5      M    M
 10000    3.1  37.6   270    8    4   4.9   2.7   19.1  66.4     7.3      M    M
  9750    3.5  38.3   265    9    5   5.5   3.0   18.8  65.8     7.0      M    M
  9500    3.9  39.0   265    9    5   5.3   2.9   18.4  65.1     6.6      M    M
  9250    4.3  39.7   260   10    5   5.4   3.0   18.1  64.5     6.3      M    M
  9000    4.6  40.3   260   10    5   5.0   2.7   17.7  63.9     5.9      M    M
  8750    5.0  41.0   260    8    4   4.2   2.3   17.3  63.1     5.6      M    M
  8500    5.4  41.7   255    6    3   5.5   3.0   16.9  62.4     5.3      M    M
  8250    5.7  42.3   245    4    2   1.2   0.7   16.5  61.7     4.9      M    M
  8000    5.6  42.1   215    2    1  -4.0  -2.2   15.5  60.0     4.0      M    M
  7750    5.3  41.5   180    4    2  -3.5  -1.9   14.5  58.1     3.0      M    M
  7500    5.0  41.0   165    7    3  -4.0  -2.2   13.5  56.3     2.0      M    M
  7250    4.5  40.1   165   10    5 -12.7  -7.0   12.2  53.9     0.8      M    M
  7000    3.4  38.1   160   12    6 -10.4  -5.7   10.3  50.6    -1.1    257  1.3
  6750    3.2  37.8   160   13    6   2.7   1.5    9.4  48.8    -2.0    255  1.3
  6500    3.5  38.3   160   12    6   3.8   2.1    8.9  48.0    -2.4    239  1.2
  6250    3.8  38.8   155   12    6   5.4   3.0    8.5  47.2    -2.9    223  1.1
  6000    4.1  39.4   155   11    6  -2.0  -1.1    8.0  46.5    -3.3    207  1.1
  5750    3.2  37.8   155   11    6 -20.7 -11.3    6.4  43.5    -4.9    226  1.1
  5500    1.7  35.1   150   12    6  -9.4  -5.1    4.2  39.5    -7.2    263  1.3
  5250    1.5  34.7   150   12    6 -11.0  -6.0    3.2  37.7    -8.2    263  1.3
  5000   -1.0  30.2   150   13    7 -54.6 -30.0    0.0  32.0   -11.3    328  1.7

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

           12/13/2017 at 0800 MST          |       12/13/2017 at 1100 MST
                                           |
K index... -17.4  LI... +6.8               | K index... -0.9  LI... +8.5
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  310  25 13   0.8   0.5 | -61.4 -78.5  320  28 14   1.3   0.7
 45000 -59.5 -75.1  315  32 16  -1.9  -1.0 | -59.6 -75.3  330  35 18  -2.4  -1.3
 40000 -63.5 -82.3  010  35 18  -2.2  -1.2 | -62.7 -80.9  360  36 18  -1.8  -1.0
 38000 -60.3 -76.5  015  31 16   7.7   4.2 | -59.8 -75.6  360  31 16   7.7   4.2
 36000 -55.7 -68.3  010  24 13   7.7   4.2 | -55.2 -67.4  350  25 13   7.7   4.2
 34000 -50.8 -59.4  005  21 11   8.6   4.7 | -50.5 -58.9  340  22 11   7.9   4.3
 32000 -45.6 -50.1  005  22 11   8.6   4.7 | -45.8 -50.4  335  22 12   7.9   4.3
 30000 -40.4 -40.7  360  23 12   8.7   4.8 | -40.2 -40.4  335  25 13   8.9   4.9
 29000 -37.8 -36.0  355  25 13   8.7   4.8 | -37.6 -35.7  330  27 14   8.9   4.9
 28000 -35.2 -31.4  350  26 13   8.7   4.8 | -34.9 -30.8  330  29 15   8.9   4.9
 27000 -32.7 -26.9  345  28 14   8.1   4.4 | -32.4 -26.3  330  30 15   7.9   4.3
 26000 -30.2 -22.4  345  29 15   8.1   4.5 | -30.0 -22.0  335  31 16   7.9   4.4
 25000 -27.8 -18.0  340  31 16   8.2   4.5 | -27.6 -17.7  335  31 16   8.0   4.4
 24000 -25.4 -13.7  340  33 17   7.4   4.1 | -25.3 -13.5  335  31 16   7.3   4.0
 23000 -23.2  -9.8  340  34 17   7.4   4.0 | -23.1  -9.6  340  30 16   7.4   4.1
 22000 -20.5  -4.9  335  35 18   7.4   4.1 | -20.9  -5.6  340  29 15   7.4   4.1
 21000 -18.4  -1.1  335  35 18   6.7   3.7 | -18.8  -1.8  345  28 15   6.8   3.7
 20000 -16.4   2.5  335  34 17   6.7   3.7 | -16.8   1.8  345  28 14   6.9   3.8
 19500 -15.4   4.3  335  33 17   6.7   3.7 | -15.8   3.6  345  28 14   6.9   3.8
 19000 -14.4   6.1  335  32 17   6.7   3.7 | -14.8   5.4  345  28 14   7.1   3.9
 18500 -13.4   7.9  335  31 16   6.7   3.7 | -13.9   7.0  345  27 14   4.6   2.5
 18000 -12.4   9.7  335  30 16   6.8   3.7 | -12.9   8.8  340  27 14   4.3   2.4
 17500 -11.3  11.7  335  29 15   6.2   3.4 | -12.0  10.4  340  27 14   8.6   4.7
 17000 -10.4  13.3  335  28 15   6.3   3.4 | -10.7  12.7  340  26 13   8.3   4.6
 16500  -9.4  15.1  335  28 14   6.1   3.4 |  -9.5  14.9  340  25 13   7.5   4.1
 16000  -8.5  16.7  335  26 14   6.0   3.3 |  -8.4  16.9  335  24 12   6.9   3.8
 15500  -7.5  18.5  335  25 13   5.9   3.2 |  -7.3  18.9  335  23 12   6.7   3.7
 15000  -6.8  19.8  335  24 12   4.8   2.6 |  -6.4  20.5  335  22 11   5.9   3.2
 14500  -6.0  21.2  335  22 11   4.9   2.7 |  -5.4  22.3  335  21 11   6.2   3.4
 14000  -5.3  22.5  335  20 10   4.6   2.5 |  -4.5  23.9  330  19 10   5.0   2.8
 13500  -4.7  23.5  340  17  9   4.6   2.5 |  -3.7  25.3  330  17  9   5.3   2.9
 13000  -3.9  25.0  345  15  8   5.4   3.0 |  -3.0  26.6  330  15  8   3.8   2.1
 12500  -3.2  26.2  350  13  7   5.6   3.1 |  -2.4  27.7  325  13  6   3.7   2.0
 12000  -2.3  27.9  350  11  6   6.4   3.5 |  -1.8  28.8  325  10  5   4.7   2.6
 11500  -1.4  29.5  355  10  5   6.6   3.6 |  -1.2  29.8  325   7  4   4.9   2.7
 11000  -0.5  31.1  355   9  5   6.7   3.7 |  -0.4  31.3  320   5  2   6.0   3.3
 10500   0.5  32.9  360   9  4   7.1   3.9 |   0.4  32.7  330   3  2   6.9   3.8
 10250   1.0  33.8  360   8  4   4.9   2.7 |   0.9  33.6  335   3  1   3.3   1.8
 10000   1.3  34.3  360   8  4   4.0   2.2 |   1.0  33.8  345   2  1   3.6   2.0
  9750   1.7  35.1  360   8  4   5.6   3.1 |   1.5  34.7  005   2  1   7.2   3.9
  9500   2.1  35.8  360   7  4   5.9   3.2 |   1.9  35.4  020   2  1   6.7   3.7
  9250   2.5  36.5  005   7  4   4.7   2.6 |   2.4  36.3  030   3  1   5.2   2.9
  9000   2.8  37.0  005   6  3   3.3   1.8 |   2.7  36.9  040   3  1   3.5   1.9
  8750   3.1  37.6  005   6  3   3.6   2.0 |   3.0  37.4  045   3  1   4.2   2.3
  8500   3.4  38.1  010   5  3   3.3   1.8 |   3.3  37.9  055   3  1   4.1   2.2
  8250   3.6  38.5  015   4  2   1.8   1.0 |   3.6  38.5  060   3  1   2.9   1.6
  8000   3.7  38.7  020   4  2   0.8   0.5 |   3.8  38.8  065   3  1   2.2   1.2
  7750   3.8  38.8  035   3  2   0.9   0.5 |   4.0  39.2  070   2  1   2.2   1.2
  7500   3.8  38.8  050   2  1   0.6   0.3 |   4.1  39.4  080   2  1   1.3   0.7
  7250   3.9  39.0  070   2  1   0.5   0.3 |   4.2  39.6  095   2  1   0.4   0.2
  7000   3.9  39.0  085   2  1   0.6   0.3 |   4.2  39.6  115   1  1   0.9   0.5
  6750   3.9  39.0  105   2  1   0.1   0.1 |   4.2  39.6  135   1  1  -1.2  -0.6
  6500   3.9  39.0  115   2  1  -1.0  -0.6 |   4.1  39.4  150   2  1   0.8   0.5
  6250   3.8  38.8  115   3  2  -2.6  -1.4 |   4.4  39.9  155   2  1   4.7   2.6
  6000   3.6  38.5  110   4  2   1.3   0.7 |   4.7  40.5  160   2  1   2.6   1.4
  5750   3.3  37.9  110   5  2 -19.4 -10.6 |   4.9  40.8  165   2  1   7.3   4.0
  5500   0.2  32.4  100   4  2 -61.2 -33.6 |   5.9  42.6  165   1  1  18.5  10.1
  5250     M     M    M   M  M     M     M |     M     M    M   M  M     M     M
  5000     M     M    M   M  M     M     M |     M     M    M   M  M     M     M

           12/13/2017 at 1400 MST          |       12/13/2017 at 1700 MST
                                           |
K index... +2.1  LI... +7.5                | K index... +5.3  LI... +7.2
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 -61.1 -78.0  330  28 15   1.1   0.6 | -60.7 -77.3  340  27 14   0.6   0.3
 45000 -59.4 -74.9  345  37 19  -0.8  -0.4 | -59.8 -75.6  355  30 16  -0.2  -0.1
 40000 -62.0 -79.6  335  33 17  -1.4  -0.8 | -60.8 -77.4  295  31 16  -0.6  -0.3
 38000 -59.3 -74.7  330  30 15   7.0   3.8 | -58.6 -73.5  290  35 18   5.8   3.2
 36000 -55.1 -67.2  320  27 14   7.0   3.8 | -55.1 -67.2  295  39 20   5.8   3.2
 34000 -50.6 -59.1  315  26 14   8.1   4.4 | -51.2 -60.2  295  41 21   8.0   4.4
 32000 -45.8 -50.4  315  28 14   8.1   4.4 | -46.5 -51.7  295  41 21   8.0   4.4
 30000 -40.8 -41.4  315  30 15   8.7   4.8 | -41.5 -42.7  300  40 21   8.8   4.8
 29000 -38.2 -36.8  320  31 16   8.7   4.8 | -38.9 -38.0  300  38 20   8.7   4.8
 28000 -35.6 -32.1  320  32 16   8.7   4.8 | -36.3 -33.3  305  37 19   8.8   4.8
 27000 -32.5 -26.5  325  33 17   8.0   4.4 | -33.7 -28.7  305  35 18   8.3   4.6
 26000 -30.1 -22.2  330  33 17   8.0   4.4 | -30.7 -23.3  310  32 16   8.2   4.5
 25000 -27.7 -17.9  330  32 17   8.0   4.4 | -28.3 -18.9  310  29 15   8.2   4.5
 24000 -25.4 -13.7  330  32 16   7.3   4.0 | -25.9 -14.6  315  27 14   7.1   3.9
 23000 -23.2  -9.8  330  30 15   7.4   4.0 | -23.8 -10.8  310  27 14   7.1   3.9
 22000 -21.1  -6.0  330  28 14   7.4   4.0 | -21.7  -7.1  310  27 14   7.1   3.9
 21000 -19.0  -2.2  330  26 13   6.4   3.5 | -19.7  -3.5  310  26 14   6.6   3.6
 20000 -17.1   1.2  330  24 12   6.5   3.6 | -17.8  -0.0  305  25 13   6.6   3.6
 19500 -16.1   3.0  330  23 12   6.5   3.6 | -16.8   1.8  305  25 13   6.6   3.6
 19000 -15.2   4.6  330  22 11   6.6   3.6 | -15.8   3.6  300  24 12   6.7   3.7
 18500 -14.3   6.3  330  21 11   5.6   3.1 | -14.9   5.2  300  24 12   6.4   3.5
 18000 -13.5   7.7  325  21 11   5.8   3.2 | -13.9   7.0  300  23 12   6.4   3.5
 17500 -12.7   9.1  320  20 10   6.7   3.6 | -13.0   8.6  300  23 12   6.4   3.5
 17000 -11.5  11.3  320  20 10   7.6   4.2 | -12.0  10.4  300  23 12   6.6   3.6
 16500 -10.4  13.3  320  20 10   7.6   4.2 | -11.1  12.0  300  23 12   6.5   3.6
 16000  -9.3  15.3  320  19 10   6.7   3.7 | -10.1  13.8  300  22 12   7.4   4.1
 15500  -8.3  17.1  320  19 10   6.8   3.7 |  -9.0  15.8  300  22 11   7.4   4.0
 15000  -7.2  19.0  320  18  9   7.4   4.1 |  -7.9  17.8  300  22 11   7.8   4.3
 14500  -6.0  21.2  320  17  9   7.5   4.1 |  -6.6  20.1  300  21 11   7.9   4.3
 14000  -4.9  23.2  315  17  9   6.4   3.5 |  -5.4  22.3  295  20 10   7.1   3.9
 13500  -3.5  25.7  310  15  8   6.0   3.3 |  -4.4  24.1  295  19 10   6.0   3.3
 13000  -2.7  27.1  305  14  7   4.1   2.2 |  -3.0  26.6  290  17  9   4.6   2.5
 12500  -2.0  28.4  300  12  6   4.2   2.3 |  -2.3  27.9  285  16  8   4.5   2.5
 12000  -1.3  29.7  290  11  6   5.2   2.9 |  -1.6  29.1  280  15  8   4.6   2.5
 11500  -0.5  31.1  285  10  5   5.3   2.9 |  -0.9  30.4  275  14  7   4.6   2.5
 11000   0.2  32.4  275   8  4   5.3   2.9 |  -0.2  31.6  275  13  7   4.6   2.5
 10500   1.0  33.8  275   7  4   5.9   3.3 |   0.5  32.9  275  12  6   5.1   2.8
 10250   1.3  34.3  270   6  3   3.2   1.8 |   0.8  33.4  270  11  6   2.8   1.6
 10000   1.5  34.7  270   6  3   3.2   1.8 |   0.9  33.6  270  11  5   3.0   1.7
  9750   1.9  35.4  270   5  3   5.8   3.2 |   1.3  34.3  270  10  5   5.4   2.9
  9500   2.2  36.0  270   4  2   5.6   3.1 |   1.6  34.9  265   9  5   4.8   2.7
  9250   2.6  36.7  270   3  2   4.0   2.2 |   1.9  35.4  265   8  4   4.8   2.7
  9000   2.8  37.0  270   3  1   3.2   1.8 |   2.3  36.1  265   7  4   4.8   2.6
  8750   3.1  37.6  275   2  1   4.5   2.5 |   2.6  36.7  260   7  3   5.0   2.7
  8500   3.4  38.1  280   2  1   4.1   2.3 |   3.0  37.4  255   6  3   4.9   2.7
  8250   3.8  38.8  285   1  1   3.9   2.1 |   3.4  38.1  250   5  3   4.9   2.7
  8000   4.0  39.2  295   1  0   3.6   2.0 |   3.7  38.7  245   5  2   4.6   2.5
  7750   4.3  39.7  295   1  0   3.7   2.0 |   4.1  39.4  245   4  2   4.3   2.3
  7500   4.6  40.3  000   0  0   3.0   1.7 |   4.4  39.9  240   4  2   3.9   2.1
  7250   4.8  40.6  290   1  0   2.3   1.3 |   4.7  40.5  240   3  2   3.2   1.8
  7000   4.9  40.8  295   1  1   1.9   1.1 |   4.9  40.8  245   3  2   2.9   1.6
  6750   5.1  41.2  300   2  1   2.4   1.3 |   5.1  41.2  255   3  2   1.7   0.9
  6500   5.4  41.7  305   2  1   7.3   4.0 |   5.2  41.4  265   3  2   3.8   2.1
  6250   6.1  43.0  300   3  1  10.3   5.6 |   5.6  42.1  270   3  2   5.7   3.1
  6000   6.8  44.2  300   3  1   9.1   5.0 |   6.0  42.8  275   4  2   6.4   3.5
  5750   7.5  45.5  300   3  1   9.0   4.9 |   6.5  43.7  275   4  2   4.0   2.2
  5500   8.2  46.8  300   3  1   9.2   5.1 |   6.5  43.7  275   4  2  -1.6  -0.9
  5250   8.9  48.0  300   3  1   9.0   5.0 |   6.4  43.5  275   3  2  -1.4  -0.8
  5000     M     M    M   M  M     M     M |     M     M    M   M  M     M     M
________________________________________________________________________________

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

The information contained herein is based on rawinsonde observation and/or
numerical weather prediction model data taken at Walker Field in Grand
Junction, Colorado at

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

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

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

DEFINITIONS:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

042613



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