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
000
UXUS97 KGJT 241220
SRGGJT

Soaring Forecast
National Weather Service Grand Junction, Colorado
0620 MDT Tuesday, April 24, 2018

This forecast is for Tuesday, April 24, 2018:

If the trigger temperature of 63.3 F/17.4 C is reached...then
   Thermal Soaring Index....................... Good
   Maximum rate of lift........................ 494 ft/min (2.5 m/s)
   Maximum height of thermals.................. 11516 ft MSL (6677 ft AGL)

Forecast maximum temperature................... 69.0 F/21.0 C
Time of trigger temperature.................... 1145 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................. 8891 ft MSL (4052 ft AGL)
Thermal soaring outlook for Wednesday 04/25.... Excellent

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

Remarks...

Sunrise/Sunset.................... 06:24:47 / 19:59:28 MDT
Total possible sunshine........... 13 hr 34 min 41 sec (814 min 41 sec)
Altitude of sun at 13:12:17 MDT... 63.92 degrees

Upper air data from rawinsonde observation taken on 04/24/2018 at 0600 MDT

Freezing level.................. 11681 ft MSL (6842 ft AGL)
Convective condensation level... 14965 ft MSL (10126 ft AGL)
Lifted condensation level....... 14523 ft MSL (9683 ft AGL)
Lifted index.................... +0.6
K index......................... +19.3

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  -60.3 -76.5   280   39   20   4.6   2.5   99.7 211.5    45.2      M    M
 45000  -59.1 -74.4   285   40   20   0.7   0.4   77.0 170.7    34.5      M    M
 40000  -61.7 -79.1   280   61   31   6.9   3.8   49.9 121.7    19.2      M    M
 38000  -57.5 -71.5   285   63   32   6.6   3.6   47.1 116.8    17.9      M    M
 36000  -53.5 -64.3   285   67   35   6.6   3.6   44.3 111.8    16.5      M    M
 34000  -49.1 -56.4   285   71   37   5.8   3.2   41.5 106.7    14.9      M    M
 32000  -45.0 -49.0   285   70   36   8.2   4.5   39.1 102.3    13.5      M    M
 30000  -40.0 -40.0   285   65   33   8.4   4.6   38.0 100.3    13.1      M    M
 29000  -37.5 -35.5   280   62   32   7.4   4.1   37.4  99.4    12.8      M    M
 28000  -35.6 -32.1   280   59   30   6.4   3.5   36.0  96.9    11.9      M    M
 27000  -33.7 -28.7   275   56   29   6.4   3.5   34.8  94.7    11.1      M    M
 26000  -32.0 -25.6   270   53   27   5.4   2.9   33.2  91.8    10.0      M    M
 25000  -30.8 -23.4   265   51   26   2.1   1.2   31.0  87.8     8.3      M    M
 24000  -29.6 -21.3   260   47   24   8.5   4.7   29.0  84.2     6.7      M    M
 23000  -26.9 -16.4   260   45   23   9.3   5.1   28.7  83.7     6.5      M    M
 22000  -24.6 -12.3   260   42   22   7.3   4.0   27.9  82.2     5.9      M    M
 21000  -22.5  -8.5   260   40   21   7.3   4.0   27.1  80.7     5.3      M    M
 20000  -20.1  -4.2   265   42   21   6.7   3.7   26.4  79.6     4.8      M    M
 19500  -19.2  -2.6   265   43   22   7.1   3.9   25.8  78.4     4.3      M    M
 19000  -17.4   0.7   270   44   23   7.6   4.2   25.3  77.6     3.9      M    M
 18500  -16.4   2.5   270   45   23   7.8   4.3   24.8  76.7     3.4      M    M
 18000  -15.1   4.8   270   44   23   8.9   4.9   24.7  76.5     3.3      M    M
 17500  -13.8   7.2   270   42   22   8.8   4.8   24.5  76.1     3.1      M    M
 17000  -12.9   8.8   270   40   20   4.1   2.3   24.0  75.1     2.6      M    M
 16500  -12.2  10.0   275   37   19   7.1   3.9   23.1  73.6     1.9      M    M
 16000  -10.8  12.6   275   35   18   8.8   4.8   22.9  73.3     1.8      M    M
 15500   -9.6  14.7   275   34   17   7.8   4.3   22.7  72.9     1.5      M    M
 15000   -8.4  16.9   275   32   17   7.8   4.3   22.4  72.3     1.3      M    M
 14500   -7.3  18.9   280   31   16   5.5   3.0   22.1  71.7     1.0      M    M
 14000   -6.2  20.8   280   30   15   9.6   5.3   21.6  70.9     0.6      M    M
 13500   -4.8  23.4   280   26   13   9.0   4.9   21.5  70.6     0.5      M    M
 13000   -3.5  25.7   285   23   12   8.9   4.9   21.3  70.4     0.4      M    M
 12500   -2.2  28.0   280   21   11   8.9   4.9   21.2  70.2     0.2      M    M
 12000   -0.8  30.6   275   19   10   8.9   4.9   21.1  69.9     0.1      M    M
 11500    0.5  32.9   270   14    7   8.7   4.8   20.9  69.7    -0.0    491  2.5
 11000    1.3  34.3   265   10    5   2.9   1.6   20.2  68.3    -0.7    454  2.3
 10500    1.7  35.1   255    6    3   4.6   2.5   19.2  66.5    -1.8    426  2.2
 10250    2.1  35.8   235    4    2   7.5   4.1   18.9  66.0    -2.1    406  2.1
 10000    2.7  36.9   225    4    2   8.0   4.4   18.8  65.8    -2.2    381  1.9
  9750    3.3  37.9   205    5    3   7.8   4.3   18.6  65.5    -2.4    356  1.8
  9500    3.9  39.0   190    6    3   7.8   4.3   18.4  65.2    -2.6    332  1.7
  9250    4.4  39.9   180    8    4   7.9   4.3   18.3  64.9    -2.7    307  1.6
  9000    5.0  41.0   175   10    5   7.6   4.2   18.2  64.7    -2.9    282  1.4
  8750    5.5  41.9   170   12    6   6.9   3.3   17.9  64.3    -3.1    260  1.3
  8500    5.9  42.6   165   14    7   5.0   2.7   17.6  63.6    -3.5    241  1.2
  8250    6.3  43.3   160   16    8   5.4   3.0   17.2  63.0    -3.9    223  1.1
  8000    6.6  43.9   155   18    9   4.7   2.6   16.9  62.4    -4.2    205  1.0
  7750    7.0  44.6   150   17    9   7.2   4.0   16.5  61.7    -4.6    186  0.9
  7500    7.7  45.9   145   16    8   9.8   5.4   16.5  61.7    -4.6    158  0.8
  7250    8.4  47.1   140   16    8   9.2   5.0   16.4  61.6    -4.7    129  0.7
  7000    9.1  48.4   135   15    8   9.3   5.1   16.4  61.6    -4.7    101  0.5
  6750    9.8  49.6   135   13    7   9.3   5.1   16.4  61.5    -4.7     72  0.4
  6500   10.5  50.9   130   11    6   9.3   5.1   16.3  61.4    -4.8     44  0.2
  6250   11.2  52.2   125    9    5   9.4   5.2   16.3  61.3    -4.8     15  0.1
  6000   11.9  53.4   120    8    4   8.9   4.9   16.3  61.3    -4.9      M    M
  5750   12.5  54.5   115    6    3   5.3   2.9   16.1  61.0    -5.0      M    M
  5500   12.8  55.0   120    6    3   3.2   1.7   15.6  60.1    -5.5      M    M
  5250   13.0  55.4   120    5    3   4.0   2.2   15.2  59.3    -6.0      M    M
  5000   13.3  55.9   125    4    2   2.8   1.5   14.7  58.5    -6.5      M    M

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

           04/24/2018 at 0900 MDT          |       04/24/2018 at 1200 MDT
                                           |
K index... +19.2  LI... -0.3               | K index... +18.0  LI... +1.4
CAPE... +4.5  CIN... -40.9                 | 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 -59.7 -75.5  295  33 17   1.2   0.6 | -59.7 -75.5  295  31 16   1.0   0.6
 45000 -58.2 -72.8  290  46 24  -1.7  -1.0 | -58.3 -72.9  295  46 24  -0.7  -0.4
 40000 -60.4 -76.7  285  57 29  -1.4  -0.8 | -59.1 -74.4  280  57 29  -0.5  -0.3
 38000 -58.0 -72.4  285  60 31   6.9   3.8 | -56.7 -70.1  280  60 31   5.4   3.0
 36000 -53.3 -63.9  285  63 32   6.9   3.8 | -53.4 -64.1  280  62 32   5.4   3.0
 34000 -49.0 -56.2  285  65 33   7.7   4.2 | -49.6 -57.3  280  63 33   8.0   4.4
 32000 -44.4 -47.9  285  66 34   7.7   4.2 | -44.8 -48.6  280  63 33   7.9   4.4
 30000 -39.7 -39.5  285  67 34   8.1   4.4 | -39.9 -39.8  280  64 33   8.3   4.5
 29000 -37.3 -35.1  285  66 34   8.1   4.4 | -37.5 -35.5  280  65 33   8.3   4.5
 28000 -34.8 -30.6  285  66 34   8.1   4.4 | -35.0 -31.0  280  66 34   8.3   4.5
 27000 -32.6 -26.7  285  65 34   6.3   3.5 | -32.6 -26.7  280  66 34   6.7   3.7
 26000 -30.6 -23.1  280  63 32   6.5   3.6 | -30.5 -22.9  280  65 33   6.8   3.7
 25000 -28.7 -19.7  280  60 31   6.5   3.6 | -28.5 -19.3  280  63 33   6.8   3.7
 24000 -26.7 -16.1  275  57 29   5.8   3.2 | -26.5 -15.7  280  62 32   6.2   3.4
 23000 -25.1 -13.2  275  54 28   5.6   3.1 | -24.7 -12.5  280  59 31   6.0   3.3
 22000 -23.4 -10.1  275  51 26   5.6   3.1 | -22.9  -9.2  275  57 29   6.0   3.3
 21000 -21.8  -7.2  270  47 24   4.7   2.6 | -20.7  -5.3  275  53 27   5.4   3.0
 20000 -20.1  -4.2  270  43 22   4.8   2.6 | -19.1  -2.4  275  50 26   5.4   3.0
 19500 -19.4  -2.9  270  42 22   4.9   2.7 | -18.3  -0.9  275  48 25   5.4   3.0
 19000 -18.6  -1.5  270  40 21   5.6   3.1 | -17.5   0.5  275  46 24   5.6   3.1
 18500 -17.6   0.3  270  39 20   8.3   4.6 | -16.6   2.1  275  44 23   6.3   3.4
 18000 -16.4   2.5  275  38 20   8.3   4.5 | -15.7   3.7  275  42 22   6.3   3.5
 17500 -15.2   4.6  275  38 19   8.4   4.6 | -14.9   5.2  275  41 21   5.6   3.1
 17000 -13.9   7.0  275  37 19   8.5   4.6 | -14.1   6.6  275  39 20   5.8   3.2
 16500 -12.7   9.1  275  37 19   8.7   4.8 | -13.3   8.1  275  38 19   7.0   3.8
 16000 -11.4  11.5  275  37 19   8.9   4.9 | -12.1  10.2  275  36 19   8.2   4.5
 15500 -10.1  13.8  280  36 19   8.9   4.9 | -10.9  12.4  275  35 18   8.4   4.6
 15000  -8.9  16.0  280  34 18   8.6   4.7 |  -9.7  14.5  275  32 17   8.8   4.8
 14500  -7.6  18.3  280  33 17   8.7   4.8 |  -8.4  16.9  270  30 15   8.9   4.9
 14000  -6.4  20.5  280  30 16   7.4   4.1 |  -7.3  18.9  275  27 14   7.2   3.9
 13500  -5.3  22.5  285  28 14   7.7   4.2 |  -6.2  20.8  275  24 12   7.4   4.1
 13000  -4.3  24.3  285  25 13   5.8   3.2 |  -5.1  22.8  275  21 11   6.1   3.4
 12500  -3.4  25.9  290  23 12   5.8   3.2 |  -4.2  24.4  275  18  9   6.2   3.4
 12000  -2.5  27.5  295  19 10   5.3   2.9 |  -3.2  26.2  275  15  8   5.8   3.2
 11500  -1.7  28.9  295  15  8   5.3   2.9 |  -2.4  27.7  270  12  6   5.6   3.1
 11000  -0.8  30.6  295  11  6   6.1   3.3 |  -1.4  29.5  270   9  5   7.4   4.0
 10500   0.0  32.0  285   7  4   6.8   3.7 |  -0.4  31.3  280   7  4   8.5   4.7
 10250   0.4  32.7  275   6  3   3.5   1.9 |   0.1  32.2  285   6  3   3.2   1.7
 10000   0.6  33.1  275   5  2   3.1   1.7 |   0.1  32.2  300   5  3   1.8   1.0
  9750   0.9  33.6  280   4  2   6.2   3.4 |   0.5  32.9  320   5  3   6.3   3.4
  9500   1.2  34.2  290   3  1   5.9   3.2 |   0.8  33.4  340   5  3   5.3   2.9
  9250   1.6  34.9  310   2  1   4.7   2.6 |   1.2  34.2  355   6  3   5.5   3.0
  9000   1.8  35.2  330   2  1   3.7   2.0 |   1.6  34.9  355   6  3   6.6   3.6
  8750   2.1  35.8  355   1  1   4.9   2.7 |   2.2  36.0  360   7  3   8.6   4.7
  8500   2.5  36.5  020   2  1   5.0   2.8 |   2.8  37.0  005   7  4   9.2   5.1
  8250   2.8  37.0  035   2  1   4.7   2.6 |   3.5  38.3  005   8  4   9.5   5.2
  8000   3.2  37.8  045   2  1   4.6   2.5 |   4.2  39.6  005   8  4   9.8   5.4
  7750   3.5  38.3  050   3  1   4.4   2.4 |   5.0  41.0  005   7  4   9.6   5.3
  7500   3.9  39.0  060   3  2   5.3   2.9 |   5.7  42.3  005   7  4  10.2   5.6
  7250   4.3  39.7  050   4  2   6.6   3.6 |   6.5  43.7  005   7  4  10.7   5.9
  7000   4.8  40.6  045   5  2   6.4   3.5 |   7.3  45.1  005   7  4  10.7   5.9
  6750   5.3  41.5  040   5  3   6.8   3.7 |   8.1  46.6  005   7  4  10.3   5.6
  6500   5.9  42.6  035   6  3   9.2   5.0 |   8.8  47.8  005   7  4  10.2   5.6
  6250   6.6  43.9  035   6  3  10.7   5.9 |   9.6  49.3  005   7  4  10.8   5.9
  6000   7.4  45.3  035   5  3   9.8   5.4 |  10.4  50.7  005   7  4  10.1   5.5
  5750   8.3  46.9  035   5  3  14.3   7.9 |  11.4  52.5  005   7  4  18.3  10.1
  5500   9.6  49.3  035   5  3  22.5  12.4 |  13.3  55.9  005   7  4  33.4  18.3
  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

           04/24/2018 at 1500 MDT          |       04/24/2018 at 1800 MDT
                                           |
K index... +7.0  LI... +2.2                | K index... -7.0  LI... +2.6
CAPE... 0.0  CIN... -0.2                   | 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 -59.6 -75.3  300  30 15   1.2   0.7 | -59.8 -75.6  300  29 15   1.0   0.6
 45000 -57.9 -72.2  295  42 22  -0.9  -0.5 | -58.3 -72.9  295  43 22  -0.6  -0.3
 40000 -59.0 -74.2  285  62 32  -0.5  -0.3 | -58.9 -74.0  290  64 33  -0.2  -0.1
 38000 -56.7 -70.1  285  66 34   5.3   2.9 | -56.6 -69.9  290  69 36   5.5   3.0
 36000 -53.6 -64.5  285  70 36   5.3   2.9 | -53.3 -63.9  290  74 38   5.5   3.0
 34000 -49.9 -57.8  285  72 37   7.6   4.2 | -49.5 -57.1  285  77 40   7.7   4.2
 32000 -45.3 -49.5  280  70 36   7.6   4.2 | -44.9 -48.8  285  77 40   7.7   4.2
 30000 -40.5 -40.9  280  69 36   8.4   4.6 | -40.3 -40.5  285  76 39   8.1   4.4
 29000 -38.0 -36.4  280  69 36   8.4   4.6 | -37.8 -36.0  285  75 39   8.1   4.4
 28000 -35.5 -31.9  280  69 35   8.4   4.6 | -35.4 -31.7  285  74 38   8.1   4.4
 27000 -32.5 -26.5  280  68 35   7.3   4.0 | -32.5 -26.5  285  73 37   7.0   3.8
 26000 -30.3 -22.5  280  67 35   7.3   4.0 | -30.4 -22.7  285  71 37   7.0   3.8
 25000 -28.2 -18.8  280  66 34   7.3   4.0 | -28.3 -18.9  285  70 36   7.0   3.9
 24000 -26.1 -15.0  280  64 33   5.6   3.1 | -26.3 -15.3  285  68 35   5.6   3.1
 23000 -24.3 -11.7  280  62 32   5.8   3.2 | -24.6 -12.3  285  65 33   5.7   3.2
 22000 -22.6  -8.7  275  59 31   5.8   3.2 | -22.9  -9.2  285  61 32   5.7   3.1
 21000 -20.9  -5.6  275  56 29   5.8   3.2 | -21.2  -6.2  285  56 29   4.9   2.7
 20000 -19.1  -2.4  275  52 27   5.8   3.2 | -19.8  -3.6  290  49 25   4.9   2.7
 19500 -18.3  -0.9  275  50 26   5.8   3.2 | -19.0  -2.2  290  46 23   4.9   2.7
 19000 -17.4   0.7  275  48 25   5.8   3.2 | -18.3  -0.9  290  42 22   4.7   2.6
 18500 -16.6   2.1  275  46 24   5.4   3.0 | -17.4   0.7  290  39 20   6.9   3.8
 18000 -15.8   3.6  275  43 22   5.5   3.0 | -16.4   2.5  290  37 19   6.7   3.7
 17500 -14.9   5.2  275  41 21   6.0   3.3 | -15.4   4.3  290  34 18   6.3   3.4
 17000 -14.0   6.8  275  38 20   6.2   3.4 | -14.5   5.9  290  32 17   6.0   3.3
 16500 -13.1   8.4  275  36 18   6.3   3.4 | -13.6   7.5  290  31 16   6.1   3.4
 16000 -12.1  10.2  275  34 17   6.5   3.6 | -12.6   9.3  290  29 15   7.0   3.9
 15500 -11.2  11.8  275  32 16   6.5   3.6 | -11.6  11.1  290  28 14   7.0   3.9
 15000 -10.2  13.6  270  30 15   7.3   4.0 | -10.6  12.9  290  27 14   6.7   3.7
 14500  -9.2  15.4  270  29 15   7.4   4.1 |  -9.6  14.7  290  26 13   6.7   3.7
 14000  -8.1  17.4  270  27 14   8.3   4.5 |  -8.6  16.5  290  24 13   7.7   4.2
 13500  -6.9  19.6  270  25 13   8.5   4.7 |  -7.4  18.7  295  23 12   7.9   4.3
 13000  -5.2  22.6  270  22 11   7.2   3.9 |  -5.7  21.7  300  19 10   7.2   4.0
 12500  -4.1  24.6  275  19 10   7.3   4.0 |  -4.7  23.5  305  16  8   7.3   4.0
 12000  -3.1  26.4  280  15  8   6.3   3.5 |  -3.7  25.3  315  14  7   6.8   3.7
 11500  -2.2  28.0  300  11  6   6.4   3.5 |  -2.7  27.1  335  12  6   6.9   3.8
 11000  -1.2  29.8  320   9  5   6.3   3.5 |  -1.6  29.1  350  12  6   8.4   4.6
 10500  -0.3  31.5  345  10  5   5.2   2.9 |  -0.4  31.3  360  13  6   6.8   3.7
 10250  -0.0  32.0  350  10  5   4.5   2.4 |  -0.0  32.0  005  13  7   5.1   2.8
 10000   0.4  32.7  355  10  5   8.5   4.6 |   0.5  32.9  005  13  7   9.4   5.2
  9750   1.1  34.0  355  10  5  10.6   5.8 |   1.3  34.3  005  13  7  12.2   6.7
  9500   1.9  35.4  360  10  5   9.7   5.3 |   2.2  36.0  005  13  7  10.5   5.8
  9250   2.6  36.7  360  10  5   8.9   4.9 |   2.8  37.0  005  13  7   8.1   4.4
  9000   3.2  37.8  360  10  5   9.8   5.4 |   3.4  38.1  005  13  7   9.4   5.2
  8750   4.0  39.2  360  10  5  11.2   6.1 |   4.3  39.7  010  13  6  11.5   6.3
  8500   4.8  40.6  360  11  5  10.2   5.6 |   5.1  41.2  010  13  6  10.4   5.7
  8250   5.6  42.1  360  10  5   9.5   5.2 |   5.8  42.4  010  13  6   9.7   5.3
  8000   6.3  43.3  360  10  5   9.9   5.4 |   6.6  43.9  010  13  6  10.1   5.5
  7750   7.1  44.8  360  10  5  10.4   5.7 |   7.3  45.1  010  12  6  10.5   5.8
  7500   7.8  46.0  360  10  5  10.4   5.7 |   8.1  46.6  010  12  6  10.0   5.5
  7250   8.6  47.5  360  10  5  10.6   5.8 |   8.8  47.8  010  12  6   9.7   5.3
  7000   9.4  48.9  360  10  5  10.0   5.5 |   9.6  49.3  010  12  6   9.9   5.5
  6750  10.1  50.2  360  10  5  10.0   5.5 |  10.3  50.5  010  12  6  10.3   5.7
  6500  10.9  51.6  360  10  5  11.0   6.0 |  11.1  52.0  010  12  6  10.4   5.7
  6250  11.7  53.1  360  10  5  11.2   6.1 |  11.9  53.4  010  12  6  10.6   5.8
  6000  12.6  54.7  360  10  5  10.7   5.9 |  12.7  54.9  010  11  6   9.8   5.4
  5750  13.4  56.1  360   9  5  14.2   7.8 |  13.4  56.1  010  11  6  10.4   5.7
  5500  14.7  58.5  360  10  5  17.8   9.8 |  14.2  57.6  010  11  6  12.0   6.6
  5250  15.9  60.6  360  10  5  15.0   8.2 |  15.1  59.2  010  11  6  10.7   5.9
  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.