Soaring Guidance
Issued by NWS Denver/Boulder, CO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14
000
UXUS97 KBOU 270019
SRGBOU

Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1818 MDT Tuesday, April 26, 2016

This forecast is for Wednesday, April 27, 2016:

If the trigger temperature of 49.1 F/9.5 C is reached...then
   Thermal Soaring Index....................... Poor
   Maximum rate of lift........................ 177 ft/min (0.9 m/s)
   Maximum height of thermals.................. 12851 ft MSL (7544 ft AGL)

Forecast maximum temperature................... 57.0 F/14.3 C
Time of trigger temperature.................... 1030 MDT
Time of overdevelopment........................ 1400 MDT
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 10353 ft MSL (5047 ft AGL)
Thermal soaring outlook for Thursday 04/28..... Fair

Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Decreasing through the day.
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 14430 ft MSL (9123 ft AGL)
Wave soaring outlook for Thursday 04/28........ Fair

Remarks... Weak upper ridge building over the state Wednesday...but airmass
           remaining moist and becoming slightly unstable after 1200 MDT.

Sunrise/Sunset.................... 06:04:28 / 19:49:22 MDT
Total possible sunshine........... 13 hr 44 min 54 sec (824 min 54 sec)
Altitude of sun at 12:57:05 MDT... 64.38 degrees

Upper air data from numerical model forecast valid on 04/27/2016 at 0600 MDT

Freezing level.................. 7390 ft MSL (2083 ft AGL)
Convective condensation level... 11856 ft MSL (6549 ft AGL)
Lifted condensation level....... 12337 ft MSL (7031 ft AGL)
Lifted index.................... +1.4
K index......................... +13.1

Height  Temperature  Wind  Wind Spd  Lapse Rate  ConvectionT  Thermal  Lift Rate
ft MSL  deg C deg F   Dir   kt  m/s  C/km F/kft  deg C deg F   Index    fpm  m/s
--------------------------------------------------------------------------------
 50000  -55.3 -67.5   260   14    7   0.9   0.5      M     M       M      M    M
 45000  -53.9 -65.0   280   16    8   1.0   0.5      M     M       M      M    M
 40000  -54.5 -66.1   280   18    9  -0.5  -0.3      M     M       M      M    M
 38000  -54.7 -66.5   270   14    7   0.4   0.2      M     M       M      M    M
 36000  -54.4 -65.9   165   19   10   0.4   0.2      M     M       M      M    M
 34000  -54.2 -65.6   145   40   21   3.8   2.1      M     M       M      M    M
 32000  -50.2 -58.4   145   18    9   6.7   3.7      M     M       M      M    M
 30000  -46.2 -51.2   350    5    3   7.0   3.8   30.2  86.3    12.2      M    M
 29000  -44.1 -47.4   345   13    7   6.9   3.8   28.9  84.0    11.4      M    M
 28000  -42.0 -43.6   345   20   10   6.9   3.8   27.7  81.9    10.6      M    M
 27000  -39.9 -39.8   345   28   14   6.9   3.8   26.7  80.1    10.0      M    M
 26000  -37.7 -35.9   345   30   16   7.8   4.3   25.8  78.5     9.4      M    M
 25000  -35.3 -31.5   340   30   15   7.9   4.3   25.1  77.1     8.9      M    M
 24000  -33.0 -27.4   340   30   15   7.9   4.3   24.4  76.0     8.5      M    M
 23000  -30.6 -23.1   335   29   15   7.7   4.2   23.7  74.7     8.0      M    M
 22000  -28.3 -18.9   330   29   15   7.7   4.2   22.9  73.2     7.4      M    M
 21000  -26.1 -15.0   330   29   15   7.7   4.2   22.2  72.0     6.9      M    M
 20000  -23.8 -10.8   330   28   15   7.6   4.2   21.4  70.6     6.3      M    M
 19500  -22.6  -8.7   330   28   15   7.6   4.2   21.0  69.9     6.0      M    M
 19000  -21.5  -6.7   325   28   14   7.6   4.2   20.7  69.2     5.7      M    M
 18500  -20.4  -4.7   325   28   14   7.7   4.2   20.3  68.6     5.4      M    M
 18000  -18.7  -1.7   325   28   14   7.1   3.9   19.7  67.5     4.9      M    M
 17500  -17.7   0.1   330   28   14   7.1   3.9   19.3  66.7     4.6      M    M
 17000  -16.6   2.1   330   28   14   6.8   3.7   18.8  65.8     4.2      M    M
 16500  -15.6   3.9   330   28   15   6.8   3.7   18.3  64.9     3.7      M    M
 16000  -14.6   5.7   330   29   15   6.7   3.7   17.8  64.0     3.3      M    M
 15500  -13.7   7.3   330   29   15   6.6   3.6   17.2  63.0     2.8      M    M
 15000  -12.7   9.1   335   30   16   6.5   3.5   16.7  62.1     2.3      M    M
 14500  -11.8  10.8   335   31   16   6.1   3.3   16.1  61.0     1.7      M    M
 14000  -10.9  12.4   335   31   16   6.1   3.3   15.5  59.9     1.2      M    M
 13500  -10.0  14.0   335   31   16   6.3   3.4   14.9  58.9     0.6      M    M
 13000   -9.1  15.6   335   31   16   6.2   3.4   14.4  57.8     0.1      M    M
 12500   -8.1  17.4   335   30   16   7.1   3.9   13.8  56.9    -0.4    541  2.8
 12000   -7.0  19.4   335   29   15   7.3   4.0   13.4  56.1    -0.8    495  2.5
 11500   -6.1  21.0   335   28   15   5.1   2.8   12.8  55.1    -1.4    453  2.3
 11000   -5.4  22.3   330   27   14   5.3   2.9   12.1  53.8    -2.1    416  2.1
 10500   -4.6  23.7   330   25   13   5.0   2.7   11.4  52.5    -2.8    378  1.9
 10250   -4.3  24.3   325   24   12   4.6   2.5   11.0  51.8    -3.2    360  1.8
 10000   -3.9  25.0   325   23   12   6.4   3.5   10.6  51.1    -3.5    342  1.7
  9750   -3.3  26.1   320   21   11   7.4   4.1   10.4  50.8    -3.7    318  1.6
  9500   -2.9  26.8   320   20   11   6.2   3.4   10.2  50.3    -4.0    296  1.5
  9250   -2.4  27.7   315   20   10   6.8   3.7    9.9  49.9    -4.3    274  1.4
  9000   -1.9  28.6   310   19   10   5.8   3.2    9.7  49.4    -4.5    253  1.3
  8750   -1.6  29.1   305   18    9   4.2   2.3    9.3  48.7    -4.9    235  1.2
  8500   -1.3  29.7   305   17    9   3.9   2.2    8.8  47.9    -5.4    219  1.1
  8250   -1.0  30.2   300   16    8   3.7   2.0    8.4  47.1    -5.9    203  1.0
  8000   -0.7  30.7   295   16    8   5.0   2.7    7.9  46.3    -6.3    188  1.0
  7750   -0.4  31.3   290   14    7   4.6   2.5    7.6  45.7    -6.7    169  0.9
  7500   -0.1  31.8   285   12    6   2.9   1.6    7.1  44.8    -7.2    155  0.8
  7250    0.1  32.2   280   11    6   3.4   1.9    6.6  43.9    -7.8    141  0.7
  7000    0.3  32.5   280   10    5   3.9   2.2    6.1  43.1    -8.3    126  0.6
  6750    0.6  33.1   280    9    5   3.1   1.7    5.7  42.2    -8.7    110  0.6
  6500    0.8  33.4   275    8    4   1.7   0.9    5.1  41.2    -9.4     98  0.5
  6250    0.9  33.6   275    8    4   3.2   1.8    4.5  40.2    -9.9     86  0.4
  6000    1.2  34.2   270    7    3   3.7   2.0    4.1  39.4   -10.5     72  0.4
  5750    1.4  34.5   270    5    3   5.5   3.0    3.7  38.6   -11.0     57  0.3
  5500    1.9  35.4   265    4    2   9.2   5.0    3.5  38.3   -11.2     33  0.2

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

           04/27/2016 at 0900 MDT          |       04/27/2016 at 1200 MDT
                                           |
K index... +11.6  LI... +5.1               | K index... +10.3  LI... +3.2
CAPE... 0.0  CIN... M                      | CAPE... 0.0  CIN... M
                                           |
Height Temperature  Wnd WndSpd  Lapse Rate | Temperature  Wnd WndSpd  Lapse Rate
ft MSL deg C deg F  Dir kt m/s  C/km F/kft | deg C deg F  Dir kt m/s  C/km F/kft
--------------------------------------------------------------------------------
 50000 -55.3 -67.5  255  17  9   0.7   0.4 | -56.0 -68.8  255  18  9   0.6   0.3
 45000 -54.2 -65.6  265  18  9   0.8   0.4 | -55.2 -67.4  260  23 12   0.6   0.3
 40000 -54.5 -66.1  290  17  9  -0.3  -0.1 | -55.5 -67.9  295  20 10  -0.3  -0.2
 38000 -54.6 -66.3  295  18  9   0.1   0.0 | -55.2 -67.4  300  23 12   1.8   1.0
 36000 -54.6 -66.3  285  19 10   0.1   0.0 | -54.2 -65.6  295  29 15   1.8   1.0
 34000 -54.5 -66.1  275  21 11   3.5   1.9 | -53.1 -63.6  295  35 18   3.1   1.7
 32000 -50.9 -59.6  295  17  9   6.0   3.3 | -50.3 -58.5  290  28 15   4.8   2.6
 30000 -47.2 -53.0  325  17  9   7.4   4.0 | -47.4 -53.3  285  22 11   6.6   3.6
 29000 -44.9 -48.8  330  19 10   7.6   4.2 | -44.4 -47.9  285  18  9   8.0   4.4
 28000 -42.6 -44.7  335  21 11   7.6   4.2 | -42.0 -43.6  290  15  7   8.0   4.4
 27000 -40.3 -40.5  340  23 12   7.6   4.2 | -39.6 -39.3  290  11  6   8.0   4.4
 26000 -37.9 -36.2  340  24 12   8.4   4.6 | -37.0 -34.6  285  11  6   8.5   4.7
 25000 -35.3 -31.5  340  24 13   8.5   4.6 | -34.5 -30.1  280  12  6   8.5   4.7
 24000 -32.8 -27.0  335  25 13   8.5   4.6 | -31.9 -25.4  275  13  7   8.5   4.7
 23000 -30.2 -22.4  335  25 13   8.7   4.8 | -29.4 -20.9  275  14  7   8.5   4.7
 22000 -27.6 -17.7  335  25 13   8.7   4.8 | -26.9 -16.4  280  14  7   8.5   4.7
 21000 -25.0 -13.0  330  25 13   8.8   4.8 | -24.3 -11.7  285  15  8   8.4   4.6
 20000 -22.7  -8.9  330  25 13   7.5   4.1 | -22.0  -7.6  290  16  8   7.7   4.2
 19500 -21.5  -6.7  330  25 13   7.6   4.1 | -20.9  -5.6  290  16  8   7.7   4.2
 19000 -20.4  -4.7  325  25 13   7.6   4.2 | -19.7  -3.5  295  16  8   7.7   4.2
 18500 -19.3  -2.7  325  25 13   7.7   4.2 | -18.6  -1.5  295  17  9   7.8   4.3
 18000 -17.7   0.1  320  24 13   6.6   3.6 | -17.6   0.3  300  18  9   5.5   3.0
 17500 -16.8   1.8  320  24 12   6.6   3.6 | -16.7   1.9  300  19 10   5.7   3.1
 17000 -15.8   3.6  320  24 12   6.5   3.5 | -15.9   3.4  300  20 10   5.9   3.2
 16500 -14.8   5.4  315  24 12   6.5   3.6 | -15.0   5.0  305  21 11   6.0   3.3
 16000 -13.9   7.0  315  24 12   6.1   3.3 | -14.1   6.6  305  22 11   6.1   3.3
 15500 -13.0   8.6  315  24 13   5.9   3.2 | -13.2   8.2  310  22 12   6.2   3.4
 15000 -12.2  10.0  315  25 13   5.7   3.1 | -11.9  10.6  310  24 12   6.4   3.5
 14500 -11.4  11.5  315  25 13   5.4   3.0 | -10.9  12.4  315  24 12   6.7   3.7
 14000 -10.6  12.9  320  25 13   5.4   3.0 | -10.0  14.0  315  25 13   6.7   3.7
 13500  -9.8  14.4  320  25 13   5.4   3.0 |  -9.0  15.8  315  26 13   6.9   3.8
 13000  -9.0  15.8  325  26 13   5.4   3.0 |  -7.9  17.8  320  27 14   7.0   3.8
 12500  -8.2  17.2  325  26 13   5.0   2.8 |  -6.9  19.6  320  28 14   7.7   4.2
 12000  -7.5  18.5  330  26 14   4.9   2.7 |  -5.7  21.7  320  29 15   7.6   4.1
 11500  -6.6  20.1  330  27 14   7.6   4.2 |  -4.8  23.4  320  28 14   5.4   3.0
 11000  -5.5  22.1  330  27 14   7.4   4.1 |  -4.0  24.8  315  26 13   5.6   3.1
 10500  -4.5  23.9  330  27 14   5.3   2.9 |  -3.2  26.2  315  24 12   5.8   3.2
 10250  -4.1  24.6  335  27 14   4.9   2.7 |  -2.8  27.0  315  23 12   6.2   3.4
 10000  -3.7  25.3  335  27 14   7.2   4.0 |  -2.2  28.0  315  22 11   8.6   4.7
  9750  -3.1  26.4  335  26 13   8.0   4.4 |  -1.6  29.1  315  20 10   8.0   4.4
  9500  -2.6  27.3  335  25 13   6.3   3.5 |  -1.1  30.0  320  19 10   6.2   3.4
  9250  -2.1  28.2  335  24 12   6.3   3.5 |  -0.6  30.9  320  17  9   6.5   3.6
  9000  -1.6  29.1  335  23 12   8.0   4.4 |  -0.1  31.8  325  16  8   7.0   3.8
  8750  -1.0  30.2  335  22 11   8.6   4.7 |   0.4  32.7  325  15  8   6.7   3.7
  8500  -0.4  31.3  335  21 11   7.3   4.0 |   0.8  33.4  330  13  7   5.9   3.2
  8250   0.1  32.2  335  20 10   7.6   4.2 |   1.2  34.2  340  11  6   5.7   3.1
  8000   0.7  33.3  330  19 10   7.6   4.2 |   1.7  35.1  350   9  5   8.5   4.7
  7750   1.2  34.2  330  18  9   6.3   3.5 |   2.4  36.3  355   8  4  10.0   5.5
  7500   1.7  35.1  330  18  9   5.5   3.0 |   3.0  37.4  360   8  4   8.4   4.6
  7250   2.1  35.8  330  18  9   5.0   2.8 |   3.7  38.7  360   8  4   9.4   5.1
  7000   2.4  36.3  330  17  9   3.6   2.0 |   4.4  39.9  360   8  4  10.6   5.8
  6750   2.5  36.5  330  15  8   1.4   0.8 |   5.2  41.4  005   8  4  10.1   5.5
  6500   2.5  36.5  335  12  6  -0.8  -0.5 |   5.9  42.6  005   8  4   8.8   4.8
  6250   2.5  36.5  335   8  4   4.0   2.2 |   6.6  43.9  005   7  4  10.8   5.9
  6000   3.0  37.4  335   6  3   7.8   4.3 |   7.5  45.5  005   7  4  13.1   7.2
  5750   3.4  38.1  330   4  2   6.9   3.8 |   8.4  47.1  005   7  4  10.2   5.6
  5500   4.1  39.4  325   3  1  13.8   7.6 |   9.2  48.6  005   7  3  13.9   7.6

           04/27/2016 at 1500 MDT          |       04/27/2016 at 1800 MDT
                                           |
K index... +17.6  LI... +0.8               | K index... +15.6  LI... -0.1
CAPE... +20.0  CIN... -30.8                | CAPE... +20.2  CIN... -12.1
                                           |
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 -56.6 -69.9  245  17  9   0.5   0.3 | -56.8 -70.2  245  19 10   0.6   0.3
 45000 -55.8 -68.4  260  21 11   0.5   0.3 | -55.9 -68.6  260  24 12   0.7   0.4
 40000 -56.0 -68.8  280  21 11  -0.2  -0.1 | -57.7 -71.9  280  31 16  -1.3  -0.7
 38000 -55.7 -68.3  290  24 13   1.6   0.9 | -57.3 -71.1  285  35 18   3.5   1.9
 36000 -54.7 -66.5  295  34 17   1.6   0.9 | -55.2 -67.4  285  39 20   3.5   1.9
 34000 -53.7 -64.7  295  43 22   5.2   2.9 | -52.9 -63.2  285  43 22   6.3   3.4
 32000 -49.2 -56.6  300  45 23   7.5   4.1 | -48.8 -55.8  290  39 20   6.9   3.8
 30000 -44.1 -47.4  300  47 24   8.1   4.4 | -44.6 -48.3  290  36 19   8.3   4.6
 29000 -41.7 -43.1  300  43 22   8.1   4.4 | -41.5 -42.7  290  36 19   8.4   4.6
 28000 -39.3 -38.7  300  40 21   8.1   4.4 | -39.0 -38.2  290  36 19   8.4   4.6
 27000 -36.8 -34.2  300  37 19   8.0   4.4 | -36.5 -33.7  295  36 19   8.4   4.6
 26000 -34.8 -30.6  295  33 17   6.6   3.6 | -33.9 -29.0  295  35 18   8.4   4.6
 25000 -32.8 -27.0  290  28 14   6.6   3.6 | -31.4 -24.5  295  34 18   8.4   4.6
 24000 -30.9 -23.6  285  24 12   6.5   3.6 | -28.9 -20.0  295  33 17   8.7   4.8
 23000 -28.8 -19.8  280  22 11   6.9   3.8 | -26.9 -16.4  295  32 17   6.0   3.3
 22000 -26.8 -16.2  275  22 11   6.9   3.8 | -25.1 -13.2  290  31 16   6.0   3.3
 21000 -24.7 -12.5  270  22 11   7.0   3.9 | -23.3  -9.9  285  31 16   6.1   3.3
 20000 -22.4  -8.3  270  23 12   7.9   4.3 | -21.5  -6.7  285  31 16   6.4   3.5
 19500 -21.2  -6.2  270  23 12   7.9   4.3 | -20.5  -4.9  285  31 16   6.4   3.5
 19000 -20.1  -4.2  275  24 12   7.9   4.3 | -19.6  -3.3  280  31 16   6.4   3.5
 18500 -18.9  -2.0  275  24 12   8.0   4.4 | -18.7  -1.7  280  31 16   6.5   3.6
 18000 -17.8  -0.0  275  25 13   6.1   3.4 | -17.7   0.1  280  32 16   6.5   3.6
 17500 -16.9   1.6  280  25 13   6.4   3.5 | -16.8   1.8  280  32 17   6.5   3.6
 17000 -16.0   3.2  285  25 13   5.9   3.3 | -15.8   3.6  285  32 17   6.7   3.7
 16500 -15.2   4.6  290  26 14   5.7   3.1 | -14.8   5.4  285  33 17   6.8   3.7
 16000 -14.4   6.1  290  27 14   5.8   3.2 | -13.8   7.2  285  33 17   7.1   3.9
 15500 -13.0   8.6  295  28 15   6.4   3.5 | -12.0  10.4  285  32 17   8.1   4.4
 15000 -12.1  10.2  300  29 15   7.2   4.0 | -10.9  12.4  290  31 16   7.9   4.3
 14500 -10.9  12.4  300  28 15   8.1   4.4 |  -9.7  14.5  290  29 15   7.8   4.3
 14000  -9.7  14.5  300  28 14   8.2   4.5 |  -8.6  16.5  290  28 14   7.7   4.2
 13500  -8.5  16.7  300  26 13   8.2   4.5 |  -7.5  18.5  290  25 13   7.5   4.1
 13000  -7.3  18.9  300  24 13   8.2   4.5 |  -6.5  20.3  295  22 12   7.4   4.0
 12500  -6.2  20.8  300  22 12   7.9   4.3 |  -5.5  22.1  295  19 10   5.9   3.2
 12000  -5.0  23.0  300  21 11   7.9   4.3 |  -4.7  23.5  300  15  7   6.0   3.3
 11500  -3.9  25.0  305  18  9   7.0   3.9 |  -3.8  25.2  305  10  5   5.9   3.3
 11000  -2.9  26.8  315  15  8   6.9   3.8 |  -3.0  26.6  320   6  3   6.0   3.3
 10500  -2.2  28.0  330  12  6   3.9   2.1 |  -2.1  28.2  350   4  2   6.3   3.4
 10250  -1.9  28.6  340  10  5   4.3   2.4 |  -1.6  29.1  015   4  2   6.6   3.6
 10000  -1.5  29.3  360   9  5   5.7   3.1 |  -1.1  30.0  035   5  3   8.3   4.6
  9750  -1.0  30.2  010   8  4   7.9   4.3 |  -0.4  31.3  040   6  3   9.5   5.2
  9500  -0.4  31.3  015   8  4   8.5   4.7 |   0.3  32.5  040   6  3   9.4   5.1
  9250   0.2  32.4  020   8  4   8.4   4.6 |   0.9  33.6  040   6  3   9.8   5.4
  9000   0.8  33.4  020   8  4   8.3   4.6 |   1.6  34.9  040   6  3   8.3   4.6
  8750   1.4  34.5  025   8  4   9.3   5.1 |   2.2  36.0  040   6  3   8.7   4.8
  8500   2.1  35.8  025   8  4  10.2   5.6 |   3.0  37.4  040   6  3  10.5   5.8
  8250   2.9  37.2  025   8  4   9.7   5.3 |   3.7  38.7  040   6  3   9.9   5.5
  8000   3.6  38.5  025   8  4  11.1   6.1 |   4.5  40.1  040   6  3  10.8   5.9
  7750   4.5  40.1  025   8  4  10.6   5.8 |   5.3  41.5  040   6  3  10.0   5.5
  7500   5.2  41.4  025   8  4   8.9   4.9 |   5.9  42.6  040   6  3   8.6   4.7
  7250   5.9  42.6  025   8  4   9.7   5.3 |   6.6  43.9  040   6  3   9.6   5.3
  7000   6.6  43.9  025   8  4  10.6   5.8 |   7.4  45.3  040   6  3  11.5   6.3
  6750   7.4  45.3  025   8  4  10.4   5.7 |   8.2  46.8  040   6  3  10.4   5.7
  6500   8.2  46.8  025   8  4   9.5   5.2 |   8.9  48.0  040   6  3   8.5   4.7
  6250   8.9  48.0  025   8  4  10.6   5.8 |   9.6  49.3  040   6  3   9.9   5.4
  6000   9.7  49.5  025   8  4  11.9   6.5 |  10.4  50.7  040   6  3  11.0   6.0
  5750  10.6  51.1  020   8  4  10.5   5.8 |  11.2  52.2  035   6  3  10.0   5.5
  5500  11.5  52.7  020   7  4  15.5   8.5 |  11.9  53.4  035   6  3  11.5   6.3
________________________________________________________________________________

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.