686 UXUS97 KBOU 091309 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0708 MDT Wednesday, September 9, 2015 This forecast is for Wednesday, September 9, 2015: If the trigger temperature of 78.5 F/25.9 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 905 ft/min (4.6 m/s) Maximum height of thermals.................. 15389 ft MSL (10104 ft AGL) Forecast maximum temperature................... 85.0 F/29.9 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................. 10441 ft MSL (5155 ft AGL) Thermal soaring outlook for Thursday 09/10..... Excellent Wave Soaring Index............................. Poor Wave Soaring Index trend (to 1800 MDT)......... Same Height of stable layer (12-18K ft MSL)......... 15144 ft MSL (9859 ft AGL) Weak PVA/NVA (through 1800 MDT)................ Weak NVA Potential height of wave....................... 16130 ft MSL (10845 ft AGL) Wave soaring outlook for Thursday 09/10........ Poor Remarks... Sunrise/Sunset.................... 06:34:44 / 19:19:43 MDT Total possible sunshine........... 12 hr 44 min 59 sec (764 min 59 sec) Altitude of sun at 12:56:45 MDT... 55.45 degrees Upper air data from rawinsonde observation taken on 09/09/2015 at 0600 MDT Freezing level.................. 14606 ft MSL (9321 ft AGL) Convective condensation level... 20390 ft MSL (15105 ft AGL) Lifted condensation level....... 18935 ft MSL (13649 ft AGL) Lifted index.................... +3.3 K index......................... +0.4 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 -62.2 -80.0 300 48 25 2.5 1.4 90.7 195.2 35.5 M M 45000 -62.7 -80.9 290 61 31 -0.1 -0.0 65.5 149.9 22.4 M M 40000 -58.5 -73.3 285 61 31 7.7 4.2 49.1 120.3 13.1 M M 38000 -53.9 -65.0 285 55 28 7.6 4.2 47.1 116.8 12.1 M M 36000 -48.8 -55.8 280 49 25 9.1 5.0 46.2 115.2 11.8 M M 34000 -43.7 -46.7 275 42 22 8.1 4.5 45.2 113.3 11.3 M M 32000 -38.3 -36.9 260 39 20 8.7 4.8 43.6 110.4 10.5 M M 30000 -33.1 -27.6 265 37 19 8.6 4.7 42.7 108.9 10.1 M M 29000 -30.5 -22.9 265 35 18 8.6 4.7 42.2 107.9 9.8 M M 28000 -28.0 -18.4 265 34 17 8.6 4.7 41.7 107.1 9.5 M M 27000 -25.4 -13.7 265 32 16 8.6 4.7 41.4 106.5 9.4 M M 26000 -22.8 -9.0 270 31 16 8.7 4.8 40.8 105.5 9.1 M M 25000 -20.7 -5.3 275 30 15 6.0 3.3 39.8 103.6 8.3 M M 24000 -18.6 -1.5 285 29 15 7.7 4.2 38.8 101.8 7.6 M M 23000 -17.2 1.0 285 30 16 3.7 2.0 37.0 98.6 6.2 M M 22000 -15.5 4.1 290 31 16 7.1 3.9 35.5 96.0 5.0 M M 21000 -13.3 8.1 290 26 13 7.2 4.0 34.6 94.2 4.2 M M 20000 -11.2 11.8 295 20 11 8.0 4.4 33.7 92.7 3.5 M M 19500 -10.5 13.1 300 18 9 1.3 0.7 32.8 91.0 2.7 M M 19000 -9.7 14.5 310 15 8 8.1 4.5 32.0 89.7 2.1 M M 18500 -8.5 16.7 305 13 7 8.0 4.4 31.7 89.1 1.8 M M 18000 -7.3 18.9 295 10 5 7.9 4.4 31.5 88.6 1.6 M M 17500 -6.1 21.0 295 11 6 7.9 4.4 31.1 88.1 1.3 M M 17000 -4.9 23.2 300 12 6 7.9 4.4 30.8 87.5 1.1 M M 16500 -3.8 25.2 285 13 7 7.9 4.4 30.5 87.0 0.8 M M 16000 -2.0 28.4 270 15 8 7.9 4.3 30.1 86.1 0.4 M M 15500 -0.9 30.4 265 13 7 4.9 2.7 29.7 85.4 0.0 M M 15000 -0.4 31.3 260 10 5 3.4 1.9 28.5 83.4 -1.0 877 4.5 14500 0.5 32.9 270 6 3 9.2 5.0 28.0 82.5 -1.5 833 4.2 14000 1.8 35.2 305 3 2 8.7 4.8 27.9 82.2 -1.7 780 4.0 13500 3.1 37.6 310 3 1 8.7 4.8 27.7 81.9 -1.9 726 3.7 13000 4.4 39.9 315 2 1 8.7 4.8 27.5 81.6 -2.1 673 3.4 12500 5.7 42.3 320 2 1 8.7 4.8 27.4 81.3 -2.2 619 3.1 12000 7.0 44.6 320 2 1 8.7 4.8 27.3 81.1 -2.4 566 2.9 11500 8.3 46.9 270 3 1 8.7 4.8 27.1 80.7 -2.6 512 2.6 11000 9.6 49.3 250 4 2 8.7 4.8 26.9 80.4 -2.8 459 2.3 10500 10.9 51.6 240 6 3 8.7 4.8 26.7 80.1 -3.0 405 2.1 10250 11.5 52.7 240 6 3 8.6 4.7 26.6 79.9 -3.1 379 1.9 10000 12.1 53.8 240 5 3 8.6 4.7 26.5 79.8 -3.2 352 1.8 9750 12.8 55.0 240 5 3 8.6 4.7 26.5 79.6 -3.3 326 1.7 9500 13.4 56.1 235 5 2 8.7 4.7 26.4 79.5 -3.4 299 1.5 9250 14.0 57.2 235 4 2 8.7 4.7 26.3 79.4 -3.5 272 1.4 9000 14.7 58.5 235 4 2 8.7 4.8 26.2 79.2 -3.6 246 1.2 8750 15.3 59.5 220 4 2 8.7 4.8 26.2 79.1 -3.7 219 1.1 8500 16.0 60.8 205 5 3 8.7 4.8 26.1 78.9 -3.8 193 1.0 8250 16.6 61.9 195 6 3 8.7 4.8 26.0 78.8 -3.9 166 0.8 8000 17.2 63.0 190 7 4 8.6 4.7 25.9 78.6 -4.0 140 0.7 7750 17.9 64.2 195 7 3 8.8 4.8 25.8 78.5 -4.1 113 0.6 7500 18.5 65.3 200 6 3 8.2 4.5 25.7 78.3 -4.2 87 0.4 7250 19.2 66.6 205 6 3 10.4 5.7 25.6 78.2 -4.3 60 0.3 7000 19.8 67.6 210 6 3 2.3 1.2 25.6 78.0 -4.4 34 0.2 6750 19.5 67.1 215 8 4 -5.9 -3.3 24.5 76.1 -5.5 36 0.2 6500 19.1 66.4 215 11 6 -4.0 -2.2 23.4 74.2 -6.6 40 0.2 6250 18.7 65.7 220 13 7 -4.0 -2.2 22.4 72.2 -7.7 43 0.2 6000 18.4 65.1 220 16 8 -5.6 -3.1 21.3 70.3 -8.8 46 0.2 5750 17.7 63.9 225 12 6 -9.5 -5.2 20.0 68.0 -10.2 58 0.3 5500 16.5 61.7 230 9 4 -20.7 -11.4 18.2 64.8 -12.1 87 0.4 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 09/09/2015 at 0900 MDT | 09/09/2015 at 1200 MDT | K index... +2.7 LI... +2.8 | K index... +5.4 LI... +2.2 CAPE... 0.0 CIN... -0.6 | CAPE... 0.0 CIN... -0.3 | 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 -64.1 -83.4 300 42 22 0.4 0.2 | -64.4 -83.9 300 44 22 1.1 0.6 45000 -62.0 -79.6 300 52 27 4.3 2.4 | -61.4 -78.5 305 56 29 4.2 2.3 40000 -55.4 -67.7 295 52 27 6.2 3.4 | -54.8 -66.6 295 58 30 7.0 3.8 38000 -51.8 -61.2 290 47 24 6.0 3.3 | -50.8 -59.4 295 51 26 6.7 3.7 36000 -48.2 -54.8 285 43 22 6.0 3.3 | -46.7 -52.1 290 45 23 6.7 3.7 34000 -43.7 -46.7 280 42 21 8.0 4.4 | -42.7 -44.9 290 41 21 6.8 3.7 32000 -38.4 -37.1 275 41 21 7.9 4.4 | -38.1 -36.6 285 39 20 6.7 3.7 30000 -33.5 -28.3 275 37 19 8.0 4.4 | -33.6 -28.5 285 37 19 7.7 4.2 29000 -31.1 -24.0 275 35 18 8.0 4.4 | -31.3 -24.3 285 36 18 7.7 4.2 28000 -28.7 -19.7 280 33 17 7.7 4.2 | -28.9 -20.0 285 35 18 7.5 4.1 27000 -26.5 -15.7 280 31 16 7.3 4.0 | -26.8 -16.2 285 33 17 7.3 4.0 26000 -24.3 -11.7 280 28 14 7.3 4.0 | -24.6 -12.3 285 30 16 7.3 4.0 25000 -22.1 -7.8 285 26 13 7.4 4.0 | -22.4 -8.3 285 28 14 7.4 4.1 24000 -20.0 -4.0 285 24 13 6.9 3.8 | -20.3 -4.5 285 26 14 6.7 3.7 23000 -18.0 -0.4 290 24 12 6.9 3.8 | -18.3 -0.9 285 25 13 6.7 3.7 22000 -15.9 3.4 290 23 12 7.0 3.8 | -16.3 2.7 285 23 12 6.8 3.7 21000 -13.8 7.2 295 22 12 7.3 4.0 | -14.1 6.6 285 22 11 7.7 4.3 20000 -11.6 11.1 295 22 11 7.3 4.0 | -11.7 10.9 285 21 11 7.7 4.2 19500 -10.5 13.1 295 21 11 7.3 4.0 | -10.6 12.9 285 20 10 7.8 4.3 19000 -9.4 15.1 295 21 11 7.1 3.9 | -9.4 15.1 285 19 10 7.4 4.1 18500 -8.4 16.9 300 20 10 7.1 3.9 | -8.3 17.1 285 19 10 7.4 4.1 18000 -7.3 18.9 300 20 10 7.2 4.0 | -7.2 19.0 285 18 9 7.4 4.1 17500 -6.2 20.8 300 19 10 7.5 4.1 | -6.1 21.0 285 17 9 7.4 4.1 17000 -5.1 22.8 305 18 10 7.5 4.1 | -5.0 23.0 290 17 9 7.4 4.1 16500 -3.4 25.9 305 18 9 7.9 4.3 | -3.4 25.9 295 17 9 7.6 4.2 16000 -2.2 28.0 305 17 9 7.9 4.3 | -2.2 28.0 300 17 9 7.7 4.2 15500 -1.0 30.2 305 17 9 8.0 4.4 | -1.1 30.0 300 18 9 8.3 4.5 15000 0.2 32.4 305 16 8 8.0 4.4 | 0.1 32.2 300 18 10 8.3 4.5 14500 1.4 34.5 300 16 8 8.2 4.5 | 1.3 34.3 300 19 10 8.5 4.7 14000 2.6 36.7 300 15 8 8.3 4.5 | 2.5 36.5 300 19 10 8.6 4.7 13500 3.8 38.8 300 14 7 8.2 4.5 | 3.7 38.7 305 19 10 8.8 4.8 13000 5.0 41.0 300 13 7 8.2 4.5 | 5.0 41.0 305 18 9 8.9 4.9 12500 6.2 43.2 295 12 6 8.3 4.5 | 6.3 43.3 305 17 9 8.8 4.8 12000 7.5 45.5 295 11 5 8.3 4.6 | 7.6 45.7 305 15 8 8.6 4.7 11500 8.7 47.7 290 9 5 8.4 4.6 | 8.9 48.0 305 14 7 8.4 4.6 11000 9.9 49.8 285 8 4 8.1 4.4 | 10.2 50.4 305 12 6 7.9 4.3 10500 11.1 52.0 280 6 3 4.4 2.4 | 11.4 52.5 305 9 5 3.8 2.1 10250 11.3 52.3 275 6 3 4.8 2.6 | 11.6 52.9 305 9 5 5.2 2.8 10000 12.0 53.6 275 5 3 10.9 6.0 | 12.4 54.3 305 8 4 11.6 6.4 9750 12.7 54.9 270 4 2 10.6 5.8 | 13.1 55.6 300 7 3 10.3 5.7 9500 13.5 56.3 270 4 2 8.9 4.9 | 13.9 57.0 300 5 3 9.1 5.0 9250 14.0 57.2 265 3 2 6.5 3.6 | 14.5 58.1 295 5 2 7.1 3.9 9000 14.5 58.1 260 3 2 8.7 4.8 | 15.1 59.2 290 4 2 8.6 4.7 8750 15.3 59.5 255 3 2 10.3 5.6 | 15.8 60.4 280 3 2 9.6 5.3 8500 15.9 60.6 255 3 2 8.7 4.8 | 16.5 61.7 270 2 1 8.5 4.7 8250 16.5 61.7 250 3 2 7.7 4.2 | 17.0 62.6 270 2 1 7.5 4.1 8000 17.1 62.8 250 3 2 7.9 4.3 | 17.6 63.7 265 1 1 8.3 4.5 7750 17.6 63.7 245 3 2 7.5 4.1 | 18.2 64.8 265 1 1 9.1 5.0 7500 18.2 64.8 245 4 2 7.1 3.9 | 18.8 65.8 275 1 0 9.7 5.3 7250 18.7 65.7 245 4 2 6.6 3.6 | 19.5 67.1 285 1 0 10.1 5.5 7000 19.2 66.6 245 5 2 7.9 4.3 | 20.3 68.5 300 1 0 10.0 5.5 6750 19.7 67.5 245 5 3 6.2 3.4 | 21.0 69.8 305 1 0 10.4 5.7 6500 20.0 68.0 245 6 3 1.3 0.7 | 21.8 71.2 310 1 0 10.7 5.9 6250 20.0 68.0 245 6 3 1.0 0.5 | 22.6 72.7 315 1 0 11.2 6.1 6000 20.1 68.2 245 6 3 -1.1 -0.6 | 23.4 74.1 320 1 1 9.8 5.4 5750 19.8 67.6 235 6 3 -2.4 -1.3 | 24.2 75.6 320 1 1 14.6 8.0 5500 19.8 67.6 225 5 3 2.7 1.5 | 25.7 78.3 320 1 1 26.4 14.5 09/09/2015 at 1500 MDT | 09/09/2015 at 1800 MDT | K index... +19.9 LI... +1.7 | K index... +18.6 LI... +0.8 CAPE... 0.0 CIN... M | CAPE... 0.0 CIN... -0.8 | 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 -65.2 -85.4 295 49 25 1.4 0.8 | -64.7 -84.5 290 53 27 1.3 0.7 45000 -61.5 -78.7 300 62 32 5.5 3.0 | -61.2 -78.2 290 66 34 5.3 2.9 40000 -53.1 -63.6 300 66 34 5.9 3.3 | -53.2 -63.8 290 69 35 6.8 3.7 38000 -49.6 -57.3 295 59 30 5.9 3.2 | -49.1 -56.4 290 64 33 6.7 3.7 36000 -46.0 -50.8 295 51 26 5.9 3.3 | -45.1 -49.2 295 59 30 6.7 3.6 34000 -42.2 -44.0 290 45 23 6.6 3.6 | -41.2 -42.2 295 50 26 5.6 3.1 32000 -37.7 -35.9 290 39 20 6.5 3.6 | -37.8 -36.0 295 43 22 5.6 3.1 30000 -33.5 -28.3 290 36 18 7.0 3.9 | -33.8 -28.8 295 38 20 7.0 3.8 29000 -31.4 -24.5 290 34 18 7.1 3.9 | -31.7 -25.1 295 37 19 7.0 3.8 28000 -29.3 -20.7 295 33 17 7.3 4.0 | -29.6 -21.3 295 35 18 7.1 3.9 27000 -27.1 -16.8 295 32 16 7.6 4.2 | -27.4 -17.3 295 35 18 7.3 4.0 26000 -24.8 -12.6 295 31 16 7.6 4.2 | -25.3 -13.5 295 34 17 7.3 4.0 25000 -22.5 -8.5 295 30 16 7.6 4.2 | -23.1 -9.6 295 33 17 7.3 4.0 24000 -20.4 -4.7 290 29 15 7.1 3.9 | -21.0 -5.8 295 32 16 7.2 3.9 23000 -18.3 -0.9 290 27 14 7.1 3.9 | -18.8 -1.8 290 30 15 7.2 3.9 22000 -16.2 2.8 290 25 13 7.1 3.9 | -16.7 1.9 290 28 15 7.2 4.0 21000 -13.9 7.0 285 24 13 7.7 4.2 | -14.4 6.1 285 28 14 7.9 4.3 20000 -11.6 11.1 285 24 12 7.7 4.2 | -12.1 10.2 280 27 14 7.9 4.4 19500 -10.4 13.3 285 23 12 7.7 4.2 | -10.9 12.4 275 27 14 7.9 4.4 19000 -9.3 15.3 285 23 12 7.7 4.2 | -9.7 14.5 275 27 14 8.6 4.7 18500 -8.2 17.2 280 23 12 7.7 4.2 | -8.4 16.9 275 26 13 8.7 4.8 18000 -7.1 19.2 280 23 12 7.8 4.3 | -7.1 19.2 280 25 13 8.6 4.7 17500 -5.9 21.4 280 23 12 8.1 4.5 | -5.3 22.5 280 23 12 8.3 4.5 17000 -4.2 24.4 280 23 12 8.1 4.4 | -4.1 24.6 280 23 12 8.3 4.6 16500 -3.0 26.6 280 23 12 7.9 4.3 | -2.9 26.8 285 22 11 8.4 4.6 16000 -1.9 28.6 280 22 11 7.9 4.4 | -1.6 29.1 285 21 11 8.3 4.6 15500 -0.8 30.6 280 21 11 8.6 4.7 | -0.3 31.5 285 20 10 9.4 5.2 15000 0.5 32.9 280 20 10 8.6 4.7 | 1.0 33.8 285 19 10 9.3 5.1 14500 1.8 35.2 275 18 9 9.0 4.9 | 2.4 36.3 290 18 9 9.0 4.9 14000 3.1 37.6 280 17 9 9.1 5.0 | 3.7 38.7 290 16 8 8.9 4.9 13500 4.5 40.1 280 15 8 8.8 4.8 | 5.1 41.2 290 14 7 8.9 4.9 13000 5.8 42.4 280 14 7 8.6 4.7 | 6.4 43.5 290 12 6 8.9 4.9 12500 7.1 44.8 280 12 6 8.6 4.7 | 7.7 45.9 295 11 5 8.9 4.9 12000 8.4 47.1 285 11 6 8.6 4.7 | 9.1 48.4 295 9 5 9.0 4.9 11500 9.7 49.5 285 10 5 8.7 4.8 | 10.4 50.7 300 7 4 8.9 4.9 11000 11.0 51.8 290 8 4 8.6 4.7 | 11.7 53.1 300 6 3 8.3 4.6 10500 12.3 54.1 295 5 3 3.8 2.1 | 13.0 55.4 305 5 3 5.0 2.8 10250 12.4 54.3 300 5 3 4.9 2.7 | 13.2 55.8 305 5 2 6.1 3.4 10000 13.2 55.8 300 4 2 12.0 6.6 | 14.0 57.2 310 4 2 11.2 6.2 9750 14.0 57.2 305 3 2 10.6 5.8 | 14.8 58.6 315 4 2 10.3 5.7 9500 14.8 58.6 310 2 1 9.3 5.1 | 15.5 59.9 320 3 2 8.9 4.9 9250 15.4 59.7 315 2 1 7.5 4.1 | 16.1 61.0 330 3 2 6.4 3.5 9000 16.0 60.8 320 2 1 9.8 5.4 | 16.6 61.9 340 3 2 8.4 4.6 8750 16.8 62.2 320 2 1 11.0 6.0 | 17.3 63.1 345 4 2 9.6 5.3 8500 17.6 63.7 325 2 1 10.4 5.7 | 17.9 64.2 350 4 2 9.4 5.2 8250 18.4 65.1 325 2 1 10.1 5.6 | 18.7 65.7 355 4 2 9.7 5.3 8000 19.2 66.6 320 2 1 10.1 5.5 | 19.4 66.9 355 4 2 9.6 5.2 7750 19.9 67.8 325 2 1 10.0 5.5 | 20.1 68.2 355 4 2 9.3 5.1 7500 20.6 69.1 325 2 1 9.9 5.4 | 20.8 69.4 350 4 2 9.9 5.4 7250 21.4 70.5 325 2 1 9.7 5.3 | 21.6 70.9 350 5 2 10.5 5.8 7000 22.1 71.8 325 2 1 9.8 5.4 | 22.4 72.3 350 5 2 10.2 5.6 6750 22.9 73.2 325 2 1 10.2 5.6 | 23.1 73.6 345 5 2 9.7 5.3 6500 23.7 74.7 320 2 1 10.6 5.8 | 23.8 74.8 345 5 2 10.0 5.5 6250 24.5 76.1 320 2 1 11.3 6.2 | 24.6 76.3 345 5 2 10.5 5.7 6000 25.3 77.5 320 2 1 9.2 5.0 | 25.4 77.7 345 5 2 9.9 5.4 5750 26.0 78.8 320 2 1 13.9 7.6 | 26.1 79.0 345 5 3 10.8 5.9 5500 27.5 81.5 325 3 1 28.0 15.3 | 27.0 80.6 345 5 2 13.8 7.6 ________________________________________________________________________________ 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