685 UXUS97 KBOU 011315 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0713 MDT Friday, August 1, 2025 This forecast is for Friday, August 1, 2025: If the trigger temperature of 81.8 F/27.7 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1081 ft/min (5.5 m/s) Maximum height of thermals.................. 17000 ft MSL (11677 ft AGL) Forecast maximum temperature................... 89.0 F/32.1 C Time of trigger temperature.................... 1045 MDT Time of overdevelopment........................ 1700 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 10404 ft MSL (5080 ft AGL) Thermal soaring outlook for Saturday 08/02..... Excellent Wave Soaring Index............................. Poor Wave Soaring Index trend (to 1800 MDT)......... Height of stable layer (12-18K ft MSL)......... None Weak PVA/NVA (through 1800 MDT)................ Neither Potential height of wave....................... 14441 ft MSL (9118 ft AGL) Wave soaring outlook for Saturday 08/02........ Poor Remarks... Sunrise/Sunset.................... 05:59:04 / 20:12:32 MDT Total possible sunshine........... 14 hr 13 min 27 sec (853 min 27 sec) Altitude of sun at 13:05:48 MDT... 68.00 degrees Upper air data from numerical model forecast valid on 08/01/2025 at 0600 MDT Freezing level.................. 15762 ft MSL (10439 ft AGL) Convective condensation level... 15619 ft MSL (10296 ft AGL) Lifted condensation level....... 15879 ft MSL (10556 ft AGL) Lifted index.................... -5.6 K index......................... +21.6 Height Temperature Wind Wind Spd Lapse Rate ConvectionT Thermal Lift Rate ft MSL deg C deg F Dir kt m/s C/km F/kft deg C deg F Index fpm m/s -------------------------------------------------------------------------------- 50000 -60.2 -76.4 265 27 14 3.8 2.1 M M M M M 45000 -54.7 -66.5 255 43 22 3.3 1.8 M M M M M 40000 -49.6 -57.3 245 58 30 3.8 2.1 M M M M M 38000 -47.3 -53.1 240 60 31 3.8 2.1 M M M M M 36000 -44.7 -48.5 240 63 33 4.0 2.2 M M M M M 34000 -41.4 -42.5 240 59 30 5.7 3.1 M M M M M 32000 -37.9 -36.2 245 54 28 5.6 3.1 M M M M M 30000 -34.1 -29.4 245 45 23 6.5 3.6 41.1 106.0 7.2 M M 29000 -32.1 -25.8 250 40 20 6.6 3.6 39.9 103.8 6.3 M M 28000 -30.1 -22.2 250 35 18 7.5 4.1 38.9 101.9 5.5 M M 27000 -27.8 -18.0 250 32 16 7.7 4.2 38.0 100.3 4.9 M M 26000 -25.5 -13.9 255 29 15 7.7 4.2 37.2 98.9 4.3 M M 25000 -23.2 -9.8 255 26 14 8.0 4.4 36.6 97.8 3.8 M M 24000 -20.7 -5.3 260 24 12 8.6 4.7 36.0 96.8 3.4 M M 23000 -18.1 -0.6 270 22 11 8.6 4.7 35.6 96.0 3.1 M M 22000 -15.5 4.1 275 20 10 8.0 4.4 35.2 95.4 2.9 M M 21000 -13.3 8.1 275 15 8 7.4 4.1 34.3 93.8 2.1 M M 20000 -11.1 12.0 280 10 5 7.5 4.1 33.5 92.3 1.4 M M 19500 -10.0 14.0 280 8 4 7.5 4.1 33.2 91.7 1.1 M M 19000 -8.8 16.2 285 7 4 8.6 4.7 32.9 91.2 0.9 M M 18500 -6.9 19.6 295 7 4 8.5 4.7 32.6 90.6 0.5 M M 18000 -5.7 21.7 300 7 4 8.8 4.8 32.4 90.3 0.3 M M 17500 -4.4 24.1 300 8 4 8.8 4.8 32.2 90.0 0.1 M M 17000 -3.1 26.4 305 8 4 9.0 4.9 32.1 89.7 -0.0 1071 5.4 16500 -1.8 28.8 300 9 5 9.1 5.0 31.9 89.5 -0.2 1015 5.2 16000 -0.4 31.3 300 10 5 9.1 5.0 31.8 89.3 -0.3 960 4.9 15500 0.9 33.6 300 11 6 9.1 5.0 31.7 89.1 -0.4 905 4.6 15000 2.2 36.0 300 12 6 9.1 5.0 31.6 88.9 -0.5 851 4.3 14500 3.6 38.5 295 13 7 9.6 5.3 31.5 88.7 -0.6 795 4.0 14000 5.0 41.0 295 14 7 9.6 5.3 31.5 88.7 -0.7 739 3.8 13500 6.3 43.3 290 14 7 8.6 4.7 31.4 88.5 -0.9 684 3.5 13000 7.5 45.5 285 13 7 8.6 4.7 31.2 88.2 -1.1 633 3.2 12500 8.7 47.7 280 13 6 7.9 4.3 31.0 87.8 -1.4 583 3.0 12000 9.8 49.6 275 12 6 7.7 4.2 30.7 87.2 -1.8 535 2.7 11500 10.9 51.6 270 11 6 7.9 4.4 30.3 86.6 -2.1 487 2.5 11000 12.1 53.8 260 11 6 8.0 4.4 30.1 86.1 -2.4 437 2.2 10500 13.2 55.8 255 10 5 4.1 2.3 29.7 85.5 -2.8 389 2.0 10250 13.4 56.1 255 10 5 4.8 2.6 29.2 84.5 -3.3 375 1.9 10000 14.0 57.2 250 11 5 10.1 5.5 29.1 84.4 -3.4 349 1.8 9750 14.8 58.6 245 11 6 9.8 5.3 29.1 84.4 -3.4 320 1.6 9500 15.4 59.7 240 12 6 6.5 3.6 29.0 84.2 -3.5 293 1.5 9250 15.7 60.3 235 12 6 4.1 2.2 28.6 83.5 -3.9 276 1.4 9000 16.1 61.0 230 13 7 5.9 3.2 28.2 82.8 -4.3 258 1.3 8750 16.5 61.7 225 14 7 6.3 3.4 28.0 82.4 -4.6 237 1.2 8500 16.9 62.4 220 15 8 4.5 2.5 27.6 81.8 -5.0 219 1.1 8250 17.1 62.8 215 16 8 3.7 2.1 27.2 81.0 -5.5 204 1.0 8000 17.4 63.3 215 17 9 4.4 2.4 26.8 80.2 -6.0 189 1.0 7750 17.7 63.9 210 18 9 3.7 2.0 26.3 79.4 -6.5 173 0.9 7500 17.9 64.2 210 18 9 2.3 1.3 25.8 78.5 -7.0 160 0.8 7250 18.0 64.4 205 18 9 1.9 1.1 25.2 77.4 -7.6 148 0.8 7000 18.2 64.8 205 18 9 2.5 1.4 24.6 76.3 -8.2 137 0.7 6750 18.3 64.9 200 18 9 -0.2 -0.1 24.0 75.3 -8.8 126 0.6 6500 18.1 64.6 200 17 9 -2.8 -1.5 23.1 73.6 -9.8 124 0.6 6250 17.9 64.2 200 16 8 -1.6 -0.9 22.2 72.0 -10.7 122 0.6 6000 17.7 63.9 200 16 8 -3.9 -2.2 21.3 70.4 -11.7 120 0.6 5750 17.2 63.0 195 13 7 -7.3 -4.0 20.1 68.2 -13.0 129 0.7 5500 16.6 61.9 195 9 5 -6.4 -3.5 18.9 65.9 -14.4 140 0.7 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 08/01/2025 at 0900 MDT | 08/01/2025 at 1200 MDT | CAPE... +448.9 LI... -0.4 | CAPE... +845.6 LI... -2.5 CINH... -280.4 K Index... +13.9 | CINH... -17.3 K Index... +9.8 | 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 -59.3 -74.7 260 22 11 4.3 2.3 | -59.1 -74.4 265 22 11 4.1 2.3 45000 -53.5 -64.3 255 39 20 3.1 1.7 | -53.6 -64.5 260 37 19 2.8 1.6 40000 -48.6 -55.5 250 60 31 2.7 1.5 | -49.1 -56.4 260 57 30 2.7 1.5 38000 -47.0 -52.6 250 62 32 2.7 1.5 | -47.5 -53.5 260 55 28 2.7 1.5 36000 -45.3 -49.5 245 63 33 2.6 1.4 | -45.8 -50.4 265 53 27 2.5 1.4 34000 -42.7 -44.9 250 56 29 4.7 2.6 | -43.0 -45.4 265 45 23 5.1 2.8 32000 -39.9 -39.8 250 48 24 4.6 2.5 | -39.9 -39.8 265 37 19 5.0 2.7 30000 -35.6 -32.1 250 41 21 7.7 4.2 | -35.3 -31.5 265 32 16 8.3 4.6 29000 -33.3 -27.9 250 39 20 7.7 4.3 | -32.8 -27.0 265 30 15 8.3 4.6 28000 -31.0 -23.8 250 36 18 7.6 4.2 | -30.3 -22.5 265 28 14 7.5 4.1 27000 -28.7 -19.7 250 32 16 7.5 4.1 | -27.8 -18.0 265 24 13 6.8 3.7 26000 -26.0 -14.8 255 27 14 7.5 4.1 | -25.8 -14.4 260 22 11 6.8 3.7 25000 -23.7 -10.7 255 23 12 8.5 4.7 | -23.7 -10.7 255 20 10 8.3 4.5 24000 -20.9 -5.6 260 21 11 9.2 5.0 | -21.0 -5.8 255 18 9 9.0 4.9 23000 -18.2 -0.8 260 18 9 9.2 5.0 | -18.3 -0.9 260 16 8 9.0 5.0 22000 -15.5 4.1 265 15 8 8.1 4.4 | -15.7 3.7 260 15 8 8.1 4.4 21000 -13.2 8.2 255 13 7 7.8 4.3 | -13.3 8.1 260 15 7 8.0 4.4 20000 -10.9 12.4 250 10 5 7.9 4.3 | -10.9 12.4 265 14 7 8.0 4.4 19500 -9.7 14.5 240 9 5 7.8 4.3 | -9.8 14.4 265 14 7 8.2 4.5 19000 -8.5 16.7 240 8 4 7.8 4.3 | -8.5 16.7 265 13 7 8.5 4.7 18500 -7.4 18.7 240 6 3 7.8 4.3 | -7.3 18.9 265 12 6 8.6 4.7 18000 -6.2 20.8 245 5 3 8.3 4.5 | -6.0 21.2 270 11 6 8.2 4.5 17500 -5.0 23.0 255 5 2 8.4 4.6 | -4.8 23.4 270 10 5 8.2 4.5 17000 -3.8 25.2 270 4 2 8.7 4.8 | -3.7 25.3 270 10 5 8.6 4.7 16500 -2.5 27.5 280 4 2 9.3 5.1 | -2.3 27.9 275 9 5 9.0 5.0 16000 -1.1 30.0 295 5 2 9.4 5.1 | -1.0 30.2 275 9 4 9.1 5.0 15500 0.3 32.5 300 5 3 9.1 5.0 | 0.4 32.7 280 9 4 9.2 5.0 15000 1.6 34.9 300 6 3 9.1 5.0 | 1.7 35.1 280 9 5 9.2 5.0 14500 3.0 37.4 300 7 4 9.3 5.1 | 3.1 37.6 285 9 5 9.4 5.2 14000 4.4 39.9 295 8 4 9.3 5.1 | 4.5 40.1 290 10 5 9.4 5.2 13500 5.8 42.4 295 9 5 9.2 5.1 | 5.9 42.6 295 10 5 9.6 5.3 13000 7.8 46.0 295 11 6 9.1 5.0 | 8.1 46.6 295 11 5 9.7 5.3 12500 9.2 48.6 295 12 6 9.5 5.2 | 9.5 49.1 295 11 6 9.0 4.9 12000 10.6 51.1 290 14 7 9.6 5.2 | 10.8 51.4 295 11 6 9.0 4.9 11500 12.0 53.6 290 15 8 9.3 5.1 | 12.2 54.0 300 12 6 9.8 5.4 11000 13.3 55.9 285 16 8 9.5 5.2 | 13.7 56.7 300 13 6 10.3 5.7 10500 14.4 57.9 285 17 9 2.5 1.3 | 14.8 58.6 300 13 7 3.1 1.7 10250 14.6 58.3 285 17 9 7.5 4.1 | 15.1 59.2 300 13 7 8.4 4.6 10000 15.5 59.9 285 17 9 14.8 8.1 | 16.0 60.8 300 14 7 14.3 7.8 9750 16.5 61.7 285 16 8 11.1 6.1 | 17.0 62.6 300 14 7 10.4 5.7 9500 17.1 62.8 285 16 8 7.4 4.1 | 17.5 63.5 295 14 7 6.2 3.4 9250 17.6 63.7 285 16 8 6.4 3.5 | 17.9 64.2 295 14 7 6.3 3.4 9000 18.2 64.8 285 15 8 9.8 5.4 | 18.5 65.3 295 14 7 10.1 5.5 8750 18.9 66.0 285 15 8 9.6 5.3 | 19.2 66.6 295 13 7 9.8 5.4 8500 19.4 66.9 285 14 7 6.7 3.7 | 19.7 67.5 295 11 6 7.4 4.1 8250 19.9 67.8 285 13 7 6.1 3.4 | 20.2 68.4 295 9 5 7.0 3.9 8000 20.4 68.7 285 13 7 7.6 4.2 | 20.7 69.3 295 7 4 9.1 5.0 7750 20.9 69.6 285 12 6 5.6 3.1 | 21.4 70.5 300 5 3 10.4 5.7 7500 21.1 70.0 285 11 6 2.6 1.4 | 22.1 71.8 305 5 3 9.3 5.1 7250 21.3 70.3 280 11 5 3.0 1.6 | 22.7 72.9 305 5 2 9.4 5.1 7000 21.5 70.7 280 10 5 3.8 2.1 | 23.4 74.1 310 4 2 10.4 5.7 6750 21.6 70.9 275 9 4 -2.0 -1.1 | 24.2 75.6 315 4 2 10.8 5.9 6500 21.1 70.0 260 7 3 -6.4 -3.5 | 25.0 77.0 315 4 2 10.0 5.5 6250 20.6 69.1 235 5 3 -7.3 -4.0 | 25.7 78.3 315 4 2 10.0 5.5 6000 20.0 68.0 205 6 3 1.2 0.7 | 26.5 79.7 315 4 2 10.7 5.9 5750 20.7 69.3 205 6 3 14.7 8.1 | 27.4 81.3 315 4 2 17.7 9.7 5500 21.7 71.1 195 6 3 10.0 5.5 | 29.1 84.4 320 4 2 26.6 14.6 08/01/2025 at 1500 MDT | 08/01/2025 at 1800 MDT | CAPE... +383.2 LI... -0.8 | CAPE... +5.4 LI... +1.4 CINH... -10.3 K Index... +19.4 | CINH... -1.5 K Index... +21.7 | 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 -59.9 -75.8 280 29 15 2.4 1.3 | -59.7 -75.5 285 30 16 2.3 1.2 45000 -55.4 -67.7 275 49 25 4.2 2.3 | -55.7 -68.3 280 50 26 3.4 1.9 40000 -49.0 -56.2 265 61 31 2.7 1.5 | -50.2 -58.4 270 53 27 3.6 2.0 38000 -47.4 -53.3 265 62 32 2.7 1.5 | -48.1 -54.6 270 49 25 3.6 2.0 36000 -45.8 -50.4 265 64 33 2.3 1.2 | -46.0 -50.8 270 46 24 3.7 2.1 34000 -42.4 -44.3 265 57 29 6.1 3.4 | -42.0 -43.6 265 37 19 6.8 3.8 32000 -38.7 -37.7 270 48 25 6.0 3.3 | -37.9 -36.2 250 30 15 6.7 3.7 30000 -34.5 -30.1 270 38 20 7.2 4.0 | -33.1 -27.6 240 26 14 8.3 4.5 29000 -32.4 -26.3 270 34 17 7.2 4.0 | -30.1 -22.2 235 25 13 8.3 4.6 28000 -29.6 -21.3 270 29 15 7.4 4.1 | -27.6 -17.7 230 24 12 8.3 4.6 27000 -27.4 -17.3 270 27 14 7.4 4.1 | -25.1 -13.2 230 23 12 8.3 4.6 26000 -25.2 -13.4 270 25 13 7.4 4.1 | -22.6 -8.7 230 22 11 8.4 4.6 25000 -23.0 -9.4 270 23 12 7.9 4.3 | -20.2 -4.4 235 21 11 7.7 4.2 24000 -20.6 -5.1 270 22 11 8.1 4.5 | -18.0 -0.4 235 19 10 7.4 4.1 23000 -18.2 -0.8 265 21 11 8.2 4.5 | -15.8 3.6 240 16 8 7.5 4.1 22000 -15.8 3.6 265 20 10 8.6 4.7 | -13.6 7.5 250 14 7 7.7 4.2 21000 -13.2 8.2 275 20 10 8.7 4.7 | -11.3 11.7 260 13 7 7.8 4.3 20000 -10.7 12.7 280 20 10 8.7 4.8 | -9.0 15.8 270 11 6 7.8 4.3 19500 -9.4 15.1 285 20 10 8.5 4.7 | -7.9 17.8 280 11 6 7.9 4.3 19000 -8.1 17.4 285 19 10 8.3 4.6 | -6.7 19.9 280 10 5 8.2 4.5 18500 -6.9 19.6 290 19 10 8.3 4.6 | -5.5 22.1 285 9 5 8.2 4.5 18000 -5.7 21.7 290 18 9 9.0 4.9 | -4.3 24.3 285 8 4 7.8 4.3 17500 -4.3 24.3 295 17 9 9.0 5.0 | -3.2 26.2 290 7 4 7.7 4.2 17000 -3.0 26.6 295 16 8 9.2 5.0 | -2.1 28.2 295 6 3 7.5 4.1 16500 -1.6 29.1 295 15 8 9.4 5.2 | -1.0 30.2 300 6 3 6.9 3.8 16000 -0.2 31.6 295 14 7 9.4 5.2 | -0.0 32.0 310 6 3 7.0 3.8 15500 1.1 34.0 295 13 7 8.8 4.8 | 0.9 33.6 315 6 3 6.6 3.6 15000 2.4 36.3 300 11 6 8.9 4.9 | 1.9 35.4 320 6 3 6.6 3.6 14500 3.8 38.8 300 10 5 9.1 5.0 | 3.4 38.1 320 6 3 7.9 4.3 14000 5.8 42.4 300 8 4 9.1 5.0 | 4.5 40.1 325 7 4 7.8 4.3 13500 7.1 44.8 305 6 3 9.3 5.1 | 5.7 42.3 320 7 4 8.3 4.6 13000 8.5 47.3 315 5 2 9.4 5.1 | 6.9 44.4 320 8 4 8.2 4.5 12500 9.8 49.6 330 4 2 9.1 5.0 | 8.2 46.8 315 8 4 9.0 4.9 12000 11.2 52.2 350 3 2 9.1 5.0 | 9.6 49.3 310 9 4 9.0 4.9 11500 12.5 54.5 005 3 2 9.6 5.3 | 10.9 51.6 310 9 5 9.3 5.1 11000 13.9 57.0 015 3 2 10.1 5.5 | 12.3 54.1 305 10 5 9.6 5.3 10500 15.0 59.0 020 3 2 3.8 2.1 | 13.5 56.3 300 10 5 3.2 1.8 10250 15.4 59.7 020 3 2 9.2 5.0 | 13.8 56.8 300 10 5 7.0 3.8 10000 16.4 61.5 025 3 2 14.4 7.9 | 14.6 58.3 295 11 6 13.1 7.2 9750 17.3 63.1 025 3 2 11.6 6.3 | 15.5 59.9 290 11 6 10.1 5.6 9500 18.1 64.6 025 3 2 8.2 4.5 | 16.2 61.2 285 12 6 6.5 3.6 9250 18.7 65.7 030 3 2 8.5 4.7 | 16.6 61.9 285 12 6 5.5 3.0 9000 19.4 66.9 030 3 2 12.2 6.7 | 17.1 62.8 280 12 6 9.9 5.5 8750 20.4 68.7 030 3 2 11.6 6.4 | 17.9 64.2 280 13 7 10.2 5.6 8500 21.1 70.0 030 3 2 9.2 5.0 | 18.5 65.3 275 14 7 6.9 3.8 8250 21.8 71.2 030 4 2 8.5 4.7 | 19.0 66.2 270 14 7 6.3 3.4 8000 22.4 72.3 030 4 2 10.3 5.7 | 19.5 67.1 270 15 8 7.2 3.9 7750 23.3 73.9 030 4 2 11.0 6.0 | 20.1 68.2 265 16 8 8.2 4.5 7500 24.0 75.2 030 4 2 9.7 5.3 | 20.7 69.3 265 16 8 8.2 4.5 7250 24.8 76.6 030 4 2 9.7 5.3 | 21.3 70.3 260 16 8 8.2 4.5 7000 25.5 77.9 030 4 2 10.7 5.9 | 21.9 71.4 260 17 9 8.2 4.5 6750 26.3 79.3 030 4 2 10.9 6.0 | 22.5 72.5 260 17 9 9.3 5.1 6500 27.1 80.8 030 4 2 10.1 5.5 | 23.3 73.9 260 17 9 10.3 5.6 6250 27.8 82.0 030 4 2 10.0 5.5 | 24.0 75.2 255 17 9 9.5 5.2 6000 28.6 83.5 030 4 2 11.3 6.2 | 24.8 76.6 255 17 9 11.5 6.3 5750 29.7 85.5 030 4 2 18.6 10.2 | 25.8 78.4 255 16 8 15.9 8.7 5500 31.4 88.5 035 4 2 26.1 14.3 | 27.0 80.6 255 14 7 17.8 9.8 ________________________________________________________________________________ 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. CINH (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