


Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
030 UXUS97 KBOU 020118 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1915 MDT Friday, August 1, 2025 This forecast is for Saturday, August 2, 2025: If the trigger temperature of 84.6 F/29.2 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1293 ft/min (6.6 m/s) Maximum height of thermals.................. 18519 ft MSL (13220 ft AGL) Forecast maximum temperature................... 90.0 F/32.7 C Time of trigger temperature.................... 1100 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................. 9226 ft MSL (3927 ft AGL) Thermal soaring outlook for Sunday 08/03....... Excellent Wave Soaring Index............................. Poor Wave Soaring Index trend (to 1800 MDT)......... No change Height of stable layer (12-18K ft MSL)......... None Weak PVA/NVA (through 1800 MDT)................ Neither Potential height of wave....................... 40566 ft MSL (35267 ft AGL) Wave soaring outlook for Sunday 08/03.......... Poor Remarks... Sunrise/Sunset.................... 06:00:00 / 20:11:28 MDT Total possible sunshine........... 14 hr 11 min 28 sec (851 min 28 sec) Altitude of sun at 13:05:44 MDT... 67.74 degrees Upper air data from numerical model forecast valid on 08/02/2025 at 0600 MDT Freezing level.................. 15665 ft MSL (10366 ft AGL) Convective condensation level... 16963 ft MSL (11664 ft AGL) Lifted condensation level....... 17347 ft MSL (12048 ft AGL) Lifted index.................... -3.1 K index......................... +18.0 Height Temperature Wind Wind Spd Lapse Rate ConvectionT Thermal Lift Rate ft MSL deg C deg F Dir kt m/s C/km F/kft deg C deg F Index fpm m/s -------------------------------------------------------------------------------- 50000 -60.8 -77.4 270 29 15 3.4 1.9 M M M M M 45000 -55.1 -67.2 275 51 26 4.5 2.4 M M M M M 40000 -48.7 -55.7 280 66 34 2.9 1.6 M M M M M 38000 -47.0 -52.6 280 67 34 2.9 1.6 M M M M M 36000 -45.0 -49.0 285 67 35 3.8 2.1 M M M M M 34000 -40.9 -41.6 285 63 33 7.2 3.9 M M M M M 32000 -36.6 -33.9 285 59 30 7.3 4.0 M M M M M 30000 -32.6 -26.7 285 52 27 6.6 3.6 42.9 109.2 8.1 M M 29000 -30.6 -23.1 285 49 25 6.6 3.6 41.7 107.1 7.3 M M 28000 -28.6 -19.5 285 46 24 7.1 3.9 40.7 105.2 6.6 M M 27000 -26.4 -15.5 285 42 21 7.2 3.9 39.6 103.2 5.8 M M 26000 -24.3 -11.7 285 37 19 7.2 4.0 38.6 101.5 5.1 M M 25000 -22.1 -7.8 285 33 17 7.4 4.1 37.8 100.0 4.4 M M 24000 -19.8 -3.6 285 31 16 7.9 4.3 36.9 98.5 3.8 M M 23000 -17.5 0.5 290 29 15 7.9 4.3 36.3 97.3 3.2 M M 22000 -15.1 4.8 295 27 14 7.4 4.1 35.7 96.2 2.8 M M 21000 -13.1 8.4 295 24 12 7.0 3.9 34.6 94.3 1.8 M M 20000 -11.0 12.2 300 21 11 7.1 3.9 33.7 92.6 1.0 M M 19500 -10.0 14.0 305 20 10 7.2 3.9 33.2 91.8 0.6 M M 19000 -8.8 16.2 305 19 10 8.2 4.5 32.9 91.2 0.3 M M 18500 -7.6 18.3 305 17 9 8.1 4.5 32.6 90.7 0.1 M M 18000 -5.8 21.6 305 16 8 8.6 4.7 32.3 90.1 -0.3 1226 6.2 17500 -4.5 23.9 305 15 8 8.6 4.7 32.0 89.7 -0.5 1173 6.0 17000 -3.2 26.2 305 15 7 8.8 4.8 31.9 89.4 -0.7 1120 5.7 16500 -1.9 28.6 300 14 7 8.8 4.8 31.7 89.1 -0.9 1066 5.4 16000 -0.7 30.7 300 13 7 9.0 4.9 31.6 88.8 -1.0 1013 5.1 15500 0.7 33.3 300 12 6 9.3 5.1 31.4 88.6 -1.2 957 4.9 15000 2.1 35.8 295 12 6 9.3 5.1 31.4 88.5 -1.3 901 4.6 14500 3.5 38.3 295 12 6 9.5 5.2 31.3 88.4 -1.3 845 4.3 14000 4.9 40.8 295 12 6 9.4 5.2 31.3 88.3 -1.4 788 4.0 13500 6.3 43.3 295 12 6 9.6 5.3 31.2 88.2 -1.5 731 3.7 13000 7.7 45.9 295 12 6 9.6 5.3 31.2 88.2 -1.5 673 3.4 12500 9.1 48.4 295 12 6 9.6 5.3 31.2 88.1 -1.5 615 3.1 12000 10.6 51.1 295 12 6 9.6 5.3 31.2 88.1 -1.6 557 2.8 11500 12.0 53.6 290 12 6 9.0 5.0 31.1 88.0 -1.6 500 2.5 11000 13.3 55.9 290 12 6 8.8 4.8 31.0 87.7 -1.8 446 2.3 10500 14.5 58.1 290 12 6 5.3 2.9 30.7 87.3 -2.1 395 2.0 10250 14.8 58.6 290 12 6 6.5 3.6 30.3 86.6 -2.5 378 1.9 10000 15.5 59.9 285 12 6 10.8 5.9 30.3 86.6 -2.5 349 1.8 9750 16.3 61.3 285 12 6 9.9 5.4 30.4 86.6 -2.5 319 1.6 9500 16.9 62.4 280 11 6 6.7 3.7 30.3 86.5 -2.6 293 1.5 9250 17.3 63.1 280 11 6 4.3 2.4 29.9 85.8 -3.0 275 1.4 9000 17.7 63.9 275 11 5 8.5 4.7 29.6 85.3 -3.3 255 1.3 8750 18.4 65.1 270 10 5 9.7 5.3 29.6 85.3 -3.3 226 1.1 8500 19.0 66.2 265 10 5 5.4 3.0 29.5 85.0 -3.5 202 1.0 8250 19.3 66.7 265 9 5 3.4 1.9 29.0 84.2 -4.0 186 0.9 8000 19.5 67.1 260 9 4 6.0 3.3 28.6 83.5 -4.4 170 0.9 7750 20.0 68.0 255 8 4 5.0 2.8 28.4 83.0 -4.7 149 0.8 7500 20.1 68.2 250 8 4 0.2 0.1 27.8 82.0 -5.3 138 0.7 7250 20.1 68.2 250 8 4 -0.5 -0.3 27.0 80.6 -6.1 132 0.7 7000 20.0 68.0 245 8 4 -0.1 -0.1 26.2 79.2 -6.9 127 0.6 6750 19.9 67.8 240 7 4 -4.6 -2.5 25.4 77.7 -7.8 124 0.6 6500 19.2 66.6 235 7 4 -7.6 -4.2 24.1 75.3 -9.2 135 0.7 6250 18.6 65.5 230 7 4 -7.5 -4.1 22.8 73.0 -10.6 146 0.7 6000 18.0 64.4 225 7 3 -4.5 -2.5 21.5 70.8 -11.9 157 0.8 5750 17.7 63.9 220 6 3 -6.6 -3.6 20.5 68.9 -13.0 159 0.8 5500 16.7 62.1 210 5 3 -19.6 -10.7 18.8 65.8 -14.8 183 0.9 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 08/02/2025 at 0900 MDT | 08/02/2025 at 1200 MDT | CAPE... +102.6 LI... +0.2 | CAPE... +164.4 LI... -0.5 CINH... -166.3 K Index... +17.9 | CINH... -14.7 K Index... +20.3 | 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 -60.2 -76.4 275 30 15 2.9 1.6 | -59.9 -75.8 275 29 15 3.3 1.8 45000 -55.3 -67.5 275 54 28 4.1 2.2 | -54.8 -66.6 275 53 27 3.7 2.0 40000 -49.3 -56.7 275 67 34 3.1 1.7 | -49.3 -56.7 275 66 34 2.8 1.5 38000 -47.4 -53.3 280 67 35 3.1 1.7 | -47.7 -53.9 275 68 35 2.8 1.5 36000 -45.4 -49.7 280 69 35 3.7 2.0 | -45.8 -50.4 275 69 36 3.3 1.8 34000 -41.5 -42.7 280 64 33 6.6 3.6 | -42.0 -43.6 275 65 33 6.6 3.6 32000 -37.5 -35.5 280 58 30 6.7 3.7 | -38.0 -36.4 275 60 31 6.7 3.7 30000 -33.2 -27.8 280 51 26 7.4 4.0 | -33.4 -28.1 275 50 26 7.9 4.3 29000 -31.0 -23.8 280 47 24 7.4 4.0 | -31.0 -23.8 275 45 23 7.9 4.3 28000 -28.8 -19.8 280 43 22 6.9 3.8 | -28.7 -19.7 275 41 21 6.8 3.7 27000 -26.7 -16.1 280 39 20 6.9 3.8 | -26.7 -16.1 275 38 19 6.7 3.7 26000 -24.7 -12.5 280 34 18 6.9 3.8 | -24.7 -12.5 275 35 18 6.7 3.7 25000 -22.6 -8.7 280 30 16 7.1 3.9 | -22.7 -8.9 275 32 16 6.8 3.8 24000 -20.4 -4.7 280 27 14 7.6 4.2 | -20.7 -5.3 280 29 15 7.1 3.9 23000 -18.1 -0.6 285 24 13 7.6 4.2 | -18.6 -1.5 280 27 14 7.1 3.9 22000 -15.9 3.4 285 22 11 7.6 4.2 | -16.5 2.3 280 24 12 8.0 4.4 21000 -13.6 7.5 285 20 10 7.6 4.2 | -14.0 6.8 280 22 11 8.6 4.7 20000 -11.4 11.5 290 18 9 7.6 4.2 | -11.5 11.3 280 20 10 8.6 4.7 19500 -10.3 13.5 290 17 9 7.8 4.3 | -10.2 13.6 280 19 10 8.6 4.7 19000 -8.4 16.9 290 16 8 8.5 4.7 | -9.0 15.8 280 18 9 8.4 4.6 18500 -7.1 19.2 290 15 8 8.6 4.7 | -7.7 18.1 275 17 9 8.4 4.6 18000 -5.9 21.4 290 14 7 8.7 4.8 | -5.8 21.6 275 15 8 9.2 5.0 17500 -4.6 23.7 295 13 7 8.7 4.7 | -4.4 24.1 275 15 8 9.1 5.0 17000 -3.3 26.1 295 13 7 9.1 5.0 | -3.1 26.4 275 14 7 9.1 5.0 16500 -1.9 28.6 295 12 6 9.2 5.1 | -1.7 28.9 275 13 7 9.1 5.0 16000 -0.6 30.9 300 12 6 9.3 5.1 | -0.3 31.5 275 12 6 9.2 5.1 15500 0.8 33.4 300 11 6 9.3 5.1 | 1.1 34.0 270 12 6 9.4 5.2 15000 2.2 36.0 300 11 6 9.3 5.1 | 2.5 36.5 270 11 6 9.5 5.2 14500 3.6 38.5 300 10 5 9.4 5.1 | 3.9 39.0 270 10 5 9.5 5.2 14000 5.0 41.0 300 10 5 9.4 5.1 | 5.3 41.5 270 9 5 9.5 5.2 13500 6.3 43.3 300 9 5 9.4 5.1 | 6.7 44.1 270 9 4 9.4 5.1 13000 7.7 45.9 300 9 5 9.4 5.1 | 8.1 46.6 265 8 4 9.4 5.1 12500 9.1 48.4 295 9 5 9.3 5.1 | 9.5 49.1 265 7 4 9.6 5.2 12000 10.5 50.9 295 9 5 9.4 5.1 | 11.0 51.8 265 7 3 9.6 5.3 11500 11.9 53.4 295 9 5 9.2 5.1 | 12.4 54.3 260 6 3 9.4 5.2 11000 13.3 55.9 295 9 5 9.2 5.0 | 13.8 56.8 260 6 3 9.5 5.2 10500 14.5 58.1 290 9 5 3.6 2.0 | 15.0 59.0 255 5 3 3.6 2.0 10250 14.7 58.5 295 9 5 6.9 3.8 | 15.3 59.5 250 4 2 7.6 4.2 10000 15.6 60.1 290 9 4 13.4 7.4 | 16.2 61.2 250 4 2 14.1 7.7 9750 16.5 61.7 290 9 4 11.2 6.1 | 17.2 63.0 250 4 2 11.8 6.5 9500 17.2 63.0 285 8 4 7.8 4.3 | 17.9 64.2 250 4 2 8.0 4.4 9250 17.7 63.9 285 8 4 5.8 3.2 | 18.4 65.1 245 3 2 6.8 3.7 9000 18.2 64.8 285 8 4 9.8 5.4 | 19.1 66.4 240 3 2 11.3 6.2 8750 19.0 66.2 280 8 4 10.5 5.8 | 20.0 68.0 240 3 2 11.4 6.3 8500 19.7 67.5 275 8 4 7.4 4.1 | 20.7 69.3 235 3 2 8.5 4.6 8250 20.2 68.4 270 7 4 5.9 3.2 | 21.3 70.3 220 3 1 6.3 3.5 8000 20.6 69.1 270 7 4 8.4 4.6 | 21.8 71.2 205 2 1 10.5 5.8 7750 21.3 70.3 265 7 4 7.7 4.2 | 22.7 72.9 205 2 1 12.0 6.6 7500 21.7 71.1 260 7 4 3.8 2.1 | 23.4 74.1 195 2 1 8.3 4.6 7250 21.9 71.4 255 7 4 2.8 1.5 | 24.0 75.2 185 2 1 6.7 3.7 7000 22.2 72.0 250 7 4 5.3 2.9 | 24.6 76.3 180 2 1 11.9 6.5 6750 22.5 72.5 245 7 4 2.2 1.2 | 25.7 78.3 180 2 1 13.4 7.3 6500 22.4 72.3 245 7 3 -2.4 -1.3 | 26.5 79.7 175 2 1 9.3 5.1 6250 22.2 72.0 240 6 3 -1.2 -0.6 | 27.2 81.0 170 2 1 10.7 5.9 6000 22.0 71.6 235 6 3 -1.1 -0.6 | 28.0 82.4 165 2 1 9.1 5.0 5750 22.1 71.8 225 5 2 6.2 3.4 | 28.8 83.8 155 2 1 15.1 8.3 5500 22.9 73.2 220 4 2 16.7 9.2 | 30.4 86.7 150 2 1 28.3 15.6 08/02/2025 at 1500 MDT | 08/02/2025 at 1800 MDT | CAPE... +38.4 LI... +0.1 | CAPE... +186.4 LI... -0.4 CINH... -23.3 K Index... +26.9 | CINH... -122.7 K Index... +26.6 | 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 -75.3 275 31 16 3.2 1.8 | -59.3 -74.7 275 28 14 3.0 1.7 45000 -54.8 -66.6 275 54 28 3.1 1.7 | -54.4 -65.9 275 47 24 3.6 2.0 40000 -50.1 -58.2 270 71 37 2.6 1.4 | -49.2 -56.6 265 59 30 2.3 1.3 38000 -48.4 -55.1 265 62 32 2.6 1.4 | -47.8 -54.0 270 53 27 2.3 1.3 36000 -46.8 -52.2 265 54 28 3.6 2.0 | -46.2 -51.2 275 46 24 2.7 1.5 34000 -42.2 -44.0 265 48 24 8.0 4.4 | -42.1 -43.8 275 42 22 7.3 4.0 32000 -37.3 -35.1 265 42 21 8.6 4.7 | -37.7 -35.9 275 39 20 7.2 3.9 30000 -32.3 -26.1 265 36 19 8.5 4.7 | -32.9 -27.2 270 37 19 8.0 4.4 29000 -29.7 -21.5 265 33 17 8.6 4.7 | -30.6 -23.1 270 37 19 8.0 4.4 28000 -27.2 -17.0 265 30 16 7.9 4.3 | -28.2 -18.8 265 36 19 8.2 4.5 27000 -24.9 -12.8 265 28 15 7.9 4.3 | -25.7 -14.3 265 35 18 8.2 4.5 26000 -22.6 -8.7 265 26 14 7.9 4.3 | -23.2 -9.8 260 35 18 8.2 4.5 25000 -20.2 -4.4 265 24 13 7.8 4.3 | -20.8 -5.4 260 34 18 7.9 4.3 24000 -18.0 -0.4 270 22 11 7.5 4.1 | -18.7 -1.7 255 35 18 6.7 3.7 23000 -15.8 3.6 270 20 10 7.5 4.1 | -16.8 1.8 255 37 19 6.7 3.7 22000 -13.6 7.5 270 17 9 7.0 3.8 | -14.8 5.4 255 39 20 7.2 4.0 21000 -11.8 10.8 270 14 7 6.3 3.4 | -12.5 9.5 260 38 20 8.0 4.4 20000 -9.5 14.9 275 10 5 6.3 3.5 | -10.1 13.8 260 38 19 8.1 4.4 19500 -8.6 16.5 275 8 4 6.0 3.3 | -9.0 15.8 260 37 19 8.1 4.4 19000 -7.8 18.0 270 7 3 5.8 3.2 | -7.8 18.0 260 36 19 8.6 4.7 18500 -6.9 19.6 265 5 3 5.7 3.1 | -5.9 21.4 260 34 18 8.7 4.8 18000 -6.0 21.2 265 5 2 7.0 3.8 | -4.7 23.5 265 32 16 8.0 4.4 17500 -5.0 23.0 260 4 2 6.9 3.8 | -3.5 25.7 265 29 15 8.1 4.4 17000 -4.0 24.8 255 4 2 7.4 4.1 | -2.4 27.7 270 27 14 7.3 4.0 16500 -2.9 26.8 255 4 2 7.7 4.2 | -1.4 29.5 275 24 12 6.8 3.7 16000 -1.7 28.9 255 4 2 7.9 4.3 | -0.4 31.3 280 21 11 6.8 3.7 15500 -0.5 31.1 250 4 2 8.8 4.8 | 0.6 33.1 290 19 10 7.0 3.8 15000 0.8 33.4 250 5 2 8.8 4.8 | 1.6 34.9 300 18 9 6.9 3.8 14500 2.2 36.0 245 5 3 9.0 4.9 | 2.7 36.9 310 16 8 7.5 4.1 14000 3.5 38.3 245 6 3 8.9 4.9 | 3.8 38.8 320 15 7 7.4 4.1 13500 4.9 40.8 245 6 3 9.1 5.0 | 4.9 40.8 330 13 7 7.8 4.3 13000 6.2 43.2 245 6 3 9.1 5.0 | 6.1 43.0 335 12 6 7.8 4.3 12500 7.6 45.7 245 7 4 9.2 5.0 | 7.2 45.0 345 10 5 7.7 4.2 12000 9.0 48.2 245 8 4 9.2 5.0 | 8.3 46.9 345 9 4 7.6 4.1 11500 10.3 50.5 245 8 4 9.2 5.0 | 9.4 48.9 355 7 4 7.5 4.1 11000 11.7 53.1 245 9 4 9.0 4.9 | 10.5 50.9 360 6 3 7.3 4.0 10500 13.1 55.6 250 9 5 5.4 3.0 | 11.6 52.9 005 5 3 4.3 2.4 10250 13.3 55.9 250 9 5 6.9 3.8 | 11.8 53.2 005 5 3 4.9 2.7 10000 14.2 57.6 250 9 5 12.1 6.6 | 12.5 54.5 015 4 2 9.6 5.3 9750 15.0 59.0 250 10 5 11.0 6.1 | 13.1 55.6 020 4 2 9.1 5.0 9500 15.8 60.4 250 10 5 8.7 4.8 | 13.8 56.8 030 4 2 7.4 4.1 9250 16.3 61.3 250 10 5 6.8 3.7 | 14.2 57.6 030 4 2 5.8 3.2 9000 16.9 62.4 250 11 5 9.9 5.5 | 14.7 58.5 035 4 2 8.4 4.6 8750 17.7 63.9 250 11 6 10.9 6.0 | 15.4 59.7 035 3 2 9.6 5.3 8500 18.5 65.3 250 11 6 8.7 4.8 | 16.0 60.8 040 3 2 8.0 4.4 8250 19.0 66.2 250 11 6 7.2 4.0 | 16.6 61.9 040 3 2 6.8 3.7 8000 19.6 67.3 250 12 6 8.8 4.8 | 17.1 62.8 040 3 2 8.6 4.7 7750 20.3 68.5 250 12 6 9.8 5.4 | 17.8 64.0 045 3 1 10.1 5.5 7500 21.0 69.8 245 12 6 9.0 4.9 | 18.5 65.3 050 2 1 9.0 4.9 7250 21.6 70.9 245 12 6 8.5 4.7 | 19.2 66.6 050 2 1 8.1 4.4 7000 22.3 72.1 245 12 6 9.4 5.1 | 19.8 67.6 050 2 1 10.1 5.5 6750 23.0 73.4 245 12 6 10.4 5.7 | 20.6 69.1 055 2 1 11.3 6.2 6500 23.8 74.8 245 12 6 10.0 5.5 | 21.4 70.5 060 2 1 10.0 5.5 6250 24.5 76.1 245 11 6 10.1 5.5 | 22.1 71.8 060 2 1 10.3 5.7 6000 25.3 77.5 245 11 6 9.3 5.1 | 22.9 73.2 060 2 1 9.0 5.0 5750 26.0 78.8 245 11 6 12.7 7.0 | 23.6 74.5 065 2 1 11.9 6.5 5500 27.3 81.1 245 9 5 20.9 11.5 | 24.8 76.6 080 2 1 20.3 11.1 ________________________________________________________________________________ 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