Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
791 UXUS97 KBOU 250058 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1857 MDT Monday, June 24, 2024 This forecast is for Tuesday, June 25, 2024: If the trigger temperature of 86.2 F/30.1 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1531 ft/min (7.8 m/s) Maximum height of thermals.................. 21295 ft MSL (16005 ft AGL) Forecast maximum temperature................... 98.0 F/37.1 C Time of trigger temperature.................... 0930 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................. 18396 ft MSL (13106 ft AGL) Thermal soaring outlook for Wednesday 06/26.... 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....................... 17827 ft MSL (12537 ft AGL) Wave soaring outlook for Wednesday 06/26....... Fair Remarks... None Sunrise/Sunset.................... 05:33:00 / 20:31:39 MDT Total possible sunshine........... 14 hr 58 min 39 sec (898 min 39 sec) Altitude of sun at 13:02:19 MDT... 73.58 degrees Upper air data from numerical model forecast valid on 06/25/2024 at 0600 MDT Freezing level.................. 16006 ft MSL (10716 ft AGL) Convective condensation level... 18958 ft MSL (13668 ft AGL) Lifted condensation level....... 20155 ft MSL (14865 ft AGL) Lifted index.................... -1.5 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 -63.8 -82.8 295 47 24 3.8 2.1 M M M M M 45000 -56.7 -70.1 290 64 33 6.5 3.6 M M M M M 40000 -46.7 -52.1 290 68 35 5.5 3.0 M M M M M 38000 -43.4 -46.1 290 66 34 5.5 3.0 M M M M M 36000 -40.1 -40.2 290 64 33 5.5 3.0 M M M M M 34000 -37.0 -34.6 290 56 29 5.0 2.8 M M M M M 32000 -34.0 -29.2 295 48 25 4.9 2.7 M M M M M 30000 -30.0 -22.0 295 43 22 7.2 3.9 46.3 115.4 7.3 M M 29000 -27.3 -17.1 295 41 21 7.2 3.9 45.1 113.2 6.5 M M 28000 -25.1 -13.2 295 38 20 7.0 3.9 44.2 111.6 5.9 M M 27000 -23.0 -9.4 300 35 18 7.1 3.9 43.1 109.6 5.1 M M 26000 -20.9 -5.6 300 31 16 7.1 3.9 42.1 107.7 4.3 M M 25000 -18.8 -1.8 300 28 14 6.8 3.8 41.2 106.2 3.7 M M 24000 -16.8 1.8 300 23 12 6.5 3.6 39.9 103.8 2.6 M M 23000 -14.9 5.2 295 19 10 6.6 3.6 38.7 101.7 1.7 M M 22000 -13.0 8.6 290 14 7 6.6 3.6 37.7 99.9 0.8 M M 21000 -11.0 12.2 295 14 7 6.6 3.6 36.5 97.7 -0.3 1507 7.7 20000 -9.1 15.6 295 14 7 6.7 3.7 35.4 95.8 -1.3 1419 7.2 19500 -8.1 17.4 295 14 7 6.7 3.7 34.9 94.9 -1.7 1375 7.0 19000 -7.2 19.0 295 14 7 6.5 3.6 34.4 93.9 -2.2 1333 6.8 18500 -6.3 20.7 295 13 7 6.7 3.7 33.8 92.9 -2.8 1290 6.6 18000 -5.4 22.3 295 13 7 7.7 4.2 33.3 92.0 -3.4 1248 6.3 17500 -4.1 24.6 300 12 6 8.5 4.7 33.1 91.6 -3.6 1196 6.1 17000 -2.9 26.8 300 12 6 8.6 4.7 32.9 91.3 -3.9 1145 5.8 16500 -1.6 29.1 305 11 6 9.3 5.1 32.8 91.0 -4.1 1091 5.5 16000 -0.3 31.5 310 11 5 9.3 5.1 32.7 90.9 -4.2 1037 5.3 15500 1.1 34.0 315 10 5 9.0 5.0 32.6 90.7 -4.4 982 5.0 15000 3.0 37.4 320 10 5 9.0 4.9 32.4 90.4 -4.6 900 4.6 14500 4.4 39.9 325 10 5 9.1 5.0 32.3 90.2 -4.8 845 4.3 14000 5.7 42.3 330 10 5 9.1 5.0 32.2 90.0 -4.9 790 4.0 13500 7.1 44.8 335 9 5 9.2 5.1 32.1 89.8 -5.0 735 3.7 13000 8.5 47.3 335 9 5 9.2 5.1 32.0 89.7 -5.1 679 3.4 12500 9.8 49.6 340 10 5 9.0 5.0 32.0 89.5 -5.2 622 3.2 12000 11.2 52.2 345 9 5 8.8 4.9 31.8 89.3 -5.4 567 2.9 11500 12.5 54.5 345 9 5 8.7 4.8 31.7 89.0 -5.5 513 2.6 11000 13.8 56.8 350 10 5 8.4 4.6 31.5 88.7 -5.7 458 2.3 10500 15.2 59.4 350 10 5 4.9 2.7 31.3 88.4 -5.8 404 2.1 10250 15.4 59.7 350 10 5 6.1 3.4 30.8 87.5 -6.3 389 2.0 10000 16.2 61.2 355 10 5 11.7 6.4 30.9 87.6 -6.3 358 1.8 9750 17.0 62.6 355 10 5 10.7 5.9 30.9 87.7 -6.2 327 1.7 9500 17.8 64.0 355 10 5 9.2 5.0 31.0 87.8 -6.2 296 1.5 9250 18.3 64.9 355 10 5 7.0 3.8 30.8 87.5 -6.4 272 1.4 9000 18.9 66.0 355 9 5 8.2 4.5 30.7 87.2 -6.6 248 1.3 8750 19.5 67.1 355 9 5 8.7 4.8 30.6 87.1 -6.6 221 1.1 8500 20.2 68.4 355 9 5 8.5 4.7 30.5 86.9 -6.7 193 1.0 8250 20.8 69.4 355 9 5 8.5 4.7 30.4 86.7 -6.8 167 0.8 8000 21.5 70.7 350 9 4 8.3 4.5 30.3 86.6 -7.0 141 0.7 7750 22.1 71.8 350 9 5 7.8 4.3 30.2 86.3 -7.1 116 0.6 7500 22.7 72.9 345 9 5 8.6 4.7 30.0 86.1 -7.2 90 0.5 7250 23.3 73.9 340 10 5 8.9 4.9 30.0 86.0 -7.3 63 0.3 7000 24.0 75.2 335 10 5 9.8 5.4 29.9 85.9 -7.4 35 0.2 6750 24.7 76.5 330 11 6 7.6 4.2 29.9 85.9 -7.4 7 0.0 6500 24.9 76.8 325 12 6 -3.0 -1.6 29.4 84.9 -8.0 M M 6250 24.2 75.6 310 11 6 -9.5 -5.2 28.1 82.6 -9.4 6 0.0 6000 23.6 74.5 300 11 6 -3.9 -2.1 26.8 80.2 -10.8 18 0.1 5750 23.1 73.6 290 13 6 -12.1 -6.7 25.7 78.3 -12.0 24 0.1 5500 21.1 70.0 270 9 4 -40.0 -21.9 23.0 73.4 -14.8 77 0.4 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 06/25/2024 at 0900 MDT | 06/25/2024 at 1200 MDT | CAPE... +29.6 LI... -0.0 | CAPE... +66.7 LI... -0.2 CINH... -59.4 K Index... +19.6 | CINH... -7.8 K Index... +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 -62.9 -81.2 295 43 22 3.0 1.7 | -62.7 -80.9 295 39 20 3.2 1.8 45000 -56.2 -69.2 290 58 30 6.2 3.4 | -56.0 -68.8 295 55 29 5.9 3.3 40000 -47.0 -52.6 290 61 31 5.9 3.2 | -47.1 -52.8 290 62 32 5.8 3.2 38000 -43.5 -46.3 290 60 31 5.9 3.2 | -43.7 -46.7 290 62 32 5.8 3.2 36000 -40.0 -40.0 295 60 31 5.8 3.2 | -40.2 -40.4 295 62 32 5.7 3.1 34000 -37.0 -34.6 295 52 27 4.9 2.7 | -36.9 -34.4 295 54 28 5.4 2.9 32000 -34.1 -29.4 300 43 22 4.8 2.6 | -33.3 -27.9 295 44 23 5.8 3.2 30000 -29.6 -21.3 300 39 20 7.0 3.8 | -29.3 -20.7 295 40 21 6.7 3.7 29000 -27.5 -17.5 300 37 19 7.0 3.8 | -27.3 -17.1 295 38 19 6.7 3.7 28000 -25.4 -13.7 300 35 18 6.9 3.8 | -25.3 -13.5 295 36 18 7.0 3.9 27000 -23.3 -9.9 300 33 17 6.9 3.8 | -23.2 -9.8 295 34 17 7.0 3.8 26000 -21.3 -6.3 300 30 15 6.9 3.8 | -21.1 -6.0 295 31 16 7.0 3.8 25000 -19.2 -2.6 295 27 14 6.5 3.6 | -19.0 -2.2 295 29 15 6.7 3.7 24000 -17.4 0.7 295 23 12 5.9 3.2 | -17.1 1.2 290 26 13 6.4 3.5 23000 -15.7 3.7 295 20 10 6.0 3.3 | -15.2 4.6 290 22 12 6.4 3.5 22000 -13.9 7.0 290 16 8 6.5 3.6 | -13.3 8.1 280 19 10 6.6 3.6 21000 -11.9 10.6 295 16 8 7.0 3.9 | -11.3 11.7 290 18 9 6.6 3.6 20000 -9.8 14.4 295 16 8 7.1 3.9 | -9.3 15.3 295 16 8 6.7 3.7 19500 -8.8 16.2 300 16 8 7.1 3.9 | -8.4 16.9 300 16 8 6.8 3.7 19000 -7.7 18.1 300 16 8 7.8 4.3 | -7.2 19.0 305 16 8 8.3 4.6 18500 -6.6 20.1 300 16 8 7.8 4.3 | -6.0 21.2 310 17 9 8.2 4.5 18000 -5.4 22.3 300 15 8 8.3 4.5 | -4.8 23.4 315 17 9 8.3 4.6 17500 -4.2 24.4 305 15 8 8.6 4.7 | -2.9 26.8 320 18 9 8.4 4.6 17000 -2.3 27.9 305 15 8 9.1 5.0 | -1.7 28.9 320 19 10 8.7 4.8 16500 -0.9 30.4 305 15 8 9.4 5.1 | -0.4 31.3 325 19 10 8.8 4.8 16000 0.5 32.9 305 15 8 9.4 5.2 | 0.9 33.6 325 19 10 8.9 4.9 15500 1.8 35.2 305 15 8 9.2 5.1 | 2.2 36.0 325 19 10 9.0 5.0 15000 3.1 37.6 305 14 7 9.2 5.1 | 3.6 38.5 325 19 10 9.0 4.9 14500 4.5 40.1 310 14 7 9.4 5.2 | 4.9 40.8 325 18 9 9.4 5.1 14000 5.9 42.6 310 14 7 9.4 5.2 | 6.3 43.3 325 17 9 9.3 5.1 13500 7.3 45.1 310 13 7 9.3 5.1 | 7.7 45.9 325 17 9 9.3 5.1 13000 8.6 47.5 310 13 6 9.2 5.1 | 9.0 48.2 325 16 8 9.3 5.1 12500 10.0 50.0 310 12 6 9.1 5.0 | 10.4 50.7 325 15 8 9.4 5.2 12000 11.3 52.3 315 11 6 9.0 4.9 | 11.8 53.2 320 14 7 9.5 5.2 11500 12.7 54.9 315 11 5 9.2 4.9 | 13.1 55.6 320 12 6 9.4 5.2 11000 14.0 57.2 320 10 5 8.6 4.7 | 14.5 58.1 320 10 5 9.0 4.9 10500 15.3 59.5 325 10 5 3.9 2.2 | 15.8 60.4 325 9 4 4.4 2.4 10250 15.4 59.7 325 9 5 5.3 2.9 | 16.0 60.8 325 9 4 6.3 3.5 10000 16.3 61.3 330 9 5 12.5 6.8 | 16.9 62.4 325 8 4 13.7 7.5 9750 17.1 62.8 330 9 5 11.3 6.2 | 17.8 64.0 325 7 4 12.7 6.9 9500 17.9 64.2 335 9 5 8.9 4.9 | 18.7 65.7 325 7 4 9.5 5.2 9250 18.4 65.1 340 9 5 6.5 3.6 | 19.2 66.6 330 7 3 7.5 4.1 9000 19.0 66.2 345 9 5 9.2 5.1 | 19.9 67.8 330 6 3 11.1 6.1 8750 19.7 67.5 345 9 5 10.4 5.7 | 20.8 69.4 330 6 3 11.7 6.4 8500 20.5 68.9 345 9 5 8.7 4.8 | 21.6 70.9 330 6 3 10.1 5.5 8250 21.0 69.8 350 9 4 7.1 3.9 | 22.3 72.1 335 6 3 8.2 4.5 8000 21.6 70.9 360 8 4 7.7 4.2 | 22.9 73.2 335 5 3 10.2 5.6 7750 22.2 72.0 360 8 4 8.1 4.5 | 23.8 74.8 335 5 3 11.5 6.3 7500 22.8 73.0 355 8 4 7.1 3.9 | 24.6 76.3 335 5 3 9.4 5.2 7250 23.2 73.8 360 8 4 6.0 3.3 | 25.2 77.4 335 5 3 7.8 4.3 7000 23.7 74.7 005 7 4 7.3 4.0 | 25.8 78.4 340 5 3 9.8 5.4 6750 24.3 75.7 005 7 4 9.1 5.0 | 26.7 80.1 340 5 2 12.5 6.9 6500 24.9 76.8 360 6 3 7.3 4.0 | 27.6 81.7 340 5 2 11.4 6.2 6250 25.3 77.5 360 6 3 6.2 3.4 | 28.4 83.1 340 4 2 10.9 6.0 6000 25.8 78.4 360 5 2 5.2 2.8 | 29.2 84.6 345 4 2 9.1 5.0 5750 26.1 79.0 355 4 2 9.2 5.0 | 29.9 85.8 340 4 2 15.5 8.5 5500 27.2 81.0 350 3 2 21.0 11.5 | 31.7 89.1 345 4 2 33.0 18.1 06/25/2024 at 1500 MDT | 06/25/2024 at 1800 MDT | CAPE... +0.3 LI... +0.8 | CAPE... 0.0 LI... +1.2 CINH... -0.7 K Index... +16.9 | CINH... -0.3 K Index... +19.6 | 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 -62.8 -81.0 290 38 19 3.7 2.1 | -62.7 -80.9 295 28 14 4.1 2.3 45000 -56.1 -69.0 295 52 27 5.7 3.1 | -55.6 -68.1 300 43 22 5.6 3.1 40000 -47.3 -53.1 295 64 33 6.5 3.6 | -47.0 -52.6 300 58 30 6.5 3.5 38000 -43.5 -46.3 295 64 33 6.5 3.5 | -43.1 -45.6 300 62 32 6.5 3.5 36000 -39.6 -39.3 295 65 34 6.2 3.4 | -39.2 -38.6 295 66 34 6.2 3.4 34000 -35.9 -32.6 295 56 29 5.4 3.0 | -35.4 -31.7 295 61 32 5.7 3.1 32000 -32.6 -26.7 295 47 24 5.6 3.1 | -32.0 -25.6 295 57 29 6.0 3.3 30000 -29.1 -20.4 290 44 22 5.9 3.2 | -28.4 -19.1 290 51 26 6.0 3.3 29000 -27.3 -17.1 290 42 22 5.8 3.2 | -26.6 -15.9 290 48 25 6.0 3.3 28000 -25.4 -13.7 285 41 21 8.1 4.4 | -24.8 -12.6 290 45 23 5.9 3.2 27000 -23.1 -9.6 285 42 21 7.9 4.3 | -23.0 -9.4 285 44 22 6.0 3.3 26000 -20.8 -5.4 285 42 22 8.0 4.4 | -21.3 -6.3 285 42 22 6.0 3.3 25000 -18.4 -1.1 285 42 22 7.6 4.2 | -19.5 -3.1 280 40 21 6.4 3.5 24000 -16.2 2.8 285 36 18 7.2 4.0 | -17.5 0.5 275 37 19 6.6 3.6 23000 -14.0 6.8 280 29 15 7.3 4.0 | -15.5 4.1 275 35 18 6.6 3.6 22000 -11.8 10.8 275 23 12 6.0 3.3 | -13.5 7.7 270 32 16 7.9 4.3 21000 -10.3 13.5 285 23 12 5.1 2.8 | -10.9 12.4 275 28 14 8.7 4.8 20000 -8.8 16.2 295 23 12 5.5 3.0 | -8.4 16.9 280 24 13 8.7 4.8 19500 -8.1 17.4 300 23 12 6.0 3.3 | -7.1 19.2 280 23 12 8.6 4.7 19000 -7.0 19.4 300 22 11 9.1 5.0 | -5.9 21.4 280 20 11 7.5 4.1 18500 -5.8 21.6 305 21 11 9.1 5.0 | -4.8 23.4 280 18 9 7.6 4.1 18000 -4.6 23.7 305 21 11 9.0 4.9 | -3.7 25.3 280 16 8 8.8 4.8 17500 -2.5 27.5 305 19 10 8.9 4.9 | -2.3 27.9 275 14 7 9.3 5.1 17000 -1.2 29.8 305 18 9 9.3 5.1 | -0.3 31.5 270 10 5 9.3 5.1 16500 0.2 32.4 310 17 9 9.5 5.2 | 1.0 33.8 265 8 4 9.3 5.1 16000 1.7 35.1 310 16 8 9.3 5.1 | 2.4 36.3 255 6 3 9.3 5.1 15500 3.0 37.4 315 14 7 8.7 4.8 | 3.7 38.7 245 5 3 9.2 5.0 15000 4.3 39.7 315 12 6 8.7 4.8 | 5.1 41.2 235 4 2 9.2 5.1 14500 5.7 42.3 320 10 5 9.0 5.0 | 6.4 43.5 220 4 2 9.2 5.0 14000 7.0 44.6 325 9 5 9.0 5.0 | 7.8 46.0 215 3 2 9.2 5.0 13500 8.4 47.1 330 8 4 8.6 4.7 | 9.2 48.6 200 2 1 8.9 4.9 13000 9.6 49.3 335 7 3 8.5 4.7 | 10.5 50.9 190 2 1 8.9 4.9 12500 10.9 51.6 345 6 3 8.8 4.8 | 11.8 53.2 170 1 1 9.1 5.0 12000 12.2 54.0 345 5 2 9.0 4.9 | 13.2 55.8 145 1 0 9.2 5.0 11500 13.6 56.5 350 4 2 9.2 5.0 | 14.6 58.3 095 1 0 9.1 5.0 11000 15.0 59.0 350 4 2 9.0 5.0 | 16.0 60.8 055 1 0 8.9 4.9 10500 16.4 61.5 350 4 2 5.0 2.8 | 17.4 63.3 030 1 1 5.2 2.8 10250 16.6 61.9 350 4 2 6.4 3.5 | 17.6 63.7 030 1 1 6.8 3.8 10000 17.5 63.5 350 4 2 12.8 7.0 | 18.5 65.3 020 1 1 12.8 7.0 9750 18.3 64.9 350 3 2 11.6 6.4 | 19.4 66.9 010 1 1 11.9 6.5 9500 19.2 66.6 345 3 2 10.0 5.5 | 20.2 68.4 005 2 1 9.5 5.2 9250 19.8 67.6 345 3 2 8.7 4.8 | 20.8 69.4 005 2 1 7.8 4.3 9000 20.6 69.1 345 3 2 10.7 5.9 | 21.5 70.7 360 2 1 10.4 5.7 8750 21.4 70.5 345 3 2 11.1 6.1 | 22.3 72.1 355 2 1 10.7 5.9 8500 22.2 72.0 340 3 2 10.4 5.7 | 23.1 73.6 355 2 1 10.3 5.7 8250 23.0 73.4 340 3 2 9.9 5.4 | 23.8 74.8 350 2 1 10.1 5.5 8000 23.7 74.7 340 3 2 9.8 5.4 | 24.6 76.3 350 2 1 9.8 5.4 7750 24.4 75.9 335 3 2 9.6 5.3 | 25.3 77.5 345 2 1 9.5 5.2 7500 25.2 77.4 335 3 2 10.2 5.6 | 26.0 78.8 345 2 1 9.6 5.3 7250 25.9 78.6 335 3 2 10.6 5.8 | 26.7 80.1 340 2 1 9.6 5.2 7000 26.7 80.1 330 3 2 10.3 5.7 | 27.5 81.5 340 2 1 9.9 5.4 6750 27.5 81.5 330 3 2 10.3 5.7 | 28.2 82.8 335 2 1 10.4 5.7 6500 28.3 82.9 330 3 2 10.6 5.8 | 29.0 84.2 335 2 1 10.1 5.5 6250 29.1 84.4 325 3 2 11.5 6.3 | 29.7 85.5 335 3 1 10.1 5.5 6000 29.9 85.8 325 3 2 8.8 4.8 | 30.5 86.9 330 3 1 9.4 5.2 5750 30.6 87.1 325 3 2 14.5 8.0 | 31.2 88.2 330 3 1 11.1 6.1 5500 32.4 90.3 325 3 2 32.6 17.9 | 32.3 90.1 330 3 1 16.4 9.0 ________________________________________________________________________________ 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