Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
737 UXUS97 KBOU 201230 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0628 MDT Friday, September 20, 2024 This forecast is for Friday, September 20, 2024: If the trigger temperature of 78.2 F/25.7 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 944 ft/min (4.8 m/s) Maximum height of thermals.................. 16978 ft MSL (11684 ft AGL) Forecast maximum temperature................... 88.0 F/31.6 C Time of trigger temperature.................... 1145 MDT Time of overdevelopment........................ None Middle/high clouds during soaring window....... Overcast thin high Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 12802 ft MSL (7508 ft AGL) Thermal soaring outlook for Saturday 09/21..... Fair 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....................... 40252 ft MSL (34958 ft AGL) Wave soaring outlook for Saturday 09/21........ Poor Remarks... Warm today. Cold front arrives early Saturday morning. Sunrise/Sunset.................... 06:46:04 / 18:59:14 MDT Total possible sunshine........... 12 hr 13 min 10 sec (733 min 10 sec) Altitude of sun at 12:52:39 MDT... 50.87 degrees Upper air data from numerical model forecast valid on 09/20/2024 at 0600 MDT Freezing level.................. 14893 ft MSL (9599 ft AGL) Convective condensation level... 19828 ft MSL (14534 ft AGL) Lifted condensation level....... 18467 ft MSL (13173 ft AGL) Lifted index.................... +2.4 K index......................... +14.7 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 -64.0 -83.2 250 59 30 2.8 1.5 M M M M M 45000 -58.4 -73.1 250 76 39 5.4 3.0 M M M M M 40000 -50.2 -58.4 245 86 44 6.2 3.4 M M M M M 38000 -46.5 -51.7 245 88 45 6.2 3.4 M M M M M 36000 -42.7 -44.9 245 89 46 6.2 3.4 M M M M M 34000 -39.1 -38.4 245 84 43 6.1 3.3 M M M M M 32000 -35.0 -31.0 240 77 40 5.8 3.2 M M M M M 30000 -30.9 -23.6 240 68 35 7.1 3.9 45.1 113.1 10.5 M M 29000 -28.8 -19.8 240 64 33 7.1 3.9 44.1 111.3 9.9 M M 28000 -26.7 -16.1 235 59 30 7.5 4.1 43.2 109.7 9.3 M M 27000 -24.3 -11.7 240 57 29 8.0 4.4 42.4 108.3 8.8 M M 26000 -21.9 -7.4 240 54 28 8.0 4.4 41.7 107.1 8.3 M M 25000 -19.5 -3.1 240 52 27 8.1 4.4 41.2 106.1 8.0 M M 24000 -17.2 1.0 235 48 25 7.4 4.0 40.3 104.6 7.4 M M 23000 -14.9 5.2 235 44 23 7.5 4.1 39.5 103.0 6.8 M M 22000 -12.6 9.3 235 41 21 7.8 4.3 38.7 101.7 6.4 M M 21000 -10.8 12.6 235 37 19 5.5 3.0 37.4 99.3 5.3 M M 20000 -9.2 15.4 235 32 17 5.5 3.0 35.8 96.5 4.0 M M 19500 -8.4 16.9 235 30 15 5.5 3.0 35.1 95.2 3.4 M M 19000 -7.5 18.5 235 28 14 5.5 3.0 34.4 94.0 2.8 M M 18500 -6.7 19.9 240 26 14 5.5 3.0 33.7 92.6 2.2 M M 18000 -5.9 21.4 240 25 13 5.5 3.0 33.0 91.3 1.5 M M 17500 -5.1 22.8 245 23 12 5.4 3.0 32.2 90.0 0.9 M M 17000 -4.3 24.3 250 23 12 5.5 3.0 31.5 88.7 0.2 M M 16500 -3.5 25.7 250 22 11 6.3 3.4 30.8 87.5 -0.5 1016 5.2 16000 -2.1 28.2 255 20 10 7.0 3.8 30.1 86.1 -1.3 952 4.8 15500 -1.2 29.8 255 19 10 7.8 4.3 29.6 85.4 -1.8 908 4.6 15000 -0.0 32.0 255 17 9 8.0 4.4 29.3 84.8 -2.1 858 4.4 14500 1.1 34.0 255 15 8 8.4 4.6 29.1 84.3 -2.4 809 4.1 14000 2.5 36.5 255 14 7 8.9 4.9 28.9 84.0 -2.6 755 3.8 13500 3.8 38.8 250 12 6 8.9 4.9 28.8 83.8 -2.8 701 3.6 13000 5.1 41.2 255 11 5 8.8 4.8 28.6 83.5 -3.0 647 3.3 12500 6.3 43.3 255 9 5 8.7 4.8 28.5 83.2 -3.1 594 3.0 12000 7.5 45.5 260 8 4 7.1 3.9 28.2 82.7 -3.5 545 2.8 11500 8.6 47.5 265 6 3 7.2 3.9 27.8 82.0 -3.9 498 2.5 11000 9.7 49.5 285 5 3 7.7 4.2 27.4 81.3 -4.2 449 2.3 10500 10.8 51.4 300 5 3 6.9 3.8 27.1 80.7 -4.6 400 2.0 10250 11.3 52.3 310 5 3 5.6 3.0 26.8 80.2 -4.9 379 1.9 10000 11.8 53.2 315 6 3 8.1 4.4 26.5 79.7 -5.1 357 1.8 9750 12.5 54.5 320 6 3 9.8 5.4 26.5 79.7 -5.1 329 1.7 9500 13.2 55.8 320 7 4 9.4 5.2 26.5 79.7 -5.2 300 1.5 9250 13.9 57.0 325 8 4 8.1 4.4 26.4 79.6 -5.2 272 1.4 9000 14.4 57.9 325 9 4 7.2 3.9 26.2 79.2 -5.4 249 1.3 8750 15.0 59.0 325 9 5 7.8 4.3 26.1 78.9 -5.6 224 1.1 8500 15.6 60.1 325 10 5 7.5 4.1 25.9 78.6 -5.7 199 1.0 8250 16.1 61.0 325 10 5 6.8 3.7 25.7 78.3 -5.9 175 0.9 8000 16.6 61.9 325 10 5 5.9 3.2 25.5 77.8 -6.2 153 0.8 7750 17.0 62.6 325 10 5 6.1 3.3 25.2 77.3 -6.5 133 0.7 7500 17.4 63.3 325 10 5 4.4 2.4 24.8 76.7 -6.9 113 0.6 7250 17.6 63.7 325 9 5 1.5 0.8 24.3 75.7 -7.4 100 0.5 7000 17.7 63.9 330 9 4 0.5 0.2 23.6 74.5 -8.1 90 0.5 6750 17.8 64.0 330 8 4 1.4 0.7 22.9 73.3 -8.8 82 0.4 6500 17.8 64.0 335 8 4 -3.1 -1.7 22.2 72.0 -9.5 74 0.4 6250 17.3 63.1 330 6 3 -7.2 -4.0 21.0 69.8 -10.8 82 0.4 6000 16.8 62.2 325 5 3 -6.1 -3.3 19.8 67.6 -12.1 89 0.5 5750 16.3 61.3 310 4 2 -5.9 -3.3 18.6 65.4 -13.3 97 0.5 5500 15.8 60.4 265 3 1 -6.1 -3.3 17.4 63.3 -14.6 104 0.5 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 09/20/2024 at 0900 MDT | 09/20/2024 at 1200 MDT | CAPE... 0.0 LI... +3.3 | CAPE... 0.0 LI... +2.8 CINH... 0.0 K Index... +19.3 | CINH... 0.0 K Index... +20.2 | 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 -63.7 -82.7 255 58 30 1.8 1.0 | -62.6 -80.7 250 50 26 0.9 0.5 45000 -59.1 -74.4 245 79 41 5.8 3.2 | -59.2 -74.6 245 82 42 5.4 3.0 40000 -50.3 -58.5 245 87 45 6.1 3.3 | -50.9 -59.6 240 91 47 6.6 3.6 38000 -46.7 -52.1 240 87 45 6.1 3.3 | -46.9 -52.4 240 90 46 6.5 3.6 36000 -43.0 -45.4 240 87 45 6.1 3.3 | -43.0 -45.4 240 89 46 6.5 3.6 34000 -39.4 -38.9 240 81 42 5.9 3.2 | -39.4 -38.9 235 83 42 5.8 3.2 32000 -35.9 -32.6 240 74 38 5.9 3.3 | -35.5 -31.9 235 74 38 5.6 3.1 30000 -31.3 -24.3 235 66 34 7.3 4.0 | -31.3 -24.3 235 67 34 7.6 4.2 29000 -29.2 -20.6 235 63 33 7.3 4.0 | -29.0 -20.2 235 63 33 7.6 4.2 28000 -27.0 -16.6 235 60 31 7.7 4.2 | -26.8 -16.2 235 60 31 7.5 4.1 27000 -24.6 -12.3 235 58 30 8.2 4.5 | -24.6 -12.3 235 58 30 7.0 3.9 26000 -22.1 -7.8 235 57 29 8.2 4.5 | -22.5 -8.5 235 56 29 7.0 3.9 25000 -19.7 -3.5 235 55 28 8.3 4.6 | -20.4 -4.7 235 54 28 7.0 3.9 24000 -17.4 0.7 235 52 27 7.2 3.9 | -18.2 -0.8 235 52 27 7.2 4.0 23000 -15.2 4.6 235 48 25 7.2 4.0 | -16.0 3.2 235 50 26 7.3 4.0 22000 -13.0 8.6 235 44 23 7.5 4.1 | -13.7 7.3 235 47 24 7.6 4.1 21000 -11.2 11.8 230 40 21 5.5 3.0 | -11.8 10.8 235 44 23 6.0 3.3 20000 -9.5 14.9 230 35 18 5.5 3.0 | -10.0 14.0 235 41 21 6.0 3.3 19500 -8.7 16.3 230 33 17 5.5 3.0 | -9.1 15.6 235 39 20 6.0 3.3 19000 -7.8 18.0 230 31 16 5.7 3.1 | -8.2 17.2 235 38 19 6.3 3.4 18500 -7.0 19.4 230 29 15 5.9 3.2 | -7.2 19.0 235 35 18 6.5 3.6 18000 -6.1 21.0 230 27 14 6.0 3.3 | -6.2 20.8 235 33 17 6.7 3.7 17500 -5.4 22.3 235 26 13 4.6 2.5 | -5.4 22.3 235 31 16 4.7 2.6 17000 -4.7 23.5 235 25 13 5.0 2.8 | -4.4 24.1 230 27 14 5.1 2.8 16500 -4.0 24.8 235 24 12 5.7 3.1 | -3.7 25.3 230 24 13 5.2 2.9 16000 -2.9 26.8 240 21 11 6.2 3.4 | -3.0 26.6 230 22 11 5.7 3.1 15500 -2.0 28.4 240 19 10 8.0 4.4 | -2.3 27.9 225 20 10 7.8 4.3 15000 -0.8 30.6 240 17 9 8.4 4.6 | -1.1 30.0 225 19 10 8.4 4.6 14500 0.4 32.7 235 15 8 8.7 4.8 | 0.0 32.0 220 17 9 8.9 4.9 14000 1.8 35.2 235 13 7 9.0 4.9 | 1.5 34.7 220 17 9 9.3 5.1 13500 3.1 37.6 235 11 6 8.9 4.9 | 2.9 37.2 215 16 8 9.3 5.1 13000 4.5 40.1 235 9 5 8.6 4.7 | 4.3 39.7 215 15 8 9.0 4.9 12500 5.8 42.4 235 7 4 8.5 4.7 | 5.6 42.1 210 13 7 9.0 4.9 12000 7.0 44.6 230 6 3 7.9 4.3 | 6.9 44.4 205 12 6 8.0 4.4 11500 8.2 46.8 230 4 2 8.0 4.4 | 8.1 46.6 195 10 5 8.1 4.4 11000 9.4 48.9 230 2 1 8.1 4.4 | 9.3 48.7 185 9 5 8.0 4.4 10500 10.6 51.1 245 1 1 6.3 3.5 | 10.6 51.1 175 8 4 6.9 3.8 10250 11.0 51.8 255 1 1 6.1 3.4 | 11.0 51.8 165 7 4 5.2 2.9 10000 11.6 52.9 290 2 1 9.9 5.5 | 11.4 52.5 170 6 3 7.6 4.2 9750 12.4 54.3 305 2 1 10.5 5.8 | 12.1 53.8 170 5 3 9.0 4.9 9500 13.2 55.8 315 3 2 10.3 5.6 | 12.8 55.0 170 4 2 8.7 4.8 9250 13.9 57.0 320 4 2 7.6 4.1 | 13.4 56.1 170 3 2 8.0 4.4 9000 14.4 57.9 320 5 3 6.9 3.8 | 13.9 57.0 175 2 1 7.2 3.9 8750 15.0 59.0 325 6 3 8.5 4.7 | 14.5 58.1 170 1 1 7.2 3.9 8500 15.6 60.1 325 7 4 7.7 4.2 | 15.0 59.0 000 0 0 7.2 3.9 8250 16.1 61.0 330 7 4 6.5 3.6 | 15.5 59.9 005 1 0 7.4 4.1 8000 16.5 61.7 330 8 4 5.2 2.9 | 16.1 61.0 020 1 0 7.1 3.9 7750 16.9 62.4 335 8 4 4.5 2.4 | 16.6 61.9 025 1 0 6.4 3.5 7500 17.2 63.0 335 8 4 4.0 2.2 | 17.1 62.8 030 1 1 6.3 3.5 7250 17.5 63.5 340 7 4 3.7 2.0 | 17.5 63.5 030 1 0 6.4 3.5 7000 17.8 64.0 340 7 4 3.4 1.9 | 18.0 64.4 000 0 0 6.1 3.4 6750 18.0 64.4 335 6 3 2.3 1.3 | 18.4 65.1 000 0 0 4.4 2.4 6500 18.1 64.6 330 5 3 -0.8 -0.4 | 18.7 65.7 235 1 0 3.8 2.1 6250 17.9 64.2 315 4 2 -2.6 -1.4 | 19.0 66.2 215 2 1 4.6 2.5 6000 17.7 63.9 285 3 2 -1.8 -1.0 | 19.3 66.7 210 3 1 4.0 2.2 5750 17.5 63.5 250 4 2 -1.7 -1.0 | 19.6 67.3 210 4 2 4.6 2.5 5500 17.3 63.1 225 4 2 -4.1 -2.2 | 20.1 68.2 205 4 2 9.4 5.1 09/20/2024 at 1500 MDT | 09/20/2024 at 1800 MDT | CAPE... 0.0 LI... +2.5 | CAPE... 0.0 LI... +0.2 CINH... 0.0 K Index... +13.0 | CINH... 0.0 K Index... +19.2 | 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 -62.7 -80.9 245 51 26 0.9 0.5 | -63.6 -82.5 245 51 26 1.8 1.0 45000 -59.3 -74.7 245 86 44 5.4 3.0 | -59.3 -74.7 250 83 42 5.3 2.9 40000 -51.1 -60.0 240 94 49 6.6 3.6 | -51.2 -60.2 240 96 49 6.6 3.6 38000 -47.1 -52.8 240 93 48 6.6 3.6 | -47.3 -53.1 240 95 49 6.5 3.6 36000 -43.2 -45.8 235 91 47 6.5 3.6 | -43.4 -46.1 240 94 48 6.5 3.6 34000 -39.3 -38.7 235 85 44 6.4 3.5 | -39.4 -38.9 240 89 46 6.7 3.7 32000 -35.0 -31.0 235 77 40 6.3 3.5 | -34.8 -30.6 235 82 42 6.7 3.7 30000 -31.1 -24.0 235 70 36 6.7 3.7 | -31.2 -24.2 235 74 38 6.0 3.3 29000 -29.1 -20.4 235 67 34 6.7 3.7 | -29.4 -20.9 240 70 36 6.0 3.3 28000 -27.2 -17.0 235 63 33 7.0 3.8 | -27.6 -17.7 240 66 34 6.5 3.6 27000 -24.9 -12.8 235 60 31 7.8 4.3 | -25.3 -13.5 240 63 32 7.8 4.3 26000 -22.6 -8.7 235 57 29 7.8 4.3 | -23.0 -9.4 240 59 30 7.8 4.3 25000 -20.2 -4.4 235 54 28 7.8 4.3 | -20.7 -5.3 240 55 29 7.8 4.3 24000 -18.0 -0.4 235 52 27 7.3 4.0 | -18.4 -1.1 240 53 27 7.6 4.2 23000 -15.7 3.7 235 51 26 7.3 4.0 | -16.1 3.0 240 51 26 7.6 4.2 22000 -13.5 7.7 235 49 25 7.5 4.1 | -13.7 7.3 245 49 25 8.0 4.4 21000 -11.5 11.3 240 47 24 6.1 3.4 | -12.1 10.2 245 43 22 4.6 2.5 20000 -9.7 14.5 240 44 23 6.1 3.4 | -10.8 12.6 250 36 19 4.8 2.6 19500 -8.8 16.2 240 43 22 6.1 3.4 | -10.2 13.6 250 33 17 5.1 2.8 19000 -7.9 17.8 245 42 21 6.2 3.4 | -9.5 14.9 250 29 15 7.0 3.9 18500 -7.0 19.4 245 40 20 6.3 3.5 | -8.3 17.1 250 26 13 8.7 4.8 18000 -6.1 21.0 245 38 20 6.5 3.6 | -7.1 19.2 250 23 12 8.9 4.9 17500 -4.7 23.5 245 34 18 6.5 3.6 | -5.8 21.6 250 21 11 8.8 4.8 17000 -3.8 25.2 245 31 16 6.6 3.6 | -3.9 25.0 245 22 11 8.9 4.9 16500 -2.8 27.0 240 29 15 7.1 3.9 | -2.6 27.3 240 22 11 7.7 4.2 16000 -1.7 28.9 240 27 14 7.1 3.9 | -1.4 29.5 235 24 12 7.9 4.3 15500 -0.7 30.7 235 26 13 7.1 3.9 | -0.1 31.8 235 25 13 8.3 4.6 15000 0.4 32.7 230 26 13 7.1 3.9 | 1.1 34.0 230 25 13 8.5 4.6 14500 1.4 34.5 230 25 13 7.3 4.0 | 2.4 36.3 225 25 13 8.8 4.9 14000 2.5 36.5 225 25 13 7.8 4.3 | 3.8 38.8 225 24 12 9.5 5.2 13500 3.5 38.3 225 24 12 8.1 4.4 | 5.2 41.4 220 24 12 9.5 5.2 13000 4.8 40.6 220 23 12 9.1 5.0 | 6.6 43.9 220 23 12 9.5 5.2 12500 6.1 43.0 215 22 11 9.0 4.9 | 8.1 46.6 215 22 11 9.5 5.2 12000 7.5 45.5 215 20 11 9.5 5.2 | 9.4 48.9 210 21 11 9.1 5.0 11500 8.9 48.0 210 19 10 9.6 5.3 | 10.8 51.4 210 20 10 9.3 5.1 11000 10.2 50.4 210 18 9 7.7 4.2 | 12.0 53.6 205 18 9 7.4 4.0 10500 11.3 52.3 205 16 8 8.3 4.5 | 13.1 55.6 195 17 9 8.4 4.6 10250 12.0 53.6 200 15 8 9.9 5.4 | 13.8 56.8 195 16 8 9.9 5.4 10000 12.7 54.9 195 14 7 8.9 4.9 | 14.4 57.9 190 15 8 8.4 4.6 9750 13.3 55.9 190 13 7 7.4 4.1 | 15.0 59.0 185 14 7 7.6 4.2 9500 13.9 57.0 180 12 6 8.0 4.4 | 15.6 60.1 180 13 7 8.0 4.4 9250 14.5 58.1 175 11 6 7.0 3.8 | 16.1 61.0 175 13 6 7.4 4.1 9000 14.9 58.8 165 10 5 6.0 3.3 | 16.6 61.9 170 11 6 6.9 3.8 8750 15.4 59.7 160 10 5 6.3 3.5 | 17.2 63.0 165 11 5 7.1 3.9 8500 15.9 60.6 150 9 5 5.9 3.3 | 17.7 63.9 160 10 5 6.8 3.7 8250 16.4 61.5 145 8 4 8.0 4.4 | 18.2 64.8 155 9 5 7.8 4.3 8000 17.0 62.6 135 7 4 7.8 4.3 | 18.8 65.8 140 8 4 6.5 3.5 7750 17.5 63.5 130 7 3 5.1 2.8 | 19.2 66.6 130 7 4 4.2 2.3 7500 17.9 64.2 125 6 3 5.6 3.1 | 19.5 67.1 115 7 3 4.6 2.5 7250 18.4 65.1 120 6 3 7.4 4.0 | 19.9 67.8 100 6 3 7.2 3.9 7000 19.0 66.2 120 5 3 8.0 4.4 | 20.5 68.9 095 6 3 8.6 4.7 6750 19.5 67.1 115 5 3 5.5 3.0 | 21.1 70.0 090 6 3 6.4 3.5 6500 19.9 67.8 115 4 2 6.7 3.7 | 21.6 70.9 085 5 3 7.5 4.1 6250 20.5 68.9 120 4 2 9.9 5.4 | 22.3 72.1 080 5 3 10.4 5.7 6000 21.3 70.3 130 3 1 9.8 5.4 | 23.1 73.6 080 5 2 11.2 6.2 5750 22.0 71.6 140 2 1 10.0 5.5 | 23.9 75.0 075 4 2 9.5 5.2 5500 22.8 73.0 145 2 1 14.1 7.8 | 24.5 76.1 070 4 2 7.3 4.0 ________________________________________________________________________________ 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