Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
177 UXUS97 KBOU 070021 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1821 MDT Thursday, June 6, 2024 This forecast is for Friday, June 7, 2024: If the trigger temperature of 87.1 F/30.6 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1148 ft/min (5.8 m/s) Maximum height of thermals.................. 17362 ft MSL (12072 ft AGL) Forecast maximum temperature................... 93.0 F/34.3 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................. 9487 ft MSL (4197 ft AGL) Thermal soaring outlook for Saturday 06/08..... 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....................... 40771 ft MSL (35481 ft AGL) Wave soaring outlook for Saturday 06/08........ Fair Remarks... None Sunrise/Sunset.................... 05:31:21 / 20:25:41 MDT Total possible sunshine........... 14 hr 54 min 20 sec (894 min 20 sec) Altitude of sun at 12:58:31 MDT... 73.08 degrees Upper air data from numerical model forecast valid on 06/07/2024 at 0600 MDT Freezing level.................. 16516 ft MSL (11226 ft AGL) Convective condensation level... 16915 ft MSL (11625 ft AGL) Lifted condensation level....... 17076 ft MSL (11786 ft AGL) Lifted index.................... -3.3 K index......................... +18.6 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 -62.6 -80.7 260 28 14 -0.1 -0.1 M M M M M 45000 -61.1 -78.0 260 36 19 3.9 2.1 M M M M M 40000 -54.7 -66.5 260 44 23 7.4 4.0 M M M M M 38000 -50.2 -58.4 260 44 23 7.4 4.1 M M M M M 36000 -45.8 -50.4 255 43 22 7.4 4.0 M M M M M 34000 -41.0 -41.8 260 41 21 8.1 4.4 M M M M M 32000 -35.6 -32.1 265 39 20 8.2 4.5 M M M M M 30000 -30.6 -23.1 265 37 19 8.3 4.5 44.7 112.5 8.3 M M 29000 -28.1 -18.6 265 36 19 8.3 4.5 44.2 111.6 8.0 M M 28000 -25.7 -14.3 265 35 18 7.6 4.2 43.7 110.7 7.7 M M 27000 -23.4 -10.1 265 33 17 7.4 4.1 42.7 108.9 7.0 M M 26000 -21.2 -6.2 270 31 16 7.5 4.1 41.9 107.3 6.3 M M 25000 -19.0 -2.2 270 29 15 7.4 4.1 41.1 106.0 5.8 M M 24000 -17.1 1.2 270 27 14 6.2 3.4 39.8 103.6 4.7 M M 23000 -15.3 4.5 275 25 13 6.2 3.4 38.5 101.3 3.7 M M 22000 -13.5 7.7 280 24 12 6.5 3.6 37.3 99.2 2.7 M M 21000 -11.3 11.7 285 24 12 7.4 4.1 36.4 97.5 1.8 M M 20000 -9.1 15.6 290 24 12 7.4 4.1 35.5 96.0 1.1 M M 19500 -8.1 17.4 295 24 13 7.3 4.0 35.2 95.3 0.8 M M 19000 -6.9 19.6 295 24 13 9.0 4.9 34.9 94.8 0.5 M M 18500 -5.5 22.1 295 24 12 9.0 4.9 34.8 94.6 0.4 M M 18000 -4.2 24.4 295 23 12 8.9 4.9 34.6 94.3 0.3 M M 17500 -2.9 26.8 295 22 11 8.6 4.7 34.4 94.0 0.1 M M 17000 -1.6 29.1 290 22 11 8.6 4.7 34.3 93.7 -0.1 1122 5.7 16500 0.4 32.7 290 21 11 9.3 5.1 34.1 93.3 -0.3 1040 5.3 16000 1.7 35.1 290 21 11 9.4 5.1 34.0 93.2 -0.4 984 5.0 15500 3.1 37.6 285 21 11 8.5 4.7 33.8 92.9 -0.5 930 4.7 15000 4.3 39.7 285 21 11 8.6 4.7 33.7 92.6 -0.7 877 4.5 14500 5.6 42.1 285 21 11 9.2 5.0 33.5 92.3 -0.9 824 4.2 14000 7.0 44.6 280 21 11 9.3 5.1 33.4 92.2 -1.0 767 3.9 13500 8.4 47.1 280 20 10 9.2 5.1 33.4 92.1 -1.1 711 3.6 13000 9.7 49.5 280 20 10 9.1 5.0 33.3 91.9 -1.2 656 3.3 12500 11.1 52.0 280 19 10 8.9 4.9 33.2 91.7 -1.3 600 3.0 12000 12.3 54.1 280 18 9 8.5 4.7 33.0 91.3 -1.5 548 2.8 11500 13.6 56.5 285 17 9 8.5 4.6 32.8 91.0 -1.8 496 2.5 11000 14.8 58.6 285 15 8 8.1 4.4 32.5 90.6 -2.0 445 2.3 10500 16.0 60.8 290 14 7 4.6 2.5 32.3 90.2 -2.3 395 2.0 10250 16.2 61.2 290 14 7 5.4 2.9 31.8 89.2 -2.8 382 1.9 10000 16.9 62.4 290 13 7 10.8 5.9 31.8 89.2 -2.9 354 1.8 9750 17.5 63.5 290 12 6 9.5 5.2 31.8 89.2 -3.0 326 1.7 9500 18.2 64.8 290 12 6 9.3 5.1 31.8 89.2 -3.0 298 1.5 9250 18.8 65.8 290 11 6 6.3 3.5 31.6 88.9 -3.2 273 1.4 9000 19.2 66.6 290 11 6 6.3 3.4 31.3 88.4 -3.5 253 1.3 8750 19.7 67.5 290 11 6 7.8 4.3 31.1 88.0 -3.7 230 1.2 8500 20.2 68.4 290 11 5 7.2 4.0 30.9 87.7 -3.9 208 1.1 8250 20.7 69.3 285 10 5 7.0 3.8 30.7 87.3 -4.2 185 0.9 8000 21.2 70.2 275 10 5 6.0 3.3 30.5 86.9 -4.5 164 0.8 7750 21.6 70.9 270 10 5 5.4 2.9 30.2 86.3 -4.8 145 0.7 7500 22.0 71.6 260 10 5 4.7 2.6 29.8 85.7 -5.2 126 0.6 7250 22.3 72.1 255 10 5 3.8 2.1 29.4 84.9 -5.6 110 0.6 7000 22.5 72.5 250 10 5 2.8 1.5 28.9 84.1 -6.1 95 0.5 6750 22.7 72.9 245 10 5 4.0 2.2 28.4 83.1 -6.7 82 0.4 6500 22.8 73.0 240 10 5 -5.6 -3.1 27.8 82.0 -7.3 71 0.4 6250 21.8 71.2 235 11 6 -14.7 -8.0 26.1 78.9 -9.1 94 0.5 6000 20.8 69.4 225 12 6 -11.9 -6.5 24.4 75.9 -10.8 117 0.6 5750 19.7 67.5 215 13 6 -15.2 -8.4 22.7 72.8 -12.6 141 0.7 5500 18.3 64.9 205 12 6 -19.8 -10.8 20.6 69.0 -14.8 177 0.9 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 06/07/2024 at 0900 MDT | 06/07/2024 at 1200 MDT | CAPE... +118.1 LI... +0.3 | CAPE... +354.2 LI... -0.2 CINH... -143.0 K Index... +18.8 | CINH... -26.9 K Index... +22.0 | 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 -61.9 -79.4 260 25 13 -0.2 -0.1 | -61.6 -78.9 255 22 11 1.1 0.6 45000 -60.5 -76.9 260 31 16 3.8 2.1 | -59.2 -74.6 255 29 15 2.7 1.5 40000 -54.4 -65.9 260 40 21 6.9 3.8 | -54.6 -66.3 265 42 22 6.9 3.8 38000 -50.3 -58.5 255 41 21 6.8 3.8 | -50.6 -59.1 265 43 22 6.8 3.7 36000 -46.2 -51.2 255 41 21 6.8 3.7 | -46.5 -51.7 260 43 22 6.8 3.7 34000 -40.9 -41.6 255 40 21 8.1 4.4 | -41.1 -42.0 255 43 22 8.2 4.5 32000 -36.1 -33.0 255 38 20 8.0 4.4 | -36.2 -33.2 255 43 22 8.2 4.5 30000 -31.3 -24.3 260 37 19 8.0 4.4 | -31.9 -25.4 255 38 19 7.1 3.9 29000 -28.9 -20.0 260 37 19 8.0 4.4 | -29.8 -21.6 255 35 18 7.1 3.9 28000 -26.5 -15.7 260 36 18 7.2 4.0 | -27.7 -17.9 260 32 16 7.0 3.8 27000 -24.5 -12.1 260 34 18 6.9 3.8 | -25.6 -14.1 260 31 16 7.0 3.8 26000 -22.4 -8.3 265 33 17 6.9 3.8 | -23.5 -10.3 265 30 15 7.0 3.8 25000 -20.4 -4.7 265 31 16 6.9 3.8 | -21.5 -6.7 270 29 15 7.1 3.9 24000 -18.4 -1.1 270 30 16 6.8 3.7 | -19.2 -2.6 270 30 15 8.0 4.4 23000 -16.4 2.5 275 29 15 6.8 3.7 | -16.8 1.8 275 30 16 8.0 4.4 22000 -14.4 6.1 275 28 15 7.0 3.9 | -14.4 6.1 275 31 16 8.1 4.5 21000 -12.1 10.2 280 27 14 8.0 4.4 | -11.9 10.6 280 31 16 8.5 4.7 20000 -9.7 14.5 285 27 14 8.0 4.4 | -9.4 15.1 280 31 16 8.6 4.7 19500 -8.6 16.5 290 26 14 8.0 4.4 | -8.1 17.4 285 31 16 8.6 4.7 19000 -7.4 18.7 290 26 13 8.5 4.6 | -6.9 19.6 285 31 16 8.7 4.8 18500 -6.1 21.0 295 26 13 8.5 4.7 | -5.6 21.9 285 31 16 8.7 4.8 18000 -4.2 24.4 295 25 13 8.6 4.7 | -3.7 25.3 285 30 16 8.5 4.7 17500 -3.0 26.6 295 25 13 8.7 4.8 | -2.4 27.7 285 30 15 8.5 4.7 17000 -1.7 28.9 295 24 13 8.7 4.8 | -1.2 29.8 285 29 15 8.5 4.7 16500 -0.4 31.3 295 24 12 8.8 4.8 | 0.1 32.2 285 28 15 8.5 4.7 16000 0.9 33.6 295 23 12 8.8 4.8 | 1.3 34.3 285 27 14 8.5 4.7 15500 2.2 36.0 295 23 12 9.2 5.1 | 2.5 36.5 285 27 14 8.3 4.6 15000 3.6 38.5 295 22 12 9.2 5.0 | 3.8 38.8 285 26 13 8.3 4.6 14500 4.9 40.8 295 22 11 9.2 5.0 | 5.1 41.2 285 26 13 8.9 4.9 14000 6.3 43.3 295 22 11 9.2 5.0 | 6.4 43.5 285 25 13 9.0 4.9 13500 7.7 45.9 295 21 11 9.2 5.1 | 7.7 45.9 285 24 12 9.3 5.1 13000 9.1 48.4 295 21 11 9.3 5.1 | 9.1 48.4 285 24 12 9.5 5.2 12500 10.5 50.9 295 21 11 9.3 5.1 | 10.5 50.9 290 23 12 9.4 5.2 12000 11.9 53.4 295 21 11 9.2 5.0 | 11.8 53.2 290 22 11 9.2 5.0 11500 13.3 55.9 295 21 11 9.0 5.0 | 13.2 55.8 290 21 11 8.9 4.9 11000 14.5 58.1 295 21 11 7.7 4.2 | 14.3 57.7 290 20 10 7.6 4.2 10500 15.6 60.1 290 21 11 11.2 6.1 | 15.4 59.7 290 19 10 12.3 6.8 10250 16.6 61.9 290 20 10 12.0 6.6 | 16.6 61.9 290 17 9 13.6 7.5 10000 17.3 63.1 290 20 10 7.8 4.3 | 17.3 63.1 290 17 9 8.1 4.4 9750 17.9 64.2 290 20 10 9.0 5.0 | 18.0 64.4 295 16 8 9.8 5.4 9500 18.6 65.5 290 20 10 8.4 4.6 | 18.6 65.5 295 15 8 8.4 4.6 9250 19.2 66.6 290 20 10 7.6 4.2 | 19.2 66.6 295 15 8 8.0 4.4 9000 19.7 67.5 290 20 10 8.0 4.4 | 19.9 67.8 295 14 7 9.7 5.3 8750 20.3 68.5 290 19 10 8.7 4.8 | 20.7 69.3 295 14 7 10.4 5.7 8500 21.0 69.8 290 19 10 8.3 4.5 | 21.4 70.5 295 13 7 10.0 5.5 8250 21.6 70.9 290 19 10 7.4 4.1 | 22.1 71.8 300 13 7 9.1 5.0 8000 22.1 71.8 290 18 9 6.8 3.8 | 22.8 73.0 300 13 7 9.7 5.3 7750 22.6 72.7 290 18 9 7.3 4.0 | 23.6 74.5 300 13 7 10.9 6.0 7500 23.1 73.6 290 17 9 5.9 3.3 | 24.4 75.9 300 12 6 9.8 5.4 7250 23.4 74.1 290 16 8 3.2 1.7 | 25.0 77.0 300 12 6 7.9 4.3 7000 23.6 74.5 290 15 8 3.5 1.9 | 25.6 78.1 300 12 6 8.9 4.9 6750 23.9 75.0 295 14 7 6.9 3.8 | 26.4 79.5 300 12 6 12.9 7.1 6500 24.4 75.9 295 12 6 6.1 3.3 | 27.4 81.3 300 11 6 12.0 6.6 6250 24.6 76.3 290 9 5 4.0 2.2 | 28.2 82.8 300 11 6 10.0 5.5 6000 24.9 76.8 290 7 4 4.0 2.2 | 29.0 84.2 300 11 6 9.9 5.4 5750 25.2 77.4 280 5 3 7.1 3.9 | 29.8 85.6 300 11 6 12.4 6.8 5500 26.0 78.8 270 4 2 17.3 9.5 | 31.0 87.8 300 10 5 23.8 13.1 06/07/2024 at 1500 MDT | 06/07/2024 at 1800 MDT | CAPE... +503.3 LI... -1.6 | CAPE... +491.4 LI... -1.2 CINH... -6.4 K Index... +28.8 | CINH... -56.6 K Index... +19.0 | 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 -62.3 -80.1 250 24 12 -0.2 -0.1 | -62.2 -80.0 260 26 13 -0.5 -0.3 45000 -60.7 -77.3 250 32 16 4.1 2.2 | -60.8 -77.4 250 32 17 4.4 2.4 40000 -54.3 -65.7 260 44 23 6.6 3.6 | -53.9 -65.0 250 38 19 7.0 3.8 38000 -50.3 -58.5 260 43 22 6.7 3.7 | -49.8 -57.6 250 38 19 6.9 3.8 36000 -46.3 -51.3 260 42 22 6.5 3.6 | -45.6 -50.1 250 38 19 6.9 3.8 34000 -41.3 -42.3 260 44 23 8.6 4.7 | -40.1 -40.2 255 40 21 8.3 4.6 32000 -35.5 -31.9 255 47 24 8.9 4.9 | -35.1 -31.2 265 44 23 8.5 4.6 30000 -31.0 -23.8 255 45 23 7.6 4.2 | -30.9 -23.6 265 43 22 6.8 3.7 29000 -28.7 -19.7 255 44 23 7.6 4.2 | -28.9 -20.0 265 42 22 6.8 3.7 28000 -26.4 -15.5 255 44 22 7.5 4.1 | -26.9 -16.4 265 42 21 7.9 4.3 27000 -24.2 -11.6 260 42 22 7.5 4.1 | -24.4 -11.9 260 39 20 8.5 4.7 26000 -22.0 -7.6 265 41 21 7.6 4.1 | -21.8 -7.2 260 36 18 8.6 4.7 25000 -19.8 -3.6 265 40 21 7.5 4.1 | -19.3 -2.7 260 33 17 8.6 4.7 24000 -17.7 0.1 270 39 20 7.0 3.9 | -17.1 1.2 260 30 16 7.1 3.9 23000 -15.6 3.9 270 38 20 7.1 3.9 | -15.0 5.0 260 28 15 7.1 3.9 22000 -13.5 7.7 275 37 19 7.3 4.0 | -12.9 8.8 265 26 13 7.2 3.9 21000 -11.2 11.8 275 36 18 7.9 4.4 | -10.7 12.7 265 24 13 7.6 4.2 20000 -8.9 16.0 275 35 18 8.0 4.4 | -8.4 16.9 270 23 12 7.6 4.2 19500 -7.7 18.1 275 34 18 8.0 4.4 | -7.3 18.9 275 22 11 7.6 4.2 19000 -6.6 20.1 275 33 17 8.2 4.5 | -6.2 20.8 275 21 11 8.0 4.4 18500 -5.4 22.3 275 32 17 8.2 4.5 | -5.0 23.0 280 21 11 8.1 4.4 18000 -4.2 24.4 275 32 16 8.4 4.6 | -3.8 25.2 280 21 11 8.2 4.5 17500 -2.9 26.8 275 30 16 8.7 4.8 | -1.8 28.8 280 20 10 8.6 4.7 17000 -1.7 28.9 275 29 15 8.7 4.8 | -0.6 30.9 280 20 10 8.7 4.8 16500 -0.4 31.3 270 28 15 9.6 5.2 | 0.7 33.3 280 19 10 9.0 4.9 16000 1.0 33.8 270 27 14 9.5 5.2 | 2.1 35.8 280 19 10 9.0 5.0 15500 3.1 37.6 270 26 13 9.0 4.9 | 3.4 38.1 280 18 9 8.5 4.6 15000 4.5 40.1 275 24 13 9.0 5.0 | 4.6 40.3 280 18 9 8.5 4.7 14500 5.9 42.6 275 23 12 9.2 5.1 | 5.9 42.6 280 18 9 8.7 4.8 14000 7.2 45.0 275 21 11 9.3 5.1 | 7.2 45.0 280 19 10 8.8 4.8 13500 8.6 47.5 275 20 10 9.1 5.0 | 8.5 47.3 280 19 10 8.9 4.9 13000 10.0 50.0 280 16 8 9.0 4.9 | 9.8 49.6 280 19 10 9.2 5.0 12500 11.3 52.3 280 13 7 9.1 5.0 | 11.2 52.2 285 19 10 9.1 5.0 12000 12.7 54.9 280 11 6 9.4 5.2 | 12.5 54.5 285 20 10 8.6 4.7 11500 14.1 57.4 285 9 5 9.3 5.1 | 13.8 56.8 285 21 11 8.7 4.8 11000 15.4 59.7 285 9 4 8.8 4.8 | 14.9 58.8 285 22 11 7.4 4.1 10500 16.7 62.1 285 8 4 11.5 6.3 | 16.0 60.8 285 22 11 10.1 5.5 10250 17.7 63.9 285 8 4 12.1 6.7 | 16.9 62.4 290 23 12 10.8 5.9 10000 18.4 65.1 290 8 4 8.9 4.9 | 17.5 63.5 285 23 12 7.8 4.3 9750 19.1 66.4 290 8 4 9.9 5.4 | 18.1 64.6 285 23 12 8.6 4.7 9500 19.8 67.6 290 8 4 9.3 5.1 | 18.7 65.7 285 23 12 8.3 4.6 9250 20.5 68.9 290 8 4 9.4 5.2 | 19.3 66.7 285 23 12 8.0 4.4 9000 21.3 70.3 290 8 4 10.2 5.6 | 19.9 67.8 285 24 12 8.2 4.5 8750 22.0 71.6 290 8 4 10.4 5.7 | 20.5 68.9 285 25 13 8.6 4.7 8500 22.8 73.0 290 8 4 10.4 5.7 | 21.1 70.0 285 25 13 8.5 4.6 8250 23.6 74.5 290 8 4 11.1 6.1 | 21.7 71.1 285 25 13 9.2 5.0 8000 24.4 75.9 290 7 4 10.4 5.7 | 22.4 72.3 285 25 13 9.1 5.0 7750 25.1 77.2 290 7 4 9.4 5.1 | 23.0 73.4 285 24 13 8.5 4.7 7500 25.9 78.6 290 7 4 9.8 5.4 | 23.6 74.5 285 24 12 8.9 4.9 7250 26.6 79.9 290 7 4 10.1 5.5 | 24.3 75.7 290 23 12 10.1 5.5 7000 27.4 81.3 290 7 4 10.3 5.7 | 25.1 77.2 290 22 11 10.2 5.6 6750 28.1 82.6 290 7 4 10.7 5.8 | 25.8 78.4 290 20 10 8.9 4.9 6500 28.9 84.0 290 7 4 10.6 5.8 | 26.4 79.5 290 19 10 9.4 5.2 6250 29.7 85.5 295 7 4 10.6 5.8 | 27.2 81.0 290 17 9 10.7 5.8 6000 30.5 86.9 295 7 3 10.3 5.6 | 28.0 82.4 290 16 8 10.8 5.9 5750 31.3 88.3 295 7 3 11.2 6.2 | 28.7 83.7 290 15 7 9.4 5.2 5500 32.4 90.3 295 6 3 19.3 10.6 | 29.4 84.9 290 13 7 11.3 6.2 ________________________________________________________________________________ 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