Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
020 UXUS97 KBOU 070119 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1918 MDT Sunday, July 6, 2025 This forecast is for Monday, July 7, 2025: If the trigger temperature of 82.0 F/27.8 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1593 ft/min (8.1 m/s) Maximum height of thermals.................. 21772 ft MSL (16425 ft AGL) Forecast maximum temperature................... 93.0 F/34.3 C Time of trigger temperature.................... 1045 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................. 12844 ft MSL (7497 ft AGL) Thermal soaring outlook for Tuesday 07/08...... 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)................ Weak PVA Potential height of wave....................... 40952 ft MSL (35605 ft AGL) Wave soaring outlook for Tuesday 07/08......... Fair Remarks... Sunrise/Sunset.................... 05:38:53 / 20:30:10 MDT Total possible sunshine........... 14 hr 51 min 16 sec (891 min 16 sec) Altitude of sun at 13:04:32 MDT... 72.70 degrees Upper air data from numerical model forecast valid on 07/07/2025 at 0600 MDT Freezing level.................. 15781 ft MSL (10434 ft AGL) Convective condensation level... 14198 ft MSL (8851 ft AGL) Lifted condensation level....... 15474 ft MSL (10127 ft AGL) Lifted index.................... -9.5 K index......................... +20.0 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 -61.4 -78.5 255 35 18 1.4 0.8 M M M M M 45000 -56.9 -70.4 260 58 30 5.9 3.2 M M M M M 40000 -48.4 -55.1 270 63 33 4.4 2.4 M M M M M 38000 -45.8 -50.4 270 58 30 4.3 2.4 M M M M M 36000 -43.2 -45.8 265 54 28 4.3 2.3 M M M M M 34000 -40.0 -40.0 270 48 25 5.5 3.0 M M M M M 32000 -36.7 -34.1 270 43 22 5.5 3.0 M M M M M 30000 -33.4 -28.1 270 36 19 4.8 2.7 41.8 107.2 6.0 M M 29000 -31.9 -25.4 270 33 17 4.9 2.7 39.9 103.8 4.6 M M 28000 -30.5 -22.9 270 30 16 7.0 3.9 38.3 100.9 3.4 M M 27000 -28.0 -18.4 275 30 15 8.3 4.5 37.6 99.6 2.9 M M 26000 -25.5 -13.9 275 29 15 8.3 4.5 37.0 98.6 2.4 M M 25000 -23.1 -9.6 280 29 15 8.2 4.5 36.6 97.8 2.1 M M 24000 -20.8 -5.4 285 29 15 7.6 4.2 35.7 96.3 1.4 M M 23000 -18.5 -1.3 290 29 15 7.6 4.2 34.9 94.8 0.7 M M 22000 -16.3 2.7 290 28 15 7.8 4.3 34.2 93.6 0.2 M M 21000 -13.8 7.2 295 27 14 8.2 4.5 33.6 92.4 -0.4 1519 7.7 20000 -11.4 11.5 295 26 13 8.2 4.5 33.0 91.4 -0.9 1417 7.2 19500 -10.2 13.6 300 25 13 8.1 4.4 32.8 91.0 -1.1 1365 6.9 19000 -8.9 16.0 300 25 13 8.9 4.9 32.6 90.7 -1.3 1313 6.7 18500 -7.6 18.3 295 24 12 8.9 4.9 32.4 90.4 -1.5 1259 6.4 18000 -6.3 20.7 295 23 12 8.9 4.9 32.3 90.1 -1.6 1205 6.1 17500 -4.3 24.3 295 21 11 9.0 4.9 32.1 89.8 -1.8 1124 5.7 17000 -3.0 26.6 290 20 10 9.1 5.0 32.0 89.6 -2.0 1069 5.4 16500 -1.7 28.9 290 19 10 9.1 5.0 31.9 89.3 -2.1 1014 5.2 16000 -0.3 31.5 290 18 9 9.2 5.0 31.8 89.2 -2.2 959 4.9 15500 1.0 33.8 285 16 8 9.3 5.1 31.7 89.0 -2.4 904 4.6 15000 2.4 36.3 285 15 8 9.3 5.1 31.6 88.9 -2.5 849 4.3 14500 3.7 38.7 285 14 7 9.4 5.1 31.5 88.7 -2.6 793 4.0 14000 5.1 41.2 285 13 7 9.4 5.1 31.5 88.6 -2.7 737 3.7 13500 6.5 43.7 285 12 6 9.0 5.0 31.4 88.5 -2.8 681 3.5 13000 7.8 46.0 285 11 6 8.9 4.9 31.2 88.2 -3.0 627 3.2 12500 9.1 48.4 285 11 5 8.6 4.7 31.1 88.0 -3.1 574 2.9 12000 10.3 50.5 285 10 5 8.4 4.6 30.9 87.6 -3.4 523 2.7 11500 11.5 52.7 280 9 5 8.0 4.4 30.7 87.2 -3.7 472 2.4 11000 12.5 54.5 270 8 4 7.1 3.9 30.3 86.5 -4.1 427 2.2 10500 13.5 56.3 260 8 4 4.7 2.6 29.9 85.9 -4.6 382 1.9 10250 13.7 56.7 260 7 4 5.1 2.8 29.4 84.9 -5.2 369 1.9 10000 14.2 57.6 255 7 4 9.1 5.0 29.3 84.7 -5.4 345 1.8 9750 14.8 58.6 250 6 3 8.9 4.9 29.2 84.6 -5.5 320 1.6 9500 15.4 59.7 245 6 3 7.9 4.3 29.1 84.4 -5.7 295 1.5 9250 15.9 60.6 240 5 3 6.0 3.3 28.9 84.0 -6.0 274 1.4 9000 16.2 61.2 235 5 2 5.5 3.0 28.6 83.4 -6.4 256 1.3 8750 16.5 61.7 235 4 2 5.6 3.1 28.2 82.8 -6.8 239 1.2 8500 16.9 62.4 235 3 2 4.7 2.6 27.9 82.2 -7.2 221 1.1 8250 17.1 62.8 245 3 1 3.8 2.1 27.5 81.4 -7.7 208 1.1 8000 17.3 63.1 265 2 1 2.8 1.6 27.0 80.6 -8.3 194 1.0 7750 17.4 63.3 295 2 1 1.7 0.9 26.4 79.5 -8.9 184 0.9 7500 17.4 63.3 320 2 1 -2.7 -1.5 25.7 78.2 -9.7 177 0.9 7250 16.9 62.4 335 3 2 -6.1 -3.3 24.5 76.1 -10.9 184 0.9 7000 16.5 61.7 345 5 2 -5.4 -2.9 23.4 74.1 -12.1 190 1.0 6750 16.0 60.8 350 6 3 -6.0 -3.3 22.2 71.9 -13.3 197 1.0 6500 15.5 59.9 350 6 3 -4.8 -2.6 21.0 69.8 -14.5 203 1.0 6250 15.2 59.4 350 5 3 -3.8 -2.1 20.0 67.9 -15.6 205 1.0 6000 14.9 58.8 345 4 2 -4.5 -2.5 18.9 66.1 -16.7 208 1.1 5750 14.6 58.3 330 3 2 -0.8 -0.5 17.9 64.3 -17.8 209 1.1 5500 14.8 58.6 330 2 1 6.4 3.5 17.4 63.4 -18.3 195 1.0 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 07/07/2025 at 0900 MDT | 07/07/2025 at 1200 MDT | CAPE... +469.0 LI... -2.5 | CAPE... +927.4 LI... -3.7 CINH... -409.4 K Index... +10.6 | CINH... -85.6 K Index... +12.4 | 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 -62.4 -80.3 260 33 17 2.0 1.1 | -62.3 -80.1 260 32 16 2.3 1.3 45000 -57.0 -70.6 265 56 29 6.3 3.4 | -57.1 -70.8 265 51 26 5.4 2.9 40000 -48.0 -54.4 265 62 32 4.5 2.5 | -49.1 -56.4 270 64 33 5.0 2.7 38000 -45.3 -49.5 270 58 30 4.4 2.4 | -46.1 -51.0 270 59 30 4.9 2.7 36000 -42.7 -44.9 270 54 28 4.4 2.4 | -43.2 -45.8 270 54 28 5.0 2.7 34000 -39.6 -39.3 270 47 24 5.3 2.9 | -40.4 -40.7 275 46 23 4.6 2.5 32000 -36.0 -32.8 275 37 19 5.4 2.9 | -37.6 -35.7 275 36 19 4.7 2.6 30000 -33.3 -27.9 275 31 16 4.4 2.4 | -33.3 -27.9 280 31 16 7.0 3.8 29000 -32.0 -25.6 275 29 15 4.5 2.5 | -31.2 -24.2 285 29 15 7.0 3.8 28000 -30.6 -23.1 275 26 13 6.7 3.7 | -29.2 -20.6 285 28 14 5.8 3.2 27000 -28.2 -18.8 280 26 13 8.0 4.4 | -27.6 -17.7 285 27 14 5.5 3.0 26000 -25.9 -14.6 285 26 13 8.0 4.4 | -25.9 -14.6 280 26 13 5.5 3.0 25000 -23.5 -10.3 285 26 14 7.9 4.3 | -24.3 -11.7 275 25 13 6.3 3.5 24000 -21.3 -6.3 285 26 13 7.3 4.0 | -21.8 -7.2 275 25 13 8.8 4.8 23000 -19.1 -2.4 285 26 13 7.3 4.0 | -19.2 -2.6 275 25 13 8.8 4.8 22000 -16.9 1.6 285 26 13 7.9 4.3 | -16.6 2.1 275 25 13 8.8 4.8 21000 -14.3 6.3 290 25 13 9.1 5.0 | -14.0 6.8 275 23 12 8.8 4.9 20000 -11.6 11.1 290 24 12 9.1 5.0 | -11.4 11.5 275 21 11 8.9 4.9 19500 -10.2 13.6 290 23 12 9.1 5.0 | -10.2 13.6 275 20 10 9.0 4.9 19000 -8.9 16.0 290 23 12 9.1 5.0 | -8.8 16.2 275 20 10 9.0 4.9 18500 -7.5 18.5 290 22 12 9.1 5.0 | -7.4 18.7 275 19 10 9.0 4.9 18000 -5.5 22.1 295 22 11 9.1 5.0 | -6.1 21.0 280 19 10 8.9 4.9 17500 -4.2 24.4 295 21 11 9.1 5.0 | -4.8 23.4 280 18 9 8.8 4.8 17000 -2.8 27.0 295 21 11 9.1 5.0 | -3.4 25.9 280 18 9 8.8 4.8 16500 -1.5 29.3 295 20 10 9.2 5.0 | -1.3 29.7 285 17 9 9.6 5.3 16000 -0.1 31.8 295 19 10 9.2 5.0 | 0.1 32.2 285 17 9 9.5 5.2 15500 1.3 34.3 295 19 10 9.2 5.0 | 1.4 34.5 285 16 8 8.8 4.8 15000 2.6 36.7 295 18 9 9.2 5.0 | 2.8 37.0 285 16 8 8.8 4.8 14500 4.0 39.2 295 17 9 9.1 5.0 | 4.1 39.4 285 15 8 9.4 5.1 14000 5.3 41.5 295 17 9 9.1 5.0 | 5.5 41.9 290 15 8 9.3 5.1 13500 6.7 44.1 290 16 8 9.1 5.0 | 6.9 44.4 290 15 8 9.3 5.1 13000 8.0 46.4 295 15 8 9.0 5.0 | 8.3 46.9 290 14 7 9.3 5.1 12500 9.4 48.9 295 14 7 8.9 4.9 | 9.7 49.5 295 14 7 9.1 5.0 12000 10.6 51.1 295 13 7 8.8 4.8 | 11.0 51.8 295 13 7 9.0 5.0 11500 11.9 53.4 295 12 6 8.4 4.6 | 12.3 54.1 300 12 6 8.8 4.8 11000 13.1 55.6 295 11 6 7.6 4.1 | 13.6 56.5 300 11 6 8.4 4.6 10500 14.2 57.6 295 10 5 4.4 2.4 | 14.9 58.8 300 10 5 5.2 2.9 10250 14.4 57.9 295 9 5 4.0 2.2 | 15.1 59.2 305 10 5 5.9 3.2 10000 14.9 58.8 295 9 4 8.3 4.6 | 15.8 60.4 305 9 5 10.4 5.7 9750 15.4 59.7 290 8 4 8.1 4.4 | 16.5 61.7 305 9 5 9.7 5.3 9500 15.9 60.6 290 8 4 6.7 3.7 | 17.2 63.0 305 8 4 7.8 4.3 9250 16.2 61.2 290 7 4 4.4 2.4 | 17.7 63.9 305 8 4 5.8 3.2 9000 16.5 61.7 285 7 3 4.6 2.5 | 18.2 64.8 305 7 4 7.4 4.1 8750 16.8 62.2 285 6 3 5.4 3.0 | 18.7 65.7 305 7 4 8.0 4.4 8500 17.1 62.8 280 6 3 3.7 2.0 | 19.3 66.7 305 6 3 6.7 3.7 8250 17.1 62.8 280 5 3 2.2 1.2 | 19.7 67.5 305 6 3 5.9 3.2 8000 17.2 63.0 285 5 3 1.8 1.0 | 20.1 68.2 300 5 3 5.7 3.1 7750 17.1 62.8 285 5 2 0.5 0.3 | 20.5 68.9 300 5 2 5.1 2.8 7500 17.0 62.6 285 4 2 -2.0 -1.1 | 20.8 69.4 300 4 2 5.0 2.8 7250 16.7 62.1 290 5 2 -3.4 -1.9 | 21.0 69.8 300 3 2 5.4 3.0 7000 16.4 61.5 295 5 3 -3.5 -1.9 | 21.2 70.2 310 2 1 5.1 2.8 6750 16.1 61.0 300 5 3 -2.1 -1.2 | 21.4 70.5 335 1 1 7.2 4.0 6500 16.1 61.0 295 6 3 2.1 1.2 | 22.0 71.6 345 1 1 10.7 5.8 6250 16.3 61.3 295 5 3 2.9 1.6 | 22.8 73.0 350 1 1 12.0 6.6 6000 16.5 61.7 290 5 3 4.5 2.5 | 23.7 74.7 350 1 1 9.1 5.0 5750 17.1 62.8 285 5 3 13.9 7.6 | 24.4 75.9 350 1 1 15.5 8.5 5500 18.5 65.3 285 5 2 22.9 12.5 | 26.2 79.2 355 1 1 33.6 18.4 07/07/2025 at 1500 MDT | 07/07/2025 at 1800 MDT | CAPE... +457.5 LI... -1.3 | CAPE... +332.3 LI... -1.0 CINH... -26.5 K Index... +21.4 | CINH... -35.3 K Index... +25.3 | 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 -61.2 -78.2 265 33 17 2.7 1.5 | -61.2 -78.2 275 32 16 3.0 1.6 45000 -56.1 -69.0 270 54 28 4.4 2.4 | -55.9 -68.6 275 47 24 4.5 2.5 40000 -49.4 -56.9 270 67 34 4.9 2.7 | -49.0 -56.2 280 57 29 5.3 2.9 38000 -46.5 -51.7 270 62 32 4.9 2.7 | -45.9 -50.6 275 56 29 5.3 2.9 36000 -43.6 -46.5 275 58 30 4.9 2.7 | -42.7 -44.9 275 55 28 5.4 2.9 34000 -40.9 -41.6 270 49 25 4.4 2.4 | -39.8 -39.6 275 48 25 4.1 2.2 32000 -37.9 -36.2 270 38 20 4.0 2.2 | -37.3 -35.1 270 41 21 3.8 2.1 30000 -33.6 -28.5 270 34 18 7.6 4.2 | -33.1 -27.6 270 38 19 7.5 4.1 29000 -31.3 -24.3 270 33 17 7.6 4.2 | -30.9 -23.6 270 36 19 7.5 4.1 28000 -29.1 -20.4 270 31 16 6.8 3.8 | -28.7 -19.7 270 35 18 7.5 4.1 27000 -27.1 -16.8 270 32 16 6.7 3.7 | -26.4 -15.5 270 34 17 7.6 4.1 26000 -25.1 -13.2 270 32 17 6.7 3.7 | -24.2 -11.6 270 32 17 7.6 4.1 25000 -23.1 -9.6 270 33 17 7.1 3.9 | -21.9 -7.4 270 31 16 7.5 4.1 24000 -20.7 -5.3 275 33 17 8.2 4.5 | -19.8 -3.6 270 31 16 7.2 4.0 23000 -18.3 -0.9 275 34 17 8.2 4.5 | -17.6 0.3 275 30 16 7.2 4.0 22000 -15.8 3.6 275 34 18 8.5 4.6 | -15.5 4.1 280 30 16 7.9 4.3 21000 -13.3 8.1 280 31 16 8.7 4.8 | -12.9 8.8 285 29 15 8.6 4.7 20000 -10.7 12.7 280 28 15 8.8 4.8 | -10.4 13.3 290 28 14 8.6 4.7 19500 -9.5 14.9 285 27 14 8.8 4.8 | -9.1 15.6 295 27 14 8.7 4.8 19000 -8.2 17.2 285 25 13 8.6 4.7 | -7.8 18.0 295 26 13 8.9 4.9 18500 -6.9 19.6 285 23 12 8.7 4.8 | -6.5 20.3 300 23 12 9.0 4.9 18000 -5.6 21.9 290 22 11 9.0 4.9 | -5.2 22.6 300 21 11 8.9 4.9 17500 -4.3 24.3 290 20 10 9.2 5.0 | -4.0 24.8 305 18 9 8.8 4.8 17000 -2.3 27.9 290 18 9 8.9 4.9 | -2.1 28.2 305 14 7 8.4 4.6 16500 -1.0 30.2 290 16 8 8.8 4.8 | -0.9 30.4 310 11 5 8.2 4.5 16000 0.3 32.5 290 14 7 8.8 4.8 | 0.3 32.5 315 7 4 8.1 4.5 15500 1.6 34.9 285 13 7 8.6 4.7 | 1.5 34.7 330 5 3 8.0 4.4 15000 2.9 37.2 285 11 6 8.6 4.7 | 2.7 36.9 350 3 2 7.9 4.4 14500 4.2 39.6 280 10 5 8.8 4.9 | 3.9 39.0 020 3 1 9.0 4.9 14000 5.5 41.9 275 8 4 8.8 4.9 | 5.2 41.4 035 3 1 8.9 4.9 13500 6.8 44.2 270 7 4 8.5 4.7 | 6.5 43.7 050 3 1 9.0 5.0 13000 8.1 46.6 265 6 3 8.4 4.6 | 7.9 46.2 050 3 1 9.0 5.0 12500 9.4 48.9 255 5 2 8.9 4.9 | 9.2 48.6 050 3 2 9.4 5.2 12000 10.8 51.4 245 3 1 9.2 5.0 | 10.6 51.1 045 3 2 9.6 5.3 11500 12.1 53.8 205 1 1 9.1 5.0 | 12.1 53.8 045 3 1 9.6 5.3 11000 13.4 56.1 125 1 0 8.7 4.8 | 13.5 56.3 040 3 1 9.4 5.1 10500 14.7 58.5 085 2 1 5.6 3.1 | 14.9 58.8 040 3 1 5.1 2.8 10250 14.9 58.8 085 2 1 6.9 3.8 | 15.2 59.4 035 3 1 6.6 3.6 10000 15.7 60.3 085 2 1 12.1 6.6 | 16.0 60.8 035 3 1 13.1 7.2 9750 16.5 61.7 080 2 1 11.1 6.1 | 16.9 62.4 035 3 1 11.9 6.5 9500 17.3 63.1 080 2 1 9.9 5.4 | 17.8 64.0 030 3 1 9.7 5.3 9250 17.9 64.2 075 2 1 8.9 4.9 | 18.4 65.1 030 3 1 8.1 4.5 9000 18.7 65.7 075 2 1 10.7 5.9 | 19.1 66.4 030 3 1 10.8 5.9 8750 19.5 67.1 075 2 1 11.1 6.1 | 19.9 67.8 025 3 1 11.3 6.2 8500 20.3 68.5 075 2 1 10.4 5.7 | 20.7 69.3 025 3 1 10.3 5.7 8250 21.0 69.8 070 2 1 10.0 5.5 | 21.5 70.7 020 3 1 9.7 5.3 8000 21.8 71.2 070 2 1 9.9 5.5 | 22.2 72.0 020 3 1 9.9 5.4 7750 22.5 72.5 070 2 1 9.8 5.4 | 23.0 73.4 020 3 1 10.0 5.5 7500 23.3 73.9 070 2 1 10.1 5.5 | 23.7 74.7 015 3 1 10.2 5.6 7250 24.0 75.2 065 2 1 10.3 5.6 | 24.5 76.1 015 3 1 10.6 5.8 7000 24.8 76.6 065 2 1 10.0 5.5 | 25.3 77.5 010 3 1 9.7 5.3 6750 25.5 77.9 065 2 1 10.2 5.6 | 26.0 78.8 010 3 1 9.2 5.1 6500 26.3 79.3 060 2 1 10.7 5.8 | 26.7 80.1 010 3 1 10.2 5.6 6250 27.1 80.8 060 2 1 11.7 6.4 | 27.5 81.5 005 3 1 11.0 6.0 6000 28.0 82.4 060 2 1 8.5 4.6 | 28.3 82.9 005 3 1 9.4 5.2 5750 28.6 83.5 055 2 1 14.8 8.1 | 29.0 84.2 360 3 1 12.8 7.0 5500 30.5 86.9 060 2 1 34.6 19.0 | 30.3 86.5 360 3 1 22.7 12.5 ________________________________________________________________________________ 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