![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
887 UXUS97 KBOU 071326 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0724 MDT Saturday, September 7, 2024 This forecast is for Saturday, September 7, 2024: If the trigger temperature of 79.5 F/26.4 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1089 ft/min (5.5 m/s) Maximum height of thermals.................. 17098 ft MSL (11771 ft AGL) Forecast maximum temperature................... 87.0 F/31.0 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................. 10683 ft MSL (5356 ft AGL) Thermal soaring outlook for Sunday 09/08....... 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....................... 40718 ft MSL (35391 ft AGL) Wave soaring outlook for Sunday 09/08.......... Poor Remarks... Sunrise/Sunset.................... 06:33:57 / 19:20:33 MDT Total possible sunshine........... 12 hr 46 min 36 sec (766 min 36 sec) Altitude of sun at 12:57:15 MDT... 55.89 degrees Upper air data from numerical model forecast valid on 09/07/2024 at 0600 MDT Freezing level.................. 15152 ft MSL (9825 ft AGL) Convective condensation level... 16852 ft MSL (11525 ft AGL) Lifted condensation level....... 17069 ft MSL (11742 ft AGL) Lifted index.................... -1.5 K index......................... +19.8 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 -61.2 -78.2 305 28 14 1.1 0.6 M M M M M 45000 -59.2 -74.6 295 33 17 1.8 1.0 M M M M M 40000 -55.9 -68.6 295 41 21 7.1 3.9 M M M M M 38000 -51.8 -61.2 295 39 20 6.8 3.7 M M M M M 36000 -47.8 -54.0 300 36 19 6.8 3.7 M M M M M 34000 -43.9 -47.0 300 32 17 6.3 3.5 M M M M M 32000 -40.1 -40.2 300 29 15 6.4 3.5 M M M M M 30000 -34.9 -30.8 300 27 14 8.2 4.5 39.9 103.8 7.1 M M 29000 -32.5 -26.5 300 26 13 8.2 4.5 39.3 102.8 6.7 M M 28000 -30.0 -22.0 300 25 13 8.5 4.7 38.9 102.0 6.5 M M 27000 -27.4 -17.3 305 25 13 8.6 4.7 38.3 101.0 6.1 M M 26000 -24.9 -12.8 305 25 13 8.6 4.7 37.9 100.2 5.8 M M 25000 -22.3 -8.1 305 25 13 8.5 4.7 37.6 99.6 5.6 M M 24000 -19.8 -3.6 310 25 13 8.3 4.5 37.0 98.5 5.2 M M 23000 -17.3 0.9 310 24 13 8.3 4.5 36.4 97.6 4.8 M M 22000 -14.8 5.4 310 24 13 7.9 4.3 36.0 96.8 4.5 M M 21000 -12.7 9.1 305 24 12 7.2 3.9 35.0 95.0 3.7 M M 20000 -10.5 13.1 305 23 12 7.2 3.9 34.1 93.4 3.0 M M 19500 -9.5 14.9 305 23 12 7.3 4.0 33.7 92.7 2.6 M M 19000 -8.5 16.7 305 22 11 6.1 3.3 33.2 91.7 2.2 M M 18500 -7.6 18.3 300 21 11 6.3 3.4 32.6 90.6 1.6 M M 18000 -6.7 19.9 300 20 10 6.5 3.6 32.0 89.6 1.1 M M 17500 -5.8 21.6 300 19 10 6.7 3.7 31.5 88.6 0.5 M M 17000 -4.3 24.3 300 17 9 7.6 4.2 30.7 87.3 -0.2 1070 5.4 16500 -3.2 26.2 300 16 8 8.1 4.5 30.4 86.8 -0.5 1020 5.2 16000 -2.0 28.4 300 15 8 8.3 4.6 30.2 86.3 -0.8 970 4.9 15500 -0.7 30.7 300 14 7 9.3 5.1 30.0 86.1 -1.0 916 4.7 15000 0.7 33.3 305 13 7 9.3 5.1 30.0 85.9 -1.1 861 4.4 14500 2.0 35.6 300 12 6 9.0 4.9 29.9 85.7 -1.2 806 4.1 14000 3.3 37.9 300 11 6 9.0 4.9 29.7 85.5 -1.3 751 3.8 13500 4.6 40.3 295 10 5 8.7 4.8 29.6 85.3 -1.5 697 3.5 13000 5.9 42.6 290 9 5 8.7 4.8 29.4 84.9 -1.7 645 3.3 12500 7.1 44.8 280 8 4 8.3 4.5 29.2 84.6 -1.9 593 3.0 12000 8.3 46.9 265 7 4 8.0 4.4 28.9 84.1 -2.2 543 2.8 11500 9.5 49.1 250 6 3 8.0 4.4 28.7 83.6 -2.5 494 2.5 11000 10.7 51.3 240 6 3 7.8 4.3 28.4 83.1 -2.8 443 2.3 10500 11.8 53.2 220 5 3 4.5 2.5 28.1 82.6 -3.1 393 2.0 10250 12.0 53.6 230 5 3 4.9 2.7 27.6 81.6 -3.6 379 1.9 10000 12.7 54.9 225 5 3 10.4 5.7 27.5 81.5 -3.7 352 1.8 9750 13.4 56.1 220 5 2 10.6 5.8 27.5 81.6 -3.7 323 1.6 9500 14.2 57.6 215 4 2 7.6 4.1 27.6 81.6 -3.7 293 1.5 9250 14.5 58.1 220 4 2 4.3 2.3 27.2 80.9 -4.1 275 1.4 9000 15.0 59.0 225 4 2 8.1 4.5 26.9 80.4 -4.4 254 1.3 8750 15.7 60.3 225 4 2 10.2 5.6 26.9 80.4 -4.4 226 1.1 8500 16.3 61.3 230 3 2 6.9 3.8 26.8 80.3 -4.5 199 1.0 8250 16.7 62.1 245 3 2 4.5 2.5 26.5 79.6 -4.9 180 0.9 8000 17.1 62.8 255 3 2 6.5 3.6 26.1 79.0 -5.2 161 0.8 7750 17.6 63.7 260 4 2 7.0 3.9 25.9 78.7 -5.4 137 0.7 7500 18.0 64.4 265 4 2 3.5 1.9 25.6 78.1 -5.8 118 0.6 7250 18.2 64.8 270 5 2 1.1 0.6 25.0 77.0 -6.4 107 0.5 7000 18.3 64.9 280 5 3 3.8 2.1 24.4 75.9 -7.0 95 0.5 6750 18.6 65.5 275 6 3 1.5 0.8 24.0 75.2 -7.4 79 0.4 6500 18.4 65.1 270 6 3 -3.9 -2.1 23.1 73.6 -8.4 77 0.4 6250 18.1 64.6 270 6 3 -4.3 -2.3 22.0 71.7 -9.4 80 0.4 6000 17.8 64.0 270 6 3 -3.7 -2.0 21.0 69.8 -10.5 82 0.4 5750 17.3 63.1 280 6 3 -10.3 -5.7 19.8 67.7 -11.8 89 0.5 5500 16.0 60.8 270 5 2 -22.4 -12.3 17.8 64.1 -13.8 121 0.6 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 09/07/2024 at 0900 MDT | 09/07/2024 at 1200 MDT | CAPE... 0.0 LI... +1.9 | CAPE... +48.9 LI... +1.6 CINH... -0.3 K Index... +19.4 | CINH... -53.8 K Index... +18.7 | 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 -60.8 -77.4 300 26 13 1.1 0.6 | -60.9 -77.6 300 25 13 0.5 0.3 45000 -58.8 -73.8 295 31 16 1.8 1.0 | -59.5 -75.1 295 30 16 2.1 1.2 40000 -55.7 -68.3 290 40 21 6.7 3.7 | -55.9 -68.6 295 38 19 6.6 3.6 38000 -51.9 -61.4 295 36 19 6.3 3.5 | -52.1 -61.8 300 35 18 6.3 3.4 36000 -48.1 -54.6 295 33 17 6.4 3.5 | -48.4 -55.1 305 32 17 6.3 3.4 34000 -44.1 -47.4 300 30 15 6.7 3.7 | -44.2 -47.6 305 30 15 7.2 4.0 32000 -40.1 -40.2 300 27 14 6.8 3.7 | -39.8 -39.6 300 27 14 7.3 4.0 30000 -34.9 -30.8 300 25 13 8.0 4.4 | -34.7 -30.5 295 25 13 7.8 4.3 29000 -32.5 -26.5 300 25 13 8.0 4.4 | -32.3 -26.1 295 25 13 7.8 4.3 28000 -30.1 -22.2 300 24 12 8.4 4.6 | -30.0 -22.0 290 24 12 8.4 4.6 27000 -27.6 -17.7 300 23 12 8.5 4.7 | -27.4 -17.3 290 23 12 8.6 4.7 26000 -25.0 -13.0 300 23 12 8.5 4.7 | -24.8 -12.6 295 22 11 8.6 4.7 25000 -22.4 -8.3 305 22 11 8.5 4.7 | -22.3 -8.1 295 21 11 8.5 4.7 24000 -20.0 -4.0 305 22 11 8.2 4.5 | -19.8 -3.6 295 20 10 8.2 4.5 23000 -17.5 0.5 305 21 11 8.2 4.5 | -17.3 0.9 295 19 10 8.2 4.5 22000 -15.1 4.8 305 21 11 7.8 4.3 | -14.9 5.2 295 19 10 7.9 4.3 21000 -12.9 8.8 305 21 11 7.1 3.9 | -12.7 9.1 300 18 9 7.4 4.0 20000 -10.8 12.6 305 20 10 7.1 3.9 | -10.5 13.1 300 17 9 7.4 4.1 19500 -9.7 14.5 305 20 10 7.3 4.0 | -9.4 15.1 300 17 9 7.6 4.2 19000 -8.8 16.2 305 19 10 5.4 3.0 | -8.4 16.9 300 16 8 5.8 3.2 18500 -8.0 17.6 305 18 9 5.7 3.1 | -7.5 18.5 300 16 8 5.9 3.3 18000 -7.2 19.0 305 17 9 5.9 3.2 | -6.6 20.1 300 15 8 5.7 3.1 17500 -6.3 20.7 305 15 8 6.1 3.3 | -5.9 21.4 300 14 7 5.5 3.0 17000 -5.1 22.8 305 13 7 7.5 4.1 | -5.1 22.8 300 14 7 5.5 3.0 16500 -3.9 25.0 305 12 6 8.3 4.6 | -3.8 25.2 300 13 7 7.0 3.8 16000 -2.7 27.1 305 11 6 8.5 4.7 | -2.8 27.0 295 12 6 7.3 4.0 15500 -1.3 29.7 310 10 5 9.2 5.1 | -1.6 29.1 300 11 6 8.8 4.8 15000 0.0 32.0 315 10 5 9.2 5.0 | -0.4 31.3 300 10 5 8.7 4.8 14500 1.3 34.3 315 9 5 9.0 5.0 | 0.9 33.6 305 9 5 9.0 4.9 14000 2.7 36.9 320 9 5 9.1 5.0 | 2.3 36.1 310 9 5 9.0 4.9 13500 4.0 39.2 320 9 5 9.0 4.9 | 3.6 38.5 315 9 5 9.0 4.9 13000 5.3 41.5 320 9 5 9.0 4.9 | 4.9 40.8 320 9 5 9.0 4.9 12500 6.7 44.1 315 9 5 8.5 4.7 | 6.2 43.2 325 10 5 9.0 4.9 12000 7.9 46.2 315 9 5 8.3 4.5 | 7.6 45.7 325 10 5 8.9 4.9 11500 9.1 48.4 310 9 5 8.1 4.5 | 8.9 48.0 330 10 5 8.8 4.8 11000 10.2 50.4 310 8 4 7.8 4.3 | 10.2 50.4 330 9 5 8.5 4.6 10500 11.4 52.5 305 8 4 3.9 2.1 | 11.5 52.7 335 9 5 3.7 2.0 10250 11.5 52.7 305 8 4 4.5 2.4 | 11.6 52.9 335 10 5 5.0 2.8 10000 12.2 54.0 305 8 4 11.0 6.1 | 12.4 54.3 340 9 5 12.3 6.7 9750 13.0 55.4 305 7 4 11.1 6.1 | 13.2 55.8 340 9 4 11.2 6.1 9500 13.7 56.7 305 7 3 7.5 4.1 | 13.9 57.0 340 8 4 8.0 4.4 9250 14.1 57.4 305 7 3 3.9 2.1 | 14.3 57.7 340 8 4 5.1 2.8 9000 14.5 58.1 305 7 3 8.4 4.6 | 14.8 58.6 345 8 4 9.3 5.1 8750 15.3 59.5 305 6 3 10.7 5.9 | 15.6 60.1 345 7 4 11.0 6.0 8500 15.9 60.6 305 6 3 6.8 3.8 | 16.3 61.3 350 7 3 7.9 4.3 8250 16.3 61.3 310 7 3 4.4 2.4 | 16.8 62.2 350 7 3 5.5 3.0 8000 16.7 62.1 315 7 3 6.6 3.6 | 17.3 63.1 355 7 3 8.5 4.6 7750 17.3 63.1 315 7 3 7.0 3.8 | 18.0 64.4 360 6 3 10.3 5.6 7500 17.7 63.9 315 7 3 3.7 2.0 | 18.7 65.7 005 5 3 7.8 4.3 7250 17.8 64.0 315 6 3 1.8 1.0 | 19.2 66.6 010 5 3 6.0 3.3 7000 18.0 64.4 315 6 3 4.4 2.4 | 19.7 67.5 010 5 3 9.4 5.2 6750 18.4 65.1 315 6 3 2.9 1.6 | 20.5 68.9 015 5 3 12.3 6.8 6500 18.3 64.9 315 5 2 -1.1 -0.6 | 21.4 70.5 020 5 2 10.4 5.7 6250 18.2 64.8 315 4 2 -0.5 -0.3 | 22.1 71.8 020 5 2 10.5 5.8 6000 18.2 64.8 315 3 2 -1.5 -0.8 | 22.9 73.2 020 4 2 8.9 4.9 5750 18.1 64.6 320 2 1 4.5 2.5 | 23.6 74.5 025 4 2 14.5 8.0 5500 18.9 66.0 315 1 1 17.1 9.4 | 25.2 77.4 025 4 2 29.0 15.9 09/07/2024 at 1500 MDT | 09/07/2024 at 1800 MDT | CAPE... +109.5 LI... +0.5 | CAPE... +105.3 LI... -0.2 CINH... -47.5 K Index... +19.2 | CINH... -26.8 K Index... +23.8 | 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 -60.7 -77.3 300 26 13 0.4 0.2 | -60.6 -77.1 305 26 14 0.8 0.4 45000 -59.5 -75.1 290 31 16 1.6 0.9 | -59.3 -74.7 295 34 18 0.9 0.5 40000 -56.6 -69.9 300 39 20 7.0 3.9 | -57.4 -71.3 290 41 21 7.8 4.3 38000 -52.6 -62.7 300 36 19 6.6 3.6 | -53.1 -63.6 295 37 19 7.2 3.9 36000 -48.7 -55.7 305 34 18 6.6 3.6 | -48.8 -55.8 300 33 17 7.2 4.0 34000 -44.3 -47.7 305 31 16 7.5 4.1 | -44.1 -47.4 300 30 16 8.0 4.4 32000 -39.8 -39.6 305 27 14 7.5 4.1 | -39.3 -38.7 305 28 14 8.0 4.4 30000 -34.6 -30.3 300 25 13 7.7 4.3 | -34.1 -29.4 300 26 13 7.5 4.1 29000 -32.3 -26.1 295 25 13 7.7 4.3 | -31.9 -25.4 300 26 13 7.5 4.1 28000 -30.0 -22.0 290 25 13 8.2 4.5 | -29.6 -21.3 300 25 13 8.0 4.4 27000 -27.4 -17.3 290 24 12 8.4 4.6 | -27.2 -17.0 300 25 13 8.2 4.5 26000 -24.9 -12.8 295 23 12 8.4 4.6 | -24.7 -12.5 300 24 12 8.2 4.5 25000 -22.4 -8.3 295 22 11 8.4 4.6 | -22.3 -8.1 300 24 12 8.1 4.4 24000 -20.1 -4.2 295 21 11 8.1 4.4 | -20.0 -4.0 300 23 12 7.4 4.1 23000 -17.5 0.5 295 20 10 8.1 4.4 | -17.8 -0.0 300 22 11 7.4 4.1 22000 -15.1 4.8 295 20 10 7.7 4.2 | -15.7 3.7 295 21 11 7.4 4.0 21000 -13.0 8.6 290 20 10 7.0 3.8 | -13.5 7.7 290 21 11 7.2 4.0 20000 -11.0 12.2 290 19 10 7.1 3.9 | -11.4 11.5 290 22 11 7.3 4.0 19500 -9.9 14.2 290 19 10 7.1 3.9 | -10.4 13.3 285 22 11 7.3 4.0 19000 -8.9 16.0 290 19 10 7.1 3.9 | -9.3 15.3 285 22 11 7.8 4.3 18500 -7.9 17.8 290 19 10 7.1 3.9 | -8.2 17.2 285 22 11 7.8 4.3 18000 -6.8 19.8 290 19 10 7.2 4.0 | -7.0 19.4 285 21 11 7.9 4.3 17500 -5.8 21.6 290 19 10 7.4 4.0 | -5.9 21.4 285 20 10 8.1 4.4 17000 -4.7 23.5 290 19 10 7.3 4.0 | -4.7 23.5 290 18 9 8.1 4.4 16500 -3.6 25.5 290 18 9 8.0 4.4 | -3.5 25.7 290 16 8 8.3 4.6 16000 -1.9 28.6 295 17 9 8.0 4.4 | -1.7 28.9 290 13 7 8.4 4.6 15500 -0.7 30.7 295 15 8 8.0 4.4 | -0.5 31.1 290 11 6 8.8 4.8 15000 0.4 32.7 300 13 7 8.0 4.4 | 0.8 33.4 295 9 5 8.8 4.8 14500 1.7 35.1 300 11 6 9.0 4.9 | 2.2 36.0 295 7 4 9.2 5.0 14000 3.0 37.4 305 10 5 8.9 4.9 | 3.5 38.3 300 5 3 9.2 5.0 13500 4.3 39.7 310 8 4 9.1 5.0 | 4.9 40.8 305 3 2 9.0 4.9 13000 5.6 42.1 315 7 4 9.2 5.0 | 6.2 43.2 320 2 1 9.0 4.9 12500 7.0 44.6 320 6 3 9.2 5.0 | 7.5 45.5 350 2 1 9.1 5.0 12000 8.3 46.9 330 5 3 9.2 5.0 | 8.9 48.0 025 2 1 9.2 5.0 11500 9.7 49.5 340 5 2 9.3 5.1 | 10.3 50.5 050 3 1 9.3 5.1 11000 11.1 52.0 350 4 2 9.0 4.9 | 11.7 53.1 055 3 2 9.0 5.0 10500 12.5 54.5 360 4 2 4.0 2.2 | 13.1 55.6 060 4 2 3.7 2.0 10250 12.6 54.7 355 4 2 6.0 3.3 | 13.1 55.6 060 4 2 5.6 3.0 10000 13.5 56.3 005 4 2 13.8 7.6 | 14.1 57.4 065 4 2 13.8 7.6 9750 14.4 57.9 010 4 2 12.7 7.0 | 15.0 59.0 065 5 2 12.6 6.9 9500 15.3 59.5 020 4 2 9.2 5.0 | 15.9 60.6 065 5 3 9.2 5.0 9250 15.8 60.4 020 4 2 6.2 3.4 | 16.3 61.3 065 5 3 6.2 3.4 9000 16.4 61.5 020 4 2 10.8 5.9 | 17.0 62.6 065 6 3 10.7 5.9 8750 17.3 63.1 025 5 2 12.3 6.8 | 17.9 64.2 065 6 3 12.6 6.9 8500 18.1 64.6 030 5 2 9.7 5.3 | 18.7 65.7 065 6 3 9.9 5.4 8250 18.7 65.7 030 5 3 7.1 3.9 | 19.3 66.7 065 6 3 6.9 3.8 8000 19.3 66.7 030 5 3 10.3 5.6 | 19.9 67.8 065 6 3 10.1 5.5 7750 20.2 68.4 035 5 3 12.4 6.8 | 20.8 69.4 065 6 3 12.4 6.8 7500 21.1 70.0 040 5 3 9.4 5.1 | 21.6 70.9 065 7 3 9.3 5.1 7250 21.7 71.1 040 5 3 7.3 4.0 | 22.2 72.0 065 7 3 7.0 3.9 7000 22.3 72.1 040 5 3 10.1 5.5 | 22.8 73.0 065 7 4 9.7 5.3 6750 23.2 73.8 040 5 3 12.9 7.1 | 23.7 74.7 065 7 4 12.5 6.9 6500 24.1 75.4 040 5 3 10.9 6.0 | 24.6 76.3 065 7 4 10.5 5.8 6250 24.8 76.6 040 5 3 9.6 5.3 | 25.2 77.4 065 7 4 8.6 4.7 6000 25.6 78.1 040 5 3 10.4 5.7 | 25.9 78.6 065 7 4 10.1 5.6 5750 26.5 79.7 045 5 3 16.5 9.1 | 26.8 80.2 065 7 3 12.1 6.7 5500 28.1 82.6 045 5 3 25.2 13.8 | 27.7 81.9 065 6 3 12.5 6.9 ________________________________________________________________________________ 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