Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
483 UXUS97 KBOU 151231 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0627 MDT Monday, July 15, 2024 This forecast is for Monday, July 15, 2024: If the trigger temperature of 88.1 F/31.2 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1681 ft/min (8.5 m/s) Maximum height of thermals.................. 20585 ft MSL (15234 ft AGL) Forecast maximum temperature................... 97.0 F/36.6 C Time of trigger temperature.................... 0945 MDT Time of overdevelopment........................ 1700 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 13827 ft MSL (8476 ft AGL) Thermal soaring outlook for Tuesday 07/16...... 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....................... 36181 ft MSL (30830 ft AGL) Wave soaring outlook for Tuesday 07/16......... Good Remarks... None Sunrise/Sunset.................... 05:44:42 / 20:26:26 MDT Total possible sunshine........... 14 hr 41 min 44 sec (881 min 44 sec) Altitude of sun at 13:05:34 MDT... 71.54 degrees Upper air data from numerical model forecast valid on 07/15/2024 at 0600 MDT Freezing level.................. 16650 ft MSL (11299 ft AGL) Convective condensation level... 17568 ft MSL (12217 ft AGL) Lifted condensation level....... 18415 ft MSL (13064 ft AGL) Lifted index.................... -3.3 K index......................... +26.0 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 -61.9 -79.4 295 16 8 1.4 0.7 M M M M M 45000 -58.6 -73.5 305 20 10 3.7 2.0 M M M M M 40000 -52.0 -61.6 310 20 10 6.3 3.5 M M M M M 38000 -48.2 -54.8 285 20 10 6.3 3.5 M M M M M 36000 -44.4 -47.9 265 23 12 7.8 4.3 M M M M M 34000 -39.2 -38.6 265 22 11 8.7 4.8 M M M M M 32000 -34.0 -29.2 265 21 11 9.1 5.0 M M M M M 30000 -29.1 -20.4 270 20 10 8.1 4.5 46.5 115.8 7.9 M M 29000 -26.6 -15.9 270 20 10 8.2 4.5 46.0 114.8 7.5 M M 28000 -24.3 -11.7 270 19 10 6.6 3.6 45.3 113.6 7.1 M M 27000 -22.3 -8.1 270 19 10 6.8 3.7 44.1 111.3 6.2 M M 26000 -20.3 -4.5 270 18 9 6.8 3.7 43.0 109.3 5.3 M M 25000 -18.3 -0.9 270 17 9 6.5 3.5 42.0 107.6 4.6 M M 24000 -16.5 2.3 270 16 8 6.0 3.3 40.5 104.9 3.4 M M 23000 -14.7 5.5 270 15 8 6.1 3.3 39.2 102.5 2.2 M M 22000 -13.0 8.6 270 14 7 6.9 3.8 38.0 100.3 1.2 M M 21000 -10.2 13.6 275 14 7 7.6 4.2 36.9 98.4 0.2 M M 20000 -8.0 17.6 280 14 7 7.6 4.2 36.2 97.1 -0.5 1414 7.2 19500 -6.9 19.6 280 14 7 8.0 4.4 35.9 96.6 -0.8 1366 6.9 19000 -5.7 21.7 285 14 7 8.2 4.5 35.6 96.0 -1.1 1315 6.7 18500 -4.5 23.9 285 13 7 8.2 4.5 35.3 95.6 -1.3 1265 6.4 18000 -3.2 26.2 285 14 7 8.5 4.7 35.1 95.1 -1.6 1213 6.2 17500 -2.0 28.4 285 14 7 8.5 4.6 34.9 94.7 -1.8 1161 5.9 17000 -0.8 30.6 285 14 7 8.6 4.7 34.7 94.4 -2.0 1109 5.6 16500 0.5 32.9 285 14 7 8.7 4.8 34.5 94.0 -2.2 1056 5.4 16000 1.8 35.2 285 14 7 8.8 4.8 34.3 93.7 -2.4 1003 5.1 15500 3.1 37.6 285 14 7 9.0 4.9 34.1 93.5 -2.6 948 4.8 15000 4.4 39.9 285 15 8 9.0 4.9 34.0 93.2 -2.7 894 4.5 14500 5.8 42.4 285 15 8 9.2 5.1 33.9 93.1 -2.9 839 4.3 14000 7.2 45.0 290 15 8 9.2 5.1 33.8 92.9 -3.0 783 4.0 13500 8.5 47.3 290 16 8 8.9 4.9 33.7 92.7 -3.1 727 3.7 13000 9.8 49.6 290 16 8 8.8 4.8 33.6 92.4 -3.3 673 3.4 12500 11.1 52.0 290 16 8 8.8 4.9 33.4 92.2 -3.4 619 3.1 12000 12.5 54.5 290 17 9 8.9 4.9 33.3 91.9 -3.6 565 2.9 11500 13.8 56.8 290 17 9 8.8 4.8 33.2 91.7 -3.7 510 2.6 11000 15.1 59.2 290 17 9 8.3 4.6 33.0 91.3 -3.9 457 2.3 10500 16.3 61.3 290 18 9 4.0 2.2 32.8 91.1 -4.1 404 2.1 10250 16.5 61.7 290 18 9 5.3 2.9 32.2 89.9 -4.7 392 2.0 10000 17.3 63.1 290 18 9 12.0 6.6 32.2 90.0 -4.7 361 1.8 9750 18.1 64.6 290 19 10 10.7 5.9 32.3 90.2 -4.6 330 1.7 9500 18.8 65.8 290 19 10 9.1 5.0 32.4 90.3 -4.6 299 1.5 9250 19.4 66.9 290 19 10 7.0 3.8 32.2 90.0 -4.8 275 1.4 9000 20.0 68.0 290 20 10 8.3 4.6 32.0 89.7 -5.0 251 1.3 8750 20.6 69.1 290 20 10 8.9 4.9 32.0 89.5 -5.1 224 1.1 8500 21.2 70.2 290 20 10 8.3 4.5 31.9 89.4 -5.2 198 1.0 8250 21.8 71.2 290 20 10 7.9 4.3 31.7 89.1 -5.3 173 0.9 8000 22.4 72.3 290 20 10 7.4 4.1 31.6 88.9 -5.5 148 0.8 7750 22.9 73.2 290 20 10 6.8 3.7 31.4 88.5 -5.7 126 0.6 7500 23.4 74.1 290 19 10 6.4 3.5 31.1 88.1 -6.0 104 0.5 7250 23.8 74.8 290 19 10 5.9 3.2 30.9 87.5 -6.3 83 0.4 7000 24.3 75.7 295 19 10 6.2 3.4 30.6 87.0 -6.6 62 0.3 6750 24.7 76.5 290 17 9 4.8 2.6 30.3 86.5 -6.9 43 0.2 6500 24.9 76.8 290 15 8 2.0 1.1 29.8 85.6 -7.5 29 0.1 6250 24.9 76.8 285 13 7 -0.5 -0.3 29.1 84.4 -8.2 21 0.1 6000 24.9 76.8 285 11 6 4.9 2.7 28.4 83.2 -8.9 13 0.1 5750 25.2 77.4 280 9 4 -5.9 -3.3 28.0 82.3 -9.4 M M 5500 23.4 74.1 260 5 2 -41.5 -22.8 25.4 77.8 -12.0 44 0.2 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 07/15/2024 at 0900 MDT | 07/15/2024 at 1200 MDT | CAPE... +286.0 LI... -1.1 | CAPE... +501.2 LI... -2.2 CINH... -94.2 K Index... +26.7 | CINH... -17.5 K Index... +27.6 | 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 -61.6 -78.9 295 18 9 1.5 0.8 | -61.6 -78.9 310 17 9 1.1 0.6 45000 -58.2 -72.8 300 18 9 3.8 2.1 | -58.5 -73.3 300 19 10 4.1 2.2 40000 -52.1 -61.8 285 17 9 5.8 3.2 | -51.7 -61.1 270 20 10 5.8 3.2 38000 -48.2 -54.8 265 22 12 5.8 3.2 | -48.2 -54.8 260 26 13 5.8 3.2 36000 -44.6 -48.3 250 29 15 7.8 4.3 | -44.7 -48.5 260 32 16 7.0 3.9 34000 -39.3 -38.7 250 27 14 8.8 4.8 | -39.5 -39.1 250 31 16 8.8 4.8 32000 -34.0 -29.2 250 25 13 9.0 5.0 | -34.2 -29.6 245 30 16 9.4 5.1 30000 -29.3 -20.7 255 23 12 7.8 4.3 | -29.0 -20.2 250 28 14 7.6 4.2 29000 -27.0 -16.6 255 22 11 7.8 4.3 | -26.8 -16.2 250 27 14 7.6 4.2 28000 -24.7 -12.5 255 21 11 7.1 3.9 | -24.6 -12.3 250 25 13 6.6 3.6 27000 -22.6 -8.7 255 20 10 7.2 4.0 | -22.6 -8.7 255 24 12 6.7 3.7 26000 -20.4 -4.7 255 19 10 7.2 4.0 | -20.6 -5.1 255 23 12 6.7 3.7 25000 -18.3 -0.9 255 18 9 6.7 3.7 | -18.7 -1.7 255 22 11 6.8 3.7 24000 -16.5 2.3 255 18 9 6.1 3.3 | -16.7 1.9 260 21 11 6.8 3.7 23000 -14.7 5.5 255 17 9 6.1 3.3 | -14.7 5.5 260 19 10 6.9 3.8 22000 -12.9 8.8 255 16 8 6.9 3.8 | -12.7 9.1 260 18 9 7.0 3.9 21000 -10.8 12.6 255 15 8 7.4 4.1 | -10.6 12.9 260 17 9 7.1 3.9 20000 -8.0 17.6 260 13 7 7.5 4.1 | -8.6 16.5 260 16 8 7.2 3.9 19500 -6.9 19.6 260 12 6 7.9 4.3 | -7.5 18.5 260 16 8 7.4 4.0 19000 -5.8 21.6 265 12 6 8.0 4.4 | -6.4 20.5 265 15 8 7.8 4.3 18500 -4.6 23.7 265 11 6 8.1 4.4 | -5.3 22.5 265 14 7 7.8 4.3 18000 -3.4 25.9 275 11 6 8.2 4.5 | -4.1 24.6 270 14 7 8.2 4.5 17500 -2.2 28.0 280 11 6 8.2 4.5 | -2.9 26.8 275 13 6 8.3 4.6 17000 -1.0 30.2 285 11 6 8.3 4.6 | -1.7 28.9 280 12 6 8.5 4.7 16500 0.2 32.4 295 11 6 8.4 4.6 | 0.2 32.4 285 11 5 9.1 5.0 16000 1.4 34.5 305 11 6 8.4 4.6 | 1.6 34.9 290 10 5 9.1 5.0 15500 2.7 36.9 310 12 6 8.7 4.8 | 2.9 37.2 295 10 5 9.0 4.9 15000 4.0 39.2 315 12 6 8.6 4.7 | 4.2 39.6 300 10 5 9.0 4.9 14500 5.3 41.5 325 13 7 8.9 4.9 | 5.6 42.1 305 10 5 9.3 5.1 14000 6.6 43.9 325 14 7 8.9 4.9 | 6.9 44.4 305 10 5 9.3 5.1 13500 7.9 46.2 330 15 8 9.0 4.9 | 8.3 46.9 310 10 5 9.1 5.0 13000 9.2 48.6 335 15 8 9.0 4.9 | 9.6 49.3 310 10 5 9.1 5.0 12500 10.6 51.1 335 16 8 8.9 4.9 | 11.0 51.8 315 10 5 9.0 5.0 12000 11.9 53.4 335 16 8 8.9 4.9 | 12.3 54.1 315 9 5 9.0 4.9 11500 13.2 55.8 340 16 8 8.8 4.8 | 13.6 56.5 320 9 5 8.9 4.9 11000 14.5 58.1 340 16 8 8.4 4.6 | 14.9 58.8 325 8 4 8.6 4.7 10500 15.8 60.4 340 16 8 3.4 1.9 | 16.1 61.0 330 8 4 3.6 2.0 10250 15.9 60.6 345 16 8 4.6 2.5 | 16.3 61.3 335 7 4 6.0 3.3 10000 16.6 61.9 345 16 8 12.1 6.7 | 17.1 62.8 335 7 4 12.7 7.0 9750 17.4 63.3 340 16 8 10.6 5.8 | 18.0 64.4 340 7 4 11.6 6.4 9500 18.2 64.8 335 17 9 9.1 5.0 | 18.8 65.8 345 7 3 8.4 4.6 9250 18.8 65.8 340 17 9 7.5 4.1 | 19.2 66.6 350 7 3 7.4 4.1 9000 19.4 66.9 340 17 9 9.3 5.1 | 20.0 68.0 355 7 3 11.5 6.3 8750 20.1 68.2 335 17 9 9.8 5.4 | 20.8 69.4 350 7 3 11.8 6.5 8500 20.9 69.6 330 17 9 9.2 5.1 | 21.6 70.9 355 7 3 10.0 5.5 8250 21.5 70.7 330 18 9 8.8 4.8 | 22.3 72.1 355 7 3 8.3 4.5 8000 22.2 72.0 330 18 10 8.9 4.9 | 22.9 73.2 360 7 3 10.0 5.5 7750 22.9 73.2 325 18 9 8.6 4.7 | 23.7 74.7 355 7 3 10.8 5.9 7500 23.5 74.3 325 18 9 6.9 3.8 | 24.5 76.1 355 7 3 9.2 5.1 7250 23.9 75.0 320 18 9 5.5 3.0 | 25.1 77.2 360 7 3 8.0 4.4 7000 24.4 75.9 315 19 10 6.9 3.8 | 25.8 78.4 360 7 3 10.3 5.6 6750 24.9 76.8 315 18 9 8.2 4.5 | 26.7 80.1 360 6 3 12.8 7.0 6500 25.5 77.9 310 16 8 6.8 3.7 | 27.6 81.7 360 6 3 11.1 6.1 6250 25.9 78.6 310 14 7 6.6 3.6 | 28.3 82.9 005 6 3 10.6 5.8 6000 26.3 79.3 305 12 6 4.7 2.6 | 29.1 84.4 005 6 3 9.3 5.1 5750 26.6 79.9 305 9 5 10.1 5.5 | 29.9 85.8 360 6 3 15.2 8.3 5500 27.9 82.2 300 8 4 25.2 13.8 | 31.5 88.7 005 6 3 29.6 16.2 07/15/2024 at 1500 MDT | 07/15/2024 at 1800 MDT | CAPE... +499.9 LI... -2.3 | CAPE... +401.0 LI... -1.5 CINH... -12.7 K Index... +31.6 | CINH... -53.4 K Index... +30.2 | 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 -61.6 -78.9 310 14 7 1.8 1.0 | -62.1 -79.8 320 14 7 1.6 0.9 45000 -58.0 -72.4 295 16 8 3.5 1.9 | -58.2 -72.8 295 17 9 4.3 2.4 40000 -51.5 -60.7 265 23 12 7.0 3.8 | -50.9 -59.6 260 24 12 6.1 3.4 38000 -47.3 -53.1 265 29 15 7.0 3.8 | -47.2 -53.0 265 28 15 6.1 3.4 36000 -43.1 -45.6 265 35 18 7.4 4.1 | -43.5 -46.3 265 33 17 7.3 4.0 34000 -38.5 -37.3 265 35 18 7.7 4.2 | -38.6 -37.5 270 34 18 8.1 4.5 32000 -33.8 -28.8 260 35 18 8.2 4.5 | -33.7 -28.7 270 35 18 8.6 4.7 30000 -29.6 -21.3 265 32 17 7.0 3.8 | -29.4 -20.9 270 32 17 7.2 4.0 29000 -27.6 -17.7 265 31 16 7.0 3.8 | -27.2 -17.0 265 31 16 7.2 4.0 28000 -25.5 -13.9 265 29 15 7.2 3.9 | -25.1 -13.2 265 29 15 7.2 3.9 27000 -23.4 -10.1 265 26 14 7.2 3.9 | -23.0 -9.4 265 28 14 7.2 3.9 26000 -21.2 -6.2 265 24 12 7.2 4.0 | -20.8 -5.4 265 26 13 7.2 4.0 25000 -19.1 -2.4 265 21 11 7.1 3.9 | -18.7 -1.7 265 24 12 7.3 4.0 24000 -17.0 1.4 270 20 10 7.0 3.8 | -16.5 2.3 265 23 12 7.3 4.0 23000 -15.0 5.0 270 19 10 7.0 3.8 | -14.4 6.1 265 21 11 7.4 4.0 22000 -12.4 9.7 275 18 9 7.3 4.0 | -12.2 10.0 270 20 10 7.5 4.1 21000 -10.3 13.5 275 17 9 7.3 4.0 | -9.5 14.9 275 18 9 7.6 4.2 20000 -8.2 17.2 280 17 9 7.3 4.0 | -7.2 19.0 280 17 9 7.6 4.2 19500 -7.1 19.2 280 16 8 7.6 4.2 | -6.1 21.0 280 17 9 7.8 4.3 19000 -6.0 21.2 280 15 8 7.7 4.2 | -5.0 23.0 285 16 8 7.9 4.3 18500 -4.9 23.2 280 14 7 7.7 4.3 | -3.9 25.0 290 15 8 8.0 4.4 18000 -3.7 25.3 285 13 7 8.2 4.5 | -2.8 27.0 290 14 7 7.1 3.9 17500 -2.5 27.5 285 11 6 8.1 4.5 | -1.7 28.9 295 13 6 7.2 4.0 17000 -1.3 29.7 285 10 5 8.5 4.7 | -0.7 30.7 295 11 6 7.2 3.9 16500 -0.1 31.8 290 9 5 8.7 4.8 | 0.3 32.5 295 9 5 7.1 3.9 16000 1.2 34.2 290 8 4 8.8 4.8 | 1.4 34.5 290 8 4 7.2 4.0 15500 2.5 36.5 295 7 3 9.1 5.0 | 2.5 36.5 290 6 3 7.9 4.3 15000 3.9 39.0 295 6 3 9.1 5.0 | 3.6 38.5 280 5 3 7.7 4.2 14500 5.2 41.4 300 5 3 9.5 5.2 | 4.8 40.6 275 4 2 9.1 5.0 14000 6.6 43.9 300 5 2 9.5 5.2 | 6.2 43.2 270 3 2 9.1 5.0 13500 8.0 46.4 305 4 2 9.4 5.2 | 7.5 45.5 265 3 1 9.2 5.1 13000 9.4 48.9 305 4 2 9.4 5.2 | 8.9 48.0 270 2 1 9.3 5.1 12500 10.8 51.4 310 4 2 9.5 5.2 | 10.3 50.5 275 2 1 9.2 5.0 12000 12.3 54.1 310 4 2 9.7 5.3 | 11.6 52.9 300 1 1 9.1 5.0 11500 13.7 56.7 315 3 2 9.7 5.3 | 13.0 55.4 320 2 1 8.9 4.9 11000 15.2 59.4 315 3 2 9.4 5.1 | 14.3 57.7 335 2 1 8.4 4.6 10500 16.6 61.9 320 3 2 4.0 2.2 | 15.6 60.1 340 2 1 5.2 2.9 10250 16.7 62.1 310 2 1 5.7 3.2 | 15.8 60.4 360 2 1 6.1 3.4 10000 17.6 63.7 315 2 1 13.9 7.6 | 16.6 61.9 355 2 1 11.1 6.1 9750 18.6 65.5 320 2 1 12.7 6.9 | 17.3 63.1 350 3 1 10.0 5.5 9500 19.5 67.1 325 3 1 9.6 5.3 | 18.1 64.6 345 3 1 9.6 5.3 9250 20.0 68.0 325 1 1 7.3 4.0 | 18.8 65.8 360 3 1 8.4 4.6 9000 20.7 69.3 325 1 1 10.9 6.0 | 19.4 66.9 360 2 1 8.4 4.6 8750 21.6 70.9 325 2 1 11.7 6.4 | 20.0 68.0 350 2 1 8.3 4.6 8500 22.4 72.3 325 2 1 10.2 5.6 | 20.6 69.1 340 2 1 8.9 4.9 8250 23.1 73.6 335 1 0 8.2 4.5 | 21.3 70.3 350 2 1 10.0 5.5 8000 23.7 74.7 000 0 0 9.9 5.5 | 22.0 71.6 005 2 1 8.7 4.8 7750 24.6 76.3 330 1 0 11.8 6.5 | 22.6 72.7 345 2 1 7.2 3.9 7500 25.4 77.7 325 2 1 9.4 5.1 | 23.1 73.6 325 2 1 8.2 4.5 7250 26.0 78.8 335 1 0 7.0 3.8 | 23.7 74.7 350 1 1 8.8 4.8 7000 26.5 79.7 120 1 0 9.2 5.1 | 24.4 75.9 020 1 1 8.7 4.8 6750 27.4 81.3 000 0 0 12.5 6.8 | 25.0 77.0 010 1 1 9.5 5.2 6500 28.3 82.9 320 1 1 11.2 6.1 | 25.7 78.3 350 1 1 10.8 5.9 6250 29.0 84.2 000 0 0 9.7 5.3 | 26.6 79.9 020 1 1 11.9 6.5 6000 29.8 85.6 130 1 0 9.4 5.1 | 27.4 81.3 040 1 1 10.0 5.5 5750 30.5 86.9 140 1 0 12.8 7.0 | 28.1 82.6 040 2 1 10.0 5.5 5500 31.8 89.2 000 0 0 22.0 12.0 | 29.1 84.4 050 2 1 17.2 9.4 ________________________________________________________________________________ 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