UXUS97 KBOU 150117 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1917 MDT Tuesday, April 14, 2026 This forecast is for Wednesday, April 15, 2026: If the trigger temperature of 54.6 F/12.5 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1484 ft/min (7.5 m/s) Maximum height of thermals.................. 21262 ft MSL (15902 ft AGL) Forecast maximum temperature................... 69.0 F/21.0 C Time of trigger temperature.................... 1015 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................. 16381 ft MSL (11021 ft AGL) Thermal soaring outlook for Thursday 04/16..... Excellent Wave Soaring Index............................. Poor Wave Soaring Index trend (to 1800 MDT)......... Slight increase Height of stable layer (12-18K ft MSL)......... None Weak PVA/NVA (through 1800 MDT)................ Weak NVA Potential height of wave....................... 26540 ft MSL (21180 ft AGL) Wave soaring outlook for Thursday 04/16........ Poor Remarks... Sunrise/Sunset.................... 06:21:18 / 19:37:34 MDT Total possible sunshine........... 13 hr 16 min 16 sec (796 min 16 sec) Altitude of sun at 12:59:26 MDT... 60.21 degrees Upper air data from numerical model forecast valid on 04/15/2026 at 0600 MDT Freezing level.................. 9605 ft MSL (4245 ft AGL) Convective condensation level... 14980 ft MSL (9620 ft AGL) Lifted condensation level....... 17002 ft MSL (11642 ft AGL) Lifted index.................... -2.9 K index......................... +5.6 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 -57.8 -72.0 230 44 23 1.4 0.8 M M M M M 45000 -55.7 -68.3 235 48 25 1.4 0.7 M M M M M 40000 -52.8 -63.0 240 37 19 1.9 1.1 M M M M M 38000 -51.8 -61.2 240 31 16 0.7 0.4 M M M M M 36000 -51.4 -60.5 245 25 13 0.7 0.4 M M M M M 34000 -50.9 -59.6 255 20 10 0.8 0.4 M M M M M 32000 -50.4 -58.7 295 10 5 0.9 0.5 M M M M M 30000 -49.8 -57.6 360 12 6 5.3 2.9 25.4 77.7 3.6 M M 29000 -47.5 -53.5 360 14 7 7.7 4.2 24.4 75.9 2.9 M M 28000 -45.2 -49.4 355 15 8 7.7 4.2 23.5 74.4 2.3 M M 27000 -42.9 -45.2 350 16 8 7.6 4.2 22.9 73.1 1.8 M M 26000 -40.3 -40.5 350 16 8 9.2 5.0 22.4 72.3 1.4 M M 25000 -37.5 -35.5 345 15 8 9.2 5.1 22.2 71.9 1.3 M M 24000 -34.7 -30.5 340 15 8 9.2 5.1 22.0 71.7 1.2 M M 23000 -32.1 -25.8 335 15 8 8.2 4.5 21.6 70.9 0.8 M M 22000 -29.7 -21.5 330 15 8 8.2 4.5 21.0 69.8 0.3 M M 21000 -27.2 -17.0 325 16 8 8.2 4.5 20.5 69.0 -0.1 1469 7.5 20000 -24.2 -11.6 330 16 8 8.0 4.4 19.7 67.5 -0.7 1341 6.8 19500 -23.0 -9.4 330 16 8 8.0 4.4 19.4 67.0 -1.0 1290 6.6 19000 -21.8 -7.2 335 17 9 8.0 4.4 19.1 66.5 -1.2 1239 6.3 18500 -20.6 -5.1 335 17 9 7.7 4.2 18.9 66.0 -1.5 1188 6.0 18000 -19.5 -3.1 335 17 9 7.3 4.0 18.5 65.2 -1.8 1140 5.8 17500 -18.4 -1.1 340 17 9 7.3 4.0 18.1 64.5 -2.2 1093 5.6 17000 -17.3 0.9 335 17 9 7.5 4.1 17.7 63.8 -2.6 1045 5.3 16500 -16.2 2.8 335 16 8 7.5 4.1 17.3 63.1 -3.0 996 5.1 16000 -15.1 4.8 335 16 8 6.8 3.7 16.9 62.4 -3.3 949 4.8 15500 -14.1 6.6 330 15 8 6.7 3.7 16.3 61.4 -3.9 905 4.6 15000 -13.1 8.4 325 14 7 6.8 3.8 15.8 60.5 -4.4 862 4.4 14500 -12.1 10.2 325 12 6 7.0 3.9 15.4 59.6 -4.9 816 4.1 14000 -11.1 12.0 320 11 6 7.2 4.0 14.9 58.8 -5.3 771 3.9 13500 -10.0 14.0 320 10 5 7.8 4.3 14.5 58.2 -5.7 723 3.7 13000 -8.9 16.0 320 8 4 7.8 4.3 14.2 57.6 -6.1 674 3.4 12500 -7.6 18.3 320 8 4 8.6 4.7 14.0 57.2 -6.4 622 3.2 12000 -6.4 20.5 325 8 4 8.6 4.7 13.8 56.8 -6.6 570 2.9 11500 -5.0 23.0 325 8 4 9.1 5.0 13.6 56.6 -6.8 515 2.6 11000 -3.7 25.3 330 8 4 8.9 4.9 13.5 56.4 -6.9 460 2.3 10500 -2.5 27.5 330 9 4 7.4 4.1 13.3 55.9 -7.2 409 2.1 10250 -1.9 28.6 330 9 5 7.9 4.3 13.1 55.6 -7.4 385 2.0 10000 -1.3 29.7 330 9 5 10.3 5.7 13.0 55.4 -7.5 358 1.8 9750 -0.5 31.1 325 9 5 9.8 5.4 13.1 55.6 -7.4 327 1.7 9500 0.1 32.2 325 10 5 8.0 4.4 13.0 55.4 -7.6 301 1.5 9250 0.8 33.4 320 10 5 8.5 4.7 12.9 55.2 -7.7 275 1.4 9000 1.4 34.5 320 10 5 8.2 4.5 12.8 55.0 -7.8 248 1.3 8750 2.0 35.6 315 11 6 8.2 4.5 12.7 54.8 -8.0 223 1.1 8500 2.6 36.7 310 11 6 8.2 4.5 12.5 54.6 -8.1 197 1.0 8250 3.2 37.8 310 12 6 8.2 4.5 12.4 54.3 -8.3 172 0.9 8000 3.8 38.8 305 13 6 8.3 4.6 12.3 54.1 -8.4 146 0.7 7750 4.4 39.9 300 13 7 7.8 4.3 12.2 53.9 -8.6 120 0.6 7500 5.0 41.0 300 14 7 7.6 4.2 12.0 53.6 -8.8 96 0.5 7250 5.5 41.9 295 15 8 7.2 3.9 11.8 53.3 -9.0 72 0.4 7000 6.0 42.8 290 16 8 6.3 3.4 11.6 52.9 -9.2 50 0.3 6750 6.5 43.7 290 18 9 5.5 3.0 11.3 52.4 -9.5 30 0.2 6500 6.8 44.2 290 19 10 5.5 3.0 11.0 51.8 -9.9 11 0.1 6250 7.2 45.0 285 20 10 2.7 1.5 10.6 51.1 -10.3 M M 6000 7.2 45.0 285 17 9 -0.1 -0.0 9.9 49.8 -11.1 M M 5750 7.2 45.0 280 15 8 1.3 0.7 9.2 48.6 -11.8 M M 5500 7.2 45.0 275 12 6 -2.2 -1.2 8.5 47.3 -12.6 M M * * * * * * Numerical weather prediction model forecast data valid * * * * * * 04/15/2026 at 0900 MDT | 04/15/2026 at 1200 MDT | CAPE... 0.0 LI... +2.7 | CAPE... +0.7 LI... +2.4 CINH... -0.2 K Index... +4.9 | CINH... -0.0 K Index... +2.0 | 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 -57.8 -72.0 235 40 21 1.3 0.7 | -58.5 -73.3 235 42 21 1.5 0.8 45000 -55.9 -68.6 245 41 21 1.3 0.7 | -56.2 -69.2 245 41 21 1.7 0.9 40000 -53.8 -64.8 250 29 15 1.4 0.8 | -55.4 -67.7 270 26 13 0.5 0.3 38000 -53.2 -63.8 265 23 12 0.4 0.2 | -55.0 -67.0 295 22 11 0.7 0.4 36000 -52.9 -63.2 300 20 10 0.4 0.2 | -54.6 -66.3 330 26 13 0.7 0.4 34000 -52.7 -62.9 330 24 12 2.6 1.4 | -53.9 -65.0 350 36 18 5.6 3.1 32000 -50.4 -58.7 345 26 13 3.8 2.1 | -50.3 -58.5 350 34 18 6.1 3.4 30000 -48.0 -54.4 350 28 14 6.4 3.5 | -46.5 -51.7 345 33 17 7.6 4.2 29000 -45.9 -50.6 345 25 13 7.1 3.9 | -44.3 -47.7 345 31 16 7.5 4.1 28000 -43.8 -46.8 340 22 11 7.1 3.9 | -42.0 -43.6 345 28 15 7.5 4.1 27000 -41.7 -43.1 335 20 10 7.0 3.8 | -39.8 -39.6 345 26 13 7.5 4.1 26000 -39.3 -38.7 330 18 10 8.3 4.6 | -37.5 -35.5 340 24 12 7.7 4.2 25000 -36.8 -34.2 325 18 9 8.3 4.6 | -35.1 -31.2 335 21 11 7.7 4.2 24000 -34.3 -29.7 320 17 9 8.3 4.6 | -32.8 -27.0 335 19 10 7.7 4.2 23000 -31.8 -25.2 315 16 8 8.1 4.4 | -30.5 -22.9 325 17 9 7.6 4.1 22000 -29.4 -20.9 315 15 8 8.1 4.4 | -28.3 -18.9 315 16 8 7.6 4.1 21000 -26.4 -15.5 315 14 7 7.7 4.2 | -25.4 -13.7 300 15 8 7.7 4.2 20000 -24.1 -11.4 315 14 7 7.6 4.2 | -23.1 -9.6 295 15 8 7.8 4.3 19500 -23.0 -9.4 315 14 7 7.6 4.2 | -21.9 -7.4 290 16 8 7.8 4.3 19000 -21.9 -7.4 315 14 7 7.6 4.2 | -20.7 -5.3 285 16 8 7.8 4.3 18500 -20.7 -5.3 315 14 7 7.6 4.2 | -19.6 -3.3 280 16 8 7.5 4.1 18000 -19.6 -3.3 315 14 7 7.6 4.1 | -18.5 -1.3 280 16 8 7.3 4.0 17500 -18.5 -1.3 315 14 7 7.6 4.2 | -17.4 0.7 280 16 8 7.3 4.0 17000 -17.4 0.7 315 13 7 7.5 4.1 | -16.3 2.7 275 15 8 6.9 3.8 16500 -16.2 2.8 315 13 7 7.6 4.2 | -15.3 4.5 275 14 7 7.0 3.8 16000 -15.1 4.8 315 13 7 7.1 3.9 | -14.3 6.3 270 14 7 6.9 3.8 15500 -14.1 6.6 315 12 6 7.1 3.9 | -13.3 8.1 270 12 6 6.9 3.8 15000 -13.0 8.6 310 11 6 7.3 4.0 | -12.2 10.0 265 11 6 7.1 3.9 14500 -12.0 10.4 305 11 6 7.4 4.1 | -11.2 11.8 265 11 6 7.3 4.0 14000 -10.9 12.4 305 10 5 7.6 4.1 | -10.1 13.8 265 11 6 7.3 4.0 13500 -9.7 14.5 295 10 5 7.8 4.3 | -9.0 15.8 265 11 6 7.4 4.0 13000 -8.6 16.5 290 9 5 7.8 4.3 | -8.0 17.6 265 11 6 7.7 4.2 12500 -7.4 18.7 285 9 5 8.1 4.4 | -6.7 19.9 265 11 6 8.4 4.6 12000 -6.2 20.8 285 9 5 8.1 4.5 | -5.5 22.1 265 12 6 8.5 4.7 11500 -5.0 23.0 285 9 4 8.5 4.7 | -4.2 24.4 265 12 6 8.9 4.9 11000 -3.7 25.3 285 9 4 8.2 4.5 | -2.9 26.8 270 12 6 8.6 4.7 10500 -2.6 27.3 285 8 4 6.6 3.6 | -1.7 28.9 275 11 6 7.5 4.1 10250 -2.1 28.2 280 8 4 7.2 4.0 | -1.1 30.0 280 11 6 9.0 4.9 10000 -1.5 29.3 285 8 4 10.3 5.7 | -0.3 31.5 280 11 6 11.2 6.1 9750 -0.7 30.7 285 9 5 9.7 5.3 | 0.5 32.9 280 12 6 10.2 5.6 9500 -0.1 31.8 285 10 5 7.4 4.1 | 1.2 34.2 285 12 6 9.3 5.1 9250 0.5 32.9 280 10 5 8.1 4.5 | 1.9 35.4 285 11 6 9.6 5.3 9000 1.1 34.0 280 10 5 7.6 4.2 | 2.6 36.7 285 11 6 9.4 5.2 8750 1.6 34.9 280 10 5 8.0 4.4 | 3.3 37.9 290 11 6 9.7 5.3 8500 2.3 36.1 280 11 6 8.6 4.7 | 4.0 39.2 290 11 6 9.9 5.4 8250 2.9 37.2 280 12 6 8.5 4.6 | 4.8 40.6 285 11 6 9.9 5.4 8000 3.5 38.3 285 13 6 8.5 4.7 | 5.5 41.9 290 11 6 10.2 5.6 7750 4.2 39.6 285 13 7 7.5 4.1 | 6.3 43.3 290 11 5 10.0 5.5 7500 4.7 40.5 285 14 7 6.9 3.8 | 7.0 44.6 290 11 6 9.9 5.4 7250 5.2 41.4 285 16 8 6.6 3.6 | 7.8 46.0 290 11 6 9.7 5.3 7000 5.6 42.1 285 16 8 5.5 3.0 | 8.5 47.3 290 11 6 9.2 5.0 6750 6.0 42.8 285 15 8 6.8 3.7 | 9.2 48.6 290 10 5 10.4 5.7 6500 6.6 43.9 285 14 7 8.1 4.5 | 10.0 50.0 290 11 5 11.4 6.3 6250 7.2 45.0 285 13 7 9.2 5.1 | 10.9 51.6 290 11 5 10.9 6.0 6000 7.9 46.2 285 12 6 10.6 5.8 | 11.7 53.1 290 10 5 11.4 6.2 5750 8.7 47.7 285 11 6 9.2 5.1 | 12.5 54.5 295 9 5 9.3 5.1 5500 9.4 48.9 280 10 5 11.9 6.5 | 13.3 55.9 290 9 5 14.8 8.1 04/15/2026 at 1500 MDT | 04/15/2026 at 1800 MDT | CAPE... +2.1 LI... +1.3 | CAPE... 0.0 LI... +1.4 CINH... -0.0 K Index... +14.5 | CINH... -0.3 K Index... +14.9 | 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 -59.3 -74.7 240 43 22 1.6 0.9 | -59.0 -74.2 245 42 22 1.3 0.7 45000 -56.9 -70.4 250 38 20 1.7 1.0 | -57.0 -70.6 250 37 19 1.3 0.7 40000 -58.4 -73.1 290 20 10 -1.1 -0.6 | -60.3 -76.5 290 20 10 -2.3 -1.3 38000 -57.8 -72.0 320 21 11 3.4 1.9 | -59.4 -74.9 315 20 10 5.3 2.9 36000 -55.8 -68.4 335 27 14 3.4 1.9 | -56.2 -69.2 325 24 12 5.3 2.9 34000 -53.5 -64.3 345 34 17 7.1 3.9 | -52.8 -63.0 330 27 14 6.9 3.8 32000 -49.5 -57.1 340 30 16 6.7 3.7 | -48.7 -55.7 325 26 14 6.8 3.7 30000 -45.4 -49.7 340 28 14 7.5 4.1 | -44.6 -48.3 325 26 13 7.7 4.2 29000 -43.2 -45.8 335 27 14 7.4 4.1 | -42.2 -44.0 320 25 13 7.7 4.2 28000 -40.9 -41.6 335 26 14 7.4 4.1 | -39.9 -39.8 320 23 12 7.7 4.2 27000 -38.7 -37.7 330 26 13 7.5 4.1 | -37.6 -35.7 320 22 12 7.7 4.2 26000 -36.3 -33.3 330 24 12 8.1 4.4 | -35.3 -31.5 315 22 11 7.9 4.3 25000 -33.9 -29.0 330 22 12 8.1 4.4 | -32.9 -27.2 315 21 11 7.9 4.3 24000 -31.4 -24.5 330 21 11 8.1 4.4 | -30.6 -23.1 310 20 10 7.9 4.3 23000 -29.1 -20.4 325 19 10 7.9 4.3 | -28.2 -18.8 310 20 10 7.9 4.4 22000 -26.7 -16.1 315 17 9 7.9 4.3 | -25.8 -14.4 305 19 10 7.9 4.3 21000 -23.8 -10.8 300 16 8 7.0 3.8 | -22.9 -9.2 300 19 10 7.0 3.9 20000 -21.7 -7.1 290 17 9 6.9 3.8 | -20.8 -5.4 290 19 10 7.1 3.9 19500 -20.7 -5.3 285 18 9 6.9 3.8 | -19.7 -3.5 285 19 10 7.1 3.9 19000 -19.6 -3.3 280 19 10 6.9 3.8 | -18.7 -1.7 280 19 10 7.2 3.9 18500 -18.6 -1.5 275 20 10 6.6 3.6 | -17.6 0.3 275 19 10 6.8 3.7 18000 -17.6 0.3 270 20 10 6.6 3.6 | -16.6 2.1 265 20 10 6.8 3.7 17500 -16.7 1.9 270 20 10 6.8 3.7 | -15.7 3.7 260 21 11 7.1 3.9 17000 -15.6 3.9 270 20 10 7.9 4.3 | -14.6 5.7 255 20 11 7.6 4.2 16500 -14.4 6.1 270 20 11 8.0 4.4 | -13.4 7.9 255 20 10 7.5 4.1 16000 -13.3 8.1 270 20 11 7.3 4.0 | -12.2 10.0 255 19 10 8.6 4.7 15500 -12.2 10.0 270 20 10 7.3 4.0 | -11.0 12.2 255 18 10 8.5 4.7 15000 -11.2 11.8 275 20 10 8.4 4.6 | -9.7 14.5 255 17 9 8.8 4.8 14500 -9.8 14.4 275 19 10 8.8 4.8 | -8.4 16.9 260 16 8 8.8 4.8 14000 -8.5 16.7 275 19 10 8.9 4.9 | -7.1 19.2 260 15 8 8.7 4.8 13500 -7.2 19.0 275 18 9 8.9 4.9 | -5.8 21.6 265 14 7 8.5 4.7 13000 -5.9 21.4 275 17 9 9.0 4.9 | -4.5 23.9 275 14 7 8.6 4.7 12500 -4.5 23.9 275 16 8 9.1 5.0 | -3.2 26.2 280 14 7 8.7 4.8 12000 -3.2 26.2 280 15 8 9.1 5.0 | -2.0 28.4 280 13 7 8.7 4.8 11500 -1.8 28.8 280 14 7 9.0 4.9 | -0.7 30.7 285 13 7 8.8 4.8 11000 -0.5 31.1 280 13 7 8.8 4.8 | 0.7 33.3 285 13 7 8.7 4.8 10500 0.8 33.4 280 12 6 7.8 4.3 | 1.9 35.4 285 13 7 8.1 4.4 10250 1.4 34.5 280 12 6 9.4 5.1 | 2.5 36.5 285 12 6 9.7 5.3 10000 2.2 36.0 280 12 6 10.9 6.0 | 3.3 37.9 285 12 6 10.9 6.0 9750 2.9 37.2 280 12 6 9.8 5.4 | 4.1 39.4 290 12 6 9.6 5.3 9500 3.7 38.7 280 12 6 9.5 5.2 | 4.8 40.6 290 12 6 9.4 5.2 9250 4.4 39.9 280 12 6 9.6 5.3 | 5.5 41.9 290 12 6 9.4 5.2 9000 5.1 41.2 280 12 6 9.4 5.1 | 6.2 43.2 290 12 6 9.4 5.2 8750 5.8 42.4 280 12 6 9.5 5.2 | 6.9 44.4 290 13 6 9.6 5.2 8500 6.5 43.7 280 12 6 9.8 5.4 | 7.6 45.7 290 13 7 9.6 5.3 8250 7.3 45.1 280 12 6 9.8 5.4 | 8.4 47.1 290 13 7 9.7 5.3 8000 8.0 46.4 280 12 6 10.2 5.6 | 9.1 48.4 290 13 7 10.0 5.5 7750 8.8 47.8 280 12 6 10.1 5.6 | 9.8 49.6 290 13 7 9.8 5.4 7500 9.5 49.1 280 12 6 9.8 5.4 | 10.6 51.1 290 13 7 9.4 5.2 7250 10.3 50.5 280 12 6 10.0 5.5 | 11.3 52.3 290 13 7 9.7 5.3 7000 11.0 51.8 280 12 6 10.2 5.6 | 12.0 53.6 290 13 7 10.2 5.6 6750 11.8 53.2 280 12 6 10.3 5.7 | 12.8 55.0 290 13 7 10.0 5.5 6500 12.6 54.7 280 11 6 10.4 5.7 | 13.5 56.3 295 13 7 9.7 5.3 6250 13.3 55.9 280 11 6 10.6 5.8 | 14.2 57.6 295 13 7 10.2 5.6 6000 14.2 57.6 280 11 6 11.3 6.2 | 15.0 59.0 295 13 7 10.7 5.9 5750 15.0 59.0 280 10 5 9.7 5.3 | 15.8 60.4 295 12 6 9.9 5.5 5500 15.8 60.4 280 10 5 15.4 8.4 | 16.6 61.9 295 11 6 11.8 6.5 ________________________________________________________________________________ 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