Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
669 UXUS97 KBOU 211231 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0630 MDT Tuesday, May 21, 2024 This forecast is for Tuesday, May 21, 2024: If the trigger temperature of 55.7 F/13.1 C is reached...then Thermal Soaring Index....................... Poor Maximum rate of lift........................ 53 ft/min (0.3 m/s) Maximum height of thermals.................. 11498 ft MSL (6161 ft AGL) Forecast maximum temperature................... 61.0 F/16.6 C Time of trigger temperature.................... 1100 MDT Time of overdevelopment........................ None Middle/high clouds during soaring window....... Broken/overcast opaque middle Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 9254 ft MSL (3917 ft AGL) Thermal soaring outlook for Wednesday 05/22.... Good Wave Soaring Index............................. Fair 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....................... 16398 ft MSL (11061 ft AGL) Wave soaring outlook for Wednesday 05/22....... Fair Remarks... None Sunrise/Sunset.................... 05:39:09 / 20:13:09 MDT Total possible sunshine........... 14 hr 34 min 0 sec (874 min 0 sec) Altitude of sun at 12:56:09 MDT... 70.61 degrees Upper air data from numerical model forecast valid on 05/21/2024 at 0600 MDT Freezing level.................. 10136 ft MSL (4799 ft AGL) Convective condensation level... 10806 ft MSL (5469 ft AGL) Lifted condensation level....... 11178 ft MSL (5841 ft AGL) Lifted index.................... -0.7 K index......................... +20.7 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 -52.2 -62.0 235 45 23 2.8 1.5 M M M M M 45000 -48.1 -54.6 230 55 29 0.6 0.3 M M M M M 40000 -47.2 -53.0 235 53 27 0.6 0.3 M M M M M 38000 -47.3 -53.1 240 49 25 -0.5 -0.3 M M M M M 36000 -47.6 -53.7 245 43 22 -0.5 -0.3 M M M M M 34000 -47.7 -53.9 255 38 20 2.7 1.5 M M M M M 32000 -45.9 -50.6 255 35 18 2.6 1.5 M M M M M 30000 -43.7 -46.7 255 32 16 7.4 4.1 31.9 89.5 11.9 M M 29000 -41.5 -42.7 255 30 15 7.4 4.1 30.9 87.6 11.3 M M 28000 -39.3 -38.7 255 27 14 7.4 4.1 30.0 86.0 10.7 M M 27000 -37.1 -34.8 255 25 13 7.8 4.3 29.3 84.7 10.2 M M 26000 -34.6 -30.3 260 26 13 8.4 4.6 28.6 83.5 9.8 M M 25000 -32.1 -25.8 260 27 14 8.4 4.6 28.1 82.6 9.5 M M 24000 -29.6 -21.3 265 28 14 8.4 4.6 27.7 81.9 9.3 M M 23000 -27.1 -16.8 265 28 15 8.0 4.4 27.0 80.6 8.9 M M 22000 -24.8 -12.6 265 29 15 8.0 4.4 26.4 79.5 8.4 M M 21000 -22.4 -8.3 265 29 15 7.6 4.2 25.9 78.6 8.1 M M 20000 -20.3 -4.5 270 29 15 6.9 3.8 24.8 76.6 7.2 M M 19500 -19.3 -2.7 270 29 15 6.9 3.8 24.3 75.7 6.8 M M 19000 -18.3 -0.9 275 29 15 6.9 3.8 23.8 74.9 6.4 M M 18500 -17.3 0.9 275 29 15 6.9 3.8 23.4 74.1 6.1 M M 18000 -16.3 2.7 280 29 15 6.5 3.5 22.8 73.1 5.6 M M 17500 -14.9 5.2 280 30 15 6.5 3.6 22.0 71.6 4.9 M M 17000 -13.9 7.0 280 31 16 6.7 3.7 21.5 70.7 4.4 M M 16500 -12.9 8.8 285 31 16 6.7 3.7 21.0 69.7 4.0 M M 16000 -11.9 10.6 285 32 16 7.2 4.0 20.5 68.9 3.6 M M 15500 -10.8 12.6 285 32 17 7.3 4.0 20.1 68.1 3.2 M M 15000 -9.7 14.5 290 32 17 7.2 3.9 19.7 67.4 2.9 M M 14500 -8.7 16.3 290 32 16 7.2 3.9 19.2 66.6 2.4 M M 14000 -7.6 18.3 290 32 16 7.2 4.0 18.8 65.8 2.1 M M 13500 -6.5 20.3 290 31 16 7.4 4.1 18.4 65.1 1.7 M M 13000 -5.5 22.1 295 30 16 7.3 4.0 18.0 64.4 1.3 M M 12500 -4.4 24.1 295 29 15 7.1 3.9 17.6 63.7 0.9 M M 12000 -3.4 25.9 295 28 15 7.1 3.9 17.2 62.9 0.4 M M 11500 -2.4 27.7 295 27 14 6.9 3.8 16.7 62.1 -0.0 451 2.3 11000 -1.4 29.5 295 25 13 6.7 3.7 16.3 61.3 -0.5 407 2.1 10500 -0.6 30.9 300 23 12 5.2 2.9 15.6 60.1 -1.1 367 1.9 10250 -0.2 31.6 300 22 11 5.6 3.1 15.3 59.5 -1.5 348 1.8 10000 0.2 32.4 300 21 11 6.9 3.8 15.0 59.0 -1.7 328 1.7 9750 0.7 33.3 305 19 10 5.2 2.9 14.8 58.6 -2.0 306 1.6 9500 1.0 33.8 305 18 9 3.3 1.8 14.3 57.7 -2.5 291 1.5 9250 1.2 34.2 310 16 8 4.2 2.3 13.8 56.9 -3.0 276 1.4 9000 1.5 34.7 310 15 8 2.6 1.5 13.4 56.1 -3.4 261 1.3 8750 1.6 34.9 315 13 7 1.1 0.6 12.7 54.9 -4.1 251 1.3 8500 1.7 35.1 315 12 6 1.5 0.8 12.1 53.7 -4.8 241 1.2 8250 1.7 35.1 320 11 5 1.2 0.7 11.4 52.6 -5.4 231 1.2 8000 1.8 35.2 325 9 5 2.8 1.6 10.8 51.5 -6.1 221 1.1 7750 2.1 35.8 330 8 4 4.5 2.5 10.4 50.7 -6.5 205 1.0 7500 2.4 36.3 335 7 3 4.4 2.4 10.0 49.9 -7.0 188 1.0 7250 2.7 36.9 335 5 3 4.5 2.5 9.6 49.2 -7.4 171 0.9 7000 3.1 37.6 345 4 2 4.3 2.4 9.2 48.5 -7.8 154 0.8 6750 3.4 38.1 355 4 2 5.4 2.9 8.8 47.8 -8.2 137 0.7 6500 3.8 38.8 360 3 1 6.2 3.4 8.5 47.3 -8.5 117 0.6 6250 4.3 39.7 005 2 1 6.7 3.7 8.2 46.8 -8.8 96 0.5 6000 4.8 40.6 350 1 1 7.0 3.8 8.0 46.4 -9.1 73 0.4 5750 5.3 41.5 305 1 0 7.9 4.3 7.8 46.1 -9.3 50 0.3 5500 6.0 42.8 320 1 0 11.1 6.1 7.8 46.0 -9.4 22 0.1 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 05/21/2024 at 0900 MDT | 05/21/2024 at 1200 MDT | CAPE... +46.7 LI... +2.5 | CAPE... +109.9 LI... -0.1 CINH... -4.0 K Index... +11.0 | CINH... -5.9 K Index... +22.4 | 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 -51.3 -60.3 235 42 22 2.8 1.5 | -51.0 -59.8 235 41 21 2.6 1.4 45000 -47.4 -53.3 235 49 25 -0.2 -0.1 | -47.3 -53.1 235 52 27 -0.5 -0.3 40000 -47.7 -53.9 240 56 29 -0.2 -0.1 | -48.6 -55.5 240 58 30 -0.9 -0.5 38000 -48.2 -54.8 240 56 29 -1.3 -0.7 | -48.8 -55.8 240 61 31 0.3 0.2 36000 -49.0 -56.2 245 54 28 -1.3 -0.7 | -48.6 -55.5 240 65 34 0.3 0.2 34000 -49.4 -56.9 250 51 26 3.6 2.0 | -48.2 -54.8 245 69 35 3.1 1.7 32000 -47.4 -53.3 250 48 25 3.4 1.9 | -46.4 -51.5 245 70 36 3.0 1.6 30000 -44.4 -47.9 250 44 23 8.3 4.5 | -43.9 -47.0 245 68 35 6.8 3.7 29000 -41.9 -43.4 250 41 21 8.3 4.6 | -41.9 -43.4 245 64 33 6.8 3.7 28000 -39.4 -38.9 245 39 20 8.4 4.6 | -39.9 -39.8 240 60 31 6.8 3.7 27000 -36.9 -34.4 245 37 19 8.2 4.5 | -37.9 -36.2 240 55 28 7.3 4.0 26000 -34.5 -30.1 245 36 19 8.1 4.4 | -35.5 -31.9 240 52 27 8.1 4.5 25000 -32.1 -25.8 245 36 18 8.1 4.4 | -33.1 -27.6 240 49 25 8.1 4.5 24000 -29.7 -21.5 245 35 18 8.1 4.4 | -30.6 -23.1 240 46 24 8.1 4.4 23000 -27.2 -17.0 245 36 18 8.2 4.5 | -28.3 -18.9 240 44 23 7.8 4.3 22000 -24.8 -12.6 245 36 19 8.2 4.5 | -26.0 -14.8 240 43 22 7.8 4.3 21000 -22.3 -8.1 250 37 19 8.0 4.4 | -23.7 -10.7 240 41 21 7.6 4.2 20000 -20.0 -4.0 250 37 19 7.8 4.3 | -21.5 -6.7 240 39 20 7.5 4.1 19500 -18.9 -2.0 255 37 19 7.8 4.3 | -20.4 -4.7 240 39 20 7.5 4.1 19000 -17.7 0.1 255 37 19 7.8 4.3 | -19.3 -2.7 245 38 19 7.5 4.1 18500 -16.5 2.3 255 37 19 7.6 4.2 | -18.2 -0.8 245 37 19 7.5 4.1 18000 -15.5 4.1 260 37 19 6.8 3.7 | -17.1 1.2 245 36 18 7.4 4.1 17500 -14.5 5.9 265 37 19 6.9 3.8 | -16.0 3.2 245 35 18 7.4 4.1 17000 -13.5 7.7 265 38 19 6.1 3.4 | -14.9 5.2 245 33 17 7.2 4.0 16500 -12.1 10.2 270 37 19 6.2 3.4 | -13.9 7.0 245 32 17 7.2 4.0 16000 -11.3 11.7 275 37 19 5.1 2.8 | -12.8 9.0 245 31 16 7.0 3.8 15500 -10.6 12.9 275 36 18 5.1 2.8 | -11.3 11.7 250 30 16 6.7 3.7 15000 -9.8 14.4 280 35 18 5.2 2.8 | -10.3 13.5 255 30 15 6.8 3.7 14500 -9.1 15.6 280 33 17 5.2 2.9 | -9.3 15.3 255 29 15 6.8 3.8 14000 -8.3 17.1 280 31 16 5.6 3.1 | -8.3 17.1 260 28 14 7.0 3.8 13500 -7.5 18.5 285 29 15 6.1 3.3 | -7.3 18.9 260 26 13 7.1 3.9 13000 -6.6 20.1 285 28 14 6.3 3.5 | -6.3 20.7 265 23 12 7.2 4.0 12500 -5.6 21.9 285 26 13 6.9 3.8 | -5.2 22.6 265 21 11 7.5 4.1 12000 -4.6 23.7 290 25 13 7.0 3.8 | -4.1 24.6 270 19 10 7.2 3.9 11500 -3.6 25.5 290 23 12 7.4 4.1 | -3.1 26.4 275 16 8 6.3 3.5 11000 -2.5 27.5 295 22 11 7.1 3.9 | -2.2 28.0 280 13 7 6.2 3.4 10500 -1.5 29.3 295 21 11 5.8 3.2 | -1.4 29.5 290 11 6 5.4 2.9 10250 -1.1 30.0 295 20 10 7.4 4.1 | -0.9 30.4 295 10 5 7.9 4.3 10000 -0.4 31.3 300 19 10 10.8 5.9 | -0.2 31.6 300 9 5 10.9 6.0 9750 0.4 32.7 300 18 9 8.9 4.9 | 0.5 32.9 305 8 4 9.4 5.1 9500 0.9 33.6 300 17 9 6.3 3.4 | 1.2 34.2 310 7 4 8.7 4.8 9250 1.4 34.5 305 16 8 7.8 4.3 | 1.8 35.2 320 6 3 8.7 4.8 9000 1.9 35.4 305 15 8 4.5 2.5 | 2.4 36.3 325 6 3 7.6 4.2 8750 2.0 35.6 305 15 7 3.3 1.8 | 3.0 37.4 335 6 3 9.0 4.9 8500 2.4 36.3 310 13 7 5.4 2.9 | 3.8 38.8 335 6 3 10.6 5.8 8250 2.7 36.9 310 12 6 4.9 2.7 | 4.5 40.1 340 6 3 9.6 5.3 8000 3.1 37.6 315 11 6 5.8 3.2 | 5.2 41.4 345 6 3 8.5 4.7 7750 3.5 38.3 315 10 5 5.6 3.1 | 5.8 42.4 350 6 3 9.8 5.4 7500 3.9 39.0 315 8 4 5.4 3.0 | 6.6 43.9 355 6 3 11.6 6.4 7250 4.2 39.6 320 6 3 4.6 2.5 | 7.4 45.3 355 6 3 9.4 5.1 7000 4.4 39.9 325 4 2 2.2 1.2 | 8.0 46.4 360 6 3 6.8 3.7 6750 4.6 40.3 330 3 1 6.6 3.6 | 8.6 47.5 360 6 3 10.6 5.8 6500 5.3 41.5 345 2 1 10.4 5.7 | 9.6 49.3 005 6 3 13.2 7.3 6250 6.0 42.8 020 1 1 8.9 4.9 | 10.5 50.9 005 6 3 10.5 5.8 6000 6.7 44.1 045 1 1 8.4 4.6 | 11.2 52.2 005 6 3 9.4 5.2 5750 7.3 45.1 060 1 1 9.9 5.4 | 11.9 53.4 010 6 3 10.1 5.6 5500 8.2 46.8 040 1 0 16.7 9.2 | 12.9 55.2 005 5 3 17.8 9.8 05/21/2024 at 1500 MDT | 05/21/2024 at 1800 MDT | CAPE... +179.2 LI... -0.4 | CAPE... +165.8 LI... -0.1 CINH... -33.5 K Index... +27.0 | CINH... -15.1 K Index... +25.0 | 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 -50.8 -59.4 240 42 21 2.1 1.1 | -50.0 -58.0 235 38 20 1.4 0.8 45000 -47.8 -54.0 235 55 28 -0.1 -0.1 | -48.1 -54.6 245 54 28 -0.6 -0.3 40000 -47.8 -54.0 245 66 34 -0.0 -0.0 | -49.6 -57.3 255 68 35 -1.0 -0.5 38000 -48.2 -54.8 250 71 36 -1.2 -0.7 | -49.8 -57.6 255 73 38 0.2 0.1 36000 -49.0 -56.2 250 76 39 -1.2 -0.7 | -49.7 -57.5 250 78 40 0.2 0.1 34000 -49.5 -57.1 245 80 41 2.3 1.3 | -49.3 -56.7 245 81 42 4.4 2.4 32000 -48.0 -54.4 245 73 37 2.6 1.4 | -46.9 -52.4 245 80 41 4.1 2.2 30000 -45.6 -50.1 240 64 33 7.3 4.0 | -43.8 -46.8 245 76 39 6.7 3.7 29000 -43.4 -46.1 240 59 30 7.3 4.0 | -41.8 -43.2 245 73 38 6.8 3.7 28000 -41.3 -42.3 235 54 28 7.3 4.0 | -39.8 -39.6 240 70 36 6.8 3.7 27000 -39.1 -38.4 235 50 26 7.9 4.3 | -37.7 -35.9 240 67 35 6.8 3.7 26000 -36.4 -33.5 235 47 24 8.9 4.9 | -35.7 -32.3 235 61 32 6.9 3.8 25000 -33.8 -28.8 235 45 23 8.9 4.9 | -33.6 -28.5 230 56 29 6.9 3.8 24000 -31.1 -24.0 235 42 22 8.9 4.9 | -31.6 -24.9 225 51 26 7.1 3.9 23000 -28.6 -19.5 235 41 21 8.3 4.6 | -29.3 -20.7 225 48 25 8.0 4.4 22000 -26.2 -15.2 235 40 21 8.3 4.6 | -26.9 -16.4 225 46 24 8.0 4.4 21000 -23.7 -10.7 235 39 20 8.1 4.5 | -24.5 -12.1 225 44 23 8.1 4.5 20000 -21.3 -6.3 235 38 20 8.0 4.4 | -22.1 -7.8 230 41 21 8.3 4.5 19500 -20.2 -4.4 240 38 19 8.0 4.4 | -20.9 -5.6 230 40 21 8.3 4.5 19000 -19.0 -2.2 240 37 19 8.0 4.4 | -19.7 -3.5 230 39 20 8.3 4.5 18500 -17.8 -0.0 240 37 19 7.9 4.3 | -18.5 -1.3 230 38 19 8.1 4.4 18000 -16.7 1.9 240 36 18 7.7 4.2 | -17.3 0.9 230 36 18 7.7 4.2 17500 -15.6 3.9 235 35 18 7.7 4.2 | -16.2 2.8 235 34 17 7.7 4.2 17000 -13.9 7.0 235 33 17 7.5 4.1 | -15.1 4.8 235 32 16 7.1 3.9 16500 -12.8 9.0 235 32 17 7.5 4.1 | -14.1 6.6 235 30 15 7.1 3.9 16000 -11.8 10.8 235 31 16 7.3 4.0 | -12.5 9.5 240 28 14 6.7 3.7 15500 -10.7 12.7 235 29 15 7.3 4.0 | -11.6 11.1 245 27 14 6.7 3.7 15000 -9.7 14.5 235 28 14 6.9 3.8 | -10.6 12.9 250 26 13 6.6 3.6 14500 -8.7 16.3 235 25 13 6.8 3.7 | -9.6 14.7 255 24 13 6.5 3.6 14000 -7.7 18.1 235 23 12 6.7 3.7 | -8.7 16.3 260 23 12 6.7 3.7 13500 -6.7 19.9 235 21 11 6.7 3.7 | -7.7 18.1 265 22 11 6.7 3.7 13000 -5.7 21.7 235 19 10 6.7 3.7 | -6.7 19.9 270 21 11 6.8 3.8 12500 -4.8 23.4 230 16 8 6.7 3.7 | -5.7 21.7 270 20 10 7.0 3.8 12000 -3.8 25.2 230 14 7 6.6 3.6 | -4.7 23.5 275 20 10 7.1 3.9 11500 -2.9 26.8 230 12 6 6.4 3.5 | -3.6 25.5 280 18 9 7.2 4.0 11000 -1.9 28.6 230 9 5 6.1 3.3 | -2.6 27.3 285 17 9 6.7 3.7 10500 -1.1 30.0 230 7 4 4.9 2.7 | -1.6 29.1 285 16 8 5.3 2.9 10250 -0.8 30.6 235 6 3 6.2 3.4 | -1.2 29.8 290 16 8 9.3 5.1 10000 -0.2 31.6 240 5 3 7.7 4.2 | -0.3 31.5 290 15 8 10.6 5.8 9750 0.3 32.5 245 5 2 6.5 3.5 | 0.3 32.5 290 15 8 7.5 4.1 9500 0.7 33.3 250 4 2 5.7 3.1 | 0.9 33.6 295 14 7 8.5 4.7 9250 1.1 34.0 260 4 2 5.9 3.3 | 1.5 34.7 295 14 7 7.8 4.3 9000 1.5 34.7 270 3 2 5.4 3.0 | 2.0 35.6 295 13 7 7.2 4.0 8750 2.0 35.6 280 3 1 6.5 3.6 | 2.6 36.7 295 12 6 7.8 4.3 8500 2.5 36.5 290 3 1 7.7 4.2 | 3.1 37.6 295 11 6 8.4 4.6 8250 3.0 37.4 305 3 2 7.3 4.0 | 3.7 38.7 295 11 5 7.5 4.1 8000 3.6 38.5 315 3 2 7.4 4.1 | 4.2 39.6 295 9 5 6.2 3.4 7750 4.1 39.4 320 3 1 8.3 4.5 | 4.7 40.5 295 8 4 6.8 3.7 7500 4.8 40.6 325 3 2 9.0 5.0 | 5.2 41.4 295 7 4 7.7 4.2 7250 5.4 41.7 325 4 2 8.0 4.4 | 5.7 42.3 290 6 3 6.7 3.7 7000 5.9 42.6 330 3 2 6.5 3.6 | 6.2 43.2 295 4 2 5.7 3.1 6750 6.5 43.7 335 3 1 9.6 5.3 | 6.6 43.9 295 3 2 7.8 4.3 6500 7.3 45.1 330 3 2 11.9 6.5 | 7.3 45.1 295 2 1 9.5 5.2 6250 8.1 46.6 330 4 2 9.7 5.3 | 7.9 46.2 295 1 1 9.1 5.0 6000 8.8 47.8 335 3 1 8.9 4.9 | 8.6 47.5 000 0 0 9.3 5.1 5750 9.5 49.1 340 2 1 9.6 5.3 | 9.3 48.7 070 1 0 9.3 5.1 5500 10.3 50.5 325 4 2 14.1 7.8 | 10.0 50.0 000 0 0 11.9 6.6 ________________________________________________________________________________ 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