Issued by NWS Denver/Boulder, CO
000 UXUS97 KBOU 101323 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 723 AM MDT Sunday May 10, 2009 This forecast is for Sunday May 10, 2009: If the trigger temperature of 53.3 F/11.8 C is reached...then Thermal Soaring Index....................... Poor Maximum rate of lift........................ 21 ft/min (0.1 m/s) Maximum height of thermals.................. 11377 ft MSL (6092 ft AGL) Forecast maximum temperature................... 60.0 F/16.0 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................. 9700 ft MSL (4415 ft AGL) Thermal soaring outlook for Monday 05/11....... Excellent Wave Soaring Index............................. Poor Wave Soaring Index trend (to 1800 MDT)......... Little change Height of stable layer (12-18K ft MSL)......... None Weak PVA/NVA (through 1800 MDT)................ Weak NVA Potential height of wave....................... 18809 ft MSL (13524 ft AGL) Wave soaring outlook for Monday 05/11.......... Fair Remarks... Sunrise/Sunset.................... 05:49:36 / 20:01:56 MDT Total possible sunshine........... 14 hr 12 min 20 sec (852 min 20 sec) Altitude of sun at 12:55:58 MDT... 68.02 degrees Upper air data from rawinsonde observation taken on 05/10/2009 at 0600 MDT Freezing level.................. 9226 ft MSL (3941 ft AGL) Convective condensation level... 9540 ft MSL (4255 ft AGL) Lifted condensation level....... 10919 ft MSL (5633 ft AGL) Lifted index.................... +1.5 K index......................... +21.2 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 -59.0 -74.2 284 57 29 4.1 2.2 102.4 216.4 49.5 M M 45000 -57.5 -71.5 270 78 40 -1.0 -0.5 79.5 175.1 39.1 M M 40000 -59.0 -74.2 260 72 37 -2.6 -1.4 52.8 127.1 24.5 M M 38000 -60.6 -77.1 270 81 42 -9.0 -4.9 41.7 107.1 17.7 M M 36000 -57.9 -72.2 268 90 46 7.3 4.0 36.9 98.4 14.8 M M 34000 -52.7 -62.9 265 83 43 9.6 5.2 36.0 96.8 14.6 M M 32000 -46.9 -52.4 268 81 42 9.7 5.3 35.9 96.6 14.9 M M 30000 -42.1 -43.8 270 77 39 8.1 4.4 34.6 94.3 14.3 M M 29000 -39.1 -38.4 270 71 37 8.1 4.4 33.7 92.7 13.9 M M 28000 -36.8 -34.2 270 67 35 7.4 4.1 32.9 91.3 13.4 M M 27000 -34.6 -30.3 270 63 32 7.2 4.0 32.1 89.7 12.9 M M 26000 -32.5 -26.5 269 59 30 7.0 3.8 31.0 87.8 12.2 M M 25000 -30.0 -22.0 265 60 31 8.9 4.9 30.5 87.0 12.0 M M 24000 -27.5 -17.5 263 59 30 6.0 3.3 30.0 86.0 11.7 M M 23000 -25.4 -13.7 255 59 30 8.0 4.4 28.9 84.0 10.9 M M 22000 -22.8 -9.0 257 56 29 8.7 4.7 28.5 83.2 10.7 M M 21000 -20.3 -4.5 261 53 27 4.1 2.3 28.1 82.5 10.5 M M 20000 -19.2 -2.6 264 50 26 6.8 3.8 25.9 78.7 8.7 M M 19500 -18.2 -0.8 265 52 27 8.0 4.4 25.5 77.9 8.3 M M 19000 -16.9 1.6 265 54 28 8.7 4.8 25.3 77.5 8.2 M M 18500 -15.7 3.7 265 55 28 7.9 4.3 25.0 77.1 8.0 M M 18000 -14.6 5.7 266 54 28 7.9 4.3 24.7 76.4 7.7 M M 17500 -13.4 7.9 268 53 27 7.9 4.3 24.4 75.9 7.4 M M 17000 -12.3 9.9 269 52 27 8.2 4.5 24.1 75.3 7.2 M M 16500 -11.3 11.7 271 50 25 5.0 2.7 23.6 74.4 6.7 M M 16000 -10.6 12.9 274 47 24 5.2 2.8 22.7 72.9 6.0 M M 15500 -9.8 14.4 275 43 22 6.1 3.3 22.1 71.7 5.4 M M 15000 -8.9 16.0 276 40 21 6.0 3.3 21.4 70.6 4.8 M M 14500 -7.5 18.5 278 35 18 6.1 3.3 20.5 68.9 4.0 M M 14000 -6.6 20.1 279 31 16 6.2 3.4 20.0 67.9 3.5 M M 13500 -5.8 21.6 274 20 10 6.3 3.4 19.4 66.9 2.9 M M 13000 -4.9 23.2 265 11 6 6.0 3.3 18.8 65.9 2.4 M M 12500 -4.2 24.4 272 7 4 4.7 2.6 18.1 64.5 1.6 M M 12000 -3.5 25.7 289 4 2 4.8 2.6 17.3 63.1 0.9 M M 11500 -2.8 27.0 286 4 2 5.2 2.8 16.5 61.6 0.1 M M 11000 -2.5 27.5 282 3 2 -2.2 -1.2 15.3 59.6 -1.0 399 2.0 10500 -2.1 28.2 278 3 2 7.5 4.1 14.2 57.5 -2.1 373 1.9 10250 -1.6 29.1 275 3 2 5.8 3.2 13.9 57.0 -2.4 352 1.8 10000 -1.2 29.8 284 3 1 5.8 3.2 13.6 56.5 -2.7 332 1.7 9750 -0.8 30.6 301 2 1 5.5 3.0 13.3 55.9 -3.0 312 1.6 9500 -0.4 31.3 320 2 1 5.9 3.3 12.9 55.3 -3.3 292 1.5 9250 0.0 32.0 337 3 1 3.3 1.8 12.6 54.7 -3.6 273 1.4 9000 0.1 32.2 349 3 2 1.0 0.5 12.0 53.5 -4.3 263 1.3 8750 0.2 32.4 348 3 2 1.6 0.9 11.3 52.4 -4.9 253 1.3 8500 0.3 32.5 347 4 2 1.3 0.7 10.7 51.2 -5.6 242 1.2 8250 0.5 32.9 345 4 2 4.3 2.3 10.1 50.2 -6.1 230 1.2 8000 0.9 33.6 344 4 2 6.5 3.6 9.8 49.7 -6.4 210 1.1 7750 1.4 34.5 337 4 2 5.9 3.2 9.5 49.2 -6.8 189 1.0 7500 1.8 35.2 329 4 2 6.1 3.4 9.2 48.6 -7.1 168 0.9 7250 2.2 36.0 322 4 2 5.9 3.2 9.0 48.1 -7.4 148 0.8 7000 2.7 36.9 315 4 2 6.6 3.6 8.7 47.6 -7.7 127 0.6 6750 3.2 37.8 319 4 2 7.6 4.2 8.5 47.3 -7.9 104 0.5 6500 3.7 38.7 323 5 3 7.8 4.3 8.3 47.0 -8.1 80 0.4 6250 4.3 39.7 327 5 3 7.7 4.2 8.2 46.8 -8.3 56 0.3 6000 4.8 40.6 329 6 3 7.9 4.3 8.1 46.5 -8.5 32 0.2 5750 5.4 41.7 335 6 3 7.3 4.0 7.9 46.2 -8.7 8 0.0 5500 6.0 42.8 340 7 3 9.6 5.3 7.8 46.0 -8.9 M M * * * * * * Numerical weather prediction model forecast data valid * * * * * * 05/10/2009 at 0900 MDT | 05/10/2009 at 1200 MDT | K index... +22.7 | K index... +18.5 | 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 -57.9 -72.2 278 54 28 0.3 0.2 | -58.6 -73.5 284 61 31 -0.4 -0.2 45000 -57.5 -71.5 279 66 34 -1.3 -0.7 | -59.1 -74.4 286 73 38 -0.2 -0.1 40000 -59.4 -74.9 276 68 35 -1.3 -0.7 | -59.5 -75.1 289 79 41 -0.2 -0.1 38000 -57.9 -72.2 274 70 36 4.9 2.7 | -57.5 -71.5 289 80 41 5.2 2.9 36000 -54.9 -66.8 271 73 37 4.9 2.7 | -54.4 -65.9 289 81 41 5.2 2.9 34000 -50.9 -59.6 270 75 38 8.1 4.4 | -50.1 -58.2 287 82 42 8.1 4.5 32000 -46.0 -50.8 272 74 38 8.1 4.4 | -45.3 -49.5 285 83 43 8.1 4.5 30000 -41.3 -42.3 272 71 36 7.7 4.2 | -40.6 -41.1 284 80 41 7.3 4.0 29000 -39.0 -38.2 273 68 35 7.7 4.2 | -38.4 -37.1 284 75 38 7.3 4.0 28000 -36.7 -34.1 273 65 33 7.7 4.2 | -36.2 -33.2 283 69 36 7.3 4.0 27000 -34.4 -29.9 273 62 32 6.3 3.5 | -33.9 -29.0 283 65 34 8.5 4.7 26000 -32.5 -26.5 275 59 30 6.5 3.5 | -31.4 -24.5 283 63 32 8.4 4.6 25000 -30.6 -23.1 276 55 28 6.5 3.6 | -28.9 -20.0 282 60 31 8.4 4.6 24000 -28.6 -19.5 277 52 27 7.3 4.0 | -26.4 -15.5 282 58 30 6.9 3.8 23000 -26.3 -15.3 278 50 26 7.7 4.2 | -24.5 -12.1 280 57 29 6.6 3.6 22000 -24.1 -11.4 279 49 25 7.7 4.2 | -22.5 -8.5 277 57 29 6.7 3.7 21000 -21.7 -7.1 279 47 24 8.4 4.6 | -20.6 -5.1 275 56 29 6.0 3.3 20000 -19.3 -2.7 279 48 25 8.4 4.6 | -18.8 -1.8 274 54 28 6.1 3.4 19500 -18.0 -0.4 279 48 25 8.4 4.6 | -17.9 -0.2 273 53 27 6.2 3.4 19000 -16.8 1.8 278 49 25 8.4 4.6 | -17.0 1.4 273 53 27 6.2 3.4 18500 -15.6 3.9 278 48 25 8.2 4.5 | -15.5 4.1 272 50 26 7.1 3.9 18000 -13.8 7.2 277 46 24 8.3 4.5 | -14.4 6.1 273 48 25 7.1 3.9 17500 -12.7 9.1 277 44 23 6.9 3.8 | -13.4 7.9 273 45 23 7.9 4.3 17000 -11.7 10.9 277 42 21 6.8 3.7 | -12.2 10.0 273 42 22 7.9 4.3 16500 -10.7 12.7 277 40 20 6.6 3.6 | -11.0 12.2 273 40 20 7.8 4.3 16000 -9.8 14.4 277 38 19 6.3 3.4 | -9.9 14.2 274 38 19 7.7 4.2 15500 -8.8 16.2 277 36 18 6.3 3.5 | -8.8 16.2 274 36 18 7.7 4.2 15000 -7.9 17.8 278 34 17 6.9 3.8 | -7.7 18.1 275 34 17 7.4 4.1 14500 -6.9 19.6 279 32 16 7.0 3.8 | -6.6 20.1 276 31 16 7.5 4.1 14000 -5.9 21.4 280 30 15 6.1 3.3 | -5.5 22.1 277 29 15 7.1 3.9 13500 -5.0 23.0 282 27 14 6.2 3.4 | -4.5 23.9 278 27 14 7.3 4.0 13000 -4.2 24.4 284 24 12 4.8 2.6 | -3.5 25.7 280 24 12 6.0 3.3 12500 -3.6 25.5 286 22 11 4.8 2.6 | -2.6 27.3 281 21 11 6.1 3.3 12000 -3.0 26.6 289 19 10 2.2 1.2 | -1.9 28.6 284 19 10 3.2 1.8 11500 -2.8 27.0 291 17 9 1.7 0.9 | -1.6 29.1 286 16 8 3.0 1.7 11000 -2.5 27.5 293 14 7 2.4 1.3 | -1.3 29.7 288 13 7 0.9 0.5 10500 -2.2 28.0 295 11 6 2.4 1.3 | -1.3 29.7 291 10 5 0.3 0.2 10250 -2.0 28.4 297 10 5 3.1 1.7 | -1.2 29.8 293 8 4 1.7 0.9 10000 -1.7 28.9 302 9 4 4.3 2.3 | -1.0 30.2 293 7 4 3.8 2.1 9750 -1.4 29.5 309 8 4 4.4 2.4 | -0.7 30.7 292 6 3 4.1 2.2 9500 -1.1 30.0 318 7 4 4.4 2.4 | -0.4 31.3 291 5 2 3.9 2.1 9250 -0.8 30.6 328 7 3 4.3 2.4 | -0.1 31.8 289 3 2 4.5 2.5 9000 -0.4 31.3 333 7 4 4.2 2.3 | 0.2 32.4 289 3 1 5.1 2.8 8750 -0.1 31.8 336 7 4 4.2 2.3 | 0.6 33.1 289 2 1 5.0 2.7 8500 0.2 32.4 339 7 4 4.2 2.3 | 1.0 33.8 289 1 0 5.0 2.8 8250 0.5 32.9 343 8 4 4.3 2.4 | 1.3 34.3 000 0 0 5.0 2.7 8000 0.8 33.4 347 8 4 4.4 2.4 | 1.7 35.1 000 0 0 5.1 2.8 7750 1.1 34.0 350 8 4 4.4 2.4 | 2.0 35.6 000 0 0 4.6 2.5 7500 1.4 34.5 354 8 4 4.4 2.4 | 2.4 36.3 028 1 0 6.2 3.4 7250 1.7 35.1 359 9 5 4.5 2.5 | 2.9 37.2 025 1 0 8.3 4.6 7000 2.1 35.8 005 10 5 4.3 2.3 | 3.5 38.3 021 1 1 8.1 4.5 6750 2.4 36.3 009 10 5 5.0 2.7 | 4.1 39.4 018 1 1 8.5 4.7 6500 2.8 37.0 011 11 5 8.2 4.5 | 4.8 40.6 015 1 1 10.0 5.5 6250 3.5 38.3 009 10 5 10.0 5.5 | 5.6 42.1 011 1 1 11.1 6.1 6000 4.2 39.6 007 10 5 9.0 5.0 | 6.4 43.5 007 1 1 9.9 5.4 5750 4.9 40.8 005 9 5 12.3 6.8 | 7.2 45.0 003 1 1 14.8 8.1 5500 6.1 43.0 006 8 4 19.0 10.4 | 8.7 47.7 001 1 1 25.8 14.2 05/10/2009 at 1500 MDT | 05/10/2009 at 1800 MDT | K index... +23.2 | K index... +23.9 | 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 -59.9 -75.8 288 58 30 -0.3 -0.1 | -61.2 -78.2 288 56 29 -0.2 -0.1 45000 -60.1 -76.2 292 77 40 0.8 0.4 | -61.3 -78.3 293 76 39 1.3 0.7 40000 -59.1 -74.4 295 96 49 0.7 0.4 | -59.5 -75.1 292 93 48 1.3 0.7 38000 -56.5 -69.7 296 99 51 6.1 3.4 | -56.4 -69.5 292 94 48 6.9 3.8 36000 -52.9 -63.2 295 99 51 6.1 3.4 | -51.7 -61.1 292 92 47 6.9 3.8 34000 -48.4 -55.1 294 97 50 7.4 4.0 | -47.4 -53.3 291 90 46 7.7 4.2 32000 -44.0 -47.2 289 93 48 7.4 4.0 | -42.7 -44.9 288 86 44 7.7 4.2 30000 -39.9 -39.8 287 86 44 6.1 3.4 | -38.2 -36.8 287 83 43 7.5 4.1 29000 -38.0 -36.4 286 81 42 6.1 3.4 | -35.9 -32.6 288 80 41 7.5 4.1 28000 -36.2 -33.2 286 76 39 6.1 3.4 | -33.7 -28.7 290 78 40 7.5 4.1 27000 -34.2 -29.6 286 71 37 8.0 4.4 | -31.5 -24.7 290 76 39 6.2 3.4 26000 -31.9 -25.4 284 67 35 7.8 4.3 | -29.7 -21.5 289 72 37 6.3 3.5 25000 -29.5 -21.1 283 64 33 7.8 4.3 | -27.8 -18.0 288 67 35 6.3 3.5 24000 -27.2 -17.0 281 60 31 7.4 4.1 | -25.9 -14.6 286 64 33 6.4 3.5 23000 -25.0 -13.0 280 58 30 7.3 4.0 | -24.0 -11.2 283 61 31 6.4 3.5 22000 -22.8 -9.0 279 55 28 7.3 4.0 | -22.1 -7.8 279 58 30 6.4 3.5 21000 -20.6 -5.1 277 54 28 7.4 4.0 | -20.1 -4.2 277 56 29 7.5 4.1 20000 -18.4 -1.1 273 54 28 7.4 4.1 | -17.9 -0.2 277 54 28 7.4 4.1 19500 -17.3 0.9 271 54 28 7.4 4.1 | -16.2 2.8 277 53 27 7.4 4.1 19000 -16.2 2.8 269 54 28 7.5 4.1 | -15.1 4.8 277 52 27 7.2 4.0 18500 -14.7 5.5 266 52 27 6.9 3.8 | -14.1 6.6 274 50 26 6.8 3.7 18000 -13.7 7.3 263 49 25 6.9 3.8 | -13.1 8.4 271 48 24 6.9 3.8 17500 -12.7 9.1 261 47 24 8.0 4.4 | -12.1 10.2 268 45 23 8.2 4.5 17000 -11.5 11.3 260 44 23 8.1 4.4 | -10.9 12.4 267 43 22 8.2 4.5 16500 -10.3 13.5 259 41 21 7.6 4.2 | -9.7 14.5 266 40 21 7.4 4.1 16000 -9.3 15.3 260 38 19 7.1 3.9 | -8.8 16.2 267 37 19 6.6 3.6 15500 -8.3 17.1 260 35 18 6.8 3.7 | -7.9 17.8 267 35 18 6.4 3.5 15000 -7.5 18.5 260 31 16 4.8 2.6 | -7.1 19.2 267 32 16 4.9 2.7 14500 -6.8 19.8 259 27 14 5.0 2.7 | -6.4 20.5 266 29 15 5.0 2.7 14000 -6.1 21.0 258 24 12 4.2 2.3 | -5.7 21.7 264 26 13 5.1 2.8 13500 -5.5 22.1 256 20 10 4.2 2.3 | -4.9 23.2 261 23 12 5.1 2.8 13000 -4.9 23.2 254 16 8 5.1 2.8 | -4.2 24.4 257 20 10 5.1 2.8 12500 -4.1 24.6 249 12 6 5.1 2.8 | -3.5 25.7 251 18 9 5.1 2.8 12000 -3.3 26.1 242 9 5 5.6 3.1 | -2.7 27.1 245 15 8 4.8 2.6 11500 -2.5 27.5 229 6 3 5.6 3.1 | -2.0 28.4 238 12 6 4.7 2.6 11000 -1.6 29.1 206 5 3 6.1 3.3 | -1.3 29.7 228 8 4 5.1 2.8 10500 -0.7 30.7 182 5 3 6.2 3.4 | -0.6 30.9 208 4 2 5.1 2.8 10250 -0.3 31.5 172 5 3 6.1 3.4 | -0.2 31.6 179 3 2 5.1 2.8 10000 0.2 32.4 163 5 3 6.0 3.3 | 0.1 32.2 144 3 2 5.0 2.8 9750 0.6 33.1 154 5 2 6.1 3.3 | 0.5 32.9 120 4 2 5.1 2.8 9500 1.0 33.8 143 4 2 5.9 3.3 | 0.9 33.6 105 5 3 4.9 2.7 9250 1.5 34.7 132 4 2 6.6 3.6 | 1.2 34.2 097 6 3 5.6 3.1 9000 2.0 35.6 109 3 2 7.2 4.0 | 1.7 35.1 092 7 4 6.4 3.5 8750 2.5 36.5 080 3 2 7.0 3.9 | 2.1 35.8 088 8 4 6.1 3.4 8500 2.9 37.2 055 4 2 7.4 4.1 | 2.6 36.7 085 9 5 6.5 3.6 8250 3.5 38.3 043 5 3 9.2 5.1 | 3.1 37.6 083 10 5 8.5 4.7 8000 4.3 39.7 042 5 3 10.3 5.6 | 3.8 38.8 082 10 5 9.7 5.3 7750 5.0 41.0 040 5 3 10.0 5.5 | 4.5 40.1 081 11 6 9.3 5.1 7500 5.8 42.4 039 5 3 10.1 5.6 | 5.2 41.4 080 11 6 9.5 5.2 7250 6.5 43.7 038 5 3 10.2 5.6 | 5.9 42.6 080 11 6 9.6 5.3 7000 7.3 45.1 036 5 3 10.2 5.6 | 6.6 43.9 079 12 6 9.6 5.3 6750 8.0 46.4 035 5 3 10.2 5.6 | 7.3 45.1 078 12 6 9.6 5.3 6500 8.8 47.8 033 5 3 10.2 5.6 | 8.0 46.4 077 12 6 9.7 5.3 6250 9.6 49.3 031 5 3 10.7 5.9 | 8.8 47.8 077 12 6 9.9 5.5 6000 10.4 50.7 030 5 3 9.0 5.0 | 9.5 49.1 077 12 6 9.6 5.2 5750 11.1 52.0 028 5 2 15.2 8.3 | 10.2 50.4 077 11 6 10.9 6.0 5500 12.8 55.0 028 5 3 30.7 16.8 | 11.1 52.0 077 10 5 14.2 7.8 ________________________________________________________________________________ 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: 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 - 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, cirrostatus, 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. 071806