Issued by NWS Denver/Boulder, CO
000 UXUS97 KBOU 040027 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 627 PM MDT Sunday May 3, 2009 This forecast is for Monday May 4, 2009: If the trigger temperature of 63.0 F/17.2 C is reached...then Thermal Soaring Index....................... Fair Maximum rate of lift........................ 369 ft/min (1.9 m/s) Maximum height of thermals.................. 12288 ft MSL (6965 ft AGL) Forecast maximum temperature................... 67.0 F/19.9 C Time of trigger temperature.................... 1200 MDT Time of overdevelopment........................ None Middle/high clouds during soaring window....... Broken/overcast thin middle Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 8236 ft MSL (2913 ft AGL) Thermal soaring outlook for Tuesday 05/05...... 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)................ Weak PVA Potential height of wave....................... 39198 ft MSL (33875 ft AGL) Wave soaring outlook for Tuesday 05/05......... Poor Remarks... None Sunrise/Sunset.................... 05:56:12 / 19:56:02 MDT Total possible sunshine........... 13 hr 59 min 51 sec (839 min 51 sec) Altitude of sun at 12:56:18 MDT... 66.39 degrees Upper air data from numerical model forecast valid on 05/04/2009 at 0600 MDT Freezing level.................. 11604 ft MSL (6281 ft AGL) Convective condensation level... 14124 ft MSL (8801 ft AGL) Lifted condensation level....... 13703 ft MSL (8380 ft AGL) Lifted index.................... -0.6 K index......................... +17.4 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 -72.0 276 43 22 0.8 0.4 101.0 213.8 46.9 M M 45000 -56.6 -69.9 278 55 28 0.1 0.1 80.5 176.9 37.4 M M 40000 -59.3 -74.7 277 67 35 -1.8 -1.0 51.7 125.1 21.2 M M 38000 -58.5 -73.3 276 68 35 3.6 2.0 44.1 111.4 16.7 M M 36000 -56.4 -69.5 275 67 34 3.6 2.0 38.6 101.5 13.3 M M 34000 -53.6 -64.5 273 64 33 8.5 4.7 34.6 94.2 10.8 M M 32000 -48.6 -55.5 271 61 31 8.4 4.6 33.3 92.0 10.2 M M 30000 -43.5 -46.3 268 58 30 8.6 4.7 32.4 90.4 9.7 M M 29000 -40.3 -40.5 268 57 29 8.6 4.7 31.7 89.1 9.4 M M 28000 -37.8 -36.0 267 55 29 8.6 4.7 31.3 88.4 9.1 M M 27000 -35.3 -31.5 267 54 28 7.5 4.1 30.9 87.6 8.9 M M 26000 -33.1 -27.6 265 51 26 7.5 4.1 29.9 85.9 8.2 M M 25000 -30.8 -23.4 262 48 25 7.5 4.1 29.1 84.4 7.6 M M 24000 -28.6 -19.5 259 45 23 7.7 4.3 28.4 83.1 7.1 M M 23000 -26.3 -15.3 262 44 23 7.9 4.4 27.6 81.7 6.6 M M 22000 -23.9 -11.0 265 43 22 7.9 4.4 27.0 80.5 6.1 M M 21000 -21.6 -6.9 267 43 22 7.5 4.1 26.3 79.4 5.6 M M 20000 -19.3 -2.7 270 41 21 7.5 4.1 25.5 77.9 4.9 M M 19500 -18.2 -0.8 271 40 21 7.5 4.1 25.1 77.2 4.6 M M 19000 -17.1 1.2 272 40 20 7.5 4.1 24.7 76.5 4.3 M M 18500 -16.0 3.2 274 39 20 7.9 4.3 24.4 75.9 4.0 M M 18000 -14.8 5.4 274 37 19 8.0 4.4 24.1 75.4 3.8 M M 17500 -13.6 7.5 275 36 19 8.0 4.4 23.8 74.9 3.5 M M 17000 -12.5 9.5 275 35 18 7.2 4.0 23.4 74.2 3.2 M M 16500 -11.4 11.5 276 33 17 7.3 4.0 23.0 73.4 2.8 M M 16000 -9.8 14.4 277 31 16 7.8 4.3 22.5 72.4 2.4 M M 15500 -8.6 16.5 278 29 15 7.8 4.3 22.1 71.8 2.1 M M 15000 -7.5 18.5 280 27 14 7.5 4.1 21.8 71.2 1.8 M M 14500 -6.4 20.5 281 25 13 7.5 4.1 21.4 70.6 1.4 M M 14000 -5.2 22.6 283 23 12 7.5 4.1 21.1 69.9 1.1 M M 13500 -4.1 24.6 285 21 11 7.5 4.1 20.7 69.2 0.8 M M 13000 -3.0 26.6 287 19 10 7.5 4.1 20.3 68.6 0.5 M M 12500 -1.9 28.6 288 17 9 7.5 4.1 20.0 67.9 0.1 M M 12000 -0.8 30.6 289 16 8 7.4 4.1 19.6 67.3 -0.2 536 2.7 11500 0.3 32.5 289 15 7 7.3 4.0 19.2 66.6 -0.6 489 2.5 11000 1.4 34.5 289 13 7 7.6 4.2 18.8 65.9 -1.0 442 2.2 10500 2.5 36.5 287 12 6 7.9 4.3 18.5 65.3 -1.3 393 2.0 10250 3.1 37.6 287 12 6 7.9 4.4 18.4 65.1 -1.5 369 1.9 10000 3.7 38.7 286 11 6 7.8 4.3 18.2 64.8 -1.7 344 1.7 9750 4.2 39.6 283 10 5 7.7 4.2 18.1 64.5 -1.8 320 1.6 9500 4.8 40.6 280 9 5 7.7 4.2 17.9 64.2 -2.0 297 1.5 9250 5.3 41.5 275 8 4 7.7 4.2 17.8 64.0 -2.2 273 1.4 9000 5.9 42.6 270 7 4 7.7 4.2 17.6 63.7 -2.4 249 1.3 8750 6.4 43.5 261 7 3 7.6 4.2 17.4 63.4 -2.6 225 1.1 8500 7.0 44.6 251 6 3 7.7 4.2 17.3 63.1 -2.8 202 1.0 8250 7.5 45.5 239 6 3 7.4 4.1 17.1 62.8 -3.0 178 0.9 8000 8.0 46.4 232 6 3 6.6 3.6 16.9 62.4 -3.2 155 0.8 7750 8.5 47.3 229 6 3 6.4 3.5 16.6 61.9 -3.5 134 0.7 7500 8.9 48.0 226 6 3 6.5 3.6 16.4 61.5 -3.7 113 0.6 7250 9.4 48.9 222 5 3 6.2 3.4 16.1 61.0 -4.0 91 0.5 7000 9.8 49.6 229 6 3 5.7 3.1 15.8 60.5 -4.3 71 0.4 6750 10.3 50.5 236 6 3 6.3 3.5 15.5 60.0 -4.6 51 0.3 6500 10.7 51.3 242 7 3 4.1 2.3 15.2 59.4 -4.9 31 0.2 6250 10.7 51.3 243 7 4 -5.2 -2.9 14.5 58.1 -5.7 24 0.1 6000 9.9 49.8 239 7 4 -10.7 -5.9 13.1 55.5 -7.2 39 0.2 5750 9.2 48.6 234 7 4 -7.1 -3.9 11.7 53.0 -8.7 54 0.3 5500 8.4 47.1 230 7 4 -15.7 -8.6 10.3 50.5 -10.2 69 0.3 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 05/04/2009 at 0900 MDT | 05/04/2009 at 1200 MDT | K index... +23.1 | K index... +23.4 | 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 -57.8 -72.0 283 45 23 -0.0 -0.0 | -58.8 -73.8 287 48 25 0.2 0.1 45000 -57.9 -72.2 281 60 31 -0.0 -0.0 | -58.5 -73.3 290 61 31 -0.3 -0.1 40000 -57.9 -72.2 289 68 35 0.0 0.0 | -59.8 -75.6 299 86 44 -0.9 -0.5 38000 -57.2 -71.0 290 67 34 2.1 1.2 | -57.9 -72.2 300 89 46 5.9 3.2 36000 -55.9 -68.6 287 62 32 2.1 1.2 | -54.4 -65.9 300 88 45 5.9 3.2 34000 -53.8 -64.8 284 57 29 8.6 4.7 | -50.6 -59.1 301 84 43 7.1 3.9 32000 -48.8 -55.8 279 52 27 8.4 4.6 | -46.3 -51.3 304 73 37 7.2 3.9 30000 -43.8 -46.8 274 48 25 8.4 4.6 | -41.6 -42.9 303 59 30 6.9 3.8 29000 -40.6 -41.1 274 47 24 8.4 4.6 | -39.5 -39.1 298 52 27 6.9 3.8 28000 -38.1 -36.6 274 46 24 8.4 4.6 | -37.4 -35.3 290 46 24 6.9 3.8 27000 -35.7 -32.3 274 45 23 8.2 4.5 | -35.3 -31.5 283 42 22 9.0 4.9 26000 -33.2 -27.8 274 44 23 8.2 4.5 | -32.6 -26.7 281 41 21 9.0 4.9 25000 -30.8 -23.4 275 44 23 8.2 4.5 | -29.9 -21.8 278 41 21 9.0 4.9 24000 -28.4 -19.1 275 43 22 7.9 4.3 | -27.2 -17.0 276 41 21 8.1 4.4 23000 -26.1 -15.0 275 44 23 7.7 4.2 | -25.0 -13.0 275 40 21 7.6 4.2 22000 -23.8 -10.8 275 45 23 7.7 4.2 | -22.8 -9.0 274 39 20 7.6 4.2 21000 -21.5 -6.7 275 45 23 7.7 4.2 | -20.5 -4.9 273 38 20 7.3 4.0 20000 -19.3 -2.7 275 45 23 7.7 4.2 | -18.4 -1.1 275 36 19 7.3 4.0 19500 -18.1 -0.6 275 45 23 7.7 4.2 | -17.3 0.9 276 35 18 7.3 4.0 19000 -17.0 1.4 275 45 23 7.7 4.2 | -16.3 2.7 276 34 18 7.3 4.0 18500 -15.9 3.4 275 45 23 6.8 3.8 | -15.2 4.6 277 33 17 7.1 3.9 18000 -15.0 5.0 275 43 22 6.4 3.5 | -14.2 6.4 278 32 17 6.9 3.8 17500 -14.0 6.8 274 41 21 6.3 3.5 | -13.2 8.2 279 31 16 6.9 3.8 17000 -13.2 8.2 273 38 19 5.7 3.1 | -12.2 10.0 279 30 15 6.2 3.4 16500 -12.4 9.7 271 34 17 5.7 3.1 | -11.3 11.7 279 28 15 6.3 3.5 16000 -11.0 12.2 266 28 14 6.6 3.6 | -10.0 14.0 278 26 14 5.6 3.1 15500 -10.0 14.0 261 23 12 6.4 3.5 | -9.2 15.4 277 25 13 5.7 3.1 15000 -9.0 15.8 255 19 10 7.6 4.2 | -8.3 17.1 275 23 12 5.9 3.2 14500 -7.9 17.8 248 16 8 7.5 4.1 | -7.5 18.5 272 21 11 5.9 3.2 14000 -6.7 19.9 239 13 7 8.2 4.5 | -6.6 20.1 268 20 10 6.1 3.3 13500 -5.5 22.1 232 11 6 8.3 4.5 | -5.8 21.6 265 18 9 6.2 3.4 13000 -4.2 24.4 223 10 5 8.6 4.7 | -4.9 23.2 260 17 9 6.2 3.4 12500 -3.0 26.6 216 9 4 8.7 4.8 | -4.0 24.8 257 15 8 6.2 3.4 12000 -1.7 28.9 208 8 4 8.7 4.8 | -3.1 26.4 254 14 7 6.0 3.3 11500 -0.4 31.3 201 8 4 8.8 4.8 | -2.2 28.0 253 12 6 5.9 3.2 11000 0.9 33.6 194 8 4 8.7 4.8 | -1.4 29.5 252 10 5 6.0 3.3 10500 2.2 36.0 190 8 4 8.7 4.8 | -0.5 31.1 256 8 4 6.1 3.4 10250 2.8 37.0 189 8 4 8.7 4.7 | -0.0 32.0 259 6 3 6.1 3.3 10000 3.4 38.1 187 8 4 8.9 4.9 | 0.4 32.7 265 5 3 7.2 3.9 9750 4.1 39.4 187 8 4 9.0 5.0 | 1.0 33.8 278 4 2 8.0 4.4 9500 4.7 40.5 187 8 4 9.0 5.0 | 1.6 34.9 295 4 2 7.8 4.3 9250 5.4 41.7 187 8 4 8.9 4.9 | 2.2 36.0 313 4 2 7.8 4.3 9000 6.0 42.8 187 8 4 8.1 4.5 | 2.7 36.9 331 4 2 7.6 4.1 8750 6.6 43.9 186 8 4 7.6 4.2 | 3.3 37.9 346 5 3 7.4 4.1 8500 7.2 45.0 185 8 4 7.9 4.3 | 3.8 38.8 356 7 3 7.6 4.1 8250 7.7 45.9 185 8 4 7.3 4.0 | 4.4 39.9 002 8 4 7.2 3.9 8000 8.2 46.8 185 7 3 6.3 3.5 | 4.9 40.8 007 9 5 6.5 3.6 7750 8.7 47.7 186 5 3 5.8 3.2 | 5.3 41.5 011 10 5 6.5 3.6 7500 9.1 48.4 188 4 2 6.7 3.7 | 5.8 42.4 015 11 5 6.5 3.6 7250 9.6 49.3 193 2 1 3.7 2.0 | 6.3 43.3 017 11 6 6.5 3.5 7000 9.6 49.3 200 1 0 0.6 0.3 | 6.7 44.1 017 12 6 6.4 3.5 6750 9.7 49.5 005 1 0 1.2 0.7 | 7.2 45.0 016 12 6 6.3 3.5 6500 9.8 49.6 009 2 1 1.3 0.7 | 7.6 45.7 016 12 6 6.9 3.8 6250 9.9 49.8 011 3 2 2.3 1.3 | 8.1 46.6 015 12 6 8.0 4.4 6000 10.0 50.0 015 3 1 3.0 1.6 | 8.7 47.7 013 11 6 7.9 4.4 5750 10.1 50.2 020 3 1 2.2 1.2 | 9.3 48.7 012 10 5 8.7 4.8 5500 10.3 50.5 026 2 1 7.7 4.2 | 10.0 50.0 010 9 5 13.7 7.5 05/04/2009 at 1500 MDT | 05/04/2009 at 1800 MDT | K index... +21.2 | K index... +20.8 | 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 -59.3 -74.7 289 52 27 -0.2 -0.1 | -61.0 -77.8 292 56 29 -0.1 -0.1 45000 -59.6 -75.3 292 69 35 -0.0 -0.0 | -61.1 -78.0 299 78 40 0.8 0.4 40000 -59.4 -74.9 300 94 48 0.1 0.1 | -60.0 -76.0 306 99 51 0.9 0.5 38000 -57.3 -71.1 301 95 49 5.5 3.0 | -56.9 -70.4 305 101 52 7.1 3.9 36000 -54.0 -65.2 301 90 46 5.5 3.0 | -52.6 -62.7 303 100 51 7.1 3.9 34000 -50.3 -58.5 299 85 44 8.0 4.4 | -48.3 -54.9 302 97 50 7.6 4.2 32000 -45.5 -49.9 295 81 41 8.1 4.4 | -43.7 -46.7 302 91 47 7.6 4.2 30000 -40.1 -40.2 291 73 38 7.6 4.2 | -38.5 -37.3 303 84 43 7.9 4.3 29000 -37.9 -36.2 290 67 35 7.6 4.2 | -36.1 -33.0 302 81 41 7.9 4.3 28000 -35.6 -32.1 290 61 32 7.6 4.2 | -33.8 -28.8 302 77 40 7.9 4.3 27000 -33.3 -27.9 290 56 29 8.3 4.6 | -31.5 -24.7 302 73 38 7.5 4.1 26000 -30.8 -23.4 289 52 27 8.3 4.5 | -29.2 -20.6 301 67 35 7.6 4.2 25000 -28.4 -19.1 288 47 24 8.3 4.5 | -26.9 -16.4 301 61 32 7.6 4.2 24000 -25.9 -14.6 287 43 22 7.4 4.0 | -24.7 -12.5 300 56 29 6.9 3.8 23000 -23.9 -11.0 287 44 23 6.9 3.8 | -22.7 -8.9 295 53 28 6.7 3.7 22000 -21.8 -7.2 286 45 23 6.9 3.8 | -20.8 -5.4 290 51 26 6.7 3.7 21000 -19.8 -3.6 285 45 23 5.9 3.2 | -18.8 -1.8 286 49 25 6.6 3.6 20000 -18.1 -0.6 285 46 24 5.9 3.2 | -16.8 1.8 286 49 25 6.7 3.7 19500 -17.3 0.9 285 47 24 5.9 3.2 | -15.8 3.6 286 48 25 6.7 3.7 19000 -16.4 2.5 285 47 24 5.9 3.2 | -14.9 5.2 285 48 25 6.7 3.7 18500 -15.6 3.9 285 47 24 6.6 3.6 | -13.9 7.0 285 47 24 5.8 3.2 18000 -14.5 5.9 284 46 24 6.9 3.8 | -13.1 8.4 285 45 23 5.5 3.0 17500 -13.5 7.7 284 44 23 7.0 3.8 | -12.3 9.9 285 43 22 5.5 3.0 17000 -12.6 9.3 284 42 22 6.3 3.4 | -11.5 11.3 284 41 21 5.4 3.0 16500 -11.2 11.8 284 40 20 6.5 3.6 | -10.4 13.3 281 37 19 5.6 3.1 16000 -10.2 13.6 284 38 19 7.1 3.9 | -9.5 14.9 280 34 17 6.4 3.5 15500 -9.1 15.6 284 36 18 7.1 3.9 | -8.5 16.7 279 31 16 6.4 3.5 15000 -8.1 17.4 284 34 17 7.1 3.9 | -7.6 18.3 278 29 15 6.9 3.8 14500 -7.0 19.4 283 32 17 7.1 3.9 | -6.6 20.1 279 27 14 6.9 3.8 14000 -6.0 21.2 283 30 16 7.5 4.1 | -5.6 21.9 280 26 14 6.8 3.7 13500 -4.9 23.2 283 28 15 7.6 4.2 | -4.6 23.7 282 26 13 6.8 3.7 13000 -3.8 25.2 283 26 14 7.5 4.1 | -3.6 25.5 283 25 13 7.0 3.8 12500 -2.7 27.1 283 24 13 7.5 4.1 | -2.5 27.5 285 24 12 7.1 3.9 12000 -1.6 29.1 283 23 12 7.4 4.1 | -1.5 29.3 287 23 12 7.3 4.0 11500 -0.5 31.1 284 21 11 7.4 4.0 | -0.4 31.3 289 20 10 7.4 4.1 11000 0.6 33.1 284 19 10 7.4 4.0 | 0.6 33.1 291 17 9 7.6 4.2 10500 1.7 35.1 283 17 9 7.4 4.1 | 1.8 35.2 295 13 7 7.8 4.3 10250 2.2 36.0 282 16 8 7.4 4.1 | 2.3 36.1 298 12 6 7.8 4.3 10000 2.7 36.9 282 15 7 7.4 4.1 | 2.9 37.2 301 10 5 8.0 4.4 9750 3.3 37.9 280 13 7 7.4 4.1 | 3.5 38.3 304 9 5 8.2 4.5 9500 3.8 38.8 279 11 6 7.4 4.1 | 4.1 39.4 309 8 4 8.2 4.5 9250 4.3 39.7 277 9 5 7.4 4.1 | 4.7 40.5 315 7 3 8.3 4.6 9000 4.8 40.6 274 8 4 7.3 4.0 | 5.3 41.5 322 6 3 9.0 4.9 8750 5.3 41.5 269 6 3 7.2 4.0 | 6.0 42.8 329 5 3 9.4 5.1 8500 5.8 42.4 260 4 2 7.1 3.9 | 6.7 44.1 337 5 2 9.2 5.1 8250 6.3 43.3 240 3 1 7.8 4.3 | 7.3 45.1 347 4 2 9.4 5.1 8000 7.0 44.6 223 2 1 9.2 5.1 | 8.0 46.4 354 4 2 9.5 5.2 7750 7.7 45.9 217 2 1 9.6 5.2 | 8.7 47.7 359 4 2 9.6 5.3 7500 8.4 47.1 209 2 1 9.4 5.2 | 9.4 48.9 004 4 2 9.5 5.2 7250 9.0 48.2 200 2 1 9.7 5.3 | 10.1 50.2 009 4 2 9.8 5.4 7000 9.8 49.6 201 2 1 10.0 5.5 | 10.9 51.6 010 5 2 10.1 5.5 6750 10.5 50.9 201 2 1 9.8 5.4 | 11.6 52.9 010 5 2 10.0 5.5 6500 11.3 52.3 201 2 1 10.1 5.5 | 12.4 54.3 011 5 2 10.0 5.5 6250 12.0 53.6 202 2 1 10.5 5.8 | 13.1 55.6 012 5 2 9.9 5.4 6000 12.8 55.0 204 2 1 11.1 6.1 | 13.9 57.0 012 5 2 10.0 5.5 5750 13.6 56.5 205 2 1 9.9 5.4 | 14.6 58.3 012 5 2 9.6 5.3 5500 14.4 57.9 206 2 1 14.6 8.0 | 15.3 59.5 012 4 2 12.0 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: 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