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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000 UXUS97 KPUB 161016 SRGPUB SOARING FORECAST NATIONAL WEATHER SERVICE PUEBLO CO 416 AM MDT THU MAY 16 2013 EXPERIMENTAL PRODUCT This forecast is for Thursday May 16, 2013: If the trigger temperature of 63.7 F/17.6 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1668 ft/min (8.5 m/s) Maximum height of thermals.................. 24451 ft MSL (16791 ft AGL) Forecast maximum temperature................... 78.0 F/26.0 C Time of trigger temperature.................... 0830 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................. 21505 ft MSL (13845 ft AGL) Thermal soaring outlook for Friday 05/17....... Good 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)................ Weak PVA Potential height of wave....................... 35274 ft MSL (27614 ft AGL) Wave soaring outlook for Friday 05/17.......... Poor Remarks... Sunrise/Sunset.................... 05:45:38 / 20:05:31 MDT Total possible sunshine........... 14 hr 19 min 53 sec (859 min 53 sec) Altitude of sun at 12:55:46 MDT... 70.27 degrees Upper air data from numerical model forecast valid on 05/16/2013 at 0600 MDT Freezing level.................. 13698 ft MSL (6038 ft AGL) Convective condensation level... 15860 ft MSL (8200 ft AGL) Lifted condensation level....... 18801 ft MSL (11141 ft AGL) Lifted index.................... -5.2 K index......................... +17.0 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 -60.8 -77.4 270 19 10 0.7 0.4 85.3 185.5 35.4 M M 45000 -59.9 -75.8 258 21 11 -0.2 -0.1 63.2 145.8 23.9 M M 40000 -60.3 -76.5 265 42 22 -0.8 -0.4 40.3 104.6 10.1 M M 38000 -56.7 -70.1 263 46 23 7.3 4.0 36.9 98.3 7.9 M M 36000 -52.3 -62.1 261 48 25 7.3 4.0 34.9 94.8 6.7 M M 34000 -47.5 -53.5 260 50 26 8.5 4.7 33.4 92.2 5.8 M M 32000 -42.4 -44.3 260 51 26 8.5 4.7 32.5 90.4 5.2 M M 30000 -37.5 -35.5 260 50 26 7.5 4.1 31.2 88.1 4.4 M M 29000 -35.3 -31.5 260 48 25 7.5 4.1 30.3 86.5 3.7 M M 28000 -32.5 -26.5 259 46 24 7.5 4.1 29.3 84.8 3.0 M M 27000 -30.4 -22.7 257 43 22 6.7 3.7 28.3 82.9 2.2 M M 26000 -28.4 -19.1 254 39 20 6.7 3.7 27.1 80.8 1.2 M M 25000 -26.3 -15.3 251 34 18 6.7 3.7 26.0 78.9 0.4 M M 24000 -24.4 -11.9 248 30 16 6.5 3.6 25.0 76.9 -0.5 1621 8.2 23000 -22.4 -8.3 246 27 14 6.5 3.6 23.7 74.7 -1.6 1533 7.8 22000 -20.5 -4.9 245 24 12 6.5 3.6 22.6 72.8 -2.6 1446 7.3 21000 -18.6 -1.5 243 22 11 6.5 3.6 21.5 70.7 -3.6 1358 6.9 20000 -16.6 2.1 241 21 11 6.5 3.6 20.4 68.7 -4.7 1271 6.5 19500 -15.7 3.7 241 21 11 6.6 3.6 19.8 67.7 -5.2 1228 6.2 19000 -14.7 5.5 240 20 11 6.9 3.8 19.4 66.8 -5.7 1184 6.0 18500 -13.5 7.7 241 20 10 8.7 4.8 19.1 66.3 -6.0 1133 5.8 18000 -12.3 9.9 242 20 11 8.6 4.7 18.9 66.0 -6.2 1081 5.5 17500 -11.0 12.2 244 20 11 9.4 5.1 18.8 65.8 -6.4 1026 5.2 17000 -9.5 14.9 247 20 11 9.5 5.2 18.7 65.7 -6.5 969 4.9 16500 -8.1 17.4 250 21 11 9.5 5.2 18.7 65.6 -6.6 912 4.6 16000 -6.7 19.9 253 20 11 9.5 5.2 18.6 65.5 -6.7 854 4.3 15500 -5.3 22.5 256 20 11 9.5 5.2 18.6 65.4 -6.8 797 4.0 15000 -3.9 25.0 259 20 10 9.5 5.2 18.5 65.4 -6.8 740 3.8 14500 -2.5 27.5 261 20 10 9.5 5.2 18.5 65.3 -6.9 683 3.5 14000 -1.0 30.2 264 20 10 9.4 5.1 18.4 65.2 -7.0 626 3.2 13500 0.3 32.5 266 20 10 9.4 5.1 18.4 65.1 -7.1 569 2.9 13000 1.7 35.1 268 20 10 9.4 5.2 18.3 65.0 -7.3 513 2.6 12500 3.1 37.6 267 19 10 9.5 5.2 18.3 64.9 -7.4 456 2.3 12000 4.5 40.1 266 19 10 9.4 5.2 18.2 64.8 -7.5 400 2.0 11750 5.2 41.4 265 18 10 9.4 5.1 18.2 64.8 -7.5 372 1.9 11500 5.9 42.6 264 18 9 9.4 5.1 18.2 64.7 -7.6 344 1.7 11250 6.6 43.9 263 18 9 9.5 5.2 18.1 64.7 -7.7 316 1.6 11000 7.3 45.1 262 18 9 9.0 4.9 18.1 64.6 -7.7 288 1.5 10750 7.9 46.2 260 17 9 8.5 4.7 18.0 64.4 -7.9 262 1.3 10500 8.5 47.3 257 16 8 8.6 4.7 17.9 64.3 -8.0 236 1.2 10250 9.1 48.4 255 15 8 8.8 4.8 17.8 64.1 -8.2 211 1.1 10000 10.2 50.4 248 13 7 7.4 4.1 17.6 63.7 -8.6 162 0.8 9750 10.7 51.3 244 12 6 7.5 4.1 17.4 63.4 -8.8 139 0.7 9500 11.3 52.3 239 11 6 7.9 4.3 17.3 63.1 -9.0 116 0.6 9250 11.8 53.2 233 10 5 5.4 3.0 17.1 62.7 -9.3 94 0.5 9000 12.0 53.6 236 11 6 2.8 1.5 16.6 61.9 -9.8 79 0.4 8750 12.2 54.0 238 12 6 4.6 2.5 16.1 61.0 -10.3 65 0.3 8500 12.4 54.3 240 14 7 0.0 0.0 15.7 60.2 -10.9 51 0.3 8250 11.6 52.9 243 13 7 -24.8 -13.6 14.1 57.5 -12.4 68 0.3 8000 8.6 47.5 249 10 5 -52.3 -28.7 10.4 50.7 -16.2 151 0.8 7750 5.6 42.1 260 7 4 -7.6 -4.2 6.6 43.9 -20.0 235 1.2 7500 M M M M M M M M M M M M 7250 M M M M M M M M M M M M 7000 M M M M M M M M M M M M 6750 M M M M M M M M M M M M * * * * * * Numerical weather prediction model forecast data valid * * * * * * 05/16/2013 at 0900 MDT | 05/16/2013 at 1200 MDT | K index... +13.6 | K index... +16.4 | 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 -60.3 -76.5 258 17 9 0.1 0.1 | -61.3 -78.3 252 19 10 -0.7 -0.4 45000 -60.1 -76.2 262 22 11 -0.0 -0.0 | -62.2 -80.0 262 23 12 0.5 0.3 40000 -60.2 -76.4 279 37 19 -0.7 -0.4 | -61.4 -78.5 285 31 16 -0.4 -0.2 38000 -56.4 -69.5 281 39 20 7.4 4.1 | -57.1 -70.8 285 32 16 8.1 4.4 36000 -51.9 -61.4 283 40 20 7.5 4.1 | -52.2 -62.0 284 32 17 8.1 4.4 34000 -47.3 -53.1 283 40 21 8.0 4.4 | -47.3 -53.1 284 33 17 8.3 4.5 32000 -42.4 -44.3 281 40 21 8.0 4.4 | -42.4 -44.3 284 33 17 8.3 4.6 30000 -37.6 -35.7 280 40 20 8.2 4.5 | -37.4 -35.3 284 32 16 8.1 4.5 29000 -35.1 -31.2 281 39 20 8.2 4.5 | -35.0 -31.0 284 31 16 8.1 4.5 28000 -32.1 -25.8 283 38 20 8.2 4.5 | -31.9 -25.4 284 29 15 8.2 4.5 27000 -29.8 -21.6 283 37 19 7.0 3.8 | -29.6 -21.3 285 28 14 7.3 4.0 26000 -27.7 -17.9 283 35 18 7.0 3.8 | -27.5 -17.5 286 26 14 7.3 4.0 25000 -25.6 -14.1 283 34 17 7.0 3.8 | -25.3 -13.5 287 25 13 7.3 4.0 24000 -23.7 -10.7 282 31 16 6.2 3.4 | -23.2 -9.8 288 24 12 6.4 3.5 23000 -21.8 -7.2 280 27 14 6.2 3.4 | -21.3 -6.3 289 24 12 6.4 3.5 22000 -20.0 -4.0 277 23 12 6.3 3.4 | -19.4 -2.9 290 23 12 6.5 3.5 21000 -18.1 -0.6 276 19 10 6.5 3.6 | -17.5 0.5 287 22 11 6.7 3.7 20000 -16.2 2.8 276 15 8 6.5 3.6 | -15.5 4.1 281 19 10 6.7 3.7 19500 -15.2 4.6 276 13 7 6.6 3.6 | -14.5 5.9 278 18 9 6.8 3.7 19000 -14.2 6.4 277 11 5 6.8 3.7 | -13.5 7.7 274 17 9 7.3 4.0 18500 -13.1 8.4 278 10 5 7.7 4.2 | -12.2 10.0 272 16 8 8.5 4.6 18000 -12.0 10.4 280 10 5 7.6 4.2 | -11.0 12.2 270 15 7 8.4 4.6 17500 -10.8 12.6 283 9 5 8.5 4.7 | -9.7 14.5 270 13 7 8.4 4.6 17000 -9.6 14.7 286 10 5 8.6 4.7 | -8.5 16.7 273 12 6 8.4 4.6 16500 -8.3 17.1 288 10 5 8.8 4.8 | -7.3 18.9 277 11 6 8.3 4.5 16000 -6.9 19.6 289 10 5 9.2 5.0 | -6.1 21.0 282 11 6 8.2 4.5 15500 -5.6 21.9 290 11 6 9.2 5.0 | -4.9 23.2 287 10 5 8.3 4.5 15000 -4.2 24.4 293 11 6 9.3 5.1 | -3.7 25.3 291 10 5 9.0 4.9 14500 -2.8 27.0 298 12 6 9.4 5.1 | -2.4 27.7 295 8 4 8.9 4.9 14000 -1.4 29.5 302 12 6 9.2 5.1 | -1.1 30.0 298 8 4 9.8 5.4 13500 -0.1 31.8 304 13 7 9.2 5.0 | 0.4 32.7 298 8 4 9.7 5.3 13000 1.3 34.3 305 13 7 9.6 5.2 | 1.9 35.4 298 8 4 10.0 5.5 12500 2.8 37.0 304 13 7 9.7 5.3 | 3.4 38.1 299 8 4 10.0 5.5 12000 4.2 39.6 304 13 7 9.5 5.2 | 4.9 40.8 300 7 4 9.9 5.4 11750 4.9 40.8 302 13 7 9.3 5.1 | 5.6 42.1 301 7 4 9.8 5.4 11500 5.6 42.1 300 13 7 9.3 5.1 | 6.3 43.3 301 7 4 9.8 5.4 11250 6.3 43.3 298 13 7 9.3 5.1 | 7.1 44.8 302 7 4 9.8 5.4 11000 7.0 44.6 296 13 7 9.3 5.1 | 7.8 46.0 303 7 4 10.0 5.5 10750 7.7 45.9 292 13 7 9.3 5.1 | 8.5 47.3 303 7 4 10.1 5.6 10500 8.3 46.9 288 13 7 9.3 5.1 | 9.3 48.7 303 7 4 10.1 5.5 10250 9.7 49.5 281 13 7 8.9 4.9 | 10.8 51.4 304 7 4 10.0 5.5 10000 10.3 50.5 279 13 6 8.4 4.6 | 11.5 52.7 305 7 4 9.9 5.4 9750 11.0 51.8 277 12 6 8.5 4.7 | 12.3 54.1 305 7 3 9.9 5.4 9500 11.6 52.9 275 12 6 8.6 4.7 | 13.0 55.4 306 7 3 9.9 5.5 9250 12.2 54.0 274 12 6 7.1 3.9 | 13.8 56.8 306 7 3 10.1 5.5 9000 12.6 54.7 273 13 7 6.2 3.4 | 14.5 58.1 307 7 3 10.3 5.7 8750 13.0 55.4 273 14 7 6.3 3.4 | 15.3 59.5 308 6 3 9.7 5.3 8500 13.4 56.1 273 14 7 7.5 4.1 | 16.1 61.0 309 6 3 11.9 6.5 8250 14.0 57.2 272 14 7 12.1 6.7 | 17.2 63.0 311 6 3 18.2 10.0 8000 15.0 59.0 269 11 6 15.9 8.7 | 18.7 65.7 314 6 3 22.2 12.2 7750 16.0 60.8 265 8 4 10.7 5.9 | 20.2 68.4 319 5 3 17.1 9.4 7500 M M M M M M M | M M M M M M M 7250 M M M M M M M | M M M M M M M 7000 M M M M M M M | M M M M M M M 6750 M M M M M M M | M M M M M M M 05/16/2013 at 1500 MDT | 05/16/2013 at 1800 MDT | K index... +25.9 | K index... +24.3 | 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 -61.7 -79.1 243 23 12 -0.2 -0.1 | -62.4 -80.3 251 26 13 -0.6 -0.3 45000 -61.9 -79.4 262 27 14 0.7 0.4 | -63.0 -81.4 267 29 15 1.2 0.7 40000 -60.8 -77.4 287 30 15 0.1 0.1 | -61.2 -78.2 285 32 17 1.2 0.6 38000 -56.9 -70.4 286 31 16 7.6 4.2 | -56.8 -70.2 287 30 16 8.0 4.4 36000 -51.7 -61.1 283 32 16 7.6 4.2 | -52.0 -61.6 288 28 14 8.0 4.4 34000 -47.0 -52.6 282 31 16 8.2 4.5 | -47.1 -52.8 288 26 13 8.2 4.5 32000 -42.0 -43.6 283 30 15 8.2 4.5 | -42.2 -44.0 288 25 13 8.2 4.5 30000 -37.1 -34.8 284 29 15 8.4 4.6 | -37.2 -35.0 285 24 12 8.4 4.6 29000 -34.6 -30.3 283 28 14 8.4 4.6 | -34.7 -30.5 283 25 13 8.4 4.6 28000 -32.1 -25.8 283 27 14 8.4 4.6 | -31.6 -24.9 281 25 13 8.5 4.7 27000 -29.7 -21.5 282 25 13 7.3 4.0 | -29.2 -20.6 277 24 13 7.6 4.2 26000 -27.6 -17.7 281 24 12 7.3 4.0 | -26.9 -16.4 274 24 12 7.7 4.2 25000 -25.4 -13.7 280 23 12 7.3 4.0 | -24.7 -12.5 269 23 12 7.7 4.2 24000 -23.2 -9.8 279 22 11 6.9 3.8 | -22.5 -8.5 268 22 11 7.3 4.0 23000 -20.7 -5.3 280 22 11 7.0 3.8 | -20.3 -4.5 269 21 11 7.3 4.0 22000 -18.6 -1.5 281 22 11 7.0 3.9 | -18.1 -0.6 270 20 10 7.3 4.0 21000 -16.6 2.1 280 21 11 6.9 3.8 | -16.1 3.0 271 20 10 6.9 3.8 20000 -14.6 5.7 277 19 10 6.9 3.8 | -14.0 6.8 270 20 10 6.9 3.8 19500 -13.6 7.5 276 19 10 6.9 3.8 | -13.0 8.6 270 20 10 6.9 3.8 19000 -12.6 9.3 274 18 9 7.1 3.9 | -12.0 10.4 270 20 10 7.0 3.8 18500 -11.5 11.3 275 15 8 7.2 3.9 | -11.0 12.2 271 18 9 7.0 3.9 18000 -10.5 13.1 277 12 6 7.1 3.9 | -9.9 14.2 272 17 9 7.0 3.8 17500 -9.4 15.1 278 10 5 8.7 4.8 | -8.9 16.0 272 15 8 7.6 4.2 17000 -8.1 17.4 280 8 4 8.5 4.7 | -7.8 18.0 272 13 7 7.6 4.2 16500 -6.9 19.6 284 6 3 9.2 5.1 | -6.7 19.9 272 11 5 8.2 4.5 16000 -5.5 22.1 287 5 3 9.6 5.3 | -5.4 22.3 272 9 5 8.8 4.8 15500 -4.0 24.8 291 5 2 9.7 5.3 | -4.1 24.6 273 7 4 8.9 4.9 15000 -2.6 27.3 293 4 2 10.0 5.5 | -2.7 27.1 273 6 3 10.1 5.5 14500 -1.1 30.0 295 4 2 10.0 5.5 | -1.2 29.8 273 6 3 10.0 5.5 14000 0.4 32.7 296 4 2 9.7 5.3 | 0.3 32.5 273 6 3 9.8 5.4 13500 1.8 35.2 298 4 2 9.7 5.3 | 1.8 35.2 274 5 3 9.8 5.4 13000 3.3 37.9 300 4 2 9.7 5.3 | 3.2 37.8 276 5 3 9.6 5.3 12500 4.7 40.5 301 3 2 9.7 5.3 | 4.6 40.3 279 4 2 9.6 5.3 12000 6.2 43.2 303 3 2 9.8 5.4 | 6.0 42.8 286 3 2 9.4 5.1 11750 6.9 44.4 306 3 2 9.8 5.4 | 6.7 44.1 293 2 1 9.2 5.1 11500 7.7 45.9 308 3 1 9.8 5.4 | 7.4 45.3 305 2 1 9.3 5.1 11250 8.4 47.1 311 3 1 9.8 5.4 | 8.1 46.6 324 2 1 9.2 5.1 11000 9.1 48.4 313 3 1 9.9 5.5 | 8.8 47.8 348 1 1 9.3 5.1 10750 9.9 49.8 315 2 1 10.1 5.5 | 9.5 49.1 005 2 1 9.4 5.2 10500 10.6 51.1 317 2 1 10.0 5.5 | 10.2 50.4 017 2 1 9.4 5.2 10250 11.3 52.3 320 2 1 10.0 5.5 | 11.6 52.9 029 3 2 9.6 5.3 10000 12.1 53.8 322 2 1 10.0 5.5 | 12.3 54.1 030 3 2 9.8 5.4 9750 12.8 55.0 327 2 1 10.0 5.5 | 13.0 55.4 031 4 2 9.8 5.4 9500 14.3 57.7 338 2 1 10.0 5.5 | 13.8 56.8 032 4 2 9.8 5.4 9250 15.0 59.0 343 2 1 9.7 5.3 | 14.5 58.1 032 4 2 9.6 5.3 9000 15.8 60.4 345 2 1 9.5 5.2 | 15.2 59.4 033 4 2 9.6 5.2 8750 16.5 61.7 348 2 1 9.4 5.1 | 15.9 60.6 034 4 2 9.5 5.2 8500 17.2 63.0 351 2 1 10.1 5.5 | 16.6 61.9 035 4 2 9.7 5.3 8250 18.0 64.4 003 2 1 13.6 7.4 | 17.4 63.3 036 4 2 10.6 5.8 8000 19.1 66.4 036 2 1 17.1 9.4 | 18.1 64.6 040 4 2 11.5 6.3 7750 20.2 68.4 059 2 1 11.7 6.4 | 18.8 65.8 044 4 2 10.4 5.7 7500 M M M M M M M | M M M M M M M 7250 M M M M M M M | M M M M M M M 7000 M M M M M M M | M M M M M M M 6750 M M M M M M M | M M M M M M M ________________________________________________________________________________ This product is issued one per day by approximately 0630 MST/0730 MDT (1330 UTC). It is not continuously monitored nor updated after its initial issuance. The information contained herein is based on numerical weather prediction model data taken near the Air Force Academy in Colorado Springs, Colorado at North Latitude: 38 deg 58 min 48.000 sec West Longitude: 104 deg 49 min 12.000 sec Elevation: 6572 feet (2003 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. At this time, the output from this considered experimental. 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
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- Page last modified: May 1st, 2013 15:32 UTC