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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000 UXUS97 KPUB 131215 SRGPUB SOARING FORECAST NATIONAL WEATHER SERVICE PUEBLO CO 615 AM MDT MON MAY 13 2013 EXPERIMENTAL PRODUCT This forecast is for Monday May 13, 2013: If the trigger temperature of 65.0 F/18.3 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1538 ft/min (7.8 m/s) Maximum height of thermals.................. 24474 ft MSL (16811 ft AGL) Forecast maximum temperature................... 81.0 F/27.7 C Time of trigger temperature.................... 0830 MDT Time of overdevelopment........................ None Middle/high clouds during soaring window....... Overcast thin high Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 19041 ft MSL (11378 ft AGL) Thermal soaring outlook for Tuesday 05/14...... Excellent Wave Soaring Index............................. Poor Wave Soaring Index trend (to 1800 MDT)......... Poor Height of stable layer (12-18K ft MSL)......... None Weak PVA/NVA (through 1800 MDT)................ Neither Potential height of wave....................... 15794 ft MSL (8131 ft AGL) Wave soaring outlook for Tuesday 05/14......... Poor Remarks... Sunrise/Sunset.................... 05:48:17 / 20:02:47 MDT Total possible sunshine........... 14 hr 14 min 29 sec (854 min 29 sec) Altitude of sun at 12:55:43 MDT... 69.57 degrees Upper air data from numerical model forecast valid on 05/13/2013 at 0600 MDT Freezing level.................. 14147 ft MSL (6484 ft AGL) Convective condensation level... 19099 ft MSL (11436 ft AGL) Lifted condensation level....... 20581 ft MSL (12918 ft AGL) Lifted index.................... -3.8 K index......................... +11.2 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 -65.6 -86.1 008 20 10 -0.8 -0.5 77.7 171.8 29.9 M M 45000 -66.2 -87.2 024 31 16 2.8 1.5 54.3 129.7 17.1 M M 40000 -61.6 -78.9 026 42 22 6.0 3.3 37.9 100.3 7.3 M M 38000 -56.7 -70.1 025 37 19 8.2 4.5 36.2 97.1 6.3 M M 36000 -51.7 -61.1 023 32 16 8.2 4.5 35.1 95.2 5.7 M M 34000 -46.9 -52.4 020 29 15 7.9 4.3 33.6 92.5 4.7 M M 32000 -42.2 -44.0 016 29 15 7.9 4.3 32.2 89.9 3.7 M M 30000 -37.4 -35.3 012 26 13 8.2 4.5 30.8 87.5 2.8 M M 29000 -34.9 -30.8 010 24 13 8.2 4.5 30.2 86.4 2.3 M M 28000 -32.5 -26.5 008 23 12 8.2 4.5 29.7 85.5 1.9 M M 27000 -29.5 -21.1 004 20 11 8.0 4.4 28.8 83.9 1.2 M M 26000 -27.1 -16.8 359 19 10 8.0 4.4 28.2 82.7 0.7 M M 25000 -24.7 -12.5 354 17 9 8.1 4.4 27.6 81.8 0.2 M M 24000 -22.4 -8.3 351 16 8 7.8 4.3 26.9 80.4 -0.4 1582 8.0 23000 -20.0 -4.0 348 16 8 7.8 4.3 26.2 79.2 -1.0 1483 7.5 22000 -17.7 0.1 345 15 8 7.9 4.4 25.6 78.1 -1.5 1383 7.0 21000 -15.2 4.6 349 15 8 8.4 4.6 25.0 77.1 -2.1 1280 6.5 20000 -12.8 9.0 354 15 8 8.4 4.6 24.6 76.2 -2.6 1176 6.0 19500 -11.5 11.3 357 15 8 8.5 4.7 24.4 75.9 -2.8 1124 5.7 19000 -10.3 13.5 001 15 8 7.4 4.0 24.1 75.4 -3.0 1073 5.5 18500 -9.2 15.4 005 15 8 7.4 4.0 23.7 74.6 -3.4 1025 5.2 18000 -8.1 17.4 010 15 8 7.0 3.8 23.3 73.9 -3.7 976 5.0 17500 -7.1 19.2 007 16 8 6.4 3.5 22.7 72.9 -4.3 932 4.7 17000 -6.1 21.0 005 18 9 6.3 3.5 22.2 71.9 -4.8 889 4.5 16500 -5.2 22.6 001 19 10 6.7 3.7 21.6 71.0 -5.3 845 4.3 16000 -4.2 24.4 355 20 10 6.7 3.7 21.1 70.1 -5.9 802 4.1 15500 -3.3 26.1 351 21 11 7.5 4.1 20.7 69.2 -6.4 758 3.9 15000 -2.2 28.0 350 20 11 7.8 4.3 20.4 68.7 -6.8 710 3.6 14500 -1.0 30.2 349 20 10 8.1 4.4 20.1 68.1 -7.2 661 3.4 14000 0.2 32.4 350 19 10 8.4 4.6 19.8 67.7 -7.4 610 3.1 13500 1.4 34.5 352 17 9 8.4 4.6 19.6 67.3 -7.7 558 2.8 13000 2.7 36.9 355 16 8 8.6 4.7 19.4 67.0 -7.9 505 2.6 12500 4.0 39.2 358 15 8 8.6 4.7 19.2 66.6 -8.1 452 2.3 12000 5.3 41.5 360 14 7 8.8 4.8 19.1 66.3 -8.4 398 2.0 11750 5.9 42.6 360 14 7 8.7 4.8 19.0 66.2 -8.5 371 1.9 11500 6.6 43.9 001 14 7 8.8 4.8 18.9 66.1 -8.5 344 1.7 11250 7.3 45.1 001 13 7 8.7 4.8 18.8 65.9 -8.6 317 1.6 11000 7.9 46.2 001 13 7 8.7 4.8 18.8 65.8 -8.7 290 1.5 10750 8.6 47.5 360 13 7 8.7 4.8 18.7 65.6 -8.9 263 1.3 10500 9.2 48.6 360 13 7 8.7 4.8 18.6 65.5 -9.0 236 1.2 10250 10.6 51.1 358 12 6 9.5 5.2 18.5 65.3 -9.1 180 0.9 10000 11.3 52.3 357 12 6 9.4 5.2 18.5 65.3 -9.2 152 0.8 9750 12.0 53.6 356 12 6 9.3 5.1 18.5 65.2 -9.2 124 0.6 9500 12.6 54.7 354 12 6 6.4 3.5 18.3 65.0 -9.4 98 0.5 9250 12.9 55.2 350 12 6 3.9 2.1 18.0 64.3 -9.8 80 0.4 9000 13.3 55.9 346 12 6 6.2 3.4 17.6 63.6 -10.2 62 0.3 8750 13.6 56.5 342 13 6 -0.5 -0.3 17.2 62.9 -10.6 45 0.2 8500 12.8 55.0 334 12 6 -21.2 -11.6 15.7 60.2 -12.1 61 0.3 8250 10.7 51.3 319 10 5 -31.5 -17.3 12.8 55.0 -15.1 119 0.6 8000 8.5 47.3 298 9 5 -24.2 -13.3 9.9 49.8 -18.0 177 0.9 7750 6.3 43.3 277 9 5 -43.0 -23.6 7.1 44.7 -20.9 234 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 * * * * * * 05/13/2013 at 0900 MDT | 05/13/2013 at 1200 MDT | K index... +16.4 | K index... +20.2 | 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 -66.4 -87.5 016 14 7 -1.5 -0.8 | -67.6 -89.7 025 8 4 -1.8 -1.0 45000 -67.3 -89.1 039 26 13 3.9 2.2 | -68.6 -91.5 055 20 10 4.9 2.7 40000 -61.3 -78.3 046 36 19 6.8 3.7 | -61.3 -78.3 061 27 14 6.8 3.7 38000 -56.5 -69.7 041 32 16 8.1 4.4 | -56.4 -69.5 058 25 13 8.3 4.5 36000 -51.6 -60.9 034 28 14 8.1 4.4 | -50.8 -59.4 053 23 12 8.3 4.6 34000 -46.6 -51.9 027 27 14 8.4 4.6 | -45.7 -50.3 047 22 11 8.5 4.7 32000 -41.6 -42.9 021 28 14 8.4 4.6 | -40.6 -41.1 040 21 11 8.5 4.7 30000 -36.6 -33.9 018 25 13 8.1 4.4 | -35.7 -32.3 032 19 10 8.1 4.4 29000 -34.2 -29.6 016 23 12 8.1 4.4 | -33.3 -27.9 027 18 9 8.1 4.4 28000 -31.2 -24.2 013 20 10 7.9 4.3 | -30.9 -23.6 021 16 8 8.0 4.4 27000 -28.9 -20.0 009 18 9 7.6 4.2 | -28.7 -19.7 013 16 8 7.3 4.0 26000 -26.7 -16.1 003 16 8 7.6 4.2 | -26.5 -15.7 005 15 8 7.3 4.0 25000 -24.4 -11.9 356 15 8 7.6 4.2 | -24.4 -11.9 356 15 8 7.3 4.0 24000 -22.2 -8.0 347 14 7 7.3 4.0 | -22.2 -8.0 350 15 8 7.4 4.1 23000 -20.0 -4.0 338 14 7 7.4 4.0 | -19.5 -3.1 345 16 8 7.4 4.1 22000 -17.8 -0.0 330 15 8 7.6 4.1 | -17.3 0.9 341 16 8 7.5 4.1 21000 -15.5 4.1 329 15 8 8.1 4.5 | -15.1 4.8 334 17 9 7.6 4.2 20000 -13.0 8.6 329 15 8 8.1 4.5 | -12.8 9.0 328 17 9 7.6 4.2 19500 -11.8 10.8 330 15 7 8.2 4.5 | -11.7 10.9 325 18 9 7.6 4.2 19000 -10.7 12.7 332 15 8 7.6 4.1 | -10.6 12.9 325 17 9 7.3 4.0 18500 -9.5 14.9 338 15 8 7.6 4.2 | -9.5 14.9 328 17 9 7.3 4.0 18000 -8.4 16.9 343 16 8 7.5 4.1 | -8.5 16.7 331 16 8 6.2 3.4 17500 -7.3 18.9 348 17 9 7.5 4.1 | -7.6 18.3 335 16 8 5.7 3.1 17000 -6.1 21.0 352 19 10 7.5 4.1 | -6.8 19.8 340 16 8 6.0 3.3 16500 -5.1 22.8 352 20 10 6.9 3.8 | -5.7 21.7 341 15 8 8.4 4.6 16000 -4.1 24.6 350 20 10 7.0 3.8 | -4.5 23.9 342 15 7 8.2 4.5 15500 -3.0 26.6 348 20 10 7.9 4.3 | -3.3 26.1 342 14 7 8.9 4.9 15000 -1.8 28.8 346 19 10 8.1 4.4 | -2.0 28.4 341 12 6 9.0 4.9 14500 -0.7 30.7 344 17 9 8.1 4.4 | -0.7 30.7 339 11 6 9.0 4.9 14000 0.5 32.9 345 16 8 8.1 4.5 | 0.7 33.3 340 9 4 9.1 5.0 13500 1.7 35.1 346 15 8 8.2 4.5 | 2.0 35.6 341 6 3 9.3 5.1 13000 3.0 37.4 348 14 7 8.3 4.5 | 3.4 38.1 343 6 3 9.7 5.3 12500 4.2 39.6 350 13 6 8.3 4.5 | 4.8 40.6 346 5 3 9.8 5.4 12000 5.4 41.7 352 12 6 8.4 4.6 | 6.3 43.3 347 5 2 10.1 5.5 11750 6.1 43.0 352 11 6 8.4 4.6 | 7.1 44.8 348 5 2 10.1 5.5 11500 6.7 44.1 353 11 6 8.4 4.6 | 7.8 46.0 349 5 2 10.1 5.5 11250 7.4 45.3 353 10 5 8.7 4.8 | 8.6 47.5 349 5 2 10.0 5.5 11000 8.0 46.4 352 10 5 8.8 4.8 | 9.3 48.7 350 5 2 9.9 5.4 10750 8.7 47.7 351 9 5 8.8 4.8 | 10.1 50.2 351 5 2 9.9 5.5 10500 9.3 48.7 350 9 5 8.8 4.8 | 10.8 51.4 352 5 2 9.9 5.4 10250 10.7 51.3 345 8 4 9.4 5.2 | 11.5 52.7 353 5 2 9.8 5.4 10000 11.4 52.5 341 8 4 9.4 5.1 | 12.3 54.1 355 5 2 9.8 5.4 9750 12.1 53.8 337 7 4 9.3 5.1 | 13.7 56.7 357 5 2 9.9 5.4 9500 12.8 55.0 333 7 4 8.9 4.9 | 14.5 58.1 358 5 2 10.2 5.6 9250 13.4 56.1 329 7 4 8.8 4.8 | 15.2 59.4 359 5 2 10.5 5.8 9000 14.0 57.2 325 7 4 8.5 4.7 | 16.0 60.8 359 5 2 9.8 5.4 8750 14.7 58.5 321 7 4 9.8 5.4 | 16.8 62.2 360 5 2 12.3 6.7 8500 15.5 59.9 317 7 4 12.5 6.9 | 17.8 64.0 005 4 2 16.5 9.1 8250 16.4 61.5 311 7 3 13.3 7.3 | 19.1 66.4 012 4 2 17.3 9.5 8000 17.3 63.1 305 6 3 12.9 7.1 | 20.3 68.5 020 4 2 17.0 9.3 7750 18.2 64.8 299 6 3 14.0 7.7 | 21.6 70.9 028 4 2 17.8 9.7 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 05/13/2013 at 1500 MDT | 05/13/2013 at 1800 MDT | K index... +23.3 | K index... +24.1 | 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 -68.4 -91.1 031 3 2 -1.8 -1.0 | -67.9 -90.2 360 2 1 -1.7 -1.0 45000 -69.2 -92.6 066 17 9 5.4 3.0 | -68.7 -91.7 081 15 8 5.4 2.9 40000 -61.1 -78.0 077 23 12 7.3 4.0 | -60.7 -77.3 092 21 11 7.1 3.9 38000 -56.1 -69.0 076 20 10 8.4 4.6 | -55.8 -68.4 094 17 9 8.2 4.5 36000 -50.5 -58.9 073 17 9 8.4 4.6 | -50.3 -58.5 097 12 6 8.2 4.5 34000 -45.5 -49.9 064 16 8 8.4 4.6 | -45.4 -49.7 085 9 5 8.2 4.5 32000 -40.5 -40.9 053 15 8 8.4 4.6 | -40.4 -40.7 062 8 4 8.2 4.5 30000 -35.6 -32.1 041 13 7 8.2 4.5 | -35.5 -31.9 042 7 4 8.2 4.5 29000 -33.1 -27.6 035 12 6 8.2 4.5 | -33.1 -27.6 033 7 4 8.2 4.5 28000 -30.7 -23.3 027 11 6 8.1 4.4 | -30.6 -23.1 023 7 4 8.2 4.5 27000 -28.4 -19.1 018 12 6 7.7 4.2 | -28.3 -18.9 020 8 4 7.9 4.3 26000 -26.1 -15.0 010 13 7 7.8 4.3 | -25.9 -14.6 018 9 5 7.9 4.4 25000 -23.8 -10.8 003 14 7 7.8 4.3 | -23.6 -10.5 017 10 5 8.0 4.4 24000 -21.6 -6.9 001 14 7 7.1 3.9 | -21.4 -6.5 014 9 5 7.1 3.9 23000 -19.0 -2.2 360 13 7 7.1 3.9 | -18.8 -1.8 010 8 4 7.1 3.9 22000 -16.9 1.6 360 12 6 7.2 3.9 | -16.7 1.9 005 7 4 7.1 3.9 21000 -14.8 5.4 344 13 7 7.3 4.0 | -14.6 5.7 349 7 4 7.2 3.9 20000 -12.7 9.1 330 14 7 7.3 4.0 | -12.5 9.5 334 8 4 7.2 3.9 19500 -11.6 11.1 324 15 8 7.3 4.0 | -11.4 11.5 328 8 4 7.2 4.0 19000 -10.5 13.1 321 15 8 6.9 3.8 | -10.4 13.3 322 9 5 7.5 4.1 18500 -9.5 14.9 318 14 7 6.9 3.8 | -9.3 15.3 317 9 5 7.5 4.1 18000 -8.5 16.7 315 13 7 7.1 3.9 | -8.2 17.2 313 10 5 7.6 4.2 17500 -7.5 18.5 314 11 6 7.2 3.9 | -7.1 19.2 314 8 4 7.6 4.2 17000 -6.5 20.3 314 9 5 7.4 4.0 | -6.0 21.2 316 6 3 7.7 4.2 16500 -5.3 22.5 315 7 3 8.7 4.8 | -4.8 23.4 318 4 2 8.6 4.7 16000 -4.0 24.8 322 4 2 8.5 4.7 | -3.5 25.7 324 2 1 8.4 4.6 15500 -2.7 27.1 333 2 1 9.7 5.3 | -2.2 28.0 000 0 0 9.5 5.2 15000 -1.3 29.7 329 2 1 9.8 5.4 | -0.8 30.6 000 0 0 9.6 5.3 14500 0.2 32.4 324 2 1 9.7 5.3 | 0.6 33.1 000 0 0 9.6 5.3 14000 1.6 34.9 328 1 1 9.7 5.3 | 2.0 35.6 108 1 0 9.5 5.2 13500 3.0 37.4 333 1 1 9.7 5.3 | 3.4 38.1 111 1 0 9.5 5.2 13000 4.5 40.1 333 1 0 9.7 5.3 | 4.9 40.8 118 1 1 9.5 5.2 12500 5.9 42.6 333 1 0 9.7 5.3 | 6.3 43.3 123 2 1 9.5 5.2 12000 7.4 45.3 338 1 0 9.9 5.4 | 7.7 45.9 128 2 1 9.5 5.2 11750 8.1 46.6 000 0 0 9.9 5.4 | 8.4 47.1 130 2 1 9.5 5.2 11500 8.9 48.0 000 0 0 9.9 5.4 | 9.1 48.4 132 2 1 9.5 5.2 11250 9.6 49.3 000 0 0 10.0 5.5 | 9.8 49.6 133 3 1 9.6 5.3 11000 10.3 50.5 000 0 0 10.0 5.5 | 10.5 50.9 135 3 2 9.7 5.3 10750 11.1 52.0 000 0 0 10.0 5.5 | 11.2 52.2 136 3 2 9.7 5.3 10500 11.8 53.2 000 0 0 10.0 5.5 | 12.0 53.6 138 4 2 9.7 5.3 10250 12.6 54.7 000 0 0 9.9 5.5 | 12.7 54.9 139 4 2 9.8 5.4 10000 13.3 55.9 082 1 0 9.9 5.4 | 13.4 56.1 139 4 2 9.8 5.4 9750 14.0 57.2 084 1 0 9.9 5.4 | 14.9 58.8 140 4 2 9.8 5.4 9500 15.5 59.9 088 1 0 9.9 5.4 | 15.6 60.1 141 4 2 9.6 5.3 9250 16.2 61.2 092 1 0 10.0 5.5 | 16.3 61.3 140 5 2 9.5 5.2 9000 17.0 62.6 095 1 1 9.6 5.3 | 17.0 62.6 140 5 2 9.5 5.2 8750 17.7 63.9 098 1 1 11.1 6.1 | 17.7 63.9 140 5 2 9.7 5.3 8500 18.7 65.7 107 1 1 14.5 7.9 | 18.4 65.1 139 5 3 10.6 5.8 8250 19.8 67.6 115 2 1 15.8 8.7 | 19.2 66.6 137 5 3 11.0 6.0 8000 20.9 69.6 119 3 2 15.0 8.2 | 19.9 67.8 135 5 3 10.8 5.9 7750 22.0 71.6 121 4 2 17.1 9.4 | 20.7 69.3 133 6 3 11.5 6.3 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