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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000 UXUS97 KPUB 141205 SRGPUB Soaring Forecast National Weather Service Pueblo, Colorado 0605 MDT Saturday, April 14, 2018 This forecast is for Saturday, April 14, 2018: If the trigger temperature of 27.1 F/-2.7 C is reached...then Thermal Soaring Index....................... Fair Maximum rate of lift........................ 579 ft/min (2.9 m/s) Maximum height of thermals.................. 16581 ft MSL (8955 ft AGL) Forecast maximum temperature................... 44.0 F/7.1 C Time of trigger temperature.................... 0730 MDT Time of overdevelopment........................ None Middle/high clouds during soaring window....... Overcast thin high Surface winds during soaring window............ Between 20 mph and 30 mph Height of the -3 thermal index................. 15085 ft MSL (7459 ft AGL) Thermal soaring outlook for Sunday 04/15....... Fair Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 06:23:42 / 19:35:18 MDT Total possible sunshine........... 13 hr 11 min 35 sec (791 min 35 sec) Altitude of sun at 12:59:30 MDT... 60.60 degrees Upper air data from numerical model forecast valid on 04/14/2018 at 0600 MDT Freezing level.................. Entire airmass below 32 F / 0 C Convective condensation level... 11394 ft MSL (3768 ft AGL) Lifted condensation level....... 15192 ft MSL (7566 ft AGL) Lifted index.................... +5.1 K index......................... -1.6 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 -54.2 -65.6 310 14 7 2.1 1.2 M M M M M 45000 -50.9 -59.6 320 20 10 2.2 1.2 M M M M M 40000 -50.7 -59.3 335 22 11 -0.0 -0.0 M M M M M 38000 -50.8 -59.4 345 24 13 -0.3 -0.1 M M M M M 36000 -51.0 -59.8 345 30 16 -0.3 -0.1 M M M M M 34000 -51.1 -60.0 350 37 19 0.6 0.3 M M M M M 32000 -49.6 -57.3 340 25 13 2.8 1.5 M M M M M 30000 -47.9 -54.2 315 14 7 4.7 2.6 M M M M M 29000 -45.7 -50.3 315 14 7 7.7 4.2 20.6 69.0 10.8 M M 28000 -43.3 -45.9 315 15 8 7.7 4.2 19.7 67.5 10.3 M M 27000 -41.0 -41.8 320 15 8 7.7 4.2 19.1 66.3 9.9 M M 26000 -38.8 -37.8 325 16 8 7.4 4.1 18.3 64.9 9.3 M M 25000 -36.6 -33.9 330 17 9 7.4 4.0 17.3 63.2 8.7 M M 24000 -34.3 -29.7 340 19 10 7.4 4.0 16.5 61.7 8.1 M M 23000 -32.2 -26.0 345 21 11 7.0 3.8 15.6 60.1 7.5 M M 22000 -30.1 -22.2 345 23 12 7.0 3.9 14.6 58.3 6.7 M M 21000 -27.5 -17.5 350 26 13 6.9 3.8 13.5 56.3 5.8 M M 20000 -25.7 -14.3 350 27 14 5.7 3.1 12.1 53.8 4.7 M M 19500 -24.9 -12.8 350 27 14 5.8 3.2 11.4 52.5 4.1 M M 19000 -24.0 -11.2 350 28 14 5.8 3.2 10.7 51.3 3.5 M M 18500 -23.2 -9.8 350 28 14 5.8 3.2 10.1 50.2 3.0 M M 18000 -22.4 -8.3 350 28 15 4.5 2.5 9.3 48.8 2.3 M M 17500 -21.7 -7.1 350 28 15 4.7 2.6 8.5 47.3 1.5 M M 17000 -21.1 -6.0 345 29 15 3.8 2.1 7.6 45.7 0.7 M M 16500 -20.6 -5.1 345 29 15 3.6 2.0 6.6 43.8 -0.2 671 3.4 16000 -20.0 -4.0 345 29 15 3.4 1.9 5.6 42.0 -1.2 641 3.3 15500 -19.6 -3.3 345 29 15 3.1 1.7 4.4 40.0 -2.2 612 3.1 15000 -19.1 -2.4 345 30 15 3.1 1.7 3.4 38.1 -3.2 584 3.0 14500 -18.7 -1.7 345 30 16 3.2 1.7 2.3 36.1 -4.2 556 2.8 14000 -18.2 -0.8 345 31 16 3.1 1.7 1.2 34.2 -5.2 527 2.7 13500 -17.6 0.3 345 31 16 4.3 2.4 0.3 32.5 -6.2 495 2.5 13000 -17.0 1.4 345 32 16 4.2 2.3 -0.6 30.9 -7.1 462 2.3 12500 -16.3 2.7 345 32 17 5.4 3.0 -1.4 29.5 -7.9 427 2.2 12000 -15.5 4.1 345 31 16 5.5 3.0 -2.1 28.3 -8.5 388 2.0 11750 -15.1 4.8 345 31 16 7.3 4.0 -2.4 27.8 -8.9 367 1.9 11500 -14.5 5.9 345 30 16 8.9 4.9 -2.5 27.6 -9.0 341 1.7 11250 -13.8 7.2 345 30 15 7.6 4.2 -2.6 27.4 -9.1 315 1.6 11000 -13.3 8.1 345 29 15 7.0 3.8 -2.8 27.0 -9.4 292 1.5 10750 -12.8 9.0 345 28 15 7.0 3.9 -3.0 26.6 -9.6 269 1.4 10500 -12.3 9.9 345 28 14 6.7 3.7 -3.2 26.2 -9.8 247 1.3 10250 -11.8 10.8 345 27 14 7.4 4.1 -3.4 25.8 -10.1 224 1.1 10000 -11.2 11.8 340 26 14 7.6 4.1 -3.6 25.6 -10.3 200 1.0 9750 -10.7 12.7 340 26 13 6.0 3.3 -3.8 25.1 -10.5 177 0.9 9500 -10.3 13.5 340 25 13 5.2 2.8 -4.1 24.6 -10.9 158 0.8 9250 -9.9 14.2 340 24 12 6.4 3.5 -4.5 24.0 -11.3 138 0.7 9000 -9.4 15.1 340 23 12 7.0 3.8 -4.7 23.6 -11.5 115 0.6 8750 -8.9 16.0 340 21 11 6.3 3.4 -4.9 23.2 -11.8 94 0.5 8500 -8.5 16.7 340 20 10 6.4 3.5 -5.2 22.7 -12.1 73 0.4 8250 -8.0 17.6 335 18 9 6.0 3.3 -5.4 22.2 -12.4 52 0.3 8000 -7.5 18.5 335 16 8 8.2 4.5 -5.7 21.8 -12.7 30 0.2 7750 -6.7 19.9 335 12 6 12.8 7.0 -5.6 21.9 -12.6 M M 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 * * * * * * 04/14/2018 at 0900 MDT | 04/14/2018 at 1200 MDT | CAPE... +4.3 LI... +6.9 | CAPE... +1.2 LI... +6.6 CINH... 0.0 K Index... -25.7 | CINH... 0.0 K Index... -30.8 | 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 -54.9 -66.8 315 13 7 1.1 0.6 | -55.4 -67.7 305 13 7 1.1 0.6 45000 -53.3 -63.9 325 24 12 1.1 0.6 | -53.8 -64.8 320 22 11 1.2 0.6 40000 -51.0 -59.8 335 26 14 1.5 0.8 | -51.8 -61.2 330 34 17 1.3 0.7 38000 -50.5 -58.9 340 29 15 -0.3 -0.1 | -51.1 -60.0 335 40 21 0.6 0.3 36000 -50.7 -59.3 340 36 19 -0.3 -0.2 | -50.8 -59.4 340 48 25 0.6 0.3 34000 -50.8 -59.4 345 43 22 2.1 1.1 | -50.3 -58.5 340 55 28 3.5 1.9 32000 -48.5 -55.3 350 45 23 3.8 2.1 | -47.8 -54.0 340 53 27 4.1 2.2 30000 -46.2 -51.2 350 48 24 5.6 3.1 | -45.3 -49.5 345 50 26 5.4 3.0 29000 -44.2 -47.6 355 46 24 6.7 3.7 | -43.7 -46.7 345 47 24 5.6 3.1 28000 -42.2 -44.0 355 45 23 6.7 3.7 | -42.0 -43.6 345 45 23 5.6 3.1 27000 -40.1 -40.2 355 44 23 6.7 3.7 | -40.3 -40.5 350 42 22 5.5 3.0 26000 -38.1 -36.6 355 42 22 6.8 3.7 | -38.2 -36.8 350 41 21 7.6 4.2 25000 -36.1 -33.0 355 39 20 6.8 3.7 | -35.9 -32.6 350 39 20 7.7 4.2 24000 -34.0 -29.2 355 36 19 6.8 3.7 | -33.6 -28.5 350 38 19 7.7 4.2 23000 -32.0 -25.6 355 34 17 7.0 3.8 | -31.4 -24.5 350 37 19 7.3 4.0 22000 -29.9 -21.8 355 33 17 7.0 3.8 | -28.6 -19.5 350 37 19 7.3 4.0 21000 -27.8 -18.0 355 31 16 6.9 3.8 | -26.4 -15.5 355 37 19 7.1 3.9 20000 -25.1 -13.2 355 30 15 7.3 4.0 | -24.3 -11.7 355 36 19 7.0 3.8 19500 -24.0 -11.2 355 29 15 7.3 4.0 | -23.3 -9.9 355 36 19 7.0 3.8 19000 -22.9 -9.2 355 29 15 7.3 4.0 | -22.2 -8.0 355 36 19 7.0 3.8 18500 -21.8 -7.2 355 29 15 7.0 3.8 | -21.2 -6.2 355 36 19 7.2 3.9 18000 -20.9 -5.6 355 28 15 5.9 3.2 | -20.1 -4.2 355 36 18 7.4 4.1 17500 -20.0 -4.0 355 28 14 6.0 3.3 | -18.9 -2.0 355 35 18 7.6 4.2 17000 -19.2 -2.6 355 28 14 4.6 2.5 | -18.0 -0.4 355 34 18 5.1 2.8 16500 -18.5 -1.3 350 28 14 4.6 2.5 | -17.2 1.0 355 33 17 5.4 3.0 16000 -17.8 -0.0 350 28 14 4.3 2.4 | -16.5 2.3 355 32 16 4.3 2.3 15500 -17.3 0.9 350 28 14 4.1 2.2 | -15.9 3.4 355 31 16 3.9 2.2 15000 -16.7 1.9 350 28 14 3.7 2.0 | -15.3 4.5 355 30 15 3.3 1.8 14500 -16.2 2.8 350 28 15 2.7 1.5 | -14.9 5.2 355 29 15 2.6 1.4 14000 -15.9 3.4 350 29 15 2.5 1.4 | -14.5 5.9 350 28 14 2.5 1.4 13500 -15.6 3.9 350 29 15 1.1 0.6 | -14.2 6.4 350 27 14 2.4 1.3 13000 -15.5 4.1 350 30 15 1.3 0.7 | -13.8 7.2 350 27 14 2.8 1.5 12500 -15.1 4.8 350 30 15 3.3 1.8 | -13.3 8.1 350 27 14 4.3 2.4 12000 -14.7 5.5 345 30 16 3.0 1.6 | -12.7 9.1 345 25 13 4.9 2.7 11750 -14.4 6.1 345 30 16 4.6 2.5 | -12.3 9.9 345 24 13 5.8 3.2 11500 -14.0 6.8 345 30 16 5.4 3.0 | -11.9 10.6 345 24 12 6.2 3.4 11250 -13.6 7.5 345 30 16 7.1 3.9 | -11.4 11.5 340 22 12 8.6 4.7 11000 -13.0 8.6 345 30 15 8.3 4.6 | -10.7 12.7 340 21 11 9.4 5.2 10750 -12.4 9.7 345 29 15 7.5 4.1 | -10.0 14.0 340 20 10 8.6 4.7 10500 -11.9 10.6 345 29 15 6.6 3.6 | -9.4 15.1 340 19 10 7.7 4.2 10250 -11.4 11.5 345 28 15 9.5 5.2 | -8.8 16.2 340 18 9 11.5 6.3 10000 -10.5 13.1 345 28 14 10.7 5.9 | -7.8 18.0 340 18 9 12.1 6.7 9750 -9.9 14.2 345 27 14 8.0 4.4 | -7.1 19.2 340 18 9 9.0 4.9 9500 -9.3 15.3 345 26 13 7.5 4.1 | -6.3 20.7 340 17 9 9.4 5.2 9250 -8.7 16.3 340 25 13 9.1 5.0 | -5.6 21.9 340 17 9 10.9 6.0 9000 -8.0 17.6 340 24 12 10.4 5.7 | -4.7 23.5 340 17 9 11.7 6.4 8750 -7.2 19.0 340 22 12 9.8 5.4 | -3.9 25.0 340 17 9 10.5 5.7 8500 -6.5 20.3 340 21 11 10.0 5.5 | -3.1 26.4 340 17 9 10.9 6.0 8250 -5.7 21.7 340 19 10 10.0 5.5 | -2.3 27.9 340 16 8 10.4 5.7 8000 -4.9 23.2 340 18 9 15.1 8.3 | -1.3 29.7 340 16 8 18.7 10.3 7750 -3.4 25.9 340 15 8 23.3 12.8 | 0.6 33.1 340 14 7 33.1 18.2 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 04/14/2018 at 1500 MDT | 04/14/2018 at 1800 MDT | CAPE... 0.0 LI... +5.3 | CAPE... 0.0 LI... +3.4 CINH... 0.0 K Index... -4.9 | CINH... 0.0 K Index... +2.9 | 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 -55.8 -68.4 310 17 9 1.6 0.9 | -58.0 -72.4 305 26 13 2.8 1.6 45000 -53.4 -64.1 325 28 14 0.9 0.5 | -53.8 -64.8 320 36 19 0.8 0.5 40000 -53.6 -64.5 330 40 20 -0.2 -0.1 | -55.3 -67.5 330 45 23 -1.0 -0.6 38000 -52.9 -63.2 330 46 24 2.4 1.3 | -54.2 -65.6 330 50 26 4.0 2.2 36000 -51.4 -60.5 335 54 28 2.5 1.3 | -51.8 -61.2 330 55 28 4.0 2.2 34000 -49.8 -57.6 335 61 31 5.4 3.0 | -49.1 -56.4 330 58 30 6.1 3.3 32000 -46.7 -52.1 335 55 28 5.1 2.8 | -45.6 -50.1 330 54 28 5.9 3.3 30000 -43.7 -46.7 335 50 26 4.8 2.6 | -42.1 -43.8 330 49 25 4.6 2.5 29000 -42.3 -44.1 335 46 24 4.7 2.6 | -40.7 -41.3 330 46 24 4.7 2.6 28000 -40.9 -41.6 335 43 22 4.7 2.6 | -39.3 -38.7 330 43 22 4.7 2.6 27000 -39.5 -39.1 335 39 20 4.3 2.4 | -37.9 -36.2 330 40 20 4.8 2.6 26000 -37.5 -35.5 335 37 19 7.6 4.2 | -36.0 -32.8 330 37 19 6.7 3.7 25000 -35.2 -31.4 335 35 18 7.5 4.1 | -34.0 -29.2 330 35 18 6.6 3.6 24000 -32.9 -27.2 340 33 17 7.6 4.2 | -32.0 -25.6 330 32 16 6.6 3.6 23000 -30.2 -22.4 340 31 16 7.2 4.0 | -29.4 -20.9 330 30 15 7.0 3.9 22000 -28.0 -18.4 340 30 15 7.2 4.0 | -27.3 -17.1 330 28 14 7.1 3.9 21000 -25.9 -14.6 345 29 15 7.0 3.9 | -25.2 -13.4 335 26 14 6.4 3.5 20000 -23.8 -10.8 345 29 15 7.0 3.8 | -23.4 -10.1 335 25 13 6.4 3.5 19500 -22.8 -9.0 345 28 15 7.0 3.8 | -22.4 -8.3 335 25 13 6.4 3.5 19000 -21.7 -7.1 345 28 14 7.0 3.8 | -21.5 -6.7 335 24 13 6.4 3.5 18500 -20.7 -5.3 345 28 14 7.0 3.9 | -20.5 -4.9 335 24 12 6.3 3.5 18000 -19.6 -3.3 345 28 14 7.1 3.9 | -19.6 -3.3 335 24 12 6.3 3.4 17500 -18.6 -1.5 345 27 14 7.1 3.9 | -18.6 -1.5 335 23 12 6.3 3.5 17000 -17.5 0.5 345 27 14 6.9 3.8 | -17.7 0.1 335 23 12 6.4 3.5 16500 -16.5 2.3 345 27 14 7.0 3.8 | -16.7 1.9 335 22 11 6.2 3.4 16000 -15.5 4.1 345 27 14 5.4 3.0 | -15.7 3.7 335 21 11 8.3 4.5 15500 -14.7 5.5 345 26 14 5.4 3.0 | -14.5 5.9 330 20 10 8.3 4.5 15000 -13.9 7.0 345 26 13 4.3 2.4 | -13.3 8.1 325 19 10 6.4 3.5 14500 -13.3 8.1 345 26 13 3.8 2.1 | -12.5 9.5 325 19 10 5.7 3.2 14000 -12.8 9.0 340 25 13 4.4 2.4 | -11.6 11.1 325 19 10 5.6 3.1 13500 -12.1 10.2 335 24 12 5.3 2.9 | -10.9 12.4 320 18 9 5.5 3.0 13000 -11.3 11.7 335 23 12 5.8 3.2 | -10.1 13.8 320 18 9 5.8 3.2 12500 -10.4 13.3 335 22 11 5.4 3.0 | -9.1 15.6 320 18 9 6.3 3.5 12000 -9.8 14.4 335 20 10 4.6 2.5 | -8.2 17.2 320 17 9 6.2 3.4 11750 -9.5 14.9 335 19 10 3.7 2.0 | -7.8 18.0 325 17 9 6.0 3.3 11500 -9.2 15.4 335 18 9 4.4 2.4 | -7.3 18.9 325 16 8 6.0 3.3 11250 -8.8 16.2 335 17 9 6.5 3.6 | -6.9 19.6 330 15 8 5.8 3.2 11000 -8.3 17.1 340 15 8 8.2 4.5 | -6.5 20.3 330 15 8 5.7 3.1 10750 -7.6 18.3 340 15 8 9.0 5.0 | -6.0 21.2 335 14 7 5.9 3.3 10500 -6.9 19.6 340 15 8 8.5 4.7 | -5.6 21.9 335 13 7 5.0 2.8 10250 -6.3 20.7 340 14 7 10.5 5.8 | -5.2 22.6 340 12 6 8.4 4.6 10000 -5.4 22.3 345 14 7 11.1 6.1 | -4.4 24.1 340 12 6 10.7 5.9 9750 -4.7 23.5 345 14 7 9.6 5.3 | -3.7 25.3 340 12 6 9.2 5.0 9500 -3.9 25.0 345 14 7 9.8 5.4 | -3.0 26.6 345 12 6 9.4 5.2 9250 -3.2 26.2 345 14 7 10.6 5.8 | -2.3 27.9 345 11 6 10.0 5.5 9000 -2.3 27.9 345 14 7 10.9 6.0 | -1.5 29.3 345 11 6 10.3 5.7 8750 -1.6 29.1 345 14 7 10.2 5.6 | -0.7 30.7 345 11 6 9.9 5.4 8500 -0.8 30.6 345 14 7 10.0 5.5 | -0.0 32.0 345 11 6 9.6 5.3 8250 -0.0 32.0 345 13 7 11.5 6.3 | 0.7 33.3 345 11 6 11.0 6.1 8000 1.1 34.0 345 13 7 19.7 10.8 | 1.7 35.1 345 11 5 14.6 8.0 7750 2.9 37.2 345 12 6 28.3 15.5 | 2.9 37.2 345 9 5 16.2 8.9 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 twice per day, once 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 rawinsonde observation and/or 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. 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. CIN (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
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