Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
533 UXUS97 KBOU 240005 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1804 MDT Thursday, May 23, 2024 This forecast is for Friday, May 24, 2024: If the trigger temperature of 56.0 F/13.3 C is reached...then Thermal Soaring Index....................... Good Maximum rate of lift........................ 754 ft/min (3.8 m/s) Maximum height of thermals.................. 15090 ft MSL (9807 ft AGL) Forecast maximum temperature................... 70.0 F/21.6 C Time of trigger temperature.................... 0945 MDT Time of overdevelopment........................ 1600 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 12916 ft MSL (7633 ft AGL) Thermal soaring outlook for Saturday 05/25..... 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 NVA Potential height of wave....................... 35076 ft MSL (29793 ft AGL) Wave soaring outlook for Saturday 05/25........ Poor Remarks... Sunrise/Sunset.................... 05:37:07 / 20:15:42 MDT Total possible sunshine........... 14 hr 38 min 35 sec (878 min 35 sec) Altitude of sun at 12:56:25 MDT... 71.18 degrees Upper air data from numerical model forecast valid on 05/24/2024 at 0600 MDT Freezing level.................. 9770 ft MSL (4487 ft AGL) Convective condensation level... 20374 ft MSL (15091 ft AGL) Lifted condensation level....... 18819 ft MSL (13536 ft AGL) Lifted index.................... +3.9 K index......................... -14.9 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 -54.8 -66.6 255 37 19 1.3 0.7 M M M M M 45000 -53.0 -63.4 260 63 32 -1.6 -0.9 M M M M M 40000 -55.0 -67.0 260 69 36 -1.4 -0.8 M M M M M 38000 -54.2 -65.6 260 72 37 3.3 1.8 M M M M M 36000 -52.3 -62.1 260 74 38 3.3 1.8 M M M M M 34000 -49.9 -57.8 260 74 38 6.7 3.7 M M M M M 32000 -45.9 -50.6 260 70 36 6.6 3.6 M M M M M 30000 -41.4 -42.5 260 65 34 7.4 4.1 34.8 94.7 10.3 M M 29000 -39.1 -38.4 260 63 33 7.4 4.1 33.8 92.9 9.7 M M 28000 -36.9 -34.4 260 62 32 7.4 4.1 33.0 91.3 9.1 M M 27000 -34.7 -30.5 260 60 31 7.3 4.0 32.2 89.9 8.6 M M 26000 -32.5 -26.5 265 59 30 7.3 4.0 31.1 88.0 7.9 M M 25000 -30.3 -22.5 265 57 29 7.3 4.0 30.2 86.4 7.2 M M 24000 -28.2 -18.8 265 56 29 7.4 4.1 29.4 84.9 6.7 M M 23000 -25.9 -14.6 265 53 27 7.6 4.2 28.5 83.3 6.0 M M 22000 -23.6 -10.5 265 51 26 7.6 4.2 27.7 81.9 5.5 M M 21000 -21.3 -6.3 265 48 25 7.6 3.8 27.0 80.7 5.0 M M 20000 -19.3 -2.7 265 43 22 6.7 3.7 25.9 78.6 4.0 M M 19500 -18.3 -0.9 265 40 21 6.7 3.7 25.3 77.6 3.6 M M 19000 -17.3 0.9 265 38 20 6.7 3.7 24.8 76.7 3.2 M M 18500 -16.3 2.7 265 35 18 7.0 3.8 24.3 75.8 2.8 M M 18000 -15.2 4.6 265 33 17 7.3 4.0 23.9 75.0 2.4 M M 17500 -14.1 6.6 265 31 16 7.3 4.0 23.5 74.3 2.0 M M 17000 -13.0 8.6 265 29 15 7.4 4.0 23.1 73.5 1.7 M M 16500 -11.9 10.6 265 27 14 7.4 4.0 22.7 72.8 1.3 M M 16000 -10.8 12.6 265 25 13 7.0 3.8 22.3 72.1 1.0 M M 15500 -9.3 15.3 265 22 11 6.9 3.8 21.5 70.7 0.3 M M 15000 -8.4 16.9 265 20 10 5.6 3.1 20.9 69.7 -0.2 737 3.7 14500 -7.6 18.3 270 18 9 5.5 3.0 20.2 68.4 -0.9 698 3.5 14000 -6.7 19.9 270 15 8 5.2 2.9 19.5 67.1 -1.6 659 3.3 13500 -6.0 21.2 270 13 7 5.1 2.8 18.7 65.7 -2.3 621 3.2 13000 -5.2 22.6 275 11 6 5.0 2.7 18.0 64.4 -3.0 584 3.0 12500 -4.5 23.9 280 8 4 4.9 2.7 17.2 62.9 -3.8 548 2.8 12000 -3.8 25.2 290 6 3 5.1 2.8 16.4 61.5 -4.5 511 2.6 11500 -3.0 26.6 305 5 2 5.5 3.0 15.7 60.2 -5.2 473 2.4 11000 -2.2 28.0 330 4 2 6.1 3.4 15.0 59.0 -5.9 434 2.2 10500 -1.2 29.8 335 4 2 7.6 4.2 14.5 58.2 -6.4 389 2.0 10250 -0.7 30.7 340 5 2 3.7 2.1 14.3 57.7 -6.7 366 1.9 10000 -0.5 31.1 340 5 2 5.0 2.8 13.7 56.7 -7.2 354 1.8 9750 0.1 32.2 335 5 3 9.9 5.4 13.7 56.6 -7.3 326 1.7 9500 0.8 33.4 330 5 3 8.7 4.8 13.6 56.5 -7.4 299 1.5 9250 1.5 34.7 330 6 3 8.6 4.7 13.5 56.3 -7.5 272 1.4 9000 2.1 35.8 325 6 3 7.2 3.9 13.4 56.1 -7.6 247 1.3 8750 2.6 36.7 320 8 4 7.1 3.9 13.2 55.7 -7.9 224 1.1 8500 3.2 37.8 320 10 5 8.1 4.4 13.0 55.4 -8.1 199 1.0 8250 3.7 38.7 315 12 6 6.3 3.4 12.8 55.1 -8.3 175 0.9 8000 4.1 39.4 310 14 7 3.6 2.0 12.4 54.4 -8.7 157 0.8 7750 4.3 39.7 310 17 9 2.1 1.2 11.9 53.4 -9.2 144 0.7 7500 4.4 39.9 305 19 10 1.5 0.8 11.3 52.3 -9.9 134 0.7 7250 4.4 39.9 305 20 10 0.8 0.4 10.6 51.1 -10.6 124 0.6 7000 4.4 39.9 300 19 10 -0.2 -0.1 9.9 49.8 -11.3 117 0.6 6750 4.4 39.9 300 18 9 0.6 0.3 9.2 48.5 -12.1 110 0.6 6500 4.5 40.1 300 15 8 3.0 1.6 8.5 47.4 -12.8 100 0.5 6250 4.8 40.6 295 12 6 5.3 2.9 8.1 46.6 -13.2 83 0.4 6000 5.2 41.4 295 10 5 5.8 3.2 7.8 46.1 -13.6 64 0.3 5750 5.6 42.1 295 7 4 5.1 2.8 7.5 45.5 -14.0 44 0.2 5500 5.9 42.6 280 4 2 2.2 1.2 7.1 44.7 -14.5 29 0.1 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 05/24/2024 at 0900 MDT | 05/24/2024 at 1200 MDT | CAPE... 0.0 LI... +6.8 | CAPE... 0.0 LI... +4.3 CINH... -0.1 K Index... -12.8 | CINH... -0.0 K Index... -4.6 | 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 -54.0 -65.2 265 46 23 1.1 0.6 | -54.0 -65.2 260 44 22 0.6 0.3 45000 -52.4 -62.3 260 61 31 -1.3 -0.7 | -53.2 -63.8 265 66 34 -1.1 -0.6 40000 -54.1 -65.4 260 72 37 -1.1 -0.6 | -54.7 -66.5 265 81 42 -1.0 -0.6 38000 -53.7 -64.7 265 74 38 1.8 1.0 | -54.1 -65.4 265 84 43 2.6 1.4 36000 -52.7 -62.9 265 74 38 1.8 1.0 | -52.5 -62.5 265 86 44 2.6 1.4 34000 -51.0 -59.8 265 74 38 7.9 4.3 | -49.9 -57.8 265 87 45 7.2 4.0 32000 -45.9 -50.6 265 72 37 7.6 4.2 | -45.5 -49.9 270 85 44 7.3 4.0 30000 -41.4 -42.5 265 70 36 7.3 4.0 | -41.0 -41.8 270 81 42 7.8 4.3 29000 -39.2 -38.6 265 68 35 7.3 4.0 | -38.7 -37.7 270 78 40 7.8 4.3 28000 -37.0 -34.6 265 65 34 7.3 4.0 | -36.3 -33.3 270 75 39 7.8 4.3 27000 -34.8 -30.6 265 63 32 7.0 3.9 | -34.1 -29.4 265 72 37 6.7 3.7 26000 -32.8 -27.0 265 60 31 6.9 3.8 | -32.2 -26.0 265 68 35 6.3 3.5 25000 -30.7 -23.3 265 58 30 6.9 3.8 | -30.3 -22.5 265 65 33 6.3 3.5 24000 -28.6 -19.5 265 55 28 7.1 3.9 | -28.4 -19.1 265 61 31 6.5 3.6 23000 -26.4 -15.5 265 53 27 7.5 4.1 | -26.4 -15.5 270 60 31 6.8 3.7 22000 -24.1 -11.4 265 52 27 7.5 4.1 | -24.3 -11.7 270 60 31 6.8 3.7 21000 -21.9 -7.4 265 50 26 6.9 3.8 | -22.3 -8.1 270 58 30 6.9 3.8 20000 -19.9 -3.8 265 46 24 6.6 3.6 | -20.2 -4.4 270 55 28 6.9 3.8 19500 -18.9 -2.0 270 44 23 6.6 3.6 | -19.2 -2.6 275 53 27 6.9 3.8 19000 -17.9 -0.2 270 42 22 6.6 3.6 | -18.1 -0.6 275 51 26 6.9 3.8 18500 -16.9 1.6 270 40 21 6.9 3.8 | -17.1 1.2 275 49 25 6.5 3.6 18000 -15.8 3.6 270 39 20 7.3 4.0 | -15.7 3.7 275 45 23 6.1 3.4 17500 -14.2 6.4 270 37 19 7.4 4.0 | -14.7 5.5 275 43 22 7.0 3.8 17000 -13.1 8.4 270 35 18 7.4 4.1 | -13.6 7.5 275 40 21 7.5 4.1 16500 -12.0 10.4 270 34 18 7.4 4.1 | -12.5 9.5 270 38 20 7.5 4.1 16000 -10.9 12.4 270 33 17 7.2 4.0 | -11.3 11.7 270 37 19 7.7 4.2 15500 -9.8 14.4 275 32 17 7.3 4.0 | -10.2 13.6 270 35 18 7.6 4.2 15000 -8.8 16.2 275 31 16 6.6 3.6 | -9.1 15.6 270 34 17 7.9 4.3 14500 -7.8 18.0 275 30 15 6.6 3.6 | -7.9 17.8 270 32 17 7.9 4.3 14000 -6.9 19.6 275 29 15 5.9 3.2 | -6.8 19.8 270 31 16 7.6 4.2 13500 -6.0 21.2 275 28 14 5.7 3.1 | -5.6 21.9 270 29 15 7.6 4.2 13000 -5.2 22.6 275 26 14 5.3 2.9 | -4.5 23.9 270 28 14 7.3 4.0 12500 -4.4 24.1 275 24 12 5.1 2.8 | -3.5 25.7 275 26 13 7.2 3.9 12000 -3.7 25.3 275 22 11 5.2 2.9 | -2.4 27.7 275 23 12 6.8 3.7 11500 -2.9 26.8 275 19 10 5.4 3.0 | -1.5 29.3 275 21 11 6.6 3.6 11000 -2.1 28.2 275 16 8 5.9 3.2 | -0.5 31.1 275 18 9 5.7 3.1 10500 -1.2 29.8 275 14 7 7.2 3.9 | 0.2 32.4 275 15 8 4.2 2.3 10250 -0.8 30.6 270 12 6 2.6 1.4 | 0.6 33.1 275 14 7 8.8 4.8 10000 -0.7 30.7 270 13 7 3.6 2.0 | 1.4 34.5 275 11 6 10.1 5.5 9750 -0.1 31.8 275 11 6 9.0 4.9 | 2.0 35.6 270 9 5 6.2 3.4 9500 0.5 32.9 275 9 5 7.6 4.2 | 2.5 36.5 265 8 4 7.6 4.2 9250 1.0 33.8 275 8 4 7.8 4.3 | 3.0 37.4 260 6 3 5.8 3.2 9000 1.6 34.9 275 7 3 6.6 3.6 | 3.4 38.1 250 4 2 6.2 3.4 8750 2.0 35.6 280 6 3 6.1 3.3 | 4.0 39.2 240 4 2 8.8 4.8 8500 2.5 36.5 280 5 3 6.3 3.5 | 4.7 40.5 220 3 1 9.1 5.0 8250 3.0 37.4 285 4 2 6.1 3.3 | 5.3 41.5 195 2 1 8.6 4.7 8000 3.4 38.1 290 4 2 5.6 3.1 | 5.9 42.6 175 3 1 8.6 4.7 7750 3.8 38.8 290 4 2 4.5 2.5 | 6.6 43.9 165 3 1 9.9 5.4 7500 4.0 39.2 310 5 2 3.7 2.0 | 7.4 45.3 160 3 1 10.5 5.8 7250 4.3 39.7 320 5 3 2.7 1.5 | 8.1 46.6 160 2 1 8.8 4.8 7000 4.3 39.7 325 4 2 0.3 0.1 | 8.7 47.7 155 3 1 7.4 4.1 6750 4.5 40.1 335 2 1 6.7 3.7 | 9.4 48.9 155 3 2 11.5 6.3 6500 5.2 41.4 350 1 1 11.4 6.3 | 10.4 50.7 150 3 1 12.9 7.1 6250 6.0 42.8 010 1 0 9.4 5.1 | 11.2 52.2 145 3 1 10.5 5.8 6000 6.7 44.1 025 1 0 8.9 4.9 | 12.0 53.6 145 3 1 9.9 5.4 5750 7.4 45.3 055 1 0 11.7 6.4 | 12.8 55.0 145 3 2 12.2 6.7 5500 8.6 47.5 020 1 0 21.1 11.6 | 14.0 57.2 145 3 1 23.3 12.8 05/24/2024 at 1500 MDT | 05/24/2024 at 1800 MDT | CAPE... 0.0 LI... +2.1 | CAPE... 0.0 LI... +1.2 CINH... 0.0 K Index... +9.9 | CINH... 0.0 K Index... +15.7 | 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 -54.3 -65.7 260 48 25 1.4 0.7 | -55.5 -67.9 265 49 25 1.2 0.6 45000 -52.6 -62.7 265 67 34 -1.7 -0.9 | -54.0 -65.2 270 71 37 -1.3 -0.7 40000 -54.9 -66.8 265 84 43 -1.6 -0.9 | -55.8 -68.4 265 88 45 -1.3 -0.7 38000 -54.3 -65.7 265 87 45 2.6 1.4 | -54.9 -66.8 265 89 46 3.1 1.7 36000 -52.7 -62.9 265 88 45 2.6 1.4 | -53.0 -63.4 265 87 45 3.1 1.7 34000 -49.9 -57.8 270 87 45 7.5 4.1 | -49.9 -57.8 265 84 43 7.7 4.2 32000 -45.4 -49.7 270 85 44 7.5 4.1 | -45.3 -49.5 265 80 41 7.7 4.2 30000 -40.7 -41.3 270 82 42 8.2 4.5 | -40.6 -41.1 265 75 39 8.3 4.5 29000 -38.3 -36.9 270 79 41 8.2 4.5 | -38.1 -36.6 265 72 37 8.3 4.5 28000 -35.8 -32.4 270 77 39 8.2 4.5 | -35.6 -32.1 265 69 35 8.3 4.5 27000 -33.5 -28.3 270 74 38 6.1 3.3 | -33.2 -27.8 265 66 34 7.5 4.1 26000 -31.8 -25.2 270 71 36 5.8 3.2 | -31.0 -23.8 265 65 33 7.5 4.1 25000 -30.0 -22.0 265 68 35 5.8 3.2 | -28.7 -19.7 265 63 33 7.5 4.1 24000 -28.3 -18.9 265 64 33 6.7 3.7 | -26.5 -15.7 265 62 32 6.2 3.4 23000 -26.1 -15.0 265 61 31 7.7 4.2 | -24.9 -12.8 265 56 29 5.4 2.9 22000 -23.8 -10.8 265 57 30 7.7 4.2 | -23.3 -9.9 265 51 26 5.3 2.9 21000 -21.6 -6.9 260 54 28 6.3 3.5 | -21.6 -6.9 265 46 24 8.1 4.5 20000 -19.7 -3.5 265 50 26 6.1 3.4 | -19.1 -2.4 260 45 23 8.3 4.5 19500 -18.8 -1.8 270 48 25 6.1 3.4 | -17.9 -0.2 260 44 23 8.3 4.5 19000 -17.9 -0.2 270 46 24 6.1 3.4 | -16.1 3.0 260 43 22 8.3 4.6 18500 -17.0 1.4 270 44 23 6.3 3.4 | -14.8 5.4 260 43 22 8.7 4.8 18000 -16.0 3.2 270 42 22 6.4 3.5 | -13.5 7.7 260 43 22 8.7 4.8 17500 -14.5 5.9 265 38 20 7.7 4.2 | -12.3 9.9 260 42 22 8.0 4.4 17000 -13.3 8.1 265 35 18 8.4 4.6 | -11.2 11.8 260 42 22 7.7 4.2 16500 -12.0 10.4 260 31 16 8.4 4.6 | -10.0 14.0 260 42 22 7.6 4.2 16000 -10.7 12.7 255 29 15 8.6 4.7 | -9.0 15.8 260 41 21 7.1 3.9 15500 -9.4 15.1 260 27 14 8.6 4.7 | -7.9 17.8 260 40 20 7.1 3.9 15000 -8.1 17.4 260 25 13 8.9 4.9 | -6.9 19.6 260 37 19 6.9 3.8 14500 -6.8 19.8 260 24 12 8.8 4.9 | -5.8 21.6 260 35 18 7.0 3.8 14000 -5.5 22.1 260 22 11 8.7 4.8 | -4.8 23.4 260 31 16 6.8 3.7 13500 -4.2 24.4 255 21 11 8.8 4.8 | -3.8 25.2 255 28 14 6.8 3.7 13000 -3.0 26.6 250 19 10 7.4 4.1 | -2.8 27.0 255 24 12 7.4 4.0 12500 -2.0 28.4 240 17 9 6.9 3.8 | -1.6 29.1 255 21 11 7.7 4.2 12000 -0.9 30.4 230 15 8 7.2 4.0 | -0.4 31.3 250 17 9 8.3 4.5 11500 0.1 32.2 215 14 7 7.4 4.1 | 0.9 33.6 240 14 7 8.7 4.8 11000 1.2 34.2 200 12 6 6.5 3.5 | 2.3 36.1 230 12 6 8.5 4.7 10500 2.1 35.8 185 10 5 5.5 3.0 | 3.5 38.3 225 10 5 8.0 4.4 10250 2.5 36.5 175 9 5 7.7 4.3 | 4.1 39.4 220 10 5 9.8 5.4 10000 3.2 37.8 170 9 5 9.6 5.3 | 4.9 40.8 210 9 5 10.5 5.7 9750 3.9 39.0 165 9 4 8.6 4.7 | 5.6 42.1 205 9 5 9.3 5.1 9500 4.5 40.1 165 8 4 9.0 4.9 | 6.3 43.3 200 8 4 9.3 5.1 9250 5.2 41.4 160 8 4 8.5 4.7 | 7.0 44.6 195 8 4 10.6 5.8 9000 5.8 42.4 160 8 4 9.2 5.0 | 7.8 46.0 190 8 4 9.8 5.4 8750 6.6 43.9 160 8 4 10.2 5.6 | 8.4 47.1 185 8 4 8.1 4.4 8500 7.3 45.1 155 8 4 9.7 5.3 | 9.0 48.2 180 7 4 8.0 4.4 8250 8.1 46.6 155 8 4 10.9 6.0 | 9.6 49.3 175 7 4 10.1 5.6 8000 8.9 48.0 155 7 4 11.6 6.4 | 10.5 50.9 170 7 4 12.0 6.6 7750 9.7 49.5 155 7 4 10.1 5.6 | 11.3 52.3 165 7 3 9.5 5.2 7500 10.5 50.9 155 7 4 9.6 5.3 | 11.9 53.4 165 6 3 8.0 4.4 7250 11.2 52.2 155 7 4 10.0 5.5 | 12.6 54.7 160 6 3 10.1 5.5 7000 12.0 53.6 155 7 4 10.2 5.6 | 13.4 56.1 160 6 3 11.7 6.4 6750 12.7 54.9 155 7 3 9.2 5.1 | 14.2 57.6 155 6 3 8.7 4.8 6500 13.4 56.1 155 6 3 9.6 5.3 | 14.8 58.6 155 5 3 7.8 4.3 6250 14.2 57.6 155 6 3 11.4 6.3 | 15.5 59.9 155 5 3 10.2 5.6 6000 15.0 59.0 155 6 3 11.9 6.5 | 16.3 61.3 155 5 3 11.5 6.3 5750 15.9 60.6 155 6 3 11.0 6.0 | 17.1 62.8 150 5 2 9.4 5.2 5500 16.9 62.4 155 6 3 17.2 9.4 | 17.7 63.9 150 4 2 9.8 5.4 ________________________________________________________________________________ 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: 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. CINH (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