Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
309 UXUS97 KBOU 271225 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0624 MDT Thursday, June 27, 2024 This forecast is for Thursday, June 27, 2024: If the trigger temperature of 83.4 F/28.5 C is reached...then Thermal Soaring Index....................... Good Maximum rate of lift........................ 747 ft/min (3.8 m/s) Maximum height of thermals.................. 16074 ft MSL (10737 ft AGL) Forecast maximum temperature................... 92.0 F/33.8 C Time of trigger temperature.................... 1000 MDT Time of overdevelopment........................ 1200 MDT Middle/high clouds during soaring window....... Broken/overcast opaque middle Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 11876 ft MSL (6539 ft AGL) Thermal soaring outlook for Friday 06/28....... 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....................... 41281 ft MSL (35944 ft AGL) Wave soaring outlook for Friday 06/28.......... Fair Remarks... Sunrise/Sunset.................... 05:33:46 / 20:31:43 MDT Total possible sunshine........... 14 hr 57 min 57 sec (897 min 57 sec) Altitude of sun at 13:02:44 MDT... 73.50 degrees Upper air data from numerical model forecast valid on 06/27/2024 at 0600 MDT Freezing level.................. 16624 ft MSL (11287 ft AGL) Convective condensation level... 14278 ft MSL (8941 ft AGL) Lifted condensation level....... 15048 ft MSL (9711 ft AGL) Lifted index.................... -3.4 K index......................... +28.6 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 -65.5 -85.9 255 44 22 2.4 1.3 M M M M M 45000 -59.4 -74.9 250 57 29 6.9 3.8 M M M M M 40000 -48.9 -56.0 250 61 32 7.4 4.0 M M M M M 38000 -44.5 -48.1 255 57 30 7.4 4.0 M M M M M 36000 -40.1 -40.2 260 54 28 7.4 4.1 M M M M M 34000 -35.0 -31.0 260 45 23 7.4 4.1 M M M M M 32000 -30.6 -23.1 260 37 19 8.1 4.4 M M M M M 30000 -26.3 -15.3 260 33 17 7.1 3.9 49.9 121.8 12.6 M M 29000 -24.2 -11.6 260 31 16 7.1 3.9 48.9 120.1 12.0 M M 28000 -22.1 -7.8 260 29 15 6.7 3.7 48.0 118.4 11.4 M M 27000 -20.1 -4.2 260 29 15 6.7 3.7 46.7 116.1 10.5 M M 26000 -18.1 -0.6 260 28 14 6.7 3.7 45.6 114.0 9.6 M M 25000 -16.1 3.0 260 27 14 6.7 3.7 44.5 112.2 8.9 M M 24000 -14.1 6.6 265 27 14 7.0 3.8 43.4 110.1 8.0 M M 23000 -12.1 10.2 265 26 13 7.0 3.8 42.4 108.3 7.2 M M 22000 -10.0 14.0 270 25 13 6.8 3.7 41.5 106.7 6.5 M M 21000 -8.3 17.1 270 24 12 6.0 3.3 40.1 104.2 5.3 M M 20000 -6.5 20.3 275 21 11 6.0 3.3 38.8 101.8 4.2 M M 19500 -5.7 21.7 275 20 11 6.0 3.3 38.2 100.7 3.6 M M 19000 -4.3 24.3 275 19 10 6.6 3.6 37.3 99.2 2.9 M M 18500 -3.4 25.9 275 17 9 6.6 3.6 36.8 98.2 2.3 M M 18000 -2.4 27.7 270 16 8 6.5 3.6 36.2 97.2 1.8 M M 17500 -1.5 29.3 270 15 8 6.5 3.6 35.7 96.2 1.3 M M 17000 -0.6 30.9 270 15 8 6.6 3.6 35.1 95.2 0.8 M M 16500 0.4 32.7 270 14 7 6.9 3.8 34.6 94.3 0.3 M M 16000 1.4 34.5 270 13 7 6.9 3.8 34.1 93.5 -0.1 933 4.7 15500 2.4 36.3 270 13 7 7.1 3.9 33.7 92.6 -0.6 889 4.5 15000 3.4 38.1 270 12 6 7.1 3.9 33.2 91.8 -1.1 844 4.3 14500 4.4 39.9 270 12 6 7.7 4.2 32.8 91.1 -1.5 798 4.1 14000 5.6 42.1 275 11 6 8.1 4.4 32.5 90.6 -1.8 748 3.8 13500 6.8 44.2 275 11 6 8.1 4.5 32.3 90.1 -2.1 698 3.5 13000 8.0 46.4 280 11 6 8.2 4.5 32.0 89.6 -2.4 648 3.3 12500 9.2 48.6 285 11 6 8.2 4.5 31.8 89.2 -2.7 597 3.0 12000 10.4 50.7 290 11 6 8.1 4.5 31.5 88.7 -2.9 547 2.8 11500 11.5 52.7 290 11 6 8.2 4.5 31.3 88.3 -3.2 497 2.5 11000 12.6 54.7 295 12 6 6.4 3.5 30.8 87.5 -3.7 451 2.3 10500 13.5 56.3 295 12 6 11.0 6.0 30.3 86.5 -4.2 408 2.1 10250 14.5 58.1 295 13 7 11.9 6.5 30.6 87.1 -3.9 370 1.9 10000 15.1 59.2 295 13 7 6.7 3.7 30.5 86.8 -4.1 346 1.8 9750 15.6 60.1 290 13 7 8.0 4.4 30.3 86.6 -4.3 322 1.6 9500 16.2 61.2 290 14 7 7.9 4.3 30.2 86.3 -4.4 297 1.5 9250 16.7 62.1 290 14 7 5.0 2.8 30.0 85.9 -4.7 274 1.4 9000 17.0 62.6 295 14 7 5.4 3.0 29.5 85.1 -5.1 258 1.3 8750 17.6 63.7 290 14 7 8.1 4.5 29.4 84.8 -5.3 235 1.2 8500 18.1 64.6 290 14 7 7.3 4.0 29.2 84.5 -5.5 211 1.1 8250 18.6 65.5 290 14 7 6.4 3.5 29.0 84.2 -5.7 189 1.0 8000 19.0 66.2 290 14 7 5.0 2.7 28.7 83.6 -6.1 170 0.9 7750 19.3 66.7 290 13 7 4.8 2.6 28.3 82.9 -6.5 153 0.8 7500 19.6 67.3 285 12 6 4.1 2.2 27.9 82.2 -7.0 136 0.7 7250 19.8 67.6 285 12 6 2.3 1.3 27.4 81.3 -7.5 122 0.6 7000 19.9 67.8 285 11 6 1.4 0.8 26.8 80.2 -8.1 112 0.6 6750 20.0 68.0 285 10 5 1.4 0.8 26.1 79.1 -8.8 102 0.5 6500 20.0 68.0 280 8 4 0.4 0.2 25.5 77.9 -9.6 95 0.5 6250 19.9 67.8 280 7 3 -0.5 -0.3 24.7 76.5 -10.4 90 0.5 6000 19.8 67.6 280 6 3 -0.0 -0.0 24.0 75.1 -11.3 86 0.4 5750 19.7 67.5 280 5 2 -1.7 -0.9 23.2 73.8 -12.1 82 0.4 5500 19.2 66.6 245 3 2 -9.7 -5.3 22.1 71.7 -13.4 88 0.4 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 06/27/2024 at 0900 MDT | 06/27/2024 at 1200 MDT | CAPE... +416.6 LI... -1.2 | CAPE... +569.1 LI... -2.8 CINH... -113.1 K Index... +28.8 | CINH... -23.7 K Index... +29.6 | 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 -64.9 -84.8 260 42 21 1.9 1.1 | -63.9 -83.0 255 41 21 3.2 1.7 45000 -59.4 -74.9 255 58 30 6.7 3.7 | -58.1 -72.6 255 60 31 5.2 2.9 40000 -49.2 -56.6 250 66 34 7.5 4.1 | -49.7 -57.5 245 79 41 8.0 4.4 38000 -44.7 -48.5 245 62 32 7.5 4.1 | -44.9 -48.8 245 74 38 8.0 4.4 36000 -40.2 -40.4 245 59 30 7.4 4.1 | -40.1 -40.2 240 69 36 8.1 4.4 34000 -35.5 -31.9 245 51 26 6.9 3.8 | -35.7 -32.3 240 58 30 6.4 3.5 32000 -31.4 -24.5 245 43 22 7.5 4.1 | -31.8 -25.2 235 48 25 6.8 3.7 30000 -27.2 -17.0 245 36 19 7.1 3.9 | -27.7 -17.9 240 42 22 7.1 3.9 29000 -25.1 -13.2 245 33 17 7.1 3.9 | -25.6 -14.1 240 40 20 7.1 3.9 28000 -23.0 -9.4 250 30 16 7.0 3.8 | -23.5 -10.3 245 37 19 6.8 3.7 27000 -21.0 -5.8 250 29 15 7.0 3.8 | -21.5 -6.7 245 35 18 6.7 3.7 26000 -18.9 -2.0 255 28 14 7.0 3.9 | -19.5 -3.1 245 33 17 6.8 3.7 25000 -16.8 1.8 260 27 14 7.1 3.9 | -17.5 0.5 245 31 16 6.8 3.7 24000 -14.7 5.5 260 27 14 7.3 4.0 | -15.5 4.1 245 30 16 6.7 3.7 23000 -12.5 9.5 265 27 14 7.3 4.0 | -13.6 7.5 250 30 15 6.7 3.7 22000 -10.4 13.3 265 27 14 7.2 3.9 | -11.6 11.1 250 30 15 6.7 3.7 21000 -8.5 16.7 265 26 13 6.3 3.5 | -9.6 14.7 250 28 15 6.9 3.8 20000 -6.7 19.9 265 25 13 6.4 3.5 | -7.6 18.3 255 27 14 6.9 3.8 19500 -5.8 21.6 265 24 12 6.5 3.5 | -6.6 20.1 255 26 14 6.9 3.8 19000 -4.5 23.9 265 23 12 5.6 3.1 | -5.6 21.9 260 26 13 7.4 4.1 18500 -3.7 25.3 260 22 11 5.7 3.1 | -4.5 23.9 260 25 13 7.5 4.1 18000 -2.8 27.0 260 20 10 6.2 3.4 | -2.8 27.0 260 24 12 7.8 4.3 17500 -1.9 28.6 255 19 10 6.3 3.5 | -1.7 28.9 265 23 12 7.9 4.3 17000 -1.0 30.2 255 18 9 6.5 3.5 | -0.5 31.1 265 23 12 7.9 4.3 16500 -0.0 32.0 250 17 9 7.2 4.0 | 0.6 33.1 270 23 12 7.9 4.3 16000 1.0 33.8 250 16 8 7.2 3.9 | 1.8 35.2 270 23 12 7.9 4.3 15500 2.1 35.8 250 15 8 7.7 4.2 | 2.9 37.2 275 23 12 7.6 4.1 15000 3.2 37.8 250 15 7 7.7 4.3 | 4.0 39.2 275 23 12 7.5 4.1 14500 4.3 39.7 255 14 7 8.0 4.4 | 5.1 41.2 275 23 12 7.3 4.0 14000 5.5 41.9 255 13 7 8.1 4.5 | 6.1 43.0 280 24 12 7.2 3.9 13500 6.7 44.1 260 13 7 8.2 4.5 | 7.1 44.8 280 24 12 7.2 4.0 13000 7.9 46.2 265 13 7 8.2 4.5 | 8.1 46.6 280 24 12 7.4 4.1 12500 9.1 48.4 270 13 7 8.2 4.5 | 9.2 48.6 280 24 12 7.5 4.1 12000 10.4 50.7 275 14 7 8.6 4.7 | 10.3 50.5 280 23 12 8.1 4.4 11500 11.6 52.9 280 15 8 8.7 4.8 | 11.4 52.5 280 21 11 8.1 4.5 11000 12.7 54.9 285 17 9 6.8 3.7 | 12.4 54.3 280 19 10 6.8 3.7 10500 13.7 56.7 285 18 9 10.1 5.5 | 13.4 56.1 275 17 9 11.0 6.0 10250 14.6 58.3 285 20 10 10.6 5.8 | 14.4 57.9 275 16 8 12.4 6.8 10000 15.1 59.2 285 20 11 6.8 3.7 | 15.1 59.2 280 15 8 7.9 4.3 9750 15.7 60.3 285 21 11 7.8 4.3 | 15.7 60.3 280 14 7 9.1 5.0 9500 16.2 61.2 285 22 11 7.6 4.2 | 16.4 61.5 280 13 7 8.8 4.8 9250 16.8 62.2 285 22 11 6.8 3.7 | 17.0 62.6 280 12 6 7.2 3.9 9000 17.2 63.0 285 22 11 6.8 3.7 | 17.5 63.5 280 11 6 8.8 4.8 8750 17.7 63.9 285 21 11 7.6 4.2 | 18.3 64.9 280 11 6 11.2 6.1 8500 18.3 64.9 285 21 11 7.4 4.1 | 19.1 66.4 285 11 5 10.7 5.8 8250 18.8 65.8 285 21 11 7.3 4.0 | 19.8 67.6 285 10 5 8.9 4.9 8000 19.3 66.7 285 20 10 6.9 3.8 | 20.5 68.9 285 10 5 9.2 5.0 7750 19.8 67.6 285 19 10 6.9 3.8 | 21.2 70.2 285 10 5 11.2 6.1 7500 20.3 68.5 285 18 9 6.4 3.5 | 22.0 71.6 285 9 5 10.2 5.6 7250 20.7 69.3 285 16 8 4.4 2.4 | 22.7 72.9 285 9 5 8.3 4.5 7000 21.0 69.8 285 15 8 4.2 2.3 | 23.3 73.9 285 9 5 8.5 4.7 6750 21.3 70.3 285 13 7 6.7 3.7 | 24.1 75.4 290 9 5 11.9 6.5 6500 21.9 71.4 290 11 6 6.8 3.7 | 25.0 77.0 290 8 4 11.9 6.6 6250 22.3 72.1 285 8 4 5.6 3.1 | 25.8 78.4 290 8 4 10.4 5.7 6000 22.6 72.7 275 6 3 5.4 3.0 | 26.6 79.9 290 8 4 10.3 5.7 5750 23.0 73.4 260 4 2 7.8 4.3 | 27.4 81.3 290 8 4 10.9 6.0 5500 23.7 74.7 255 3 2 15.6 8.6 | 28.4 83.1 290 7 4 20.1 11.0 06/27/2024 at 1500 MDT | 06/27/2024 at 1800 MDT | CAPE... +679.9 LI... -2.5 | CAPE... +401.5 LI... -1.8 CINH... -4.2 K Index... +33.1 | CINH... -17.7 K Index... +31.6 | 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 -64.2 -83.6 245 44 23 3.9 2.1 | -64.4 -83.9 255 42 22 3.0 1.6 45000 -57.5 -71.5 250 63 33 4.9 2.7 | -58.1 -72.6 250 53 27 5.8 3.2 40000 -49.6 -57.3 245 86 44 8.0 4.4 | -49.1 -56.4 245 77 40 7.3 4.0 38000 -44.8 -48.6 245 83 43 7.9 4.4 | -44.7 -48.5 250 76 39 7.3 4.0 36000 -40.0 -40.0 245 80 41 8.2 4.5 | -40.4 -40.7 250 74 38 7.5 4.1 34000 -36.2 -33.2 240 68 35 5.5 3.0 | -36.9 -34.4 250 64 33 5.6 3.1 32000 -32.8 -27.0 235 57 29 6.2 3.4 | -33.1 -27.6 245 51 26 6.1 3.4 30000 -28.7 -19.7 240 49 25 7.1 3.9 | -28.8 -19.8 245 46 24 7.4 4.0 29000 -26.6 -15.9 240 45 23 7.1 3.9 | -26.6 -15.9 245 45 23 7.4 4.1 28000 -24.4 -11.9 245 42 21 7.2 4.0 | -24.4 -11.9 245 43 22 7.3 4.0 27000 -22.3 -8.1 250 38 20 7.2 4.0 | -22.3 -8.1 245 39 20 7.2 4.0 26000 -20.2 -4.4 250 35 18 7.3 4.0 | -20.1 -4.2 250 35 18 7.3 4.0 25000 -18.0 -0.4 255 32 16 7.3 4.0 | -18.0 -0.4 250 31 16 7.3 4.0 24000 -15.8 3.6 260 30 16 7.3 4.0 | -15.8 3.6 250 30 15 7.4 4.1 23000 -13.7 7.3 260 29 15 7.4 4.0 | -13.6 7.5 250 29 15 7.4 4.1 22000 -11.5 11.3 265 28 15 7.3 4.0 | -11.4 11.5 255 28 15 7.4 4.0 21000 -9.5 14.9 265 28 14 7.0 3.8 | -9.4 15.1 255 27 14 6.8 3.7 20000 -7.4 18.7 265 27 14 7.0 3.9 | -7.4 18.7 260 25 13 6.9 3.8 19500 -6.4 20.5 265 27 14 7.0 3.9 | -6.4 20.5 260 25 13 6.9 3.8 19000 -5.4 22.3 265 27 14 7.3 4.0 | -5.5 22.1 260 24 12 6.7 3.7 18500 -4.4 24.1 270 27 14 7.3 4.0 | -4.5 23.9 260 23 12 6.7 3.7 18000 -2.8 27.0 270 28 14 7.3 4.0 | -3.6 25.5 265 22 11 6.9 3.8 17500 -1.7 28.9 270 28 14 7.3 4.0 | -2.6 27.3 265 22 11 7.4 4.1 17000 -0.7 30.7 270 28 14 7.4 4.0 | -1.0 30.2 270 21 11 7.5 4.1 16500 0.4 32.7 270 27 14 7.5 4.1 | 0.1 32.2 270 20 10 7.7 4.2 16000 1.4 34.5 270 25 13 7.5 4.1 | 1.2 34.2 270 20 10 7.6 4.2 15500 2.5 36.5 265 24 12 8.2 4.5 | 2.4 36.3 270 19 10 8.8 4.8 15000 3.7 38.7 265 22 11 8.2 4.5 | 3.7 38.7 270 18 9 8.9 4.9 14500 4.9 40.8 265 21 11 8.7 4.8 | 5.0 41.0 270 17 9 9.1 5.0 14000 6.2 43.2 270 19 10 9.1 5.0 | 6.4 43.5 275 17 9 9.4 5.1 13500 7.6 45.7 270 18 9 9.2 5.0 | 7.8 46.0 275 17 9 9.4 5.1 13000 8.9 48.0 270 17 9 9.4 5.2 | 9.2 48.6 275 16 8 9.3 5.1 12500 10.3 50.5 270 15 8 9.4 5.2 | 10.5 50.9 275 16 8 9.3 5.1 12000 11.7 53.1 275 14 7 9.3 5.1 | 11.9 53.4 280 16 8 9.0 4.9 11500 13.1 55.6 275 13 7 9.4 5.2 | 13.2 55.8 280 16 8 9.2 5.0 11000 14.3 57.7 275 13 7 8.1 4.5 | 14.5 58.1 280 15 8 7.8 4.3 10500 15.5 59.9 280 12 6 12.0 6.6 | 15.6 60.1 285 15 8 10.9 6.0 10250 16.6 61.9 280 12 6 13.4 7.3 | 16.6 61.9 285 15 8 12.3 6.7 10000 17.3 63.1 280 11 6 9.1 5.0 | 17.3 63.1 285 15 8 9.1 5.0 9750 18.1 64.6 280 11 6 9.9 5.4 | 18.0 64.4 285 15 8 9.6 5.2 9500 18.8 65.8 280 11 6 10.0 5.5 | 18.7 65.7 285 15 8 9.7 5.3 9250 19.5 67.1 280 11 5 8.9 4.9 | 19.4 66.9 285 15 8 8.8 4.8 9000 20.2 68.4 285 11 5 9.3 5.1 | 20.1 68.2 285 15 8 9.2 5.1 8750 20.9 69.6 285 10 5 10.7 5.9 | 20.8 69.4 285 15 8 10.4 5.7 8500 21.7 71.1 285 10 5 10.5 5.8 | 21.6 70.9 285 15 8 10.3 5.7 8250 22.5 72.5 285 10 5 9.8 5.4 | 22.3 72.1 285 15 8 9.5 5.2 8000 23.2 73.8 290 10 5 9.6 5.3 | 23.0 73.4 285 16 8 9.5 5.2 7750 23.9 75.0 285 10 5 10.2 5.6 | 23.7 74.7 285 15 8 10.4 5.7 7500 24.7 76.5 285 9 5 10.1 5.5 | 24.5 76.1 285 14 7 10.2 5.6 7250 25.4 77.7 285 9 5 8.3 4.6 | 25.2 77.4 285 14 7 8.4 4.6 7000 26.0 78.8 290 9 5 8.6 4.7 | 25.8 78.4 285 15 8 8.3 4.6 6750 26.8 80.2 290 9 5 11.7 6.4 | 26.5 79.7 285 15 8 11.1 6.1 6500 27.6 81.7 290 9 4 12.0 6.6 | 27.4 81.3 285 14 7 11.3 6.2 6250 28.5 83.3 290 8 4 10.8 6.0 | 28.2 82.8 285 13 7 10.3 5.7 6000 29.3 84.7 290 8 4 11.1 6.1 | 29.0 84.2 285 14 7 10.3 5.6 5750 30.1 86.2 295 8 4 9.2 5.0 | 29.7 85.5 285 14 7 9.7 5.3 5500 30.9 87.6 290 7 4 15.7 8.6 | 30.5 86.9 285 11 6 12.4 6.8 ________________________________________________________________________________ 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