Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
940 UXUS97 KBOU 261219 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0618 MDT Wednesday, June 26, 2024 This forecast is for Wednesday, June 26, 2024: If the trigger temperature of 85.6 F/29.8 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1093 ft/min (5.6 m/s) Maximum height of thermals.................. 17024 ft MSL (11672 ft AGL) Forecast maximum temperature................... 92.0 F/33.8 C Time of trigger temperature.................... 1145 MDT Time of overdevelopment........................ 1500 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 10273 ft MSL (4921 ft AGL) Thermal soaring outlook for Thursday 06/27..... Excellent 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)................ Neither Potential height of wave....................... 16903 ft MSL (11551 ft AGL) Wave soaring outlook for Thursday 06/27........ Poor Remarks... Sunrise/Sunset.................... 05:33:22 / 20:31:42 MDT Total possible sunshine........... 14 hr 58 min 20 sec (898 min 20 sec) Altitude of sun at 13:02:32 MDT... 73.54 degrees Upper air data from numerical model forecast valid on 06/26/2024 at 0600 MDT Freezing level.................. 16380 ft MSL (11028 ft AGL) Convective condensation level... 17515 ft MSL (12163 ft AGL) Lifted condensation level....... 17487 ft MSL (12135 ft AGL) Lifted index.................... -1.0 K index......................... +21.8 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 -64.5 -84.1 270 25 13 2.8 1.5 M M M M M 45000 -57.4 -71.3 275 38 20 7.1 3.9 M M M M M 40000 -47.0 -52.6 280 51 26 6.4 3.5 M M M M M 38000 -43.2 -45.8 285 57 29 6.4 3.5 M M M M M 36000 -39.3 -38.7 285 63 32 6.5 3.5 M M M M M 34000 -35.5 -31.9 290 57 29 6.5 3.6 M M M M M 32000 -31.1 -24.0 295 50 26 6.8 3.7 M M M M M 30000 -27.2 -17.0 300 39 20 6.5 3.5 48.8 119.8 11.8 M M 29000 -25.3 -13.5 300 34 17 6.5 3.5 47.6 117.7 11.0 M M 28000 -23.4 -10.1 305 29 15 5.9 3.2 46.3 115.4 10.2 M M 27000 -21.6 -6.9 305 26 13 6.0 3.3 44.8 112.6 9.1 M M 26000 -19.8 -3.6 305 23 12 6.0 3.3 43.4 110.1 8.0 M M 25000 -18.0 -0.4 305 20 10 6.3 3.4 42.1 107.8 7.1 M M 24000 -16.1 3.0 310 18 9 6.6 3.6 40.8 105.5 6.1 M M 23000 -14.1 6.6 315 17 9 6.6 3.6 39.7 103.4 5.2 M M 22000 -12.2 10.0 320 15 8 6.6 3.6 38.6 101.6 4.4 M M 21000 -10.2 13.6 315 15 8 6.6 3.6 37.4 99.4 3.4 M M 20000 -8.3 17.1 310 15 8 6.7 3.7 36.4 97.4 2.4 M M 19500 -7.3 18.9 310 15 8 6.7 3.7 35.9 96.6 2.0 M M 19000 -6.3 20.7 305 15 8 7.3 4.0 35.4 95.7 1.6 M M 18500 -4.7 23.5 300 14 7 7.3 4.0 34.8 94.6 0.9 M M 18000 -3.6 25.5 295 13 7 8.0 4.4 34.4 93.9 0.6 M M 17500 -2.5 27.5 290 12 6 8.0 4.4 34.1 93.4 0.2 M M 17000 -1.4 29.5 285 11 6 8.6 4.7 33.8 92.9 -0.1 1081 5.5 16500 -0.1 31.8 275 11 5 8.9 4.9 33.7 92.6 -0.3 1028 5.2 16000 1.2 34.2 270 10 5 9.0 4.9 33.6 92.4 -0.4 975 5.0 15500 2.5 36.5 265 9 5 9.1 5.0 33.4 92.2 -0.6 921 4.7 15000 3.8 38.8 260 9 4 9.1 5.0 33.3 92.0 -0.8 867 4.4 14500 5.1 41.2 255 8 4 9.0 4.9 33.2 91.8 -0.9 813 4.1 14000 6.5 43.7 250 8 4 9.0 4.9 33.1 91.5 -1.0 758 3.9 13500 7.8 46.0 250 7 4 8.8 4.8 32.9 91.3 -1.2 704 3.6 13000 9.1 48.4 250 7 3 8.7 4.8 32.8 91.0 -1.3 650 3.3 12500 10.4 50.7 250 6 3 8.6 4.7 32.6 90.7 -1.5 596 3.0 12000 11.6 52.9 250 6 3 8.5 4.7 32.4 90.3 -1.7 544 2.8 11500 12.9 55.2 255 5 3 8.4 4.6 32.2 90.0 -1.9 491 2.5 11000 14.1 57.4 255 5 2 7.9 4.3 32.0 89.5 -2.1 440 2.2 10500 15.3 59.5 260 4 2 3.9 2.1 31.7 89.1 -2.4 389 2.0 10250 15.4 59.7 250 4 2 4.6 2.5 31.1 88.0 -3.0 378 1.9 10000 16.1 61.0 260 4 2 10.4 5.7 31.0 87.9 -3.1 350 1.8 9750 16.8 62.2 270 3 2 9.4 5.1 31.0 87.8 -3.1 323 1.6 9500 17.5 63.5 285 2 1 7.6 4.2 31.0 87.8 -3.2 295 1.5 9250 17.9 64.2 295 2 1 4.9 2.7 30.7 87.2 -3.5 275 1.4 9000 18.3 64.9 305 2 1 5.6 3.0 30.3 86.6 -3.9 256 1.3 8750 18.7 65.7 330 3 1 6.3 3.5 30.0 86.0 -4.2 236 1.2 8500 19.1 66.4 350 3 2 4.6 2.5 29.7 85.5 -4.5 216 1.1 8250 19.3 66.7 360 4 2 2.9 1.6 29.2 84.6 -5.0 202 1.0 8000 19.5 67.1 010 5 2 3.1 1.7 28.7 83.7 -5.6 189 1.0 7750 19.7 67.5 015 5 3 2.9 1.6 28.2 82.7 -6.1 176 0.9 7500 19.9 67.8 015 6 3 2.5 1.4 27.7 81.8 -6.7 163 0.8 7250 20.1 68.2 015 6 3 2.2 1.2 27.1 80.7 -7.3 151 0.8 7000 20.2 68.4 020 6 3 2.4 1.3 26.5 79.7 -7.8 139 0.7 6750 20.4 68.7 015 6 3 1.7 0.9 25.9 78.7 -8.4 127 0.6 6500 20.4 68.7 010 6 3 0.4 0.2 25.3 77.5 -9.1 118 0.6 6250 20.4 68.7 005 7 3 -0.4 -0.2 24.5 76.2 -9.9 111 0.6 6000 20.4 68.7 360 7 4 1.3 0.7 23.8 74.8 -10.7 103 0.5 5750 20.4 68.7 360 7 4 -4.3 -2.3 23.1 73.6 -11.4 97 0.5 5500 19.5 67.1 350 5 3 -18.1 -9.9 21.5 70.7 -13.0 115 0.6 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 06/26/2024 at 0900 MDT | 06/26/2024 at 1200 MDT | CAPE... +88.0 LI... -0.3 | CAPE... +296.4 LI... -1.5 CINH... -132.3 K Index... +16.8 | CINH... -105.3 K Index... +16.6 | 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 -84.8 270 29 15 2.5 1.4 | -64.7 -84.5 270 28 15 2.5 1.4 45000 -58.1 -72.6 275 45 23 7.1 3.9 | -58.2 -72.8 275 43 22 6.6 3.6 40000 -47.6 -53.7 280 51 26 6.5 3.6 | -48.3 -54.9 280 51 26 6.8 3.7 38000 -43.7 -46.7 285 53 28 6.5 3.6 | -44.2 -47.6 280 53 27 6.8 3.7 36000 -39.7 -39.5 285 56 29 6.4 3.5 | -40.2 -40.4 280 54 28 6.7 3.7 34000 -35.9 -32.6 285 48 25 6.3 3.5 | -36.2 -33.2 280 46 24 6.6 3.6 32000 -31.7 -25.1 285 40 20 7.1 3.9 | -31.8 -25.2 275 37 19 7.6 4.2 30000 -27.5 -17.5 285 35 18 7.0 3.8 | -27.5 -17.5 275 33 17 7.3 4.0 29000 -25.4 -13.7 290 33 17 7.0 3.8 | -25.3 -13.5 275 32 16 7.3 4.0 28000 -23.4 -10.1 290 30 15 6.6 3.6 | -23.2 -9.8 275 30 15 6.8 3.7 27000 -21.4 -6.5 290 27 14 6.6 3.6 | -21.2 -6.2 280 27 14 6.8 3.7 26000 -19.4 -2.9 290 24 12 6.6 3.6 | -19.1 -2.4 280 25 13 6.8 3.7 25000 -17.4 0.7 290 21 11 6.4 3.5 | -17.1 1.2 280 23 12 6.5 3.6 24000 -15.6 3.9 290 19 10 6.2 3.4 | -15.2 4.6 280 21 11 6.4 3.5 23000 -13.8 7.2 295 17 9 6.2 3.4 | -13.3 8.1 275 19 10 6.4 3.5 22000 -11.9 10.6 295 15 7 6.6 3.6 | -11.4 11.5 275 18 9 6.5 3.6 21000 -9.9 14.2 300 14 7 6.9 3.8 | -9.5 14.9 275 17 9 6.6 3.6 20000 -7.8 18.0 300 14 7 6.9 3.8 | -7.6 18.3 280 16 8 6.6 3.6 19500 -6.8 19.8 300 14 7 7.0 3.8 | -6.6 20.1 280 16 8 6.8 3.7 19000 -5.2 22.6 305 14 7 7.3 4.0 | -5.5 22.1 280 16 8 7.7 4.2 18500 -4.2 24.4 305 13 7 7.3 4.0 | -4.4 24.1 280 15 8 7.6 4.2 18000 -3.1 26.4 305 13 7 7.8 4.3 | -3.3 26.1 280 15 8 8.0 4.4 17500 -1.9 28.6 310 12 6 7.8 4.3 | -1.5 29.3 280 13 7 8.1 4.4 17000 -0.8 30.6 305 11 6 8.3 4.6 | -0.3 31.5 285 12 6 8.4 4.6 16500 0.5 32.9 300 11 5 8.6 4.7 | 1.0 33.8 280 11 6 8.5 4.7 16000 1.7 35.1 295 10 5 8.6 4.7 | 2.3 36.1 275 11 6 8.6 4.7 15500 3.0 37.4 285 9 5 8.6 4.7 | 3.5 38.3 270 10 5 8.7 4.8 15000 4.2 39.6 275 9 5 8.7 4.8 | 4.8 40.6 265 10 5 8.7 4.8 14500 5.4 41.7 265 8 4 8.5 4.7 | 6.0 42.8 255 10 5 8.6 4.7 14000 6.6 43.9 255 8 4 8.6 4.7 | 7.3 45.1 245 10 5 8.7 4.8 13500 7.8 46.0 245 7 4 8.4 4.6 | 8.5 47.3 235 11 6 8.5 4.6 13000 9.1 48.4 240 6 3 8.4 4.6 | 9.7 49.5 230 11 6 8.4 4.6 12500 10.3 50.5 230 6 3 8.1 4.4 | 10.9 51.6 225 11 6 8.0 4.4 12000 11.4 52.5 220 5 3 7.9 4.3 | 12.1 53.8 220 11 5 7.7 4.2 11500 12.6 54.7 210 5 3 7.5 4.1 | 13.2 55.8 215 10 5 7.1 3.9 11000 13.6 56.5 200 4 2 6.9 3.8 | 14.1 57.4 205 9 5 6.2 3.4 10500 14.7 58.5 185 3 2 4.1 2.2 | 15.0 59.0 195 8 4 3.1 1.7 10250 14.9 58.8 180 3 2 4.0 2.2 | 15.1 59.2 200 8 4 2.8 1.5 10000 15.4 59.7 175 3 1 7.8 4.3 | 15.5 59.9 190 7 4 6.6 3.6 9750 15.9 60.6 160 2 1 7.4 4.0 | 15.9 60.6 180 6 3 6.1 3.4 9500 16.4 61.5 140 2 1 5.5 3.0 | 16.3 61.3 165 6 3 4.4 2.4 9250 16.7 62.1 110 1 1 2.9 1.6 | 16.5 61.7 160 5 3 3.2 1.8 9000 16.9 62.4 080 1 1 3.6 2.0 | 16.8 62.2 150 5 3 6.6 3.6 8750 17.1 62.8 055 2 1 4.2 2.3 | 17.4 63.3 145 5 2 8.2 4.5 8500 17.4 63.3 035 2 1 2.9 1.6 | 17.9 64.2 135 5 2 6.4 3.5 8250 17.5 63.5 020 2 1 1.9 1.0 | 18.2 64.8 125 4 2 4.1 2.3 8000 17.7 63.9 010 3 1 1.4 0.8 | 18.5 65.3 110 4 2 7.5 4.1 7750 17.6 63.7 360 4 2 -0.0 -0.0 | 19.2 66.6 100 4 2 10.6 5.8 7500 17.6 63.7 355 5 3 0.3 0.1 | 19.8 67.6 095 4 2 8.7 4.8 7250 17.6 63.7 350 6 3 0.6 0.3 | 20.4 68.7 095 4 2 7.1 3.9 7000 17.5 63.5 350 6 3 0.4 0.2 | 21.0 69.8 090 4 2 9.8 5.4 6750 17.5 63.5 350 7 4 4.0 2.2 | 21.8 71.2 090 4 2 13.2 7.3 6500 17.9 64.2 350 7 4 7.9 4.3 | 22.8 73.0 085 4 2 11.3 6.2 6250 18.5 65.3 350 7 4 8.9 4.9 | 23.5 74.3 085 4 2 9.7 5.3 6000 19.1 66.4 355 7 4 5.9 3.3 | 24.3 75.7 080 4 2 10.3 5.7 5750 19.5 67.1 355 7 4 11.4 6.2 | 25.2 77.4 080 4 2 18.3 10.0 5500 21.0 69.8 355 7 3 28.7 15.8 | 27.1 80.8 080 4 2 31.0 17.0 06/26/2024 at 1500 MDT | 06/26/2024 at 1800 MDT | CAPE... +347.7 LI... -2.1 | CAPE... +140.1 LI... -1.2 CINH... -22.9 K Index... +27.3 | CINH... -70.9 K Index... +31.5 | 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 -65.2 -85.4 270 30 15 2.5 1.4 | -65.6 -86.1 275 30 15 3.0 1.7 45000 -58.5 -73.3 280 42 21 7.0 3.8 | -58.5 -73.3 275 37 19 6.7 3.7 40000 -48.2 -54.8 280 51 26 6.5 3.6 | -48.4 -55.1 275 43 22 7.2 3.9 38000 -44.3 -47.7 280 53 27 6.5 3.6 | -44.1 -47.4 275 40 21 7.2 3.9 36000 -40.4 -40.7 275 55 28 7.1 3.9 | -39.7 -39.5 270 37 19 7.6 4.2 34000 -35.9 -32.6 275 50 26 7.5 4.1 | -35.0 -31.0 265 35 18 7.8 4.3 32000 -30.9 -23.6 270 45 23 8.1 4.4 | -29.8 -21.6 255 32 17 8.4 4.6 30000 -26.6 -15.9 270 37 19 7.4 4.0 | -25.5 -13.9 260 28 14 7.3 4.0 29000 -24.4 -11.9 270 33 17 7.4 4.0 | -23.3 -9.9 260 25 13 7.3 4.0 28000 -22.3 -8.1 270 30 15 6.6 3.6 | -21.2 -6.2 260 23 12 7.0 3.8 27000 -20.3 -4.5 270 29 15 6.6 3.6 | -19.1 -2.4 255 19 10 7.1 3.9 26000 -18.4 -1.1 270 28 14 6.7 3.7 | -17.1 1.2 255 15 8 7.1 3.9 25000 -16.4 2.5 270 27 14 6.1 3.3 | -15.0 5.0 245 12 6 6.8 3.7 24000 -14.7 5.5 265 25 13 5.8 3.2 | -13.1 8.4 235 13 7 6.6 3.6 23000 -13.1 8.4 265 24 12 5.8 3.2 | -11.1 12.0 230 14 7 6.7 3.6 22000 -11.4 11.5 260 22 11 6.4 3.5 | -9.2 15.4 220 15 8 6.1 3.3 21000 -9.4 15.1 255 21 11 6.7 3.7 | -7.6 18.3 220 16 8 5.6 3.1 20000 -7.5 18.5 250 20 10 6.7 3.7 | -6.0 21.2 215 18 9 5.7 3.1 19500 -6.5 20.3 245 19 10 6.8 3.7 | -5.2 22.6 215 19 10 5.7 3.1 19000 -5.4 22.3 245 18 9 7.4 4.1 | -4.0 24.8 210 20 10 5.4 2.9 18500 -4.4 24.1 240 17 9 7.4 4.1 | -3.2 26.2 210 20 10 5.3 2.9 18000 -3.3 26.1 235 16 8 8.0 4.4 | -2.4 27.7 210 20 10 6.3 3.4 17500 -1.5 29.3 230 14 7 8.3 4.5 | -1.5 29.3 210 20 10 6.2 3.4 17000 -0.2 31.6 230 13 7 8.7 4.8 | -0.7 30.7 210 20 10 6.9 3.8 16500 1.1 34.0 225 12 6 8.8 4.9 | 0.4 32.7 210 19 10 7.5 4.1 16000 2.4 36.3 225 11 6 8.9 4.9 | 1.5 34.7 215 19 10 7.5 4.1 15500 3.7 38.7 220 11 6 9.0 4.9 | 2.7 36.9 215 18 9 8.6 4.7 15000 5.0 41.0 215 11 5 9.0 4.9 | 4.0 39.2 215 17 9 8.5 4.7 14500 6.3 43.3 210 10 5 8.6 4.7 | 5.2 41.4 215 16 8 8.7 4.8 14000 7.6 45.7 205 11 5 8.7 4.8 | 6.5 43.7 220 15 8 8.7 4.8 13500 8.9 48.0 200 11 5 8.4 4.6 | 7.8 46.0 220 15 8 8.7 4.8 13000 10.0 50.0 190 10 5 8.3 4.6 | 9.0 48.2 220 14 7 8.6 4.7 12500 11.2 52.2 185 10 5 8.2 4.5 | 10.3 50.5 225 13 7 8.5 4.7 12000 12.4 54.3 170 10 5 8.1 4.5 | 11.5 52.7 225 12 6 8.4 4.6 11500 13.5 56.3 160 9 5 8.4 4.6 | 12.7 54.9 225 11 6 8.4 4.6 11000 14.8 58.6 150 9 5 8.6 4.7 | 13.9 57.0 230 11 6 8.2 4.5 10500 16.1 61.0 145 9 5 5.2 2.9 | 15.2 59.4 230 10 5 4.4 2.4 10250 16.4 61.5 145 9 5 7.0 3.9 | 15.4 59.7 230 10 5 5.4 3.0 10000 17.2 63.0 145 9 5 12.6 6.9 | 16.1 61.0 230 9 5 11.2 6.1 9750 18.1 64.6 145 9 5 11.9 6.5 | 16.8 62.2 230 9 5 10.1 5.6 9500 18.9 66.0 145 9 5 9.1 5.0 | 17.5 63.5 235 9 5 8.5 4.7 9250 19.5 67.1 145 9 4 7.5 4.1 | 18.0 64.4 230 9 4 6.1 3.4 9000 20.2 68.4 140 8 4 10.7 5.9 | 18.5 65.3 230 8 4 8.2 4.5 8750 21.0 69.8 140 8 4 11.4 6.3 | 19.2 66.6 235 8 4 9.8 5.4 8500 21.8 71.2 140 8 4 9.9 5.4 | 19.9 67.8 235 8 4 8.2 4.5 8250 22.4 72.3 140 8 4 7.9 4.3 | 20.4 68.7 235 8 4 5.3 2.9 8000 23.1 73.6 140 8 4 9.9 5.4 | 20.7 69.3 235 8 4 6.8 3.7 7750 23.9 75.0 140 8 4 12.0 6.6 | 21.4 70.5 235 9 4 9.7 5.3 7500 24.7 76.5 135 7 4 9.7 5.3 | 22.0 71.6 235 9 4 7.2 4.0 7250 25.4 77.7 135 7 4 7.6 4.2 | 22.4 72.3 235 9 5 4.6 2.5 7000 26.0 78.8 135 7 4 9.7 5.3 | 22.7 72.9 235 10 5 6.0 3.3 6750 26.8 80.2 135 7 3 12.7 7.0 | 23.3 73.9 235 11 5 9.9 5.4 6500 27.8 82.0 135 6 3 11.3 6.2 | 24.0 75.2 235 11 6 8.9 4.9 6250 28.5 83.3 135 6 3 10.0 5.5 | 24.5 76.1 235 11 6 6.8 3.7 6000 29.3 84.7 135 6 3 9.3 5.1 | 24.9 76.8 230 11 6 6.8 3.7 5750 30.0 86.0 135 6 3 14.5 8.0 | 25.4 77.7 230 11 6 8.7 4.7 5500 31.6 88.9 130 5 3 28.3 15.6 | 26.2 79.2 230 10 5 15.4 8.5 ________________________________________________________________________________ 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