Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
696 UXUS97 KBOU 190018 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1816 MDT Tuesday, June 18, 2024 This forecast is for Wednesday, June 19, 2024: If the trigger temperature of 63.3 F/17.4 C is reached...then Thermal Soaring Index....................... Fair Maximum rate of lift........................ 394 ft/min (2.0 m/s) Maximum height of thermals.................. 13223 ft MSL (7933 ft AGL) Forecast maximum temperature................... 73.0 F/23.2 C Time of trigger temperature.................... 1045 MDT Time of overdevelopment........................ None Middle/high clouds during soaring window....... Overcast opaque high Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 11045 ft MSL (5754 ft AGL) Thermal soaring outlook for Thursday 06/20..... Good Wave Soaring Index............................. Good Wave Soaring Index trend (to 1800 MDT)......... No change Height of stable layer (12-18K ft MSL)......... 13652 ft MSL (8362 ft AGL) Weak PVA/NVA (through 1800 MDT)................ Neither Potential height of wave....................... 46605 ft MSL (41315 ft AGL) Wave soaring outlook for Thursday 06/20........ Poor Remarks... Sunrise/Sunset.................... 05:31:22 / 20:30:42 MDT Total possible sunshine........... 14 hr 59 min 20 sec (899 min 20 sec) Altitude of sun at 13:01:02 MDT... 73.67 degrees Upper air data from numerical model forecast valid on 06/19/2024 at 0600 MDT Freezing level.................. 12231 ft MSL (6941 ft AGL) Convective condensation level... 12835 ft MSL (7545 ft AGL) Lifted condensation level....... 13249 ft MSL (7959 ft AGL) Lifted index.................... +2.7 K index......................... +17.1 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 -60.4 -76.7 230 70 36 1.9 1.0 M M M M M 45000 -57.2 -71.0 220 75 39 2.5 1.3 M M M M M 40000 -53.3 -63.9 215 67 35 5.8 3.2 M M M M M 38000 -50.0 -58.0 215 64 33 5.4 3.0 M M M M M 36000 -46.8 -52.2 215 61 32 5.4 3.0 M M M M M 34000 -42.7 -44.9 220 59 30 7.5 4.1 M M M M M 32000 -38.2 -36.8 225 56 29 7.5 4.1 M M M M M 30000 -33.1 -27.6 225 55 28 7.6 4.2 43.1 109.6 15.4 M M 29000 -30.8 -23.4 225 55 28 7.6 4.2 42.3 108.1 15.0 M M 28000 -28.5 -19.3 225 54 28 7.6 4.2 41.6 106.9 14.6 M M 27000 -26.2 -15.2 225 53 27 7.6 4.2 40.7 105.3 14.1 M M 26000 -23.9 -11.0 230 52 27 7.6 4.2 39.9 103.8 13.6 M M 25000 -21.6 -6.9 230 51 26 7.7 4.2 39.2 102.5 13.2 M M 24000 -19.4 -2.9 230 50 26 7.1 3.9 38.2 100.8 12.6 M M 23000 -17.3 0.9 230 49 25 7.1 3.9 37.2 99.0 11.9 M M 22000 -15.2 4.6 230 48 25 7.2 3.9 36.4 97.5 11.3 M M 21000 -13.2 8.2 230 47 24 6.6 3.6 35.2 95.4 10.4 M M 20000 -11.3 11.7 230 47 24 6.7 3.6 34.1 93.4 9.5 M M 19500 -10.3 13.5 230 47 24 6.7 3.7 33.6 92.5 9.1 M M 19000 -9.4 15.1 235 47 24 6.7 3.7 33.1 91.6 8.7 M M 18500 -8.4 16.9 235 46 24 6.8 3.7 32.6 90.6 8.2 M M 18000 -7.5 18.5 235 45 23 6.7 3.7 32.1 89.7 7.7 M M 17500 -6.4 20.5 235 44 23 8.1 4.4 31.7 89.0 7.3 M M 17000 -5.3 22.5 235 42 22 8.0 4.4 31.4 88.5 7.1 M M 16500 -4.2 24.4 235 41 21 7.5 4.1 31.1 87.9 6.8 M M 16000 -3.1 26.4 235 38 19 7.0 3.9 30.6 87.1 6.4 M M 15500 -2.0 28.4 230 35 18 6.1 3.4 30.2 86.3 6.1 M M 15000 -1.6 29.1 230 29 15 1.5 0.8 28.3 83.0 4.4 M M 14500 -1.4 29.5 225 25 13 1.3 0.7 27.0 80.6 3.1 M M 14000 -1.3 29.7 215 22 11 1.2 0.7 25.5 78.0 1.8 M M 13500 -1.2 29.8 205 19 10 1.8 1.0 24.1 75.5 0.4 M M 13000 -0.8 30.6 195 17 9 3.6 2.0 23.0 73.5 -0.6 576 2.9 12500 -0.3 31.5 185 17 9 3.9 2.2 22.0 71.7 -1.6 547 2.8 12000 0.6 33.1 175 16 8 7.2 3.9 21.4 70.5 -2.2 505 2.6 11500 1.7 35.1 170 16 8 6.9 3.8 21.0 69.8 -2.6 459 2.3 11000 2.6 36.7 165 15 8 6.0 3.3 20.4 68.8 -3.1 416 2.1 10500 3.5 38.3 160 15 8 5.4 3.0 19.9 67.7 -3.7 374 1.9 10250 3.8 38.8 160 14 7 3.5 1.9 19.4 67.0 -4.1 357 1.8 10000 4.1 39.4 160 14 7 5.9 3.2 19.0 66.2 -4.6 341 1.7 9750 4.7 40.5 155 14 7 8.5 4.7 18.8 65.9 -4.7 317 1.6 9500 5.2 41.4 155 13 7 6.8 3.7 18.7 65.6 -4.9 293 1.5 9250 5.6 42.1 150 14 7 4.1 2.2 18.4 65.0 -5.3 274 1.4 9000 5.9 42.6 145 14 7 5.6 3.1 17.9 64.2 -5.7 257 1.3 8750 6.5 43.7 145 15 8 8.7 4.8 17.8 64.0 -5.9 234 1.2 8500 7.1 44.8 140 16 8 8.1 4.4 17.7 63.8 -6.1 208 1.1 8250 7.6 45.7 140 16 8 7.2 4.0 17.5 63.5 -6.2 184 0.9 8000 8.2 46.8 140 15 8 8.1 4.5 17.3 63.2 -6.4 160 0.8 7750 8.9 48.0 140 15 8 10.6 5.8 17.3 63.1 -6.5 132 0.7 7500 9.7 49.5 140 15 7 9.4 5.2 17.4 63.2 -6.4 101 0.5 7250 10.3 50.5 135 14 7 7.4 4.1 17.2 63.0 -6.6 75 0.4 7000 10.9 51.6 135 14 7 8.6 4.7 17.1 62.7 -6.7 50 0.3 6750 11.6 52.9 135 13 7 10.4 5.7 17.1 62.7 -6.7 20 0.1 6500 12.4 54.3 130 12 6 9.4 5.2 17.1 62.8 -6.6 M M 6250 13.1 55.6 130 11 6 8.6 4.7 17.0 62.6 -6.7 M M 6000 13.7 56.7 125 11 5 6.8 3.8 16.9 62.4 -6.8 M M 5750 14.1 57.4 125 9 5 5.8 3.2 16.6 61.9 -7.1 M M 5500 14.7 58.5 120 7 4 10.7 5.9 16.5 61.6 -7.3 M M * * * * * * Numerical weather prediction model forecast data valid * * * * * * 06/19/2024 at 0900 MDT | 06/19/2024 at 1200 MDT | CAPE... +6.5 LI... +1.1 | CAPE... +29.0 LI... -0.4 CINH... -0.2 K Index... +21.1 | CINH... -55.1 K Index... +22.2 | 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 -59.5 -75.1 225 68 35 2.0 1.1 | -58.8 -73.8 225 67 35 1.7 0.9 45000 -56.6 -69.9 220 84 43 1.5 0.8 | -56.3 -69.3 220 82 42 1.5 0.8 40000 -54.0 -65.2 220 73 38 6.0 3.3 | -53.8 -64.8 225 71 36 5.4 2.9 38000 -50.6 -59.1 215 67 35 5.7 3.1 | -50.7 -59.3 225 66 34 5.1 2.8 36000 -47.2 -53.0 215 62 32 5.7 3.1 | -47.6 -53.7 225 61 32 5.2 2.8 34000 -43.0 -45.4 220 57 29 7.4 4.1 | -42.7 -44.9 225 56 29 7.9 4.4 32000 -38.0 -36.4 220 52 27 7.4 4.1 | -38.0 -36.4 225 52 27 7.9 4.3 30000 -33.3 -27.9 220 50 26 8.0 4.4 | -33.2 -27.8 220 49 25 8.1 4.4 29000 -30.9 -23.6 220 49 25 8.0 4.4 | -30.7 -23.3 220 47 24 8.1 4.4 28000 -28.5 -19.3 220 48 25 7.8 4.3 | -28.3 -18.9 220 46 24 7.7 4.2 27000 -26.3 -15.3 220 47 24 7.2 4.0 | -26.2 -15.2 220 46 23 7.0 3.8 26000 -24.2 -11.6 220 46 24 7.2 4.0 | -24.1 -11.4 220 45 23 7.1 3.9 25000 -22.0 -7.6 220 45 23 7.2 4.0 | -22.1 -7.8 220 45 23 7.1 3.9 24000 -19.8 -3.6 225 45 23 7.4 4.0 | -19.8 -3.6 220 44 22 7.7 4.2 23000 -17.6 0.3 225 45 23 7.4 4.1 | -17.5 0.5 225 42 22 7.8 4.3 22000 -15.4 4.3 230 45 23 7.5 4.1 | -15.2 4.6 225 41 21 7.8 4.3 21000 -13.4 7.9 230 45 23 7.1 3.9 | -13.1 8.4 225 42 21 6.9 3.8 20000 -11.3 11.7 230 46 24 7.2 3.9 | -11.1 12.0 225 42 22 7.0 3.8 19500 -10.3 13.5 225 47 24 7.3 4.0 | -10.1 13.8 225 42 22 7.0 3.8 19000 -9.3 15.3 225 47 24 7.3 4.0 | -9.0 15.8 225 42 22 8.0 4.4 18500 -8.2 17.2 225 46 24 7.3 4.0 | -7.8 18.0 225 42 22 8.3 4.6 18000 -7.2 19.0 225 45 23 7.3 4.0 | -6.6 20.1 220 41 21 8.3 4.6 17500 -6.1 21.0 225 43 22 7.8 4.3 | -5.4 22.3 220 40 21 8.0 4.4 17000 -4.9 23.2 225 41 21 7.8 4.3 | -4.2 24.4 220 39 20 8.1 4.4 16500 -3.3 26.1 225 37 19 6.4 3.5 | -2.4 27.7 215 36 19 7.7 4.2 16000 -2.4 27.7 225 34 18 6.6 3.6 | -1.3 29.7 215 34 18 7.8 4.3 15500 -1.5 29.3 220 32 16 5.2 2.9 | -0.2 31.6 215 33 17 6.6 3.6 15000 -0.8 30.6 215 30 16 5.1 2.8 | 0.7 33.3 215 31 16 6.6 3.6 14500 -0.1 31.8 210 29 15 4.4 2.4 | 1.6 34.9 210 29 15 5.2 2.9 14000 0.4 32.7 205 27 14 3.9 2.2 | 2.2 36.0 210 27 14 4.4 2.4 13500 0.9 33.6 195 26 14 4.0 2.2 | 2.8 37.0 210 25 13 3.5 1.9 13000 1.5 34.7 190 25 13 4.3 2.3 | 3.0 37.4 205 23 12 1.9 1.1 12500 2.0 35.6 185 23 12 4.3 2.4 | 3.2 37.8 200 20 10 2.5 1.4 12000 2.7 36.9 185 21 11 4.5 2.4 | 3.7 38.7 195 19 10 4.5 2.5 11500 3.3 37.9 180 18 9 4.2 2.3 | 4.3 39.7 190 18 9 4.4 2.4 11000 3.8 38.8 175 16 8 2.6 1.4 | 4.8 40.6 185 18 9 4.0 2.2 10500 4.2 39.6 170 14 7 2.2 1.2 | 5.4 41.7 180 17 9 3.5 1.9 10250 4.3 39.7 170 13 7 0.8 0.4 | 5.6 42.1 180 17 9 1.9 1.0 10000 4.4 39.9 170 13 7 3.5 1.9 | 5.7 42.3 180 17 9 2.8 1.5 9750 4.8 40.6 165 14 7 6.0 3.3 | 6.0 42.8 175 17 9 4.0 2.2 9500 5.2 41.4 160 14 7 4.9 2.7 | 6.3 43.3 175 17 9 3.4 1.8 9250 5.5 41.9 160 14 7 3.6 2.0 | 6.5 43.7 170 17 9 2.1 1.1 9000 5.8 42.4 155 14 7 5.2 2.9 | 6.7 44.1 170 17 9 3.7 2.0 8750 6.3 43.3 150 15 8 8.4 4.6 | 7.1 44.8 165 17 9 6.7 3.7 8500 6.9 44.4 145 15 8 7.1 3.9 | 7.5 45.5 160 17 9 5.6 3.1 8250 7.3 45.1 145 15 8 5.4 3.0 | 7.9 46.2 155 17 9 4.2 2.3 8000 7.7 45.9 145 15 8 6.5 3.6 | 8.2 46.8 155 16 8 5.6 3.1 7750 8.3 46.9 140 15 8 8.7 4.8 | 8.7 47.7 150 16 8 9.0 4.9 7500 8.9 48.0 140 14 7 8.1 4.5 | 9.4 48.9 145 15 8 7.9 4.3 7250 9.4 48.9 140 13 7 6.4 3.5 | 9.8 49.6 145 15 8 5.3 2.9 7000 9.9 49.8 140 13 7 7.6 4.2 | 10.3 50.5 140 15 8 6.9 3.8 6750 10.6 51.1 140 12 6 10.8 5.9 | 10.9 51.6 140 15 8 10.9 6.0 6500 11.5 52.7 135 11 6 11.0 6.0 | 11.7 53.1 135 14 7 10.9 6.0 6250 12.2 54.0 135 11 5 10.0 5.5 | 12.4 54.3 135 13 7 9.6 5.2 6000 12.9 55.2 135 10 5 8.5 4.7 | 13.1 55.6 135 13 7 8.0 4.4 5750 13.5 56.3 135 10 5 10.5 5.7 | 13.7 56.7 135 13 7 10.9 6.0 5500 14.7 58.5 135 9 5 19.7 10.8 | 14.9 58.8 130 11 6 22.1 12.1 06/19/2024 at 1500 MDT | 06/19/2024 at 1800 MDT | CAPE... +170.2 LI... -0.4 | CAPE... +99.1 LI... -1.0 CINH... -126.4 K Index... +25.1 | CINH... -111.7 K Index... +28.0 | 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 -59.4 -74.9 225 68 35 1.5 0.8 | -60.3 -76.5 225 71 36 1.7 0.9 45000 -56.9 -70.4 225 81 42 2.2 1.2 | -57.4 -71.3 225 80 41 2.2 1.2 40000 -52.9 -63.2 240 49 25 6.3 3.4 | -53.3 -63.9 230 50 26 6.8 3.8 38000 -49.2 -56.6 245 45 23 6.3 3.5 | -49.1 -56.4 230 45 23 7.0 3.8 36000 -45.4 -49.7 245 40 21 6.3 3.5 | -44.9 -48.8 235 40 21 7.0 3.8 34000 -41.6 -42.9 240 42 22 6.3 3.5 | -40.3 -40.5 235 38 20 7.7 4.2 32000 -37.8 -36.0 230 47 24 6.4 3.5 | -35.7 -32.3 240 37 19 7.8 4.3 30000 -33.1 -27.6 225 47 24 8.2 4.5 | -31.3 -24.3 235 36 18 7.4 4.0 29000 -30.7 -23.3 225 46 24 8.2 4.5 | -28.5 -19.3 235 35 18 7.4 4.0 28000 -28.2 -18.8 225 45 23 8.2 4.5 | -26.3 -15.3 235 35 18 7.5 4.1 27000 -25.8 -14.4 225 43 22 7.9 4.4 | -24.1 -11.4 235 35 18 7.5 4.1 26000 -22.9 -9.2 225 42 21 7.9 4.4 | -21.9 -7.4 235 35 18 7.5 4.1 25000 -20.5 -4.9 225 40 21 7.9 4.3 | -19.7 -3.5 235 35 18 7.5 4.1 24000 -18.3 -0.9 225 40 21 7.3 4.0 | -17.6 0.3 235 37 19 6.9 3.8 23000 -16.2 2.8 230 41 21 7.3 4.0 | -15.6 3.9 230 39 20 6.9 3.8 22000 -14.0 6.8 230 41 21 7.4 4.1 | -13.6 7.5 230 41 21 6.9 3.8 21000 -11.8 10.8 235 40 21 7.6 4.2 | -11.6 11.1 230 40 20 7.0 3.8 20000 -9.6 14.7 235 39 20 7.7 4.2 | -9.6 14.7 235 38 20 7.0 3.8 19500 -8.5 16.7 235 38 20 7.8 4.3 | -8.5 16.7 235 37 19 7.0 3.8 19000 -7.4 18.7 235 37 19 6.8 3.7 | -7.5 18.5 235 37 19 6.7 3.7 18500 -6.5 20.3 235 36 18 6.8 3.7 | -6.6 20.1 235 35 18 6.7 3.7 18000 -5.5 22.1 235 34 18 7.0 3.8 | -5.6 21.9 235 34 18 6.7 3.7 17500 -4.4 24.1 235 33 17 7.2 4.0 | -4.6 23.7 235 33 17 6.7 3.7 17000 -3.4 25.9 235 32 17 7.2 4.0 | -3.7 25.3 235 31 16 6.6 3.6 16500 -2.3 27.9 235 31 16 7.5 4.1 | -2.6 27.3 235 30 16 7.7 4.2 16000 -1.2 29.8 235 30 16 7.5 4.1 | -1.5 29.3 235 30 16 7.7 4.2 15500 -0.2 31.6 230 29 15 7.1 3.9 | -0.4 31.3 230 31 16 7.5 4.1 15000 0.8 33.4 230 29 15 6.8 3.8 | 0.6 33.1 230 31 16 7.2 4.0 14500 1.8 35.2 225 28 14 6.7 3.7 | 1.7 35.1 230 30 16 7.2 4.0 14000 2.7 36.9 225 27 14 6.2 3.4 | 2.7 36.9 225 29 15 6.9 3.8 13500 3.6 38.5 220 25 13 6.2 3.4 | 4.2 39.6 225 26 13 7.2 3.9 13000 4.4 39.9 215 24 12 5.3 2.9 | 5.3 41.5 220 24 12 7.4 4.1 12500 5.1 41.2 215 22 11 5.5 3.0 | 6.4 43.5 220 22 11 6.8 3.7 12000 5.8 42.4 205 21 11 4.1 2.2 | 7.1 44.8 215 19 10 5.1 2.8 11500 6.3 43.3 200 20 10 4.1 2.3 | 7.8 46.0 210 17 9 4.5 2.5 11000 6.9 44.4 190 19 10 5.6 3.1 | 8.2 46.8 205 14 7 1.9 1.1 10500 7.7 45.9 185 19 10 6.2 3.4 | 8.4 47.1 200 12 6 1.1 0.6 10250 8.2 46.8 185 19 10 2.6 1.4 | 8.4 47.1 200 11 6 1.2 0.6 10000 8.6 47.5 185 18 9 7.6 4.2 | 8.6 47.5 200 10 5 4.0 2.2 9750 9.2 48.6 180 18 9 9.9 5.4 | 8.9 48.0 195 9 5 4.8 2.6 9500 9.9 49.8 180 17 9 5.5 3.0 | 9.2 48.6 190 9 4 4.3 2.4 9250 10.0 50.0 175 17 9 -0.4 -0.2 | 9.5 49.1 190 8 4 3.0 1.6 9000 10.1 50.2 175 16 8 4.0 2.2 | 9.7 49.5 185 8 4 5.5 3.0 8750 10.5 50.9 170 16 8 7.8 4.3 | 10.2 50.4 180 7 3 8.4 4.6 8500 11.0 51.8 165 16 8 5.0 2.7 | 10.8 51.4 170 6 3 6.8 3.7 8250 11.2 52.2 160 16 8 2.6 1.4 | 11.2 52.2 165 6 3 5.3 2.9 8000 11.5 52.7 155 16 8 6.1 3.3 | 11.6 52.9 155 5 3 6.8 3.8 7750 12.1 53.8 150 16 8 10.8 5.9 | 12.2 54.0 145 5 2 9.7 5.3 7500 12.9 55.2 140 16 8 9.4 5.1 | 13.1 55.6 135 4 2 8.7 4.8 7250 13.5 56.3 140 16 8 6.6 3.6 | 13.5 56.3 130 4 2 6.9 3.8 7000 14.1 57.4 140 17 8 10.4 5.7 | 14.1 57.4 120 4 2 8.2 4.5 6750 15.0 59.0 140 17 9 14.0 7.7 | 14.8 58.6 110 3 2 11.4 6.2 6500 16.0 60.8 135 17 9 11.3 6.2 | 15.6 60.1 105 3 2 10.9 6.0 6250 16.8 62.2 135 17 9 11.8 6.5 | 16.4 61.5 095 3 1 10.2 5.6 6000 17.6 63.7 135 16 8 6.2 3.4 | 17.1 62.8 090 3 1 6.9 3.8 5750 18.0 64.4 135 16 8 11.1 6.1 | 17.5 63.5 090 3 1 8.8 4.8 5500 19.7 67.5 130 15 8 36.4 20.0 | 18.7 65.7 090 3 1 23.5 12.9 ________________________________________________________________________________ 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