Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
483 UXUS97 KBOU 011344 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0730 MDT Monday, July 1, 2024 This forecast is for Monday, July 1, 2024: If the trigger temperature of 85.5 F/29.7 C is reached...then Thermal Soaring Index....................... Good Maximum rate of lift........................ 700 ft/min (3.6 m/s) Maximum height of thermals.................. 15158 ft MSL (9825 ft AGL) Forecast maximum temperature................... 90.0 F/32.7 C Time of trigger temperature.................... 1045 MDT Time of overdevelopment........................ None 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................. 8273 ft MSL (2940 ft AGL) Thermal soaring outlook for Tuesday 07/02...... Fair 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....................... 41202 ft MSL (35869 ft AGL) Wave soaring outlook for Tuesday 07/02......... Poor Remarks... Sunrise/Sunset.................... 05:35:36 / 20:31:27 MDT Total possible sunshine........... 14 hr 55 min 51 sec (895 min 51 sec) Altitude of sun at 13:03:32 MDT... 73.24 degrees Upper air data from numerical model forecast valid on 07/01/2024 at 0600 MDT Freezing level.................. 16338 ft MSL (11005 ft AGL) Convective condensation level... 15526 ft MSL (10193 ft AGL) Lifted condensation level....... 15511 ft MSL (10178 ft AGL) Lifted index.................... -1.5 K index......................... +28.3 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 -64.2 -83.6 240 31 16 2.0 1.1 M M M M M 45000 -58.4 -73.1 235 45 23 6.2 3.4 M M M M M 40000 -48.7 -55.7 235 52 27 7.6 4.2 M M M M M 38000 -44.2 -47.6 235 52 27 7.6 4.2 M M M M M 36000 -39.6 -39.3 230 52 27 7.5 4.1 M M M M M 34000 -35.2 -31.4 230 48 25 7.5 4.1 M M M M M 32000 -30.7 -23.3 230 45 23 8.5 4.6 M M M M M 30000 -25.8 -14.4 230 44 22 7.3 4.0 50.3 122.6 13.7 M M 29000 -23.7 -10.7 230 43 22 7.3 4.0 49.4 121.0 13.1 M M 28000 -21.6 -6.9 230 43 22 6.1 3.4 48.5 119.2 12.5 M M 27000 -19.7 -3.5 230 41 21 6.3 3.4 47.0 116.6 11.5 M M 26000 -17.9 -0.2 230 40 21 6.3 3.5 45.7 114.3 10.5 M M 25000 -16.1 3.0 230 39 20 6.2 3.4 44.6 112.2 9.7 M M 24000 -14.3 6.3 225 37 19 6.2 3.4 43.1 109.7 8.6 M M 23000 -12.5 9.5 225 34 18 6.2 3.4 41.8 107.3 7.5 M M 22000 -10.7 12.7 225 32 16 6.1 3.3 40.7 105.2 6.6 M M 21000 -9.0 15.8 225 29 15 6.0 3.3 39.2 102.6 5.4 M M 20000 -7.2 19.0 225 26 13 6.0 3.3 37.9 100.3 4.2 M M 19500 -6.4 20.5 225 24 12 6.0 3.3 37.3 99.2 3.7 M M 19000 -5.5 22.1 225 22 12 6.4 3.5 36.7 98.1 3.2 M M 18500 -4.6 23.7 230 21 11 6.4 3.5 36.1 97.1 2.7 M M 18000 -3.6 25.5 230 19 10 6.5 3.5 35.6 96.1 2.1 M M 17500 -2.7 27.1 230 18 9 6.5 3.6 35.0 95.0 1.6 M M 17000 -1.3 29.7 230 16 8 7.1 3.9 34.2 93.6 0.9 M M 16500 -0.1 31.8 230 15 8 7.8 4.3 33.9 93.0 0.6 M M 16000 1.0 33.8 230 14 7 7.8 4.3 33.6 92.4 0.3 M M 15500 2.3 36.1 230 13 7 9.0 5.0 33.4 92.1 0.1 M M 15000 3.6 38.5 225 13 6 9.0 4.9 33.2 91.8 -0.1 874 4.4 14500 4.9 40.8 225 12 6 8.6 4.7 33.1 91.6 -0.2 820 4.2 14000 6.2 43.2 225 11 6 8.6 4.7 32.9 91.2 -0.4 767 3.9 13500 7.4 45.3 230 11 6 8.6 4.7 32.7 90.9 -0.6 714 3.6 13000 8.7 47.7 235 11 6 8.7 4.8 32.5 90.5 -0.8 661 3.4 12500 10.0 50.0 240 11 6 8.7 4.7 32.4 90.2 -1.0 608 3.1 12000 11.3 52.3 245 12 6 8.6 4.7 32.2 89.9 -1.2 556 2.8 11500 12.5 54.5 245 12 6 8.6 4.7 32.0 89.6 -1.3 503 2.6 11000 13.8 56.8 250 13 7 8.2 4.5 31.8 89.2 -1.6 451 2.3 10500 15.0 59.0 255 14 7 4.7 2.6 31.6 88.9 -1.8 399 2.0 10250 15.2 59.4 255 14 7 5.7 3.1 31.1 87.9 -2.3 385 2.0 10000 15.9 60.6 255 14 7 11.1 6.1 31.1 87.9 -2.3 356 1.8 9750 16.7 62.1 260 15 8 10.0 5.5 31.1 88.0 -2.3 327 1.7 9500 17.4 63.3 260 15 8 9.1 5.0 31.1 88.0 -2.3 298 1.5 9250 18.0 64.4 260 15 8 7.0 3.8 31.0 87.8 -2.5 273 1.4 9000 18.5 65.3 260 15 8 8.2 4.5 30.8 87.4 -2.7 250 1.3 8750 19.2 66.6 260 15 8 9.5 5.2 30.7 87.3 -2.7 223 1.1 8500 19.8 67.6 260 15 8 8.5 4.7 30.7 87.2 -2.8 195 1.0 8250 20.4 68.7 265 15 7 6.7 3.7 30.5 87.0 -3.0 171 0.9 8000 20.8 69.4 265 14 7 7.0 3.8 30.3 86.5 -3.3 150 0.8 7750 21.4 70.5 265 13 7 8.4 4.6 30.1 86.2 -3.4 125 0.6 7500 22.0 71.6 260 13 7 7.1 3.9 30.0 86.0 -3.6 100 0.5 7250 22.4 72.3 265 12 6 5.7 3.1 29.7 85.5 -3.9 80 0.4 7000 22.9 73.2 265 11 6 5.4 3.0 29.4 84.9 -4.2 60 0.3 6750 23.2 73.8 260 11 6 5.9 3.2 29.1 84.4 -4.5 41 0.2 6500 23.6 74.5 255 11 6 2.1 1.1 28.7 83.7 -5.0 24 0.1 6250 23.4 74.1 245 10 5 -1.5 -0.8 27.9 82.3 -5.8 20 0.1 6000 23.3 73.9 235 9 5 -0.0 -0.0 27.1 80.9 -6.7 16 0.1 5750 23.1 73.6 225 9 5 -4.6 -2.5 26.3 79.4 -7.6 14 0.1 5500 22.4 72.3 215 8 4 -13.0 -7.1 24.9 76.8 -9.1 30 0.2 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 07/01/2024 at 0900 MDT | 07/01/2024 at 1200 MDT | CAPE... +192.8 LI... -0.7 | CAPE... +178.0 LI... -1.6 CINH... -80.2 K Index... +26.8 | CINH... -15.7 K Index... +28.9 | 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 -63.9 -83.0 235 34 17 2.6 1.4 | -63.4 -82.1 235 42 22 2.0 1.1 45000 -58.0 -72.4 235 50 26 5.7 3.2 | -58.4 -73.1 235 54 28 5.9 3.2 40000 -48.8 -55.8 230 56 29 7.6 4.2 | -48.7 -55.7 230 59 30 7.5 4.1 38000 -44.3 -47.7 225 55 28 7.6 4.2 | -44.2 -47.6 230 59 30 7.5 4.1 36000 -39.7 -39.5 225 53 27 7.5 4.1 | -39.8 -39.6 230 59 30 7.3 4.0 34000 -35.3 -31.5 225 49 25 7.3 4.0 | -35.5 -31.9 230 57 29 7.1 3.9 32000 -31.0 -23.8 230 45 23 7.0 3.9 | -31.3 -24.3 230 54 28 6.7 3.7 30000 -26.2 -15.2 235 43 22 7.2 3.9 | -26.9 -16.4 230 51 26 7.6 4.1 29000 -24.1 -11.4 235 43 22 7.2 3.9 | -24.1 -11.4 230 50 26 7.6 4.2 28000 -22.0 -7.6 235 42 22 6.6 3.6 | -21.9 -7.4 230 48 25 6.3 3.5 27000 -20.0 -4.0 235 41 21 6.7 3.7 | -20.1 -4.2 230 46 24 6.5 3.5 26000 -18.0 -0.4 235 39 20 6.7 3.7 | -18.2 -0.8 230 44 23 6.5 3.6 25000 -16.1 3.0 235 38 20 6.6 3.6 | -16.3 2.7 235 42 22 6.3 3.4 24000 -14.2 6.4 235 36 18 6.4 3.5 | -14.5 5.9 235 39 20 5.9 3.3 23000 -12.3 9.9 235 33 17 6.4 3.5 | -12.8 9.0 235 35 18 6.0 3.3 22000 -10.4 13.3 235 31 16 6.3 3.4 | -11.1 12.0 235 32 17 6.0 3.3 21000 -8.7 16.3 230 28 14 6.0 3.3 | -9.3 15.3 240 29 15 6.2 3.4 20000 -7.0 19.4 230 25 13 6.0 3.3 | -7.5 18.5 240 26 14 6.2 3.4 19500 -6.1 21.0 225 23 12 6.1 3.4 | -6.6 20.1 240 25 13 6.3 3.5 19000 -5.3 22.5 225 22 11 5.4 2.9 | -5.8 21.6 245 24 12 5.4 3.0 18500 -4.5 23.9 225 20 10 5.4 3.0 | -5.0 23.0 250 23 12 5.5 3.0 18000 -3.7 25.3 225 19 10 5.7 3.1 | -4.2 24.4 255 22 11 5.7 3.1 17500 -2.8 27.0 225 17 9 6.1 3.4 | -3.3 26.1 260 21 11 6.0 3.3 17000 -1.5 29.3 225 16 8 6.5 3.6 | -2.4 27.7 260 20 10 5.8 3.2 16500 -0.5 31.1 225 15 8 7.2 4.0 | -1.4 29.5 265 19 10 8.1 4.5 16000 0.6 33.1 225 14 7 7.1 3.9 | -0.2 31.6 265 18 9 8.1 4.4 15500 1.7 35.1 230 13 7 8.3 4.5 | 1.5 34.7 270 17 9 8.1 4.4 15000 2.9 37.2 235 13 7 8.2 4.5 | 2.7 36.9 270 16 8 8.1 4.4 14500 4.2 39.6 240 12 6 8.5 4.7 | 3.9 39.0 270 15 8 8.6 4.7 14000 5.4 41.7 245 12 6 8.6 4.7 | 5.2 41.4 275 14 7 8.7 4.8 13500 6.7 44.1 250 11 6 8.6 4.7 | 6.5 43.7 275 13 7 8.7 4.8 13000 8.0 46.4 260 11 6 8.5 4.7 | 7.7 45.9 275 13 6 8.6 4.7 12500 9.2 48.6 265 11 6 8.5 4.6 | 9.0 48.2 280 12 6 8.7 4.8 12000 10.4 50.7 270 11 6 8.2 4.5 | 10.3 50.5 280 11 6 8.7 4.8 11500 11.6 52.9 275 11 6 8.2 4.5 | 11.6 52.9 280 10 5 8.6 4.7 11000 12.9 55.2 275 12 6 8.0 4.4 | 12.8 55.0 280 10 5 8.0 4.4 10500 14.1 57.4 280 12 6 4.7 2.6 | 13.9 57.0 280 9 5 12.1 6.7 10250 14.3 57.7 280 12 6 5.3 2.9 | 15.0 59.0 280 9 5 13.3 7.3 10000 14.9 58.8 285 13 6 10.0 5.5 | 15.7 60.3 280 9 4 8.4 4.6 9750 15.6 60.1 285 13 7 9.1 5.0 | 16.4 61.5 280 8 4 10.0 5.5 9500 16.3 61.3 285 13 7 8.3 4.5 | 17.0 62.6 275 8 4 8.4 4.6 9250 16.8 62.2 285 13 7 6.1 3.3 | 17.6 63.7 280 8 4 7.8 4.3 9000 17.2 63.0 285 13 6 7.4 4.0 | 18.2 64.8 280 7 4 10.0 5.5 8750 17.8 64.0 285 12 6 8.8 4.8 | 19.0 66.2 280 7 4 11.0 6.0 8500 18.5 65.3 290 12 6 8.0 4.4 | 19.8 67.6 275 7 4 10.3 5.6 8250 19.0 66.2 290 11 6 6.6 3.6 | 20.5 68.9 275 7 4 8.7 4.8 8000 19.5 67.1 290 10 5 7.6 4.2 | 21.2 70.2 280 7 3 9.7 5.3 7750 20.1 68.2 285 10 5 9.7 5.3 | 22.0 71.6 275 6 3 11.5 6.3 7500 20.8 69.4 280 10 5 8.0 4.4 | 22.8 73.0 275 6 3 9.9 5.4 7250 21.3 70.3 280 9 5 5.8 3.2 | 23.4 74.1 275 6 3 7.8 4.3 7000 21.7 71.1 275 8 4 6.5 3.6 | 24.0 75.2 280 6 3 8.8 4.9 6750 22.3 72.1 270 7 4 9.6 5.3 | 24.8 76.6 275 6 3 12.5 6.9 6500 23.0 73.4 265 8 4 8.6 4.7 | 25.8 78.4 270 5 3 11.7 6.4 6250 23.4 74.1 260 7 4 6.5 3.6 | 26.5 79.7 275 5 3 9.9 5.4 6000 23.9 75.0 255 6 3 6.7 3.7 | 27.3 81.1 275 5 3 9.7 5.3 5750 24.3 75.7 250 6 3 8.5 4.6 | 28.0 82.4 275 5 3 12.2 6.7 5500 25.1 77.2 245 6 3 14.2 7.8 | 29.3 84.7 275 4 2 22.1 12.1 07/01/2024 at 1500 MDT | 07/01/2024 at 1800 MDT | CAPE... +228.3 LI... -1.6 | CAPE... +276.1 LI... -2.4 CINH... -12.4 K Index... +31.2 | CINH... -14.0 K Index... +30.1 | 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 -63.5 -82.3 240 46 24 1.7 0.9 | -62.9 -81.2 245 41 21 2.1 1.2 45000 -58.7 -73.7 240 60 31 6.0 3.3 | -58.1 -72.6 240 57 29 5.2 2.9 40000 -49.0 -56.2 230 67 34 7.2 3.9 | -49.3 -56.7 230 68 35 7.5 4.1 38000 -44.7 -48.5 230 67 34 7.2 3.9 | -44.8 -48.6 230 67 35 7.5 4.1 36000 -40.4 -40.7 230 67 35 7.3 4.0 | -40.3 -40.5 230 67 34 7.6 4.2 34000 -35.9 -32.6 230 63 33 7.4 4.1 | -35.6 -32.1 230 65 33 7.9 4.3 32000 -31.5 -24.7 230 59 31 7.3 4.0 | -30.9 -23.6 235 63 32 7.9 4.4 30000 -27.1 -16.8 230 54 28 7.4 4.1 | -26.1 -15.0 235 60 31 7.0 3.9 29000 -24.3 -11.7 230 51 26 7.4 4.1 | -24.0 -11.2 235 59 31 7.1 3.9 28000 -22.2 -8.0 230 49 25 6.6 3.6 | -22.0 -7.6 240 58 30 6.2 3.4 27000 -20.2 -4.4 235 47 24 6.7 3.7 | -20.1 -4.2 240 53 27 6.2 3.4 26000 -18.3 -0.9 235 45 23 6.7 3.7 | -18.3 -0.9 240 48 25 6.3 3.4 25000 -16.3 2.7 240 43 22 6.5 3.6 | -16.5 2.3 245 44 23 6.3 3.4 24000 -14.6 5.7 240 41 21 6.1 3.3 | -14.7 5.5 250 42 22 6.0 3.3 23000 -12.8 9.0 245 38 19 6.1 3.4 | -12.9 8.8 250 40 21 6.0 3.3 22000 -11.0 12.2 250 35 18 6.1 3.4 | -11.1 12.0 255 39 20 5.9 3.2 21000 -9.2 15.4 250 32 17 6.2 3.4 | -9.6 14.7 260 36 18 5.4 2.9 20000 -7.5 18.5 255 30 15 6.2 3.4 | -8.0 17.6 260 33 17 5.4 3.0 19500 -6.6 20.1 255 29 15 6.2 3.4 | -7.3 18.9 265 32 16 5.4 2.9 19000 -5.7 21.7 255 28 14 6.0 3.3 | -6.5 20.3 265 30 15 6.1 3.4 18500 -4.8 23.4 260 27 14 6.0 3.3 | -5.6 21.9 270 29 15 6.2 3.4 18000 -3.9 25.0 260 26 14 6.0 3.3 | -4.7 23.5 270 27 14 6.4 3.5 17500 -3.1 26.4 265 25 13 6.0 3.3 | -3.8 25.2 270 26 13 6.9 3.8 17000 -2.2 28.0 265 24 12 5.9 3.2 | -2.8 27.0 270 24 12 6.8 3.7 16500 -1.3 29.7 270 22 11 6.6 3.6 | -1.7 28.9 270 23 12 8.0 4.4 16000 -0.4 31.3 270 21 11 6.6 3.6 | 0.0 32.0 270 20 11 8.1 4.4 15500 1.1 34.0 270 19 10 7.7 4.2 | 1.2 34.2 270 19 10 9.0 4.9 15000 2.2 36.0 270 18 9 7.6 4.2 | 2.5 36.5 270 18 9 8.9 4.9 14500 3.4 38.1 270 17 9 8.4 4.6 | 3.9 39.0 270 17 9 9.2 5.0 14000 4.6 40.3 270 15 8 8.7 4.7 | 5.2 41.4 270 16 8 9.3 5.1 13500 5.9 42.6 265 14 7 8.9 4.9 | 6.6 43.9 270 16 8 9.3 5.1 13000 7.2 45.0 265 13 7 9.2 5.0 | 8.0 46.4 270 15 8 9.3 5.1 12500 8.6 47.5 260 12 6 9.3 5.1 | 9.3 48.7 265 14 7 9.3 5.1 12000 9.9 49.8 260 11 6 9.4 5.2 | 10.6 51.1 265 13 7 9.0 4.9 11500 11.3 52.3 255 11 6 9.2 5.0 | 12.0 53.6 265 11 6 8.9 4.9 11000 12.5 54.5 250 10 5 8.0 4.4 | 13.1 55.6 260 10 5 7.7 4.2 10500 13.7 56.7 250 9 5 12.3 6.7 | 14.2 57.6 260 9 5 12.1 6.6 10250 14.8 58.6 250 10 5 13.4 7.4 | 15.3 59.5 255 9 4 13.2 7.3 10000 15.5 59.9 250 9 5 8.4 4.6 | 16.0 60.8 255 8 4 8.2 4.5 9750 16.2 61.2 245 9 5 10.1 5.5 | 16.7 62.1 250 8 4 9.8 5.4 9500 17.0 62.6 245 9 5 8.5 4.7 | 17.4 63.3 250 7 4 8.5 4.7 9250 17.5 63.5 240 8 4 7.7 4.2 | 18.0 64.4 245 7 3 7.2 3.9 9000 18.2 64.8 240 7 4 9.7 5.3 | 18.5 65.3 240 6 3 8.9 4.9 8750 19.0 66.2 240 8 4 10.9 6.0 | 19.3 66.7 240 6 3 10.4 5.7 8500 19.7 67.5 240 8 4 10.0 5.5 | 20.0 68.0 235 5 3 9.9 5.4 8250 20.4 68.7 235 7 4 7.7 4.3 | 20.7 69.3 230 5 3 7.7 4.2 8000 21.0 69.8 230 6 3 8.7 4.8 | 21.2 70.2 220 5 2 8.7 4.8 7750 21.7 71.1 230 6 3 10.9 6.0 | 22.0 71.6 220 5 2 11.1 6.1 7500 22.5 72.5 230 7 3 9.5 5.2 | 22.8 73.0 220 5 2 9.8 5.4 7250 23.1 73.6 230 6 3 7.8 4.3 | 23.4 74.1 215 4 2 8.0 4.4 7000 23.7 74.7 225 6 3 8.5 4.6 | 24.0 75.2 210 4 2 8.3 4.5 6750 24.4 75.9 225 6 3 11.0 6.1 | 24.7 76.5 210 4 2 10.9 6.0 6500 25.2 77.4 225 6 3 10.8 5.9 | 25.5 77.9 210 4 2 10.7 5.8 6250 26.0 78.8 225 5 3 9.7 5.3 | 26.2 79.2 210 4 2 9.4 5.2 6000 26.7 80.1 220 5 3 9.6 5.3 | 26.9 80.4 205 4 2 9.4 5.1 5750 27.4 81.3 220 5 3 11.2 6.1 | 27.6 81.7 205 4 2 10.2 5.6 5500 28.4 83.1 225 5 3 17.8 9.7 | 28.5 83.3 210 4 2 14.6 8.0 ________________________________________________________________________________ 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