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Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
350 UXUS97 KGJT 131306 SRGGJT Soaring Forecast National Weather Service Grand Junction, Colorado 706 AM MDT Tuesday, August 13, 2024 This forecast is for Tuesday, August 13, 2024: If the trigger temperature of 80.8 F/27.1 C is reached...then Thermal Soaring Index....................... Poor Maximum rate of lift........................ 79 ft/min (0.4 m/s) Maximum height of thermals.................. 8977 ft MSL (4138 ft AGL) Forecast maximum temperature................... 81.0 F/27.7 C Time of trigger temperature.................... 1600 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................. 7678 ft MSL (2839 ft AGL) Thermal soaring outlook for Wednesday 08/14.... Excellent Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 06:26:21 / 20:11:23 MDT Total possible sunshine........... 13 hr 45 min 1 sec (825 min 1 sec) Altitude of sun at 13:18:52 MDT... 64.87 degrees Upper air data from rawinsonde observation taken on 08/13/2024 at 0600 MDT Freezing level.................. 15423 ft MSL (10584 ft AGL) Convective condensation level... 12292 ft MSL (7453 ft AGL) Lifted condensation level....... 11725 ft MSL (6886 ft AGL) Lifted index.................... -0.9 K index......................... +29.2 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 -66.3 -87.3 245 13 7 6.4 3.5 82.2 180.0 32.0 M M 45000 -58.2 -72.8 240 30 15 6.3 3.4 71.4 160.5 27.6 M M 40000 -51.2 -60.2 220 41 21 6.0 3.3 59.7 139.4 21.7 M M 38000 -47.1 -52.8 215 38 20 7.7 4.2 57.0 134.7 20.4 M M 36000 -42.0 -43.6 205 43 22 6.1 3.4 56.0 132.8 20.2 M M 34000 -36.6 -33.9 210 40 21 8.1 4.4 54.4 129.9 19.6 M M 32000 -32.5 -26.5 205 33 17 5.7 3.1 51.9 125.5 18.2 M M 30000 -27.8 -18.0 220 31 16 7.9 4.4 50.5 122.8 17.5 M M 29000 -25.4 -13.7 220 31 16 8.1 4.4 49.8 121.6 17.2 M M 28000 -23.1 -9.6 225 35 18 7.2 3.9 49.0 120.2 16.8 M M 27000 -20.9 -5.6 225 38 20 7.4 4.0 48.1 118.6 16.3 M M 26000 -18.7 -1.7 225 36 18 7.4 4.1 47.2 116.9 15.7 M M 25000 -16.6 2.1 230 33 17 7.2 4.0 46.3 115.4 15.1 M M 24000 -14.7 5.5 235 28 14 6.4 3.5 45.0 113.1 14.2 M M 23000 -13.3 8.1 235 25 13 5.4 3.0 43.2 109.8 12.8 M M 22000 -11.5 11.3 245 22 11 4.8 2.6 41.9 107.5 11.9 M M 21000 -10.1 13.8 235 19 10 4.5 2.5 40.2 104.4 10.5 M M 20000 -9.1 15.6 250 22 11 4.6 2.5 37.9 100.3 8.6 M M 19500 -8.5 16.7 250 23 12 4.2 2.3 37.0 98.6 7.8 M M 19000 -7.7 18.1 245 23 12 8.4 4.6 36.3 97.3 7.2 M M 18500 -5.8 21.6 250 25 13 5.3 2.9 36.0 96.8 7.0 M M 18000 -5.2 22.6 250 23 12 3.9 2.1 35.0 95.0 6.1 M M 17500 -4.2 24.4 250 22 11 9.7 5.3 34.5 94.1 5.7 M M 17000 -2.9 26.8 245 21 11 8.3 4.6 34.4 93.9 5.6 M M 16500 -1.8 28.8 250 22 11 7.3 4.0 34.1 93.3 5.2 M M 16000 -0.9 30.4 245 21 11 6.2 3.4 33.5 92.3 4.7 M M 15500 -0.0 32.0 245 22 11 6.2 3.4 32.9 91.2 4.2 M M 15000 0.9 33.6 250 22 11 6.3 3.4 32.3 90.2 3.6 M M 14500 1.8 35.2 245 20 10 6.8 3.7 31.7 89.1 3.1 M M 14000 2.9 37.2 245 15 8 7.4 4.1 31.4 88.4 2.7 M M 13500 4.0 39.2 250 14 7 7.5 4.1 31.0 87.8 2.4 M M 13000 5.0 41.0 245 15 8 7.9 4.3 30.6 87.1 2.0 M M 12500 6.0 42.8 240 16 8 6.6 3.6 30.1 86.1 1.5 M M 12000 7.3 45.1 240 15 8 8.6 4.7 29.9 85.8 1.3 M M 11500 8.6 47.5 240 14 7 8.7 4.8 29.7 85.5 1.2 M M 11000 9.9 49.8 240 16 8 8.7 4.8 29.6 85.2 1.0 M M 10500 11.1 52.0 230 13 6 8.6 4.7 29.4 84.9 0.9 M M 10250 11.8 53.2 225 10 5 8.1 4.4 29.3 84.7 0.7 M M 10000 12.3 54.1 205 8 4 8.0 4.4 29.1 84.5 0.6 M M 9750 12.9 55.2 205 8 4 8.0 4.4 29.0 84.2 0.5 M M 9500 13.5 56.3 200 9 4 8.1 4.4 28.9 84.0 0.3 M M 9250 14.1 57.4 200 10 5 7.8 4.3 28.7 83.7 0.2 M M 9000 14.7 58.5 200 11 6 9.0 4.9 28.6 83.5 0.0 M M 8750 15.3 59.5 190 10 5 4.6 2.5 28.5 83.2 -0.1 259 1.3 8500 15.4 59.7 165 8 4 2.1 1.1 27.8 82.1 -0.7 248 1.3 8250 15.7 60.3 155 9 5 8.0 4.4 27.5 81.5 -1.1 230 1.2 8000 16.2 61.2 150 10 5 4.0 2.2 27.3 81.2 -1.4 208 1.1 7750 16.0 60.8 150 10 5 -7.0 -3.9 26.4 79.6 -2.3 208 1.1 7500 15.3 59.5 150 8 4 -3.6 -2.0 25.1 77.2 -3.8 221 1.1 7250 15.4 59.7 150 7 4 6.7 3.7 24.5 76.2 -4.4 211 1.1 7000 15.9 60.6 135 6 3 6.4 3.5 24.3 75.8 -4.6 189 1.0 6750 16.2 61.2 120 5 3 4.7 2.6 24.0 75.2 -5.0 171 0.9 6500 16.5 61.7 100 3 1 2.1 1.2 23.6 74.4 -5.5 155 0.8 6250 16.6 61.9 040 2 1 1.6 0.9 22.9 73.2 -6.1 145 0.7 6000 16.8 62.2 355 2 1 4.2 2.3 22.4 72.3 -6.7 131 0.7 5750 17.1 62.8 355 2 1 4.0 2.2 22.0 71.6 -7.1 115 0.6 5500 17.4 63.3 055 2 1 4.2 2.3 21.6 70.8 -7.6 100 0.5 5250 17.6 63.7 090 3 1 3.9 2.2 21.1 70.0 -8.1 85 0.4 5000 17.9 64.2 110 3 2 4.8 2.6 20.7 69.3 -8.6 69 0.4 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 08/13/2024 at 0900 MDT | 08/13/2024 at 1200 MDT | CAPE... +286.8 LI... -2.0 | CAPE... +655.1 LI... -2.6 CINH... -57.3 K Index... +31.2 | CINH... -5.0 K Index... +31.8 | 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 -62.8 -81.0 230 19 10 1.8 1.0 | -62.4 -80.3 225 22 11 1.6 0.9 45000 -58.3 -72.9 225 26 14 5.1 2.8 | -58.1 -72.6 220 29 15 5.2 2.8 40000 -50.4 -58.7 215 38 20 6.5 3.6 | -50.2 -58.4 215 37 19 6.4 3.5 38000 -46.5 -51.7 210 39 20 6.5 3.6 | -46.3 -51.3 215 38 20 6.4 3.5 36000 -42.1 -43.8 210 39 20 6.9 3.8 | -42.0 -43.6 210 40 20 6.7 3.7 34000 -37.7 -35.9 210 37 19 7.4 4.1 | -37.7 -35.9 215 37 19 7.2 4.0 32000 -33.2 -27.8 210 34 18 8.2 4.5 | -33.4 -28.1 215 35 18 8.0 4.4 30000 -28.8 -19.8 215 32 16 7.5 4.1 | -28.9 -20.0 210 32 16 7.6 4.2 29000 -26.5 -15.7 215 31 16 7.5 4.1 | -26.7 -16.1 210 30 15 7.6 4.2 28000 -24.3 -11.7 220 29 15 7.6 4.2 | -24.4 -11.9 210 28 15 7.3 4.0 27000 -22.0 -7.6 220 27 14 7.7 4.2 | -22.3 -8.1 210 27 14 7.2 3.9 26000 -19.8 -3.6 220 25 13 7.7 4.2 | -20.2 -4.4 210 26 14 7.2 3.9 25000 -17.5 0.5 220 23 12 7.7 4.2 | -18.1 -0.6 205 25 13 7.2 3.9 24000 -15.6 3.9 220 22 12 6.3 3.5 | -16.0 3.2 210 24 12 7.1 3.9 23000 -13.8 7.2 220 22 11 6.4 3.5 | -13.9 7.0 210 22 11 7.2 3.9 22000 -11.5 11.3 225 22 11 6.1 3.3 | -11.4 11.5 215 19 10 6.3 3.5 21000 -9.8 14.4 225 21 11 6.0 3.3 | -9.6 14.7 220 19 10 5.9 3.3 20000 -8.0 17.6 225 21 11 6.0 3.3 | -7.9 17.8 220 18 9 6.0 3.3 19500 -7.2 19.0 220 20 10 5.9 3.2 | -7.1 19.2 225 18 9 5.9 3.2 19000 -6.4 20.5 220 20 10 5.1 2.8 | -6.3 20.7 225 18 9 5.4 3.0 18500 -5.7 21.7 220 20 10 5.2 2.8 | -5.5 22.1 225 18 9 5.4 3.0 18000 -4.9 23.2 220 19 10 5.6 3.0 | -4.7 23.5 230 18 9 5.3 2.9 17500 -4.1 24.6 220 19 10 5.7 3.1 | -4.0 24.8 230 18 9 5.2 2.9 17000 -3.3 26.1 220 18 10 5.8 3.2 | -3.2 26.2 230 18 9 5.3 2.9 16500 -2.4 27.7 220 18 9 6.2 3.4 | -2.4 27.7 230 18 9 5.9 3.2 16000 -1.5 29.3 220 18 9 6.1 3.4 | -1.6 29.1 235 18 9 5.8 3.2 15500 -0.6 30.9 220 18 9 6.5 3.6 | -0.8 30.6 235 17 9 6.0 3.3 15000 0.3 32.5 220 17 9 6.5 3.6 | 0.1 32.2 235 17 9 6.1 3.3 14500 1.2 34.2 220 17 9 6.7 3.7 | 0.9 33.6 235 17 9 6.3 3.5 14000 2.2 36.0 220 17 9 6.8 3.7 | 1.9 35.4 235 17 9 6.5 3.6 13500 3.1 37.6 220 16 8 6.9 3.8 | 2.8 37.0 235 17 9 6.7 3.7 13000 4.2 39.6 220 16 8 7.2 4.0 | 3.8 38.8 235 16 8 7.0 3.9 12500 5.2 41.4 220 16 8 7.2 4.0 | 4.8 40.6 235 16 8 7.1 3.9 12000 6.2 43.2 220 15 8 7.4 4.1 | 5.8 42.4 235 15 8 7.4 4.1 11500 7.3 45.1 220 15 8 7.4 4.1 | 6.9 44.4 235 14 7 7.4 4.1 11000 8.4 47.1 220 14 7 7.2 3.9 | 8.0 46.4 235 14 7 7.4 4.1 10500 9.4 48.9 215 14 7 6.0 3.3 | 9.0 48.2 235 14 7 6.1 3.3 10250 9.8 49.6 215 13 7 5.7 3.1 | 9.4 48.9 235 14 7 5.6 3.1 10000 10.3 50.5 215 13 7 7.9 4.3 | 9.9 49.8 235 14 7 8.0 4.4 9750 10.8 51.4 215 13 7 8.1 4.4 | 10.5 50.9 235 13 7 8.4 4.6 9500 11.4 52.5 210 13 7 7.9 4.3 | 11.1 52.0 235 13 7 7.9 4.4 9250 12.0 53.6 210 13 7 7.2 4.0 | 11.6 52.9 235 12 6 6.2 3.4 9000 12.4 54.3 210 12 6 6.5 3.6 | 12.0 53.6 240 12 6 6.6 3.6 8750 12.9 55.2 210 12 6 6.3 3.5 | 12.5 54.5 240 12 6 8.1 4.4 8500 13.4 56.1 205 12 6 6.3 3.5 | 13.1 55.6 240 11 6 7.1 3.9 8250 13.8 56.8 205 12 6 6.3 3.4 | 13.8 56.8 245 9 5 6.2 3.4 8000 14.7 58.5 200 10 5 6.2 3.4 | 14.4 57.9 245 9 4 9.3 5.1 7750 15.1 59.2 195 10 5 6.0 3.3 | 15.0 59.0 245 8 4 7.3 4.0 7500 15.5 59.9 195 9 5 5.6 3.1 | 15.4 59.7 250 7 4 4.4 2.4 7250 15.9 60.6 190 8 4 5.9 3.2 | 15.7 60.3 255 6 3 5.5 3.0 7000 16.4 61.5 190 7 4 7.6 4.1 | 16.3 61.3 260 6 3 10.4 5.7 6750 17.0 62.6 185 6 3 6.8 3.7 | 17.1 62.8 260 6 3 8.9 4.9 6500 17.4 63.3 185 6 3 5.3 2.9 | 17.5 63.5 270 5 2 5.1 2.8 6250 17.8 64.0 180 5 2 5.6 3.1 | 17.9 64.2 285 4 2 5.7 3.2 6000 18.2 64.8 175 4 2 7.8 4.3 | 18.3 64.9 295 4 2 10.4 5.7 5750 18.8 65.8 175 3 1 11.3 6.2 | 19.4 66.9 290 3 2 19.5 10.7 5500 19.4 66.9 175 2 1 0.9 0.5 | 20.3 68.5 310 3 2 -1.6 -0.9 5250 M M M M M M M | M M M M M M M 5000 M M M M M M M | M M M M M M M 08/13/2024 at 1500 MDT | 08/13/2024 at 1800 MDT | CAPE... +761.2 LI... -3.1 | CAPE... +482.9 LI... -3.1 CINH... -7.2 K Index... +31.4 | CINH... -54.6 K Index... +29.7 | 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 -62.4 -80.3 230 22 11 2.1 1.1 | -62.7 -80.9 235 20 10 2.0 1.1 45000 -57.8 -72.0 225 29 15 5.1 2.8 | -57.8 -72.0 230 26 13 5.5 3.0 40000 -50.0 -58.0 215 32 17 6.2 3.4 | -49.5 -57.1 225 30 15 6.0 3.3 38000 -45.8 -50.4 215 32 17 6.2 3.4 | -45.5 -49.9 220 31 16 6.0 3.3 36000 -42.1 -43.8 210 32 17 6.6 3.6 | -41.9 -43.4 215 32 17 6.4 3.5 34000 -37.7 -35.9 210 33 17 7.3 4.0 | -37.7 -35.9 220 33 17 7.0 3.9 32000 -33.3 -27.9 210 33 17 7.9 4.4 | -33.5 -28.3 220 34 17 7.3 4.0 30000 -28.8 -19.8 210 30 15 7.6 4.2 | -29.1 -20.4 220 31 16 7.5 4.1 29000 -26.6 -15.9 210 28 15 7.6 4.2 | -26.8 -16.2 220 29 15 7.5 4.1 28000 -24.3 -11.7 215 27 14 7.1 3.9 | -24.6 -12.3 220 28 14 7.4 4.1 27000 -22.3 -8.1 215 26 13 6.8 3.7 | -22.4 -8.3 225 27 14 7.4 4.1 26000 -20.3 -4.5 220 25 13 6.8 3.8 | -20.2 -4.4 230 26 13 7.4 4.1 25000 -18.2 -0.8 220 24 12 6.9 3.8 | -18.0 -0.4 230 26 13 7.4 4.1 24000 -16.3 2.7 225 23 12 6.6 3.6 | -15.9 3.4 235 25 13 6.8 3.7 23000 -13.8 7.2 230 23 12 6.7 3.7 | -13.4 7.9 240 24 13 6.9 3.8 22000 -11.9 10.6 235 23 12 6.5 3.6 | -11.5 11.3 245 24 12 5.9 3.2 21000 -10.0 14.0 240 22 11 6.4 3.5 | -9.9 14.2 245 22 11 5.4 3.0 20000 -8.1 17.4 240 21 11 6.4 3.5 | -8.4 16.9 250 20 10 5.5 3.0 19500 -7.2 19.0 240 21 11 6.4 3.5 | -7.6 18.3 250 19 10 5.6 3.1 19000 -6.3 20.7 240 20 10 6.2 3.4 | -6.7 19.9 250 19 10 6.4 3.5 18500 -5.4 22.3 245 20 10 6.2 3.4 | -5.8 21.6 250 18 9 6.4 3.5 18000 -4.6 23.7 245 20 10 5.7 3.1 | -4.9 23.2 255 18 9 6.4 3.5 17500 -3.8 25.2 245 19 10 5.5 3.0 | -4.0 24.8 255 18 9 6.4 3.5 17000 -3.0 26.6 250 19 10 5.6 3.0 | -3.1 26.4 260 18 9 6.4 3.5 16500 -2.2 28.0 250 19 10 5.9 3.2 | -2.1 28.2 260 18 9 7.1 3.9 16000 -1.4 29.5 250 18 9 5.8 3.2 | -1.1 30.0 260 17 9 7.0 3.8 15500 -0.5 31.1 250 18 9 6.6 3.6 | -0.1 31.8 265 17 9 7.5 4.1 15000 0.4 32.7 250 18 9 6.7 3.7 | 1.0 33.8 265 17 9 7.5 4.1 14500 1.4 34.5 255 18 9 6.9 3.8 | 2.1 35.8 265 17 9 7.8 4.3 14000 2.4 36.3 255 17 9 7.0 3.9 | 3.3 37.9 265 16 8 8.0 4.4 13500 3.4 38.1 255 17 9 7.2 4.0 | 4.4 39.9 265 16 8 8.0 4.4 13000 4.4 39.9 255 17 9 7.5 4.1 | 5.6 42.1 265 15 8 8.1 4.4 12500 5.5 41.9 250 16 8 7.5 4.1 | 6.8 44.2 265 15 8 8.1 4.5 12000 6.6 43.9 250 16 8 7.6 4.2 | 8.0 46.4 260 14 7 8.3 4.6 11500 7.7 45.9 250 16 8 7.6 4.2 | 9.2 48.6 260 13 7 8.3 4.6 11000 8.8 47.8 250 15 8 7.7 4.2 | 10.4 50.7 255 12 6 8.0 4.4 10500 9.9 49.8 250 14 7 6.2 3.4 | 11.6 52.9 250 12 6 6.7 3.7 10250 10.3 50.5 245 14 7 6.5 3.6 | 12.0 53.6 245 12 6 7.1 3.9 10000 10.9 51.6 250 14 7 8.9 4.9 | 12.6 54.7 245 11 6 9.1 5.0 9750 11.5 52.7 250 13 7 8.5 4.7 | 13.2 55.8 245 11 6 8.6 4.7 9500 12.2 54.0 250 12 6 8.3 4.6 | 13.8 56.8 240 10 5 8.6 4.7 9250 12.7 54.9 250 11 6 7.2 3.9 | 14.4 57.9 240 10 5 7.4 4.0 9000 13.2 55.8 250 11 6 7.6 4.2 | 14.8 58.6 240 9 5 7.6 4.1 8750 13.8 56.8 250 10 5 8.6 4.7 | 15.4 59.7 240 9 4 8.6 4.7 8500 14.4 57.9 250 9 5 7.8 4.3 | 16.5 61.7 235 7 4 5.6 3.1 8250 15.3 59.5 255 7 4 7.0 3.8 | 16.9 62.4 235 6 3 6.5 3.5 8000 15.9 60.6 255 6 3 10.0 5.5 | 17.5 63.5 225 5 3 9.7 5.3 7750 16.6 61.9 260 6 3 8.0 4.4 | 18.2 64.8 215 4 2 8.0 4.4 7500 17.1 62.8 260 4 2 5.0 2.7 | 18.6 65.5 205 4 2 5.1 2.8 7250 17.4 63.3 265 3 2 6.0 3.3 | 19.0 66.2 180 3 2 5.3 2.9 7000 18.0 64.4 265 2 1 10.6 5.8 | 19.5 67.1 160 3 2 8.5 4.7 6750 18.8 65.8 260 2 1 10.3 5.7 | 20.1 68.2 150 3 2 9.4 5.1 6500 19.3 66.7 270 2 1 7.9 4.3 | 20.8 69.4 140 3 2 8.5 4.7 6250 19.9 67.8 285 1 1 7.9 4.3 | 21.4 70.5 130 3 2 8.4 4.6 6000 20.5 68.9 300 1 1 12.4 6.8 | 22.0 71.6 125 3 2 8.7 4.8 5750 21.8 71.2 285 1 1 22.6 12.4 | 22.7 72.9 125 3 1 12.2 6.7 5500 23.1 73.6 330 1 1 6.1 3.4 | 23.8 74.8 115 3 1 18.9 10.4 5250 M M M M M M M | M M M M M M M 5000 M M M M M M M | M M M M M M M ________________________________________________________________________________ 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 at Walker Field in Grand Junction, Colorado at North Latitude: 39 deg 07 min 00.001 sec West Longitude: 108 deg 31 min 59.998 sec Elevation: 4839 feet (1475 meters) and may not be representative of other areas along the Western Slope of Colorado. 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