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Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000 UXUS97 KGJT 191307 SRGGJT Soaring Forecast National Weather Service Grand Junction, Colorado 707 AM MDT Friday, April 19, 2024 This forecast is for Friday, April 19, 2024: If the trigger temperature of 65.0 F/18.3 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1309 ft/min (6.7 m/s) Maximum height of thermals.................. 19115 ft MSL (14286 ft AGL) Forecast maximum temperature................... 77.0 F/25.5 C Time of trigger temperature.................... 1000 MDT Time of overdevelopment........................ 1700 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 15378 ft MSL (10548 ft AGL) Thermal soaring outlook for Saturday 04/20..... Excellent Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 06:30:23 / 19:55:47 MDT Total possible sunshine........... 13 hr 25 min 23 sec (805 min 23 sec) Altitude of sun at 13:13:05 MDT... 62.27 degrees Upper air data from rawinsonde observation taken on 04/19/2024 at 0600 MDT Freezing level.................. 11599 ft MSL (6770 ft AGL) Convective condensation level... 16955 ft MSL (12126 ft AGL) Lifted condensation level....... 17928 ft MSL (13099 ft AGL) Lifted index.................... +0.9 K index......................... +18.0 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 -55.9 -68.6 255 58 30 3.4 1.9 107.2 225.0 47.0 M M 45000 -56.0 -68.8 255 67 34 2.0 1.1 82.4 180.4 35.1 M M 40000 -57.3 -71.1 255 73 38 3.9 2.1 56.1 133.0 20.4 M M 38000 -57.0 -70.6 260 73 38 3.3 1.8 47.8 118.0 15.3 M M 36000 -54.2 -65.6 255 69 36 6.8 3.8 43.4 110.1 12.7 M M 34000 -51.1 -60.0 260 52 27 3.4 1.9 39.4 102.9 10.2 M M 32000 -47.4 -53.3 260 51 26 9.1 5.0 36.4 97.6 8.3 M M 30000 -42.0 -43.6 260 51 26 9.2 5.0 35.9 96.6 8.1 M M 29000 -38.7 -37.7 255 53 27 8.8 4.8 35.5 95.9 7.9 M M 28000 -36.1 -33.0 255 57 29 7.9 4.3 35.1 95.2 7.7 M M 27000 -34.0 -29.2 250 51 26 8.0 4.4 34.0 93.1 6.9 M M 26000 -31.6 -24.9 245 46 24 8.0 4.4 33.3 91.9 6.5 M M 25000 -29.3 -20.7 260 46 24 7.7 4.2 32.6 90.6 5.9 M M 24000 -27.1 -16.8 265 41 21 6.2 3.4 31.7 89.0 5.3 M M 23000 -25.4 -13.7 260 44 23 5.8 3.2 30.2 86.4 4.1 M M 22000 -23.6 -10.5 260 46 24 6.5 3.5 28.9 84.0 3.1 M M 21000 -21.7 -7.1 260 46 24 7.0 3.9 27.7 81.9 2.1 M M 20000 -20.2 -4.4 240 38 20 7.6 4.1 25.9 78.7 0.7 M M 19500 -19.1 -2.4 240 38 19 7.2 3.9 25.5 77.9 0.3 M M 19000 -18.0 -0.4 250 36 19 7.9 4.4 25.0 77.1 -0.0 1304 6.6 18500 -16.9 1.6 250 35 18 6.6 3.6 24.7 76.4 -0.3 1255 6.4 18000 -15.9 3.4 250 34 17 6.3 3.5 24.1 75.4 -0.9 1213 6.2 17500 -15.0 5.0 245 32 17 7.1 3.9 23.5 74.3 -1.4 1170 5.9 17000 -13.9 7.0 245 32 16 7.6 4.2 23.2 73.7 -1.7 1121 5.7 16500 -12.8 9.0 250 29 15 7.7 4.2 22.8 73.0 -2.1 1073 5.5 16000 -11.6 11.1 260 25 13 7.8 4.3 22.5 72.4 -2.4 1025 5.2 15500 -10.0 14.0 255 24 12 7.9 4.3 22.0 71.6 -3.0 953 4.8 15000 -8.9 16.0 250 26 13 8.2 4.5 21.7 71.0 -3.4 904 4.6 14500 -7.5 18.5 245 25 13 9.5 5.2 21.6 70.9 -3.5 849 4.3 14000 -6.2 20.8 245 21 11 8.9 4.9 21.5 70.6 -3.6 795 4.0 13500 -4.9 23.2 245 20 10 8.8 4.8 21.3 70.4 -3.8 741 3.8 13000 -3.6 25.5 250 21 11 8.8 4.8 21.2 70.1 -3.9 687 3.5 12500 -2.2 28.0 255 22 11 8.8 4.8 21.0 69.9 -4.1 632 3.2 12000 -0.9 30.4 255 24 12 8.8 4.8 20.9 69.6 -4.2 578 2.9 11500 0.4 32.7 260 22 12 8.8 4.8 20.7 69.3 -4.4 524 2.7 11000 1.7 35.1 265 21 11 8.8 4.8 20.6 69.0 -4.6 470 2.4 10500 3.0 37.4 255 17 9 8.9 4.9 20.4 68.7 -4.8 416 2.1 10250 3.7 38.7 255 16 8 8.3 4.6 20.3 68.6 -4.9 389 2.0 10000 4.2 39.6 245 15 8 6.7 3.7 20.1 68.2 -5.1 365 1.9 9750 4.7 40.5 250 12 6 6.1 3.3 19.8 67.7 -5.4 343 1.7 9500 5.1 41.2 255 9 5 6.2 3.4 19.6 67.2 -5.6 322 1.6 9250 5.6 42.1 270 7 4 6.2 3.4 19.3 66.7 -5.9 301 1.5 9000 6.1 43.0 295 5 3 6.2 3.4 19.0 66.2 -6.2 280 1.4 8750 6.5 43.7 280 4 2 6.0 3.3 18.7 65.7 -6.5 259 1.3 8500 7.0 44.6 215 5 2 6.8 3.8 18.5 65.2 -6.8 237 1.2 8250 7.6 45.7 245 4 2 7.7 4.2 18.3 64.9 -7.0 213 1.1 8000 8.1 46.6 245 4 2 7.5 4.1 18.1 64.6 -7.1 189 1.0 7750 8.7 47.7 230 4 2 7.5 4.1 18.0 64.3 -7.3 165 0.8 7500 9.2 48.6 210 3 2 7.5 4.1 17.8 64.0 -7.5 140 0.7 7250 9.8 49.6 175 4 2 7.5 4.1 17.6 63.7 -7.7 116 0.6 7000 10.4 50.7 150 6 3 7.5 4.1 17.4 63.4 -7.9 92 0.5 6750 10.9 51.6 165 4 2 7.5 4.1 17.3 63.1 -8.0 67 0.3 6500 11.5 52.7 260 1 1 7.6 4.2 17.1 62.8 -8.2 43 0.2 6250 12.1 53.8 300 4 2 7.2 3.9 16.9 62.5 -8.4 19 0.1 6000 12.6 54.7 285 4 2 5.5 3.0 16.7 62.0 -8.7 M M 5750 12.9 55.2 280 5 3 4.6 2.5 16.3 61.3 -9.1 M M 5500 13.3 55.9 275 7 4 5.0 2.8 15.9 60.7 -9.5 M M 5250 13.7 56.7 275 7 4 4.1 2.3 15.5 60.0 -9.8 M M 5000 13.8 56.8 290 5 3 -0.5 -0.3 15.0 59.0 -10.4 M M * * * * * * Numerical weather prediction model forecast data valid * * * * * * 04/19/2024 at 0900 MDT | 04/19/2024 at 1200 MDT | CAPE... 0.0 LI... +0.5 | CAPE... +2.0 LI... +0.6 CINH... -0.1 K Index... +21.9 | CINH... -4.3 K Index... +22.7 | 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 -56.6 -69.9 260 48 25 1.8 1.0 | -56.5 -69.7 260 46 24 1.7 1.0 45000 -54.1 -65.4 255 58 30 -2.2 -1.2 | -54.0 -65.2 255 55 28 -1.6 -0.9 40000 -58.4 -73.1 260 65 34 -2.9 -1.6 | -57.5 -71.5 250 65 33 -2.3 -1.3 38000 -57.1 -70.8 260 66 34 5.3 2.9 | -56.7 -70.1 250 64 33 3.6 2.0 36000 -53.9 -65.0 260 64 33 5.3 2.9 | -54.5 -66.1 250 60 31 3.6 2.0 34000 -50.5 -58.9 260 61 31 6.4 3.5 | -51.7 -61.1 250 56 29 7.0 3.8 32000 -46.7 -52.1 260 54 28 6.4 3.5 | -47.5 -53.5 255 53 27 7.1 3.9 30000 -42.6 -44.7 260 49 25 8.1 4.4 | -43.0 -45.4 255 51 26 8.4 4.6 29000 -40.1 -40.2 260 49 25 8.1 4.4 | -40.5 -40.9 260 51 26 8.4 4.6 28000 -37.7 -35.9 260 49 25 8.1 4.5 | -38.0 -36.4 260 50 26 8.4 4.6 27000 -35.3 -31.5 260 49 25 8.0 4.4 | -35.5 -31.9 260 50 26 8.2 4.5 26000 -32.9 -27.2 260 49 25 8.0 4.4 | -33.1 -27.6 260 50 26 8.1 4.4 25000 -30.5 -22.9 260 48 25 8.0 4.4 | -30.7 -23.3 260 50 26 8.1 4.5 24000 -27.7 -17.9 260 48 25 6.4 3.5 | -28.3 -18.9 260 49 25 7.6 4.2 23000 -25.8 -14.4 260 47 24 6.3 3.5 | -25.7 -14.3 260 47 24 6.7 3.7 22000 -23.9 -11.0 260 45 23 6.4 3.5 | -23.8 -10.8 260 46 23 6.7 3.7 21000 -22.0 -7.6 260 44 23 6.5 3.6 | -21.8 -7.2 260 43 22 6.8 3.7 20000 -20.1 -4.2 260 41 21 6.5 3.6 | -19.8 -3.6 260 41 21 6.8 3.7 19500 -19.1 -2.4 260 40 21 6.5 3.6 | -18.8 -1.8 260 39 20 6.8 3.7 19000 -18.2 -0.8 260 39 20 6.4 3.5 | -17.8 -0.0 260 38 19 6.8 3.7 18500 -17.2 1.0 260 37 19 7.2 4.0 | -16.8 1.8 260 36 19 7.0 3.9 18000 -16.1 3.0 260 35 18 7.2 3.9 | -15.7 3.7 260 35 18 7.0 3.8 17500 -15.1 4.8 260 32 17 7.2 4.0 | -14.7 5.5 255 33 17 7.1 3.9 17000 -14.0 6.8 260 30 16 7.3 4.0 | -13.6 7.5 255 31 16 7.2 3.9 16500 -12.9 8.8 260 28 15 7.3 4.0 | -12.6 9.3 255 29 15 7.2 4.0 16000 -11.8 10.8 260 27 14 7.5 4.1 | -11.5 11.3 255 28 14 7.3 4.0 15500 -10.8 12.6 260 26 13 7.4 4.1 | -10.5 13.1 255 26 13 7.3 4.0 15000 -9.6 14.7 260 25 13 7.9 4.3 | -9.4 15.1 250 24 13 7.3 4.0 14500 -8.5 16.7 265 24 12 7.9 4.3 | -8.3 17.1 250 23 12 7.2 4.0 14000 -7.3 18.9 265 23 12 8.4 4.6 | -7.2 19.0 250 22 11 7.9 4.3 13500 -6.0 21.2 265 22 12 8.5 4.7 | -6.0 21.2 250 20 10 8.1 4.5 13000 -4.7 23.5 265 22 11 8.6 4.7 | -4.8 23.4 250 19 10 8.6 4.7 12500 -3.4 25.9 265 21 11 8.7 4.8 | -3.5 25.7 250 18 9 8.9 4.9 12000 -2.2 28.0 265 20 10 8.7 4.7 | -2.2 28.0 250 17 9 9.1 5.0 11500 -0.9 30.4 265 19 10 8.5 4.7 | -0.8 30.6 250 16 8 9.2 5.0 11000 0.4 32.7 265 18 9 7.8 4.3 | 0.6 33.1 250 15 8 8.4 4.6 10500 1.5 34.7 265 17 9 6.2 3.4 | 1.7 35.1 250 15 8 6.6 3.6 10250 2.0 35.6 265 17 9 10.6 5.8 | 2.3 36.1 250 15 8 11.2 6.1 10000 3.0 37.4 265 15 8 11.1 6.1 | 3.3 37.9 250 13 7 12.1 6.6 9750 3.6 38.5 260 14 7 6.8 3.7 | 3.9 39.0 250 13 6 7.9 4.3 9500 4.1 39.4 260 13 7 8.3 4.5 | 4.6 40.3 250 12 6 9.7 5.3 9250 4.7 40.5 260 12 6 6.6 3.6 | 5.3 41.5 250 11 6 6.9 3.8 9000 5.2 41.4 260 11 6 5.8 3.2 | 5.7 42.3 255 11 5 7.3 4.0 8750 6.2 43.2 255 8 4 7.9 4.3 | 6.4 43.5 255 10 5 9.9 5.4 8500 6.8 44.2 250 7 4 6.7 3.7 | 7.1 44.8 255 9 4 9.6 5.2 8250 7.2 45.0 245 5 3 5.1 2.8 | 8.4 47.1 255 7 3 7.2 3.9 8000 7.6 45.7 240 4 2 6.2 3.4 | 9.0 48.2 260 6 3 9.5 5.2 7750 8.1 46.6 235 3 2 7.5 4.1 | 9.8 49.6 260 6 3 11.2 6.2 7500 8.7 47.7 225 3 1 5.9 3.2 | 10.6 51.1 255 5 3 9.0 5.0 7250 9.0 48.2 215 2 1 4.2 2.3 | 11.1 52.0 265 5 2 7.2 3.9 7000 9.4 48.9 200 2 1 7.1 3.9 | 11.8 53.2 270 4 2 10.6 5.8 6750 10.0 50.0 175 1 1 8.8 4.8 | 12.7 54.9 265 4 2 12.4 6.8 6500 10.6 51.1 150 1 1 7.3 4.0 | 13.5 56.3 260 4 2 10.1 5.5 6250 11.1 52.0 130 1 1 6.9 3.8 | 14.2 57.6 270 4 2 9.6 5.3 6000 11.6 52.9 110 1 1 7.2 4.0 | 15.0 59.0 275 3 2 8.7 4.8 5750 12.3 54.1 090 1 0 11.4 6.2 | 15.7 60.3 265 4 2 13.9 7.6 5500 13.7 56.7 095 1 1 30.7 16.9 | 18.1 64.6 280 3 1 61.0 33.5 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 04/19/2024 at 1500 MDT | 04/19/2024 at 1800 MDT | CAPE... +17.1 LI... -0.1 | CAPE... +11.7 LI... -0.0 CINH... -11.3 K Index... +21.3 | CINH... -8.3 K Index... +21.2 | 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 -56.6 -69.9 260 45 23 1.2 0.7 | -55.9 -68.6 260 45 23 0.7 0.4 45000 -54.9 -66.8 255 52 27 -1.2 -0.7 | -55.0 -67.0 260 53 27 -1.6 -0.9 40000 -57.4 -71.3 250 64 33 -1.7 -0.9 | -58.2 -72.8 255 64 33 -2.2 -1.2 38000 -56.7 -70.1 250 63 32 2.9 1.6 | -57.6 -71.7 255 63 33 3.2 1.8 36000 -55.0 -67.0 250 57 29 2.9 1.6 | -55.7 -68.3 255 59 30 3.2 1.8 34000 -52.5 -62.5 250 52 27 6.8 3.8 | -53.0 -63.4 255 54 28 7.4 4.1 32000 -48.4 -55.1 255 50 26 6.9 3.8 | -48.5 -55.3 250 51 26 7.5 4.1 30000 -43.8 -46.8 255 48 25 9.3 5.1 | -43.7 -46.7 250 48 25 8.7 4.8 29000 -41.0 -41.8 255 49 25 9.3 5.1 | -41.2 -42.2 250 47 24 8.7 4.8 28000 -38.2 -36.8 255 49 25 9.3 5.1 | -38.6 -37.5 255 45 23 8.7 4.8 27000 -35.5 -31.9 255 49 25 8.4 4.6 | -36.0 -32.8 255 44 23 8.5 4.7 26000 -33.1 -27.6 255 49 25 8.2 4.5 | -33.4 -28.1 255 44 23 8.5 4.7 25000 -30.6 -23.1 255 49 25 8.2 4.5 | -30.9 -23.6 260 44 23 8.5 4.7 24000 -28.1 -18.6 255 49 25 7.7 4.2 | -28.4 -19.1 260 44 23 7.9 4.3 23000 -25.6 -14.1 260 45 23 6.9 3.8 | -25.7 -14.3 260 41 21 7.0 3.8 22000 -23.5 -10.3 260 43 22 6.9 3.8 | -23.7 -10.7 260 38 19 7.0 3.9 21000 -21.5 -6.7 260 40 20 6.5 3.6 | -21.6 -6.9 260 35 18 7.1 3.9 20000 -19.5 -3.1 260 36 19 6.6 3.6 | -19.5 -3.1 255 31 16 7.1 3.9 19500 -18.6 -1.5 260 34 18 6.6 3.6 | -18.4 -1.1 255 30 15 7.1 3.9 19000 -17.6 0.3 255 33 17 6.5 3.6 | -17.4 0.7 255 28 14 7.1 3.9 18500 -16.6 2.1 255 31 16 7.7 4.2 | -16.3 2.7 250 27 14 7.7 4.2 18000 -15.4 4.3 255 30 15 7.6 4.2 | -15.2 4.6 250 26 13 7.7 4.2 17500 -14.3 6.3 250 28 15 7.7 4.2 | -14.0 6.8 245 25 13 7.9 4.3 17000 -13.2 8.2 250 27 14 7.8 4.3 | -12.8 9.0 245 24 12 8.0 4.4 16500 -12.0 10.4 250 26 13 7.8 4.3 | -11.6 11.1 245 23 12 8.0 4.4 16000 -10.8 12.6 250 25 13 8.1 4.5 | -10.5 13.1 245 22 12 8.1 4.4 15500 -9.7 14.5 250 24 12 8.1 4.4 | -9.3 15.3 245 21 11 8.0 4.4 15000 -8.5 16.7 250 22 11 8.3 4.6 | -8.1 17.4 250 21 11 8.6 4.7 14500 -7.2 19.0 250 21 11 8.3 4.6 | -6.8 19.8 250 20 10 8.6 4.7 14000 -6.0 21.2 250 20 10 8.9 4.9 | -5.5 22.1 250 19 10 8.9 4.9 13500 -4.6 23.7 250 19 10 9.0 4.9 | -4.2 24.4 255 18 9 9.0 4.9 13000 -3.3 26.1 255 18 9 9.0 4.9 | -2.9 26.8 255 17 9 9.1 5.0 12500 -2.0 28.4 255 18 9 9.0 4.9 | -1.5 29.3 260 16 8 9.1 5.0 12000 -0.6 30.9 255 17 9 9.0 4.9 | -0.1 31.8 260 15 8 9.0 4.9 11500 0.7 33.3 255 16 8 9.0 4.9 | 1.2 34.2 265 15 8 8.8 4.8 11000 2.1 35.8 260 16 8 8.2 4.5 | 2.5 36.5 270 14 7 8.3 4.6 10500 3.2 37.8 260 15 8 6.5 3.5 | 3.7 38.7 275 14 7 6.9 3.8 10250 3.8 38.8 260 15 8 11.4 6.3 | 4.2 39.6 275 14 7 10.6 5.8 10000 4.8 40.6 265 14 7 12.4 6.8 | 5.2 41.4 280 12 6 11.3 6.2 9750 5.5 41.9 265 13 7 7.9 4.4 | 5.8 42.4 280 12 6 7.9 4.4 9500 6.1 43.0 265 13 7 9.6 5.3 | 6.4 43.5 280 12 6 8.4 4.6 9250 6.8 44.2 265 13 7 7.4 4.1 | 7.1 44.8 285 12 6 9.1 5.0 9000 7.3 45.1 270 13 6 8.3 4.6 | 7.8 46.0 290 10 5 9.9 5.4 8750 8.1 46.6 270 12 6 10.7 5.9 | 9.2 48.6 290 10 5 9.7 5.3 8500 9.6 49.3 270 12 6 9.8 5.4 | 9.9 49.8 295 10 5 9.1 5.0 8250 10.3 50.5 275 12 6 9.3 5.1 | 10.6 51.1 290 10 5 8.9 4.9 8000 11.0 51.8 275 11 6 10.2 5.6 | 11.3 52.3 290 10 5 9.9 5.4 7750 11.8 53.2 275 11 6 10.9 6.0 | 12.0 53.6 295 10 5 10.6 5.8 7500 12.6 54.7 275 11 6 9.4 5.2 | 12.8 55.0 295 9 5 9.6 5.2 7250 13.2 55.8 280 11 6 8.0 4.4 | 13.5 56.3 295 10 5 8.4 4.6 7000 13.9 57.0 280 11 6 10.2 5.6 | 14.1 57.4 295 10 5 9.6 5.3 6750 14.7 58.5 280 10 5 11.5 6.3 | 14.9 58.8 295 9 5 10.5 5.8 6500 15.6 60.1 280 10 5 10.8 5.9 | 15.7 60.3 300 9 4 10.4 5.7 6250 16.4 61.5 280 10 5 11.4 6.2 | 16.5 61.7 295 9 5 11.2 6.1 6000 17.2 63.0 285 10 5 8.2 4.5 | 17.2 63.0 295 9 5 8.3 4.6 5750 17.7 63.9 280 9 5 11.0 6.0 | 17.8 64.0 300 8 4 8.5 4.7 5500 20.3 68.5 285 9 5 74.1 40.7 | 19.5 67.1 300 7 4 50.4 27.7 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
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