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Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000 UXUS97 KGJT 181307 SRGGJT Soaring Forecast National Weather Service Grand Junction, Colorado 707 AM MDT Thursday, April 18, 2024 This forecast is for Thursday, April 18, 2024: If the trigger temperature of 63.8 F/17.7 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1212 ft/min (6.2 m/s) Maximum height of thermals.................. 18349 ft MSL (13500 ft AGL) Forecast maximum temperature................... 76.0 F/24.9 C Time of trigger temperature.................... 1130 MDT Time of overdevelopment........................ None Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 13974 ft MSL (9125 ft AGL) Thermal soaring outlook for Friday 04/19....... Excellent Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 06:31:48 / 19:54:48 MDT Total possible sunshine........... 13 hr 23 min 0 sec (803 min 0 sec) Altitude of sun at 13:13:18 MDT... 61.93 degrees Upper air data from rawinsonde observation taken on 04/18/2024 at 0600 MDT Freezing level.................. 11355 ft MSL (6506 ft AGL) Convective condensation level... 15162 ft MSL (10313 ft AGL) Lifted condensation level....... 16322 ft MSL (11473 ft AGL) Lifted index.................... -0.4 K index......................... +17.2 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 -57.3 -71.1 250 50 26 7.6 4.2 104.4 220.0 45.7 M M 45000 -52.9 -63.2 260 61 31 2.9 1.6 85.9 186.7 37.7 M M 40000 -55.1 -67.2 275 83 43 -7.5 -4.1 59.5 139.1 23.0 M M 38000 -56.9 -70.4 275 85 44 -2.1 -1.2 48.1 118.5 15.9 M M 36000 -54.2 -65.6 275 82 42 5.2 2.8 43.5 110.4 13.2 M M 34000 -51.0 -59.8 275 75 39 6.0 3.3 39.7 103.5 10.9 M M 32000 -45.7 -50.3 280 73 38 9.4 5.1 38.0 100.3 9.9 M M 30000 -40.5 -40.9 270 66 34 7.9 4.3 37.1 98.8 9.5 M M 29000 -38.2 -36.8 275 62 32 7.7 4.2 36.3 97.4 9.0 M M 28000 -36.0 -32.8 270 56 29 7.2 3.9 35.4 95.7 8.4 M M 27000 -33.9 -29.0 270 57 29 7.1 3.9 34.4 93.9 7.7 M M 26000 -31.7 -25.1 270 54 28 6.9 3.8 33.3 92.0 6.9 M M 25000 -29.6 -21.3 270 52 27 7.2 4.0 32.3 90.2 6.2 M M 24000 -27.6 -17.7 270 52 27 6.4 3.5 31.2 88.2 5.4 M M 23000 -25.4 -13.7 265 47 24 7.7 4.2 30.3 86.6 4.7 M M 22000 -23.1 -9.6 270 47 24 7.8 4.3 29.6 85.2 4.1 M M 21000 -20.9 -5.6 270 47 24 7.1 3.9 28.7 83.6 3.4 M M 20000 -19.1 -2.4 275 48 25 6.2 3.4 27.5 81.4 2.4 M M 19500 -18.3 -0.9 275 48 25 4.2 2.3 26.6 79.9 1.7 M M 19000 -17.7 0.1 265 42 22 4.7 2.6 25.7 78.2 0.9 M M 18500 -16.8 1.8 265 42 21 6.5 3.6 25.1 77.1 0.4 M M 18000 -15.6 3.9 280 38 20 5.7 3.1 24.0 75.2 -0.6 1175 6.0 17500 -14.8 5.4 275 38 20 6.8 3.7 23.3 73.9 -1.3 1136 5.8 17000 -13.5 7.7 275 38 19 8.4 4.6 23.0 73.4 -1.5 1085 5.5 16500 -12.3 9.9 275 35 18 8.4 4.6 22.8 73.0 -1.8 1033 5.2 16000 -11.0 12.2 270 37 19 8.4 4.6 22.6 72.6 -2.0 981 5.0 15500 -9.8 14.4 270 38 19 8.4 4.6 22.3 72.2 -2.2 928 4.7 15000 -8.6 16.5 270 39 20 8.0 4.4 22.1 71.8 -2.5 878 4.5 14500 -7.4 18.7 275 40 21 8.0 4.4 21.8 71.3 -2.7 827 4.2 14000 -6.2 20.8 265 38 20 8.0 4.4 21.6 70.8 -3.0 777 3.9 13500 -5.1 22.8 265 36 19 8.0 4.4 21.3 70.3 -3.3 727 3.7 13000 -3.9 25.0 260 34 17 8.0 4.4 21.0 69.8 -3.6 677 3.4 12500 -2.7 27.1 265 27 14 8.0 4.4 20.7 69.3 -3.9 626 3.2 12000 -1.5 29.3 255 19 10 8.0 4.4 20.4 68.7 -4.2 576 2.9 11500 -0.3 31.5 250 18 9 8.0 4.4 20.1 68.2 -4.5 526 2.7 11000 0.9 33.6 245 17 9 8.0 4.4 19.8 67.7 -4.8 476 2.4 10500 2.0 35.6 240 18 9 8.0 4.4 19.5 67.1 -5.1 425 2.2 10250 2.6 36.7 235 18 9 7.9 4.3 19.3 66.8 -5.3 400 2.0 10000 3.2 37.8 235 18 9 7.4 4.1 19.2 66.5 -5.5 376 1.9 9750 3.7 38.7 240 11 6 7.2 3.9 19.0 66.2 -5.7 353 1.8 9500 4.3 39.7 235 8 4 7.2 4.0 18.8 65.8 -5.9 329 1.7 9250 4.8 40.6 245 6 3 7.2 4.0 18.6 65.5 -6.1 306 1.6 9000 5.3 41.5 260 4 2 7.2 4.0 18.4 65.1 -6.3 283 1.4 8750 5.9 42.6 265 4 2 7.2 4.0 18.2 64.7 -6.5 259 1.3 8500 6.4 43.5 280 5 3 7.2 4.0 18.0 64.4 -6.8 236 1.2 8250 6.9 44.4 290 6 3 7.2 4.0 17.8 64.0 -7.0 212 1.1 8000 7.5 45.5 295 8 4 7.2 4.0 17.6 63.7 -7.2 189 1.0 7750 8.0 46.4 290 7 4 7.2 4.0 17.4 63.3 -7.4 166 0.8 7500 8.5 47.3 275 7 4 7.2 3.9 17.2 63.0 -7.6 142 0.7 7250 9.1 48.4 275 7 3 7.2 3.9 17.0 62.6 -7.8 119 0.6 7000 9.6 49.3 280 6 3 7.2 3.9 16.8 62.3 -8.1 96 0.5 6750 10.1 50.2 285 6 3 7.2 3.9 16.6 61.9 -8.3 72 0.4 6500 10.7 51.3 300 6 3 7.2 4.0 16.4 61.6 -8.5 49 0.2 6250 11.2 52.2 310 7 4 7.1 3.9 16.2 61.2 -8.7 26 0.1 6000 11.6 52.9 280 11 5 4.5 2.5 16.0 60.7 -9.0 5 0.0 5750 11.9 53.4 280 11 6 2.0 1.1 15.4 59.8 -9.6 M M 5500 11.9 53.4 285 11 6 -2.8 -1.5 14.7 58.5 -10.3 M M 5250 11.5 52.7 295 8 4 -3.2 -1.7 13.7 56.6 -11.4 M M 5000 11.7 53.1 285 5 3 6.7 3.7 13.0 55.5 -12.0 M M * * * * * * Numerical weather prediction model forecast data valid * * * * * * 04/18/2024 at 0900 MDT | 04/18/2024 at 1200 MDT | CAPE... 0.0 LI... +2.2 | CAPE... +0.5 LI... +2.5 CINH... -0.9 K Index... +19.2 | CINH... -0.9 K Index... +17.0 | 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 -57.5 -71.5 265 53 27 4.1 2.3 | -57.5 -71.5 260 56 29 3.4 1.9 45000 -51.8 -61.2 265 62 32 -3.8 -2.1 | -52.8 -63.0 260 67 34 -2.8 -1.5 40000 -57.2 -71.0 270 77 40 -3.4 -1.9 | -56.7 -70.1 275 80 41 -2.4 -1.3 38000 -56.0 -68.8 270 78 40 4.8 2.7 | -55.5 -67.9 275 81 42 4.2 2.3 36000 -53.0 -63.4 270 76 39 4.8 2.7 | -53.0 -63.4 275 79 41 4.2 2.3 34000 -49.8 -57.6 270 73 38 6.9 3.8 | -49.9 -57.8 275 76 39 6.9 3.8 32000 -45.6 -50.1 270 68 35 7.0 3.8 | -45.7 -50.3 275 73 37 7.0 3.8 30000 -41.2 -42.2 270 64 33 7.9 4.4 | -41.4 -42.5 275 69 36 7.9 4.4 29000 -38.9 -38.0 270 62 32 8.0 4.4 | -39.0 -38.2 270 68 35 7.9 4.4 28000 -36.5 -33.7 270 61 31 8.0 4.4 | -36.6 -33.9 270 67 34 8.0 4.4 27000 -34.1 -29.4 270 60 31 7.4 4.1 | -34.3 -29.7 270 65 34 7.3 4.0 26000 -31.5 -24.7 270 57 29 7.1 3.9 | -31.7 -25.1 270 62 32 6.9 3.8 25000 -29.3 -20.7 270 55 28 7.1 3.9 | -29.6 -21.3 270 59 30 6.9 3.8 24000 -27.2 -17.0 270 53 27 6.8 3.7 | -27.5 -17.5 270 56 29 7.0 3.8 23000 -25.2 -13.4 270 51 26 6.8 3.7 | -25.5 -13.9 270 54 28 7.0 3.8 22000 -23.2 -9.8 270 49 25 6.8 3.7 | -23.4 -10.1 270 52 27 7.0 3.8 21000 -21.2 -6.2 270 48 25 6.1 3.4 | -21.3 -6.3 270 50 26 6.7 3.7 20000 -19.4 -2.9 275 47 24 6.2 3.4 | -19.3 -2.7 270 49 25 6.8 3.7 19500 -18.5 -1.3 275 47 24 6.2 3.4 | -18.3 -0.9 270 48 25 6.8 3.7 19000 -17.5 0.5 275 46 24 6.2 3.4 | -17.3 0.9 270 47 24 6.8 3.7 18500 -16.6 2.1 275 46 23 6.1 3.3 | -16.3 2.7 270 47 24 6.4 3.5 18000 -15.7 3.7 275 45 23 6.1 3.3 | -15.4 4.3 265 46 24 6.4 3.5 17500 -14.8 5.4 270 44 23 6.1 3.4 | -14.4 6.1 265 45 23 6.6 3.6 17000 -13.9 7.0 270 43 22 6.2 3.4 | -13.4 7.9 265 45 23 6.8 3.7 16500 -13.0 8.6 270 42 21 6.2 3.4 | -12.4 9.7 265 44 23 6.8 3.7 16000 -12.1 10.2 270 41 21 6.7 3.7 | -11.4 11.5 265 43 22 6.4 3.5 15500 -11.1 12.0 270 39 20 6.6 3.6 | -10.5 13.1 265 43 22 6.4 3.5 15000 -10.1 13.8 265 38 20 7.5 4.1 | -9.6 14.7 265 42 21 6.4 3.5 14500 -9.0 15.8 265 37 19 7.6 4.2 | -8.7 16.3 265 40 21 6.4 3.5 14000 -7.9 17.8 265 35 18 7.7 4.2 | -7.7 18.1 265 38 20 7.3 4.0 13500 -6.7 19.9 260 34 17 7.7 4.2 | -6.6 20.1 260 36 18 7.7 4.2 13000 -5.6 21.9 260 32 16 7.6 4.2 | -5.4 22.3 260 33 17 7.5 4.1 12500 -4.5 23.9 260 30 15 7.4 4.1 | -4.4 24.1 260 30 16 7.2 4.0 12000 -3.4 25.9 260 28 14 7.4 4.0 | -3.3 26.1 260 27 14 7.3 4.0 11500 -2.3 27.9 260 25 13 7.2 4.0 | -2.2 28.0 260 25 13 7.3 4.0 11000 -1.2 29.8 260 23 12 6.8 3.7 | -1.1 30.0 260 22 11 6.8 3.8 10500 -0.2 31.6 260 21 11 5.8 3.2 | -0.2 31.6 260 20 11 5.5 3.0 10250 0.2 32.4 260 20 10 8.7 4.8 | 0.3 32.5 260 20 10 9.7 5.3 10000 1.0 33.8 260 18 9 9.0 4.9 | 1.2 34.2 260 18 9 11.1 6.1 9750 1.5 34.7 260 17 9 6.3 3.5 | 1.9 35.4 260 18 9 7.7 4.2 9500 2.0 35.6 260 16 8 7.1 3.9 | 2.5 36.5 260 17 9 9.0 5.0 9250 2.5 36.5 265 15 8 6.7 3.7 | 3.1 37.6 260 16 8 7.1 3.9 9000 3.0 37.4 265 14 7 6.6 3.6 | 4.2 39.6 265 14 7 8.8 4.8 8750 4.0 39.2 265 11 6 7.2 3.9 | 4.9 40.8 265 13 7 9.7 5.3 8500 4.6 40.3 270 10 5 6.1 3.3 | 5.6 42.1 270 12 6 8.1 4.4 8250 4.9 40.8 270 9 4 4.6 2.5 | 6.1 43.0 270 11 6 6.7 3.7 8000 5.3 41.5 275 7 4 6.2 3.4 | 6.7 44.1 275 11 6 9.4 5.1 7750 5.8 42.4 275 6 3 7.7 4.2 | 7.5 45.5 275 10 5 11.4 6.3 7500 6.4 43.5 280 5 3 5.7 3.2 | 8.3 46.9 275 10 5 8.9 4.9 7250 6.7 44.1 285 4 2 3.9 2.1 | 8.8 47.8 275 10 5 6.8 3.7 7000 7.0 44.6 290 4 2 6.6 3.6 | 9.4 48.9 280 10 5 11.1 6.1 6750 7.6 45.7 310 3 2 8.3 4.5 | 10.4 50.7 275 9 5 12.9 7.1 6500 8.2 46.8 325 3 1 7.5 4.1 | 11.3 52.3 280 8 4 10.3 5.7 6250 8.8 47.8 345 2 1 7.2 4.0 | 12.0 53.6 280 8 4 9.9 5.5 6000 9.3 48.7 360 3 1 8.5 4.6 | 12.8 55.0 285 8 4 9.9 5.4 5750 10.1 50.2 350 3 1 14.6 8.0 | 13.7 56.7 280 7 4 17.8 9.8 5500 11.6 52.9 005 3 1 24.1 13.2 | 16.3 61.3 290 7 4 61.2 33.6 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 04/18/2024 at 1500 MDT | 04/18/2024 at 1800 MDT | CAPE... +1.2 LI... +2.3 | CAPE... 0.0 LI... +1.2 CINH... 0.0 K Index... +14.1 | CINH... -0.6 K Index... +15.2 | 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 -57.8 -72.0 260 56 29 2.4 1.3 | -57.7 -71.9 265 55 28 2.0 1.1 45000 -54.5 -66.1 265 70 36 -2.7 -1.5 | -55.0 -67.0 270 72 37 -2.8 -1.5 40000 -58.2 -72.8 270 86 44 -2.2 -1.2 | -59.1 -74.4 260 84 43 -2.4 -1.3 38000 -56.4 -69.5 270 83 43 5.3 2.9 | -56.8 -70.2 260 85 44 6.3 3.5 36000 -53.2 -63.8 270 77 40 5.3 2.9 | -53.0 -63.4 260 84 43 6.3 3.5 34000 -49.5 -57.1 270 72 37 7.9 4.3 | -49.0 -56.2 260 81 41 7.6 4.2 32000 -44.8 -48.6 270 71 36 7.9 4.3 | -44.4 -47.9 265 71 37 7.6 4.2 30000 -40.1 -40.2 275 69 36 7.6 4.2 | -39.8 -39.6 265 64 33 7.9 4.3 29000 -37.8 -36.0 275 69 35 7.6 4.2 | -37.4 -35.3 270 63 32 7.9 4.3 28000 -35.6 -32.1 275 68 35 7.6 4.2 | -35.1 -31.2 270 61 32 7.9 4.3 27000 -33.3 -27.9 270 68 35 6.9 3.8 | -32.7 -26.9 270 60 31 7.0 3.8 26000 -30.8 -23.4 270 65 33 6.7 3.7 | -30.2 -22.4 270 60 31 6.8 3.8 25000 -28.8 -19.8 270 63 32 6.8 3.7 | -28.1 -18.6 270 60 31 6.9 3.8 24000 -26.8 -16.2 270 61 31 6.6 3.6 | -26.2 -15.2 270 59 30 6.0 3.3 23000 -24.8 -12.6 265 58 30 6.6 3.6 | -24.4 -11.9 265 57 30 6.0 3.3 22000 -22.8 -9.0 265 56 29 6.7 3.7 | -22.6 -8.7 265 56 29 6.0 3.3 21000 -20.8 -5.4 265 54 28 7.0 3.8 | -20.8 -5.4 265 54 28 6.2 3.4 20000 -18.7 -1.7 265 52 27 7.0 3.8 | -18.9 -2.0 265 51 26 6.2 3.4 19500 -17.7 0.1 265 52 27 7.0 3.8 | -18.0 -0.4 265 50 26 6.2 3.4 19000 -16.6 2.1 265 51 26 7.0 3.8 | -17.1 1.2 265 48 25 6.0 3.3 18500 -15.6 3.9 265 50 26 6.9 3.8 | -16.1 3.0 265 47 24 7.4 4.1 18000 -14.5 5.9 265 49 25 6.9 3.8 | -15.0 5.0 265 46 24 7.3 4.0 17500 -13.5 7.7 265 48 25 6.7 3.7 | -14.0 6.8 260 44 23 7.5 4.1 17000 -12.5 9.5 265 47 24 6.4 3.5 | -12.8 9.0 260 43 22 7.6 4.2 16500 -11.6 11.1 265 45 23 6.4 3.5 | -11.7 10.9 260 41 21 7.7 4.2 16000 -10.7 12.7 265 42 22 6.2 3.4 | -10.5 13.1 260 40 20 8.1 4.4 15500 -9.8 14.4 265 40 21 6.2 3.4 | -9.3 15.3 260 38 19 8.0 4.4 15000 -8.8 16.2 265 38 19 7.4 4.0 | -8.1 17.4 260 36 19 8.3 4.5 14500 -7.7 18.1 265 36 18 7.4 4.1 | -6.9 19.6 260 34 18 8.2 4.5 14000 -6.6 20.1 260 34 17 7.7 4.2 | -5.7 21.7 260 32 17 8.3 4.5 13500 -5.5 22.1 260 32 16 7.8 4.3 | -4.4 24.1 260 31 16 8.3 4.6 13000 -4.3 24.3 260 30 15 8.1 4.5 | -3.2 26.2 260 29 15 8.5 4.7 12500 -3.1 26.4 260 28 15 8.3 4.6 | -1.9 28.6 260 28 14 8.6 4.7 12000 -1.9 28.6 260 27 14 8.5 4.7 | -0.7 30.7 260 26 14 8.9 4.9 11500 -0.6 30.9 260 25 13 8.6 4.7 | 0.7 33.3 260 25 13 9.1 5.0 11000 0.7 33.3 260 24 12 7.8 4.3 | 2.1 35.8 260 24 13 8.3 4.6 10500 1.8 35.2 260 22 11 6.0 3.3 | 3.2 37.8 260 24 12 6.7 3.7 10250 2.3 36.1 260 22 11 10.9 6.0 | 3.8 38.8 260 24 12 11.1 6.1 10000 3.3 37.9 260 21 11 12.1 6.6 | 4.8 40.6 260 23 12 12.0 6.6 9750 4.0 39.2 260 20 10 7.7 4.2 | 5.4 41.7 260 22 12 8.0 4.4 9500 4.6 40.3 260 19 10 9.3 5.1 | 6.1 43.0 260 22 11 9.6 5.3 9250 5.3 41.5 265 18 9 7.3 4.0 | 6.8 44.2 260 21 11 7.2 4.0 9000 5.8 42.4 265 17 9 8.3 4.6 | 7.3 45.1 260 21 11 7.8 4.3 8750 7.3 45.1 265 16 8 10.5 5.8 | 8.7 47.7 265 19 10 9.8 5.4 8500 8.1 46.6 265 16 8 9.7 5.3 | 9.4 48.9 265 18 9 8.9 4.9 8250 8.8 47.8 265 16 8 8.9 4.9 | 10.0 50.0 265 18 9 8.1 4.4 8000 9.5 49.1 270 16 8 10.3 5.6 | 10.7 51.3 265 17 9 9.7 5.3 7750 10.3 50.5 270 15 8 11.5 6.3 | 11.5 52.7 265 17 9 10.9 6.0 7500 11.1 52.0 265 14 7 9.2 5.0 | 12.3 54.1 265 16 8 9.3 5.1 7250 11.7 53.1 270 15 8 7.1 3.9 | 12.9 55.2 265 17 9 7.8 4.3 7000 12.3 54.1 270 15 8 10.9 6.0 | 13.5 56.3 265 17 9 10.0 5.5 6750 13.3 55.9 270 14 7 12.6 6.9 | 14.4 57.9 265 16 8 11.3 6.2 6500 14.1 57.4 270 13 7 10.5 5.8 | 15.2 59.4 265 15 8 10.3 5.7 6250 14.9 58.8 270 13 7 10.7 5.9 | 15.9 60.6 265 15 8 10.6 5.8 6000 15.7 60.3 270 13 7 8.4 4.6 | 16.7 62.1 265 15 8 8.5 4.7 5750 16.4 61.5 270 12 6 14.1 7.8 | 17.3 63.1 265 13 7 9.8 5.4 5500 19.4 66.9 275 11 6 84.1 46.1 | 19.1 66.4 265 12 6 50.0 27.4 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
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