Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
426 UXUS97 KGJT 261307 SRGGJT Soaring Forecast National Weather Service Grand Junction, Colorado 707 AM MDT Sunday, May 26, 2024 This forecast is for Sunday, May 26, 2024: If the trigger temperature of 59.2 F/15.1 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 898 ft/min (4.6 m/s) Maximum height of thermals.................. 16293 ft MSL (11454 ft AGL) Forecast maximum temperature................... 76.0 F/24.9 C Time of trigger temperature.................... 0945 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................. 14960 ft MSL (10121 ft AGL) Thermal soaring outlook for Monday 05/27....... Excellent Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 05:52:26 / 20:30:08 MDT Total possible sunshine........... 14 hr 37 min 42 sec (877 min 42 sec) Altitude of sun at 13:11:17 MDT... 72.03 degrees Upper air data from rawinsonde observation taken on 05/26/2024 at 0600 MDT Freezing level.................. 10008 ft MSL (5169 ft AGL) Convective condensation level... 11696 ft MSL (6857 ft AGL) Lifted condensation level....... 14434 ft MSL (9595 ft AGL) Lifted index.................... -2.5 K index......................... +16.7 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 -55.1 -67.2 255 48 25 0.3 0.2 107.7 225.9 47.7 M M 45000 -50.3 -58.5 255 55 28 0.6 0.3 90.0 193.9 40.2 M M 40000 -52.7 -62.9 270 57 30 -0.9 -0.5 63.0 145.4 25.3 M M 38000 -52.3 -62.1 280 72 37 -1.1 -0.6 54.7 130.5 20.4 M M 36000 -50.9 -59.6 270 61 31 4.7 2.6 48.2 118.8 16.5 M M 34000 -48.0 -54.4 275 63 32 3.7 2.1 44.0 111.3 13.9 M M 32000 -46.3 -51.3 280 60 31 4.6 2.5 37.3 99.1 9.4 M M 30000 -41.3 -42.3 280 55 28 7.4 4.1 36.1 97.0 8.8 M M 29000 -39.0 -38.2 280 55 28 6.9 3.8 35.4 95.7 8.3 M M 28000 -36.9 -34.4 280 52 27 7.8 4.3 34.2 93.6 7.5 M M 27000 -34.2 -29.6 275 47 24 9.1 5.0 34.0 93.1 7.4 M M 26000 -31.7 -25.1 285 44 23 7.8 4.3 33.4 92.1 7.0 M M 25000 -29.4 -20.9 290 42 22 7.0 3.8 32.7 90.9 6.6 M M 24000 -27.1 -16.8 290 42 22 9.6 5.2 31.9 89.5 6.0 M M 23000 -25.0 -13.0 285 40 21 6.8 3.7 30.9 87.7 5.2 M M 22000 -22.9 -9.2 295 39 20 7.6 4.2 30.0 85.9 4.5 M M 21000 -20.2 -4.4 290 39 20 9.0 4.9 29.6 85.3 4.3 M M 20000 -18.0 -0.4 280 37 19 6.2 3.4 28.8 83.8 3.6 M M 19500 -17.1 1.2 290 32 17 6.1 3.4 28.1 82.7 3.1 M M 19000 -16.2 2.8 300 29 15 6.0 3.3 27.5 81.5 2.5 M M 18500 -15.3 4.5 295 31 16 6.8 3.7 26.9 80.4 2.0 M M 18000 -14.2 6.4 290 28 14 7.2 3.9 26.4 79.6 1.6 M M 17500 -13.1 8.4 285 30 15 7.2 4.0 26.0 78.8 1.3 M M 17000 -11.4 11.5 280 31 16 7.6 4.2 25.4 77.6 0.8 M M 16500 -10.6 12.9 280 35 18 4.2 2.3 24.7 76.5 0.2 M M 16000 -9.9 14.2 290 41 21 4.7 2.6 23.8 74.9 -0.6 870 4.4 15500 -9.3 15.3 290 44 23 3.7 2.0 23.0 73.4 -1.5 836 4.2 15000 -9.5 14.9 295 38 19 -3.9 -2.1 21.2 70.2 -3.2 828 4.2 14500 -9.6 14.7 300 32 16 5.9 3.2 19.5 67.2 -4.8 817 4.1 14000 -8.4 16.9 310 27 14 8.1 4.5 19.3 66.8 -5.0 765 3.9 13500 -7.2 19.0 310 25 13 8.3 4.6 19.1 66.4 -5.3 713 3.6 13000 -5.9 21.4 315 24 12 8.3 4.6 18.9 66.0 -5.5 662 3.4 12500 -4.7 23.5 315 22 11 8.3 4.6 18.6 65.6 -5.8 610 3.1 12000 -3.5 25.7 310 15 8 8.4 4.6 18.4 65.1 -6.0 558 2.8 11500 -2.2 28.0 305 14 7 8.8 4.8 18.1 64.7 -6.3 506 2.6 11000 -1.3 29.7 295 13 7 3.5 1.9 17.6 63.7 -6.9 464 2.4 10500 -0.8 30.6 285 12 6 3.8 2.1 16.6 61.9 -7.9 435 2.2 10250 -0.5 31.1 275 12 6 5.6 3.1 16.2 61.2 -8.3 418 2.1 10000 0.0 32.0 270 11 6 8.4 4.6 16.0 60.8 -8.6 395 2.0 9750 0.7 33.3 265 12 6 9.4 5.2 16.0 60.7 -8.6 368 1.9 9500 1.4 34.5 260 11 6 9.2 5.0 15.9 60.6 -8.7 340 1.7 9250 2.0 35.6 255 8 4 9.2 5.1 15.9 60.6 -8.8 313 1.6 9000 2.7 36.9 250 5 3 9.3 5.1 15.8 60.5 -8.9 285 1.4 8750 3.4 38.1 255 6 3 9.0 4.9 15.8 60.4 -9.0 258 1.3 8500 3.9 39.0 260 7 4 7.0 3.8 15.7 60.2 -9.1 233 1.2 8250 4.4 39.9 245 7 3 6.4 3.5 15.4 59.7 -9.5 213 1.1 8000 4.9 40.8 225 7 4 8.1 4.4 15.2 59.4 -9.7 190 1.0 7750 5.5 41.9 225 8 4 8.4 4.6 15.1 59.2 -9.9 164 0.8 7500 6.1 43.0 210 9 5 8.8 4.9 15.0 59.0 -10.0 138 0.7 7250 6.7 44.1 185 6 3 6.8 3.8 14.9 58.8 -10.1 112 0.6 7000 7.1 44.8 160 10 5 4.5 2.5 14.5 58.2 -10.5 94 0.5 6750 7.4 45.3 160 12 6 4.9 2.7 14.2 57.5 -11.0 77 0.4 6500 7.8 46.0 155 14 7 4.7 2.6 13.8 56.8 -11.4 59 0.3 6250 8.1 46.6 155 16 8 5.0 2.7 13.4 56.1 -11.8 42 0.2 6000 8.4 47.1 160 15 8 3.7 2.0 13.0 55.4 -12.2 25 0.1 5750 8.7 47.7 155 13 7 4.1 2.2 12.5 54.5 -12.8 11 0.1 5500 9.1 48.4 150 10 5 6.7 3.7 12.2 54.0 -13.1 M M 5250 9.2 48.6 150 7 4 -5.2 -2.9 11.7 53.1 -13.7 M M 5000 8.0 46.4 140 5 2 -25.5 -14.0 9.7 49.5 -15.7 7 0.0 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 05/26/2024 at 0900 MDT | 05/26/2024 at 1200 MDT | CAPE... +1.5 LI... +3.2 | CAPE... +0.9 LI... +2.6 CINH... -4.6 K Index... +11.5 | CINH... -0.6 K Index... +9.9 | 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 -54.6 -66.3 260 45 23 1.5 0.8 | -55.5 -67.9 260 47 24 0.5 0.3 45000 -52.7 -62.9 265 51 26 -1.6 -0.9 | -55.0 -67.0 265 55 29 -1.7 -0.9 40000 -55.0 -67.0 280 62 32 -1.3 -0.7 | -57.5 -71.5 280 52 27 -1.7 -0.9 38000 -53.7 -64.7 290 58 30 3.3 1.8 | -55.3 -67.5 290 47 24 5.0 2.8 36000 -51.8 -61.2 305 52 27 3.3 1.8 | -52.3 -62.1 305 44 23 5.0 2.8 34000 -48.9 -56.0 315 51 26 7.4 4.1 | -48.6 -55.5 315 43 22 7.9 4.3 32000 -44.5 -48.1 320 51 26 7.4 4.1 | -43.9 -47.0 310 44 23 7.8 4.3 30000 -40.1 -40.2 315 51 26 7.0 3.8 | -39.0 -38.2 310 44 23 8.5 4.7 29000 -38.0 -36.4 315 50 26 7.0 3.8 | -36.4 -33.5 305 44 23 8.5 4.7 28000 -36.0 -32.8 310 49 25 7.0 3.8 | -33.9 -29.0 305 44 23 8.5 4.7 27000 -33.9 -29.0 305 48 25 7.0 3.9 | -31.4 -24.5 305 44 23 7.6 4.2 26000 -31.7 -25.1 300 47 24 7.1 3.9 | -28.5 -19.3 305 44 22 7.7 4.2 25000 -29.1 -20.4 300 45 23 7.1 3.9 | -26.1 -15.0 305 43 22 7.7 4.2 24000 -26.9 -16.4 295 44 23 7.7 4.2 | -24.0 -11.2 300 42 22 5.4 2.9 23000 -24.6 -12.3 295 43 22 7.7 4.2 | -22.4 -8.3 300 41 21 5.6 3.1 22000 -22.3 -8.1 295 41 21 7.7 4.2 | -20.7 -5.3 295 39 20 5.6 3.1 21000 -20.1 -4.2 295 40 21 6.9 3.8 | -19.0 -2.2 295 38 19 6.1 3.4 20000 -18.0 -0.4 295 40 20 7.0 3.8 | -17.2 1.0 295 36 19 6.1 3.4 19500 -17.0 1.4 295 39 20 7.0 3.8 | -16.2 2.8 295 35 18 6.1 3.4 19000 -16.0 3.2 295 39 20 7.0 3.8 | -15.3 4.5 295 34 18 6.1 3.4 18500 -14.9 5.2 295 38 20 6.8 3.8 | -14.4 6.1 295 33 17 6.3 3.4 18000 -13.9 7.0 295 38 19 6.8 3.7 | -13.5 7.7 295 32 17 6.3 3.5 17500 -12.9 8.8 295 37 19 6.1 3.4 | -12.6 9.3 295 32 16 6.1 3.3 17000 -12.1 10.2 295 36 19 5.5 3.0 | -11.7 10.9 295 31 16 6.0 3.3 16500 -11.3 11.7 295 35 18 5.4 3.0 | -10.8 12.6 295 30 15 5.9 3.2 16000 -10.6 12.9 295 34 17 4.5 2.5 | -10.0 14.0 295 29 15 5.5 3.0 15500 -9.9 14.2 295 32 16 4.5 2.5 | -9.2 15.4 295 27 14 5.7 3.1 15000 -9.2 15.4 295 30 16 5.1 2.8 | -8.4 16.9 295 26 13 4.5 2.5 14500 -8.5 16.7 295 28 15 5.1 2.8 | -7.8 18.0 295 24 12 4.6 2.5 14000 -7.7 18.1 300 27 14 5.5 3.0 | -7.0 19.4 295 23 12 6.1 3.3 13500 -6.9 19.6 300 25 13 5.7 3.1 | -6.1 21.0 295 21 11 6.2 3.4 13000 -6.1 21.0 300 23 12 6.2 3.4 | -5.2 22.6 295 20 10 7.2 4.0 12500 -5.1 22.8 300 21 11 6.6 3.6 | -4.1 24.6 290 19 10 7.6 4.1 12000 -4.2 24.4 300 19 10 7.1 3.9 | -3.0 26.6 290 17 9 8.0 4.4 11500 -3.0 26.6 300 17 9 7.5 4.1 | -1.8 28.8 290 16 8 8.2 4.5 11000 -1.9 28.6 295 15 8 7.3 4.0 | -0.6 30.9 290 14 7 7.5 4.1 10500 -0.9 30.4 295 14 7 6.7 3.7 | 0.5 32.9 285 13 7 6.5 3.6 10250 -0.4 31.3 295 13 7 8.3 4.6 | 1.0 33.8 285 12 6 9.7 5.3 10000 0.3 32.5 290 11 6 8.5 4.7 | 1.8 35.2 285 12 6 10.5 5.8 9750 0.8 33.4 290 10 5 7.0 3.8 | 2.5 36.5 285 11 6 8.0 4.4 9500 1.3 34.3 285 10 5 7.5 4.1 | 3.1 37.6 280 10 5 8.9 4.9 9250 1.9 35.4 285 9 4 7.0 3.9 | 3.7 38.7 280 10 5 7.8 4.3 9000 2.4 36.3 280 8 4 6.5 3.6 | 4.3 39.7 280 9 5 8.1 4.4 8750 2.8 37.0 280 7 4 6.8 3.7 | 4.9 40.8 280 8 4 9.2 5.0 8500 3.8 38.8 265 5 3 6.2 3.4 | 6.3 43.3 275 7 4 7.8 4.3 8250 4.2 39.6 260 5 2 5.2 2.9 | 6.8 44.2 280 7 4 7.1 3.9 8000 4.7 40.5 255 4 2 7.5 4.1 | 7.4 45.3 280 7 3 11.0 6.1 7750 5.3 41.5 245 3 2 8.9 4.9 | 8.3 46.9 280 6 3 12.1 6.6 7500 5.8 42.4 230 3 1 6.2 3.4 | 9.1 48.4 280 6 3 8.3 4.6 7250 6.1 43.0 215 3 1 3.6 2.0 | 9.6 49.3 285 6 3 6.0 3.3 7000 6.5 43.7 205 3 1 9.7 5.3 | 10.2 50.4 285 6 3 12.1 6.7 6750 7.5 45.5 195 3 1 12.2 6.7 | 11.3 52.3 285 5 3 13.6 7.4 6500 8.2 46.8 185 2 1 8.7 4.8 | 12.1 53.8 285 5 3 9.8 5.4 6250 8.8 47.8 180 2 1 8.1 4.4 | 12.9 55.2 290 5 3 9.2 5.1 6000 9.4 48.9 170 2 1 10.5 5.8 | 13.6 56.5 290 5 2 12.4 6.8 5750 10.5 50.9 175 2 1 18.3 10.0 | 14.9 58.8 285 4 2 24.9 13.7 5500 11.9 53.4 165 2 1 18.4 10.1 | 17.2 63.0 295 4 2 34.8 19.1 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 05/26/2024 at 1500 MDT | 05/26/2024 at 1800 MDT | CAPE... +6.9 LI... +2.4 | CAPE... +0.4 LI... +2.0 CINH... -2.2 K Index... +15.0 | CINH... -3.5 K Index... +19.5 | 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 -56.4 -69.5 260 50 26 -0.2 -0.1 | -56.8 -70.2 265 48 25 0.3 0.2 45000 -57.0 -70.6 270 56 29 -1.3 -0.7 | -56.7 -70.1 275 50 26 -1.4 -0.8 40000 -58.9 -74.0 275 48 25 -1.8 -1.0 | -58.9 -74.0 275 47 24 -1.7 -1.0 38000 -56.0 -68.8 280 43 22 6.0 3.3 | -56.2 -69.2 275 43 22 5.9 3.2 36000 -52.4 -62.3 285 38 20 6.0 3.3 | -52.7 -62.9 275 40 21 5.9 3.2 34000 -48.1 -54.6 290 36 19 8.4 4.6 | -47.8 -54.0 275 37 19 8.6 4.7 32000 -43.1 -45.6 290 38 20 8.4 4.6 | -42.6 -44.7 280 37 19 8.6 4.7 30000 -38.2 -36.8 290 39 20 8.0 4.4 | -37.6 -35.7 285 36 19 8.1 4.5 29000 -35.8 -32.4 290 40 20 8.0 4.4 | -35.2 -31.4 285 36 18 8.1 4.5 28000 -33.4 -28.1 285 40 20 8.0 4.4 | -32.7 -26.9 285 36 18 8.1 4.4 27000 -30.4 -22.7 285 39 20 8.1 4.4 | -30.4 -22.7 285 35 18 7.6 4.2 26000 -27.9 -18.2 290 37 19 8.1 4.4 | -28.1 -18.6 285 33 17 7.6 4.2 25000 -25.5 -13.9 290 36 18 8.0 4.4 | -25.8 -14.4 285 32 16 7.6 4.2 24000 -23.3 -9.9 290 35 18 6.2 3.4 | -23.6 -10.5 285 31 16 6.8 3.8 23000 -21.4 -6.5 290 34 18 6.2 3.4 | -21.6 -6.9 290 30 15 6.9 3.8 22000 -19.6 -3.3 290 34 17 6.2 3.4 | -19.5 -3.1 290 29 15 6.9 3.8 21000 -17.7 0.1 290 33 17 6.1 3.3 | -17.1 1.2 290 29 15 6.1 3.3 20000 -15.9 3.4 290 32 16 6.1 3.3 | -15.3 4.5 290 28 14 6.1 3.3 19500 -15.0 5.0 290 31 16 6.1 3.3 | -14.4 6.1 290 27 14 6.0 3.3 19000 -14.1 6.6 290 30 16 6.0 3.3 | -13.5 7.7 290 27 14 5.5 3.0 18500 -13.2 8.2 290 29 15 5.8 3.2 | -12.8 9.0 290 26 13 5.0 2.7 18000 -12.4 9.7 290 28 15 5.9 3.2 | -12.1 10.2 290 25 13 4.9 2.7 17500 -11.5 11.3 290 27 14 5.6 3.1 | -11.3 11.7 290 24 13 5.5 3.0 17000 -10.7 12.7 290 26 13 5.6 3.1 | -10.6 12.9 290 23 12 5.5 3.0 16500 -9.9 14.2 290 25 13 5.5 3.0 | -9.8 14.4 290 22 12 6.5 3.5 16000 -9.2 15.4 290 23 12 5.5 3.0 | -8.8 16.2 290 21 11 7.0 3.9 15500 -8.4 16.9 295 22 12 5.5 3.0 | -7.8 18.0 285 20 10 7.3 4.0 15000 -7.5 18.5 295 21 11 6.7 3.7 | -6.6 20.1 285 18 9 7.9 4.3 14500 -6.5 20.3 295 20 11 6.5 3.6 | -5.5 22.1 280 17 9 7.8 4.3 14000 -5.5 22.1 300 19 10 7.8 4.3 | -4.3 24.3 280 15 8 8.6 4.7 13500 -4.4 24.1 295 18 9 7.8 4.3 | -3.0 26.6 275 14 7 8.5 4.7 13000 -3.2 26.2 295 17 9 8.1 4.4 | -1.7 28.9 270 13 7 9.0 5.0 12500 -2.0 28.4 295 15 8 8.1 4.5 | -0.4 31.3 270 13 7 9.0 4.9 12000 -0.8 30.6 290 14 7 8.8 4.8 | 0.9 33.6 270 12 6 9.3 5.1 11500 0.5 32.9 290 13 7 9.0 4.9 | 2.3 36.1 265 12 6 9.4 5.1 11000 1.8 35.2 285 13 7 8.3 4.6 | 3.7 38.7 265 11 6 8.6 4.7 10500 3.0 37.4 285 12 6 7.6 4.2 | 4.9 40.8 265 11 6 8.0 4.4 10250 3.7 38.7 285 12 6 10.2 5.6 | 5.6 42.1 265 11 6 10.6 5.8 10000 4.5 40.1 285 11 6 10.9 6.0 | 6.5 43.7 265 10 5 11.0 6.0 9750 5.2 41.4 285 11 6 8.7 4.8 | 7.2 45.0 270 10 5 8.6 4.7 9500 5.9 42.6 280 11 6 9.5 5.2 | 7.8 46.0 270 10 5 9.4 5.2 9250 6.6 43.9 280 10 5 8.5 4.7 | 8.5 47.3 270 10 5 8.7 4.8 9000 7.2 45.0 285 10 5 8.8 4.8 | 9.1 48.4 270 9 5 8.8 4.8 8750 8.6 47.5 285 10 5 9.8 5.4 | 9.8 49.6 270 9 4 9.3 5.1 8500 9.3 48.7 285 9 5 8.5 4.7 | 10.5 50.9 270 8 4 9.5 5.2 8250 9.9 49.8 285 9 5 8.4 4.6 | 11.2 52.2 270 8 4 8.3 4.6 8000 10.6 51.1 285 9 5 11.0 6.0 | 11.8 53.2 275 7 4 8.4 4.6 7750 11.5 52.7 285 9 5 11.4 6.3 | 13.3 55.9 275 7 4 10.4 5.7 7500 12.3 54.1 285 9 5 8.9 4.9 | 14.0 57.2 275 7 4 8.8 4.8 7250 12.8 55.0 285 9 5 7.6 4.2 | 14.6 58.3 280 7 3 8.2 4.5 7000 13.5 56.3 285 9 4 11.6 6.4 | 15.3 59.5 280 6 3 10.9 6.0 6750 14.5 58.1 285 8 4 12.5 6.9 | 16.2 61.2 275 6 3 11.5 6.3 6500 15.3 59.5 285 8 4 10.3 5.7 | 17.0 62.6 280 6 3 10.2 5.6 6250 16.1 61.0 285 8 4 9.9 5.4 | 17.7 63.9 285 6 3 10.2 5.6 6000 16.9 62.4 285 8 4 11.4 6.3 | 18.5 65.3 285 5 3 9.8 5.4 5750 18.0 64.4 285 7 4 22.5 12.4 | 19.3 66.7 280 5 3 14.2 7.8 5500 20.6 69.1 290 7 4 51.5 28.3 | 21.1 70.0 295 5 2 38.1 20.9 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 ________________________________________________________________________________ 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