Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
101 UXUS97 KGJT 231306 SRGGJT Soaring Forecast National Weather Service Grand Junction, Colorado 706 AM MDT Monday, September 23, 2024 This forecast is for Monday, September 23, 2024: If the trigger temperature of 72.0 F/22.2 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1174 ft/min (6.0 m/s) Maximum height of thermals.................. 15958 ft MSL (11119 ft AGL) Forecast maximum temperature................... 81.0 F/27.7 C Time of trigger temperature.................... 1145 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................. 11171 ft MSL (6332 ft AGL) Thermal soaring outlook for Tuesday 09/24...... Good Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 07:03:33 / 19:08:56 MDT Total possible sunshine........... 12 hr 5 min 23 sec (725 min 23 sec) Altitude of sun at 13:06:15 MDT... 50.36 degrees Upper air data from rawinsonde observation taken on 09/23/2024 at 0600 MDT Freezing level.................. 13232 ft MSL (8393 ft AGL) Convective condensation level... 13536 ft MSL (8697 ft AGL) Lifted condensation level....... 14432 ft MSL (9592 ft AGL) Lifted index.................... -2.5 K index......................... +25.3 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 -59.4 -74.9 290 24 12 2.4 1.3 98.7 209.6 41.1 M M 45000 -55.8 -68.4 315 34 18 4.1 2.2 78.9 174.1 31.9 M M 40000 -52.4 -62.3 360 33 17 -7.3 -4.0 61.4 142.4 22.5 M M 38000 -52.2 -62.0 360 32 16 7.4 4.0 52.9 127.2 17.4 M M 36000 -49.0 -56.2 360 36 18 5.2 2.9 48.9 120.1 15.1 M M 34000 -46.4 -51.5 005 33 17 4.0 2.2 44.4 112.0 12.3 M M 32000 -43.0 -45.4 320 18 9 9.9 5.4 40.0 103.9 9.4 M M 30000 -37.5 -35.5 305 16 8 9.3 5.1 39.6 103.2 9.3 M M 29000 -34.8 -30.6 305 15 8 9.3 5.1 39.4 102.9 9.3 M M 28000 -32.1 -25.8 275 8 4 7.0 3.8 39.0 102.2 9.1 M M 27000 -30.0 -22.0 280 10 5 7.0 3.8 37.9 100.3 8.4 M M 26000 -27.8 -18.0 275 13 7 8.8 4.8 37.0 98.6 7.7 M M 25000 -25.2 -13.4 265 10 5 8.9 4.9 36.7 98.0 7.5 M M 24000 -22.9 -9.2 265 7 4 6.9 3.8 36.0 96.7 7.0 M M 23000 -20.8 -5.4 250 4 2 9.2 5.1 35.0 94.9 6.2 M M 22000 -18.1 -0.6 260 4 2 8.4 4.6 34.7 94.4 6.1 M M 21000 -15.6 3.9 220 4 2 7.9 4.4 34.2 93.5 5.8 M M 20000 -13.4 7.9 195 6 3 7.3 4.0 33.3 91.9 5.1 M M 19500 -12.3 9.9 200 5 3 7.2 3.9 32.8 91.1 4.7 M M 19000 -11.2 11.8 235 6 3 5.7 3.1 32.5 90.5 4.3 M M 18500 -10.3 13.5 225 6 3 8.5 4.7 31.8 89.3 3.8 M M 18000 -8.5 16.7 235 7 4 7.4 4.0 31.4 88.6 3.5 M M 17500 -7.4 18.7 255 10 5 7.5 4.1 31.0 87.9 3.1 M M 17000 -6.4 20.5 265 13 6 7.6 4.2 30.7 87.2 2.7 M M 16500 -5.4 22.3 275 10 5 1.2 0.7 30.1 86.1 2.2 M M 16000 -6.4 20.5 335 8 4 -6.4 -3.5 27.4 81.2 -0.3 976 5.0 15500 -5.9 21.4 330 8 4 9.6 5.2 26.3 79.4 -1.2 946 4.8 15000 -4.6 23.7 340 6 3 9.4 5.1 26.2 79.2 -1.4 891 4.5 14500 -3.3 26.1 005 9 5 8.0 4.4 26.0 78.9 -1.6 839 4.3 14000 -2.1 28.2 025 6 3 9.2 5.0 25.8 78.5 -1.8 786 4.0 13500 -0.6 30.9 030 7 3 9.7 5.3 25.8 78.5 -1.8 729 3.7 13000 0.8 33.4 015 9 4 8.8 4.8 25.8 78.5 -1.9 671 3.4 12500 1.9 35.4 355 6 3 7.9 4.3 25.5 77.9 -2.2 624 3.2 12000 3.1 37.6 330 8 4 7.8 4.3 25.2 77.4 -2.5 574 2.9 11500 4.2 39.6 330 7 4 8.5 4.7 24.9 76.8 -2.9 524 2.7 11000 5.5 41.9 330 4 2 9.2 5.0 24.8 76.7 -3.1 472 2.4 10500 6.7 44.1 360 4 2 8.4 4.6 24.6 76.4 -3.3 419 2.1 10250 7.3 45.1 355 3 2 7.3 4.0 24.5 76.1 -3.4 394 2.0 10000 7.8 46.0 340 3 2 6.8 3.7 24.3 75.7 -3.7 372 1.9 9750 8.3 46.9 305 7 4 7.2 4.0 24.1 75.3 -3.9 350 1.8 9500 8.8 47.8 300 5 2 7.1 3.9 23.9 74.9 -4.2 327 1.7 9250 9.3 48.7 295 3 1 6.8 3.7 23.6 74.6 -4.4 304 1.5 9000 9.8 49.6 255 1 1 6.6 3.6 23.4 74.1 -4.6 282 1.4 8750 10.3 50.5 200 1 0 6.6 3.6 23.2 73.7 -4.9 259 1.3 8500 10.8 51.4 165 1 1 6.6 3.6 22.9 73.2 -5.1 237 1.2 8250 11.3 52.3 190 4 2 6.7 3.7 22.7 72.8 -5.3 214 1.1 8000 11.8 53.2 155 6 3 6.3 3.5 22.4 72.4 -5.6 192 1.0 7750 12.2 54.0 155 7 3 2.9 1.6 22.1 71.7 -6.0 173 0.9 7500 12.3 54.1 150 9 5 0.9 0.5 21.4 70.5 -6.7 164 0.8 7250 12.3 54.1 145 11 6 1.0 0.6 20.8 69.4 -7.3 155 0.8 7000 12.4 54.3 135 9 5 2.7 1.5 20.1 68.2 -8.0 146 0.7 6750 12.7 54.9 130 8 4 4.3 2.4 19.7 67.4 -8.5 130 0.7 6500 13.0 55.4 120 7 4 6.4 3.5 19.3 66.7 -8.9 113 0.6 6250 13.6 56.5 115 7 4 7.1 3.9 19.1 66.4 -9.1 89 0.5 6000 13.8 56.8 120 8 4 -1.8 -1.0 18.6 65.5 -9.6 75 0.4 5750 13.4 56.1 125 10 5 -6.8 -3.7 17.5 63.4 -10.8 80 0.4 5500 13.1 55.6 140 12 6 0.8 0.4 16.4 61.6 -11.8 81 0.4 5250 13.3 55.9 145 15 8 2.5 1.4 16.0 60.7 -12.4 67 0.3 5000 13.1 55.6 140 15 8 -9.1 -5.0 15.0 59.0 -13.4 66 0.3 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 09/23/2024 at 0900 MDT | 09/23/2024 at 1200 MDT | CAPE... 0.0 LI... +1.0 | CAPE... +15.8 LI... +0.7 CINH... -0.1 K Index... +21.2 | CINH... -16.5 K Index... +19.0 | 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 -58.9 -74.0 300 21 11 2.3 1.2 | -59.0 -74.2 310 22 11 2.3 1.3 45000 -56.0 -68.8 300 25 13 0.1 0.1 | -56.1 -69.0 310 24 13 0.6 0.3 40000 -55.8 -68.4 325 23 12 1.4 0.8 | -55.2 -67.4 350 24 12 1.9 1.0 38000 -52.6 -62.7 335 25 13 5.7 3.1 | -52.5 -62.5 345 23 12 4.7 2.6 36000 -49.2 -56.6 345 27 14 5.7 3.1 | -49.3 -56.7 335 22 11 4.8 2.6 34000 -44.7 -48.5 350 27 14 7.3 4.0 | -45.3 -49.5 335 22 12 7.6 4.2 32000 -40.4 -40.7 360 25 13 7.3 4.0 | -40.7 -41.3 330 23 12 7.7 4.2 30000 -36.3 -33.3 350 20 11 6.6 3.6 | -36.0 -32.8 335 22 11 8.0 4.4 29000 -34.4 -29.9 340 18 9 6.6 3.6 | -33.6 -28.5 340 21 11 8.0 4.4 28000 -32.4 -26.3 325 16 8 6.5 3.5 | -31.2 -24.2 340 20 10 8.1 4.4 27000 -30.1 -22.2 320 15 8 8.1 4.5 | -29.0 -20.2 340 19 10 7.0 3.9 26000 -27.7 -17.9 320 15 8 8.2 4.5 | -26.9 -16.4 335 18 9 7.0 3.9 25000 -25.3 -13.5 320 15 8 8.1 4.5 | -24.8 -12.6 335 17 9 7.0 3.9 24000 -22.9 -9.2 320 13 7 7.7 4.2 | -22.6 -8.7 330 16 8 7.4 4.1 23000 -20.6 -5.1 315 11 6 7.7 4.2 | -20.4 -4.7 330 14 7 7.5 4.1 22000 -17.8 -0.0 310 8 4 7.7 4.2 | -17.6 0.3 325 13 6 7.5 4.1 21000 -15.6 3.9 305 7 4 7.2 4.0 | -15.4 4.3 325 12 6 7.4 4.1 20000 -13.4 7.9 305 7 3 7.3 4.0 | -13.2 8.2 325 12 6 7.4 4.1 19500 -12.3 9.9 305 6 3 7.4 4.0 | -12.1 10.2 325 11 6 7.5 4.1 19000 -11.3 11.7 305 6 3 5.8 3.2 | -11.0 12.2 325 11 6 6.8 3.7 18500 -10.5 13.1 310 7 3 5.6 3.1 | -10.1 13.8 325 11 6 6.7 3.7 18000 -9.7 14.5 315 7 4 5.6 3.1 | -9.1 15.6 325 11 6 6.6 3.6 17500 -8.9 16.0 315 8 4 5.8 3.2 | -8.1 17.4 325 11 6 6.3 3.5 17000 -8.1 17.4 315 8 4 5.8 3.2 | -7.2 19.0 330 11 6 6.4 3.5 16500 -7.2 19.0 315 9 4 6.0 3.3 | -6.3 20.7 330 11 6 5.9 3.2 16000 -6.3 20.7 315 9 5 6.1 3.3 | -5.5 22.1 330 11 6 5.9 3.3 15500 -5.5 22.1 315 9 5 6.5 3.6 | -4.7 23.5 330 11 6 6.3 3.5 15000 -4.5 23.9 315 8 4 7.0 3.8 | -3.7 25.3 325 10 5 6.6 3.6 14500 -3.5 25.7 315 8 4 7.1 3.9 | -2.8 27.0 325 10 5 6.8 3.7 14000 -2.4 27.7 315 7 4 7.7 4.2 | -1.8 28.8 320 9 5 7.4 4.1 13500 -1.3 29.7 320 7 4 7.7 4.2 | -0.7 30.7 320 8 4 7.4 4.1 13000 -0.2 31.6 320 7 3 8.1 4.4 | 0.4 32.7 315 7 4 7.9 4.4 12500 1.0 33.8 320 6 3 8.0 4.4 | 1.5 34.7 310 7 3 7.9 4.3 12000 2.2 36.0 320 6 3 8.4 4.6 | 2.7 36.9 300 6 3 8.1 4.4 11500 3.4 38.1 320 6 3 8.5 4.7 | 3.9 39.0 295 6 3 8.1 4.4 11000 4.5 40.1 315 6 3 7.6 4.2 | 5.0 41.0 290 6 3 8.3 4.5 10500 5.6 42.1 310 6 3 8.0 4.4 | 6.2 43.2 285 5 3 8.5 4.7 10250 6.2 43.2 305 6 3 6.6 3.6 | 6.8 44.2 280 5 3 6.6 3.6 10000 6.6 43.9 305 5 3 6.5 3.6 | 7.2 45.0 275 5 3 7.0 3.8 9750 7.2 45.0 300 5 2 8.0 4.4 | 7.9 46.2 275 5 2 9.1 5.0 9500 7.7 45.9 300 4 2 7.5 4.1 | 8.5 47.3 275 5 2 8.6 4.7 9250 8.3 46.9 295 4 2 8.1 4.5 | 9.1 48.4 275 4 2 8.5 4.7 9000 8.9 48.0 290 3 2 7.0 3.9 | 9.7 49.5 270 4 2 8.0 4.4 8750 9.3 48.7 280 3 1 5.7 3.1 | 10.3 50.5 270 4 2 7.8 4.3 8500 10.2 50.4 255 2 1 5.7 3.1 | 10.8 51.4 270 3 2 7.7 4.2 8250 10.6 51.1 220 2 1 5.7 3.1 | 11.3 52.3 265 3 2 5.5 3.0 8000 11.0 51.8 190 2 1 6.4 3.5 | 11.7 53.1 255 3 1 6.6 3.6 7750 11.5 52.7 170 2 1 5.6 3.1 | 13.2 55.8 250 2 1 9.9 5.4 7500 11.8 53.2 160 3 1 4.0 2.2 | 13.8 56.8 245 2 1 7.0 3.9 7250 12.1 53.8 155 4 2 3.7 2.1 | 14.3 57.7 240 2 1 7.3 4.0 7000 12.4 54.3 150 4 2 6.0 3.3 | 15.0 59.0 235 2 1 12.6 6.9 6750 12.9 55.2 140 4 2 5.1 2.8 | 16.1 61.0 240 2 1 12.5 6.9 6500 13.2 55.8 135 4 2 3.0 1.6 | 16.8 62.2 235 1 1 9.4 5.2 6250 13.4 56.1 130 4 2 3.0 1.6 | 17.5 63.5 230 1 1 9.3 5.1 6000 13.7 56.7 120 4 2 6.0 3.3 | 18.3 64.9 225 1 1 13.1 7.2 5750 14.4 57.9 115 4 2 13.6 7.4 | 19.7 67.5 235 1 1 25.0 13.7 5500 15.2 59.4 105 3 2 0.1 0.1 | 21.4 70.5 230 1 1 14.7 8.1 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 09/23/2024 at 1500 MDT | 09/23/2024 at 1800 MDT | CAPE... +7.9 LI... +0.8 | CAPE... 0.0 LI... +1.0 CINH... -14.4 K Index... +13.8 | CINH... 0.0 K Index... +15.4 | 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 -60.6 -77.1 330 22 11 1.6 0.9 | -61.3 -78.3 360 25 13 0.6 0.3 45000 -58.1 -72.6 350 29 15 1.3 0.7 | -60.1 -76.2 020 44 23 1.7 1.0 40000 -56.1 -69.0 025 48 24 3.9 2.1 | -57.3 -71.1 025 74 38 6.2 3.4 38000 -52.4 -62.3 025 50 26 6.2 3.4 | -52.7 -62.9 030 74 38 7.8 4.3 36000 -48.6 -55.5 030 53 27 6.2 3.4 | -47.4 -53.3 035 75 39 7.8 4.3 34000 -43.9 -47.0 025 47 24 7.5 4.1 | -42.6 -44.7 030 67 35 8.1 4.4 32000 -39.4 -38.9 020 37 19 7.6 4.1 | -37.8 -36.0 030 57 29 8.1 4.4 30000 -34.9 -30.8 010 30 15 7.4 4.1 | -33.1 -27.6 025 48 25 7.7 4.2 29000 -32.7 -26.9 360 27 14 7.4 4.1 | -30.8 -23.4 025 44 23 7.8 4.3 28000 -30.5 -22.9 355 25 13 7.4 4.1 | -28.5 -19.3 020 40 21 7.9 4.3 27000 -28.2 -18.8 350 23 12 7.7 4.2 | -26.4 -15.5 015 35 18 6.9 3.8 26000 -25.9 -14.6 345 22 12 7.7 4.2 | -24.3 -11.7 010 30 15 6.9 3.8 25000 -23.6 -10.5 340 21 11 7.7 4.2 | -22.2 -8.0 360 25 13 6.9 3.8 24000 -21.4 -6.5 335 20 10 6.9 3.8 | -20.2 -4.4 355 22 11 6.5 3.6 23000 -19.3 -2.7 330 19 10 6.9 3.8 | -18.3 -0.9 345 21 11 6.5 3.6 22000 -17.3 0.9 325 17 9 6.9 3.8 | -15.9 3.4 340 20 10 6.5 3.5 21000 -14.7 5.5 320 15 8 6.9 3.8 | -14.0 6.8 335 18 9 6.0 3.3 20000 -12.7 9.1 325 14 7 6.9 3.8 | -12.2 10.0 325 16 8 6.0 3.3 19500 -11.6 11.1 325 13 7 6.9 3.8 | -11.3 11.7 325 15 8 6.0 3.3 19000 -10.6 12.9 325 13 7 7.3 4.0 | -10.4 13.3 320 14 7 6.3 3.5 18500 -9.5 14.9 325 12 6 7.3 4.0 | -9.5 14.9 320 13 7 6.4 3.5 18000 -8.4 16.9 330 12 6 7.2 3.9 | -8.5 16.7 320 13 7 6.5 3.5 17500 -7.4 18.7 330 11 6 6.7 3.7 | -7.6 18.3 325 12 6 6.7 3.7 17000 -6.4 20.5 330 11 6 6.8 3.8 | -6.6 20.1 325 12 6 6.7 3.7 16500 -5.5 22.1 330 10 5 6.1 3.4 | -5.6 21.9 325 11 6 7.1 3.9 16000 -4.6 23.7 330 10 5 6.2 3.4 | -4.6 23.7 325 11 6 7.1 3.9 15500 -3.7 25.3 330 9 5 6.4 3.5 | -3.6 25.5 330 11 6 7.4 4.0 15000 -2.8 27.0 325 9 4 6.6 3.6 | -2.5 27.5 330 11 6 7.5 4.1 14500 -1.9 28.6 320 8 4 6.8 3.8 | -1.4 29.5 330 11 6 7.8 4.3 14000 -0.8 30.6 315 8 4 7.5 4.1 | -0.2 31.6 330 11 6 8.6 4.7 13500 0.2 32.4 310 8 4 7.6 4.1 | 1.0 33.8 330 11 6 8.6 4.7 13000 1.3 34.3 310 8 4 8.0 4.4 | 2.3 36.1 330 11 6 8.8 4.8 12500 2.5 36.5 305 7 4 7.9 4.3 | 3.5 38.3 325 10 5 8.8 4.8 12000 3.7 38.7 300 7 4 8.8 4.8 | 4.8 40.6 325 10 5 8.6 4.7 11500 4.9 40.8 295 7 4 8.8 4.8 | 6.1 43.0 320 9 5 8.7 4.8 11000 6.2 43.2 295 7 4 8.2 4.5 | 7.3 45.1 315 9 5 8.1 4.5 10500 7.4 45.3 290 7 4 7.6 4.1 | 8.5 47.3 315 8 4 7.8 4.3 10250 8.0 46.4 290 7 4 10.8 6.0 | 9.2 48.6 310 8 4 10.2 5.6 10000 8.9 48.0 290 7 4 11.6 6.4 | 10.0 50.0 305 8 4 10.6 5.8 9750 9.6 49.3 290 7 4 8.7 4.8 | 10.7 51.3 300 8 4 8.7 4.7 9500 10.3 50.5 285 7 3 9.9 5.4 | 11.3 52.3 300 8 4 9.3 5.1 9250 11.0 51.8 285 7 3 7.8 4.3 | 12.0 53.6 295 8 4 8.8 4.8 9000 11.5 52.7 285 7 3 8.1 4.4 | 12.7 54.9 295 7 4 8.9 4.9 8750 12.2 54.0 285 7 3 10.0 5.5 | 13.3 55.9 295 7 4 9.2 5.1 8500 12.9 55.2 285 6 3 9.6 5.3 | 14.0 57.2 290 7 4 9.4 5.1 8250 13.6 56.5 285 6 3 7.4 4.1 | 14.7 58.5 290 7 4 7.6 4.2 8000 14.1 57.4 285 6 3 8.1 4.4 | 15.9 60.6 285 7 4 10.4 5.7 7750 15.7 60.3 285 6 3 10.7 5.8 | 16.7 62.1 285 7 4 9.8 5.4 7500 16.4 61.5 285 6 3 7.8 4.3 | 17.3 63.1 285 7 4 7.6 4.2 7250 16.9 62.4 285 6 3 7.6 4.2 | 17.8 64.0 285 7 4 7.2 3.9 7000 17.6 63.7 285 6 3 12.6 6.9 | 18.4 65.1 285 7 4 10.4 5.7 6750 18.7 65.7 285 6 3 12.5 6.8 | 19.3 66.7 285 7 4 11.1 6.1 6500 19.4 66.9 285 6 3 9.6 5.3 | 20.0 68.0 285 7 4 9.9 5.4 6250 20.2 68.4 285 6 3 9.4 5.2 | 20.8 69.4 285 7 4 10.0 5.5 6000 20.9 69.6 290 6 3 11.8 6.5 | 21.5 70.7 285 7 3 9.0 5.0 5750 22.1 71.8 285 5 3 22.5 12.3 | 22.2 72.0 285 6 3 10.0 5.5 5500 24.2 75.6 290 5 3 32.3 17.7 | 23.3 73.9 285 6 3 24.9 13.6 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 ________________________________________________________________________________ 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