Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
109 UXUS97 KGJT 141306 SRGGJT Soaring Forecast National Weather Service Grand Junction, Colorado 706 AM MDT Wednesday, August 14, 2024 This forecast is for Wednesday, August 14, 2024: If the trigger temperature of 75.0 F/23.9 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 959 ft/min (4.9 m/s) Maximum height of thermals.................. 14570 ft MSL (9731 ft AGL) Forecast maximum temperature................... 87.0 F/31.0 C Time of trigger temperature.................... 1045 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................. 10993 ft MSL (6154 ft AGL) Thermal soaring outlook for Thursday 08/15..... Excellent Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 06:27:16 / 20:10:05 MDT Total possible sunshine........... 13 hr 42 min 48 sec (822 min 48 sec) Altitude of sun at 13:18:41 MDT... 64.57 degrees Upper air data from rawinsonde observation taken on 08/14/2024 at 0600 MDT Freezing level.................. 15064 ft MSL (10225 ft AGL) Convective condensation level... 12016 ft MSL (7177 ft AGL) Lifted condensation level....... 13183 ft MSL (8344 ft AGL) Lifted index.................... -4.1 K index......................... +25.9 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 -65.3 -85.5 245 22 11 4.1 2.2 84.5 184.1 31.4 M M 45000 -54.4 -65.9 265 41 21 9.6 5.3 78.3 172.9 29.7 M M 40000 -49.0 -56.2 255 43 22 1.8 1.0 63.9 147.0 22.2 M M 38000 -46.7 -52.1 270 49 25 5.4 3.0 58.5 137.4 19.1 M M 36000 -43.6 -46.5 275 43 22 4.7 2.6 54.6 130.2 16.8 M M 34000 -39.0 -38.2 290 52 27 7.1 3.9 51.7 125.1 15.3 M M 32000 -34.2 -29.6 275 43 22 7.0 3.8 50.3 122.5 14.6 M M 30000 -29.8 -21.6 270 47 24 6.5 3.6 48.3 119.0 13.5 M M 29000 -27.5 -17.5 265 47 24 8.3 4.6 47.5 117.5 13.0 M M 28000 -25.0 -13.0 265 47 24 7.9 4.4 47.0 116.5 12.7 M M 27000 -23.1 -9.6 275 35 18 6.1 3.3 45.7 114.2 11.9 M M 26000 -21.3 -6.3 270 30 16 6.1 3.4 44.3 111.7 10.9 M M 25000 -19.5 -3.1 275 39 20 6.1 3.4 42.9 109.2 9.9 M M 24000 -17.7 0.1 275 36 18 6.4 3.5 41.5 106.7 8.9 M M 23000 -15.2 4.6 270 32 17 9.0 4.9 40.9 105.6 8.5 M M 22000 -13.8 7.2 265 28 15 3.8 2.1 39.1 102.4 7.1 M M 21000 -13.1 8.4 265 26 13 1.8 1.0 36.4 97.6 4.9 M M 20000 -12.3 9.9 275 19 10 7.2 4.0 34.2 93.5 2.8 M M 19500 -11.3 11.7 285 19 10 6.7 3.7 33.7 92.6 2.4 M M 19000 -10.2 13.6 290 20 10 9.4 5.1 33.3 92.0 2.0 M M 18500 -8.1 17.4 290 19 10 8.2 4.5 33.3 91.9 2.0 M M 18000 -7.1 19.2 290 19 10 7.6 4.2 32.8 91.0 1.5 M M 17500 -5.8 21.6 290 17 9 9.3 5.1 32.6 90.7 1.4 M M 17000 -4.5 23.9 280 20 10 7.7 4.2 32.5 90.4 1.2 M M 16500 -3.5 25.7 280 20 10 8.0 4.4 32.1 89.7 0.8 M M 16000 -2.2 28.0 280 20 10 9.4 5.1 31.9 89.4 0.6 M M 15500 -0.9 30.4 275 19 10 9.0 4.9 31.8 89.3 0.4 M M 15000 0.3 32.5 270 22 11 8.0 4.4 31.6 88.9 0.2 M M 14500 1.5 34.7 275 23 12 8.0 4.4 31.3 88.4 -0.1 746 3.8 14000 2.7 36.9 275 23 12 8.1 4.5 31.0 87.9 -0.3 695 3.5 13500 3.5 38.3 270 20 10 2.5 1.4 30.5 86.9 -1.0 655 3.3 13000 3.9 39.0 260 18 9 8.0 4.4 29.6 85.2 -2.0 628 3.2 12500 5.2 41.4 250 17 9 8.1 4.5 29.3 84.8 -2.3 576 2.9 12000 6.4 43.5 245 12 6 8.1 4.5 29.1 84.3 -2.5 525 2.7 11500 7.6 45.7 240 13 7 8.1 4.4 28.8 83.8 -2.7 473 2.4 11000 8.8 47.8 245 14 7 6.9 3.8 28.5 83.3 -3.0 422 2.1 10500 9.7 49.5 235 8 4 6.1 3.3 27.9 82.2 -3.6 382 1.9 10250 10.1 50.2 225 9 5 6.4 3.5 27.6 81.7 -3.9 362 1.8 10000 10.6 51.1 220 10 5 6.0 3.3 27.3 81.2 -4.2 341 1.7 9750 11.0 51.8 215 8 4 7.4 4.1 27.1 80.7 -4.5 320 1.6 9500 11.4 52.5 220 7 4 -1.1 -0.6 26.7 80.1 -4.9 302 1.5 9250 11.0 51.8 210 7 4 0.2 0.1 25.6 78.1 -6.0 305 1.6 9000 11.5 52.7 180 11 5 8.8 4.8 25.4 77.7 -6.2 282 1.4 8750 12.0 53.6 170 12 6 6.2 3.4 25.2 77.3 -6.5 260 1.3 8500 12.5 54.5 155 11 6 5.0 2.7 24.9 76.8 -6.8 240 1.2 8250 12.7 54.9 140 9 5 3.8 2.1 24.4 76.0 -7.3 226 1.1 8000 12.9 55.2 120 9 5 4.2 2.3 24.0 75.2 -7.9 213 1.1 7750 13.1 55.6 115 10 5 4.2 2.3 23.6 74.4 -8.4 198 1.0 7500 13.4 56.1 110 11 6 4.0 2.2 23.2 73.7 -8.9 183 0.9 7250 13.7 56.7 120 9 5 4.9 2.7 22.7 72.9 -9.3 167 0.8 7000 14.1 57.4 115 12 6 7.8 4.3 22.5 72.4 -9.6 147 0.7 6750 14.7 58.5 115 12 6 8.9 4.9 22.4 72.3 -9.8 121 0.6 6500 15.3 59.5 115 12 6 8.7 4.8 22.3 72.2 -9.9 95 0.5 6250 15.9 60.6 125 10 5 8.6 4.7 22.2 72.0 -10.0 69 0.3 6000 16.6 61.9 125 12 6 9.1 5.0 22.2 71.9 -10.2 43 0.2 5750 17.2 63.0 125 13 7 7.4 4.0 22.1 71.7 -10.3 17 0.1 5500 17.4 63.3 130 15 8 -4.3 -2.3 21.5 70.8 -10.9 4 0.0 5250 16.6 61.9 130 12 6 -13.8 -7.6 20.0 68.0 -12.4 19 0.1 5000 15.9 60.6 130 9 5 -3.6 -2.0 18.5 65.3 -13.9 33 0.2 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 08/14/2024 at 0900 MDT | 08/14/2024 at 1200 MDT | CAPE... +418.3 LI... -2.4 | CAPE... +901.3 LI... -4.7 CINH... -111.1 K Index... +26.7 | CINH... -12.9 K Index... +25.9 | 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 -61.7 -79.1 265 33 17 2.2 1.2 | -61.2 -78.2 260 31 16 1.9 1.0 45000 -56.2 -69.2 270 47 24 6.6 3.6 | -56.3 -69.3 265 45 23 6.1 3.3 40000 -47.0 -52.6 270 52 27 2.9 1.6 | -47.6 -53.7 265 54 28 3.3 1.8 38000 -45.3 -49.5 280 58 30 2.8 1.6 | -45.7 -50.3 280 63 32 3.2 1.8 36000 -43.4 -46.1 285 67 35 3.3 1.8 | -43.5 -46.3 285 75 39 3.7 2.0 34000 -39.3 -38.7 285 62 32 7.1 3.9 | -39.3 -38.7 285 70 36 7.3 4.0 32000 -35.1 -31.2 285 56 29 7.1 3.9 | -35.0 -31.0 285 63 33 7.3 4.0 30000 -30.8 -23.4 280 50 26 7.1 3.9 | -30.7 -23.3 280 57 29 7.2 4.0 29000 -28.7 -19.7 275 47 24 7.1 3.9 | -28.5 -19.3 280 54 28 7.2 4.0 28000 -26.5 -15.7 270 45 23 7.5 4.1 | -26.3 -15.3 280 51 26 7.4 4.0 27000 -24.2 -11.6 270 43 22 7.8 4.3 | -24.1 -11.4 275 48 25 7.5 4.1 26000 -21.9 -7.4 265 42 21 7.8 4.3 | -21.9 -7.4 270 44 23 7.5 4.1 25000 -19.5 -3.1 265 40 21 8.1 4.4 | -19.6 -3.3 265 41 21 7.7 4.2 24000 -17.7 0.1 265 37 19 5.7 3.1 | -17.7 0.1 265 38 20 6.0 3.3 23000 -15.9 3.4 265 34 17 5.8 3.2 | -15.9 3.4 265 36 18 6.0 3.3 22000 -13.8 7.2 270 29 15 5.8 3.2 | -13.7 7.3 260 32 17 5.5 3.0 21000 -12.1 10.2 265 25 13 5.9 3.2 | -12.2 10.0 260 28 14 5.3 2.9 20000 -10.4 13.3 265 21 11 5.9 3.3 | -10.6 12.9 255 23 12 5.4 3.0 19500 -9.5 14.9 260 19 10 6.0 3.3 | -9.8 14.4 255 21 11 5.6 3.1 19000 -8.6 16.5 260 17 9 6.3 3.4 | -8.9 16.0 255 19 10 6.8 3.7 18500 -7.7 18.1 260 16 8 6.4 3.5 | -8.0 17.6 255 18 9 6.8 3.8 18000 -6.9 19.6 255 15 8 6.5 3.5 | -7.0 19.4 255 17 9 6.9 3.8 17500 -6.0 21.2 255 14 7 6.5 3.6 | -6.0 21.2 250 16 8 7.0 3.8 17000 -5.1 22.8 255 13 7 6.8 3.7 | -5.1 22.8 250 15 8 7.2 3.9 16500 -4.0 24.8 260 12 6 7.6 4.1 | -4.0 24.8 250 14 7 7.6 4.2 16000 -2.9 26.8 260 12 6 7.5 4.1 | -2.9 26.8 250 13 7 7.5 4.1 15500 -1.8 28.8 260 11 6 8.2 4.5 | -1.8 28.8 250 13 7 8.5 4.7 15000 -0.6 30.9 260 12 6 8.2 4.5 | -0.5 31.1 250 13 7 8.5 4.6 14500 0.6 33.1 260 12 6 8.5 4.7 | 0.7 33.3 255 13 7 8.7 4.8 14000 1.8 35.2 260 13 7 8.6 4.7 | 2.0 35.6 255 13 7 8.8 4.8 13500 3.0 37.4 255 14 7 8.6 4.7 | 3.3 37.9 255 13 7 8.8 4.8 13000 4.3 39.7 255 14 7 8.6 4.7 | 4.6 40.3 255 14 7 8.8 4.8 12500 5.5 41.9 250 15 8 8.5 4.7 | 5.8 42.4 255 14 7 8.7 4.8 12000 6.7 44.1 250 16 8 8.3 4.5 | 7.1 44.8 250 14 7 8.6 4.7 11500 7.9 46.2 250 16 8 8.3 4.5 | 8.3 46.9 250 14 7 8.5 4.7 11000 9.0 48.2 245 16 8 7.8 4.3 | 9.5 49.1 250 14 7 7.8 4.3 10500 10.1 50.2 245 15 8 6.9 3.8 | 10.6 51.1 245 14 7 6.1 3.3 10250 10.6 51.1 245 15 8 6.5 3.5 | 10.9 51.6 245 15 8 6.5 3.5 10000 11.1 52.0 245 14 7 7.8 4.3 | 11.5 52.7 245 14 7 9.3 5.1 9750 11.7 53.1 240 13 7 8.0 4.4 | 12.1 53.8 245 13 7 8.6 4.7 9500 12.2 54.0 240 12 6 7.6 4.2 | 12.7 54.9 245 13 7 8.6 4.7 9250 12.7 54.9 235 11 6 6.4 3.5 | 13.2 55.8 240 12 6 8.1 4.4 9000 13.1 55.6 235 10 5 5.7 3.2 | 13.8 56.8 240 11 6 8.1 4.5 8750 13.5 56.3 230 9 5 5.7 3.1 | 14.4 57.9 240 10 5 8.5 4.6 8500 13.9 57.0 220 8 4 5.8 3.2 | 15.0 59.0 235 9 5 8.0 4.4 8250 14.8 58.6 205 7 4 5.6 3.1 | 16.0 60.8 235 7 4 8.2 4.5 8000 15.2 59.4 195 7 4 4.9 2.7 | 16.7 62.1 235 7 3 10.9 6.0 7750 15.5 59.9 185 7 4 4.5 2.5 | 17.4 63.3 230 7 3 9.5 5.2 7500 15.8 60.4 180 7 4 4.2 2.3 | 18.0 64.4 230 6 3 7.8 4.3 7250 16.1 61.0 175 7 4 4.4 2.4 | 18.6 65.5 230 5 3 9.0 4.9 7000 16.4 61.5 165 7 4 5.4 3.0 | 19.4 66.9 230 5 3 11.9 6.5 6750 16.8 62.2 160 7 3 6.0 3.3 | 20.3 68.5 230 5 3 11.1 6.1 6500 17.2 63.0 155 6 3 5.9 3.2 | 21.0 69.8 225 5 2 9.7 5.3 6250 17.6 63.7 150 6 3 5.7 3.1 | 21.8 71.2 225 4 2 8.9 4.9 6000 18.1 64.6 145 6 3 9.6 5.3 | 22.5 72.5 225 4 2 14.0 7.7 5750 19.0 66.2 140 4 2 16.4 9.0 | 24.0 75.2 225 4 2 27.1 14.9 5500 19.8 67.6 130 4 2 1.3 0.7 | 25.7 78.3 225 3 2 9.2 5.0 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 08/14/2024 at 1500 MDT | 08/14/2024 at 1800 MDT | CAPE... +251.1 LI... -1.9 | CAPE... +0.4 LI... +0.5 CINH... -1.6 K Index... +24.7 | CINH... -2.3 K Index... +18.3 | 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 -61.4 -78.5 265 34 18 1.8 1.0 | -61.9 -79.4 275 34 18 1.6 0.9 45000 -57.0 -70.6 265 51 26 5.3 2.9 | -57.7 -71.9 275 56 29 5.0 2.8 40000 -49.2 -56.6 275 61 32 4.7 2.6 | -50.0 -58.0 285 72 37 5.6 3.1 38000 -46.1 -51.0 280 70 36 4.6 2.5 | -46.3 -51.3 285 75 39 5.6 3.1 36000 -43.3 -45.9 285 78 40 5.1 2.8 | -42.9 -45.2 285 78 40 6.0 3.3 34000 -39.0 -38.2 285 74 38 7.3 4.0 | -38.6 -37.5 285 75 38 7.2 3.9 32000 -34.6 -30.3 290 69 35 7.3 4.0 | -34.3 -29.7 290 71 37 7.2 3.9 30000 -30.3 -22.5 285 64 33 7.1 3.9 | -30.2 -22.4 290 66 34 6.8 3.7 29000 -28.2 -18.8 285 62 32 7.1 3.9 | -28.2 -18.8 290 64 33 6.8 3.7 28000 -26.0 -14.8 285 60 31 7.1 3.9 | -26.1 -15.0 290 61 32 7.1 3.9 27000 -23.9 -11.0 285 55 28 7.0 3.9 | -24.0 -11.2 290 57 29 7.3 4.0 26000 -21.8 -7.2 280 50 26 7.0 3.9 | -21.8 -7.2 285 53 27 7.3 4.0 25000 -19.7 -3.5 280 46 23 7.1 3.9 | -19.6 -3.3 285 48 25 7.3 4.0 24000 -17.7 0.1 275 42 22 6.6 3.6 | -17.7 0.1 280 44 23 6.2 3.4 23000 -15.2 4.6 265 38 19 6.6 3.6 | -15.3 4.5 275 39 20 6.2 3.4 22000 -13.3 8.1 260 35 18 5.8 3.2 | -13.5 7.7 270 35 18 6.4 3.5 21000 -11.7 10.9 260 31 16 5.4 2.9 | -11.6 11.1 270 32 17 6.5 3.6 20000 -10.1 13.8 260 27 14 5.4 3.0 | -9.6 14.7 270 29 15 6.6 3.6 19500 -9.4 15.1 255 25 13 5.6 3.1 | -8.7 16.3 270 28 14 6.5 3.6 19000 -8.5 16.7 255 23 12 6.4 3.5 | -7.8 18.0 270 26 13 6.2 3.4 18500 -7.6 18.3 255 21 11 6.4 3.5 | -6.9 19.6 270 24 13 6.2 3.4 18000 -6.6 20.1 250 19 10 7.2 3.9 | -5.9 21.4 270 23 12 7.3 4.0 17500 -5.6 21.9 250 18 9 7.4 4.1 | -4.8 23.4 270 21 11 7.5 4.1 17000 -4.5 23.9 245 17 9 7.6 4.2 | -3.7 25.3 270 19 10 7.7 4.2 16500 -3.4 25.9 245 16 8 8.0 4.4 | -2.6 27.3 270 18 9 8.0 4.4 16000 -2.3 27.9 245 15 8 8.0 4.4 | -1.5 29.3 265 17 9 7.9 4.3 15500 -1.1 30.0 245 15 8 8.3 4.6 | -0.2 31.6 260 17 9 9.0 5.0 15000 0.1 32.2 245 14 7 8.3 4.6 | 1.1 34.0 260 16 8 9.0 4.9 14500 1.3 34.3 245 14 7 8.7 4.8 | 2.4 36.3 255 16 8 8.9 4.9 14000 2.6 36.7 245 13 7 8.8 4.8 | 3.7 38.7 255 16 8 8.9 4.9 13500 3.8 38.8 245 13 7 9.0 4.9 | 4.9 40.8 255 15 8 9.1 5.0 13000 5.2 41.4 245 13 7 9.1 5.0 | 6.3 43.3 255 15 8 9.2 5.0 12500 6.5 43.7 245 13 7 9.2 5.0 | 7.6 45.7 255 14 7 9.2 5.0 12000 7.8 46.0 245 13 7 9.2 5.0 | 9.0 48.2 255 14 7 9.1 5.0 11500 9.2 48.6 250 13 7 9.2 5.1 | 10.3 50.5 255 14 7 9.1 5.0 11000 10.5 50.9 250 13 7 9.2 5.1 | 11.7 53.1 255 13 7 9.1 5.0 10500 11.9 53.4 250 13 7 7.1 3.9 | 13.0 55.4 255 13 7 7.5 4.1 10250 12.4 54.3 250 12 6 7.7 4.2 | 13.5 56.3 255 13 7 8.0 4.4 10000 13.1 55.6 250 12 6 11.1 6.1 | 14.3 57.7 255 13 7 10.4 5.7 9750 13.9 57.0 250 12 6 10.2 5.6 | 15.0 59.0 255 12 6 9.9 5.4 9500 14.7 58.5 250 12 6 10.3 5.6 | 15.8 60.4 255 12 6 9.8 5.4 9250 15.4 59.7 250 12 6 9.7 5.3 | 16.4 61.5 260 12 6 9.2 5.1 9000 16.1 61.0 255 12 6 9.6 5.2 | 17.1 62.8 260 12 6 9.4 5.2 8750 16.8 62.2 255 12 6 9.8 5.3 | 17.8 64.0 260 12 6 9.7 5.3 8500 18.1 64.6 255 12 6 8.3 4.6 | 19.2 66.6 260 12 6 8.3 4.5 8250 18.8 65.8 260 12 6 9.6 5.3 | 19.8 67.6 260 12 6 9.3 5.1 8000 19.6 67.3 255 12 6 11.7 6.4 | 20.6 69.1 260 11 6 11.1 6.1 7750 20.4 68.7 255 12 6 10.1 5.5 | 21.4 70.5 260 11 6 9.8 5.4 7500 21.1 70.0 260 12 6 8.3 4.5 | 22.0 71.6 260 11 6 8.2 4.5 7250 21.7 71.1 260 11 6 9.2 5.1 | 22.7 72.9 260 12 6 9.1 5.0 7000 22.5 72.5 260 11 6 11.9 6.5 | 23.4 74.1 260 11 6 11.6 6.4 6750 23.4 74.1 260 11 6 11.5 6.3 | 24.3 75.7 260 11 6 11.2 6.1 6500 24.2 75.6 260 11 6 10.6 5.8 | 25.1 77.2 260 11 6 10.0 5.5 6250 25.0 77.0 265 11 6 9.5 5.2 | 25.8 78.4 265 11 6 9.7 5.3 6000 25.7 78.3 265 11 5 13.2 7.3 | 26.6 79.9 265 11 5 10.7 5.9 5750 27.2 81.0 265 10 5 27.1 14.9 | 27.5 81.5 265 9 5 17.1 9.4 5500 29.3 84.7 270 9 5 23.4 12.8 | 29.0 84.2 265 9 5 20.2 11.1 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 ________________________________________________________________________________ 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