Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
629 UXUS97 KGJT 211307 SRGGJT Soaring Forecast National Weather Service Grand Junction, Colorado 707 AM MDT Saturday, September 21, 2024 This forecast is for Saturday, September 21, 2024: If the trigger temperature of 78.3 F/25.7 C is reached...then Thermal Soaring Index....................... Poor Maximum rate of lift........................ 0 ft/min (0.0 m/s) Maximum height of thermals.................. 8095 ft MSL (3256 ft AGL) Forecast maximum temperature................... 77.0 F/25.5 C Time of trigger temperature.................... 1415 MDT Time of overdevelopment........................ None Middle/high clouds during soaring window....... Broken/overcast opaque middle Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 5814 ft MSL (975 ft AGL) Thermal soaring outlook for Sunday 09/22....... Fair Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 07:01:44 / 19:12:10 MDT Total possible sunshine........... 12 hr 10 min 27 sec (730 min 27 sec) Altitude of sun at 13:06:57 MDT... 51.14 degrees Upper air data from rawinsonde observation taken on 09/21/2024 at 0600 MDT Freezing level.................. 14202 ft MSL (9363 ft AGL) Convective condensation level... 17526 ft MSL (12687 ft AGL) Lifted condensation level....... 16082 ft MSL (11242 ft AGL) Lifted index.................... +3.3 K index......................... +16.6 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 -62.6 -80.7 220 42 21 5.2 2.9 90.9 195.5 38.1 M M 45000 -56.1 -69.0 220 52 27 4.4 2.4 77.2 170.9 32.3 M M 40000 -49.7 -57.5 215 79 40 3.6 2.0 64.4 147.9 26.1 M M 38000 -47.9 -54.2 215 79 40 2.2 1.2 58.4 137.1 22.7 M M 36000 -46.0 -50.8 210 72 37 6.5 3.6 51.5 124.7 18.6 M M 34000 -43.0 -45.4 210 70 36 4.7 2.6 47.6 117.7 16.2 M M 32000 -39.9 -39.8 210 59 30 7.6 4.2 43.7 110.6 13.7 M M 30000 -36.0 -32.8 210 47 24 6.1 3.3 41.2 106.1 12.2 M M 29000 -33.5 -28.3 210 44 23 8.2 4.5 40.5 104.9 11.8 M M 28000 -31.0 -23.8 205 37 19 8.2 4.5 39.9 103.9 11.5 M M 27000 -28.6 -19.5 200 40 21 8.6 4.7 39.3 102.8 11.2 M M 26000 -26.0 -14.8 195 39 20 8.0 4.4 38.9 102.0 11.0 M M 25000 -23.8 -10.8 200 44 23 3.8 2.1 38.0 100.4 10.4 M M 24000 -22.1 -7.8 195 36 18 7.4 4.1 36.5 97.7 9.3 M M 23000 -19.9 -3.8 200 33 17 6.9 3.8 35.6 96.1 8.7 M M 22000 -17.7 0.1 200 29 15 8.1 4.4 34.7 94.5 8.1 M M 21000 -15.4 4.3 195 20 10 5.9 3.3 33.9 93.1 7.5 M M 20000 -14.3 6.3 195 22 11 1.9 1.1 31.9 89.4 5.8 M M 19500 -13.5 7.7 190 23 12 6.7 3.7 31.1 88.1 5.1 M M 19000 -12.2 10.0 190 26 13 7.3 4.0 30.2 86.3 4.2 M M 18500 -11.1 12.0 190 27 14 7.8 4.3 29.8 85.7 3.9 M M 18000 -10.0 14.0 190 24 12 7.8 4.3 29.5 85.1 3.6 M M 17500 -8.8 16.2 195 23 12 9.1 5.0 29.3 84.7 3.4 M M 17000 -7.4 18.7 195 21 11 9.0 5.0 29.2 84.6 3.3 M M 16500 -6.1 21.0 195 18 9 9.0 4.9 29.1 84.4 3.2 M M 16000 -4.7 23.5 190 15 7 9.0 4.9 29.0 84.2 3.2 M M 15500 -3.4 25.9 185 12 6 9.0 4.9 28.9 84.0 3.1 M M 15000 -2.0 28.4 180 9 5 9.0 4.9 28.8 83.8 3.0 M M 14500 -0.7 30.7 190 10 5 9.0 4.9 28.6 83.5 2.9 M M 14000 0.7 33.3 190 9 5 9.0 4.9 28.5 83.3 2.7 M M 13500 2.0 35.6 190 8 4 9.0 5.0 28.3 83.0 2.6 M M 13000 3.4 38.1 210 11 6 9.1 5.0 28.2 82.7 2.5 M M 12500 4.7 40.5 195 6 3 8.5 4.6 28.0 82.4 2.3 M M 12000 6.0 42.8 115 3 1 9.2 5.0 27.8 82.1 2.1 M M 11500 7.3 45.1 150 3 2 9.4 5.1 27.8 82.0 2.1 M M 11000 8.7 47.7 160 4 2 9.4 5.1 27.7 81.9 2.0 M M 10500 10.1 50.2 090 6 3 9.0 4.9 27.7 81.8 1.9 M M 10250 10.7 51.3 095 8 4 7.8 4.3 27.6 81.6 1.8 M M 10000 11.3 52.3 105 10 5 8.0 4.4 27.4 81.3 1.7 M M 9750 11.9 53.4 100 10 5 8.0 4.4 27.3 81.1 1.5 M M 9500 12.4 54.3 085 11 6 6.8 3.8 27.1 80.8 1.3 M M 9250 12.9 55.2 085 10 5 6.4 3.5 26.8 80.3 1.1 M M 9000 13.4 56.1 090 8 4 6.5 3.6 26.6 79.9 0.9 M M 8750 13.9 57.0 090 7 4 6.5 3.5 26.3 79.4 0.7 M M 8500 14.4 57.9 085 7 3 6.5 3.6 26.1 78.9 0.4 M M 8250 14.9 58.8 085 6 3 6.5 3.6 25.8 78.5 0.2 M M 8000 15.4 59.7 080 8 4 6.5 3.5 25.6 78.0 -0.1 193 1.0 7750 15.9 60.6 080 8 4 6.5 3.6 25.3 77.6 -0.3 171 0.9 7500 16.4 61.5 085 10 5 6.3 3.4 25.1 77.1 -0.5 149 0.8 7250 16.8 62.2 090 11 6 5.1 2.8 24.8 76.6 -0.8 129 0.7 7000 17.2 63.0 095 13 7 6.1 3.3 24.4 75.9 -1.2 110 0.6 6750 17.6 63.7 100 12 6 6.5 3.6 24.2 75.5 -1.4 88 0.4 6500 18.0 64.4 100 13 7 5.7 3.1 23.9 75.0 -1.8 69 0.4 6250 18.4 65.1 095 13 7 5.4 3.0 23.6 74.4 -2.1 50 0.3 6000 18.8 65.8 090 11 6 7.4 4.1 23.3 73.9 -2.4 30 0.2 5750 19.1 66.4 095 10 5 -5.5 -3.0 22.8 73.1 -2.9 15 0.1 5500 18.0 64.4 105 9 5 -17.3 -9.5 21.0 69.8 -4.8 41 0.2 5250 16.9 62.4 115 9 5 -13.3 -7.3 19.1 66.5 -6.7 68 0.3 5000 15.7 60.3 115 8 4 -17.3 -9.5 17.3 63.2 -8.5 94 0.5 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 09/21/2024 at 0900 MDT | 09/21/2024 at 1200 MDT | CAPE... 0.0 LI... +0.9 | CAPE... +5.0 LI... 0.0 CINH... -0.0 K Index... +19.7 | CINH... -20.3 K Index... +21.1 | 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 -59.2 -74.6 220 32 16 1.8 1.0 | -57.4 -71.3 210 28 14 1.7 1.0 45000 -55.7 -68.3 205 43 22 4.3 2.4 | -54.3 -65.7 200 45 23 3.5 1.9 40000 -49.2 -56.6 205 56 29 4.0 2.2 | -49.0 -56.2 195 55 28 3.5 1.9 38000 -47.4 -53.3 205 63 32 3.0 1.6 | -47.3 -53.1 195 58 30 2.8 1.5 36000 -45.4 -49.7 205 70 36 3.0 1.6 | -45.5 -49.9 190 62 32 2.8 1.5 34000 -43.2 -45.8 200 70 36 4.0 2.2 | -43.6 -46.5 185 62 32 3.3 1.8 32000 -40.8 -41.4 195 65 33 4.0 2.2 | -41.7 -43.1 185 59 31 3.3 1.8 30000 -37.3 -35.1 190 56 29 7.4 4.1 | -38.5 -37.3 180 54 28 7.2 3.9 29000 -35.1 -31.2 185 50 26 7.4 4.1 | -36.4 -33.5 180 50 26 7.2 3.9 28000 -32.9 -27.2 180 44 23 7.4 4.1 | -34.2 -29.6 180 47 24 7.2 4.0 27000 -30.5 -22.9 180 41 21 8.4 4.6 | -32.0 -25.6 175 43 22 7.9 4.4 26000 -28.0 -18.4 180 39 20 8.4 4.6 | -29.6 -21.3 175 40 20 8.0 4.4 25000 -25.5 -13.9 180 37 19 8.4 4.6 | -27.2 -17.0 170 37 19 8.0 4.4 24000 -23.1 -9.6 180 35 18 7.4 4.0 | -24.9 -12.8 170 34 17 7.6 4.2 23000 -20.8 -5.4 175 32 17 7.4 4.1 | -22.0 -7.6 165 31 16 7.6 4.2 22000 -18.1 -0.6 175 29 15 7.6 4.1 | -19.8 -3.6 165 30 15 7.7 4.2 21000 -16.2 2.8 175 27 14 6.0 3.3 | -17.6 0.3 165 27 14 7.4 4.0 20000 -14.4 6.1 170 26 13 6.1 3.3 | -15.4 4.3 165 25 13 7.4 4.1 19500 -13.5 7.7 170 25 13 6.1 3.4 | -14.3 6.3 165 24 12 7.4 4.1 19000 -12.6 9.3 170 24 13 6.4 3.5 | -13.2 8.2 160 23 12 7.7 4.3 18500 -11.7 10.9 170 23 12 6.6 3.6 | -12.1 10.2 160 21 11 8.1 4.4 18000 -10.8 12.6 170 22 11 6.6 3.6 | -10.9 12.4 160 20 10 8.0 4.4 17500 -9.7 14.5 170 20 10 9.0 4.9 | -9.7 14.5 160 18 9 9.0 4.9 17000 -8.4 16.9 170 18 10 8.8 4.8 | -8.4 16.9 160 16 8 8.9 4.9 16500 -7.1 19.2 170 17 9 9.1 5.0 | -7.1 19.2 155 15 8 9.2 5.1 16000 -5.8 21.6 165 16 8 9.2 5.1 | -5.7 21.7 155 14 7 9.4 5.2 15500 -4.4 24.1 165 15 7 9.3 5.1 | -4.3 24.3 150 13 7 9.5 5.2 15000 -3.0 26.6 160 14 7 9.5 5.2 | -2.9 26.8 150 13 6 9.4 5.2 14500 -1.6 29.1 155 13 7 9.5 5.2 | -1.5 29.3 145 12 6 9.4 5.2 14000 -0.1 31.8 150 13 7 9.5 5.2 | -0.0 32.0 145 12 6 9.5 5.2 13500 1.3 34.3 150 12 6 9.6 5.2 | 1.4 34.5 145 11 6 9.5 5.2 13000 2.7 36.9 145 12 6 9.4 5.1 | 2.8 37.0 145 11 6 9.2 5.0 12500 4.1 39.4 140 12 6 9.4 5.1 | 4.2 39.6 145 10 5 9.2 5.0 12000 5.5 41.9 140 11 6 9.1 5.0 | 5.5 41.9 140 10 5 8.9 4.9 11500 6.9 44.4 135 11 6 9.1 5.0 | 6.8 44.2 140 9 5 8.9 4.9 11000 8.1 46.6 130 10 5 7.4 4.1 | 8.1 46.6 140 8 4 8.1 4.4 10500 9.2 48.6 130 10 5 6.0 3.3 | 9.3 48.7 140 8 4 7.4 4.1 10250 9.7 49.5 125 10 5 10.5 5.8 | 9.9 49.8 135 8 4 10.5 5.8 10000 10.6 51.1 120 9 5 10.6 5.8 | 10.8 51.4 135 7 3 10.4 5.7 9750 11.1 52.0 120 9 5 5.9 3.2 | 11.4 52.5 130 6 3 7.7 4.2 9500 11.7 53.1 120 9 5 7.6 4.2 | 12.0 53.6 130 6 3 8.2 4.5 9250 12.2 54.0 115 9 5 5.4 3.0 | 12.6 54.7 130 6 3 8.7 4.8 9000 12.5 54.5 120 10 5 5.1 2.8 | 13.3 55.9 125 4 2 8.7 4.8 8750 13.0 55.4 120 9 5 6.6 3.6 | 13.9 57.0 120 4 2 7.8 4.3 8500 13.5 56.3 115 9 4 6.3 3.5 | 14.5 58.1 115 3 2 8.5 4.6 8250 14.3 57.7 115 9 4 4.7 2.6 | 15.5 59.9 115 3 2 6.1 3.3 8000 14.6 58.3 115 8 4 3.8 2.1 | 16.1 61.0 110 3 1 7.8 4.3 7750 14.9 58.8 115 8 4 4.1 2.3 | 16.7 62.1 100 2 1 8.4 4.6 7500 15.2 59.4 110 7 4 2.9 1.6 | 17.2 63.0 085 2 1 6.4 3.5 7250 15.3 59.5 115 8 4 1.8 1.0 | 17.6 63.7 100 2 1 5.2 2.8 7000 15.5 59.9 120 8 4 3.1 1.7 | 18.1 64.6 105 2 1 9.3 5.1 6750 15.8 60.4 110 7 3 3.4 1.8 | 18.9 66.0 090 2 1 11.4 6.2 6500 16.0 60.8 105 6 3 1.9 1.0 | 19.7 67.5 080 1 1 10.1 5.5 6250 16.1 61.0 105 6 3 0.7 0.4 | 20.5 68.9 095 1 1 10.1 5.5 6000 16.2 61.2 105 6 3 3.4 1.9 | 21.2 70.2 105 2 1 8.6 4.7 5750 16.6 61.9 100 5 2 9.4 5.2 | 21.9 71.4 090 1 1 12.9 7.1 5500 17.3 63.1 090 4 2 6.5 3.5 | 24.2 75.6 100 2 1 61.9 33.9 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 09/21/2024 at 1500 MDT | 09/21/2024 at 1800 MDT | CAPE... +107.0 LI... +0.1 | CAPE... +341.3 LI... +0.2 CINH... -62.0 K Index... +25.9 | CINH... -17.2 K Index... +25.6 | 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 -69.9 210 27 14 2.7 1.5 | -56.3 -69.3 230 19 10 2.8 1.5 45000 -52.6 -62.7 205 38 19 2.7 1.5 | -52.2 -62.0 235 26 13 2.8 1.5 40000 -48.6 -55.5 185 41 21 2.9 1.6 | -48.0 -54.4 205 24 12 3.1 1.7 38000 -48.1 -54.6 175 43 22 0.6 0.3 | -48.5 -55.3 160 18 9 -1.6 -0.9 36000 -47.7 -53.9 160 48 25 0.6 0.3 | -49.6 -57.3 110 28 14 -1.6 -0.9 34000 -45.8 -50.4 155 48 25 5.3 2.9 | -47.6 -53.7 100 32 16 7.8 4.3 32000 -42.6 -44.7 155 42 22 5.3 2.9 | -42.9 -45.2 095 26 13 7.8 4.3 30000 -38.6 -37.5 155 38 19 8.0 4.4 | -38.1 -36.6 090 20 10 8.1 4.5 29000 -36.2 -33.2 150 36 18 8.0 4.4 | -35.7 -32.3 090 18 9 8.2 4.5 28000 -33.8 -28.8 150 34 18 8.0 4.4 | -33.3 -27.9 085 15 8 8.2 4.5 27000 -31.5 -24.7 150 33 17 7.9 4.3 | -30.9 -23.6 080 13 7 7.9 4.3 26000 -29.1 -20.4 145 32 17 7.9 4.3 | -28.6 -19.5 070 10 5 7.9 4.3 25000 -26.8 -16.2 145 31 16 7.9 4.3 | -26.2 -15.2 060 8 4 7.9 4.3 24000 -24.4 -11.9 145 31 16 8.1 4.4 | -23.9 -11.0 040 6 3 7.6 4.1 23000 -22.0 -7.6 145 29 15 8.1 4.4 | -21.1 -6.0 020 5 3 7.6 4.2 22000 -19.1 -2.4 145 28 14 8.1 4.4 | -18.9 -2.0 005 5 3 7.7 4.2 21000 -16.8 1.8 145 26 13 7.6 4.2 | -16.7 1.9 350 6 3 7.1 3.9 20000 -14.6 5.7 145 23 12 7.6 4.2 | -14.7 5.5 345 6 3 7.1 3.9 19500 -13.4 7.9 145 22 11 7.6 4.2 | -13.6 7.5 345 7 3 7.1 3.9 19000 -12.3 9.9 145 21 11 7.5 4.1 | -12.6 9.3 345 7 4 6.8 3.8 18500 -11.3 11.7 145 19 10 7.4 4.1 | -11.7 10.9 340 7 4 6.3 3.5 18000 -10.2 13.6 145 17 9 7.4 4.1 | -10.7 12.7 335 8 4 6.4 3.5 17500 -9.1 15.6 140 15 8 7.5 4.1 | -9.8 14.4 325 8 4 6.1 3.3 17000 -8.0 17.6 140 13 7 7.5 4.1 | -8.9 16.0 320 8 4 6.1 3.4 16500 -6.9 19.6 135 11 6 7.5 4.1 | -8.0 17.6 315 8 4 6.2 3.4 16000 -5.8 21.6 130 9 5 7.6 4.1 | -7.1 19.2 310 8 4 6.4 3.5 15500 -4.7 23.5 125 8 4 7.6 4.2 | -6.2 20.8 305 8 4 6.4 3.5 15000 -3.6 25.5 110 6 3 7.6 4.2 | -5.2 22.6 300 8 4 6.3 3.5 14500 -2.5 27.5 095 5 3 7.6 4.2 | -4.3 24.3 295 8 4 6.3 3.5 14000 -1.4 29.5 070 4 2 7.9 4.3 | -3.4 25.9 290 8 4 6.6 3.6 13500 -0.2 31.6 045 4 2 7.9 4.3 | -2.4 27.7 285 8 4 6.6 3.6 13000 0.9 33.6 025 5 3 7.9 4.3 | -1.5 29.3 280 8 4 6.5 3.6 12500 2.1 35.8 010 5 3 7.9 4.3 | -0.5 31.1 280 8 4 6.5 3.6 12000 3.3 37.9 355 6 3 8.0 4.4 | 0.4 32.7 275 9 4 7.0 3.8 11500 4.5 40.1 345 6 3 8.0 4.4 | 1.5 34.7 270 8 4 7.1 3.9 11000 5.7 42.3 335 6 3 7.5 4.1 | 2.5 36.5 270 9 4 7.7 4.2 10500 6.7 44.1 330 6 3 6.4 3.5 | 3.7 38.7 265 9 5 7.9 4.3 10250 7.3 45.1 325 6 3 10.3 5.7 | 4.3 39.7 260 10 5 8.4 4.6 10000 8.2 46.8 310 7 4 10.9 6.0 | 4.9 40.8 270 8 4 8.3 4.6 9750 8.8 47.8 305 7 4 7.5 4.1 | 5.5 41.9 270 8 4 7.9 4.3 9500 9.4 48.9 305 7 4 8.1 4.4 | 6.1 43.0 270 7 4 7.4 4.0 9250 10.0 50.0 305 7 4 9.3 5.1 | 6.7 44.1 270 7 4 9.9 5.4 9000 10.8 51.4 290 8 4 9.7 5.3 | 7.5 45.5 265 8 4 9.0 4.9 8750 11.4 52.5 285 9 4 8.3 4.5 | 7.9 46.2 265 7 4 5.9 3.2 8500 12.0 53.6 280 9 5 8.8 4.8 | 8.9 48.0 265 5 3 7.1 3.9 8250 13.3 55.9 280 9 5 8.4 4.6 | 9.4 48.9 265 5 3 7.7 4.2 8000 13.9 57.0 280 9 5 9.3 5.1 | 9.9 49.8 260 5 2 6.3 3.5 7750 14.6 58.3 275 10 5 9.7 5.3 | 10.4 50.7 255 4 2 5.9 3.3 7500 15.3 59.5 265 10 5 8.6 4.7 | 10.8 51.4 250 2 1 5.8 3.2 7250 15.9 60.6 270 10 5 7.8 4.3 | 11.2 52.2 235 2 1 5.6 3.1 7000 16.6 61.9 270 10 5 9.8 5.4 | 11.6 52.9 210 1 1 6.3 3.4 6750 17.4 63.3 265 10 5 10.9 6.0 | 12.0 53.6 160 1 1 6.3 3.5 6500 18.1 64.6 260 11 5 10.0 5.5 | 12.4 54.3 135 2 1 5.5 3.0 6250 18.9 66.0 265 10 5 10.0 5.5 | 12.8 55.0 125 4 2 5.4 3.0 6000 19.6 67.3 270 9 5 8.5 4.7 | 13.1 55.6 120 5 2 5.3 2.9 5750 20.2 68.4 260 9 5 11.1 6.1 | 13.5 56.3 125 3 2 7.1 3.9 5500 22.1 71.8 275 8 4 49.6 27.2 | 14.3 57.7 115 5 3 18.4 10.1 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