Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
195 UXUS97 KGJT 161307 SRGGJT Soaring Forecast National Weather Service Grand Junction, Colorado 707 AM MDT Monday, September 16, 2024 This forecast is for Monday, September 16, 2024: If the trigger temperature of 79.3 F/26.3 C is reached...then Thermal Soaring Index....................... Fair Maximum rate of lift........................ 240 ft/min (1.2 m/s) Maximum height of thermals.................. 8593 ft MSL (3754 ft AGL) Forecast maximum temperature................... 79.0 F/26.6 C Time of trigger temperature.................... 1415 MDT Time of overdevelopment........................ None Middle/high clouds during soaring window....... Broken/overcast thin middle Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 5598 ft MSL (759 ft AGL) Thermal soaring outlook for Tuesday 09/17...... Good Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 06:57:11 / 19:20:16 MDT Total possible sunshine........... 12 hr 23 min 5 sec (743 min 5 sec) Altitude of sun at 13:08:44 MDT... 53.05 degrees Upper air data from rawinsonde observation taken on 09/16/2024 at 0600 MDT Freezing level.................. 14397 ft MSL (9558 ft AGL) Convective condensation level... 14651 ft MSL (9812 ft AGL) Lifted condensation level....... 13713 ft MSL (8874 ft AGL) Lifted index.................... +0.2 K index......................... +26.5 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 -61.1 -78.0 230 46 24 0.8 0.4 93.4 200.2 39.0 M M 45000 -56.6 -69.9 240 83 43 5.1 2.8 75.3 167.5 30.6 M M 40000 -49.9 -57.8 240 105 54 7.6 4.2 62.9 145.2 24.5 M M 38000 -45.7 -50.3 235 100 52 6.6 3.6 60.4 140.8 23.4 M M 36000 -42.3 -44.1 230 89 46 2.8 1.5 57.0 134.6 21.6 M M 34000 -41.8 -43.2 230 70 36 2.0 1.1 49.4 120.9 16.7 M M 32000 -38.4 -37.1 225 50 26 8.5 4.6 45.1 113.1 14.0 M M 30000 -33.7 -28.7 220 46 24 7.9 4.3 43.5 110.2 13.1 M M 29000 -31.4 -24.5 220 44 23 6.3 3.5 42.6 108.7 12.6 M M 28000 -29.0 -20.2 215 42 22 8.7 4.8 41.9 107.5 12.3 M M 27000 -26.4 -15.5 215 42 22 8.2 4.5 41.5 106.7 12.1 M M 26000 -24.2 -11.6 220 40 21 7.6 4.2 40.6 105.1 11.5 M M 25000 -22.0 -7.6 215 39 20 6.8 3.7 39.7 103.4 10.9 M M 24000 -19.7 -3.5 215 40 21 7.7 4.2 38.9 102.0 10.4 M M 23000 -17.7 0.1 205 36 18 5.8 3.2 37.8 100.0 9.6 M M 22000 -16.0 3.2 195 31 16 5.8 3.2 36.3 97.4 8.5 M M 21000 -14.2 6.4 185 34 17 6.1 3.3 35.0 95.0 7.4 M M 20000 -12.4 9.7 195 32 16 7.6 4.2 33.7 92.7 6.4 M M 19500 -11.3 11.7 200 30 15 7.5 4.1 33.3 92.0 6.1 M M 19000 -10.2 13.6 200 29 15 7.8 4.3 32.9 91.3 5.8 M M 18500 -9.1 15.6 205 28 15 6.1 3.3 32.5 90.5 5.5 M M 18000 -8.3 17.1 205 30 16 5.8 3.2 31.8 89.3 4.9 M M 17500 -7.0 19.4 205 30 16 6.7 3.7 30.9 87.6 3.9 M M 17000 -6.3 20.7 210 35 18 5.3 2.9 30.3 86.5 3.2 M M 16500 -5.6 21.9 205 33 17 7.5 4.1 29.5 85.2 2.5 M M 16000 -4.3 24.3 210 31 16 8.8 4.8 29.4 84.9 2.3 M M 15500 -2.9 26.8 210 29 15 9.6 5.2 29.3 84.8 2.3 M M 15000 -1.5 29.3 215 26 13 9.5 5.2 29.3 84.8 2.2 M M 14500 -0.1 31.8 210 26 13 9.5 5.2 29.3 84.7 2.2 M M 14000 1.3 34.3 210 25 13 9.5 5.2 29.3 84.7 2.2 M M 13500 2.7 36.9 210 24 12 9.5 5.2 29.2 84.6 2.1 M M 13000 4.1 39.4 220 23 12 9.5 5.2 29.2 84.6 2.1 M M 12500 5.5 41.9 215 24 12 9.5 5.2 29.1 84.5 2.0 M M 12000 6.9 44.4 210 22 11 9.5 5.2 29.1 84.4 2.0 M M 11500 8.3 46.9 210 21 11 9.2 5.0 29.0 84.3 1.9 M M 11000 9.6 49.3 215 19 10 8.2 4.5 28.8 83.9 1.7 M M 10500 10.8 51.4 205 23 12 7.8 4.3 28.6 83.4 1.4 M M 10250 11.4 52.5 205 23 12 9.6 5.3 28.4 83.2 1.3 M M 10000 12.1 53.8 205 22 11 8.6 4.7 28.5 83.3 1.4 M M 9750 12.6 54.7 200 25 13 6.1 3.4 28.2 82.8 1.1 M M 9500 13.0 55.4 200 29 15 6.9 3.8 28.0 82.4 0.8 M M 9250 13.5 56.3 195 32 17 6.7 3.7 27.8 82.0 0.5 M M 9000 13.9 57.0 190 34 17 7.4 4.1 27.5 81.6 0.3 M M 8750 14.5 58.1 190 33 17 7.8 4.3 27.4 81.3 0.1 M M 8500 15.1 59.2 190 31 16 7.7 4.2 27.2 81.0 -0.0 234 1.2 8250 15.7 60.3 185 30 15 7.7 4.2 27.1 80.7 -0.2 209 1.1 8000 16.3 61.3 185 28 15 7.7 4.2 26.9 80.5 -0.3 184 0.9 7750 16.9 62.4 185 27 14 7.7 4.2 26.8 80.2 -0.5 159 0.8 7500 17.4 63.3 180 26 13 7.7 4.2 26.6 79.9 -0.6 135 0.7 7250 18.0 64.4 180 25 13 7.7 4.2 26.5 79.7 -0.8 110 0.6 7000 18.6 65.5 175 22 11 7.8 4.3 26.3 79.4 -0.9 85 0.4 6750 19.2 66.6 175 21 11 7.4 4.1 26.2 79.1 -1.1 60 0.3 6500 19.7 67.5 165 23 12 4.9 2.7 25.9 78.6 -1.3 38 0.2 6250 20.0 68.0 155 24 13 6.4 3.5 25.5 77.9 -1.7 21 0.1 6000 20.5 68.9 155 28 14 7.3 4.0 25.4 77.7 -1.9 M M 5750 20.8 69.4 155 27 14 2.7 1.5 25.0 77.0 -2.3 M M 5500 20.8 69.4 160 24 12 -2.4 -1.3 24.3 75.7 -3.1 M M 5250 20.6 69.1 155 18 9 -2.3 -1.3 23.3 73.9 -4.0 M M 5000 20.6 69.1 150 11 6 3.3 1.8 22.6 72.7 -4.8 M M * * * * * * Numerical weather prediction model forecast data valid * * * * * * 09/16/2024 at 0900 MDT | 09/16/2024 at 1200 MDT | CAPE... +11.5 LI... -0.6 | CAPE... +444.9 LI... -1.7 CINH... -36.9 K Index... +26.5 | CINH... -2.2 K Index... +27.1 | 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 -60.2 -76.4 225 51 26 2.8 1.6 | -59.2 -74.6 220 57 29 2.5 1.4 45000 -55.6 -68.1 230 75 39 3.8 2.1 | -55.4 -67.7 225 79 41 2.8 1.5 40000 -49.7 -57.5 230 105 54 3.6 2.0 | -51.0 -59.8 230 80 41 3.9 2.1 38000 -47.5 -53.5 225 96 49 3.6 2.0 | -48.7 -55.7 225 78 40 3.9 2.1 36000 -45.4 -49.7 225 87 45 3.6 2.0 | -46.3 -51.3 220 77 40 3.9 2.1 34000 -42.8 -45.0 220 77 40 4.6 2.5 | -43.4 -46.1 220 73 38 5.3 2.9 32000 -40.1 -40.2 215 67 34 4.5 2.5 | -40.2 -40.4 215 68 35 5.3 2.9 30000 -36.0 -32.8 215 59 30 8.4 4.6 | -35.9 -32.6 210 64 33 8.4 4.6 29000 -33.5 -28.3 210 56 29 8.4 4.6 | -33.4 -28.1 210 62 32 8.4 4.6 28000 -31.0 -23.8 210 54 28 8.4 4.6 | -30.9 -23.6 210 61 31 8.4 4.6 27000 -28.5 -19.3 210 51 26 7.9 4.3 | -28.4 -19.1 210 59 30 7.9 4.3 26000 -26.2 -15.2 210 49 25 7.9 4.3 | -26.1 -15.0 210 57 29 7.9 4.3 25000 -23.2 -9.8 210 46 24 7.9 4.4 | -23.7 -10.7 210 55 28 7.9 4.3 24000 -20.9 -5.6 210 44 23 7.4 4.1 | -20.8 -5.4 210 52 27 7.5 4.1 23000 -18.7 -1.7 205 43 22 7.4 4.1 | -18.6 -1.5 210 50 26 7.5 4.1 22000 -16.5 2.3 205 42 22 7.6 4.2 | -16.3 2.7 210 47 24 7.6 4.2 21000 -14.6 5.7 205 41 21 6.4 3.5 | -14.3 6.3 205 45 23 6.7 3.7 20000 -12.7 9.1 205 40 21 6.5 3.5 | -12.3 9.9 205 44 23 6.7 3.7 19500 -11.7 10.9 205 40 21 6.5 3.6 | -11.3 11.7 205 43 22 6.7 3.7 19000 -10.8 12.6 205 40 21 6.3 3.5 | -10.3 13.5 205 42 22 6.0 3.3 18500 -9.9 14.2 205 39 20 6.2 3.4 | -9.5 14.9 205 40 21 5.7 3.1 18000 -9.0 15.8 205 38 20 6.3 3.4 | -8.7 16.3 205 39 20 5.8 3.2 17500 -8.1 17.4 205 37 19 6.6 3.6 | -7.8 18.0 205 37 19 6.3 3.5 17000 -7.2 19.0 205 36 19 6.6 3.6 | -7.0 19.4 205 36 18 6.4 3.5 16500 -6.2 20.8 205 35 18 7.2 3.9 | -6.1 21.0 205 34 18 6.7 3.7 16000 -5.1 22.8 205 34 17 7.4 4.1 | -5.1 22.8 205 33 17 6.8 3.7 15500 -4.1 24.6 205 33 17 7.6 4.2 | -4.1 24.6 205 31 16 7.2 4.0 15000 -2.9 26.8 205 32 16 8.0 4.4 | -3.0 26.6 205 30 15 8.1 4.4 14500 -1.8 28.8 205 31 16 8.1 4.4 | -1.8 28.8 200 29 15 8.1 4.4 14000 -0.6 30.9 205 30 15 8.1 4.5 | -0.6 30.9 200 28 14 8.5 4.7 13500 0.6 33.1 205 29 15 8.1 4.4 | 0.6 33.1 200 27 14 8.4 4.6 13000 1.8 35.2 205 28 14 8.5 4.7 | 1.8 35.2 200 26 13 8.8 4.8 12500 3.1 37.6 205 27 14 8.5 4.7 | 3.1 37.6 200 25 13 8.8 4.8 12000 4.4 39.9 205 26 13 8.6 4.7 | 4.3 39.7 195 24 13 8.8 4.8 11500 5.6 42.1 205 25 13 8.7 4.8 | 5.6 42.1 195 24 12 8.8 4.8 11000 6.9 44.4 205 24 12 8.2 4.5 | 6.9 44.4 195 23 12 8.7 4.8 10500 8.1 46.6 205 22 12 7.9 4.4 | 8.1 46.6 195 22 11 8.4 4.6 10250 8.7 47.7 205 22 11 8.7 4.8 | 8.8 47.8 190 22 11 10.4 5.7 10000 9.3 48.7 200 21 11 8.9 4.9 | 9.6 49.3 190 22 11 10.6 5.8 9750 10.0 50.0 200 21 11 8.3 4.5 | 10.3 50.5 190 21 11 9.1 5.0 9500 10.6 51.1 195 20 10 8.1 4.4 | 11.0 51.8 190 21 11 9.1 5.0 9250 11.2 52.2 195 20 10 9.6 5.3 | 11.7 53.1 190 20 10 10.5 5.8 9000 11.9 53.4 195 19 10 9.1 5.0 | 12.5 54.5 185 20 10 10.4 5.7 8750 13.1 55.6 190 18 9 7.7 4.2 | 13.2 55.8 185 19 10 8.8 4.8 8500 13.6 56.5 190 17 9 7.6 4.1 | 14.5 58.1 185 19 10 8.9 4.9 8250 14.2 57.6 185 18 9 7.5 4.1 | 15.2 59.4 185 19 10 9.6 5.3 8000 14.7 58.5 185 17 9 7.4 4.1 | 16.0 60.8 185 18 9 10.5 5.7 7750 15.3 59.5 180 16 8 7.5 4.1 | 16.8 62.2 185 18 9 10.7 5.9 7500 15.8 60.4 180 16 8 5.6 3.1 | 17.5 63.5 185 18 9 9.0 4.9 7250 16.1 61.0 175 17 9 4.4 2.4 | 18.1 64.6 185 18 9 8.2 4.5 7000 16.5 61.7 175 17 9 6.4 3.5 | 18.9 66.0 185 17 9 11.1 6.1 6750 17.0 62.6 170 15 8 6.3 3.4 | 19.7 67.5 185 16 8 12.0 6.6 6500 17.4 63.3 165 14 7 4.3 2.4 | 20.6 69.1 185 16 8 10.9 6.0 6250 17.7 63.9 160 13 7 3.6 2.0 | 21.4 70.5 185 16 8 11.3 6.2 6000 18.0 64.4 155 12 6 5.5 3.0 | 22.2 72.0 185 16 8 7.9 4.3 5750 18.5 65.3 150 9 5 11.4 6.2 | 22.7 72.9 185 14 7 11.9 6.5 5500 19.6 67.3 145 8 4 16.7 9.2 | 25.6 78.1 180 13 6 84.2 46.2 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 09/16/2024 at 1500 MDT | 09/16/2024 at 1800 MDT | CAPE... +229.3 LI... -1.7 | CAPE... +220.4 LI... -1.7 CINH... -10.9 K Index... +28.3 | CINH... -47.0 K Index... +28.5 | 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 -60.0 -76.0 230 50 26 0.9 0.5 | -60.3 -76.5 230 43 22 -0.4 -0.2 45000 -58.1 -72.6 230 70 36 2.7 1.5 | -59.5 -75.1 230 68 35 3.9 2.1 40000 -53.6 -64.5 235 81 42 6.9 3.8 | -53.2 -63.8 235 81 41 5.8 3.2 38000 -49.7 -57.5 235 76 39 6.5 3.5 | -49.9 -57.8 235 77 39 5.6 3.1 36000 -45.9 -50.6 230 72 37 6.5 3.5 | -46.5 -51.7 230 73 37 5.6 3.1 34000 -42.0 -43.6 235 68 35 6.4 3.5 | -42.5 -44.5 225 68 35 7.1 3.9 32000 -38.2 -36.8 240 66 34 6.4 3.5 | -38.2 -36.8 225 62 32 7.1 3.9 30000 -33.9 -29.0 235 59 30 7.5 4.1 | -33.7 -28.7 225 58 30 8.0 4.4 29000 -31.6 -24.9 230 55 28 7.5 4.1 | -31.3 -24.3 225 56 29 8.0 4.4 28000 -29.4 -20.9 225 50 26 7.5 4.1 | -28.9 -20.0 225 54 28 8.0 4.4 27000 -27.1 -16.8 220 49 25 7.8 4.3 | -26.6 -15.9 225 53 27 7.7 4.2 26000 -24.7 -12.5 215 51 26 7.8 4.3 | -24.3 -11.7 225 52 27 7.7 4.2 25000 -21.8 -7.2 210 53 27 7.9 4.3 | -22.0 -7.6 225 51 26 7.7 4.2 24000 -19.7 -3.5 210 52 27 6.9 3.8 | -19.2 -2.6 220 49 25 7.0 3.9 23000 -17.6 0.3 210 52 27 6.9 3.8 | -17.2 1.0 220 49 25 7.1 3.9 22000 -15.5 4.1 210 51 26 7.0 3.9 | -15.1 4.8 215 48 25 7.2 4.0 21000 -13.7 7.3 210 48 25 6.1 3.4 | -13.3 8.1 215 46 24 6.1 3.3 20000 -11.9 10.6 210 45 23 6.2 3.4 | -11.5 11.3 215 43 22 6.1 3.4 19500 -11.0 12.2 210 43 22 6.2 3.4 | -10.6 12.9 215 42 22 6.1 3.4 19000 -10.1 13.8 210 42 21 6.1 3.3 | -9.8 14.4 215 40 21 6.0 3.3 18500 -9.3 15.3 210 40 21 6.0 3.3 | -8.9 16.0 215 38 20 6.0 3.3 18000 -8.4 16.9 210 38 20 6.0 3.3 | -8.1 17.4 215 36 18 6.0 3.3 17500 -7.5 18.5 210 37 19 7.0 3.8 | -7.2 19.0 215 34 18 6.4 3.5 17000 -6.5 20.3 210 35 18 7.0 3.8 | -6.3 20.7 215 32 17 6.3 3.5 16500 -5.5 22.1 205 34 18 7.3 4.0 | -5.3 22.5 215 31 16 7.0 3.8 16000 -4.4 24.1 205 33 17 7.5 4.1 | -4.3 24.3 215 30 15 7.3 4.0 15500 -3.3 26.1 205 32 17 7.5 4.1 | -3.2 26.2 215 29 15 7.4 4.1 15000 -2.2 28.0 205 31 16 7.6 4.1 | -2.1 28.2 215 28 15 7.7 4.3 14500 -1.2 29.8 205 30 16 7.6 4.2 | -1.0 30.2 210 28 14 7.7 4.2 14000 -0.0 32.0 205 29 15 8.2 4.5 | 0.2 32.4 210 27 14 7.9 4.3 13500 1.1 34.0 205 28 15 8.1 4.5 | 1.3 34.3 205 26 14 7.9 4.3 13000 2.4 36.3 200 28 14 8.8 4.8 | 2.5 36.5 205 26 13 8.4 4.6 12500 3.6 38.5 200 27 14 8.8 4.8 | 3.7 38.7 205 25 13 8.4 4.6 12000 5.0 41.0 200 26 14 9.2 5.1 | 4.9 40.8 200 25 13 8.9 4.9 11500 6.3 43.3 200 26 13 9.3 5.1 | 6.3 43.3 200 25 13 9.0 4.9 11000 7.7 45.9 200 25 13 8.5 4.7 | 7.5 45.5 195 25 13 8.1 4.5 10500 8.9 48.0 200 25 13 8.2 4.5 | 8.7 47.7 195 24 12 7.5 4.1 10250 9.6 49.3 200 25 13 11.2 6.1 | 9.3 48.7 195 24 12 10.5 5.8 10000 10.5 50.9 200 25 13 11.2 6.2 | 10.2 50.4 195 24 12 10.9 6.0 9750 11.2 52.2 200 24 13 8.8 4.9 | 10.8 51.4 195 24 12 8.5 4.6 9500 11.9 53.4 200 24 12 9.5 5.2 | 11.5 52.7 195 24 12 9.3 5.1 9250 12.6 54.7 200 24 12 9.3 5.1 | 12.1 53.8 190 23 12 8.5 4.6 9000 14.0 57.2 200 23 12 9.4 5.2 | 12.7 54.9 190 23 12 8.6 4.7 8750 14.7 58.5 200 23 12 9.4 5.2 | 14.1 57.4 190 22 11 9.2 5.0 8500 15.4 59.7 200 23 12 9.4 5.2 | 14.8 58.6 190 21 11 9.2 5.1 8250 16.1 61.0 200 23 12 9.6 5.3 | 15.5 59.9 190 21 11 8.8 4.8 8000 16.8 62.2 195 22 11 9.6 5.3 | 16.1 61.0 190 20 10 8.4 4.6 7750 17.5 63.5 195 21 11 9.8 5.4 | 16.7 62.1 190 19 10 8.8 4.8 7500 18.2 64.8 195 21 11 9.0 4.9 | 17.3 63.1 190 18 9 7.4 4.0 7250 18.8 65.8 195 21 11 8.5 4.7 | 17.8 64.0 190 17 9 6.2 3.4 7000 19.5 67.1 195 21 11 9.7 5.3 | 18.3 64.9 190 16 8 7.8 4.3 6750 20.3 68.5 195 19 10 10.3 5.7 | 18.9 66.0 195 14 7 8.5 4.6 6500 21.0 69.8 195 18 9 10.7 5.9 | 19.5 67.1 195 12 6 8.6 4.7 6250 21.9 71.4 195 18 9 11.7 6.4 | 20.1 68.2 190 12 6 9.1 5.0 6000 22.7 72.9 195 18 9 7.9 4.3 | 20.8 69.4 190 12 6 7.3 4.0 5750 23.1 73.6 195 16 8 9.4 5.1 | 21.2 70.2 195 9 5 7.4 4.0 5500 25.4 77.7 195 14 7 68.7 37.7 | 22.4 72.3 195 7 4 31.9 17.5 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