Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
718 UXUS97 KBOU 200122 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1921 MDT Sunday, May 19, 2024 This forecast is for Monday, May 20, 2024: If the trigger temperature of 62.2 F/16.8 C is reached...then Thermal Soaring Index....................... Good Maximum rate of lift........................ 541 ft/min (2.7 m/s) Maximum height of thermals.................. 13169 ft MSL (7900 ft AGL) Forecast maximum temperature................... 75.0 F/24.3 C Time of trigger temperature.................... 1015 MDT Time of overdevelopment........................ 1400 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 11202 ft MSL (5933 ft AGL) Thermal soaring outlook for Tuesday 05/21...... Good Wave Soaring Index............................. Poor Wave Soaring Index trend (to 1800 MDT)......... No change Height of stable layer (12-18K ft MSL)......... None Weak PVA/NVA (through 1800 MDT)................ Weak PVA Potential height of wave....................... 39658 ft MSL (34389 ft AGL) Wave soaring outlook for Tuesday 05/21......... Good Remarks... Sunrise/Sunset.................... 05:39:53 / 20:12:16 MDT Total possible sunshine........... 14 hr 32 min 23 sec (872 min 23 sec) Altitude of sun at 12:56:05 MDT... 70.41 degrees Upper air data from numerical model forecast valid on 05/20/2024 at 0600 MDT Freezing level.................. 13139 ft MSL (7870 ft AGL) Convective condensation level... 13470 ft MSL (8201 ft AGL) Lifted condensation level....... 13589 ft MSL (8320 ft AGL) Lifted index.................... -3.0 K index......................... +20.5 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 -55.1 -67.2 250 54 28 1.2 0.7 M M M M M 45000 -53.6 -64.5 255 64 33 -0.5 -0.3 M M M M M 40000 -54.4 -65.9 260 83 43 -0.9 -0.5 M M M M M 38000 -52.3 -62.1 260 81 42 4.3 2.4 M M M M M 36000 -49.8 -57.6 260 77 39 4.3 2.4 M M M M M 34000 -46.7 -52.1 255 69 35 6.1 3.3 M M M M M 32000 -43.1 -45.6 250 56 29 6.1 3.3 M M M M M 30000 -39.2 -38.6 240 47 24 7.4 4.0 37.2 99.0 10.1 M M 29000 -37.0 -34.6 240 45 23 7.4 4.0 36.2 97.2 9.4 M M 28000 -34.8 -30.6 240 43 22 7.4 4.0 35.3 95.6 8.9 M M 27000 -31.9 -25.4 240 41 21 8.0 4.4 34.4 93.9 8.2 M M 26000 -29.5 -21.1 240 41 21 8.0 4.4 33.6 92.6 7.7 M M 25000 -27.1 -16.8 245 41 21 8.0 4.4 33.0 91.5 7.3 M M 24000 -24.8 -12.6 245 41 21 7.5 4.1 32.4 90.3 6.9 M M 23000 -22.5 -8.5 245 40 21 7.5 4.1 31.5 88.7 6.3 M M 22000 -20.3 -4.5 245 39 20 7.5 4.1 30.8 87.4 5.7 M M 21000 -18.2 -0.8 245 38 20 6.2 3.4 29.8 85.7 4.9 M M 20000 -16.3 2.7 245 37 19 6.3 3.5 28.5 83.4 3.9 M M 19500 -15.4 4.3 240 36 19 6.4 3.5 28.0 82.3 3.4 M M 19000 -14.5 5.9 240 36 18 6.4 3.5 27.4 81.4 2.9 M M 18500 -13.5 7.7 240 35 18 6.8 3.7 26.9 80.4 2.4 M M 18000 -12.6 9.3 245 34 18 6.9 3.8 26.4 79.5 1.9 M M 17500 -11.6 11.1 245 34 17 7.4 4.0 25.9 78.6 1.5 M M 17000 -10.5 13.1 245 32 17 7.8 4.3 25.5 78.0 1.1 M M 16500 -9.3 15.3 245 31 16 7.9 4.3 25.2 77.4 0.8 M M 16000 -8.0 17.6 245 29 15 9.4 5.2 25.0 77.1 0.6 M M 15500 -6.7 19.9 240 28 14 9.3 5.1 25.0 76.9 0.6 M M 15000 -5.3 22.5 240 27 14 9.4 5.1 24.9 76.8 0.5 M M 14500 -3.9 25.0 235 26 13 9.4 5.1 24.8 76.7 0.4 M M 14000 -2.5 27.5 235 25 13 8.9 4.9 24.8 76.6 0.4 M M 13500 -1.2 29.8 230 24 12 8.5 4.7 24.6 76.2 0.2 M M 13000 0.5 32.9 220 23 12 5.5 3.0 24.1 75.4 -0.3 516 2.6 12500 1.2 34.2 210 22 11 5.6 3.1 23.4 74.1 -1.0 478 2.4 12000 2.0 35.6 205 20 10 4.6 2.5 22.7 72.8 -1.7 442 2.2 11500 2.5 36.5 195 18 9 4.5 2.5 21.8 71.3 -2.6 409 2.1 11000 3.1 37.6 185 15 8 4.0 2.2 21.0 69.7 -3.5 377 1.9 10500 3.6 38.5 185 11 6 4.5 2.5 20.0 68.1 -4.5 347 1.8 10250 3.9 39.0 180 9 5 1.7 0.9 19.6 67.2 -5.0 332 1.7 10000 3.9 39.0 180 9 5 2.2 1.2 18.9 65.9 -5.7 323 1.6 9750 4.2 39.6 180 7 4 5.2 2.8 18.4 65.2 -6.1 307 1.6 9500 4.6 40.3 180 6 3 4.7 2.6 18.0 64.5 -6.5 290 1.5 9250 4.9 40.8 180 4 2 3.5 1.9 17.6 63.8 -7.0 273 1.4 9000 5.1 41.2 175 3 2 3.5 1.9 17.1 62.8 -7.5 260 1.3 8750 5.4 41.7 165 3 1 5.5 3.0 16.7 62.1 -7.9 242 1.2 8500 5.8 42.4 145 2 1 6.1 3.4 16.4 61.5 -8.2 222 1.1 8250 6.2 43.2 110 2 1 3.7 2.0 16.1 61.0 -8.6 203 1.0 8000 6.4 43.5 075 3 1 1.6 0.9 15.5 59.9 -9.2 192 1.0 7750 6.5 43.7 060 4 2 3.6 2.0 14.9 58.9 -9.8 179 0.9 7500 6.8 44.2 050 5 3 4.1 2.2 14.5 58.1 -10.3 164 0.8 7250 7.1 44.8 045 6 3 3.6 2.0 14.0 57.3 -10.7 148 0.8 7000 7.4 45.3 035 7 4 3.2 1.8 13.6 56.4 -11.2 132 0.7 6750 7.6 45.7 025 8 4 5.0 2.7 13.1 55.6 -11.7 116 0.6 6500 8.1 46.6 020 9 5 5.7 3.1 12.8 55.1 -12.0 96 0.5 6250 8.4 47.1 010 9 4 4.7 2.6 12.5 54.4 -12.4 78 0.4 6000 8.8 47.8 360 9 5 4.8 2.6 12.1 53.8 -12.8 60 0.3 5750 9.2 48.6 355 9 5 5.4 2.9 11.7 53.1 -13.2 41 0.2 5500 9.5 49.1 345 8 4 4.6 2.5 11.4 52.5 -13.6 23 0.1 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 05/20/2024 at 0900 MDT | 05/20/2024 at 1200 MDT | CAPE... 0.0 LI... +1.1 | CAPE... +64.6 LI... -0.5 CINH... -0.9 K Index... +20.2 | CINH... -81.5 K Index... +18.4 | 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 -55.9 -68.6 245 54 28 1.1 0.6 | -56.0 -68.8 245 52 27 0.7 0.4 45000 -54.5 -66.1 245 62 32 0.2 0.1 | -55.1 -67.2 240 63 33 0.5 0.3 40000 -54.2 -65.6 255 78 40 -0.3 -0.1 | -54.3 -65.7 255 82 42 0.1 0.0 38000 -52.0 -61.6 260 82 42 4.4 2.4 | -52.0 -61.6 255 89 46 4.4 2.4 36000 -49.4 -56.9 260 85 44 4.4 2.4 | -49.3 -56.7 250 95 49 4.4 2.4 34000 -46.2 -51.2 260 84 43 6.3 3.5 | -46.2 -51.2 250 96 49 6.1 3.4 32000 -42.5 -44.5 260 78 40 6.3 3.5 | -42.6 -44.7 250 90 46 6.1 3.4 30000 -38.5 -37.3 255 69 36 7.0 3.9 | -38.6 -37.5 250 81 42 7.3 4.0 29000 -36.4 -33.5 255 63 32 7.0 3.9 | -36.5 -33.7 250 75 38 7.3 4.0 28000 -33.8 -28.8 255 55 28 7.0 3.9 | -34.3 -29.7 250 68 35 7.3 4.0 27000 -31.7 -25.1 250 50 26 7.3 4.0 | -31.6 -24.9 250 61 32 7.3 4.0 26000 -29.5 -21.1 250 48 25 7.3 4.0 | -29.4 -20.9 245 56 29 7.4 4.0 25000 -27.3 -17.1 245 45 23 7.3 4.0 | -27.2 -17.0 245 52 27 7.4 4.0 24000 -25.1 -13.2 245 44 22 7.9 4.4 | -24.9 -12.8 240 48 25 8.2 4.5 23000 -22.7 -8.9 240 43 22 7.9 4.3 | -22.5 -8.5 240 47 24 8.2 4.5 22000 -20.4 -4.7 240 42 22 7.9 4.3 | -20.1 -4.2 240 46 24 8.2 4.5 21000 -18.1 -0.6 240 42 21 7.4 4.1 | -17.7 0.1 240 45 23 7.2 3.9 20000 -15.9 3.4 245 41 21 7.4 4.1 | -15.6 3.9 240 43 22 7.2 3.9 19500 -14.8 5.4 245 41 21 7.4 4.1 | -14.5 5.9 240 42 21 7.2 4.0 19000 -13.7 7.3 245 41 21 7.5 4.1 | -13.5 7.7 240 41 21 7.2 4.0 18500 -12.6 9.3 245 40 21 6.4 3.5 | -12.4 9.7 240 40 20 6.9 3.8 18000 -11.7 10.9 240 39 20 6.5 3.6 | -11.4 11.5 240 39 20 6.9 3.8 17500 -10.7 12.7 240 38 19 6.4 3.5 | -10.4 13.3 235 38 19 7.1 3.9 17000 -9.8 14.4 240 35 18 6.3 3.5 | -9.4 15.1 235 37 19 7.2 4.0 16500 -8.9 16.0 240 33 17 6.4 3.5 | -8.3 17.1 235 36 18 7.3 4.0 16000 -7.9 17.8 235 31 16 7.6 4.2 | -7.2 19.0 235 35 18 8.2 4.5 15500 -6.9 19.6 235 29 15 7.5 4.1 | -6.0 21.2 230 34 17 8.2 4.5 15000 -5.7 21.7 230 27 14 8.9 4.9 | -4.8 23.4 230 33 17 8.3 4.6 14500 -4.4 24.1 230 27 14 9.1 5.0 | -3.5 25.7 225 32 16 8.4 4.6 14000 -2.3 27.9 230 27 14 9.2 5.0 | -2.3 27.9 225 31 16 8.4 4.6 13500 -1.0 30.2 225 27 14 9.2 5.0 | -0.5 31.1 220 29 15 8.5 4.7 13000 0.3 32.5 225 27 14 8.7 4.8 | 0.8 33.4 220 28 15 8.7 4.8 12500 1.6 34.9 220 27 14 8.8 4.8 | 2.1 35.8 215 27 14 8.7 4.8 12000 2.8 37.0 220 27 14 7.0 3.9 | 3.3 37.9 215 26 13 8.6 4.7 11500 3.7 38.7 215 26 13 6.9 3.8 | 4.6 40.3 210 25 13 8.7 4.8 11000 4.6 40.3 210 25 13 4.2 2.3 | 5.7 42.3 210 24 12 6.6 3.6 10500 5.0 41.0 205 23 12 3.9 2.2 | 6.6 43.9 205 23 12 5.2 2.8 10250 5.3 41.5 200 22 11 2.3 1.3 | 7.0 44.6 205 22 12 10.1 5.5 10000 5.3 41.5 200 22 11 0.5 0.3 | 7.9 46.2 200 22 11 9.4 5.2 9750 5.3 41.5 200 20 10 0.8 0.4 | 8.2 46.8 195 21 11 3.5 1.9 9500 5.4 41.7 200 18 9 0.9 0.5 | 8.5 47.3 195 20 10 6.3 3.4 9250 5.4 41.7 195 16 8 0.3 0.2 | 8.9 48.0 190 19 10 1.4 0.8 9000 5.3 41.5 195 14 7 -0.9 -0.5 | 8.7 47.7 190 18 9 -0.6 -0.3 8750 5.2 41.4 195 12 6 -1.1 -0.6 | 8.8 47.8 185 15 8 2.3 1.3 8500 5.1 41.2 195 9 5 -1.3 -0.7 | 8.9 48.0 180 13 7 1.6 0.9 8250 5.0 41.0 195 7 3 -0.5 -0.3 | 9.0 48.2 170 11 5 1.8 1.0 8000 5.0 41.0 185 5 3 1.3 0.7 | 9.2 48.6 160 9 5 4.8 2.6 7750 5.2 41.4 170 4 2 4.8 2.6 | 9.7 49.5 150 8 4 9.3 5.1 7500 5.6 42.1 150 3 2 6.5 3.6 | 10.5 50.9 145 8 4 10.4 5.7 7250 6.1 43.0 125 3 1 5.3 2.9 | 11.2 52.2 140 7 4 7.8 4.3 7000 6.4 43.5 105 3 1 4.5 2.5 | 11.7 53.1 140 7 4 6.5 3.6 6750 6.9 44.4 090 3 1 9.0 5.0 | 12.3 54.1 135 7 4 11.9 6.5 6500 7.7 45.9 070 3 1 11.1 6.1 | 13.3 55.9 130 7 4 13.2 7.2 6250 8.4 47.1 070 3 1 9.0 4.9 | 14.2 57.6 130 7 3 9.9 5.4 6000 9.1 48.4 065 3 2 8.6 4.7 | 14.9 58.8 125 6 3 9.1 5.0 5750 9.8 49.6 065 3 2 11.6 6.4 | 15.6 60.1 125 6 3 12.2 6.7 5500 11.0 51.8 060 3 2 20.0 11.0 | 16.9 62.4 120 6 3 23.8 13.0 05/20/2024 at 1500 MDT | 05/20/2024 at 1800 MDT | CAPE... +222.8 LI... -2.0 | CAPE... +143.2 LI... -1.8 CINH... -76.8 K Index... +27.6 | CINH... -29.6 K Index... +24.3 | 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 -55.3 -67.5 240 51 26 0.9 0.5 | -55.0 -67.0 245 47 24 2.1 1.1 45000 -54.1 -65.4 240 71 37 -0.1 -0.1 | -52.4 -62.3 240 65 33 -0.9 -0.5 40000 -54.3 -65.7 250 87 45 -0.5 -0.3 | -54.0 -65.2 240 83 43 -1.2 -0.7 38000 -52.2 -62.0 250 94 48 4.3 2.4 | -52.3 -62.1 240 91 47 3.8 2.1 36000 -49.6 -57.3 250 100 52 4.3 2.4 | -50.1 -58.2 240 100 51 3.8 2.1 34000 -46.5 -51.7 250 103 53 6.2 3.4 | -47.2 -53.0 240 101 52 6.6 3.6 32000 -42.8 -45.0 250 101 52 6.2 3.4 | -43.2 -45.8 240 93 48 6.6 3.6 30000 -39.0 -38.2 250 92 48 6.7 3.7 | -39.1 -38.4 240 84 43 7.4 4.1 29000 -37.0 -34.6 250 83 43 6.7 3.7 | -36.9 -34.4 240 79 41 7.4 4.1 28000 -34.9 -30.8 250 74 38 6.7 3.7 | -34.7 -30.5 240 74 38 7.4 4.1 27000 -32.9 -27.2 250 66 34 7.8 4.3 | -32.5 -26.5 240 69 35 7.1 3.9 26000 -30.6 -23.1 245 60 31 7.8 4.3 | -29.8 -21.6 240 58 30 7.1 3.9 25000 -27.7 -17.9 240 52 27 7.8 4.3 | -27.7 -17.9 240 50 26 7.1 3.9 24000 -25.3 -13.5 240 47 24 8.7 4.8 | -25.6 -14.1 235 44 22 7.7 4.2 23000 -22.7 -8.9 235 42 22 8.6 4.7 | -23.3 -9.9 235 42 22 7.7 4.2 22000 -20.2 -4.4 230 39 20 8.6 4.7 | -21.0 -5.8 235 41 21 7.7 4.2 21000 -17.8 -0.0 230 36 19 7.0 3.9 | -18.7 -1.7 230 40 20 8.2 4.5 20000 -15.7 3.7 230 37 19 7.1 3.9 | -16.3 2.7 225 39 20 8.2 4.5 19500 -14.7 5.5 235 37 19 7.1 3.9 | -15.1 4.8 225 38 20 8.2 4.5 19000 -13.7 7.3 235 37 19 7.0 3.9 | -13.9 7.0 220 38 20 8.1 4.5 18500 -12.5 9.5 235 37 19 8.3 4.5 | -12.6 9.3 220 38 19 9.5 5.2 18000 -11.4 11.5 230 36 19 8.2 4.5 | -11.2 11.8 220 37 19 9.5 5.2 17500 -10.2 13.6 230 35 18 8.6 4.7 | -9.8 14.4 215 37 19 9.4 5.1 17000 -8.8 16.2 225 34 18 9.0 4.9 | -8.4 16.9 215 37 19 9.2 5.1 16500 -7.5 18.5 220 33 17 9.0 4.9 | -7.1 19.2 215 36 19 9.2 5.1 16000 -6.2 20.8 220 33 17 9.1 5.0 | -5.7 21.7 215 36 18 9.3 5.1 15500 -4.9 23.2 215 32 16 9.1 5.0 | -4.3 24.3 215 35 18 9.3 5.1 15000 -3.5 25.7 215 31 16 8.9 4.9 | -2.9 26.8 215 34 17 9.6 5.3 14500 -2.2 28.0 210 30 16 8.9 4.9 | -1.5 29.3 215 33 17 9.6 5.3 14000 -0.9 30.4 210 30 15 9.0 5.0 | -0.0 32.0 215 32 16 9.4 5.1 13500 0.4 32.7 205 29 15 9.2 5.0 | 1.3 34.3 210 30 16 9.0 4.9 13000 1.8 35.2 205 29 15 9.2 5.0 | 2.6 36.7 210 29 15 8.9 4.9 12500 3.1 37.6 200 28 15 9.1 5.0 | 3.8 38.8 210 27 14 8.4 4.6 12000 4.5 40.1 200 28 14 9.0 5.0 | 5.1 41.2 205 25 13 8.5 4.6 11500 5.7 42.3 200 27 14 8.7 4.8 | 6.2 43.2 205 22 11 7.0 3.8 11000 7.5 45.5 195 25 13 5.9 3.3 | 7.6 45.7 205 17 9 4.2 2.3 10500 8.2 46.8 195 23 12 3.9 2.1 | 7.8 46.0 205 13 7 1.3 0.7 10250 8.5 47.3 190 22 11 8.9 4.9 | 7.9 46.2 205 11 6 5.4 2.9 10000 9.3 48.7 190 21 11 8.0 4.4 | 8.4 47.1 210 8 4 7.1 3.9 9750 9.5 49.1 190 19 10 1.9 1.0 | 8.7 47.7 210 6 3 3.5 1.9 9500 9.7 49.5 190 17 9 4.2 2.3 | 9.1 48.4 215 5 2 6.0 3.3 9250 9.9 49.8 190 15 8 1.1 0.6 | 9.4 48.9 230 3 2 -0.1 -0.0 9000 10.0 50.0 195 13 7 4.4 2.4 | 9.2 48.6 255 2 1 0.9 0.5 8750 10.6 51.1 190 12 6 9.2 5.0 | 9.6 49.3 300 2 1 7.2 4.0 8500 11.2 52.2 190 10 5 8.7 4.8 | 10.1 50.2 335 3 2 6.2 3.4 8250 11.8 53.2 190 9 5 6.0 3.3 | 10.5 50.9 345 4 2 4.0 2.2 8000 12.1 53.8 190 8 4 6.3 3.5 | 10.6 51.1 350 6 3 1.6 0.9 7750 12.8 55.0 190 7 4 11.2 6.2 | 10.9 51.6 355 7 4 5.4 3.0 7500 13.7 56.7 190 7 4 12.7 6.9 | 11.4 52.5 355 9 4 7.8 4.3 7250 14.6 58.3 185 7 4 9.1 5.0 | 11.9 53.4 360 10 5 5.7 3.1 7000 15.1 59.2 185 7 3 6.5 3.5 | 12.2 54.0 355 11 6 4.3 2.4 6750 15.8 60.4 185 6 3 11.3 6.2 | 12.7 54.9 355 13 7 8.5 4.7 6500 16.7 62.1 185 6 3 12.8 7.0 | 13.4 56.1 355 14 7 11.1 6.1 6250 17.5 63.5 180 5 3 9.8 5.4 | 14.1 57.4 355 15 7 8.5 4.7 6000 18.2 64.8 180 5 3 8.2 4.5 | 14.7 58.5 355 14 7 7.0 3.8 5750 18.9 66.0 175 4 2 11.8 6.5 | 15.3 59.5 360 14 7 9.5 5.2 5500 20.0 68.0 140 3 1 19.2 10.6 | 16.1 61.0 360 12 6 13.8 7.6 ________________________________________________________________________________ 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 near the old Stapleton Airport site in Denver, Colorado at North Latitude: 39 deg 46 min 5.016 sec West Longitude: 104 deg 52 min 9.984 sec Elevation: 5285 feet (1611 meters) and may not be representative of other areas along the Front Range of the Colorado Rocky Mountains. 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