![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
670 UXUS97 KBOU 181320 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0718 MDT Tuesday, June 18, 2024 This forecast is for Tuesday, June 18, 2024: If the trigger temperature of 73.0 F/22.8 C is reached...then Thermal Soaring Index....................... Fair Maximum rate of lift........................ 306 ft/min (1.6 m/s) Maximum height of thermals.................. 9908 ft MSL (4638 ft AGL) Forecast maximum temperature................... 76.0 F/24.9 C Time of trigger temperature.................... 1245 MDT Time of overdevelopment........................ 2000 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 8783 ft MSL (3513 ft AGL) Thermal soaring outlook for Wednesday 06/19.... Poor 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)................ Neither Potential height of wave....................... 16827 ft MSL (11557 ft AGL) Wave soaring outlook for Wednesday 06/19....... Good Remarks... Sunrise/Sunset.................... 05:31:11 / 20:30:26 MDT Total possible sunshine........... 14 hr 59 min 15 sec (899 min 15 sec) Altitude of sun at 13:00:49 MDT... 73.65 degrees Upper air data from numerical model forecast valid on 06/18/2024 at 0600 MDT Freezing level.................. 15264 ft MSL (9994 ft AGL) Convective condensation level... 17428 ft MSL (12158 ft AGL) Lifted condensation level....... 15116 ft MSL (9846 ft AGL) Lifted index.................... +4.0 K index......................... +16.1 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 -57.3 -71.1 230 51 26 3.9 2.1 M M M M M 45000 -53.0 -63.4 230 67 35 -1.5 -0.8 M M M M M 40000 -55.0 -67.0 220 59 30 4.8 2.6 M M M M M 38000 -50.9 -59.6 220 59 30 6.9 3.8 M M M M M 36000 -46.8 -52.2 215 59 30 6.9 3.8 M M M M M 34000 -42.5 -44.5 215 60 31 7.4 4.1 M M M M M 32000 -38.0 -36.4 215 60 31 7.4 4.1 M M M M M 30000 -33.2 -27.8 215 60 31 8.7 4.8 43.3 110.0 14.3 M M 29000 -30.6 -23.1 215 60 31 8.7 4.8 42.9 109.2 14.1 M M 28000 -27.4 -17.3 215 59 31 8.9 4.9 42.5 108.6 14.0 M M 27000 -25.1 -13.2 220 58 30 7.3 4.0 41.7 107.0 13.5 M M 26000 -22.9 -9.2 220 57 29 7.3 4.0 40.7 105.3 12.8 M M 25000 -20.8 -5.4 225 56 29 7.3 4.0 39.9 103.8 12.3 M M 24000 -18.7 -1.7 225 54 28 6.6 3.6 38.9 102.0 11.6 M M 23000 -16.7 1.9 225 52 27 6.6 3.6 37.7 99.8 10.7 M M 22000 -14.7 5.5 225 49 25 6.6 3.6 36.6 97.9 9.9 M M 21000 -12.8 9.0 220 46 24 6.8 3.7 35.5 95.9 9.1 M M 20000 -10.7 12.7 215 41 21 6.8 3.7 34.4 94.0 8.3 M M 19500 -9.7 14.5 210 39 20 6.8 3.7 33.9 93.1 7.9 M M 19000 -8.7 16.3 205 37 19 6.8 3.7 33.5 92.2 7.5 M M 18500 -7.9 17.8 205 34 18 5.2 2.8 32.8 91.0 6.9 M M 18000 -7.1 19.2 200 31 16 5.4 3.0 32.0 89.6 6.2 M M 17500 -6.4 20.5 200 28 14 7.7 4.2 31.4 88.4 5.6 M M 17000 -5.0 23.0 205 27 14 9.0 4.9 31.2 88.2 5.5 M M 16500 -3.6 25.5 210 26 13 9.1 5.0 31.1 88.0 5.5 M M 16000 -2.3 27.9 215 25 13 9.1 5.0 31.0 87.8 5.4 M M 15500 -0.9 30.4 220 24 12 9.1 5.0 30.9 87.6 5.3 M M 15000 0.4 32.7 225 24 12 8.8 4.8 30.8 87.4 5.2 M M 14500 1.7 35.1 230 23 12 8.8 4.8 30.6 87.1 5.1 M M 14000 3.1 37.6 235 23 12 8.6 4.7 30.5 86.8 5.0 M M 13500 4.9 40.8 240 22 12 8.4 4.6 30.1 86.2 4.7 M M 13000 6.2 43.2 240 22 11 7.9 4.4 29.9 85.8 4.5 M M 12500 7.3 45.1 235 19 10 7.9 4.3 29.6 85.2 4.2 M M 12000 8.4 47.1 230 17 9 5.7 3.1 29.2 84.6 3.9 M M 11500 9.1 48.4 225 14 7 4.7 2.6 28.4 83.1 3.1 M M 11000 9.7 49.5 210 10 5 3.6 2.0 27.6 81.6 2.3 M M 10500 10.0 50.0 185 7 4 2.6 1.4 26.5 79.6 1.2 M M 10250 10.2 50.4 165 7 4 3.8 2.1 25.9 78.6 0.6 M M 10000 10.4 50.7 135 8 4 3.1 1.7 25.5 77.8 0.1 M M 9750 10.5 50.9 125 8 4 1.4 0.8 24.8 76.7 -0.5 297 1.5 9500 10.6 51.1 120 9 5 1.7 0.9 24.2 75.6 -1.2 286 1.5 9250 10.7 51.3 115 9 5 2.2 1.2 23.6 74.4 -1.8 275 1.4 9000 10.8 51.4 115 8 4 -0.1 -0.1 23.0 73.3 -2.4 264 1.3 8750 10.7 51.3 120 4 2 -2.5 -1.4 22.0 71.7 -3.2 260 1.3 8500 10.6 51.1 180 1 1 -1.6 -0.9 21.1 70.0 -4.1 256 1.3 8250 10.5 50.9 265 4 2 -2.7 -1.5 20.2 68.4 -4.9 252 1.3 8000 10.3 50.5 290 5 3 -4.1 -2.2 19.2 66.6 -5.9 252 1.3 7750 10.0 50.0 330 5 3 -2.3 -1.3 18.2 64.7 -6.9 252 1.3 7500 9.9 49.8 005 6 3 -1.7 -0.9 17.3 63.2 -7.8 248 1.3 7250 9.8 49.6 020 9 5 0.6 0.3 16.5 61.7 -8.6 243 1.2 7000 10.0 50.0 030 11 6 4.3 2.4 16.0 60.7 -9.1 229 1.2 6750 10.4 50.7 035 12 6 5.8 3.2 15.6 60.1 -9.5 211 1.1 6500 10.9 51.6 040 13 7 6.9 3.8 15.4 59.6 -9.8 189 1.0 6250 11.4 52.5 045 13 7 7.7 4.2 15.1 59.3 -10.0 166 0.8 6000 12.0 53.6 050 13 6 8.3 4.5 15.0 59.1 -10.2 141 0.7 5750 12.6 54.7 055 12 6 8.9 4.9 14.9 58.9 -10.4 116 0.6 5500 13.3 55.9 065 9 5 9.6 5.2 14.9 58.8 -10.4 88 0.4 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 06/18/2024 at 0900 MDT | 06/18/2024 at 1200 MDT | CAPE... 0.0 LI... +2.8 | CAPE... 0.0 LI... +3.3 CINH... 0.0 K Index... +16.0 | CINH... 0.0 K Index... +13.2 | 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 -57.6 -71.7 225 58 30 3.4 1.9 | -57.2 -71.0 220 59 30 2.5 1.4 45000 -53.9 -65.0 225 71 36 -1.2 -0.7 | -54.1 -65.4 225 77 40 0.1 0.1 40000 -55.6 -68.1 220 77 39 4.3 2.3 | -53.9 -65.0 225 78 40 3.4 1.9 38000 -51.6 -60.9 215 74 38 6.7 3.7 | -50.5 -58.9 225 77 40 5.7 3.1 36000 -47.5 -53.5 215 71 37 6.7 3.7 | -47.1 -52.8 220 76 39 5.7 3.1 34000 -43.1 -45.6 215 69 36 7.7 4.2 | -43.2 -45.8 220 75 39 7.2 4.0 32000 -38.5 -37.3 215 68 35 7.7 4.2 | -38.8 -37.8 220 74 38 7.2 4.0 30000 -33.9 -29.0 215 66 34 7.9 4.4 | -34.4 -29.9 220 70 36 7.6 4.2 29000 -31.5 -24.7 215 65 33 8.0 4.4 | -31.5 -24.7 225 67 35 7.6 4.2 28000 -28.5 -19.3 220 64 33 8.0 4.4 | -29.2 -20.6 225 65 34 7.6 4.2 27000 -26.2 -15.2 220 61 32 7.7 4.2 | -26.8 -16.2 225 64 33 8.1 4.5 26000 -23.9 -11.0 220 59 30 7.7 4.2 | -24.4 -11.9 225 63 32 8.1 4.5 25000 -21.6 -6.9 220 56 29 7.7 4.2 | -21.9 -7.4 225 62 32 8.1 4.4 24000 -19.5 -3.1 225 53 28 6.1 3.4 | -19.7 -3.5 225 60 31 6.8 3.7 23000 -17.7 0.1 225 50 26 6.1 3.4 | -17.6 0.3 230 59 30 6.8 3.7 22000 -15.9 3.4 225 47 24 6.2 3.4 | -15.6 3.9 230 57 30 6.8 3.7 21000 -13.9 7.0 225 45 23 7.4 4.1 | -13.6 7.5 230 55 29 6.5 3.6 20000 -11.7 10.9 225 44 23 7.4 4.1 | -11.7 10.9 235 53 27 6.6 3.6 19500 -10.6 12.9 225 43 22 7.4 4.1 | -10.7 12.7 235 52 27 6.6 3.6 19000 -9.4 15.1 225 43 22 7.5 4.1 | -9.8 14.4 235 51 26 6.6 3.6 18500 -8.2 17.2 225 42 21 8.3 4.6 | -8.9 16.0 235 49 25 5.2 2.9 18000 -7.0 19.4 220 40 21 8.3 4.5 | -8.1 17.4 235 47 24 5.4 3.0 17500 -5.8 21.6 220 39 20 7.6 4.1 | -7.3 18.9 235 45 23 6.8 3.7 17000 -4.8 23.4 215 38 19 7.3 4.0 | -6.2 20.8 235 44 22 7.6 4.2 16500 -3.7 25.3 215 36 19 7.4 4.1 | -5.1 22.8 230 42 22 7.7 4.2 16000 -2.6 27.3 215 35 18 8.0 4.4 | -3.9 25.0 230 40 21 8.1 4.4 15500 -1.5 29.3 215 33 17 8.0 4.4 | -2.8 27.0 230 39 20 8.2 4.5 15000 -0.3 31.5 220 32 16 8.3 4.6 | -1.2 29.8 230 35 18 6.5 3.6 14500 1.0 33.8 225 31 16 8.3 4.6 | -0.3 31.5 230 32 17 6.6 3.6 14000 2.8 37.0 230 29 15 7.6 4.2 | 0.7 33.3 230 29 15 7.8 4.3 13500 4.0 39.2 235 28 15 7.8 4.3 | 1.8 35.2 230 25 13 7.7 4.2 13000 5.0 41.0 240 27 14 6.6 3.6 | 3.0 37.4 230 21 11 7.7 4.2 12500 6.0 42.8 245 24 12 6.6 3.6 | 4.1 39.4 230 18 10 7.8 4.3 12000 6.8 44.2 245 21 11 3.6 2.0 | 5.2 41.4 225 16 8 6.3 3.5 11500 7.1 44.8 245 17 9 2.8 1.5 | 6.0 42.8 225 14 7 6.0 3.3 11000 7.5 45.5 240 13 7 3.5 1.9 | 6.9 44.4 220 12 6 4.3 2.4 10500 8.0 46.4 225 10 5 3.4 1.9 | 7.4 45.3 210 11 6 3.5 1.9 10250 8.3 46.9 215 9 5 6.0 3.3 | 7.6 45.7 205 11 6 4.3 2.4 10000 8.7 47.7 200 9 5 5.8 3.2 | 7.9 46.2 200 10 5 3.3 1.8 9750 9.0 48.2 200 10 5 3.1 1.7 | 8.1 46.6 195 9 5 1.7 0.9 9500 9.2 48.6 200 11 6 3.5 1.9 | 8.2 46.8 185 8 4 2.4 1.3 9250 9.5 49.1 200 12 6 4.6 2.5 | 8.3 46.9 175 7 4 1.3 0.7 9000 9.8 49.6 210 13 7 -0.8 -0.5 | 8.4 47.1 145 7 3 1.9 1.1 8750 9.4 48.9 215 13 7 -6.5 -3.6 | 8.7 47.7 125 7 3 3.7 2.0 8500 9.0 48.2 220 13 7 -4.8 -2.6 | 9.0 48.2 110 8 4 2.4 1.3 8250 8.6 47.5 225 14 7 -6.7 -3.7 | 9.2 48.6 095 9 5 5.9 3.3 8000 8.1 46.6 215 10 5 -6.3 -3.4 | 9.9 49.8 095 10 5 10.3 5.6 7750 7.9 46.2 195 7 3 0.5 0.3 | 10.6 51.1 095 10 5 9.5 5.2 7500 8.1 46.6 165 5 3 1.7 0.9 | 11.3 52.3 090 10 5 8.9 4.9 7250 8.3 46.9 130 5 3 6.6 3.6 | 12.0 53.6 090 10 5 10.6 5.8 7000 9.1 48.4 130 6 3 12.5 6.9 | 12.9 55.2 090 10 5 11.9 6.5 6750 10.0 50.0 125 6 3 9.4 5.2 | 13.7 56.7 090 10 5 9.4 5.2 6500 10.6 51.1 125 6 3 9.1 5.0 | 14.4 57.9 090 10 5 9.2 5.1 6250 11.3 52.3 120 6 3 10.3 5.6 | 15.2 59.4 090 10 5 11.6 6.4 6000 12.1 53.8 120 6 3 10.9 6.0 | 16.1 61.0 090 10 5 12.8 7.0 5750 12.9 55.2 120 6 3 10.0 5.5 | 17.0 62.6 090 9 5 10.3 5.7 5500 13.8 56.8 115 6 3 15.4 8.5 | 17.8 64.0 090 9 5 16.4 9.0 06/18/2024 at 1500 MDT | 06/18/2024 at 1800 MDT | CAPE... 0.0 LI... +2.7 | CAPE... 0.0 LI... +2.9 CINH... 0.0 K Index... +16.5 | CINH... 0.0 K Index... +22.7 | 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 -57.6 -71.7 220 57 29 1.9 1.0 | -57.8 -72.0 225 58 30 2.1 1.2 45000 -55.0 -67.0 225 73 37 1.2 0.7 | -55.0 -67.0 225 74 38 0.9 0.5 40000 -52.9 -63.2 230 72 37 4.0 2.2 | -53.5 -64.3 230 75 39 4.2 2.3 38000 -49.8 -57.6 230 72 37 5.2 2.9 | -50.2 -58.4 235 73 38 5.4 3.0 36000 -46.7 -52.1 230 71 37 5.2 2.8 | -47.0 -52.6 235 72 37 5.4 2.9 34000 -42.9 -45.2 230 70 36 7.1 3.9 | -43.1 -45.6 235 70 36 7.2 3.9 32000 -38.6 -37.5 230 70 36 7.1 3.9 | -38.8 -37.8 240 68 35 7.2 3.9 30000 -34.3 -29.7 230 69 35 7.4 4.1 | -33.8 -28.8 240 67 34 7.5 4.1 29000 -31.5 -24.7 235 68 35 7.4 4.1 | -31.6 -24.9 240 66 34 7.5 4.1 28000 -29.3 -20.7 235 67 34 7.4 4.1 | -29.4 -20.9 240 66 34 7.7 4.2 27000 -27.1 -16.8 235 67 34 7.3 4.0 | -27.4 -17.3 240 65 34 6.4 3.5 26000 -24.9 -12.8 235 67 35 7.3 4.0 | -25.5 -13.9 240 65 33 6.4 3.5 25000 -22.7 -8.9 235 67 35 7.3 4.0 | -23.6 -10.5 240 65 33 6.5 3.5 24000 -20.5 -4.9 235 67 34 7.5 4.1 | -21.5 -6.7 235 62 32 7.3 4.0 23000 -18.3 -0.9 235 65 33 7.5 4.1 | -19.4 -2.9 235 59 30 7.4 4.1 22000 -16.1 3.0 240 63 33 7.4 4.1 | -17.2 1.0 230 55 28 7.5 4.1 21000 -14.2 6.4 240 59 30 5.7 3.1 | -14.9 5.2 230 50 26 8.0 4.4 20000 -12.6 9.3 240 53 27 5.7 3.1 | -12.6 9.3 230 45 23 8.0 4.4 19500 -11.8 10.8 240 50 26 5.8 3.2 | -11.5 11.3 230 42 22 8.1 4.4 19000 -10.9 12.4 240 47 24 6.1 3.4 | -10.3 13.5 230 40 21 8.3 4.5 18500 -9.9 14.2 240 44 23 7.9 4.3 | -9.0 15.8 230 38 20 8.9 4.9 18000 -8.8 16.2 240 42 22 7.8 4.3 | -7.7 18.1 225 36 19 9.0 4.9 17500 -7.7 18.1 240 40 20 8.3 4.6 | -6.6 20.1 225 35 18 6.5 3.6 17000 -6.4 20.5 235 39 20 8.5 4.7 | -5.7 21.7 225 34 17 6.2 3.4 16500 -5.2 22.6 235 38 19 8.5 4.7 | -4.8 23.4 225 32 17 6.3 3.5 16000 -3.9 25.0 235 37 19 8.6 4.7 | -3.8 25.2 225 31 16 6.7 3.7 15500 -2.7 27.1 235 35 18 8.6 4.7 | -2.4 27.7 225 30 15 6.5 3.6 15000 -0.9 30.4 230 33 17 7.8 4.3 | -1.5 29.3 220 28 15 6.3 3.4 14500 0.3 32.5 225 31 16 7.7 4.2 | -0.6 30.9 220 27 14 5.9 3.3 14000 1.1 34.0 225 28 14 4.8 2.6 | 0.1 32.2 215 25 13 3.8 2.1 13500 1.8 35.2 220 25 13 5.3 2.9 | 0.7 33.3 210 22 11 4.1 2.3 13000 2.4 36.3 215 21 11 2.0 1.1 | 1.1 34.0 205 18 9 1.3 0.7 12500 2.6 36.7 205 18 9 2.2 1.2 | 1.3 34.3 200 13 7 1.0 0.6 12000 2.9 37.2 195 14 7 1.8 1.0 | 2.0 35.6 180 8 4 7.6 4.2 11500 3.2 37.8 175 10 5 1.5 0.8 | 3.1 37.6 135 5 3 7.2 4.0 11000 3.8 38.8 145 8 4 6.7 3.7 | 4.2 39.6 100 7 3 8.4 4.6 10500 4.9 40.8 120 9 4 6.6 3.6 | 5.5 41.9 090 7 4 7.6 4.2 10250 5.5 41.9 110 9 5 11.2 6.1 | 6.1 43.0 085 8 4 11.8 6.5 10000 6.5 43.7 105 10 5 12.8 7.0 | 7.2 45.0 085 8 4 12.8 7.0 9750 7.3 45.1 100 10 5 9.3 5.1 | 7.9 46.2 085 8 4 9.2 5.1 9500 8.0 46.4 100 10 5 10.5 5.7 | 8.7 47.7 085 8 4 10.7 5.8 9250 8.8 47.8 100 10 5 9.3 5.1 | 9.4 48.9 080 8 4 8.5 4.7 9000 9.4 48.9 100 10 5 9.4 5.1 | 10.0 50.0 080 9 4 8.9 4.9 8750 10.2 50.4 100 10 5 10.4 5.7 | 10.8 51.4 080 9 4 11.0 6.0 8500 11.0 51.8 100 10 5 9.9 5.4 | 11.6 52.9 080 9 5 10.4 5.7 8250 11.7 53.1 100 10 5 10.9 6.0 | 12.4 54.3 080 9 5 10.5 5.8 8000 12.5 54.5 095 10 5 10.6 5.8 | 13.2 55.8 080 9 5 10.0 5.5 7750 13.3 55.9 095 10 5 8.9 4.9 | 13.9 57.0 075 9 5 9.5 5.2 7500 13.9 57.0 095 10 5 8.9 4.9 | 14.6 58.3 075 9 5 9.6 5.3 7250 14.6 58.3 095 10 5 10.5 5.7 | 15.3 59.5 075 9 5 10.0 5.5 7000 15.5 59.9 095 10 5 11.3 6.2 | 16.1 61.0 075 9 5 10.2 5.6 6750 16.3 61.3 095 10 5 10.2 5.6 | 16.8 62.2 075 9 5 9.2 5.0 6500 17.0 62.6 095 10 5 10.4 5.7 | 17.5 63.5 075 9 5 10.1 5.5 6250 17.8 64.0 095 10 5 11.5 6.3 | 18.3 64.9 075 9 5 11.7 6.4 6000 18.7 65.7 095 10 5 11.5 6.3 | 19.2 66.6 075 9 5 11.0 6.1 5750 19.5 67.1 095 10 5 11.1 6.1 | 20.0 68.0 075 9 5 11.5 6.3 5500 20.6 69.1 090 10 5 19.8 10.8 | 21.0 69.8 070 9 5 17.2 9.4 ________________________________________________________________________________ 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