Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000 UXUS97 KBOU 121259 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0659 MDT Friday, April 12, 2024 This forecast is for Friday, April 12, 2024: If the trigger temperature of 63.5 F/17.5 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1094 ft/min (5.6 m/s) Maximum height of thermals.................. 17742 ft MSL (12417 ft AGL) Forecast maximum temperature................... 76.0 F/24.9 C Time of trigger temperature.................... 1030 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................. 14653 ft MSL (9328 ft AGL) Thermal soaring outlook for Saturday 04/13..... Excellent Wave Soaring Index............................. Poor Wave Soaring Index trend (to 1800 MDT)......... Little change Height of stable layer (12-18K ft MSL)......... None Weak PVA/NVA (through 1800 MDT)................ Weak PVA Potential height of wave....................... 32325 ft MSL (27000 ft AGL) Wave soaring outlook for Saturday 04/13........ Poor Remarks... Warm and sunny through the weekend. Sunrise/Sunset.................... 06:25:04 / 19:35:02 MDT Total possible sunshine........... 13 hr 9 min 58 sec (789 min 58 sec) Altitude of sun at 13:00:03 MDT... 59.30 degrees Upper air data from numerical model forecast valid on 04/12/2024 at 0600 MDT Freezing level.................. 11512 ft MSL (6187 ft AGL) Convective condensation level... 19270 ft MSL (13945 ft AGL) Lifted condensation level....... 19106 ft MSL (13781 ft AGL) Lifted index.................... +0.4 K index......................... -0.0 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 -58.9 -74.0 280 48 25 0.5 0.3 M M M M M 45000 -58.1 -72.6 275 54 28 -0.5 -0.3 M M M M M 40000 -60.9 -77.6 270 48 24 -1.9 -1.0 M M M M M 38000 -59.5 -75.1 270 41 21 4.9 2.7 M M M M M 36000 -56.6 -69.9 265 32 16 4.9 2.7 M M M M M 34000 -53.1 -63.6 265 25 13 7.8 4.3 M M M M M 32000 -48.4 -55.1 265 25 13 7.9 4.3 M M M M M 30000 -43.6 -46.5 270 25 13 8.3 4.6 32.1 89.8 5.8 M M 29000 -40.5 -40.9 270 25 13 8.3 4.6 31.3 88.4 5.3 M M 28000 -38.0 -36.4 270 25 13 8.3 4.6 30.8 87.5 4.9 M M 27000 -35.5 -31.9 270 25 13 8.3 4.6 30.3 86.6 4.6 M M 26000 -33.0 -27.4 270 25 13 8.3 4.6 29.7 85.5 4.2 M M 25000 -30.6 -23.1 270 25 13 8.3 4.6 29.2 84.6 3.8 M M 24000 -28.1 -18.6 275 25 13 7.8 4.3 28.7 83.7 3.5 M M 23000 -25.8 -14.4 275 24 13 7.8 4.3 27.9 82.3 2.8 M M 22000 -23.4 -10.1 280 24 12 7.8 4.3 27.2 81.0 2.3 M M 21000 -21.1 -6.0 285 23 12 8.2 4.5 26.6 79.9 1.8 M M 20000 -18.6 -1.5 285 22 11 8.2 4.5 26.0 78.9 1.3 M M 19500 -17.4 0.7 285 22 11 8.2 4.5 25.8 78.4 1.1 M M 19000 -16.2 2.8 285 21 11 8.3 4.6 25.6 78.0 0.9 M M 18500 -15.0 5.0 290 21 11 7.3 4.0 25.2 77.4 0.6 M M 18000 -13.9 7.0 290 20 10 7.3 4.0 24.8 76.7 0.2 M M 17500 -12.8 9.0 290 19 10 7.1 3.9 24.4 75.9 -0.1 1080 5.5 17000 -11.8 10.8 290 19 10 6.8 3.7 23.9 75.0 -0.6 1035 5.3 16500 -10.8 12.6 295 18 9 6.8 3.7 23.4 74.1 -1.0 990 5.0 16000 -9.4 15.1 295 17 9 6.6 3.6 22.6 72.7 -1.8 924 4.7 15500 -8.4 16.9 295 17 9 6.6 3.6 22.1 71.7 -2.2 880 4.5 15000 -7.4 18.7 295 16 8 6.7 3.7 21.6 70.8 -2.8 836 4.2 14500 -6.4 20.5 295 16 8 6.7 3.7 21.0 69.9 -3.2 792 4.0 14000 -5.4 22.3 295 15 8 6.9 3.8 20.6 69.0 -3.7 747 3.8 13500 -4.4 24.1 295 15 8 6.8 3.7 20.1 68.2 -4.2 702 3.6 13000 -3.4 25.9 295 15 8 7.7 4.2 19.7 67.4 -4.6 655 3.3 12500 -2.2 28.0 295 14 7 7.6 4.2 19.3 66.8 -5.0 607 3.1 12000 -1.1 30.0 295 14 7 8.1 4.5 19.0 66.3 -5.3 558 2.8 11500 0.1 32.2 295 13 7 8.1 4.5 18.8 65.8 -5.6 507 2.6 11000 1.3 34.3 290 13 6 8.5 4.6 18.5 65.4 -5.9 456 2.3 10500 2.6 36.7 290 12 6 9.5 5.2 18.3 65.0 -6.1 404 2.1 10250 3.2 37.8 290 11 6 4.2 2.3 18.2 64.8 -6.2 378 1.9 10000 3.4 38.1 285 11 6 5.8 3.2 17.6 63.7 -6.8 365 1.9 9750 4.2 39.6 285 10 5 12.0 6.6 17.7 63.9 -6.7 334 1.7 9500 5.0 41.0 285 10 5 11.4 6.3 17.8 64.1 -6.7 302 1.5 9250 5.8 42.4 285 10 5 7.5 4.1 17.9 64.2 -6.6 270 1.4 9000 6.2 43.2 285 9 5 6.1 3.3 17.5 63.5 -7.0 252 1.3 8750 6.8 44.2 280 9 4 10.3 5.6 17.5 63.4 -7.1 224 1.1 8500 7.6 45.7 280 8 4 9.9 5.4 17.5 63.5 -7.1 195 1.0 8250 8.3 46.9 275 8 4 7.7 4.2 17.4 63.4 -7.1 167 0.8 8000 8.7 47.7 275 8 4 6.3 3.4 17.2 62.9 -7.4 145 0.7 7750 9.3 48.7 270 7 4 8.2 4.5 17.0 62.6 -7.6 122 0.6 7500 9.9 49.8 265 7 4 7.2 3.9 16.9 62.4 -7.7 96 0.5 7250 10.3 50.5 265 7 3 4.1 2.3 16.6 61.8 -8.1 77 0.4 7000 10.5 50.9 265 7 3 3.0 1.7 16.1 60.9 -8.6 62 0.3 6750 10.8 51.4 260 6 3 5.2 2.9 15.6 60.1 -9.1 46 0.2 6500 11.1 52.0 250 7 3 -0.6 -0.3 15.2 59.3 -9.5 30 0.2 6250 10.7 51.3 245 7 3 -7.6 -4.2 14.0 57.2 -10.8 36 0.2 6000 10.2 50.4 240 7 3 -3.5 -1.9 12.8 55.1 -12.0 42 0.2 5750 9.8 49.6 230 7 4 -13.0 -7.1 11.7 53.0 -13.1 48 0.2 5500 7.8 46.0 225 6 3 -39.8 -21.8 9.0 48.2 -15.9 101 0.5 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 04/12/2024 at 0900 MDT | 04/12/2024 at 1200 MDT | CAPE... 0.0 LI... +5.2 | CAPE... 0.0 LI... +4.1 CINH... -0.2 K Index... -5.5 | CINH... -0.1 K Index... -5.5 | 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 -59.2 -74.6 270 47 24 0.9 0.5 | -59.6 -75.3 270 48 25 0.8 0.4 45000 -57.9 -72.2 270 54 28 -1.6 -0.9 | -58.5 -73.3 265 52 27 -0.9 -0.5 40000 -60.0 -76.0 270 50 26 -1.4 -0.8 | -59.7 -75.5 265 54 28 -0.8 -0.4 38000 -58.4 -73.1 265 45 23 4.9 2.7 | -57.7 -71.9 260 53 27 5.5 3.0 36000 -55.5 -67.9 260 39 20 4.9 2.7 | -54.4 -65.9 260 51 26 5.5 3.0 34000 -52.2 -62.0 255 33 17 7.1 3.9 | -51.0 -59.8 260 48 25 6.1 3.3 32000 -47.9 -54.2 250 30 15 7.1 3.9 | -46.9 -52.4 260 40 20 6.1 3.3 30000 -42.8 -45.0 245 27 14 8.2 4.5 | -42.8 -45.0 255 34 18 7.8 4.3 29000 -40.4 -40.7 245 27 14 8.2 4.5 | -40.5 -40.9 255 33 17 7.7 4.3 28000 -37.9 -36.2 245 26 13 8.2 4.5 | -38.2 -36.8 255 31 16 7.8 4.3 27000 -35.5 -31.9 245 25 13 7.5 4.1 | -35.8 -32.4 255 30 15 7.9 4.4 26000 -33.3 -27.9 250 24 12 7.5 4.1 | -33.4 -28.1 255 28 15 7.9 4.4 25000 -31.0 -23.8 255 23 12 7.5 4.1 | -31.1 -24.0 255 27 14 7.9 4.4 24000 -28.7 -19.7 260 22 12 8.2 4.5 | -28.7 -19.7 260 25 13 8.1 4.4 23000 -26.3 -15.3 260 22 11 8.2 4.5 | -26.2 -15.2 260 24 12 8.1 4.4 22000 -23.8 -10.8 265 22 11 8.2 4.5 | -23.8 -10.8 260 23 12 8.1 4.4 21000 -21.3 -6.3 265 22 11 8.6 4.7 | -21.3 -6.3 260 22 11 8.5 4.7 20000 -18.7 -1.7 265 21 11 8.6 4.7 | -18.8 -1.8 260 21 11 8.5 4.7 19500 -17.5 0.5 265 20 10 8.6 4.7 | -17.5 0.5 260 21 11 8.5 4.7 19000 -16.2 2.8 265 20 10 8.7 4.8 | -16.3 2.7 260 21 11 8.5 4.7 18500 -15.0 5.0 270 19 10 7.5 4.1 | -15.0 5.0 260 20 10 8.3 4.5 18000 -13.8 7.2 270 18 9 7.6 4.2 | -13.8 7.2 260 19 10 8.3 4.5 17500 -12.7 9.1 270 17 9 7.3 4.0 | -12.5 9.5 260 18 9 7.8 4.3 17000 -11.6 11.1 275 16 8 7.0 3.9 | -11.4 11.5 260 17 9 7.5 4.1 16500 -10.6 12.9 275 15 8 7.0 3.8 | -9.8 14.4 265 16 8 7.3 4.0 16000 -9.0 15.8 280 14 7 7.0 3.8 | -8.7 16.3 265 15 8 7.2 4.0 15500 -8.0 17.6 280 13 7 7.0 3.9 | -7.6 18.3 270 14 7 7.1 3.9 15000 -6.9 19.6 280 13 7 7.1 3.9 | -6.6 20.1 270 13 7 7.0 3.8 14500 -5.9 21.4 285 12 6 7.1 3.9 | -5.5 22.1 270 12 6 7.0 3.9 14000 -4.8 23.4 285 12 6 7.1 3.9 | -4.5 23.9 270 11 6 7.6 4.2 13500 -3.8 25.2 285 11 6 7.1 3.9 | -3.3 26.1 275 11 5 7.5 4.1 13000 -2.7 27.1 285 11 6 7.5 4.1 | -2.2 28.0 275 10 5 7.8 4.3 12500 -1.6 29.1 285 10 5 7.4 4.1 | -1.0 30.2 270 9 5 7.8 4.3 12000 -0.5 31.1 285 10 5 8.0 4.4 | 0.2 32.4 270 9 5 8.5 4.7 11500 0.7 33.3 285 9 5 8.0 4.4 | 1.4 34.5 270 8 4 8.5 4.6 11000 1.9 35.4 280 8 4 8.4 4.6 | 2.7 36.9 265 8 4 8.8 4.8 10500 3.1 37.6 280 8 4 9.4 5.2 | 4.0 39.2 265 7 4 10.0 5.5 10250 3.8 38.8 275 8 4 4.1 2.2 | 4.6 40.3 260 7 3 4.1 2.3 10000 3.9 39.0 275 8 4 5.5 3.0 | 4.8 40.6 260 7 3 5.7 3.2 9750 4.7 40.5 275 8 4 11.6 6.4 | 5.6 42.1 260 6 3 12.5 6.9 9500 5.5 41.9 270 8 4 10.5 5.8 | 6.4 43.5 260 6 3 11.4 6.3 9250 6.2 43.2 270 8 4 6.7 3.7 | 7.2 45.0 255 5 3 6.4 3.5 9000 6.5 43.7 270 7 4 6.1 3.3 | 7.5 45.5 255 5 3 6.5 3.5 8750 7.2 45.0 265 7 4 10.5 5.8 | 8.3 46.9 250 4 2 11.8 6.5 8500 8.0 46.4 265 7 4 9.5 5.2 | 9.1 48.4 240 4 2 10.0 5.5 8250 8.6 47.5 260 7 3 6.9 3.8 | 9.7 49.5 230 4 2 7.1 3.9 8000 9.0 48.2 260 7 3 5.9 3.3 | 10.2 50.4 220 4 2 7.0 3.8 7750 9.6 49.3 255 6 3 9.2 5.1 | 10.9 51.6 215 4 2 11.5 6.3 7500 10.3 50.5 250 6 3 7.8 4.3 | 11.8 53.2 205 4 2 10.6 5.8 7250 10.7 51.3 250 6 3 4.2 2.3 | 12.4 54.3 200 4 2 7.5 4.1 7000 11.0 51.8 250 6 3 4.2 2.3 | 13.0 55.4 200 4 2 7.7 4.2 6750 11.3 52.3 245 6 3 5.8 3.2 | 13.7 56.7 200 4 2 13.0 7.1 6500 11.7 53.1 240 6 3 2.0 1.1 | 14.8 58.6 195 4 2 12.5 6.9 6250 11.6 52.9 235 6 3 -1.8 -1.0 | 15.5 59.9 195 4 2 8.9 4.9 6000 11.5 52.7 230 6 3 -1.4 -0.8 | 16.2 61.2 195 4 2 8.9 4.9 5750 11.4 52.5 225 6 3 1.3 0.7 | 16.9 62.4 195 4 2 14.1 7.8 5500 11.7 53.1 225 5 3 8.3 4.6 | 18.5 65.3 190 3 2 27.2 14.9 04/12/2024 at 1500 MDT | 04/12/2024 at 1800 MDT | CAPE... 0.0 LI... +2.6 | CAPE... +11.0 LI... +0.8 CINH... -0.1 K Index... +7.5 | CINH... -9.6 K Index... +15.5 | 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 -59.5 -75.1 265 48 25 1.2 0.7 | -59.1 -74.4 260 46 24 1.6 0.9 45000 -57.9 -72.2 255 55 28 -1.6 -0.9 | -56.9 -70.4 255 52 27 -2.5 -1.4 40000 -59.8 -75.6 260 59 30 -1.3 -0.7 | -60.0 -76.0 250 58 30 -2.1 -1.1 38000 -57.8 -72.0 260 59 30 6.0 3.3 | -58.0 -72.4 255 60 31 6.3 3.4 36000 -54.2 -65.6 255 58 30 5.9 3.3 | -53.8 -64.8 255 62 32 6.3 3.4 34000 -50.1 -58.2 255 54 28 6.4 3.5 | -49.9 -57.8 255 60 31 6.7 3.7 32000 -46.2 -51.2 255 46 24 6.4 3.5 | -45.9 -50.6 255 52 27 6.7 3.7 30000 -42.2 -44.0 250 39 20 7.1 3.9 | -41.9 -43.4 255 46 24 6.7 3.7 29000 -40.1 -40.2 250 36 18 7.1 3.9 | -39.8 -39.6 255 44 23 6.7 3.7 28000 -37.9 -36.2 250 33 17 7.1 3.9 | -37.8 -36.0 255 42 22 6.8 3.7 27000 -35.7 -32.3 245 31 16 8.1 4.4 | -35.7 -32.3 255 40 21 7.7 4.2 26000 -33.3 -27.9 245 30 16 8.0 4.4 | -33.4 -28.1 250 37 19 7.7 4.2 25000 -30.9 -23.6 245 29 15 8.0 4.4 | -31.1 -24.0 245 34 18 7.7 4.2 24000 -28.5 -19.3 245 28 15 8.3 4.6 | -28.8 -19.8 245 31 16 7.9 4.3 23000 -26.0 -14.8 245 28 14 8.3 4.6 | -26.5 -15.7 240 28 15 7.9 4.3 22000 -23.5 -10.3 245 27 14 8.3 4.6 | -24.1 -11.4 235 26 13 7.9 4.3 21000 -21.1 -6.0 245 26 14 7.9 4.3 | -21.7 -7.1 235 23 12 8.7 4.8 20000 -18.7 -1.7 250 25 13 8.0 4.4 | -19.1 -2.4 235 22 11 8.7 4.8 19500 -17.5 0.5 250 25 13 8.0 4.4 | -17.9 -0.2 230 21 11 8.7 4.8 19000 -16.3 2.7 250 24 12 8.0 4.4 | -15.9 3.4 230 20 10 8.5 4.6 18500 -15.1 4.8 250 23 12 8.0 4.4 | -14.7 5.5 230 19 10 8.3 4.5 18000 -14.0 6.8 255 23 12 8.0 4.4 | -13.5 7.7 230 19 10 8.3 4.5 17500 -12.2 10.0 255 22 11 8.1 4.5 | -12.3 9.9 230 18 9 8.3 4.6 17000 -11.0 12.2 255 21 11 8.1 4.5 | -11.0 12.2 230 17 9 8.3 4.6 16500 -9.8 14.4 255 20 11 8.3 4.5 | -9.7 14.5 225 16 8 9.0 5.0 16000 -8.5 16.7 255 19 10 8.3 4.6 | -8.4 16.9 225 15 8 9.3 5.1 15500 -7.3 18.9 255 18 9 8.4 4.6 | -7.0 19.4 225 14 7 9.3 5.1 15000 -6.0 21.2 255 16 8 8.5 4.7 | -5.5 22.1 220 14 7 9.4 5.2 14500 -4.7 23.5 255 15 8 8.5 4.7 | -4.1 24.6 220 13 7 9.4 5.2 14000 -3.5 25.7 255 13 7 8.4 4.6 | -2.7 27.1 215 12 6 9.4 5.2 13500 -2.2 28.0 255 11 6 8.4 4.6 | -1.3 29.7 215 11 6 9.4 5.2 13000 -0.9 30.4 250 9 5 9.0 4.9 | 0.1 32.2 210 10 5 9.4 5.2 12500 0.4 32.7 250 8 4 8.9 4.9 | 1.5 34.7 205 9 4 9.4 5.2 12000 1.8 35.2 245 7 3 9.0 5.0 | 2.9 37.2 200 7 4 9.1 5.0 11500 3.1 37.6 235 6 3 9.0 5.0 | 4.3 39.7 195 6 3 9.3 5.1 11000 4.5 40.1 225 5 3 9.2 5.0 | 5.6 42.1 185 5 3 7.7 4.2 10500 5.9 42.6 220 4 2 10.2 5.6 | 6.7 44.1 175 4 2 6.5 3.6 10250 6.5 43.7 215 4 2 4.8 2.6 | 7.3 45.1 170 3 2 12.4 6.8 10000 6.7 44.1 210 4 2 6.3 3.5 | 8.5 47.3 165 3 2 13.4 7.3 9750 7.6 45.7 205 4 2 12.5 6.9 | 9.2 48.6 155 3 2 8.0 4.4 9500 8.4 47.1 200 4 2 11.9 6.5 | 9.9 49.8 145 3 1 10.2 5.6 9250 9.3 48.7 190 3 2 7.6 4.2 | 10.6 51.1 135 3 1 6.9 3.8 9000 9.7 49.5 185 3 2 7.5 4.1 | 11.0 51.8 110 3 1 7.9 4.3 8750 10.5 50.9 185 3 2 12.2 6.7 | 11.8 53.2 105 3 1 11.3 6.2 8500 11.3 52.3 180 3 2 10.8 6.0 | 12.6 54.7 100 3 1 10.5 5.8 8250 12.1 53.8 175 3 1 8.5 4.6 | 13.4 56.1 095 3 1 8.8 4.8 8000 12.7 54.9 170 3 1 8.3 4.5 | 14.0 57.2 080 3 2 8.5 4.6 7750 13.4 56.1 165 3 1 11.8 6.5 | 14.7 58.5 075 3 2 11.0 6.0 7500 14.3 57.7 160 3 1 10.9 6.0 | 15.5 59.9 075 3 2 10.3 5.7 7250 15.0 59.0 155 3 1 8.0 4.4 | 16.2 61.2 070 3 2 8.0 4.4 7000 15.6 60.1 155 3 1 7.7 4.2 | 16.8 62.2 065 4 2 7.5 4.1 6750 16.3 61.3 150 3 1 12.7 7.0 | 17.5 63.5 060 4 2 11.7 6.4 6500 17.4 63.3 145 3 1 12.4 6.8 | 18.4 65.1 060 3 2 11.7 6.4 6250 18.1 64.6 140 3 1 9.2 5.1 | 19.1 66.4 060 4 2 9.0 4.9 6000 18.8 65.8 140 2 1 9.2 5.1 | 19.8 67.6 055 4 2 9.2 5.1 5750 19.6 67.3 135 2 1 13.2 7.2 | 20.5 68.9 050 4 2 10.3 5.7 5500 21.0 69.8 135 2 1 24.8 13.6 | 21.4 70.5 055 4 2 13.1 7.2 ________________________________________________________________________________ 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
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