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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000 UXUS97 KBOU 160054 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1854 MDT Wednesday, May 15, 2013 This forecast is for Thursday, May 16, 2013: If the trigger temperature of 75.4 F/24.1 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1434 ft/min (7.3 m/s) Maximum height of thermals.................. 19580 ft MSL (14293 ft AGL) Forecast maximum temperature................... 80.0 F/27.1 C Time of trigger temperature.................... 1130 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................. 8560 ft MSL (3273 ft AGL) Thermal soaring outlook for Friday 05/17....... Excellent 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 NVA Potential height of wave....................... 17831 ft MSL (12544 ft AGL) Wave soaring outlook for Friday 05/17.......... Poor Remarks... None Sunrise/Sunset.................... 05:43:50 / 20:07:41 MDT Total possible sunshine........... 14 hr 23 min 50 sec (863 min 50 sec) Altitude of sun at 12:55:58 MDT... 69.48 degrees Upper air data from numerical model forecast valid on 05/16/2013 at 0600 MDT Freezing level.................. 13668 ft MSL (8381 ft AGL) Convective condensation level... 14991 ft MSL (9704 ft AGL) Lifted condensation level....... 15682 ft MSL (10395 ft AGL) Lifted index.................... -5.0 K index......................... +21.3 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 -60.6 -77.1 275 28 14 0.7 0.4 M M M M M 45000 -59.6 -75.3 265 29 15 0.3 0.2 M M M M M 40000 -59.1 -74.4 275 40 21 0.1 0.0 M M M M M 38000 -55.5 -67.9 275 41 21 7.3 4.0 M M M M M 36000 -51.2 -60.2 275 42 21 7.3 4.0 M M M M M 34000 -46.9 -52.4 270 39 20 6.9 3.8 M M M M M 32000 -42.8 -45.0 265 34 17 6.9 3.8 M M M M M 30000 -38.3 -36.9 250 28 14 6.3 3.4 36.9 98.4 7.7 M M 29000 -36.5 -33.7 245 25 13 6.3 3.5 35.5 95.9 6.8 M M 28000 -34.6 -30.3 235 23 12 6.3 3.5 34.3 93.7 5.9 M M 27000 -32.6 -26.7 225 21 11 6.8 3.7 33.0 91.5 5.0 M M 26000 -30.6 -23.1 215 19 10 6.8 3.8 31.9 89.4 4.1 M M 25000 -28.6 -19.5 205 17 9 6.9 3.8 30.8 87.5 3.3 M M 24000 -26.4 -15.5 195 17 9 8.6 4.7 30.0 86.0 2.6 M M 23000 -23.9 -11.0 195 16 8 8.5 4.6 29.4 85.0 2.1 M M 22000 -21.4 -6.5 195 15 8 8.5 4.6 29.0 84.2 1.8 M M 21000 -19.1 -2.4 195 14 7 7.1 3.9 28.4 83.1 1.2 M M 20000 -17.0 1.4 205 13 7 7.2 3.9 27.4 81.3 0.4 M M 19500 -15.9 3.4 210 13 7 7.2 3.9 27.0 80.6 -0.0 1431 7.3 19000 -14.9 5.2 220 13 7 7.2 3.9 26.6 79.8 -0.4 1385 7.0 18500 -13.7 7.3 225 13 7 7.9 4.3 26.2 79.2 -0.7 1336 6.8 18000 -12.6 9.3 235 14 7 7.8 4.3 25.9 78.5 -1.0 1287 6.5 17500 -11.4 11.5 240 14 7 8.5 4.7 25.6 78.0 -1.3 1237 6.3 17000 -10.1 13.8 250 14 7 8.9 4.9 25.4 77.7 -1.5 1182 6.0 16500 -8.7 16.3 255 14 7 9.1 5.0 25.3 77.5 -1.6 1127 5.7 16000 -7.3 18.9 260 14 7 10.1 5.6 25.3 77.5 -1.6 1069 5.4 15500 -5.8 21.6 260 14 7 10.1 5.5 25.3 77.6 -1.6 1009 5.1 15000 -3.6 25.5 265 14 7 9.8 5.4 25.4 77.7 -1.6 920 4.7 14500 -2.1 28.2 265 14 7 9.8 5.4 25.4 77.7 -1.6 862 4.4 14000 -0.7 30.7 270 14 7 9.6 5.3 25.4 77.6 -1.6 804 4.1 13500 0.8 33.4 275 14 7 9.6 5.3 25.3 77.6 -1.6 746 3.8 13000 2.2 36.0 275 14 7 9.6 5.3 25.3 77.6 -1.7 689 3.5 12500 3.6 38.5 280 14 7 9.7 5.3 25.3 77.5 -1.7 631 3.2 12000 5.0 41.0 285 14 7 9.3 5.1 25.3 77.5 -1.8 575 2.9 11500 6.4 43.5 290 13 7 9.3 5.1 25.2 77.3 -1.9 519 2.6 11000 7.7 45.9 290 13 7 8.5 4.7 25.1 77.1 -2.1 465 2.4 10500 8.9 48.0 295 13 7 8.1 4.4 24.9 76.7 -2.3 413 2.1 10250 9.6 49.3 295 13 7 11.3 6.2 24.8 76.6 -2.4 386 2.0 10000 10.5 50.9 295 12 6 11.2 6.1 25.0 77.0 -2.2 351 1.8 9750 11.1 52.0 290 11 6 8.3 4.5 24.9 76.9 -2.3 325 1.6 9500 11.8 53.2 290 11 5 9.2 5.1 24.9 76.8 -2.4 298 1.5 9250 12.4 54.3 285 10 5 8.5 4.6 24.8 76.7 -2.5 272 1.4 9000 13.0 55.4 280 9 5 7.6 4.2 24.7 76.4 -2.7 247 1.3 8750 13.5 56.3 275 8 4 7.4 4.1 24.5 76.1 -2.9 224 1.1 8500 14.0 57.2 270 8 4 7.7 4.2 24.3 75.8 -3.1 200 1.0 8250 14.6 58.3 260 7 4 6.8 3.7 24.2 75.5 -3.3 177 0.9 8000 15.0 59.0 250 7 4 5.5 3.0 23.9 75.0 -3.6 157 0.8 7750 15.4 59.7 240 7 4 5.3 2.9 23.5 74.4 -3.9 138 0.7 7500 15.8 60.4 230 7 4 5.3 2.9 23.2 73.7 -4.3 119 0.6 7250 16.2 61.2 225 7 4 5.7 3.1 22.9 73.2 -4.6 100 0.5 7000 16.6 61.9 230 7 4 5.9 3.3 22.6 72.6 -4.9 79 0.4 6750 17.1 62.8 240 7 4 7.7 4.2 22.3 72.2 -5.2 57 0.3 6500 17.6 63.7 250 7 4 4.3 2.4 22.1 71.8 -5.4 34 0.2 6250 17.6 63.7 250 7 4 -3.5 -1.9 21.4 70.5 -6.2 29 0.1 6000 17.1 62.8 250 8 4 -5.3 -2.9 20.3 68.5 -7.4 34 0.2 5750 16.6 61.9 250 8 4 -9.8 -5.4 19.1 66.3 -8.7 44 0.2 5500 15.1 59.2 245 8 4 -29.4 -16.1 17.0 62.5 -10.9 80 0.4 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 05/16/2013 at 0900 MDT | 05/16/2013 at 1200 MDT | K index... +20.1 LI... -3.1 | K index... +19.6 LI... -1.4 CAPE... +198.2 CIN... -59.5 | CAPE... +44.8 CIN... -10.0 | 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 -60.9 -77.6 270 28 14 0.5 0.3 | -61.0 -77.8 260 26 13 0.0 0.0 45000 -60.2 -76.4 265 30 16 -0.8 -0.5 | -61.1 -78.0 265 29 15 -0.5 -0.3 40000 -61.4 -78.5 280 33 17 -1.4 -0.7 | -61.9 -79.4 275 28 14 -1.4 -0.8 38000 -57.4 -71.3 285 34 17 8.1 4.5 | -57.7 -71.9 275 28 15 8.3 4.6 36000 -52.6 -62.7 295 35 18 8.1 4.5 | -52.7 -62.9 280 30 15 8.3 4.6 34000 -47.6 -53.7 295 36 19 8.6 4.7 | -47.7 -53.9 280 31 16 8.5 4.7 32000 -42.4 -44.3 300 37 19 8.6 4.7 | -42.5 -44.5 280 32 16 8.5 4.7 30000 -37.4 -35.3 300 37 19 8.0 4.4 | -36.8 -34.2 280 31 16 8.4 4.6 29000 -34.4 -29.9 300 36 19 8.0 4.4 | -34.3 -29.7 280 29 15 8.4 4.6 28000 -32.0 -25.6 300 36 18 8.0 4.4 | -31.8 -25.2 280 28 14 8.4 4.6 27000 -29.8 -21.6 300 34 17 7.0 3.9 | -29.5 -21.1 285 26 14 7.3 4.0 26000 -27.7 -17.9 300 30 16 7.0 3.8 | -27.4 -17.3 290 25 13 7.2 4.0 25000 -25.6 -14.1 300 27 14 7.0 3.8 | -25.2 -13.4 295 25 13 7.2 4.0 24000 -23.7 -10.7 300 24 12 5.2 2.9 | -23.1 -9.6 295 24 12 6.9 3.8 23000 -22.1 -7.8 290 19 10 5.4 2.9 | -21.0 -5.8 295 22 11 7.0 3.8 22000 -20.5 -4.9 280 15 8 5.4 3.0 | -19.0 -2.2 295 21 11 7.0 3.8 21000 -18.8 -1.8 270 12 6 6.4 3.5 | -17.1 1.2 290 20 10 6.2 3.4 20000 -16.9 1.6 260 11 6 6.4 3.5 | -15.3 4.5 285 19 10 6.2 3.4 19500 -16.0 3.2 255 11 6 6.4 3.5 | -14.4 6.1 285 18 9 6.2 3.4 19000 -15.1 4.8 250 11 5 6.5 3.6 | -13.5 7.7 285 18 9 6.3 3.4 18500 -13.9 7.0 245 11 6 8.8 4.8 | -12.4 9.7 280 17 9 7.4 4.1 18000 -12.7 9.1 245 11 6 8.6 4.7 | -11.4 11.5 280 16 8 7.3 4.0 17500 -11.4 11.5 245 11 6 8.9 4.9 | -10.3 13.5 280 16 8 7.6 4.2 17000 -10.1 13.8 255 11 6 9.1 5.0 | -9.1 15.6 280 15 8 7.7 4.2 16500 -8.7 16.3 260 11 6 9.1 5.0 | -8.0 17.6 280 14 7 7.7 4.2 16000 -7.4 18.7 270 12 6 8.8 4.8 | -6.9 19.6 285 14 7 7.6 4.2 15500 -6.1 21.0 275 12 6 8.8 4.8 | -5.7 21.7 290 13 7 7.7 4.2 15000 -4.1 24.6 285 14 7 9.4 5.1 | -4.1 24.6 295 13 7 7.6 4.1 14500 -2.7 27.1 290 15 8 9.3 5.1 | -2.9 26.8 300 13 7 7.7 4.2 14000 -1.4 29.5 295 16 8 9.2 5.0 | -1.7 28.9 305 13 7 8.7 4.8 13500 -0.0 32.0 295 16 8 9.1 5.0 | -0.4 31.3 310 14 7 8.6 4.7 13000 1.4 34.5 300 17 9 9.6 5.3 | 0.9 33.6 315 14 7 9.6 5.3 12500 2.8 37.0 300 17 9 9.6 5.3 | 2.3 36.1 315 14 7 9.4 5.2 12000 4.2 39.6 300 18 9 9.4 5.2 | 3.8 38.8 315 14 7 10.0 5.5 11500 5.6 42.1 300 18 9 9.6 5.3 | 5.3 41.5 320 14 7 10.1 5.5 11000 6.9 44.4 300 18 9 8.0 4.4 | 6.7 44.1 320 14 7 8.5 4.7 10500 8.1 46.6 300 18 9 7.6 4.2 | 7.9 46.2 320 14 7 8.8 4.8 10250 8.8 47.8 300 18 9 10.6 5.8 | 8.7 47.7 320 14 7 12.0 6.6 10000 9.6 49.3 295 17 9 10.4 5.7 | 9.6 49.3 320 14 7 11.1 6.1 9750 10.2 50.4 295 16 8 7.7 4.2 | 10.2 50.4 320 13 7 8.4 4.6 9500 10.8 51.4 295 16 8 8.3 4.6 | 10.9 51.6 320 13 7 9.2 5.0 9250 11.4 52.5 295 15 8 8.4 4.6 | 11.5 52.7 320 13 6 8.9 4.9 9000 12.1 53.8 295 14 7 8.6 4.7 | 12.2 54.0 320 12 6 9.5 5.2 8750 12.7 54.9 295 14 7 8.5 4.7 | 12.9 55.2 320 11 6 10.0 5.5 8500 13.3 55.9 295 13 7 8.4 4.6 | 13.6 56.5 320 11 6 9.8 5.4 8250 13.9 57.0 295 12 6 8.9 4.9 | 14.3 57.7 320 10 5 10.2 5.6 8000 14.6 58.3 295 12 6 8.2 4.5 | 15.1 59.2 320 10 5 9.9 5.4 7750 15.1 59.2 295 11 6 7.0 3.8 | 15.8 60.4 320 10 5 9.2 5.0 7500 15.6 60.1 300 11 6 7.2 4.0 | 16.5 61.7 320 10 5 9.5 5.2 7250 16.2 61.2 300 11 6 8.9 4.9 | 17.2 63.0 320 10 5 10.9 6.0 7000 16.9 62.4 305 12 6 9.4 5.1 | 18.1 64.6 320 10 5 11.1 6.1 6750 17.6 63.7 305 12 6 8.4 4.6 | 18.8 65.8 320 10 5 8.8 4.8 6500 18.2 64.8 310 13 6 6.8 3.7 | 19.4 66.9 320 9 5 9.4 5.2 6250 18.5 65.3 310 11 6 5.2 2.9 | 20.2 68.4 320 9 5 11.3 6.2 6000 18.8 65.8 310 9 5 5.1 2.8 | 21.1 70.0 320 9 5 11.0 6.0 5750 19.1 66.4 315 6 3 6.1 3.4 | 21.9 71.4 320 9 5 11.4 6.2 5500 19.6 67.3 310 4 2 12.2 6.7 | 22.9 73.2 320 8 4 18.3 10.0 05/16/2013 at 1500 MDT | 05/16/2013 at 1800 MDT | K index... +20.0 LI... -0.9 | K index... +24.9 LI... -1.3 CAPE... +40.2 CIN... -41.4 | CAPE... +97.4 CIN... -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 -61.6 -78.9 255 22 12 -0.3 -0.2 | -62.0 -79.6 255 24 12 -0.8 -0.4 45000 -62.1 -79.8 275 25 13 0.2 0.1 | -62.9 -81.2 275 26 14 0.7 0.4 40000 -61.7 -79.1 275 29 15 -0.6 -0.4 | -61.8 -79.2 280 29 15 -0.0 -0.0 38000 -57.5 -71.5 275 29 15 8.1 4.5 | -57.4 -71.3 275 28 14 8.2 4.5 36000 -52.6 -62.7 275 29 15 8.1 4.5 | -52.5 -62.5 275 26 14 8.2 4.5 34000 -47.6 -53.7 275 29 15 8.6 4.7 | -47.5 -53.5 275 26 13 8.5 4.7 32000 -42.4 -44.3 270 28 15 8.6 4.7 | -42.4 -44.3 275 27 14 8.5 4.7 30000 -36.7 -34.1 270 28 14 8.5 4.7 | -36.7 -34.1 275 26 14 8.4 4.6 29000 -34.2 -29.6 275 27 14 8.5 4.7 | -34.2 -29.6 275 26 13 8.4 4.6 28000 -31.6 -24.9 275 27 14 8.5 4.7 | -31.7 -25.1 275 26 13 8.5 4.7 27000 -29.3 -20.7 275 27 14 7.4 4.1 | -29.4 -20.9 275 25 13 7.4 4.1 26000 -27.1 -16.8 275 26 13 7.4 4.1 | -27.1 -16.8 275 24 12 7.4 4.1 25000 -24.9 -12.8 280 25 13 7.4 4.1 | -24.9 -12.8 270 22 12 7.5 4.1 24000 -22.7 -8.9 280 24 12 6.9 3.8 | -22.7 -8.9 270 22 11 7.3 4.0 23000 -20.7 -5.3 280 23 12 7.0 3.8 | -20.6 -5.1 270 22 11 7.3 4.0 22000 -18.6 -1.5 280 23 12 7.0 3.8 | -18.4 -1.1 270 22 12 7.4 4.0 21000 -16.6 2.1 280 22 11 6.8 3.7 | -16.3 2.7 265 22 12 7.1 3.9 20000 -14.6 5.7 275 23 12 6.8 3.7 | -14.2 6.4 265 22 11 7.1 3.9 19500 -13.6 7.5 275 23 12 6.8 3.7 | -13.2 8.2 265 22 11 7.1 3.9 19000 -12.6 9.3 275 23 12 6.9 3.8 | -12.1 10.2 260 22 11 7.1 3.9 18500 -11.5 11.3 275 22 12 7.9 4.3 | -11.1 12.0 260 21 11 7.0 3.9 18000 -10.3 13.5 275 21 11 7.8 4.3 | -10.1 13.8 260 21 11 7.1 3.9 17500 -9.2 15.4 275 21 11 8.1 4.5 | -9.0 15.8 260 20 10 7.3 4.0 17000 -7.9 17.8 280 20 10 8.2 4.5 | -8.0 17.6 260 19 10 7.4 4.1 16500 -6.7 19.9 280 20 10 8.3 4.5 | -6.9 19.6 260 19 10 7.6 4.2 16000 -5.5 22.1 280 20 10 8.3 4.6 | -5.7 21.7 265 18 9 8.2 4.5 15500 -3.7 25.3 285 19 10 8.5 4.6 | -4.5 23.9 265 17 9 8.1 4.4 15000 -2.4 27.7 285 18 9 8.7 4.7 | -2.5 27.5 265 15 8 9.0 5.0 14500 -1.1 30.0 280 18 9 8.6 4.7 | -1.2 29.8 265 14 7 9.2 5.0 14000 0.1 32.2 280 17 9 8.1 4.5 | 0.2 32.4 265 13 7 9.7 5.3 13500 1.3 34.3 280 16 8 8.1 4.4 | 1.7 35.1 265 12 6 9.7 5.3 13000 2.5 36.5 280 15 8 9.0 5.0 | 3.1 37.6 265 11 6 9.9 5.4 12500 3.8 38.8 280 13 7 9.0 4.9 | 4.6 40.3 270 10 5 10.0 5.5 12000 5.2 41.4 280 12 6 8.7 4.8 | 5.9 42.6 270 9 5 8.2 4.5 11500 6.5 43.7 285 10 5 8.8 4.8 | 7.2 45.0 270 8 4 8.3 4.6 11000 7.7 45.9 290 8 4 7.4 4.1 | 8.4 47.1 270 6 3 8.3 4.6 10500 8.7 47.7 295 6 3 7.5 4.1 | 9.6 49.3 270 4 2 8.9 4.9 10250 9.3 48.7 305 4 2 9.8 5.4 | 10.3 50.5 270 3 2 9.9 5.4 10000 10.1 50.2 320 4 2 10.1 5.5 | 11.0 51.8 285 2 1 8.4 4.6 9750 10.8 51.4 325 3 2 8.8 4.8 | 11.6 52.9 305 2 1 7.4 4.1 9500 11.4 52.5 330 3 2 9.1 5.0 | 12.1 53.8 330 2 1 7.6 4.2 9250 12.1 53.8 340 3 2 9.4 5.1 | 12.6 54.7 355 2 1 7.9 4.3 9000 12.8 55.0 340 3 2 10.0 5.5 | 13.3 55.9 355 3 1 9.2 5.0 8750 13.5 56.3 345 3 2 10.0 5.5 | 14.0 57.2 355 3 1 9.8 5.4 8500 14.3 57.7 345 3 2 10.0 5.5 | 14.7 58.5 360 3 2 9.5 5.2 8250 15.0 59.0 345 3 2 10.1 5.6 | 15.4 59.7 360 3 2 10.2 5.6 8000 15.8 60.4 345 3 2 10.0 5.5 | 16.2 61.2 360 3 2 10.2 5.6 7750 16.5 61.7 345 3 2 9.6 5.3 | 16.9 62.4 360 3 2 9.6 5.2 7500 17.2 63.0 345 3 2 9.7 5.3 | 17.6 63.7 360 4 2 9.7 5.3 7250 18.0 64.4 345 4 2 10.3 5.6 | 18.3 64.9 355 4 2 9.9 5.4 7000 18.8 65.8 345 4 2 10.4 5.7 | 19.1 66.4 355 4 2 10.0 5.5 6750 19.5 67.1 345 4 2 9.6 5.2 | 19.8 67.6 355 4 2 9.8 5.4 6500 20.2 68.4 345 4 2 10.1 5.5 | 20.6 69.1 355 4 2 10.0 5.5 6250 21.0 69.8 345 4 2 11.3 6.2 | 21.3 70.3 355 4 2 10.3 5.6 6000 21.9 71.4 345 4 2 11.5 6.3 | 22.1 71.8 350 4 2 10.3 5.6 5750 22.7 72.9 345 4 2 10.0 5.5 | 22.8 73.0 350 4 2 9.7 5.3 5500 23.5 74.3 345 4 2 15.2 8.3 | 23.6 74.5 350 4 2 11.8 6.5 ________________________________________________________________________________ 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. CIN (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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