Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
399 UXUS97 KBOU 140034 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1830 MDT Thursday, June 13, 2024 This forecast is for Friday, June 14, 2024: If the trigger temperature of 77.4 F/25.2 C is reached...then Thermal Soaring Index....................... Good Maximum rate of lift........................ 665 ft/min (3.4 m/s) Maximum height of thermals.................. 12012 ft MSL (6706 ft AGL) Forecast maximum temperature................... 86.0 F/30.5 C Time of trigger temperature.................... 1000 MDT Time of overdevelopment........................ 1500 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 10297 ft MSL (4992 ft AGL) Thermal soaring outlook for Saturday 06/15..... 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 PVA Potential height of wave....................... 22293 ft MSL (16987 ft AGL) Wave soaring outlook for Saturday 06/15........ Poor Remarks... Scattered to numerous thunderstorms Friday afternoon Sunrise/Sunset.................... 05:30:49 / 20:29:05 MDT Total possible sunshine........... 14 hr 58 min 17 sec (898 min 17 sec) Altitude of sun at 12:59:57 MDT... 73.54 degrees Upper air data from numerical model forecast valid on 06/14/2024 at 0600 MDT Freezing level.................. 16344 ft MSL (11038 ft AGL) Convective condensation level... 14591 ft MSL (9285 ft AGL) Lifted condensation level....... 13752 ft MSL (8446 ft AGL) Lifted index.................... -5.4 K index......................... +26.8 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 -60.7 -77.3 245 31 16 1.1 0.6 M M M M M 45000 -57.6 -71.7 235 44 23 3.9 2.1 M M M M M 40000 -51.8 -61.2 240 45 23 4.0 2.2 M M M M M 38000 -49.4 -56.9 240 37 19 4.0 2.2 M M M M M 36000 -47.0 -52.6 245 30 16 3.8 2.1 M M M M M 34000 -42.7 -44.9 240 28 14 7.8 4.3 M M M M M 32000 -37.4 -35.3 235 27 14 8.2 4.5 M M M M M 30000 -32.1 -25.8 240 24 12 9.0 4.9 43.2 109.7 10.0 M M 29000 -29.4 -20.9 245 22 12 9.0 4.9 42.9 109.3 9.9 M M 28000 -26.8 -16.2 250 21 11 7.5 4.1 42.6 108.7 9.8 M M 27000 -24.6 -12.3 245 21 11 7.4 4.1 41.6 106.9 9.1 M M 26000 -22.4 -8.3 240 20 10 7.4 4.1 40.7 105.3 8.5 M M 25000 -20.3 -4.5 235 20 10 7.3 4.0 40.0 104.0 7.9 M M 24000 -18.2 -0.8 230 22 12 7.1 3.9 38.9 102.1 7.1 M M 23000 -16.1 3.0 225 25 13 7.1 3.9 37.9 100.3 6.3 M M 22000 -14.0 6.8 220 28 14 7.4 4.0 37.1 98.8 5.6 M M 21000 -11.8 10.8 220 24 12 7.7 4.2 36.3 97.3 4.9 M M 20000 -9.5 14.9 220 19 10 7.8 4.3 35.6 96.0 4.3 M M 19500 -8.4 16.9 220 17 9 7.8 4.3 35.3 95.5 4.0 M M 19000 -7.2 19.0 220 15 8 7.7 4.2 34.9 94.9 3.7 M M 18500 -6.1 21.0 220 13 7 7.8 4.3 34.6 94.2 3.4 M M 18000 -5.0 23.0 220 11 6 8.7 4.8 34.2 93.6 3.1 M M 17500 -3.5 25.7 215 10 5 9.7 5.3 34.2 93.6 3.1 M M 17000 -2.1 28.2 210 9 4 9.9 5.4 34.2 93.6 3.2 M M 16500 -0.1 31.8 210 6 3 8.6 4.7 34.0 93.2 2.9 M M 16000 1.1 34.0 205 5 2 8.6 4.7 33.8 92.9 2.7 M M 15500 2.4 36.3 210 4 2 8.4 4.6 33.6 92.5 2.5 M M 15000 3.6 38.5 215 4 2 8.4 4.6 33.4 92.1 2.3 M M 14500 4.9 40.8 220 4 2 8.2 4.5 33.2 91.7 2.1 M M 14000 6.1 43.0 220 5 2 8.2 4.5 32.9 91.2 1.9 M M 13500 7.2 45.0 220 5 3 7.1 3.9 32.6 90.7 1.6 M M 13000 8.2 46.8 220 5 3 6.6 3.6 32.1 89.7 1.1 M M 12500 9.1 48.4 220 6 3 6.3 3.5 31.6 88.8 0.6 M M 12000 9.9 49.8 220 6 3 6.1 3.3 31.0 87.8 -0.1 460 2.3 11500 10.8 51.4 220 7 4 5.5 3.0 30.4 86.7 -0.7 421 2.1 11000 11.3 52.3 215 8 4 4.4 2.4 29.6 85.3 -1.6 388 2.0 10500 11.9 53.4 215 9 5 2.3 1.2 28.8 83.8 -2.5 357 1.8 10250 11.9 53.4 215 9 5 1.9 1.1 28.1 82.5 -3.2 348 1.8 10000 12.2 54.0 205 11 5 5.6 3.1 27.7 81.8 -3.6 332 1.7 9750 12.6 54.7 200 12 6 5.4 2.9 27.3 81.2 -4.0 313 1.6 9500 13.0 55.4 190 15 7 5.6 3.1 27.0 80.6 -4.4 295 1.5 9250 13.4 56.1 190 16 8 5.8 3.2 26.7 80.0 -4.7 274 1.4 9000 13.9 57.0 185 16 8 6.8 3.8 26.4 79.5 -4.9 252 1.3 8750 14.5 58.1 185 17 9 8.3 4.5 26.2 79.2 -5.0 226 1.1 8500 15.1 59.2 180 17 9 6.0 3.3 26.1 78.9 -5.2 201 1.0 8250 15.4 59.7 180 16 8 4.0 2.2 25.7 78.2 -5.6 184 0.9 8000 15.7 60.3 180 15 8 4.7 2.6 25.3 77.5 -6.1 168 0.9 7750 16.0 60.8 180 14 7 5.0 2.7 24.9 76.8 -6.5 151 0.8 7500 16.4 61.5 180 13 6 5.9 3.2 24.5 76.2 -6.9 134 0.7 7250 16.8 62.2 175 12 6 6.3 3.4 24.3 75.7 -7.2 114 0.6 7000 17.2 63.0 175 12 6 6.5 3.6 24.0 75.2 -7.6 95 0.5 6750 17.6 63.7 170 12 6 5.0 2.7 23.7 74.7 -7.9 76 0.4 6500 17.8 64.0 175 10 5 2.7 1.5 23.3 73.9 -8.5 62 0.3 6250 17.9 64.2 175 7 4 2.2 1.2 22.7 72.9 -9.1 51 0.3 6000 18.0 64.4 180 5 3 3.4 1.8 22.2 71.9 -9.7 40 0.2 5750 18.3 64.9 185 3 2 3.6 2.0 21.7 71.1 -10.2 26 0.1 5500 18.4 65.1 180 3 1 1.0 0.5 21.2 70.1 -10.9 15 0.1 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 06/14/2024 at 0900 MDT | 06/14/2024 at 1200 MDT | CAPE... +1154.4 LI... -3.2 | CAPE... +1390.6 LI... -3.9 CINH... -169.8 K Index... +23.6 | CINH... -61.5 K Index... +22.4 | 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 -60.0 -76.0 240 27 14 1.9 1.0 | -59.0 -74.2 240 26 14 2.8 1.5 45000 -56.7 -70.1 230 43 22 2.6 1.4 | -55.2 -67.4 235 44 23 1.6 0.9 40000 -52.6 -62.7 230 43 22 3.8 2.1 | -52.6 -62.7 235 42 21 3.9 2.2 38000 -50.3 -58.5 225 35 18 3.8 2.1 | -50.2 -58.4 230 33 17 3.9 2.1 36000 -48.0 -54.4 220 28 14 3.5 1.9 | -47.9 -54.2 220 25 13 3.8 2.1 34000 -43.4 -46.1 220 26 14 8.7 4.7 | -43.5 -46.3 210 23 12 8.3 4.6 32000 -37.5 -35.5 220 26 13 9.1 5.0 | -37.9 -36.2 205 23 12 8.2 4.5 30000 -32.5 -26.5 220 24 13 8.5 4.7 | -32.7 -26.9 210 22 11 8.7 4.7 29000 -29.9 -21.8 220 24 12 8.5 4.7 | -30.1 -22.2 215 22 11 8.7 4.8 28000 -27.4 -17.3 225 23 12 8.1 4.5 | -27.6 -17.7 215 22 11 7.9 4.3 27000 -25.0 -13.0 225 26 13 8.1 4.4 | -25.3 -13.5 220 25 13 7.7 4.2 26000 -22.6 -8.7 230 29 15 8.1 4.5 | -23.0 -9.4 220 28 14 7.7 4.2 25000 -20.2 -4.4 235 31 16 7.9 4.3 | -20.7 -5.3 220 30 16 7.7 4.2 24000 -18.1 -0.6 230 34 17 7.0 3.9 | -18.6 -1.5 225 32 16 7.3 4.0 23000 -16.0 3.2 225 36 19 7.1 3.9 | -16.5 2.3 225 34 17 7.3 4.0 22000 -13.9 7.0 225 39 20 7.3 4.0 | -14.3 6.3 225 35 18 7.5 4.1 21000 -11.7 10.9 225 35 18 7.6 4.2 | -12.0 10.4 225 34 17 7.8 4.3 20000 -9.5 14.9 220 31 16 7.6 4.2 | -9.8 14.4 225 32 17 7.9 4.3 19500 -8.3 17.1 220 29 15 7.5 4.1 | -8.6 16.5 225 32 16 7.9 4.3 19000 -7.1 19.2 215 27 14 9.0 4.9 | -7.5 18.5 225 31 16 8.0 4.4 18500 -5.8 21.6 210 25 13 8.9 4.9 | -6.3 20.7 220 30 15 8.0 4.4 18000 -4.5 23.9 205 23 12 8.8 4.8 | -5.1 22.8 215 29 15 8.3 4.6 17500 -3.2 26.2 200 21 11 8.7 4.8 | -3.8 25.2 215 27 14 8.7 4.8 17000 -1.3 29.7 195 18 9 8.6 4.7 | -1.8 28.8 210 24 13 9.1 5.0 16500 -0.0 32.0 195 16 8 8.4 4.6 | -0.4 31.3 205 23 12 9.5 5.2 16000 1.2 34.2 195 14 7 8.4 4.6 | 1.0 33.8 200 21 11 9.5 5.2 15500 2.5 36.5 195 13 6 8.5 4.6 | 2.3 36.1 195 19 10 8.6 4.7 15000 3.7 38.7 195 11 6 8.5 4.7 | 3.6 38.5 195 17 9 8.8 4.8 14500 4.9 40.8 195 9 5 8.2 4.5 | 4.8 40.6 190 14 7 6.9 3.8 14000 6.1 43.0 200 8 4 8.2 4.5 | 5.8 42.4 185 11 6 6.8 3.7 13500 7.3 45.1 210 6 3 7.3 4.0 | 6.7 44.1 180 7 4 6.2 3.4 13000 8.3 46.9 225 5 2 6.8 3.7 | 7.5 45.5 180 4 2 5.9 3.2 12500 9.2 48.6 250 4 2 6.7 3.7 | 8.4 47.1 155 1 1 6.2 3.4 12000 10.2 50.4 275 3 2 6.6 3.6 | 9.4 48.9 030 2 1 6.7 3.7 11500 11.2 52.2 295 4 2 6.3 3.5 | 10.3 50.5 015 4 2 6.7 3.7 11000 12.0 53.6 310 4 2 5.6 3.1 | 11.3 52.3 015 6 3 6.6 3.6 10500 12.8 55.0 315 5 3 3.9 2.1 | 12.4 54.3 015 7 4 3.7 2.0 10250 13.0 55.4 315 6 3 3.4 1.9 | 12.5 54.5 015 7 4 4.5 2.5 10000 13.3 55.9 315 5 3 5.6 3.1 | 13.1 55.6 015 7 4 8.9 4.9 9750 13.6 56.5 310 5 3 5.5 3.0 | 13.7 56.7 020 7 4 8.2 4.5 9500 14.0 57.2 305 5 3 4.9 2.7 | 14.2 57.6 020 7 4 6.9 3.8 9250 14.2 57.6 295 5 2 3.8 2.1 | 14.6 58.3 025 6 3 4.6 2.5 9000 14.5 58.1 280 4 2 4.7 2.6 | 14.9 58.8 030 5 3 6.1 3.4 8750 14.9 58.8 260 4 2 5.5 3.0 | 15.3 59.5 045 4 2 7.0 3.9 8500 15.3 59.5 245 5 2 5.0 2.8 | 15.7 60.3 065 3 2 7.5 4.1 8250 15.7 60.3 235 5 3 4.8 2.6 | 16.2 61.2 075 3 2 8.0 4.4 8000 16.0 60.8 225 6 3 4.6 2.5 | 16.7 62.1 085 3 2 8.9 4.9 7750 16.3 61.3 220 6 3 4.3 2.4 | 17.4 63.3 090 3 2 10.2 5.6 7500 16.6 61.9 215 6 3 5.3 2.9 | 18.2 64.8 090 3 2 10.5 5.8 7250 17.0 62.6 205 6 3 6.4 3.5 | 19.0 66.2 090 3 2 11.0 6.0 7000 17.3 63.1 190 5 3 5.8 3.2 | 19.8 67.6 090 3 2 10.5 5.7 6750 17.6 63.7 175 5 3 6.8 3.7 | 20.5 68.9 090 3 2 9.9 5.4 6500 18.1 64.6 160 5 2 9.5 5.2 | 21.3 70.3 090 3 2 10.3 5.7 6250 18.9 66.0 160 4 2 11.3 6.2 | 22.1 71.8 090 3 2 11.8 6.5 6000 19.7 67.5 155 4 2 8.5 4.7 | 22.9 73.2 090 3 2 8.2 4.5 5750 20.3 68.5 155 4 2 12.7 7.0 | 23.5 74.3 090 3 2 14.8 8.1 5500 21.8 71.2 150 4 2 26.6 14.6 | 25.4 77.7 095 3 2 35.8 19.6 06/14/2024 at 1500 MDT | 06/14/2024 at 1800 MDT | CAPE... +1848.7 LI... -5.0 | CAPE... +4.4 LI... +0.2 CINH... -0.6 K Index... +32.9 | CINH... -69.9 K Index... +27.6 | 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 -58.0 -72.4 250 28 14 3.6 2.0 | -58.9 -74.0 265 29 15 2.9 1.6 45000 -55.0 -67.0 255 39 20 -1.5 -0.8 | -55.5 -67.9 275 21 11 0.8 0.4 40000 -56.1 -69.0 260 37 19 8.0 4.4 | -52.5 -62.5 085 30 15 9.0 4.9 38000 -51.4 -60.5 255 31 16 7.8 4.3 | -47.1 -52.8 080 25 13 8.9 4.9 36000 -46.7 -52.1 245 26 13 7.8 4.3 | -41.7 -43.1 075 20 10 8.9 4.9 34000 -41.5 -42.7 230 23 12 7.7 4.2 | -36.9 -34.4 075 14 7 8.0 4.4 32000 -36.9 -34.4 215 22 11 7.6 4.1 | -32.1 -25.8 075 8 4 7.8 4.3 30000 -31.8 -25.2 210 24 12 8.5 4.7 | -27.8 -18.0 095 3 2 7.2 3.9 29000 -29.3 -20.7 205 25 13 8.5 4.7 | -25.1 -13.2 180 2 1 7.2 4.0 28000 -26.8 -16.2 200 27 14 8.3 4.6 | -23.0 -9.4 220 4 2 6.7 3.7 27000 -24.3 -11.7 205 28 14 8.3 4.5 | -21.1 -6.0 225 6 3 6.6 3.6 26000 -21.9 -7.4 210 29 15 8.3 4.6 | -19.2 -2.6 230 9 4 6.6 3.6 25000 -19.4 -2.9 210 30 15 8.3 4.5 | -17.2 1.0 230 11 6 6.5 3.6 24000 -17.2 1.0 210 33 17 7.3 4.0 | -15.5 4.1 230 14 7 5.7 3.1 23000 -15.1 4.8 215 37 19 7.4 4.0 | -13.8 7.2 230 17 9 5.8 3.2 22000 -13.0 8.6 215 41 21 7.3 4.0 | -12.1 10.2 230 20 10 5.7 3.1 21000 -11.0 12.2 215 38 19 6.5 3.6 | -10.6 12.9 225 23 12 5.4 2.9 20000 -9.1 15.6 210 33 17 6.5 3.6 | -9.0 15.8 225 26 13 5.4 3.0 19500 -8.2 17.2 210 31 16 6.4 3.5 | -8.2 17.2 225 27 14 5.4 3.0 19000 -7.2 19.0 210 29 15 7.2 3.9 | -7.5 18.5 225 29 15 4.8 2.6 18500 -6.2 20.8 210 28 14 7.2 4.0 | -6.8 19.8 225 30 16 4.7 2.6 18000 -5.1 22.8 210 26 14 7.2 3.9 | -6.1 21.0 225 32 16 4.9 2.7 17500 -3.6 25.5 205 23 12 6.8 3.8 | -5.3 22.5 225 33 17 6.5 3.6 17000 -2.6 27.3 200 20 10 7.1 3.9 | -4.4 24.1 225 33 17 6.5 3.6 16500 -1.5 29.3 195 17 9 7.8 4.3 | -3.5 25.7 225 34 17 5.3 2.9 16000 -0.3 31.5 190 14 7 8.0 4.4 | -2.7 27.1 225 34 17 5.2 2.9 15500 0.7 33.3 185 10 5 5.9 3.2 | -1.5 29.3 225 34 17 7.2 3.9 15000 1.5 34.7 180 7 4 6.1 3.3 | -0.5 31.1 225 33 17 7.1 3.9 14500 2.4 36.3 170 4 2 6.3 3.4 | 0.6 33.1 230 33 17 8.0 4.4 14000 3.3 37.9 145 2 1 6.4 3.5 | 1.8 35.2 230 32 16 8.4 4.6 13500 4.1 39.4 065 2 1 7.1 3.9 | 3.1 37.6 230 31 16 8.9 4.9 13000 5.2 41.4 035 2 1 7.9 4.3 | 4.5 40.1 230 29 15 9.5 5.2 12500 6.3 43.3 025 4 2 8.3 4.5 | 5.9 42.6 235 28 14 9.2 5.1 12000 7.5 45.5 025 4 2 9.1 5.0 | 7.1 44.8 240 26 13 8.2 4.5 11500 8.7 47.7 030 4 2 9.2 5.1 | 8.3 46.9 240 24 12 8.0 4.4 11000 10.0 50.0 025 4 2 9.5 5.2 | 9.3 48.7 245 22 12 6.5 3.6 10500 11.4 52.5 025 5 3 6.1 3.3 | 10.2 50.4 255 21 11 4.9 2.7 10250 11.7 53.1 025 5 3 7.2 3.9 | 10.5 50.9 255 21 11 3.5 1.9 10000 12.6 54.7 020 5 3 12.5 6.9 | 10.8 51.4 260 20 10 6.2 3.4 9750 13.4 56.1 020 5 3 11.4 6.3 | 11.3 52.3 260 20 10 7.2 4.0 9500 14.3 57.7 020 5 3 10.5 5.8 | 11.8 53.2 265 20 10 6.3 3.5 9250 15.0 59.0 020 5 3 8.6 4.7 | 12.2 54.0 270 20 10 4.4 2.4 9000 15.6 60.1 015 5 3 9.7 5.3 | 12.5 54.5 270 20 10 3.6 2.0 8750 16.4 61.5 015 5 3 10.7 5.8 | 12.7 54.9 275 20 10 3.8 2.1 8500 17.2 63.0 010 5 3 10.2 5.6 | 13.0 55.4 275 20 10 3.8 2.1 8250 18.0 64.4 010 5 3 10.1 5.6 | 13.3 55.9 280 20 10 3.9 2.1 8000 18.7 65.7 005 6 3 9.8 5.4 | 13.5 56.3 280 20 11 3.7 2.0 7750 19.4 66.9 005 6 3 9.2 5.1 | 13.8 56.8 280 21 11 3.6 2.0 7500 20.1 68.2 005 6 3 10.0 5.5 | 14.0 57.2 280 21 11 2.7 1.5 7250 20.9 69.6 360 6 3 11.1 6.1 | 14.1 57.4 280 22 11 1.8 1.0 7000 21.7 71.1 360 6 3 10.2 5.6 | 14.3 57.7 280 22 11 2.1 1.2 6750 22.4 72.3 355 6 3 8.3 4.6 | 14.4 57.9 280 23 12 2.4 1.3 6500 23.1 73.6 355 6 3 9.7 5.3 | 14.5 58.1 275 22 12 0.9 0.5 6250 23.9 75.0 355 6 3 11.8 6.5 | 14.5 58.1 275 22 11 0.7 0.4 6000 24.7 76.5 355 6 3 10.1 5.5 | 14.4 57.9 270 21 11 -1.7 -1.0 5750 25.5 77.9 355 6 3 13.5 7.4 | 14.2 57.6 270 20 10 2.6 1.4 5500 26.9 80.4 350 6 3 24.0 13.2 | 15.0 59.0 260 16 8 19.6 10.7 ________________________________________________________________________________ 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