Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
283 UXUS97 KBOU 221309 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0709 MDT Sunday, September 22, 2024 This forecast is for Sunday, September 22, 2024: If the trigger temperature of 57.0 F/13.9 C is reached...then Thermal Soaring Index....................... Poor Maximum rate of lift........................ 0 ft/min (0.0 m/s) Maximum height of thermals.................. 10585 ft MSL (5308 ft AGL) Forecast maximum temperature................... 61.0 F/16.6 C Time of trigger temperature.................... 1445 MDT Time of overdevelopment........................ None Middle/high clouds during soaring window....... Broken/overcast opaque middle Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 8742 ft MSL (3465 ft AGL) Thermal soaring outlook for Monday 09/23....... 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 NVA Potential height of wave....................... 19806 ft MSL (14529 ft AGL) Wave soaring outlook for Monday 09/23.......... Poor Remarks... Low clouds and rain this morning, partial clearing in the afternoon. Sunrise/Sunset.................... 06:47:57 / 18:55:56 MDT Total possible sunshine........... 12 hr 7 min 59 sec (727 min 59 sec) Altitude of sun at 12:51:57 MDT... 50.09 degrees Upper air data from numerical model forecast valid on 09/22/2024 at 0600 MDT Freezing level.................. 10780 ft MSL (5503 ft AGL) Convective condensation level... 8592 ft MSL (3315 ft AGL) Lifted condensation level....... 9937 ft MSL (4660 ft AGL) Lifted index.................... +2.8 K index......................... +20.4 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 -58.1 -72.6 255 27 14 2.4 1.3 M M M M M 45000 -53.9 -65.0 245 32 16 3.9 2.1 M M M M M 40000 -48.1 -54.6 235 30 15 3.9 2.1 M M M M M 38000 -49.1 -56.4 235 12 6 -2.3 -1.2 M M M M M 36000 -50.5 -58.9 055 9 4 -2.3 -1.2 M M M M M 34000 -48.8 -55.8 055 19 10 8.5 4.7 M M M M M 32000 -43.7 -46.7 060 19 10 8.5 4.7 M M M M M 30000 -37.8 -36.0 065 16 8 8.9 4.9 38.3 100.9 16.7 M M 29000 -35.1 -31.2 070 15 8 8.9 4.9 37.9 100.2 16.6 M M 28000 -32.5 -26.5 080 13 7 8.9 4.9 37.7 99.8 16.6 M M 27000 -30.1 -22.2 085 12 6 7.8 4.3 37.1 98.7 16.3 M M 26000 -27.7 -17.9 095 10 5 7.8 4.3 36.2 97.2 15.9 M M 25000 -25.4 -13.7 105 9 5 7.8 4.3 35.6 96.0 15.5 M M 24000 -23.2 -9.8 115 8 4 7.1 3.9 34.7 94.5 15.0 M M 23000 -21.1 -6.0 130 7 4 7.1 3.9 33.7 92.7 14.3 M M 22000 -19.0 -2.2 150 6 3 7.1 3.9 32.8 91.1 13.7 M M 21000 -17.0 1.4 165 6 3 6.6 3.6 31.8 89.2 12.9 M M 20000 -15.0 5.0 180 5 3 6.6 3.6 30.6 87.1 12.1 M M 19500 -14.0 6.8 185 5 3 6.6 3.6 30.1 86.2 11.7 M M 19000 -13.1 8.4 195 5 3 6.7 3.7 29.6 85.3 11.3 M M 18500 -12.1 10.2 205 5 3 6.7 3.7 29.1 84.4 10.9 M M 18000 -11.1 12.0 215 6 3 6.7 3.7 28.6 83.4 10.5 M M 17500 -10.1 13.8 225 6 3 6.6 3.6 28.0 82.5 10.1 M M 17000 -9.1 15.6 235 6 3 6.5 3.6 27.5 81.5 9.6 M M 16500 -8.2 17.2 240 7 3 6.3 3.5 26.9 80.5 9.2 M M 16000 -7.3 18.9 240 7 3 5.7 3.1 26.3 79.3 8.6 M M 15500 -6.5 20.3 240 6 3 5.9 3.2 25.6 78.1 8.0 M M 15000 -5.6 21.9 230 6 3 4.3 2.4 24.3 75.8 6.8 M M 14500 -5.0 23.0 220 5 3 4.9 2.7 23.4 74.1 5.9 M M 14000 -4.1 24.6 215 6 3 6.6 3.6 22.8 73.0 5.4 M M 13500 -3.2 26.2 215 6 3 6.4 3.5 22.3 72.1 4.9 M M 13000 -2.4 27.7 225 6 3 4.3 2.4 21.5 70.8 4.2 M M 12500 -1.8 28.8 240 6 3 4.5 2.5 20.7 69.2 3.4 M M 12000 -1.2 29.8 255 6 3 3.4 1.9 19.7 67.5 2.6 M M 11500 -0.7 30.7 265 6 3 3.5 1.9 18.7 65.7 1.6 M M 11000 -0.2 31.6 270 6 3 3.7 2.0 17.7 63.9 0.7 M M 10500 0.3 32.5 270 4 2 3.7 2.0 16.8 62.2 -0.3 362 1.8 10250 0.5 32.9 265 3 2 0.8 0.5 16.2 61.2 -0.8 349 1.8 10000 0.6 33.1 265 3 1 3.7 2.0 15.5 60.0 -1.5 340 1.7 9750 1.1 34.0 265 2 1 8.6 4.7 15.3 59.6 -1.7 317 1.6 9500 1.7 35.1 250 1 1 6.7 3.7 15.2 59.3 -1.9 293 1.5 9250 2.1 35.8 000 0 0 4.4 2.4 14.8 58.7 -2.2 274 1.4 9000 2.3 36.1 160 1 0 4.1 2.2 14.4 57.9 -2.7 258 1.3 8750 2.7 36.9 130 1 1 6.2 3.4 14.0 57.2 -3.0 240 1.2 8500 3.2 37.8 120 2 1 5.9 3.2 13.8 56.8 -3.3 219 1.1 8250 3.5 38.3 115 3 1 4.7 2.6 13.4 56.1 -3.7 200 1.0 8000 3.9 39.0 110 4 2 4.9 2.7 13.0 55.4 -4.1 183 0.9 7750 4.2 39.6 110 4 2 6.1 3.4 12.7 54.8 -4.4 164 0.8 7500 4.7 40.5 105 6 3 5.5 3.0 12.4 54.4 -4.7 143 0.7 7250 5.0 41.0 100 7 4 4.3 2.4 12.0 53.6 -5.2 126 0.6 7000 5.3 41.5 095 8 4 4.1 2.3 11.6 52.9 -5.6 109 0.6 6750 5.7 42.3 090 10 5 6.2 3.4 11.2 52.2 -6.0 92 0.5 6500 6.2 43.2 085 10 5 9.0 4.9 11.1 52.0 -6.2 68 0.3 6250 6.8 44.2 080 10 5 8.8 4.8 11.0 51.8 -6.3 42 0.2 6000 7.5 45.5 075 10 5 8.9 4.9 10.9 51.7 -6.4 16 0.1 5750 8.2 46.8 070 10 5 11.2 6.1 10.9 51.7 -6.5 M M 5500 9.1 48.4 070 9 4 14.9 8.2 11.2 52.2 -6.3 M M * * * * * * Numerical weather prediction model forecast data valid * * * * * * 09/22/2024 at 0900 MDT | 09/22/2024 at 1200 MDT | CAPE... +30.4 LI... +4.3 | CAPE... +23.1 LI... +4.2 CINH... -0.0 K Index... +18.4 | CINH... 0.0 K Index... +18.8 | 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 -58.1 -72.6 265 21 11 2.0 1.1 | -58.0 -72.4 265 18 9 2.7 1.5 45000 -54.7 -66.5 255 26 13 3.1 1.7 | -53.9 -65.0 260 23 12 3.0 1.7 40000 -50.0 -58.0 260 26 13 3.0 1.6 | -49.3 -56.7 275 23 12 3.0 1.6 38000 -50.5 -58.9 275 11 6 -1.3 -0.7 | -50.2 -58.4 285 11 6 -2.0 -1.1 36000 -51.3 -60.3 035 9 5 -1.3 -0.7 | -51.4 -60.5 035 5 2 -2.0 -1.1 34000 -49.2 -56.6 055 17 9 8.4 4.6 | -49.3 -56.7 060 11 5 9.1 5.0 32000 -44.1 -47.4 055 17 9 8.4 4.6 | -43.1 -45.6 055 11 6 9.1 5.0 30000 -38.1 -36.6 060 17 9 9.4 5.2 | -37.7 -35.9 045 11 6 9.0 4.9 29000 -35.3 -31.5 065 17 9 9.4 5.2 | -35.0 -31.0 040 12 6 9.0 4.9 28000 -32.5 -26.5 070 17 9 9.5 5.2 | -32.3 -26.1 030 12 6 9.1 5.0 27000 -29.9 -21.8 070 15 8 8.3 4.6 | -29.8 -21.6 025 11 6 8.0 4.4 26000 -27.4 -17.3 075 12 6 8.3 4.6 | -27.4 -17.3 020 9 5 8.0 4.4 25000 -24.9 -12.8 085 9 5 8.3 4.6 | -25.0 -13.0 010 8 4 8.0 4.4 24000 -22.5 -8.5 095 8 4 7.6 4.2 | -22.7 -8.9 010 7 4 7.7 4.2 23000 -20.2 -4.4 100 6 3 7.6 4.2 | -20.4 -4.7 015 7 3 7.7 4.2 22000 -18.0 -0.4 110 5 2 7.7 4.2 | -18.1 -0.6 020 6 3 7.7 4.2 21000 -16.0 3.2 105 3 2 6.2 3.4 | -16.0 3.2 030 6 3 6.9 3.8 20000 -14.1 6.6 065 2 1 6.2 3.4 | -14.0 6.8 045 7 4 6.9 3.8 19500 -13.2 8.2 040 2 1 6.2 3.4 | -12.9 8.8 055 7 4 6.9 3.8 19000 -12.3 9.9 020 3 1 6.0 3.3 | -11.9 10.6 060 8 4 6.6 3.6 18500 -11.5 11.3 010 3 2 5.2 2.8 | -11.1 12.0 060 8 4 5.7 3.1 18000 -10.8 12.6 360 4 2 5.2 2.8 | -10.3 13.5 065 9 5 5.7 3.1 17500 -10.0 14.0 350 5 2 6.2 3.4 | -9.4 15.1 065 10 5 6.5 3.6 17000 -9.0 15.8 335 5 3 6.3 3.5 | -8.4 16.9 065 11 6 6.5 3.6 16500 -8.1 17.4 325 6 3 6.3 3.5 | -7.5 18.5 065 12 6 6.2 3.4 16000 -7.2 19.0 325 7 3 6.3 3.5 | -6.7 19.9 060 11 6 5.6 3.1 15500 -6.3 20.7 320 7 4 6.3 3.5 | -5.4 22.3 055 10 5 5.3 2.9 15000 -5.6 21.9 320 7 4 3.4 1.9 | -4.7 23.5 050 9 5 5.1 2.8 14500 -4.9 23.2 315 6 3 3.3 1.8 | -3.9 25.0 045 8 4 4.8 2.6 14000 -4.5 23.9 300 6 3 2.6 1.4 | -3.3 26.1 035 6 3 4.2 2.3 13500 -4.1 24.6 285 5 3 3.2 1.8 | -2.7 27.1 010 5 2 4.2 2.3 13000 -3.4 25.9 275 5 3 6.8 3.7 | -2.1 28.2 340 3 2 4.4 2.4 12500 -2.4 27.7 275 5 3 6.4 3.5 | -1.4 29.5 295 3 2 4.4 2.4 12000 -1.7 28.9 285 5 3 3.7 2.0 | -0.7 30.7 290 4 2 5.0 2.7 11500 -1.2 29.8 300 6 3 3.8 2.1 | -0.0 32.0 300 3 2 4.7 2.6 11000 -0.7 30.7 305 5 3 2.9 1.6 | 0.1 32.2 280 4 2 -1.6 -0.9 10500 -0.3 31.5 310 5 3 3.0 1.7 | -0.1 31.8 255 6 3 -0.5 -0.3 10250 -0.1 31.8 310 5 2 1.3 0.7 | -0.1 31.8 255 7 3 0.3 0.1 10000 0.0 32.0 320 4 2 4.6 2.5 | 0.0 32.0 255 6 3 5.1 2.8 9750 0.6 33.1 340 4 2 9.5 5.2 | 0.6 33.1 260 5 2 9.7 5.3 9500 1.2 34.2 360 4 2 7.2 3.9 | 1.2 34.2 275 3 2 7.2 4.0 9250 1.6 34.9 005 4 2 4.4 2.4 | 1.6 34.9 285 2 1 4.1 2.2 9000 1.9 35.4 010 4 2 4.5 2.5 | 1.9 35.4 295 2 1 4.3 2.3 8750 2.3 36.1 015 4 2 6.4 3.5 | 2.3 36.1 295 1 1 7.3 4.0 8500 2.8 37.0 025 3 2 5.7 3.1 | 2.9 37.2 295 1 0 6.6 3.6 8250 3.1 37.6 035 4 2 4.2 2.3 | 3.2 37.8 000 0 0 4.8 2.6 8000 3.4 38.1 045 4 2 4.6 2.5 | 3.6 38.5 160 1 1 5.3 2.9 7750 3.8 38.8 055 4 2 6.0 3.3 | 4.0 39.2 155 2 1 7.3 4.0 7500 4.3 39.7 065 5 3 6.2 3.4 | 4.6 40.3 145 3 1 9.1 5.0 7250 4.6 40.3 070 6 3 5.5 3.0 | 5.3 41.5 135 3 2 8.6 4.7 7000 5.0 41.0 075 8 4 5.1 2.8 | 5.9 42.6 130 4 2 9.4 5.2 6750 5.4 41.7 080 9 4 7.1 3.9 | 6.6 43.9 125 5 3 10.5 5.7 6500 6.1 43.0 075 9 5 9.3 5.1 | 7.4 45.3 125 5 3 10.2 5.6 6250 6.7 44.1 075 9 5 8.9 4.9 | 8.2 46.8 125 5 3 10.5 5.8 6000 7.3 45.1 070 9 5 8.5 4.6 | 8.9 48.0 125 5 3 9.0 5.0 5750 8.0 46.4 070 9 4 10.8 5.9 | 9.7 49.5 125 5 2 12.8 7.0 5500 9.0 48.2 070 8 4 16.7 9.2 | 11.0 51.8 120 5 2 23.4 12.8 09/22/2024 at 1500 MDT | 09/22/2024 at 1800 MDT | CAPE... +4.3 LI... +3.8 | CAPE... +0.7 LI... +3.0 CINH... -0.1 K Index... +19.0 | CINH... 0.0 K Index... +14.2 | 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 -58.7 -73.7 265 22 11 1.9 1.1 | -58.6 -73.5 265 23 12 2.2 1.2 45000 -55.2 -67.4 265 25 13 3.4 1.9 | -54.9 -66.8 260 26 14 3.1 1.7 40000 -50.1 -58.2 280 23 12 2.7 1.5 | -50.2 -58.4 270 23 12 2.5 1.4 38000 -50.5 -58.9 290 16 8 -1.0 -0.5 | -50.3 -58.5 285 16 8 -0.5 -0.3 36000 -51.1 -60.0 315 9 4 -1.0 -0.5 | -50.7 -59.3 310 11 5 -0.5 -0.3 34000 -48.7 -55.7 355 7 4 8.6 4.7 | -48.2 -54.8 335 9 5 8.1 4.5 32000 -43.6 -46.5 015 9 4 8.6 4.7 | -43.3 -45.9 340 9 5 8.1 4.5 30000 -37.5 -35.5 015 10 5 9.2 5.1 | -37.4 -35.3 335 10 5 9.2 5.0 29000 -34.8 -30.6 010 11 6 9.2 5.1 | -34.7 -30.5 330 12 6 9.2 5.0 28000 -32.0 -25.6 010 12 6 9.3 5.1 | -31.9 -25.4 330 13 7 9.3 5.1 27000 -29.5 -21.1 010 12 6 8.2 4.5 | -29.3 -20.7 330 13 7 8.7 4.7 26000 -27.0 -16.6 010 13 7 8.3 4.5 | -26.7 -16.1 330 14 7 8.7 4.8 25000 -24.6 -12.3 010 13 7 8.3 4.5 | -24.1 -11.4 335 14 7 8.6 4.7 24000 -22.2 -8.0 010 13 7 7.4 4.1 | -21.7 -7.1 340 13 7 7.3 4.0 23000 -20.0 -4.0 015 12 6 7.4 4.1 | -19.6 -3.3 355 11 6 7.3 4.0 22000 -17.9 -0.2 020 11 6 7.4 4.1 | -17.4 0.7 010 10 5 7.3 4.0 21000 -15.7 3.7 030 10 5 7.1 3.9 | -15.4 4.3 025 10 5 6.8 3.7 20000 -13.6 7.5 040 10 5 7.1 3.9 | -13.4 7.9 035 9 5 6.8 3.7 19500 -12.6 9.3 045 9 5 7.1 3.9 | -12.4 9.7 040 9 5 6.8 3.7 19000 -11.6 11.1 050 9 5 6.9 3.8 | -11.4 11.5 045 9 5 6.9 3.8 18500 -10.6 12.9 055 9 4 6.3 3.5 | -10.3 13.5 045 9 5 7.2 3.9 18000 -9.7 14.5 060 8 4 6.4 3.5 | -9.2 15.4 045 9 5 7.2 4.0 17500 -8.8 16.2 065 8 4 6.3 3.5 | -8.2 17.2 045 10 5 6.4 3.5 17000 -7.9 17.8 070 9 4 6.3 3.5 | -7.3 18.9 045 9 5 6.4 3.5 16500 -6.9 19.6 075 9 5 6.3 3.4 | -6.3 20.7 045 9 5 6.2 3.4 16000 -5.6 21.9 080 10 5 6.2 3.4 | -5.5 22.1 045 10 5 5.9 3.2 15500 -4.7 23.5 080 11 6 5.6 3.1 | -4.2 24.4 050 10 5 7.0 3.8 15000 -4.0 24.8 080 10 5 5.3 2.9 | -3.1 26.4 060 10 5 7.6 4.2 14500 -3.3 26.1 080 9 4 5.0 2.7 | -2.0 28.4 065 11 6 7.2 3.9 14000 -2.6 27.3 070 6 3 4.4 2.4 | -1.1 30.0 060 10 5 6.1 3.4 13500 -2.0 28.4 045 4 2 4.5 2.5 | -0.2 31.6 055 9 5 6.0 3.3 13000 -1.2 29.8 350 3 2 5.2 2.8 | 0.5 32.9 040 8 4 4.5 2.5 12500 -0.4 31.3 315 5 3 5.1 2.8 | 1.1 34.0 020 8 4 4.6 2.5 12000 0.4 32.7 300 6 3 5.5 3.0 | 1.8 35.2 360 8 4 5.1 2.8 11500 1.2 34.2 290 7 4 5.4 3.0 | 2.6 36.7 350 9 5 5.3 2.9 11000 1.8 35.2 285 7 3 3.6 2.0 | 3.1 37.6 340 8 4 1.5 0.8 10500 2.4 36.3 285 6 3 3.6 2.0 | 3.4 38.1 335 6 3 1.9 1.0 10250 2.6 36.7 280 6 3 1.1 0.6 | 3.5 38.3 330 5 3 0.7 0.4 10000 2.6 36.7 275 5 3 0.5 0.3 | 3.5 38.3 325 4 2 0.9 0.5 9750 2.6 36.7 260 5 2 1.4 0.7 | 3.5 38.3 285 2 1 1.8 1.0 9500 2.7 36.9 240 5 2 2.2 1.2 | 3.6 38.5 195 3 1 2.4 1.3 9250 2.9 37.2 220 4 2 4.7 2.6 | 3.8 38.8 180 4 2 5.9 3.3 9000 3.3 37.9 200 4 2 6.6 3.6 | 4.4 39.9 180 5 2 8.8 4.9 8750 3.8 38.8 180 4 2 7.8 4.3 | 5.1 41.2 180 5 2 9.9 5.5 8500 4.4 39.9 160 4 2 8.2 4.5 | 5.8 42.4 180 5 2 9.7 5.3 8250 5.0 41.0 155 4 2 8.3 4.5 | 6.5 43.7 180 5 2 8.9 4.9 8000 5.6 42.1 150 4 2 8.6 4.7 | 7.1 44.8 180 4 2 9.0 5.0 7750 6.2 43.2 150 4 2 10.2 5.6 | 7.8 46.0 175 4 2 9.8 5.4 7500 7.0 44.6 150 4 2 10.6 5.8 | 8.6 47.5 175 4 2 10.1 5.6 7250 7.8 46.0 150 4 2 9.9 5.4 | 9.3 48.7 175 4 2 10.1 5.5 7000 8.5 47.3 150 4 2 10.2 5.6 | 10.1 50.2 175 4 2 10.0 5.5 6750 9.3 48.7 150 4 2 10.9 6.0 | 10.8 51.4 175 4 2 9.6 5.3 6500 10.1 50.2 150 4 2 10.7 5.9 | 11.6 52.9 175 4 2 9.9 5.4 6250 10.9 51.6 150 4 2 10.0 5.5 | 12.3 54.1 175 4 2 10.1 5.5 6000 11.7 53.1 150 4 2 10.6 5.8 | 13.1 55.6 175 4 2 10.6 5.8 5750 12.6 54.7 150 4 2 16.9 9.3 | 13.9 57.0 175 3 2 12.7 7.0 5500 14.3 57.7 145 4 2 25.9 14.2 | 14.9 58.8 175 3 2 14.0 7.7 ________________________________________________________________________________ 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