Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
175 UXUS97 KBOU 311319 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0718 MDT Thursday, October 31, 2024 This forecast is for Thursday, October 31, 2024: If the trigger temperature of 47.3 F/8.5 C is reached...then Thermal Soaring Index....................... Good Maximum rate of lift........................ 618 ft/min (3.1 m/s) Maximum height of thermals.................. 13690 ft MSL (8376 ft AGL) Forecast maximum temperature................... 59.0 F/15.5 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................. 11683 ft MSL (6369 ft AGL) Thermal soaring outlook for Friday 11/01....... Fair 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....................... 38497 ft MSL (33183 ft AGL) Wave soaring outlook for Friday 11/01.......... Good Remarks... Sunrise/Sunset.................... 07:27:58 / 17:58:03 MDT Total possible sunshine........... 10 hr 30 min 5 sec (630 min 5 sec) Altitude of sun at 12:43:01 MDT... 35.64 degrees Upper air data from numerical model forecast valid on 10/31/2024 at 0600 MDT Freezing level.................. 7634 ft MSL (2320 ft AGL) Convective condensation level... 16199 ft MSL (10885 ft AGL) Lifted condensation level....... 14944 ft MSL (9630 ft AGL) Lifted index.................... +5.6 K index......................... -14.4 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 -57.5 -71.5 240 50 26 3.3 1.8 M M M M M 45000 -52.6 -62.7 245 66 34 -0.5 -0.3 M M M M M 40000 -53.4 -64.1 255 72 37 -0.6 -0.3 M M M M M 38000 -53.5 -64.3 260 72 37 0.5 0.3 M M M M M 36000 -53.1 -63.6 260 70 36 0.5 0.3 M M M M M 34000 -52.5 -62.5 260 67 34 6.6 3.6 M M M M M 32000 -48.4 -55.1 265 65 33 6.8 3.8 M M M M M 30000 -43.6 -46.5 270 62 32 7.9 4.3 32.7 90.8 13.2 M M 29000 -41.3 -42.3 270 61 32 7.9 4.3 31.8 89.3 12.8 M M 28000 -38.9 -38.0 270 60 31 7.9 4.3 31.1 88.0 12.4 M M 27000 -36.5 -33.7 270 59 31 7.7 4.2 30.6 87.0 12.1 M M 26000 -34.3 -29.7 275 58 30 7.3 4.0 29.5 85.1 11.4 M M 25000 -32.2 -26.0 275 56 29 7.3 4.0 28.6 83.5 10.8 M M 24000 -30.0 -22.0 275 55 28 7.3 4.0 27.8 82.0 10.3 M M 23000 -27.8 -18.0 280 52 27 7.2 3.9 26.8 80.2 9.6 M M 22000 -25.7 -14.3 280 50 26 7.2 3.9 25.8 78.5 8.9 M M 21000 -23.5 -10.3 280 48 25 7.0 3.8 25.0 77.0 8.3 M M 20000 -21.5 -6.7 285 45 23 6.7 3.7 23.8 74.9 7.4 M M 19500 -20.5 -4.9 285 44 23 6.7 3.7 23.3 73.9 7.0 M M 19000 -19.5 -3.1 285 42 22 6.7 3.7 22.8 73.0 6.6 M M 18500 -18.5 -1.3 285 41 21 6.6 3.6 22.3 72.1 6.3 M M 18000 -17.6 0.3 285 39 20 5.9 3.2 21.7 71.0 5.8 M M 17500 -16.7 1.9 285 38 20 6.0 3.3 21.0 69.8 5.2 M M 17000 -15.8 3.6 290 37 19 5.5 3.0 20.3 68.6 4.7 M M 16500 -15.0 5.0 290 35 18 5.4 3.0 19.6 67.3 4.0 M M 16000 -13.8 7.2 290 33 17 5.2 2.8 18.5 65.3 3.1 M M 15500 -13.0 8.6 290 32 17 5.2 2.9 17.7 63.9 2.4 M M 15000 -12.3 9.9 290 31 16 5.2 2.8 17.0 62.6 1.7 M M 14500 -11.5 11.3 290 30 15 5.2 2.8 16.2 61.2 1.0 M M 14000 -10.7 12.7 290 29 15 5.1 2.8 15.5 59.8 0.3 M M 13500 -10.0 14.0 290 28 14 5.0 2.7 14.7 58.4 -0.4 599 3.0 13000 -9.3 15.3 285 27 14 5.0 2.7 13.9 57.0 -1.1 562 2.9 12500 -8.5 16.7 285 25 13 5.1 2.8 13.1 55.6 -1.9 525 2.7 12000 -7.8 18.0 285 24 12 5.2 2.8 12.4 54.3 -2.6 489 2.5 11500 -7.0 19.4 285 23 12 5.3 2.9 11.6 52.9 -3.3 451 2.3 11000 -6.3 20.7 280 23 12 5.5 3.0 10.9 51.7 -4.0 413 2.1 10500 -5.4 22.3 280 21 11 5.9 3.2 10.3 50.5 -4.7 373 1.9 10250 -5.0 23.0 280 21 11 5.4 3.0 10.0 50.0 -5.0 353 1.8 10000 -4.7 23.5 280 20 10 3.5 1.9 9.6 49.3 -5.4 336 1.7 9750 -4.4 24.1 280 20 10 5.5 3.0 9.1 48.4 -5.9 320 1.6 9500 -3.9 25.0 280 18 10 8.2 4.5 8.9 48.1 -6.1 297 1.5 9250 -3.3 26.1 280 17 9 6.9 3.8 8.8 47.8 -6.3 273 1.4 9000 -2.9 26.8 275 16 8 5.4 3.0 8.5 47.3 -6.6 252 1.3 8750 -2.5 27.5 275 15 8 6.8 3.7 8.2 46.7 -6.9 233 1.2 8500 -1.9 28.6 275 13 7 8.9 4.9 8.0 46.5 -7.1 207 1.1 8250 -1.3 29.7 270 11 6 7.3 4.0 7.9 46.3 -7.2 181 0.9 8000 -0.8 30.6 265 10 5 5.5 3.0 7.7 45.8 -7.5 160 0.8 7750 -0.4 31.3 265 10 5 7.5 4.1 7.4 45.3 -7.8 140 0.7 7500 0.3 32.5 255 8 4 8.9 4.9 7.3 45.1 -7.9 113 0.6 7250 0.9 33.6 250 7 4 6.4 3.5 7.1 44.8 -8.1 89 0.5 7000 1.2 34.2 245 7 4 4.5 2.5 6.8 44.2 -8.5 70 0.4 6750 1.6 34.9 240 7 4 7.2 4.0 6.5 43.6 -8.8 51 0.3 6500 2.2 36.0 225 7 4 5.3 2.9 6.3 43.3 -9.0 27 0.1 6250 2.3 36.1 215 7 4 0.5 0.3 5.7 42.3 -9.7 16 0.1 6000 2.4 36.3 210 7 4 2.5 1.4 5.1 41.1 -10.4 6 0.0 5750 2.5 36.5 205 7 4 -3.0 -1.7 4.4 40.0 -11.0 M M 5500 1.6 34.9 195 7 4 -19.6 -10.7 2.9 37.2 -12.6 14 0.1 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 10/31/2024 at 0900 MDT | 10/31/2024 at 1200 MDT | CAPE... 0.0 LI... +8.2 | CAPE... 0.0 LI... +7.2 CINH... -0.1 K Index... -9.3 | CINH... -0.1 K Index... -0.3 | 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 -56.9 -70.4 245 47 24 2.3 1.2 | -57.4 -71.3 245 47 24 2.2 1.2 45000 -53.4 -64.1 250 65 34 0.2 0.1 | -54.0 -65.2 250 70 36 -0.7 -0.4 40000 -53.6 -64.5 255 71 36 -0.1 -0.1 | -56.0 -68.8 255 76 39 -1.3 -0.7 38000 -53.7 -64.7 260 70 36 -0.2 -0.1 | -55.9 -68.6 260 77 40 1.6 0.9 36000 -53.8 -64.8 260 66 34 -0.2 -0.1 | -55.0 -67.0 265 76 39 1.6 0.9 34000 -53.5 -64.3 265 62 32 6.8 3.7 | -53.4 -64.1 265 75 39 8.8 4.8 32000 -49.6 -57.3 265 61 31 6.5 3.6 | -48.6 -55.5 265 74 38 8.2 4.5 30000 -44.8 -48.6 265 59 30 8.7 4.8 | -43.1 -45.6 260 71 36 7.9 4.3 29000 -42.2 -44.0 265 57 29 8.7 4.8 | -40.7 -41.3 260 67 34 7.9 4.3 28000 -39.6 -39.3 270 56 29 8.7 4.8 | -38.4 -37.1 260 63 32 7.9 4.3 27000 -37.0 -34.6 270 54 28 8.3 4.6 | -36.0 -32.8 265 59 30 7.8 4.3 26000 -34.6 -30.3 270 52 27 8.0 4.4 | -33.7 -28.7 260 55 28 7.7 4.2 25000 -32.2 -26.0 270 50 26 8.0 4.4 | -31.4 -24.5 260 51 26 7.7 4.2 24000 -29.8 -21.6 270 48 25 7.9 4.3 | -29.1 -20.4 260 47 24 7.6 4.2 23000 -27.6 -17.7 270 45 23 7.5 4.1 | -26.9 -16.4 260 44 23 7.5 4.1 22000 -25.3 -13.5 275 42 22 7.5 4.1 | -24.6 -12.3 260 41 21 7.5 4.1 21000 -23.1 -9.6 275 40 20 7.2 3.9 | -22.4 -8.3 260 38 19 7.1 3.9 20000 -21.0 -5.8 275 38 19 7.0 3.8 | -20.3 -4.5 260 35 18 6.9 3.8 19500 -20.0 -4.0 280 37 19 7.0 3.8 | -19.3 -2.7 260 34 17 7.0 3.8 19000 -18.9 -2.0 280 36 18 6.9 3.8 | -18.3 -0.9 260 33 17 6.9 3.8 18500 -17.9 -0.2 280 35 18 6.8 3.7 | -17.2 1.0 265 31 16 6.8 3.8 18000 -16.9 1.6 280 34 17 6.4 3.5 | -16.2 2.8 265 31 16 6.7 3.7 17500 -16.0 3.2 285 33 17 6.4 3.5 | -15.2 4.6 270 31 16 6.9 3.8 17000 -15.0 5.0 285 32 17 6.2 3.4 | -14.3 6.3 270 31 16 5.3 2.9 16500 -13.6 7.5 290 32 16 6.2 3.4 | -13.6 7.5 270 30 16 5.4 3.0 16000 -12.7 9.1 290 32 16 5.7 3.1 | -12.7 9.1 275 30 15 5.7 3.1 15500 -11.9 10.6 290 31 16 5.8 3.2 | -11.5 11.3 275 29 15 5.9 3.2 15000 -11.0 12.2 290 31 16 5.4 3.0 | -10.6 12.9 280 28 14 5.4 3.0 14500 -10.2 13.6 290 30 15 5.4 3.0 | -9.8 14.4 280 27 14 5.4 3.0 14000 -9.4 15.1 290 29 15 5.4 3.0 | -9.0 15.8 280 26 13 5.7 3.1 13500 -8.6 16.5 290 28 14 5.4 3.0 | -8.1 17.4 280 24 12 5.8 3.2 13000 -7.8 18.0 290 27 14 5.4 3.0 | -7.3 18.9 280 22 11 6.0 3.3 12500 -7.0 19.4 290 26 13 5.4 3.0 | -6.3 20.7 280 20 11 6.2 3.4 12000 -6.2 20.8 290 25 13 5.2 2.8 | -5.4 22.3 275 19 10 6.3 3.5 11500 -5.5 22.1 285 24 12 4.9 2.7 | -4.4 24.1 275 17 9 6.4 3.5 11000 -4.8 23.4 285 23 12 5.1 2.8 | -3.5 25.7 270 16 8 6.6 3.6 10500 -4.0 24.8 285 21 11 5.4 3.0 | -2.5 27.5 265 14 7 7.5 4.1 10250 -3.6 25.5 280 20 10 4.0 2.2 | -2.0 28.4 265 14 7 3.0 1.6 10000 -3.4 25.9 280 20 11 3.5 1.9 | -1.9 28.6 265 14 7 3.6 2.0 9750 -3.0 26.6 280 19 10 5.9 3.3 | -1.4 29.5 260 13 7 8.4 4.6 9500 -2.6 27.3 275 17 9 7.1 3.9 | -0.8 30.6 255 11 6 7.4 4.1 9250 -2.1 28.2 275 15 8 5.9 3.2 | -0.3 31.5 245 10 5 6.4 3.5 9000 -1.7 28.9 270 14 7 4.3 2.3 | 0.1 32.2 240 10 5 4.2 2.3 8750 -1.4 29.5 265 13 7 5.6 3.1 | 0.5 32.9 230 9 5 5.4 3.0 8500 -0.9 30.4 260 11 6 7.1 3.9 | 0.9 33.6 220 8 4 6.6 3.6 8250 -0.4 31.3 250 9 5 6.0 3.3 | 1.4 34.5 210 8 4 5.7 3.1 8000 -0.0 32.0 240 8 4 5.0 2.8 | 1.8 35.2 200 8 4 5.0 2.8 7750 0.4 32.7 235 8 4 6.2 3.4 | 2.2 36.0 190 8 4 6.5 3.6 7500 0.9 33.6 225 7 4 6.7 3.7 | 2.7 36.9 185 8 4 7.4 4.1 7250 1.3 34.3 215 7 4 5.7 3.1 | 3.2 37.8 185 8 4 7.1 3.9 7000 1.7 35.1 215 7 4 4.8 2.6 | 3.7 38.7 185 8 4 5.9 3.2 6750 2.1 35.8 210 7 3 6.7 3.7 | 4.2 39.6 180 8 4 11.0 6.0 6500 2.6 36.7 205 7 3 4.8 2.6 | 5.3 41.5 180 7 4 12.8 7.0 6250 2.8 37.0 200 7 4 1.8 1.0 | 6.0 42.8 180 7 4 9.2 5.1 6000 2.9 37.2 200 7 4 2.4 1.3 | 6.7 44.1 180 7 4 8.9 4.9 5750 3.1 37.6 195 7 4 2.8 1.6 | 7.4 45.3 180 7 4 12.3 6.7 5500 3.3 37.9 200 7 3 2.0 1.1 | 8.7 47.7 180 6 3 22.2 12.2 10/31/2024 at 1500 MDT | 10/31/2024 at 1800 MDT | CAPE... 0.0 LI... +6.1 | CAPE... 0.0 LI... +3.5 CINH... 0.0 K Index... +4.8 | CINH... 0.0 K Index... +8.3 | 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 -58.5 -73.3 245 48 24 0.8 0.4 | -59.7 -75.5 250 48 25 0.1 0.1 45000 -57.3 -71.1 250 67 34 0.3 0.2 | -59.5 -75.1 255 60 31 1.0 0.5 40000 -58.5 -73.3 255 83 43 -0.8 -0.4 | -57.4 -71.3 260 78 40 1.4 0.8 38000 -57.4 -71.3 260 85 44 4.0 2.2 | -56.0 -68.8 260 83 43 3.0 1.6 36000 -55.0 -67.0 260 84 43 4.0 2.2 | -54.0 -65.2 260 86 44 3.0 1.6 34000 -52.2 -62.0 265 83 43 8.1 4.4 | -51.4 -60.5 260 87 45 7.7 4.2 32000 -47.4 -53.3 260 77 40 7.9 4.4 | -46.7 -52.1 260 81 41 7.8 4.3 30000 -42.6 -44.7 260 72 37 8.2 4.5 | -41.9 -43.4 260 75 39 8.4 4.6 29000 -39.6 -39.3 260 71 37 8.2 4.5 | -39.4 -38.9 260 73 38 8.4 4.6 28000 -37.1 -34.8 260 70 36 8.2 4.5 | -36.9 -34.4 265 71 37 8.4 4.6 27000 -34.7 -30.5 260 69 35 7.2 3.9 | -34.3 -29.7 265 69 36 8.3 4.5 26000 -32.6 -26.7 260 65 34 6.9 3.8 | -31.9 -25.4 265 68 35 8.1 4.5 25000 -30.6 -23.1 260 62 32 6.9 3.8 | -29.4 -20.9 265 67 34 8.1 4.5 24000 -28.5 -19.3 260 59 30 6.9 3.8 | -27.0 -16.6 265 65 34 7.7 4.2 23000 -26.5 -15.7 260 55 28 7.0 3.8 | -25.1 -13.2 265 64 33 5.9 3.2 22000 -24.4 -11.9 260 51 26 7.0 3.8 | -23.4 -10.1 265 62 32 5.9 3.3 21000 -22.3 -8.1 260 48 25 7.5 4.1 | -21.6 -6.9 265 60 31 5.4 2.9 20000 -20.0 -4.0 260 45 23 7.6 4.2 | -20.2 -4.4 265 57 29 4.9 2.7 19500 -18.8 -1.8 260 44 22 7.6 4.2 | -19.5 -3.1 265 55 28 4.9 2.7 19000 -17.7 0.1 260 42 22 7.6 4.2 | -18.7 -1.7 265 53 27 5.0 2.7 18500 -16.6 2.1 265 41 21 7.1 3.9 | -17.6 0.3 260 50 26 5.5 3.0 18000 -15.6 3.9 265 41 21 6.6 3.6 | -16.8 1.8 260 48 25 5.6 3.1 17500 -14.6 5.7 265 41 21 6.7 3.7 | -16.0 3.2 260 46 24 5.8 3.2 17000 -13.8 7.2 265 41 21 4.9 2.7 | -15.1 4.8 260 43 22 6.0 3.3 16500 -13.1 8.4 265 40 21 5.1 2.8 | -14.2 6.4 255 40 21 5.9 3.2 16000 -12.3 9.9 265 39 20 4.8 2.6 | -13.2 8.2 255 37 19 7.7 4.2 15500 -11.3 11.7 265 35 18 4.6 2.5 | -12.1 10.2 255 33 17 7.5 4.1 15000 -10.6 12.9 265 33 17 5.8 3.2 | -10.9 12.4 250 30 16 8.5 4.7 14500 -9.7 14.5 265 30 15 5.8 3.2 | -9.6 14.7 250 28 14 8.6 4.7 14000 -8.8 16.2 260 27 14 6.8 3.7 | -8.3 17.1 245 25 13 8.5 4.7 13500 -7.7 18.1 260 24 12 7.1 3.9 | -7.1 19.2 245 23 12 8.5 4.6 13000 -6.7 19.9 260 21 11 7.1 3.9 | -5.8 21.6 245 22 11 8.3 4.6 12500 -5.6 21.9 255 19 10 7.1 3.9 | -4.6 23.7 245 20 10 8.2 4.5 12000 -4.6 23.7 250 16 8 7.3 4.0 | -3.4 25.9 245 19 10 8.0 4.4 11500 -3.5 25.7 240 14 7 7.5 4.1 | -2.2 28.0 240 16 8 7.7 4.3 11000 -2.3 27.9 235 12 6 6.9 3.8 | -1.0 30.2 235 14 7 7.1 3.9 10500 -1.3 29.7 225 11 6 5.6 3.1 | -0.1 31.8 230 11 6 5.4 3.0 10250 -0.9 30.4 220 10 5 10.3 5.7 | 0.4 32.7 225 10 5 9.5 5.2 10000 0.1 32.2 210 9 5 11.4 6.3 | 1.2 34.2 215 8 4 10.3 5.6 9750 0.7 33.3 205 9 5 7.3 4.0 | 1.8 35.2 210 8 4 6.7 3.7 9500 1.3 34.3 195 8 4 8.8 4.8 | 2.4 36.3 200 7 3 7.9 4.3 9250 2.0 35.6 190 8 4 6.8 3.7 | 2.9 37.2 190 6 3 6.7 3.7 9000 2.4 36.3 185 8 4 6.4 3.5 | 3.4 38.1 175 6 3 6.7 3.7 8750 3.0 37.4 180 7 4 8.7 4.8 | 4.0 39.2 165 6 3 8.6 4.7 8500 3.7 38.7 175 7 4 9.6 5.3 | 4.6 40.3 160 6 3 9.3 5.1 8250 4.4 39.9 170 6 3 8.0 4.4 | 5.3 41.5 155 7 3 8.5 4.6 8000 4.9 40.8 165 6 3 6.9 3.8 | 5.9 42.6 150 7 3 7.6 4.1 7750 5.5 41.9 160 6 3 9.4 5.2 | 6.5 43.7 145 7 4 8.4 4.6 7500 6.3 43.3 160 6 3 10.8 5.9 | 7.2 45.0 145 7 4 9.4 5.2 7250 7.0 44.6 155 6 3 8.6 4.7 | 7.8 46.0 145 8 4 8.1 4.4 7000 7.6 45.7 155 5 3 6.8 3.7 | 8.4 47.1 140 7 4 6.8 3.7 6750 8.2 46.8 155 5 3 10.9 6.0 | 9.0 48.2 135 7 4 9.1 5.0 6500 9.1 48.4 150 5 3 12.3 6.8 | 9.7 49.5 135 7 4 10.1 5.5 6250 9.9 49.8 150 5 3 9.7 5.3 | 10.4 50.7 130 7 3 8.5 4.7 6000 10.6 51.1 150 5 2 9.1 5.0 | 11.0 51.8 125 6 3 8.4 4.6 5750 11.3 52.3 150 4 2 11.0 6.0 | 11.7 53.1 115 6 3 7.8 4.3 5500 12.4 54.3 145 4 2 17.5 9.6 | 12.0 53.6 105 5 3 -1.8 -1.0 ________________________________________________________________________________ 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