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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000 UXUS97 KBOU 240046 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1846 MDT Tuesday, April 23, 2024 This forecast is for Wednesday, April 24, 2024: If the trigger temperature of 66.5 F/19.2 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1090 ft/min (5.5 m/s) Maximum height of thermals.................. 17458 ft MSL (12178 ft AGL) Forecast maximum temperature................... 77.0 F/25.5 C Time of trigger temperature.................... 1045 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................. 10770 ft MSL (5490 ft AGL) Thermal soaring outlook for Thursday 04/25..... Good Wave Soaring Index............................. Fair 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....................... 14900 ft MSL (9620 ft AGL) Wave soaring outlook for Thursday 04/25........ Poor Remarks... Warmer wedensday, an isolated shower or two possible in the afternoon Sunrise/Sunset.................... 06:07:51 / 19:47:06 MDT Total possible sunshine........... 13 hr 39 min 16 sec (819 min 16 sec) Altitude of sun at 12:57:29 MDT... 63.44 degrees Upper air data from numerical model forecast valid on 04/24/2024 at 0600 MDT Freezing level.................. 12969 ft MSL (7689 ft AGL) Convective condensation level... 14388 ft MSL (9108 ft AGL) Lifted condensation level....... 15114 ft MSL (9835 ft AGL) Lifted index.................... -2.6 K index......................... +20.5 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 -57.1 -70.8 280 61 31 1.0 0.6 M M M M M 45000 -56.0 -68.8 270 67 34 -2.2 -1.2 M M M M M 40000 -59.2 -74.6 270 71 37 -1.9 -1.0 M M M M M 38000 -56.7 -70.1 270 70 36 6.5 3.6 M M M M M 36000 -52.7 -62.9 265 69 35 6.5 3.6 M M M M M 34000 -48.2 -54.8 265 64 33 6.9 3.8 M M M M M 32000 -44.1 -47.4 265 56 29 6.9 3.8 M M M M M 30000 -39.6 -39.3 265 49 25 8.0 4.4 36.2 97.1 8.4 M M 29000 -37.2 -35.0 265 46 24 8.0 4.4 35.4 95.8 8.0 M M 28000 -34.8 -30.6 265 43 22 8.0 4.4 34.8 94.7 7.6 M M 27000 -32.5 -26.5 265 41 21 7.6 4.2 34.1 93.4 7.1 M M 26000 -30.2 -22.4 265 40 20 7.6 4.2 33.2 91.8 6.5 M M 25000 -27.9 -18.2 265 38 20 7.7 4.2 32.5 90.5 6.0 M M 24000 -25.6 -14.1 265 36 19 6.9 3.8 31.7 89.1 5.4 M M 23000 -23.5 -10.3 265 34 18 7.0 3.9 30.6 87.1 4.6 M M 22000 -21.4 -6.5 265 33 17 7.0 3.9 29.7 85.4 3.8 M M 21000 -19.3 -2.7 270 31 16 7.1 3.9 28.7 83.7 3.0 M M 20000 -17.2 1.0 270 30 15 7.1 3.9 27.7 81.9 2.2 M M 19500 -16.2 2.8 270 29 15 7.1 3.9 27.3 81.1 1.8 M M 19000 -15.1 4.8 270 29 15 7.2 3.9 26.9 80.4 1.4 M M 18500 -14.1 6.6 270 28 15 7.0 3.8 26.4 79.5 1.0 M M 18000 -13.1 8.4 270 27 14 7.0 3.9 25.9 78.7 0.6 M M 17500 -12.1 10.2 270 27 14 7.2 4.0 25.5 77.9 0.1 M M 17000 -11.0 12.2 270 26 13 7.4 4.1 25.1 77.1 -0.3 1058 5.4 16500 -9.4 15.1 270 24 12 8.5 4.6 24.5 76.1 -0.8 987 5.0 16000 -8.1 17.4 275 24 12 8.9 4.9 24.4 75.8 -1.0 932 4.7 15500 -6.7 19.9 275 24 12 9.0 4.9 24.2 75.6 -1.1 878 4.5 15000 -5.4 22.3 275 24 13 9.2 5.1 24.1 75.4 -1.2 822 4.2 14500 -4.0 24.8 275 25 13 9.2 5.1 24.0 75.3 -1.3 765 3.9 14000 -2.6 27.3 275 25 13 9.2 5.1 24.0 75.1 -1.4 709 3.6 13500 -1.2 29.8 280 24 12 9.3 5.1 23.9 75.0 -1.5 653 3.3 13000 0.1 32.2 280 22 12 8.8 4.8 23.7 74.7 -1.6 598 3.0 12500 1.4 34.5 280 21 11 8.9 4.9 23.6 74.5 -1.8 544 2.8 12000 2.7 36.9 280 19 10 7.8 4.3 23.4 74.1 -2.0 491 2.5 11500 3.8 38.8 280 17 9 7.9 4.3 23.1 73.5 -2.3 442 2.2 11000 4.9 40.8 280 14 7 6.2 3.4 22.6 72.8 -2.8 396 2.0 10500 5.8 42.4 275 12 6 6.8 3.8 22.1 71.7 -3.4 355 1.8 10250 6.2 43.2 275 11 6 3.2 1.7 21.8 71.2 -3.7 334 1.7 10000 6.3 43.3 275 11 6 2.2 1.2 21.1 70.0 -4.3 324 1.6 9750 6.6 43.9 270 10 5 5.1 2.8 20.7 69.2 -4.8 308 1.6 9500 6.9 44.4 265 10 5 4.8 2.6 20.3 68.5 -5.2 291 1.5 9250 7.2 45.0 255 9 5 3.4 1.9 19.9 67.8 -5.7 275 1.4 9000 7.3 45.1 250 9 5 1.1 0.6 19.3 66.7 -6.3 264 1.3 8750 7.4 45.3 245 9 5 0.8 0.4 18.6 65.4 -7.0 255 1.3 8500 7.4 45.3 235 10 5 0.7 0.4 17.9 64.2 -7.7 247 1.3 8250 7.4 45.3 225 10 5 0.3 0.2 17.2 62.9 -8.5 239 1.2 8000 7.4 45.3 225 11 6 0.0 0.0 16.4 61.6 -9.2 232 1.2 7750 7.4 45.3 220 11 6 -0.0 -0.0 15.7 60.2 -10.0 224 1.1 7500 7.4 45.3 215 12 6 0.2 0.1 14.9 58.9 -10.7 217 1.1 7250 7.4 45.3 210 12 6 1.0 0.5 14.2 57.6 -11.5 209 1.1 7000 7.5 45.5 205 13 6 0.7 0.4 13.5 56.4 -12.1 199 1.0 6750 7.6 45.7 205 13 7 2.7 1.5 12.9 55.2 -12.8 190 1.0 6500 7.8 46.0 200 13 7 0.9 0.5 12.4 54.3 -13.4 176 0.9 6250 7.6 45.7 200 11 6 -2.5 -1.4 11.5 52.7 -14.3 173 0.9 6000 7.5 45.5 195 10 5 -1.3 -0.7 10.6 51.1 -15.2 170 0.9 5750 7.3 45.1 195 9 5 -2.6 -1.4 9.8 49.6 -16.1 166 0.8 5500 7.0 44.6 190 6 3 -6.6 -3.6 8.7 47.6 -17.3 170 0.9 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 04/24/2024 at 0900 MDT | 04/24/2024 at 1200 MDT | CAPE... 0.0 LI... +0.7 | CAPE... +170.8 LI... -1.5 CINH... -0.1 K Index... +17.9 | CINH... -84.9 K Index... +18.5 | 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 -56.9 -70.4 275 59 31 0.9 0.5 | -56.7 -70.1 275 57 30 1.3 0.7 45000 -55.9 -68.6 270 66 34 -2.0 -1.1 | -55.1 -67.2 265 66 34 -2.6 -1.4 40000 -58.8 -73.8 260 69 35 -1.8 -1.0 | -58.8 -73.8 265 71 37 -2.4 -1.3 38000 -56.8 -70.2 260 68 35 5.7 3.1 | -56.6 -69.9 260 70 36 5.5 3.0 36000 -52.9 -63.2 255 67 34 5.7 3.1 | -53.3 -63.9 260 67 34 5.5 3.0 34000 -49.0 -56.2 255 62 32 7.5 4.1 | -49.5 -57.1 260 63 33 7.5 4.1 32000 -44.5 -48.1 260 55 28 7.5 4.1 | -45.1 -49.2 260 58 30 7.5 4.1 30000 -39.9 -39.8 260 48 25 7.7 4.2 | -40.6 -41.1 260 52 27 7.7 4.2 29000 -37.6 -35.7 260 45 23 7.7 4.2 | -37.7 -35.9 260 47 24 7.7 4.2 28000 -35.3 -31.5 260 41 21 7.7 4.2 | -35.4 -31.7 260 44 22 7.8 4.3 27000 -33.0 -27.4 260 39 20 7.7 4.2 | -33.0 -27.4 260 41 21 7.8 4.3 26000 -30.7 -23.3 260 39 20 7.7 4.2 | -30.7 -23.3 260 41 21 7.8 4.3 25000 -28.4 -19.1 260 39 20 7.7 4.2 | -28.4 -19.1 260 41 21 7.8 4.3 24000 -26.1 -15.0 265 39 20 7.5 4.1 | -26.1 -15.0 265 40 21 7.8 4.3 23000 -23.8 -10.8 265 37 19 7.5 4.1 | -23.7 -10.7 265 39 20 7.8 4.3 22000 -21.6 -6.9 265 36 19 7.5 4.1 | -21.4 -6.5 265 37 19 7.8 4.3 21000 -19.4 -2.9 265 34 18 6.4 3.5 | -19.3 -2.7 265 34 18 5.9 3.3 20000 -17.5 0.5 265 32 17 6.4 3.5 | -17.6 0.3 265 30 16 6.0 3.3 19500 -16.6 2.1 265 31 16 6.5 3.5 | -16.7 1.9 265 28 15 6.0 3.3 19000 -15.6 3.9 265 30 15 6.4 3.5 | -15.8 3.6 265 26 14 6.1 3.3 18500 -14.2 6.4 265 28 14 7.0 3.8 | -14.8 5.4 265 25 13 8.1 4.4 18000 -13.1 8.4 265 26 13 7.0 3.8 | -13.6 7.5 265 23 12 7.9 4.4 17500 -12.1 10.2 265 25 13 8.1 4.4 | -12.4 9.7 265 22 11 8.2 4.5 17000 -10.9 12.4 265 23 12 8.0 4.4 | -11.2 11.8 265 21 11 8.3 4.6 16500 -9.7 14.5 270 22 11 8.7 4.8 | -10.0 14.0 265 19 10 8.4 4.6 16000 -8.3 17.1 270 22 11 9.0 4.9 | -8.7 16.3 270 19 10 9.0 4.9 15500 -7.0 19.4 275 21 11 9.1 5.0 | -6.7 19.9 270 17 9 8.9 4.9 15000 -5.6 21.9 275 21 11 9.3 5.1 | -5.5 22.1 270 17 9 8.8 4.8 14500 -4.2 24.4 275 21 11 9.3 5.1 | -4.2 24.4 270 16 8 8.8 4.8 14000 -2.9 26.8 275 20 10 9.1 5.0 | -2.9 26.8 270 15 8 9.0 4.9 13500 -1.5 29.3 280 19 10 9.2 5.0 | -1.6 29.1 270 13 7 8.9 4.9 13000 -0.2 31.6 280 18 9 8.9 4.9 | -0.2 31.6 270 12 6 9.4 5.1 12500 1.1 34.0 280 17 9 8.9 4.9 | 1.2 34.2 270 11 6 9.4 5.1 12000 2.4 36.3 280 16 8 8.7 4.8 | 2.6 36.7 270 11 5 9.0 4.9 11500 3.7 38.7 280 15 8 8.8 4.9 | 3.9 39.0 265 9 5 9.0 5.0 11000 5.0 41.0 280 13 7 7.6 4.2 | 5.3 41.5 265 8 4 9.2 5.0 10500 6.1 43.0 275 11 6 8.4 4.6 | 6.6 43.9 265 7 4 10.1 5.6 10250 6.6 43.9 275 10 5 4.0 2.2 | 7.3 45.1 260 7 4 5.3 2.9 10000 6.8 44.2 275 10 5 4.4 2.4 | 7.5 45.5 260 6 3 6.1 3.4 9750 7.4 45.3 270 9 4 8.7 4.8 | 8.3 46.9 260 6 3 11.1 6.1 9500 8.0 46.4 270 8 4 8.5 4.7 | 9.1 48.4 255 6 3 10.9 6.0 9250 8.5 47.3 265 7 4 5.1 2.8 | 9.8 49.6 250 5 3 6.7 3.7 9000 8.7 47.7 265 6 3 2.6 1.4 | 10.1 50.2 245 4 2 5.7 3.1 8750 9.0 48.2 260 6 3 5.0 2.8 | 10.8 51.4 235 4 2 9.7 5.3 8500 9.4 48.9 255 6 3 5.0 2.7 | 11.5 52.7 225 4 2 8.7 4.8 8250 9.7 49.5 250 6 3 3.2 1.8 | 12.0 53.6 215 4 2 5.6 3.1 8000 9.8 49.6 245 6 3 1.4 0.8 | 12.3 54.1 205 4 2 4.0 2.2 7750 9.9 49.8 240 6 3 0.9 0.5 | 12.7 54.9 195 4 2 6.5 3.6 7500 9.8 49.6 235 6 3 -0.7 -0.4 | 13.1 55.6 190 4 2 6.0 3.3 7250 9.7 49.5 235 6 3 -2.7 -1.5 | 13.5 56.3 185 4 2 4.1 2.2 7000 9.4 48.9 235 6 3 -3.4 -1.9 | 13.7 56.7 180 3 2 3.8 2.1 6750 9.1 48.4 235 6 3 -3.4 -1.9 | 14.1 57.4 180 3 2 8.6 4.7 6500 8.9 48.0 225 6 3 -1.0 -0.5 | 14.8 58.6 175 3 1 10.3 5.7 6250 8.9 48.0 225 5 3 1.8 1.0 | 15.4 59.7 175 3 1 8.8 4.8 6000 9.0 48.2 220 5 3 -0.7 -0.4 | 16.1 61.0 175 2 1 8.3 4.5 5750 9.0 48.2 215 5 2 6.4 3.5 | 16.8 62.2 175 2 1 13.2 7.2 5500 10.0 50.0 210 4 2 22.0 12.1 | 18.2 64.8 175 2 1 25.9 14.2 04/24/2024 at 1500 MDT | 04/24/2024 at 1800 MDT | CAPE... +204.7 LI... -1.1 | CAPE... +432.7 LI... -1.7 CINH... -15.2 K Index... +25.2 | CINH... -26.0 K Index... +25.7 | 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 -56.5 -69.7 270 55 28 1.8 1.0 | -56.5 -69.7 270 54 28 1.0 0.6 45000 -54.4 -65.9 265 64 33 -3.2 -1.8 | -55.3 -67.5 270 63 32 -2.4 -1.3 40000 -59.0 -74.2 265 77 39 -3.0 -1.6 | -58.7 -73.7 265 74 38 -2.3 -1.3 38000 -56.7 -70.1 265 77 40 5.8 3.2 | -56.2 -69.2 265 74 38 5.9 3.2 36000 -53.2 -63.8 265 77 40 5.8 3.2 | -52.7 -62.9 265 73 38 5.9 3.2 34000 -49.3 -56.7 265 75 38 7.8 4.3 | -48.7 -55.7 265 71 36 7.6 4.2 32000 -44.6 -48.3 265 70 36 7.8 4.3 | -44.2 -47.6 265 66 34 7.6 4.2 30000 -40.0 -40.0 265 63 33 7.7 4.2 | -39.6 -39.3 265 61 32 8.0 4.4 29000 -37.7 -35.9 265 59 30 7.7 4.2 | -37.2 -35.0 270 58 30 8.0 4.4 28000 -34.8 -30.6 265 53 27 7.6 4.2 | -34.2 -29.6 270 54 28 8.0 4.4 27000 -32.6 -26.7 265 49 25 6.9 3.8 | -31.9 -25.4 270 51 26 7.1 3.9 26000 -30.6 -23.1 265 46 24 6.9 3.8 | -29.8 -21.6 265 48 25 7.1 3.9 25000 -28.5 -19.3 265 42 22 7.0 3.8 | -27.7 -17.9 265 45 23 7.1 3.9 24000 -26.4 -15.5 265 39 20 8.3 4.5 | -25.6 -14.1 265 41 21 7.3 4.0 23000 -23.9 -11.0 260 37 19 8.2 4.5 | -23.4 -10.1 265 38 20 7.4 4.0 22000 -21.5 -6.7 260 35 18 8.2 4.5 | -21.2 -6.2 260 36 18 7.5 4.1 21000 -19.1 -2.4 255 33 17 7.8 4.3 | -18.9 -2.0 260 32 17 8.5 4.7 20000 -16.8 1.8 255 32 16 7.9 4.3 | -16.4 2.5 255 29 15 8.6 4.7 19500 -15.7 3.7 255 31 16 7.9 4.3 | -15.2 4.6 255 28 14 8.6 4.7 19000 -14.5 5.9 255 30 15 7.9 4.3 | -13.9 7.0 250 26 13 8.6 4.7 18500 -13.4 7.9 255 28 14 7.6 4.2 | -12.7 9.1 250 25 13 8.0 4.4 18000 -12.3 9.9 250 25 13 7.7 4.2 | -11.5 11.3 250 24 12 8.1 4.4 17500 -11.2 11.8 250 23 12 7.6 4.2 | -10.4 13.3 250 23 12 7.3 4.0 17000 -10.1 13.8 250 22 11 7.6 4.2 | -9.4 15.1 250 22 11 6.9 3.8 16500 -9.0 15.8 250 20 10 7.6 4.2 | -8.4 16.9 250 21 11 7.0 3.9 16000 -7.8 18.0 250 19 10 7.6 4.2 | -7.2 19.0 250 19 10 7.8 4.3 15500 -6.7 19.9 250 17 9 7.5 4.1 | -6.1 21.0 250 18 9 7.7 4.2 15000 -5.5 22.1 245 15 8 9.0 5.0 | -4.9 23.2 250 16 8 8.9 4.9 14500 -4.1 24.6 245 13 7 8.9 4.9 | -3.5 25.7 250 14 7 8.9 4.9 14000 -2.8 27.0 240 12 6 9.2 5.0 | -2.2 28.0 250 13 6 8.8 4.8 13500 -1.4 29.5 235 10 5 9.3 5.1 | -0.3 31.5 250 10 5 8.8 4.8 13000 -0.0 32.0 235 9 5 9.2 5.0 | 1.1 34.0 245 9 5 8.8 4.8 12500 2.0 35.6 225 7 4 9.1 5.0 | 2.4 36.3 245 8 4 8.8 4.8 12000 3.4 38.1 215 7 4 9.1 5.0 | 3.7 38.7 240 6 3 9.1 5.0 11500 4.7 40.5 205 6 3 9.3 5.1 | 5.0 41.0 230 5 3 9.2 5.0 11000 6.0 42.8 200 6 3 7.2 4.0 | 6.3 43.3 220 4 2 7.6 4.2 10500 7.1 44.8 195 6 3 6.0 3.3 | 7.4 45.3 210 4 2 6.2 3.4 10250 7.6 45.7 190 6 3 12.8 7.0 | 8.0 46.4 205 4 2 12.6 6.9 10000 8.8 47.8 185 5 3 14.2 7.8 | 9.1 48.4 190 5 3 13.7 7.5 9750 9.5 49.1 180 5 3 8.0 4.4 | 9.8 49.6 185 5 3 7.7 4.2 9500 10.2 50.4 175 5 3 10.6 5.8 | 10.4 50.7 180 6 3 10.3 5.6 9250 10.9 51.6 170 5 2 6.3 3.4 | 11.1 52.0 175 7 3 6.1 3.4 9000 11.3 52.3 170 5 2 7.4 4.1 | 11.4 52.5 175 7 3 7.1 3.9 8750 12.1 53.8 165 4 2 12.0 6.6 | 12.2 54.0 170 7 4 11.3 6.2 8500 12.9 55.2 160 4 2 10.9 6.0 | 13.0 55.4 170 7 4 10.9 6.0 8250 13.7 56.7 160 4 2 7.5 4.1 | 13.7 56.7 165 8 4 8.4 4.6 8000 14.1 57.4 155 4 2 7.6 4.1 | 14.2 57.6 165 7 4 7.6 4.1 7750 14.9 58.8 155 4 2 12.1 6.6 | 15.0 59.0 165 7 4 10.6 5.8 7500 15.7 60.3 150 4 2 11.1 6.1 | 15.7 60.3 160 7 4 10.3 5.7 7250 16.5 61.7 145 4 2 8.2 4.5 | 16.4 61.5 155 7 4 8.2 4.5 7000 17.0 62.6 145 4 2 7.8 4.3 | 17.0 62.6 155 7 4 7.3 4.0 6750 17.8 64.0 140 4 2 12.4 6.8 | 17.6 63.7 155 7 4 10.6 5.8 6500 18.7 65.7 135 4 2 11.7 6.4 | 18.5 65.3 150 7 4 10.6 5.8 6250 19.4 66.9 135 4 2 8.4 4.6 | 19.1 66.4 150 7 3 8.2 4.5 6000 20.1 68.2 130 3 2 8.6 4.7 | 19.7 67.5 145 6 3 7.6 4.2 5750 20.8 69.4 130 3 2 12.2 6.7 | 20.3 68.5 145 6 3 10.3 5.7 5500 22.0 71.6 130 3 2 20.3 11.1 | 21.2 70.2 140 5 3 13.3 7.3 ________________________________________________________________________________ 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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