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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000 UXUS97 KBOU 241311 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 0710 MDT Wednesday, April 24, 2024 This forecast is for Wednesday, April 24, 2024: If the trigger temperature of 66.4 F/19.1 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1205 ft/min (6.1 m/s) Maximum height of thermals.................. 18586 ft MSL (13270 ft AGL) Forecast maximum temperature................... 78.0 F/26.0 C Time of trigger temperature.................... 1200 MDT Time of overdevelopment........................ 1800 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 11930 ft MSL (6615 ft AGL) Thermal soaring outlook for Thursday 04/25..... Poor Wave Soaring Index............................. Fair Wave Soaring Index trend (to 1800 MDT)......... Becoming poor Height of stable layer (12-18K ft MSL)......... None Weak PVA/NVA (through 1800 MDT)................ Neither Potential height of wave....................... 17882 ft MSL (12566 ft AGL) Wave soaring outlook for Thursday 04/25........ Poor Remarks... 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.................. 12850 ft MSL (7534 ft AGL) Convective condensation level... 15690 ft MSL (10374 ft AGL) Lifted condensation level....... 16664 ft MSL (11349 ft AGL) Lifted index.................... -1.4 K index......................... +17.8 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 -57.6 -71.7 275 61 31 1.4 0.8 M M M M M 45000 -55.9 -68.6 270 64 33 -1.8 -1.0 M M M M M 40000 -58.5 -73.3 270 73 38 -1.6 -0.9 M M M M M 38000 -56.2 -69.2 265 72 37 6.2 3.4 M M M M M 36000 -52.4 -62.3 265 68 35 6.2 3.4 M M M M M 34000 -48.1 -54.6 265 62 32 6.7 3.7 M M M M M 32000 -44.1 -47.4 265 55 28 6.7 3.7 M M M M M 30000 -39.8 -39.6 265 48 25 7.7 4.2 35.9 96.7 7.8 M M 29000 -37.5 -35.5 265 45 23 7.7 4.2 35.1 95.1 7.3 M M 28000 -35.2 -31.4 265 42 22 7.7 4.2 34.3 93.8 6.8 M M 27000 -32.9 -27.2 265 41 21 7.8 4.3 33.6 92.5 6.3 M M 26000 -30.5 -22.9 265 40 21 7.8 4.3 32.8 91.0 5.7 M M 25000 -28.2 -18.8 265 40 21 7.8 4.3 32.1 89.7 5.2 M M 24000 -25.9 -14.6 265 40 20 7.1 3.9 31.4 88.5 4.7 M M 23000 -23.8 -10.8 265 38 19 7.2 3.9 30.3 86.6 3.9 M M 22000 -21.6 -6.9 265 36 18 7.2 3.9 29.4 85.0 3.2 M M 21000 -19.5 -3.1 265 34 17 6.5 3.6 28.5 83.2 2.4 M M 20000 -17.6 0.3 265 31 16 6.6 3.6 27.3 81.1 1.4 M M 19500 -16.6 2.1 265 30 16 6.6 3.6 26.8 80.2 0.9 M M 19000 -15.6 3.9 270 29 15 6.5 3.6 26.2 79.2 0.4 M M 18500 -14.6 5.7 270 29 15 7.6 4.2 25.8 78.4 0.0 M M 18000 -12.9 8.8 270 30 16 7.6 4.2 25.2 77.4 -0.5 1136 5.8 17500 -11.8 10.8 275 30 16 7.6 4.1 24.9 76.8 -0.9 1088 5.5 17000 -10.7 12.7 275 30 15 7.6 4.2 24.5 76.1 -1.2 1040 5.3 16500 -9.6 14.7 275 29 15 8.2 4.5 24.2 75.5 -1.6 992 5.0 16000 -8.3 17.1 280 28 15 8.6 4.7 24.0 75.1 -1.8 939 4.8 15500 -7.1 19.2 280 28 14 8.8 4.8 23.8 74.8 -2.0 886 4.5 15000 -5.7 21.7 280 27 14 9.2 5.0 23.6 74.6 -2.1 831 4.2 14500 -4.4 24.1 280 26 14 9.2 5.0 23.6 74.4 -2.2 775 3.9 14000 -3.0 26.6 280 25 13 9.2 5.1 23.5 74.2 -2.3 720 3.7 13500 -1.6 29.1 280 24 12 9.3 5.1 23.4 74.1 -2.4 663 3.4 13000 -0.3 31.5 280 23 12 8.7 4.8 23.3 73.9 -2.6 608 3.1 12500 1.0 33.8 280 21 11 8.7 4.8 23.1 73.5 -2.8 555 2.8 12000 2.3 36.1 285 19 10 7.9 4.3 22.9 73.2 -3.0 503 2.6 11500 3.4 38.1 285 17 9 7.9 4.4 22.6 72.6 -3.3 453 2.3 11000 4.5 40.1 285 16 8 6.5 3.6 22.2 71.9 -3.7 406 2.1 10500 5.4 41.7 280 14 7 6.9 3.8 21.6 70.9 -4.3 363 1.8 10250 5.9 42.6 280 13 7 4.0 2.2 21.4 70.4 -4.5 342 1.7 10000 6.1 43.0 280 13 6 3.3 1.8 20.8 69.4 -5.1 329 1.7 9750 6.4 43.5 275 12 6 5.4 3.0 20.4 68.7 -5.5 311 1.6 9500 6.8 44.2 265 11 6 5.2 2.9 20.0 68.1 -5.9 293 1.5 9250 7.1 44.8 260 11 6 3.8 2.1 19.7 67.4 -6.3 275 1.4 9000 7.3 45.1 250 11 6 1.9 1.1 19.1 66.4 -6.8 263 1.3 8750 7.5 45.5 240 11 6 2.3 1.3 18.5 65.3 -7.4 251 1.3 8500 7.6 45.7 230 12 6 2.7 1.5 17.9 64.3 -8.0 238 1.2 8250 7.8 46.0 220 13 7 1.3 0.7 17.4 63.3 -8.6 226 1.1 8000 7.8 46.0 220 14 7 0.2 0.1 16.6 62.0 -9.3 218 1.1 7750 7.9 46.2 215 15 8 1.2 0.6 15.9 60.7 -10.0 209 1.1 7500 8.0 46.4 205 16 8 1.5 0.8 15.3 59.5 -10.7 199 1.0 7250 8.1 46.6 205 17 9 1.5 0.8 14.7 58.4 -11.4 188 1.0 7000 8.2 46.8 200 18 9 1.5 0.8 14.0 57.3 -12.0 177 0.9 6750 8.3 46.9 200 19 10 1.9 1.0 13.4 56.2 -12.6 166 0.8 6500 8.4 47.1 195 18 9 0.7 0.4 12.8 55.1 -13.3 155 0.8 6250 8.4 47.1 195 17 9 -0.9 -0.5 12.0 53.7 -14.1 149 0.8 6000 8.3 46.9 195 16 8 0.3 0.2 11.3 52.3 -14.9 143 0.7 5750 8.3 46.9 195 15 8 -3.1 -1.7 10.5 50.9 -15.7 137 0.7 5500 7.7 45.9 190 10 5 -13.0 -7.1 9.2 48.5 -17.1 148 0.8 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 04/24/2024 at 0900 MDT | 04/24/2024 at 1200 MDT | CAPE... 0.0 LI... +0.4 | CAPE... +96.7 LI... -1.1 CINH... -0.0 K Index... +17.9 | CINH... -57.8 K Index... +18.6 | 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 -56.6 -69.9 275 59 30 1.3 0.7 | -56.2 -69.2 275 58 30 1.9 1.0 45000 -55.0 -67.0 270 66 34 -2.6 -1.4 | -53.8 -64.8 265 66 34 -3.3 -1.8 40000 -58.6 -73.5 260 71 37 -2.3 -1.3 | -58.5 -73.3 265 73 37 -2.7 -1.5 38000 -56.8 -70.2 255 70 36 5.6 3.1 | -56.5 -69.7 265 72 37 5.2 2.9 36000 -53.0 -63.4 255 67 35 5.6 3.1 | -53.4 -64.1 265 70 36 5.2 2.9 34000 -49.2 -56.6 255 62 32 7.3 4.0 | -49.7 -57.5 265 67 34 7.5 4.1 32000 -44.8 -48.6 260 55 28 7.3 4.0 | -45.2 -49.4 265 62 32 7.5 4.1 30000 -40.3 -40.5 260 48 25 7.8 4.3 | -40.8 -41.4 260 55 28 7.6 4.2 29000 -37.9 -36.2 260 45 23 7.8 4.3 | -38.5 -37.3 260 50 26 7.6 4.2 28000 -35.6 -32.1 260 42 21 7.8 4.3 | -35.7 -32.3 255 44 22 7.6 4.2 27000 -33.3 -27.9 260 40 20 7.5 4.1 | -33.4 -28.1 255 41 21 7.7 4.2 26000 -31.0 -23.8 260 39 20 7.5 4.1 | -31.1 -24.0 260 42 22 7.7 4.2 25000 -28.8 -19.8 260 39 20 7.6 4.1 | -28.8 -19.8 260 43 22 7.7 4.2 24000 -26.5 -15.7 260 39 20 7.0 3.8 | -26.6 -15.9 260 43 22 6.8 3.7 23000 -24.4 -11.9 260 36 19 7.0 3.9 | -24.5 -12.1 260 40 20 6.9 3.8 22000 -22.3 -8.1 265 34 18 7.0 3.9 | -22.4 -8.3 265 37 19 6.9 3.8 21000 -20.2 -4.4 265 32 17 6.8 3.7 | -20.4 -4.7 265 33 17 6.8 3.7 20000 -18.2 -0.8 265 30 15 6.8 3.7 | -18.4 -1.1 265 29 15 6.9 3.8 19500 -17.2 1.0 265 29 15 6.8 3.8 | -17.4 0.7 265 27 14 6.9 3.8 19000 -16.2 2.8 270 28 14 6.8 3.7 | -16.4 2.5 265 25 13 7.0 3.8 18500 -14.6 5.7 270 27 14 7.7 4.3 | -15.3 4.5 265 23 12 8.5 4.7 18000 -13.5 7.7 275 26 13 7.8 4.3 | -14.0 6.8 265 22 11 8.4 4.6 17500 -12.3 9.9 275 25 13 8.3 4.6 | -12.8 9.0 265 21 11 8.6 4.7 17000 -11.1 12.0 280 24 13 8.3 4.5 | -11.5 11.3 270 20 10 8.6 4.7 16500 -9.8 14.4 280 24 12 8.6 4.7 | -10.3 13.5 270 19 10 8.7 4.8 16000 -8.5 16.7 285 24 12 8.8 4.8 | -8.9 16.0 270 18 9 9.0 4.9 15500 -7.2 19.0 285 24 12 8.9 4.9 | -7.6 18.3 275 18 9 9.0 4.9 15000 -5.9 21.4 285 24 12 9.3 5.1 | -5.6 21.9 275 16 8 8.9 4.9 14500 -4.5 23.9 285 23 12 9.3 5.1 | -4.3 24.3 280 16 8 8.9 4.9 14000 -3.1 26.4 285 22 11 9.2 5.1 | -3.0 26.6 280 15 8 9.3 5.1 13500 -1.7 28.9 285 21 11 9.2 5.1 | -1.6 29.1 280 14 7 9.3 5.1 13000 -0.3 31.5 285 20 10 9.5 5.2 | -0.2 31.6 280 13 7 9.2 5.1 12500 1.1 34.0 285 19 10 9.5 5.2 | 1.2 34.2 280 12 6 9.3 5.1 12000 2.5 36.5 285 18 9 9.2 5.0 | 2.5 36.5 280 12 6 9.2 5.0 11500 3.9 39.0 285 17 9 9.2 5.1 | 3.9 39.0 275 11 6 9.2 5.0 11000 5.2 41.4 285 16 8 8.8 4.8 | 5.3 41.5 275 10 5 9.3 5.1 10500 6.5 43.7 285 14 7 9.8 5.4 | 6.6 43.9 275 9 5 10.3 5.6 10250 7.2 45.0 285 14 7 4.7 2.6 | 7.3 45.1 275 9 4 5.3 2.9 10000 7.4 45.3 285 13 7 5.0 2.7 | 7.6 45.7 275 9 4 6.5 3.6 9750 8.0 46.4 285 12 6 9.9 5.4 | 8.4 47.1 270 8 4 12.0 6.6 9500 8.7 47.7 280 11 6 9.5 5.2 | 9.2 48.6 270 7 4 11.7 6.4 9250 9.4 48.9 280 10 5 6.2 3.4 | 10.0 50.0 265 7 4 7.4 4.1 9000 9.6 49.3 275 9 5 3.9 2.2 | 10.4 50.7 265 6 3 6.5 3.6 8750 10.0 50.0 270 8 4 6.3 3.4 | 11.1 52.0 265 6 3 10.6 5.8 8500 10.5 50.9 265 8 4 6.2 3.4 | 11.9 53.4 260 5 3 9.7 5.3 8250 10.9 51.6 255 7 4 4.1 2.2 | 12.5 54.5 255 5 2 6.1 3.4 8000 11.1 52.0 250 7 4 2.0 1.1 | 12.8 55.0 250 4 2 4.8 2.6 7750 11.2 52.2 245 7 4 2.1 1.2 | 13.3 55.9 245 3 2 8.3 4.6 7500 11.3 52.3 235 8 4 1.0 0.6 | 13.9 57.0 240 2 1 7.4 4.0 7250 11.3 52.3 230 8 4 -0.9 -0.5 | 14.3 57.7 240 2 1 4.1 2.2 7000 11.2 52.2 230 8 4 -1.5 -0.8 | 14.5 58.1 250 1 0 3.5 1.9 6750 11.1 52.0 225 8 4 -2.1 -1.2 | 14.9 58.8 000 0 0 9.2 5.1 6500 10.9 51.6 220 9 4 -0.7 -0.4 | 15.7 60.3 355 1 0 10.9 6.0 6250 10.9 51.6 215 8 4 1.7 0.9 | 16.4 61.5 360 1 0 8.9 4.9 6000 11.0 51.8 210 8 4 -0.0 -0.0 | 17.1 62.8 005 1 1 8.5 4.7 5750 11.0 51.8 205 8 4 4.8 2.6 | 17.8 64.0 005 2 1 13.0 7.1 5500 11.8 53.2 200 6 3 17.0 9.3 | 19.2 66.6 005 1 1 25.4 14.0 04/24/2024 at 1500 MDT | 04/24/2024 at 1800 MDT | CAPE... +196.6 LI... -1.2 | CAPE... +227.5 LI... -0.8 CINH... -15.5 K Index... +23.5 | CINH... -31.6 K Index... +23.1 | 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 -55.9 -68.6 270 57 29 2.1 1.1 | -55.8 -68.4 270 56 29 1.7 0.9 45000 -53.4 -64.1 265 66 34 -3.8 -2.1 | -53.8 -64.8 270 68 35 -3.7 -2.1 40000 -58.7 -73.7 265 77 40 -3.1 -1.7 | -59.0 -74.2 265 79 41 -3.1 -1.7 38000 -56.8 -70.2 265 78 40 5.4 3.0 | -56.8 -70.2 265 80 41 6.0 3.3 36000 -53.5 -64.3 265 78 40 5.4 3.0 | -53.2 -63.8 265 79 41 6.0 3.3 34000 -49.7 -57.5 265 77 39 7.8 4.3 | -49.3 -56.7 265 76 39 7.4 4.1 32000 -45.0 -49.0 265 73 37 7.8 4.3 | -44.9 -48.8 265 70 36 7.4 4.1 30000 -40.4 -40.7 265 67 34 7.7 4.2 | -39.8 -39.6 265 63 32 7.9 4.3 29000 -37.5 -35.5 265 61 31 7.7 4.2 | -37.4 -35.3 265 59 31 7.9 4.3 28000 -35.2 -31.4 265 56 29 7.7 4.2 | -35.0 -31.0 265 56 29 7.8 4.3 27000 -33.0 -27.4 265 52 27 7.0 3.9 | -32.8 -27.0 265 53 27 7.2 4.0 26000 -30.9 -23.6 265 49 25 7.1 3.9 | -30.6 -23.1 265 50 26 7.2 4.0 25000 -28.8 -19.8 265 46 24 7.1 3.9 | -28.5 -19.3 265 46 24 7.2 4.0 24000 -26.7 -16.1 260 43 22 7.3 4.0 | -26.3 -15.3 260 43 22 7.4 4.0 23000 -24.6 -12.3 260 40 21 7.3 4.0 | -24.2 -11.6 260 39 20 7.4 4.1 22000 -22.4 -8.3 260 36 19 7.4 4.0 | -22.0 -7.6 260 35 18 7.5 4.1 21000 -20.2 -4.4 255 33 17 8.1 4.5 | -19.6 -3.3 255 32 16 8.7 4.8 20000 -17.8 -0.0 255 29 15 8.1 4.5 | -17.1 1.2 250 28 14 8.7 4.8 19500 -16.6 2.1 250 27 14 8.2 4.5 | -15.8 3.6 250 26 14 8.7 4.8 19000 -15.4 4.3 250 25 13 8.2 4.5 | -14.5 5.9 250 25 13 8.8 4.8 18500 -14.2 6.4 250 24 12 8.3 4.6 | -13.3 8.1 245 23 12 8.1 4.4 18000 -13.0 8.6 250 23 12 8.3 4.6 | -12.1 10.2 245 23 12 8.1 4.5 17500 -11.8 10.8 250 22 11 7.9 4.3 | -10.9 12.4 245 22 11 8.0 4.4 17000 -10.6 12.9 245 20 10 7.7 4.2 | -9.7 14.5 245 21 11 7.9 4.3 16500 -9.5 14.9 245 19 10 7.8 4.3 | -8.6 16.5 245 20 10 7.9 4.4 16000 -8.3 17.1 245 18 9 8.4 4.6 | -7.4 18.7 240 19 10 8.4 4.6 15500 -6.4 20.5 240 15 8 8.7 4.8 | -5.5 22.1 240 17 9 8.5 4.6 15000 -5.1 22.8 240 14 7 9.3 5.1 | -4.2 24.4 240 15 8 8.7 4.8 14500 -3.7 25.3 235 13 7 9.3 5.1 | -3.0 26.6 240 13 7 8.7 4.8 14000 -2.3 27.9 235 12 6 9.3 5.1 | -1.6 29.1 235 12 6 9.2 5.0 13500 -1.0 30.2 230 11 6 9.3 5.1 | -0.3 31.5 235 10 5 9.1 5.0 13000 0.4 32.7 230 10 5 9.4 5.1 | 1.1 34.0 230 9 5 9.5 5.2 12500 1.8 35.2 225 9 5 9.4 5.1 | 2.5 36.5 225 8 4 9.5 5.2 12000 3.2 37.8 225 8 4 9.4 5.1 | 3.9 39.0 220 7 3 9.6 5.2 11500 4.6 40.3 220 7 3 9.5 5.2 | 5.3 41.5 210 6 3 9.7 5.3 11000 5.9 42.6 215 6 3 7.6 4.2 | 6.7 44.1 205 5 3 8.0 4.4 10500 7.1 44.8 210 5 3 6.2 3.4 | 7.8 46.0 200 5 3 7.0 3.8 10250 7.6 45.7 210 5 2 12.9 7.1 | 8.5 47.3 200 5 2 12.5 6.9 10000 8.8 47.8 210 4 2 14.1 7.7 | 9.6 49.3 190 5 2 13.3 7.3 9750 9.5 49.1 205 3 2 8.0 4.4 | 10.3 50.5 185 5 2 8.5 4.7 9500 10.2 50.4 200 3 2 10.3 5.7 | 11.0 51.8 180 4 2 10.3 5.6 9250 10.9 51.6 195 3 1 7.3 4.0 | 11.7 53.1 175 4 2 8.0 4.4 9000 11.4 52.5 185 2 1 8.1 4.4 | 12.3 54.1 180 3 2 8.4 4.6 8750 12.2 54.0 180 2 1 11.0 6.0 | 13.0 55.4 170 3 2 10.4 5.7 8500 13.0 55.4 175 1 1 10.9 6.0 | 13.8 56.8 165 3 2 10.4 5.7 8250 13.7 56.7 165 1 1 8.5 4.7 | 14.5 58.1 160 3 2 8.5 4.7 8000 14.3 57.7 125 1 0 8.0 4.4 | 15.1 59.2 155 2 1 7.9 4.3 7750 15.0 59.0 110 1 0 11.0 6.0 | 15.7 60.3 150 2 1 9.8 5.4 7500 15.8 60.4 095 1 0 10.7 5.8 | 16.5 61.7 140 2 1 10.0 5.5 7250 16.5 61.7 085 1 0 8.0 4.4 | 17.2 63.0 135 2 1 7.8 4.3 7000 17.0 62.6 070 1 1 7.2 3.9 | 17.7 63.9 125 2 1 6.8 3.7 6750 17.7 63.9 065 1 1 11.9 6.5 | 18.3 64.9 115 1 1 10.1 5.5 6500 18.7 65.7 060 1 1 12.3 6.8 | 19.1 66.4 115 1 1 10.7 5.9 6250 19.5 67.1 060 1 1 9.3 5.1 | 19.8 67.6 105 1 1 8.9 4.9 6000 20.1 68.2 055 2 1 8.9 4.9 | 20.4 68.7 090 1 1 8.4 4.6 5750 20.8 69.4 050 2 1 10.5 5.8 | 21.1 70.0 075 1 1 9.5 5.2 5500 21.8 71.2 045 1 1 16.5 9.0 | 21.8 71.2 070 1 1 11.9 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. 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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