471 UXUS97 KBOU 240133 SRGBOU Soaring Forecast National Weather Service Denver/Boulder, Colorado 1832 MST Saturday, February 23, 2019 This forecast is for Sunday, February 24, 2019: If the trigger temperature of 41.7 F/5.4 C is reached...then Thermal Soaring Index....................... Fair Maximum rate of lift........................ 313 ft/min (1.6 m/s) Maximum height of thermals.................. 9780 ft MSL (4453 ft AGL) Forecast maximum temperature................... 43.0 F/6.6 C Time of trigger temperature.................... 1200 MST 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................. 8277 ft MSL (2951 ft AGL) Thermal soaring outlook for Monday 02/25....... Fair Wave Soaring Index............................. Poor Wave Soaring Index trend (to 1700 MST)......... No change Height of stable layer (12-18K ft MSL)......... None Weak PVA/NVA (through 1700 MST)................ Neither Potential height of wave....................... 52518 ft MSL (47191 ft AGL) Wave soaring outlook for Monday 02/25.......... Poor Remarks... Sunrise/Sunset.................... 06:39:46 / 17:45:35 MST Total possible sunshine........... 11 hr 5 min 48 sec (665 min 48 sec) Altitude of sun at 12:12:41 MST... 40.79 degrees Upper air data from numerical model forecast valid on 02/24/2019 at 0500 MST Freezing level.................. Entire airmass below 32 F / 0 C Convective condensation level... 18419 ft MSL (13092 ft AGL) Lifted condensation level....... 15394 ft MSL (10068 ft AGL) Lifted index.................... +8.9 K index......................... -24.4 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 -56.3 -69.3 260 37 19 -0.3 -0.2 M M M M M 45000 -56.8 -70.2 265 43 22 -0.3 -0.2 M M M M M 40000 -59.8 -75.6 275 45 23 -2.3 -1.3 M M M M M 38000 -61.1 -78.0 280 46 24 0.8 0.5 M M M M M 36000 -60.2 -76.4 275 46 24 1.5 0.8 M M M M M 34000 -59.3 -74.7 275 46 24 1.6 0.9 M M M M M 32000 -55.9 -68.6 280 45 23 6.9 3.8 M M M M M 30000 -51.3 -60.3 280 43 22 7.1 3.9 M M M M M 29000 -49.0 -56.2 280 42 22 7.8 4.3 23.8 74.8 13.3 M M 28000 -46.7 -52.1 280 42 22 7.8 4.3 22.9 73.3 12.9 M M 27000 -44.4 -47.9 280 41 21 7.7 4.3 22.3 72.1 12.5 M M 26000 -42.1 -43.8 280 41 21 7.6 4.2 21.5 70.7 12.1 M M 25000 -39.8 -39.6 280 40 20 7.6 4.2 20.6 69.1 11.5 M M 24000 -37.5 -35.5 280 39 20 7.6 4.2 19.9 67.8 11.1 M M 23000 -35.2 -31.4 280 37 19 7.3 4.0 19.1 66.4 10.5 M M 22000 -33.0 -27.4 285 36 18 7.3 4.0 18.1 64.6 9.9 M M 21000 -30.9 -23.6 285 34 18 7.3 4.0 17.3 63.2 9.3 M M 20000 -28.7 -19.7 285 32 16 7.0 3.8 16.3 61.4 8.6 M M 19500 -27.7 -17.9 285 31 16 7.0 3.8 15.8 60.5 8.2 M M 19000 -26.6 -15.9 285 29 15 7.0 3.8 15.4 59.6 7.9 M M 18500 -25.6 -14.1 285 28 15 7.0 3.9 14.9 58.8 7.5 M M 18000 -24.6 -12.3 285 27 14 6.7 3.7 14.5 58.0 7.2 M M 17500 -23.6 -10.5 290 26 14 6.7 3.7 13.9 57.0 6.8 M M 17000 -22.0 -7.6 290 25 13 7.2 4.0 13.2 55.7 6.2 M M 16500 -20.9 -5.6 285 23 12 7.2 4.0 12.7 54.9 5.8 M M 16000 -19.9 -3.8 285 22 11 6.9 3.8 12.3 54.1 5.5 M M 15500 -18.9 -2.0 285 21 11 6.8 3.7 11.8 53.2 5.0 M M 15000 -17.9 -0.2 285 20 10 6.8 3.7 11.3 52.3 4.6 M M 14500 -16.8 1.8 290 19 10 6.9 3.8 10.8 51.4 4.2 M M 14000 -15.8 3.6 290 18 9 7.0 3.8 10.3 50.6 3.8 M M 13500 -14.7 5.5 290 17 9 7.2 4.0 9.9 49.8 3.4 M M 13000 -13.6 7.5 290 16 8 7.1 3.9 9.5 49.1 3.1 M M 12500 -12.7 9.1 290 14 7 6.1 3.4 8.9 48.1 2.6 M M 12000 -11.8 10.8 295 12 6 6.5 3.6 8.4 47.1 2.1 M M 11500 -10.6 12.9 295 12 6 8.4 4.6 8.0 46.5 1.8 M M 11000 -9.4 15.1 295 12 6 7.8 4.3 7.8 46.1 1.6 M M 10500 -8.4 16.9 295 12 6 5.7 3.2 7.3 45.1 1.1 M M 10250 -8.0 17.6 300 12 6 6.6 3.6 7.0 44.6 0.8 M M 10000 -7.5 18.5 300 12 6 3.8 2.1 6.7 44.1 0.5 M M 9750 -7.3 18.9 300 13 7 3.1 1.7 6.1 43.0 -0.1 311 1.6 9500 -7.0 19.4 295 13 7 5.4 3.0 5.7 42.3 -0.4 293 1.5 9250 -6.6 20.1 295 14 7 4.9 2.7 5.4 41.6 -0.8 275 1.4 9000 -6.3 20.7 295 15 8 3.7 2.0 5.0 40.9 -1.2 257 1.3 8750 -6.1 21.0 295 16 8 1.9 1.0 4.4 39.9 -1.8 245 1.2 8500 -6.0 21.2 290 16 8 1.7 0.9 3.8 38.8 -2.4 234 1.2 8250 -5.9 21.4 290 16 8 1.7 0.9 3.2 37.7 -3.0 223 1.1 8000 -5.8 21.6 290 15 8 1.6 0.9 2.5 36.5 -3.6 212 1.1 7750 -5.7 21.7 290 14 7 1.6 0.9 1.9 35.4 -4.3 202 1.0 7500 -5.5 22.1 285 12 6 1.8 1.0 1.3 34.3 -4.9 191 1.0 7250 -5.4 22.3 285 11 6 2.3 1.3 0.7 33.2 -5.5 179 0.9 7000 -5.2 22.6 280 9 5 2.9 1.6 0.1 32.2 -6.1 166 0.8 6750 -5.0 23.0 275 7 4 2.3 1.3 -0.4 31.3 -6.6 153 0.8 6500 -4.9 23.2 270 5 3 1.2 0.7 -1.0 30.2 -7.2 142 0.7 6250 -4.9 23.2 255 4 2 0.3 0.2 -1.7 28.9 -8.0 133 0.7 6000 -4.8 23.4 230 3 2 1.6 0.9 -2.4 27.7 -8.7 125 0.6 5750 -4.8 23.4 200 4 2 -3.1 -1.7 -3.1 26.5 -9.4 116 0.6 5500 -5.7 21.7 185 4 2 -24.0 -13.2 -4.7 23.5 -11.1 137 0.7 * * * * * * Numerical weather prediction model forecast data valid * * * * * * 02/24/2019 at 0800 MST | 02/24/2019 at 1100 MST | CAPE... 0.0 LI... +7.9 | CAPE... 0.0 LI... +7.7 CINH... 0.0 K Index... -20.4 | CINH... 0.0 K Index... -17.4 | 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 -56.5 -69.7 265 36 19 -0.2 -0.1 | -56.8 -70.2 265 37 19 -0.1 -0.0 45000 -56.9 -70.4 265 43 22 -0.2 -0.1 | -57.0 -70.6 265 44 23 -0.1 -0.0 40000 -61.2 -78.2 270 47 24 -3.5 -1.9 | -62.1 -79.8 270 48 25 -4.1 -2.2 38000 -63.0 -81.4 275 48 25 2.1 1.2 | -64.1 -83.4 270 50 26 3.7 2.0 36000 -61.4 -78.5 275 49 25 2.7 1.5 | -61.7 -79.1 270 52 27 3.9 2.2 34000 -59.7 -75.5 275 50 26 2.7 1.5 | -59.4 -74.9 270 53 28 3.8 2.1 32000 -56.0 -68.8 275 47 24 7.2 3.9 | -55.0 -67.0 270 49 25 7.0 3.8 30000 -51.2 -60.2 275 43 22 7.6 4.2 | -50.8 -59.4 270 44 23 7.4 4.1 29000 -48.8 -55.8 275 41 21 8.2 4.5 | -48.5 -55.3 270 42 22 7.8 4.3 28000 -46.3 -51.3 275 40 21 8.2 4.5 | -46.2 -51.2 270 40 21 7.8 4.3 27000 -43.8 -46.8 275 39 20 8.2 4.5 | -43.8 -46.8 270 38 19 7.8 4.3 26000 -41.5 -42.7 280 38 20 7.7 4.2 | -41.5 -42.7 275 36 18 7.8 4.3 25000 -39.2 -38.6 280 37 19 7.6 4.2 | -39.2 -38.6 275 34 18 7.8 4.3 24000 -36.9 -34.4 280 36 18 7.6 4.2 | -36.9 -34.4 280 33 17 7.8 4.3 23000 -34.6 -30.3 280 34 18 7.5 4.1 | -34.5 -30.1 280 31 16 7.9 4.3 22000 -32.4 -26.3 280 33 17 7.5 4.1 | -32.2 -26.0 285 30 15 7.9 4.3 21000 -30.1 -22.2 285 32 16 7.6 4.1 | -29.8 -21.6 285 29 15 8.0 4.4 20000 -28.0 -18.4 285 30 16 7.1 3.9 | -27.6 -17.7 285 27 14 7.1 3.9 19500 -26.9 -16.4 285 29 15 7.1 3.9 | -26.5 -15.7 285 26 13 7.1 3.9 19000 -25.8 -14.4 285 29 15 7.2 3.9 | -25.5 -13.9 285 25 13 7.1 3.9 18500 -24.7 -12.5 285 28 14 7.2 4.0 | -23.9 -11.0 285 23 12 6.9 3.8 18000 -23.7 -10.7 285 27 14 6.5 3.6 | -22.9 -9.2 285 22 11 6.6 3.6 17500 -22.3 -8.1 285 25 13 6.5 3.6 | -21.9 -7.4 285 21 11 6.7 3.7 17000 -21.4 -6.5 285 23 12 5.3 2.9 | -20.9 -5.6 285 20 10 6.3 3.5 16500 -20.6 -5.1 285 21 11 5.4 2.9 | -20.0 -4.0 285 18 9 6.3 3.5 16000 -19.8 -3.6 285 19 10 5.5 3.0 | -19.0 -2.2 285 17 9 6.0 3.3 15500 -18.9 -2.0 285 17 9 5.6 3.1 | -18.1 -0.6 285 16 8 5.9 3.2 15000 -18.1 -0.6 285 15 8 5.6 3.1 | -17.3 0.9 285 14 7 5.9 3.2 14500 -17.2 1.0 285 14 7 5.7 3.1 | -16.4 2.5 285 13 7 6.0 3.3 14000 -16.4 2.5 285 12 6 5.9 3.3 | -15.5 4.1 285 12 6 5.9 3.2 13500 -15.4 4.3 285 11 6 6.7 3.7 | -14.6 5.7 285 11 6 5.8 3.2 13000 -14.4 6.1 285 10 5 6.7 3.7 | -13.8 7.2 285 10 5 5.8 3.2 12500 -13.4 7.9 290 10 5 6.6 3.6 | -12.9 8.8 285 9 5 6.1 3.3 12000 -12.5 9.5 290 10 5 6.6 3.6 | -12.0 10.4 285 8 4 6.1 3.3 11500 -11.5 11.3 290 9 5 6.4 3.5 | -11.1 12.0 285 8 4 6.2 3.4 11000 -10.5 13.1 290 8 4 6.8 3.7 | -10.1 13.8 285 8 4 6.2 3.4 10500 -9.4 15.1 290 9 4 7.8 4.3 | -9.2 15.4 285 7 4 6.0 3.3 10250 -8.8 16.2 290 9 5 8.9 4.9 | -8.8 16.2 285 7 4 6.2 3.4 10000 -8.2 17.2 295 9 5 4.5 2.5 | -8.3 17.1 285 8 4 5.4 3.0 9750 -8.0 17.6 290 9 5 4.2 2.3 | -8.0 17.6 285 8 4 5.0 2.7 9500 -7.5 18.5 295 10 5 8.3 4.5 | -7.6 18.3 280 8 4 5.5 3.0 9250 -6.9 19.6 295 10 5 7.1 3.9 | -7.2 19.0 280 8 4 5.3 2.9 9000 -6.5 20.3 295 11 6 3.1 1.7 | -6.8 19.8 280 8 4 5.3 2.9 8750 -6.4 20.5 290 10 5 1.5 0.8 | -6.4 20.5 275 7 3 4.8 2.7 8500 -6.2 20.8 290 10 5 3.6 2.0 | -6.1 21.0 270 6 3 4.4 2.4 8250 -6.0 21.2 290 9 5 2.5 1.4 | -5.8 21.6 265 5 3 5.0 2.8 8000 -5.8 21.6 290 9 5 1.9 1.1 | -5.3 22.5 255 4 2 6.1 3.3 7750 -5.7 21.7 285 8 4 1.6 0.9 | -4.9 23.2 240 3 2 5.7 3.1 7500 -5.6 21.9 285 8 4 1.4 0.8 | -4.5 23.9 220 3 1 5.3 2.9 7250 -5.5 22.1 280 7 3 2.3 1.2 | -4.1 24.6 205 3 1 6.3 3.5 7000 -5.3 22.5 270 6 3 3.1 1.7 | -3.5 25.7 185 3 1 7.8 4.3 6750 -5.1 22.8 260 5 2 2.0 1.1 | -3.0 26.6 170 3 2 4.6 2.5 6500 -5.0 23.0 245 4 2 0.5 0.3 | -2.7 27.1 165 4 2 5.4 3.0 6250 -5.0 23.0 225 4 2 0.3 0.1 | -2.1 28.2 165 4 2 9.4 5.2 6000 -5.0 23.0 210 5 2 0.3 0.2 | -1.5 29.3 165 3 2 8.6 4.7 5750 -5.0 23.0 200 6 3 0.3 0.2 | -0.9 30.4 165 3 2 9.6 5.3 5500 -5.1 22.8 195 5 3 -6.2 -3.4 | -0.1 31.8 165 3 2 14.0 7.7 02/24/2019 at 1400 MST | 02/24/2019 at 1700 MST | CAPE... 0.0 LI... +7.0 | CAPE... 0.0 LI... +5.5 CINH... 0.0 K Index... -7.6 | CINH... 0.0 K Index... -3.9 | 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 -57.6 -71.7 270 38 20 -0.5 -0.3 | -58.3 -72.9 270 39 20 -0.1 -0.1 45000 -58.5 -73.3 270 43 22 -0.5 -0.3 | -58.5 -73.3 270 43 22 -0.1 -0.1 40000 -62.7 -80.9 265 46 24 -3.2 -1.8 | -62.7 -80.9 265 44 23 -3.3 -1.8 38000 -64.0 -83.2 265 48 24 5.3 2.9 | -63.9 -83.0 265 44 22 5.6 3.1 36000 -61.4 -78.5 265 48 25 4.4 2.4 | -61.0 -77.8 265 42 22 4.8 2.6 34000 -58.8 -73.8 265 49 25 4.2 2.3 | -58.1 -72.6 265 40 21 4.6 2.5 32000 -54.9 -66.8 265 46 24 6.9 3.8 | -54.2 -65.6 270 37 19 6.9 3.8 30000 -50.3 -58.5 265 41 21 7.3 4.0 | -49.5 -57.1 275 33 17 7.2 4.0 29000 -48.0 -54.4 265 40 20 7.6 4.2 | -47.3 -53.1 275 32 16 7.3 4.0 28000 -45.7 -50.3 270 38 19 7.6 4.2 | -45.1 -49.2 275 31 16 7.3 4.0 27000 -43.5 -46.3 270 36 19 7.5 4.1 | -42.9 -45.2 280 30 15 7.3 4.0 26000 -41.0 -41.8 270 34 18 8.6 4.7 | -40.6 -41.1 280 29 15 8.0 4.4 25000 -38.5 -37.3 270 32 17 8.6 4.7 | -38.2 -36.8 280 28 14 8.0 4.4 24000 -35.9 -32.6 270 30 15 8.6 4.7 | -35.8 -32.4 280 27 14 8.0 4.4 23000 -33.4 -28.1 275 27 14 7.8 4.3 | -33.3 -27.9 280 26 13 8.5 4.7 22000 -31.1 -24.0 275 24 12 7.8 4.3 | -30.8 -23.4 280 24 13 8.5 4.7 21000 -28.7 -19.7 280 21 11 7.8 4.3 | -28.2 -18.8 280 23 12 8.6 4.7 20000 -26.3 -15.3 285 21 11 8.2 4.5 | -25.8 -14.4 280 21 11 7.8 4.3 19500 -25.1 -13.2 285 21 11 8.2 4.5 | -24.7 -12.5 280 20 10 7.8 4.3 19000 -23.9 -11.0 285 21 11 8.2 4.5 | -23.5 -10.3 275 19 10 7.8 4.3 18500 -22.7 -8.9 290 21 11 8.3 4.6 | -22.3 -8.1 275 18 9 7.6 4.2 18000 -21.5 -6.7 290 20 10 7.0 3.9 | -21.0 -5.8 275 17 9 9.7 5.3 17500 -20.4 -4.7 290 19 10 7.1 3.9 | -19.6 -3.3 270 16 8 9.5 5.2 17000 -19.4 -2.9 290 18 9 7.3 4.0 | -18.2 -0.8 270 15 8 8.4 4.6 16500 -17.7 0.1 285 17 9 7.6 4.1 | -17.0 1.4 275 14 7 7.7 4.2 16000 -16.6 2.1 285 17 9 6.4 3.5 | -15.9 3.4 280 13 7 7.3 4.0 15500 -15.7 3.7 285 16 8 6.0 3.3 | -14.9 5.2 280 13 7 5.8 3.2 15000 -14.8 5.4 280 16 8 5.6 3.1 | -14.1 6.6 275 13 7 5.9 3.3 14500 -14.1 6.6 280 16 8 5.2 2.8 | -12.8 9.0 275 14 7 5.4 3.0 14000 -13.3 8.1 275 17 8 5.0 2.7 | -12.1 10.2 275 14 7 5.2 2.9 13500 -12.6 9.3 275 16 8 4.5 2.5 | -11.3 11.7 270 15 8 4.8 2.7 13000 -11.9 10.6 270 16 8 4.5 2.4 | -10.6 12.9 270 15 8 5.0 2.7 12500 -11.3 11.7 270 15 8 4.1 2.2 | -9.9 14.2 265 15 8 5.3 2.9 12000 -10.7 12.7 265 13 7 4.5 2.4 | -9.1 15.6 265 15 8 5.4 2.9 11500 -9.9 14.2 260 12 6 6.4 3.5 | -8.3 17.1 265 13 7 5.6 3.0 11000 -9.0 15.8 255 11 6 6.2 3.4 | -7.5 18.5 265 12 6 5.8 3.2 10500 -8.1 17.4 250 9 5 5.7 3.1 | -6.5 20.3 265 10 5 6.4 3.5 10250 -7.6 18.3 245 8 4 6.2 3.4 | -6.0 21.2 260 9 5 7.1 3.9 10000 -7.2 19.0 240 7 4 4.7 2.6 | -5.5 22.1 260 8 4 4.6 2.5 9750 -6.9 19.6 235 7 4 5.6 3.1 | -5.3 22.5 260 8 4 5.5 3.0 9500 -6.3 20.7 230 7 3 7.8 4.3 | -4.7 23.5 255 7 4 8.7 4.8 9250 -5.8 21.6 220 6 3 7.2 4.0 | -4.1 24.6 255 6 3 7.9 4.3 9000 -5.2 22.6 210 6 3 7.1 3.9 | -3.5 25.7 250 5 3 7.2 3.9 8750 -4.7 23.5 205 6 3 7.2 4.0 | -3.0 26.6 245 5 2 6.9 3.8 8500 -4.1 24.6 195 6 3 7.7 4.2 | -2.4 27.7 235 4 2 7.6 4.2 8250 -3.5 25.7 185 6 3 7.6 4.2 | -1.9 28.6 225 4 2 7.2 4.0 8000 -2.9 26.8 175 5 3 7.9 4.3 | -1.3 29.7 215 4 2 6.9 3.8 7750 -2.4 27.7 165 5 3 7.1 3.9 | -0.8 30.6 205 3 2 6.3 3.5 7500 -1.9 28.6 160 5 3 6.3 3.4 | -0.4 31.3 195 3 2 5.7 3.1 7250 -1.4 29.5 155 5 3 8.1 4.4 | 0.0 32.0 190 4 2 6.8 3.7 7000 -0.7 30.7 150 5 2 9.7 5.3 | 0.5 32.9 180 4 2 7.5 4.1 6750 -0.1 31.8 150 5 2 8.4 4.6 | 1.1 34.0 170 4 2 7.8 4.3 6500 0.5 32.9 150 4 2 9.0 4.9 | 1.7 35.1 165 4 2 8.7 4.8 6250 1.3 34.3 150 4 2 10.8 5.9 | 2.3 36.1 165 4 2 8.6 4.7 6000 2.1 35.8 150 4 2 10.9 6.0 | 3.0 37.4 160 4 2 9.1 5.0 5750 2.9 37.2 150 4 2 10.7 5.9 | 3.6 38.5 155 3 2 7.8 4.3 5500 3.7 38.7 155 4 2 12.4 6.8 | 4.0 39.2 150 2 1 2.8 1.5 ________________________________________________________________________________ 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