Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
760 UXUS97 KPUB 271211 SRGPUB Soaring Forecast National Weather Service Pueblo, Colorado 0611 MDT Monday, May 27, 2024 This forecast is for Villa Grove, CO for Monday, May 27, 2024: If the trigger temperature of 51.4 F/10.8 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1309 ft/min (6.6 m/s) Maximum height of thermals.................. 23203 ft MSL (14235 ft AGL) Forecast maximum temperature................... 71.0 F/22.1 C Time of trigger temperature.................... 0845 MDT Time of overdevelopment........................ 1700 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 18724 ft MSL (9756 ft AGL) Thermal soaring outlook for Tuesday 05/28...... Excellent Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 05:43:43 / 20:17:58 MDT Total possible sunshine........... 14 hr 34 min 15 sec (874 min 15 sec) Altitude of sun at 13:00:51 MDT... 73.20 degrees Upper air data from numerical model forecast valid on 05/27/2024 at 0600 MDT Freezing level.................. 12470 ft MSL (3502 ft AGL) Convective condensation level... 17892 ft MSL (8924 ft AGL) Lifted condensation level....... 19740 ft MSL (10772 ft AGL) Lifted index.................... -3.9 K index......................... -1.6 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 -57.4 -71.3 265 46 24 0.8 0.4 M M M M M 45000 -56.5 -69.7 270 50 26 -1.0 -0.5 M M M M M 40000 -58.0 -72.4 270 45 23 -1.6 -0.9 M M M M M 38000 -55.3 -67.5 270 41 21 5.4 2.9 M M M M M 36000 -52.1 -61.8 275 38 19 5.4 3.0 M M M M M 34000 -47.8 -54.0 270 34 17 7.3 4.0 M M M M M 32000 -43.4 -46.1 270 31 16 7.2 4.0 M M M M M 30000 -38.6 -37.5 265 29 15 8.6 4.7 25.2 77.3 2.8 M M 29000 -36.0 -32.8 265 29 15 8.6 4.7 24.7 76.5 2.4 M M 28000 -33.4 -28.1 265 29 15 8.6 4.7 24.4 75.9 2.2 M M 27000 -30.9 -23.6 270 29 15 8.4 4.6 23.9 75.0 1.8 M M 26000 -28.4 -19.1 270 29 15 8.4 4.6 23.4 74.0 1.4 M M 25000 -25.8 -14.4 275 30 15 8.4 4.6 22.9 73.3 1.0 M M 24000 -23.4 -10.1 275 29 15 7.7 4.2 22.3 72.2 0.6 M M 23000 -21.1 -6.0 280 27 14 7.7 4.2 21.6 70.8 -0.1 1291 6.6 22000 -18.8 -1.8 280 25 13 7.7 4.2 20.9 69.6 -0.7 1193 6.1 21000 -16.5 2.3 280 23 12 7.6 4.2 20.2 68.3 -1.4 1094 5.6 20000 -14.3 6.3 275 22 12 7.6 4.2 19.4 67.0 -2.1 996 5.1 19500 -13.1 8.4 275 22 11 7.6 4.2 19.1 66.4 -2.4 947 4.8 19000 -12.0 10.4 275 22 11 7.3 4.0 18.8 65.8 -2.7 898 4.6 18500 -11.0 12.2 275 21 11 6.5 3.6 18.3 64.9 -3.1 853 4.3 18000 -10.0 14.0 275 20 10 6.6 3.6 17.7 63.9 -3.6 809 4.1 17500 -9.0 15.8 280 20 10 6.0 3.3 17.2 62.9 -4.2 765 3.9 17000 -8.1 17.4 285 20 10 6.0 3.3 16.6 61.8 -4.8 723 3.7 16500 -7.2 19.0 290 20 10 5.6 3.1 16.0 60.7 -5.3 682 3.5 16000 -6.5 20.3 295 21 11 5.1 2.8 15.2 59.4 -6.1 644 3.3 15500 -5.3 22.5 295 21 11 5.4 3.0 14.1 57.4 -7.2 588 3.0 15000 -4.5 23.9 300 22 11 5.6 3.1 13.4 56.2 -7.9 550 2.8 14500 -3.8 25.2 300 22 11 6.1 3.4 12.8 55.0 -8.7 511 2.6 14000 -2.8 27.0 300 21 11 6.4 3.5 12.2 54.0 -9.3 469 2.4 13500 -1.9 28.6 300 20 10 6.2 3.4 11.7 53.1 -9.9 427 2.2 13000 -1.0 30.2 300 19 10 7.6 4.2 11.2 52.2 -10.5 384 2.0 12500 0.1 32.2 300 18 9 7.9 4.3 11.0 51.7 -10.9 336 1.7 12000 1.2 34.2 295 17 9 7.5 4.1 10.6 51.0 -11.3 290 1.5 11750 1.8 35.2 295 17 9 9.2 5.0 10.5 50.9 -11.5 264 1.3 11500 2.4 36.3 295 16 8 9.3 5.1 10.4 50.8 -11.6 237 1.2 11250 3.1 37.6 290 16 8 8.3 4.6 10.4 50.7 -11.7 210 1.1 11000 3.7 38.7 290 15 8 7.4 4.1 10.2 50.4 -11.9 185 0.9 10750 4.2 39.6 290 15 8 8.9 4.9 10.1 50.2 -12.1 161 0.8 10500 4.9 40.8 285 14 7 9.5 5.2 10.1 50.1 -12.1 132 0.7 10250 5.5 41.9 285 14 7 6.2 3.4 9.9 49.9 -12.3 107 0.5 10000 5.9 42.6 285 13 7 3.9 2.1 9.6 49.2 -12.7 88 0.4 9750 6.3 43.3 280 12 6 6.6 3.6 9.2 48.5 -13.1 70 0.4 9500 6.7 44.1 275 11 6 1.0 0.5 8.9 48.0 -13.4 49 0.2 9250 6.1 43.0 270 8 4 -20.3 -11.2 7.5 45.4 -14.8 61 0.3 9000 4.3 39.7 255 4 2 -19.8 -10.9 4.9 40.8 -17.4 108 0.5 8750 M M M M M M M M M M M M 8500 M M M M M M M M M M M M 8250 M M M M M M M M M M M M 8000 M M M M M M M M M M M M * * * * * * Numerical weather prediction model forecast data valid * * * * * * 05/27/2024 at 0900 MDT | 05/27/2024 at 1200 MDT | CAPE... 0.0 LI... +2.1 | CAPE... +35.7 LI... +0.8 CINH... 0.0 K Index... -2.1 | CINH... -1.9 K Index... +1.0 | 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 -56.8 -70.2 265 43 22 1.1 0.6 | -56.9 -70.4 265 41 21 0.7 0.4 45000 -55.7 -68.3 270 45 23 -1.4 -0.8 | -56.2 -69.2 265 44 22 -1.3 -0.7 40000 -57.9 -72.2 270 44 22 -0.1 -0.1 | -58.2 -72.8 265 44 22 0.6 0.3 38000 -54.7 -66.5 270 43 22 5.9 3.3 | -54.8 -66.6 265 44 22 6.0 3.3 36000 -51.1 -60.0 270 42 21 5.9 3.3 | -51.3 -60.3 265 43 22 6.0 3.3 34000 -47.3 -53.1 270 39 20 6.7 3.7 | -47.3 -53.1 265 40 21 7.1 3.9 32000 -43.3 -45.9 270 34 17 6.7 3.7 | -43.1 -45.6 270 34 18 7.1 3.9 30000 -38.9 -38.0 275 30 16 8.0 4.4 | -38.6 -37.5 270 29 15 7.9 4.4 29000 -36.5 -33.7 275 29 15 8.1 4.4 | -36.2 -33.2 270 27 14 7.9 4.4 28000 -34.1 -29.4 275 28 14 8.1 4.4 | -33.2 -27.8 275 24 12 8.0 4.4 27000 -31.1 -24.0 275 27 14 8.0 4.4 | -30.9 -23.6 275 23 12 7.8 4.3 26000 -28.7 -19.7 275 27 14 8.0 4.4 | -28.6 -19.5 280 23 12 7.8 4.3 25000 -26.3 -15.3 275 27 14 8.0 4.4 | -26.2 -15.2 280 23 12 7.8 4.3 24000 -23.9 -11.0 275 26 13 7.9 4.3 | -23.9 -11.0 280 23 12 7.7 4.2 23000 -21.5 -6.7 275 24 13 7.9 4.3 | -21.6 -6.9 280 22 11 7.7 4.2 22000 -19.2 -2.6 275 23 12 8.9 4.4 | -19.3 -2.7 280 22 11 7.7 4.2 21000 -16.9 1.6 275 21 11 7.7 4.2 | -17.0 1.4 280 20 10 7.7 4.2 20000 -14.6 5.7 280 19 10 7.7 4.2 | -14.7 5.5 285 17 9 7.7 4.2 19500 -13.4 7.9 280 18 9 7.6 4.2 | -13.6 7.5 290 16 8 7.7 4.2 19000 -12.3 9.9 280 17 9 7.0 3.8 | -12.4 9.7 290 15 8 6.6 3.6 18500 -11.3 11.7 285 17 9 6.3 3.5 | -11.6 11.1 295 14 7 5.9 3.3 18000 -10.4 13.3 290 17 9 6.4 3.5 | -10.7 12.7 300 14 7 5.9 3.2 17500 -9.5 14.9 295 18 9 5.3 2.9 | -9.9 14.2 300 14 7 5.3 2.9 17000 -8.7 16.3 300 19 10 5.4 3.0 | -9.1 15.6 305 14 7 5.4 3.0 16500 -7.9 17.8 305 20 10 5.4 3.0 | -8.3 17.1 305 15 8 6.8 3.7 16000 -7.2 19.0 305 21 11 5.4 3.0 | -7.3 18.9 300 14 7 7.5 4.1 15500 -6.4 20.5 305 21 11 5.6 3.0 | -6.3 20.7 300 13 7 8.2 4.5 15000 -5.5 22.1 305 21 11 6.1 3.4 | -5.0 23.0 295 12 6 9.2 5.0 14500 -4.7 23.5 305 21 11 6.2 3.4 | -3.6 25.5 290 11 6 8.2 4.5 14000 -3.7 25.3 305 20 10 7.1 3.9 | -1.6 29.1 285 10 5 10.0 5.5 13500 -2.3 27.9 305 18 10 7.1 3.9 | -0.1 31.8 285 9 5 9.8 5.4 13000 -1.3 29.7 305 17 9 7.9 4.3 | 1.4 34.5 285 9 5 10.0 5.5 12500 -0.1 31.8 305 15 8 8.2 4.5 | 2.8 37.0 285 8 4 9.8 5.4 12000 1.1 34.0 300 13 7 8.9 4.9 | 4.3 39.7 285 8 4 9.9 5.4 11750 1.8 35.2 300 12 6 9.1 5.0 | 5.0 41.0 285 8 4 10.9 6.0 11500 2.4 36.3 295 11 6 9.0 5.0 | 5.8 42.4 285 8 4 10.4 5.7 11250 3.1 37.6 290 10 5 9.0 5.0 | 6.6 43.9 285 8 4 9.6 5.3 11000 3.8 38.8 290 9 5 8.5 4.7 | 7.3 45.1 285 7 4 9.2 5.0 10750 4.4 39.9 285 8 4 10.3 5.6 | 8.0 46.4 285 7 4 10.2 5.6 10500 5.3 41.5 280 8 4 11.5 6.3 | 8.8 47.8 285 7 4 11.2 6.1 10250 6.1 43.0 275 7 4 10.1 5.5 | 9.6 49.3 285 7 3 10.9 6.0 10000 6.8 44.2 275 7 4 10.1 5.6 | 10.4 50.7 285 7 3 11.6 6.3 9750 7.5 45.5 270 7 3 9.4 5.2 | 11.3 52.3 290 6 3 9.4 5.1 9500 8.3 46.9 270 6 3 13.5 7.4 | 12.0 53.6 290 6 3 14.9 8.2 9250 9.7 49.5 270 6 3 23.5 12.9 | 13.8 56.8 290 6 3 32.9 18.0 9000 11.2 52.2 265 6 3 11.8 6.5 | 16.0 60.8 285 6 3 16.4 9.0 8750 M M M M M M M | M M M M M M M 8500 M M M M M M M | M M M M M M M 8250 M M M M M M M | M M M M M M M 8000 M M M M M M M | M M M M M M M 05/27/2024 at 1500 MDT | 05/27/2024 at 1800 MDT | CAPE... +196.1 LI... -1.1 | CAPE... +172.3 LI... -0.9 CINH... -0.7 K Index... +19.9 | CINH... -14.1 K Index... +21.8 | 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 -57.2 -71.0 265 40 21 0.4 0.2 | -56.5 -69.7 270 40 20 0.6 0.3 45000 -56.9 -70.4 265 43 22 -1.3 -0.7 | -56.2 -69.2 270 41 21 -1.9 -1.1 40000 -58.9 -74.0 270 43 22 0.9 0.5 | -59.2 -74.6 280 38 19 -0.1 -0.0 38000 -55.3 -67.5 270 42 22 6.3 3.5 | -55.8 -68.4 275 39 20 6.2 3.4 36000 -51.6 -60.9 270 41 21 6.3 3.5 | -52.0 -61.6 270 40 20 6.2 3.4 34000 -47.3 -53.1 270 39 20 7.6 4.1 | -47.7 -53.9 270 40 21 7.9 4.3 32000 -42.8 -45.0 270 37 19 7.6 4.1 | -43.0 -45.4 265 41 21 7.9 4.3 30000 -38.3 -36.9 270 31 16 7.4 4.1 | -38.3 -36.9 265 38 19 7.8 4.3 29000 -36.1 -33.0 270 27 14 7.4 4.1 | -35.4 -31.7 265 34 17 7.8 4.3 28000 -33.3 -27.9 270 23 12 7.4 4.1 | -33.1 -27.6 265 31 16 7.8 4.3 27000 -31.0 -23.8 275 22 11 7.8 4.3 | -30.8 -23.4 270 28 15 7.6 4.2 26000 -28.7 -19.7 275 21 11 7.8 4.3 | -28.5 -19.3 270 26 13 7.6 4.2 25000 -26.3 -15.3 280 21 11 7.8 4.3 | -26.2 -15.2 275 24 12 7.6 4.2 24000 -24.1 -11.4 280 21 11 7.3 4.0 | -24.1 -11.4 280 22 11 6.8 3.7 23000 -21.9 -7.4 280 20 10 7.3 4.0 | -22.1 -7.8 280 19 10 6.9 3.8 22000 -19.7 -3.5 280 19 10 7.3 4.0 | -20.1 -4.2 285 17 9 6.7 3.7 21000 -17.6 0.3 280 18 9 7.2 4.0 | -17.7 0.1 285 15 8 8.6 4.7 20000 -15.5 4.1 280 16 8 7.4 4.0 | -15.1 4.8 290 12 6 8.7 4.8 19500 -14.4 6.1 280 15 8 7.4 4.1 | -13.9 7.0 290 10 5 8.8 4.8 19000 -13.3 8.1 275 14 7 8.1 4.5 | -12.6 9.3 295 9 5 8.4 4.6 18500 -12.1 10.2 275 13 7 8.4 4.6 | -11.4 11.5 295 9 4 8.2 4.5 18000 -10.9 12.4 275 12 6 8.6 4.7 | -10.2 13.6 295 8 4 8.4 4.6 17500 -9.6 14.7 275 12 6 9.4 5.1 | -8.9 16.0 295 8 4 9.4 5.2 17000 -8.2 17.2 275 11 6 9.3 5.1 | -7.5 18.5 290 8 4 9.4 5.1 16500 -6.9 19.6 270 11 5 9.6 5.3 | -6.1 21.0 290 7 4 9.4 5.2 16000 -5.4 22.3 270 10 5 9.7 5.3 | -4.7 23.5 285 7 4 9.4 5.2 15500 -4.0 24.8 270 10 5 9.7 5.3 | -3.3 26.1 280 7 4 9.2 5.1 15000 -2.5 27.5 270 10 5 9.7 5.3 | -2.0 28.4 270 7 3 8.9 4.9 14500 -1.1 30.0 270 9 5 9.6 5.2 | -0.6 30.9 260 7 3 8.0 4.4 14000 1.1 34.0 270 9 5 9.8 5.4 | 0.6 33.1 250 7 4 9.1 5.0 13500 2.6 36.7 270 9 4 8.2 4.5 | 1.9 35.4 245 7 4 8.9 4.9 13000 3.9 39.0 270 8 4 10.9 6.0 | 3.9 39.0 230 8 4 9.0 4.9 12500 5.5 41.9 270 8 4 10.0 5.5 | 5.2 41.4 225 9 5 8.7 4.8 12000 6.8 44.2 270 8 4 9.9 5.4 | 6.4 43.5 220 10 5 8.9 4.9 11750 7.7 45.9 270 8 4 11.7 6.4 | 7.1 44.8 220 10 5 10.2 5.6 11500 8.5 47.3 270 7 4 10.7 5.9 | 7.9 46.2 215 10 5 9.7 5.3 11250 9.3 48.7 270 7 4 9.6 5.3 | 8.6 47.5 215 10 5 9.4 5.2 11000 10.0 50.0 270 7 4 9.1 5.0 | 9.2 48.6 215 10 5 9.0 4.9 10750 10.7 51.3 270 7 4 10.7 5.9 | 9.9 49.8 215 10 5 10.6 5.8 10500 11.5 52.7 270 7 3 11.6 6.4 | 10.8 51.4 210 10 5 11.2 6.2 10250 12.3 54.1 270 7 3 10.4 5.7 | 11.6 52.9 210 10 5 9.6 5.3 10000 13.1 55.6 270 6 3 10.6 5.8 | 12.3 54.1 210 10 5 9.5 5.2 9750 13.9 57.0 270 6 3 9.2 5.0 | 13.0 55.4 210 10 5 9.4 5.2 9500 14.6 58.3 270 6 3 14.1 7.8 | 13.7 56.7 210 10 5 12.1 6.7 9250 16.2 61.2 270 6 3 29.1 15.9 | 14.8 58.6 205 9 4 17.4 9.6 9000 18.3 64.9 265 5 3 18.9 10.4 | 16.0 60.8 205 7 4 10.7 5.9 8750 M M M M M M M | M M M M M M M 8500 M M M M M M M | M M M M M M M 8250 M M M M M M M | M M M M M M M 8000 M M M M M M M | M M M M M M M ________________________________________________________________________________ This product is issued twice per day, once by approximately 0630 MST/0730 MDT (1330 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 Villa Grove, Colorado at: North Latitude: 38 deg 16 min 03 sec West Longitude: 105 deg 53 min 37 sec Elevation: 7986 feet (2434 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. CIN (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