Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
997 UXUS97 KPUB 281214 SRGPUB Soaring Forecast National Weather Service Pueblo, Colorado 0614 MDT Friday, June 28, 2024 This forecast is for Villa Grove, CO for Friday, June 28, 2024: If the trigger temperature of 66.6 F/19.2 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1303 ft/min (6.6 m/s) Maximum height of thermals.................. 22648 ft MSL (13659 ft AGL) Forecast maximum temperature................... 82.0 F/28.2 C Time of trigger temperature.................... 0930 MDT Time of overdevelopment........................ 1500 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 19087 ft MSL (10099 ft AGL) Thermal soaring outlook for Saturday 06/29..... Excellent Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 05:42:59 / 20:31:06 MDT Total possible sunshine........... 14 hr 48 min 7 sec (888 min 7 sec) Altitude of sun at 13:07:02 MDT... 74.88 degrees Upper air data from numerical model forecast valid on 06/28/2024 at 0600 MDT Freezing level.................. 16496 ft MSL (7507 ft AGL) Convective condensation level... 16493 ft MSL (7504 ft AGL) Lifted condensation level....... 18682 ft MSL (9693 ft AGL) Lifted index.................... -5.5 K index......................... +22.4 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 -64.7 -84.5 245 46 24 2.6 1.4 M M M M M 45000 -58.6 -73.5 240 62 32 6.4 3.5 M M M M M 40000 -48.7 -55.7 240 70 36 7.6 4.2 M M M M M 38000 -44.1 -47.4 245 70 36 7.6 4.2 M M M M M 36000 -39.5 -39.1 245 71 37 7.8 4.3 M M M M M 34000 -35.6 -32.1 250 66 34 6.4 3.5 M M M M M 32000 -31.2 -24.2 250 59 30 6.5 3.6 M M M M M 30000 -27.5 -17.5 250 53 27 6.3 3.4 36.9 98.5 7.3 M M 29000 -25.6 -14.1 250 50 26 6.3 3.4 35.7 96.2 6.4 M M 28000 -23.7 -10.7 250 46 24 5.7 3.1 34.5 94.1 5.5 M M 27000 -22.1 -7.8 255 42 21 5.4 3.0 32.7 90.9 4.1 M M 26000 -20.6 -5.1 255 37 19 5.5 3.0 31.2 88.1 2.8 M M 25000 -19.0 -2.2 255 32 17 5.7 3.1 29.8 85.6 1.5 M M 24000 -16.8 1.8 255 29 15 8.1 4.4 29.0 84.1 0.8 M M 23000 -14.4 6.1 260 26 14 8.1 4.5 28.4 83.0 0.2 M M 22000 -12.0 10.4 265 24 12 8.2 4.5 27.9 82.2 -0.3 1241 6.3 21000 -10.0 14.0 270 21 11 6.8 3.8 26.9 80.4 -1.2 1149 5.8 20000 -8.0 17.6 270 19 10 6.9 3.8 25.9 78.7 -2.1 1059 5.4 19500 -7.0 19.4 270 18 9 6.9 3.8 25.5 77.9 -2.6 1014 5.2 19000 -5.9 21.4 270 17 9 7.3 4.0 25.1 77.1 -3.0 969 4.9 18500 -4.8 23.4 270 16 8 7.4 4.1 24.7 76.4 -3.4 921 4.7 18000 -3.8 25.2 270 15 8 7.4 4.1 24.3 75.7 -3.8 874 4.4 17500 -2.6 27.3 270 14 7 8.0 4.4 24.3 75.1 -4.1 825 4.2 17000 -1.4 29.5 275 13 7 8.0 4.4 23.7 74.6 -4.4 775 3.9 16500 -0.3 31.5 275 13 7 7.9 4.3 23.4 74.1 -4.8 725 3.7 16000 1.4 34.5 275 13 6 7.8 4.3 22.9 73.2 -5.3 652 3.3 15500 2.6 36.7 275 13 6 7.9 4.3 22.6 72.7 -5.6 602 3.1 15000 3.7 38.7 275 13 7 8.0 4.4 22.3 72.1 -5.9 553 2.8 14500 4.8 40.6 275 13 7 6.2 3.4 21.9 71.4 -6.4 507 2.6 14000 5.7 42.3 275 15 8 6.3 3.4 21.3 70.4 -7.0 465 2.4 13500 6.6 43.9 275 16 8 6.1 3.3 20.8 69.4 -7.6 424 2.2 13000 7.4 45.3 280 19 10 5.5 3.0 20.1 68.2 -8.3 385 2.0 12500 8.1 46.6 280 21 11 5.5 3.0 19.5 67.1 -9.1 348 1.8 12000 8.9 48.0 280 24 12 6.1 3.4 18.9 66.0 -9.7 309 1.6 11750 9.3 48.7 280 25 13 6.0 3.3 18.6 65.5 -10.1 289 1.5 11500 9.8 49.6 280 26 13 5.9 3.2 18.3 65.0 -10.4 269 1.4 11250 10.2 50.4 280 27 14 6.5 3.6 18.0 64.5 -10.8 250 1.3 11000 10.6 51.1 280 27 14 7.4 4.1 17.8 64.1 -11.1 228 1.2 10750 11.1 52.0 275 27 14 5.8 3.2 17.6 63.7 -11.3 206 1.0 10500 11.5 52.7 275 26 14 6.3 3.4 17.3 63.1 -11.7 188 1.0 10250 11.9 53.4 275 26 13 1.4 0.8 17.0 62.5 -12.1 169 0.9 10000 11.6 52.9 275 24 12 -4.0 -2.2 16.0 60.8 -13.1 169 0.9 9750 11.4 52.5 270 22 11 -3.0 -1.6 15.0 59.1 -14.1 169 0.9 9500 11.1 52.0 270 19 10 -2.7 -1.5 14.1 57.3 -15.2 170 0.9 9250 10.8 51.4 260 15 8 -6.8 -3.7 13.1 55.5 -16.2 171 0.9 9000 9.3 48.7 245 7 4 -42.2 -23.2 10.8 51.4 -18.5 210 1.1 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 * * * * * * 06/28/2024 at 0900 MDT | 06/28/2024 at 1200 MDT | CAPE... +487.8 LI... -2.8 | CAPE... +615.5 LI... -3.0 CINH... -55.3 K Index... +21.8 | CINH... 0.0 K Index... +10.5 | 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 -64.5 -84.1 250 47 24 2.9 1.6 | -64.8 -84.6 245 52 27 2.8 1.5 45000 -58.2 -72.8 250 65 33 6.2 3.4 | -58.5 -73.3 250 69 36 6.4 3.5 40000 -48.6 -55.5 250 72 37 7.6 4.2 | -48.7 -55.7 250 73 38 7.3 4.0 38000 -44.1 -47.4 250 72 37 7.6 4.2 | -44.3 -47.7 250 72 37 7.3 4.0 36000 -39.5 -39.1 250 72 37 7.8 4.3 | -39.9 -39.8 250 70 36 7.5 4.1 34000 -35.7 -32.3 250 64 33 6.2 3.4 | -36.2 -33.2 250 60 31 5.8 3.2 32000 -31.5 -24.7 250 54 28 6.3 3.5 | -32.3 -26.1 255 47 24 5.8 3.2 30000 -28.2 -18.8 255 44 22 5.4 3.0 | -28.5 -19.3 255 39 20 6.4 3.5 29000 -26.6 -15.9 255 39 20 5.4 3.0 | -26.6 -15.9 260 35 18 6.4 3.5 28000 -24.9 -12.8 255 34 17 6.7 3.7 | -24.6 -12.3 260 32 16 7.5 4.1 27000 -22.8 -9.0 255 32 17 7.3 4.0 | -22.3 -8.1 260 32 16 7.8 4.3 26000 -20.6 -5.1 255 31 16 7.3 4.0 | -19.9 -3.8 265 32 16 7.8 4.3 25000 -18.4 -1.1 255 30 15 7.3 4.0 | -17.6 0.3 265 31 16 7.7 4.2 24000 -16.3 2.7 260 28 15 6.7 3.7 | -15.6 3.9 265 31 16 6.7 3.7 23000 -14.3 6.3 260 27 14 6.8 3.7 | -13.5 7.7 265 30 15 6.7 3.7 22000 -12.3 9.9 260 26 13 6.7 3.7 | -11.5 11.3 265 29 15 6.5 3.6 21000 -10.5 13.1 255 23 12 6.4 3.5 | -9.9 14.2 265 29 15 5.4 3.0 20000 -8.7 16.3 255 20 10 6.7 3.7 | -8.3 17.1 260 28 15 5.5 3.0 19500 -7.8 18.0 255 18 9 6.8 3.7 | -7.5 18.5 260 28 15 5.5 3.0 19000 -6.8 19.8 250 17 9 8.3 4.6 | -6.6 20.1 260 28 14 7.5 4.1 18500 -5.5 22.1 255 17 9 8.6 4.7 | -5.4 22.3 260 28 15 7.8 4.3 18000 -4.2 24.4 260 17 9 8.5 4.7 | -4.3 24.3 260 29 15 7.8 4.3 17500 -3.0 26.6 265 18 9 8.2 4.5 | -3.2 26.2 265 28 15 7.6 4.2 17000 -1.8 28.8 270 18 9 8.3 4.5 | -2.0 28.4 270 28 14 7.6 4.2 16500 -0.1 31.8 280 20 10 7.3 4.0 | -0.4 31.3 275 27 14 7.5 4.1 16000 1.0 33.8 285 22 11 7.3 4.0 | 0.7 33.3 275 27 14 7.5 4.1 15500 2.1 35.8 290 23 12 8.2 4.5 | 1.8 35.2 280 27 14 8.8 4.8 15000 3.3 37.9 295 25 13 8.7 4.8 | 2.9 37.2 280 28 14 9.4 5.1 14500 4.3 39.7 295 27 14 6.2 3.4 | 4.0 39.2 285 28 15 7.6 4.2 14000 5.5 41.9 300 29 15 7.6 4.2 | 5.2 41.4 285 26 13 8.9 4.9 13500 6.6 43.9 300 32 16 7.6 4.2 | 6.4 43.5 285 24 12 8.6 4.7 13000 7.7 45.9 300 33 17 7.5 4.1 | 7.7 45.9 280 22 11 10.4 5.7 12500 8.8 47.8 300 33 17 7.3 4.0 | 9.2 48.6 280 21 11 10.0 5.5 12000 9.6 49.3 300 30 15 5.9 3.2 | 10.6 51.1 280 20 10 9.9 5.4 11750 10.1 50.2 300 29 15 7.4 4.1 | 11.3 52.3 280 19 10 10.7 5.9 11500 10.6 51.1 300 28 14 7.1 3.9 | 12.1 53.8 280 19 10 10.5 5.7 11250 11.0 51.8 295 26 14 3.2 1.8 | 12.9 55.2 280 19 10 10.1 5.5 11000 10.9 51.6 295 25 13 -0.1 -0.0 | 13.6 56.5 280 18 9 9.8 5.4 10750 10.9 51.6 295 23 12 1.9 1.0 | 14.4 57.9 280 18 9 10.2 5.6 10500 10.9 51.6 290 20 11 2.1 1.1 | 15.1 59.2 280 17 9 10.4 5.7 10250 11.1 52.0 285 18 9 6.3 3.4 | 15.9 60.6 280 17 9 11.0 6.0 10000 11.7 53.1 280 16 8 9.9 5.4 | 16.8 62.2 280 16 8 11.6 6.4 9750 12.4 54.3 280 15 8 8.8 4.8 | 17.6 63.7 275 16 8 11.1 6.1 9500 13.0 55.4 275 13 7 10.8 5.9 | 18.4 65.1 275 15 8 12.0 6.6 9250 14.0 57.2 275 12 6 17.6 9.7 | 19.6 67.3 275 14 7 22.7 12.4 9000 15.8 60.4 270 10 5 35.6 19.5 | 22.3 72.1 275 12 6 58.9 32.3 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 06/28/2024 at 1500 MDT | 06/28/2024 at 1800 MDT | CAPE... +490.3 LI... -2.9 | CAPE... +407.5 LI... -2.1 CINH... 0.0 K Index... +23.8 | CINH... -2.4 K Index... +26.4 | 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 -65.3 -85.5 250 58 30 2.1 1.1 | -65.3 -85.5 260 62 32 2.0 1.1 45000 -59.4 -74.9 255 77 40 6.9 3.8 | -59.8 -75.6 260 79 40 6.7 3.7 40000 -49.0 -56.2 250 79 40 6.9 3.8 | -49.6 -57.3 255 78 40 7.1 3.9 38000 -44.9 -48.8 250 74 38 6.9 3.8 | -45.4 -49.7 255 72 37 7.1 3.9 36000 -40.8 -41.4 250 70 36 6.9 3.8 | -41.1 -42.0 255 65 34 7.1 3.9 34000 -37.2 -35.0 250 58 30 5.9 3.2 | -37.1 -34.8 260 57 29 6.8 3.7 32000 -33.2 -27.8 260 43 22 6.1 3.3 | -32.5 -26.5 265 47 24 6.8 3.7 30000 -29.0 -20.2 260 37 19 7.2 3.9 | -28.6 -19.5 265 40 21 6.5 3.5 29000 -26.8 -16.2 260 34 18 7.2 3.9 | -26.7 -16.1 265 37 19 6.5 3.5 28000 -24.6 -12.3 265 32 16 8.5 4.7 | -24.6 -12.3 265 34 17 8.5 4.6 27000 -22.0 -7.6 265 31 16 8.6 4.7 | -22.1 -7.8 265 30 15 8.5 4.7 26000 -19.4 -2.9 265 31 16 8.6 4.7 | -19.5 -3.1 265 26 14 8.5 4.7 25000 -16.8 1.8 265 30 15 8.2 4.5 | -17.0 1.4 265 23 12 8.1 4.5 24000 -14.8 5.4 265 30 16 6.7 3.6 | -14.8 5.4 270 25 13 7.1 3.9 23000 -12.8 9.0 265 31 16 6.7 3.7 | -12.7 9.1 270 28 14 7.1 3.9 22000 -10.8 12.6 260 32 16 6.1 3.3 | -10.5 13.1 275 30 16 6.5 3.5 21000 -9.5 14.9 260 31 16 4.2 2.3 | -9.1 15.6 270 29 15 5.1 2.8 20000 -8.3 17.1 260 31 16 4.3 2.4 | -7.6 18.3 265 27 14 5.4 3.6 19500 -7.8 18.0 260 31 16 4.1 2.3 | -6.9 19.6 265 27 14 5.5 3.0 19000 -7.0 19.4 265 30 15 7.9 4.3 | -6.1 21.0 260 26 13 6.9 3.8 18500 -5.9 21.4 265 28 15 8.1 4.5 | -5.2 22.6 260 25 13 7.0 3.8 18000 -4.8 23.4 265 27 14 8.5 4.7 | -4.2 24.4 260 24 12 7.5 4.1 17500 -3.5 25.7 265 25 13 9.1 5.0 | -3.0 26.6 265 22 11 8.4 4.6 17000 -2.3 27.9 270 23 12 9.2 5.0 | -1.8 28.8 265 21 11 8.4 4.6 16500 -0.9 30.4 270 21 11 9.6 5.2 | 0.1 32.2 270 19 10 9.1 5.0 16000 1.2 34.2 270 20 11 9.5 5.2 | 1.4 34.5 270 18 9 9.0 5.0 15500 2.6 36.7 270 20 10 10.5 5.8 | 2.8 37.0 275 17 9 10.1 5.6 15000 4.2 39.6 270 20 10 11.0 6.0 | 4.2 39.6 275 17 9 10.4 5.7 14500 5.4 41.7 270 20 10 7.8 4.3 | 5.6 42.1 275 16 8 8.3 4.6 14000 6.9 44.4 270 20 10 9.7 5.3 | 7.0 44.6 275 16 8 9.6 5.2 13500 8.4 47.1 270 19 10 9.6 5.3 | 8.4 47.1 275 16 8 8.9 4.9 13000 9.9 49.8 270 19 10 10.4 5.7 | 9.8 49.6 275 16 8 10.3 5.7 12500 11.4 52.5 275 19 10 9.7 5.3 | 11.3 52.3 275 16 8 9.7 5.3 12000 12.7 54.9 275 19 10 9.6 5.3 | 12.7 54.9 270 15 8 9.7 5.3 11750 13.5 56.3 275 18 9 11.0 6.0 | 13.5 56.3 270 15 8 10.7 5.9 11500 14.3 57.7 275 18 9 10.6 5.8 | 14.2 57.6 270 15 8 10.3 5.7 11250 15.1 59.2 275 18 9 10.4 5.7 | 15.0 59.0 270 15 8 9.9 5.4 11000 15.9 60.6 275 18 9 10.3 5.6 | 15.7 60.3 270 14 7 9.6 5.3 10750 16.6 61.9 275 18 9 10.5 5.7 | 16.4 61.5 270 14 7 10.2 5.6 10500 17.4 63.3 275 18 9 10.5 5.8 | 17.2 63.0 270 14 7 10.4 5.7 10250 18.2 64.8 275 17 9 10.6 5.8 | 18.0 64.4 270 14 7 10.1 5.5 10000 19.0 66.2 275 17 9 10.8 5.9 | 18.7 65.7 270 13 7 10.1 5.5 9750 19.8 67.6 275 17 8 10.5 5.8 | 19.5 67.1 265 13 7 9.8 5.4 9500 20.6 69.1 275 16 8 11.5 6.3 | 20.2 68.4 265 12 6 10.7 5.9 9250 21.7 71.1 275 15 8 21.9 12.0 | 21.2 70.2 265 11 6 16.9 9.3 9000 24.4 75.9 275 13 7 59.9 32.9 | 22.8 73.0 265 10 5 31.6 17.3 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