Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
438 UXUS97 KPUB 151207 SRGPUB Soaring Forecast National Weather Service Pueblo, Colorado 0607 MDT Sunday, September 15, 2024 This forecast is for Villa Grove, CO for Sunday, September 15, 2024: If the trigger temperature of 65.6 F/18.7 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1195 ft/min (6.1 m/s) Maximum height of thermals.................. 20923 ft MSL (11973 ft AGL) Forecast maximum temperature................... 75.0 F/24.3 C Time of trigger temperature.................... 1000 MDT Time of overdevelopment........................ 1600 MDT Middle/high clouds during soaring window....... None Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 18128 ft MSL (9178 ft AGL) Thermal soaring outlook for Monday 09/16....... Excellent Wave Soaring Index............................. Not available Remarks... Sunrise/Sunset.................... 06:46:02 / 19:11:02 MDT Total possible sunshine........... 12 hr 25 min 0 sec (745 min 0 sec) Altitude of sun at 12:58:32 MDT... 54.34 degrees Upper air data from numerical model forecast valid on 09/15/2024 at 0600 MDT Freezing level.................. 15492 ft MSL (6542 ft AGL) Convective condensation level... 20699 ft MSL (11749 ft AGL) Lifted condensation level....... 20974 ft MSL (12024 ft AGL) Lifted index.................... -1.4 K index......................... +8.3 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 -60.4 -76.7 250 38 20 1.7 1.0 M M M M M 45000 -57.4 -71.3 250 52 27 2.3 1.3 M M M M M 40000 -53.7 -64.7 250 42 21 4.3 2.3 M M M M M 38000 -51.3 -60.3 245 35 18 4.1 2.2 M M M M M 36000 -48.9 -56.0 235 28 15 4.2 2.3 M M M M M 34000 -44.4 -47.9 230 24 13 8.6 4.7 M M M M M 32000 -39.3 -38.7 225 21 11 8.6 4.7 M M M M M 30000 -33.8 -28.8 215 19 10 7.8 4.3 29.7 85.4 4.5 M M 29000 -31.5 -24.7 205 19 10 7.8 4.3 29.0 84.2 4.1 M M 28000 -29.1 -20.4 200 19 10 8.4 4.6 28.4 83.1 3.6 M M 27000 -26.5 -15.7 195 18 10 8.9 4.9 28.0 82.3 3.3 M M 26000 -23.8 -10.8 185 18 9 8.9 4.9 27.6 81.7 3.1 M M 25000 -21.2 -6.2 180 17 9 8.9 4.9 27.4 81.3 2.9 M M 24000 -18.7 -1.7 185 17 9 7.9 4.3 26.7 80.1 2.4 M M 23000 -16.4 2.5 190 17 9 7.9 4.3 26.1 78.9 1.9 M M 22000 -14.0 6.8 200 17 9 7.6 4.2 25.5 77.9 1.4 M M 21000 -12.3 9.9 210 17 9 5.5 3.0 24.1 75.4 0.1 M M 20000 -10.7 12.7 215 18 9 5.5 3.0 22.7 72.8 -1.2 1125 5.7 19500 -9.9 14.2 220 18 9 5.4 3.0 22.0 71.6 -1.8 1086 5.5 19000 -8.9 16.0 225 19 10 7.6 4.2 21.5 70.6 -2.3 1043 5.3 18500 -7.8 18.0 225 20 10 7.8 4.3 21.1 70.0 -2.7 995 5.1 18000 -6.7 19.9 230 21 11 8.0 4.4 20.8 69.5 -3.0 946 4.8 17500 -5.5 22.1 230 21 11 8.4 4.6 20.6 69.0 -3.3 895 4.5 17000 -4.3 24.3 230 21 11 8.3 4.6 20.3 68.6 -3.6 844 4.3 16500 -3.0 26.6 230 21 11 9.2 5.0 20.2 68.3 -3.8 791 4.0 16000 -1.7 28.9 230 21 11 9.2 5.1 20.1 68.1 -4.0 736 3.7 15500 -0.3 31.5 230 21 11 9.2 5.0 20.0 68.0 -4.1 680 3.5 15000 1.1 34.0 230 21 11 9.1 5.0 19.9 67.8 -4.2 625 3.2 14500 2.4 36.3 230 20 10 8.2 4.5 19.8 67.6 -4.3 569 2.9 14000 3.7 38.7 235 19 10 9.8 5.4 19.6 67.3 -4.5 516 2.6 13500 5.8 42.4 235 18 9 7.0 3.8 19.5 67.2 -4.7 431 2.2 13000 7.0 44.6 235 17 9 10.4 5.7 19.2 66.6 -5.0 381 1.9 12500 8.4 47.1 240 16 8 9.1 5.0 19.3 66.7 -5.0 323 1.6 12000 9.5 49.1 240 14 7 8.5 4.7 18.9 66.1 -5.4 274 1.4 11750 10.3 50.5 240 13 7 10.3 5.6 18.9 66.1 -5.4 245 1.2 11500 11.0 51.8 245 12 6 8.9 4.9 18.9 66.1 -5.4 216 1.1 11250 11.6 52.9 245 11 6 7.2 4.0 18.8 65.8 -5.6 191 1.0 11000 12.1 53.8 245 10 5 6.3 3.5 18.6 65.4 -5.8 169 0.9 10750 12.6 54.7 245 9 5 8.6 4.7 18.3 65.0 -6.1 146 0.7 10500 13.2 55.8 245 8 4 7.4 4.1 18.3 64.9 -6.1 119 0.6 10250 13.5 56.3 245 8 4 1.8 1.0 17.9 64.2 -6.6 102 0.5 10000 13.6 56.5 250 7 4 -0.7 -0.4 17.2 62.9 -7.3 95 0.5 9750 13.6 56.5 250 7 4 3.7 2.1 16.5 61.6 -8.1 87 0.4 9500 13.8 56.8 255 7 3 -5.1 -2.8 15.9 60.7 -8.6 74 0.4 9250 12.2 54.0 255 5 3 -37.6 -20.6 13.6 56.5 -10.9 113 0.6 9000 9.4 48.9 260 4 2 -19.9 -10.9 10.1 50.1 -14.5 191 1.0 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 * * * * * * 09/15/2024 at 0900 MDT | 09/15/2024 at 1200 MDT | CAPE... +1.2 LI... -1.5 | CAPE... +287.5 LI... -0.7 CINH... -40.8 K Index... +24.1 | CINH... -7.3 K Index... +17.3 | 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 -59.9 -75.8 255 34 18 2.0 1.1 | -59.7 -75.5 255 36 18 2.7 1.5 45000 -56.8 -70.2 255 46 24 1.9 1.0 | -55.7 -68.3 255 47 24 2.0 1.1 40000 -53.8 -64.8 245 44 23 4.0 2.2 | -52.7 -62.9 245 56 29 2.8 1.5 38000 -51.5 -60.7 235 37 19 3.8 2.1 | -51.0 -59.8 235 46 23 2.8 1.5 36000 -49.2 -56.6 220 32 17 3.9 2.2 | -49.4 -56.9 225 37 19 2.9 1.6 34000 -44.9 -48.8 215 30 15 8.5 4.7 | -45.4 -49.7 215 33 17 8.4 4.6 32000 -39.8 -39.6 210 29 15 8.5 4.7 | -40.3 -40.5 215 31 16 8.4 4.6 30000 -34.2 -29.6 200 27 14 8.2 4.5 | -34.7 -30.5 210 29 15 8.4 4.6 29000 -31.8 -25.2 195 27 14 8.2 4.5 | -32.1 -25.8 205 28 15 8.4 4.6 28000 -29.3 -20.7 190 27 14 8.3 4.6 | -29.6 -21.3 205 28 14 8.1 4.4 27000 -26.8 -16.2 185 26 14 8.5 4.6 | -27.3 -17.1 200 28 14 7.6 4.2 26000 -24.3 -11.7 180 26 14 8.5 4.6 | -25.1 -13.2 200 27 14 7.6 4.2 25000 -21.7 -7.1 180 26 14 8.6 4.7 | -22.8 -9.0 195 27 14 7.7 4.2 24000 -19.7 -3.5 180 24 12 6.4 3.5 | -20.8 -5.4 195 25 13 6.7 3.7 23000 -17.8 -0.0 185 22 11 6.4 3.5 | -18.8 -1.8 190 22 12 6.7 3.7 22000 -15.9 3.4 195 19 10 6.5 3.5 | -16.8 1.8 185 20 10 6.9 3.8 21000 -13.8 7.2 200 17 9 7.1 3.9 | -14.5 5.9 185 19 10 8.0 4.4 20000 -11.8 10.8 210 14 7 7.3 4.0 | -12.1 10.2 185 19 10 8.0 4.4 19500 -10.8 12.6 215 13 7 7.3 4.0 | -10.9 12.4 185 19 10 8.0 4.4 19000 -9.7 14.5 220 13 7 8.8 4.8 | -9.7 14.5 185 19 10 9.0 4.9 18500 -8.4 16.9 215 13 7 8.8 4.8 | -8.3 17.1 185 19 10 9.0 5.0 18000 -7.0 19.4 215 14 7 8.6 4.7 | -7.0 19.4 185 18 9 9.0 4.9 17500 -5.9 21.4 215 15 7 8.1 4.4 | -5.7 21.7 185 18 9 8.8 4.8 17000 -4.7 23.5 215 15 8 8.0 4.4 | -4.4 24.1 185 18 9 8.8 4.9 16500 -3.5 25.7 210 16 8 8.9 4.9 | -3.1 26.4 190 18 9 9.1 5.0 16000 -2.2 28.0 215 16 8 8.9 4.9 | -1.8 28.8 190 18 9 9.1 5.0 15500 -0.9 30.4 215 16 8 9.3 5.1 | -0.5 31.1 190 19 10 9.3 5.1 15000 0.5 32.9 215 16 8 9.5 5.2 | 1.0 33.8 195 18 10 9.5 5.2 14500 2.5 36.5 215 15 8 8.4 4.6 | 2.4 36.3 195 18 9 8.9 4.9 14000 4.0 39.2 220 15 8 9.6 5.3 | 4.4 39.9 195 18 9 9.5 5.2 13500 5.4 41.7 220 15 7 8.4 4.6 | 5.8 42.4 195 18 9 6.7 3.7 13000 6.7 44.1 225 14 7 10.1 5.6 | 7.0 44.6 195 17 9 10.4 5.7 12500 8.2 46.8 225 14 7 9.1 5.0 | 8.4 47.1 195 16 8 8.8 4.8 12000 9.5 49.1 225 13 7 7.9 4.3 | 9.5 49.1 195 15 8 8.2 4.5 11750 10.1 50.2 225 13 6 8.1 4.4 | 10.2 50.4 195 14 7 9.8 5.4 11500 10.7 51.3 225 12 6 7.4 4.0 | 10.9 51.6 195 13 6 8.9 4.9 11250 11.2 52.2 225 11 6 6.2 3.4 | 11.5 52.7 195 12 6 8.3 4.5 11000 11.7 53.1 220 10 5 5.7 3.1 | 12.1 53.8 195 11 6 7.7 4.3 10750 12.2 54.0 220 9 4 6.9 3.8 | 12.7 54.9 200 11 6 10.8 5.9 10500 12.7 54.9 220 8 4 5.9 3.2 | 13.6 56.5 200 11 6 12.5 6.8 10250 13.0 55.4 220 8 4 2.5 1.4 | 14.5 58.1 200 10 5 10.3 5.7 10000 13.1 55.6 220 8 4 2.1 1.2 | 15.2 59.4 200 10 5 10.4 5.7 9750 13.3 55.9 220 8 4 1.2 0.7 | 16.0 60.8 200 10 5 9.5 5.2 9500 13.3 55.9 220 8 4 3.3 1.8 | 16.8 62.2 200 10 5 14.7 8.1 9250 13.8 56.8 225 6 3 11.6 6.4 | 18.4 65.1 200 9 5 28.3 15.5 9000 14.5 58.1 235 4 2 4.9 2.7 | 20.3 68.5 200 8 4 17.5 9.6 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 09/15/2024 at 1500 MDT | 09/15/2024 at 1800 MDT | CAPE... +303.4 LI... -0.9 | CAPE... +106.3 LI... -1.1 CINH... -1.3 K Index... +18.7 | CINH... -84.9 K Index... +19.9 | 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 -60.1 -76.2 260 42 21 2.9 1.6 | -60.6 -77.1 265 42 22 2.8 1.6 45000 -55.8 -68.4 265 56 29 2.2 1.2 | -56.0 -68.8 270 54 28 3.7 2.0 40000 -52.4 -62.3 260 59 30 4.2 2.3 | -50.5 -58.9 265 53 27 4.3 2.4 38000 -50.0 -58.0 250 53 27 4.0 2.2 | -47.9 -54.2 265 44 23 4.2 2.3 36000 -47.6 -53.7 240 49 25 4.0 2.2 | -45.4 -49.7 265 36 18 4.3 2.3 34000 -43.9 -47.0 230 41 21 7.0 3.9 | -42.0 -43.6 260 25 13 6.2 3.4 32000 -39.7 -39.5 220 32 16 7.0 3.9 | -37.8 -36.0 235 15 8 6.1 3.4 30000 -34.6 -30.3 220 26 14 7.9 4.3 | -33.7 -28.7 225 15 8 7.1 3.9 29000 -32.2 -26.0 220 25 13 7.9 4.4 | -31.6 -24.9 220 16 8 7.1 3.9 28000 -29.8 -21.6 225 24 12 7.9 4.3 | -29.5 -21.1 220 18 9 7.2 4.0 27000 -27.5 -17.5 220 23 12 7.8 4.3 | -27.2 -17.0 225 19 10 7.7 4.2 26000 -25.2 -13.4 215 21 11 7.9 4.3 | -24.8 -12.6 225 21 11 7.7 4.2 25000 -22.8 -9.0 210 20 11 8.0 4.4 | -22.5 -8.5 225 23 12 7.7 4.2 24000 -20.7 -5.3 205 19 10 6.8 3.7 | -20.2 -4.4 225 22 11 7.6 4.2 23000 -18.7 -1.7 190 19 10 6.8 3.7 | -18.0 -0.4 225 21 11 7.6 4.2 22000 -16.7 1.9 180 20 10 6.9 3.8 | -15.7 3.7 225 19 10 7.7 4.2 21000 -14.3 6.3 175 21 11 8.1 4.4 | -13.6 7.5 225 21 11 7.1 3.9 20000 -11.9 10.6 175 22 11 8.1 4.4 | -11.5 11.3 225 24 12 7.2 4.0 19500 -10.7 12.7 175 23 12 8.1 4.4 | -10.5 13.1 225 25 13 7.2 4.0 19000 -9.5 14.9 175 23 12 8.4 4.6 | -9.4 15.1 225 26 13 8.1 4.4 18500 -8.3 17.1 180 21 11 8.4 4.6 | -8.2 17.2 230 26 14 8.3 4.6 18000 -7.0 19.4 180 20 10 8.6 4.7 | -7.0 19.4 230 27 14 8.4 4.6 17500 -5.7 21.7 180 19 10 9.3 5.1 | -5.7 21.7 235 27 14 9.0 5.0 17000 -4.4 24.1 180 18 9 9.3 5.1 | -4.4 24.1 235 27 14 9.0 5.0 16500 -3.0 26.6 185 17 9 9.2 5.1 | -3.1 26.4 235 26 13 9.2 5.1 16000 -1.6 29.1 185 17 9 9.2 5.1 | -1.7 28.9 235 25 13 9.3 5.1 15500 -0.3 31.5 185 16 8 9.4 5.1 | -0.4 31.3 235 25 13 9.2 5.0 15000 1.1 34.0 185 16 8 9.6 5.2 | 1.6 34.9 230 23 12 9.2 5.0 14500 2.5 36.5 185 16 8 10.1 5.5 | 2.8 37.0 230 23 12 7.5 4.1 14000 4.7 40.5 185 16 8 9.4 5.2 | 3.9 39.0 225 22 11 7.6 4.2 13500 6.1 43.0 185 15 8 7.8 4.3 | 5.0 41.0 220 21 11 7.0 3.8 13000 7.4 45.3 190 15 8 11.1 6.1 | 6.0 42.8 215 19 10 7.2 4.0 12500 9.0 48.2 190 15 8 9.8 5.4 | 7.1 44.8 210 18 9 7.0 3.8 12000 10.2 50.4 190 15 8 9.9 5.4 | 8.0 46.4 205 15 8 6.7 3.7 11750 11.1 52.0 190 15 8 12.2 6.7 | 8.6 47.5 200 14 7 7.7 4.2 11500 12.0 53.6 190 15 8 10.9 6.0 | 9.1 48.4 200 13 7 7.2 4.0 11250 12.7 54.9 190 14 7 9.1 5.0 | 9.7 49.5 200 12 6 6.3 3.4 11000 13.4 56.1 190 14 7 8.2 4.5 | 10.1 50.2 195 10 5 5.4 3.0 10750 14.0 57.2 190 14 7 10.8 5.9 | 10.5 50.9 195 8 4 7.2 3.9 10500 14.9 58.8 190 14 7 12.1 6.6 | 11.1 52.0 190 6 3 8.7 4.8 10250 15.8 60.4 190 14 7 10.2 5.6 | 11.7 53.1 185 5 3 8.8 4.8 10000 16.5 61.7 190 14 7 9.7 5.3 | 12.4 54.3 180 4 2 9.2 5.1 9750 17.2 63.0 190 13 7 9.7 5.3 | 13.0 55.4 165 3 1 9.0 4.9 9500 18.0 64.4 190 13 7 13.7 7.5 | 13.7 56.7 145 2 1 10.6 5.8 9250 19.4 66.9 190 12 6 23.4 12.8 | 14.7 58.5 130 2 1 14.5 8.0 9000 21.2 70.2 185 10 5 22.5 12.3 | 15.8 60.4 105 2 1 14.9 8.2 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