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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000 UXUS97 KPUB 131248 SRGPUB SOARING FORECAST NATIONAL WEATHER SERVICE PUEBLO CO 648 AM MDT THU JUN 13 2013 EXPERIMENTAL PRODUCT This forecast is for Thursday June 13, 2013: If the trigger temperature of 77.0 F/25.0 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1736 ft/min (8.8 m/s) Maximum height of thermals.................. 24780 ft MSL (17119 ft AGL) Forecast maximum temperature................... 89.0 F/32.1 C Time of trigger temperature.................... 1015 MDT 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................. 20557 ft MSL (12896 ft AGL) Thermal soaring outlook for Friday 06/14....... Excellent Wave Soaring Index............................. Poor Wave Soaring Index trend (to 1800 MDT)......... Poor Height of stable layer (12-18K ft MSL)......... None Weak PVA/NVA (through 1800 MDT)................ Weak PVA Potential height of wave....................... 22209 ft MSL (14548 ft AGL) Wave soaring outlook for Friday 06/14.......... Poor Remarks... Sunrise/Sunset.................... 05:33:17 / 20:25:26 MDT Total possible sunshine........... 14 hr 52 min 8 sec (892 min 8 sec) Altitude of sun at 12:59:31 MDT... 74.24 degrees Upper air data from numerical model forecast valid on 06/13/2013 at 0600 MDT Freezing level.................. 16694 ft MSL (9033 ft AGL) Convective condensation level... 20697 ft MSL (13036 ft AGL) Lifted condensation level....... 22122 ft MSL (14462 ft AGL) Lifted index.................... -2.9 K index......................... +10.2 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 -63.7 -82.7 250 27 14 2.4 1.3 77.2 170.9 27.2 M M 45000 -60.1 -76.2 249 28 14 1.9 1.0 59.1 138.4 17.6 M M 40000 -56.3 -69.3 230 36 18 7.6 4.2 43.2 109.8 7.9 M M 38000 -51.6 -60.9 226 35 18 7.8 4.3 41.3 106.3 6.8 M M 36000 -46.9 -52.4 222 35 18 7.7 4.2 40.0 104.0 6.0 M M 34000 -41.9 -43.4 219 34 18 8.5 4.7 38.7 101.6 5.2 M M 32000 -36.8 -34.2 216 34 17 8.6 4.7 37.9 100.2 4.7 M M 30000 -32.2 -26.0 221 29 15 7.5 4.1 36.2 97.1 3.4 M M 29000 -29.9 -21.8 225 26 13 7.5 4.1 35.4 95.7 2.8 M M 28000 -27.1 -16.8 231 24 12 7.5 4.1 34.4 94.0 2.1 M M 27000 -24.9 -12.8 238 24 12 7.5 4.1 33.5 92.2 1.4 M M 26000 -22.6 -8.7 245 25 13 7.5 4.1 32.6 90.7 0.7 M M 25000 -20.4 -4.7 251 27 14 7.3 4.0 31.9 89.4 0.1 M M 24000 -18.2 -0.8 250 29 15 7.2 4.0 30.9 87.6 -0.8 1656 8.4 23000 -16.1 3.0 249 32 17 7.3 4.0 30.0 86.0 -1.6 1562 7.9 22000 -13.9 7.0 248 35 18 8.1 4.5 29.3 84.7 -2.3 1468 7.5 21000 -11.4 11.5 248 33 17 8.5 4.7 28.7 83.7 -2.8 1363 6.9 20000 -8.9 16.0 248 32 17 8.5 4.7 28.3 83.0 -3.2 1257 6.4 19500 -7.6 18.3 248 32 16 8.6 4.7 28.2 82.7 -3.4 1205 6.1 19000 -6.3 20.7 247 30 16 8.7 4.8 28.0 82.4 -3.6 1151 5.8 18500 -5.0 23.0 246 29 15 8.7 4.7 27.8 82.1 -3.8 1097 5.6 18000 -3.7 25.3 245 27 14 9.2 5.0 27.7 81.8 -3.9 1043 5.3 17500 -2.3 27.9 244 26 13 9.3 5.1 27.6 81.6 -4.0 986 5.0 17000 -0.9 30.4 243 25 13 9.3 5.1 27.5 81.5 -4.1 930 4.7 16500 0.4 32.7 243 24 12 9.0 4.9 27.4 81.3 -4.3 874 4.4 16000 1.8 35.2 243 23 12 9.0 4.9 27.3 81.1 -4.4 819 4.2 15500 3.1 37.6 244 22 11 8.8 4.8 27.2 80.9 -4.5 764 3.9 15000 4.4 39.9 246 21 11 8.8 4.8 27.0 80.6 -4.7 710 3.6 14500 5.7 42.3 248 21 11 8.7 4.8 26.9 80.3 -4.9 655 3.3 14000 7.0 44.6 252 21 11 8.6 4.7 26.7 80.0 -5.1 602 3.1 13500 8.3 46.9 256 22 11 8.5 4.6 26.5 79.7 -5.3 548 2.8 13000 9.5 49.1 261 23 12 8.0 4.4 26.2 79.2 -5.6 497 2.5 12500 10.7 51.3 267 24 13 8.0 4.4 26.0 78.7 -5.8 446 2.3 12000 12.0 53.6 269 24 12 8.0 4.4 25.7 78.2 -6.1 395 2.0 11750 12.6 54.7 269 24 12 8.0 4.4 25.6 78.0 -6.3 370 1.9 11500 13.2 55.8 270 23 12 8.0 4.4 25.4 77.8 -6.4 344 1.7 11250 13.8 56.8 270 22 11 8.2 4.5 25.3 77.5 -6.6 319 1.6 11000 14.4 57.9 270 20 10 8.4 4.6 25.2 77.3 -6.7 293 1.5 10750 15.0 59.0 269 18 9 8.2 4.5 25.1 77.1 -6.9 267 1.4 10500 15.6 60.1 268 17 9 8.8 4.8 24.9 76.9 -7.0 242 1.2 10250 16.2 61.2 268 15 8 5.6 3.1 24.8 76.7 -7.2 217 1.1 10000 16.6 61.9 274 13 7 3.5 1.9 23.8 74.9 -8.3 190 1.0 9750 16.8 62.2 277 12 6 4.0 2.2 23.3 74.0 -8.8 177 0.9 9500 16.9 62.4 280 11 6 -0.4 -0.2 22.8 73.1 -9.4 165 0.8 9250 16.6 61.9 276 9 5 -4.2 -2.3 21.8 71.2 -10.5 168 0.9 9000 16.3 61.3 269 7 3 -3.1 -1.7 20.8 69.4 -11.6 170 0.9 8750 15.9 60.6 256 5 2 -3.5 -1.9 19.8 67.7 -12.7 172 0.9 8500 15.6 60.1 241 3 2 -5.6 -3.1 18.8 65.8 -13.8 176 0.9 8250 15.0 59.0 269 3 1 -7.5 -4.1 17.5 63.5 -15.1 184 0.9 8000 14.5 58.1 298 3 2 -6.1 -3.3 16.2 61.2 -16.4 192 1.0 7750 14.0 57.2 318 4 2 -9.9 -5.4 15.0 59.0 -17.7 200 1.0 7500 M M M M M M M M M M M M 7250 M M M M M M M M M M M M 7000 M M M M M M M M M M M M 6750 M M M M M M M M M M M M * * * * * * Numerical weather prediction model forecast data valid * * * * * * 06/13/2013 at 0900 MDT | 06/13/2013 at 1200 MDT | K index... +14.2 | K index... +21.0 | 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 -63.4 -82.1 243 26 13 2.6 1.4 | -63.3 -81.9 230 27 14 2.8 1.5 45000 -59.7 -75.5 238 29 15 2.1 1.1 | -59.3 -74.7 229 33 17 2.0 1.1 40000 -55.9 -68.6 225 38 19 7.4 4.1 | -55.6 -68.1 225 40 21 6.9 3.8 38000 -51.5 -60.7 224 37 19 7.4 4.1 | -51.3 -60.3 224 41 21 7.1 3.9 36000 -46.5 -51.7 223 37 19 7.4 4.1 | -47.1 -52.8 223 42 22 7.1 3.9 34000 -42.0 -43.6 224 34 18 7.4 4.1 | -42.8 -45.0 226 40 21 7.2 3.9 32000 -37.6 -35.7 226 32 16 7.4 4.1 | -38.5 -37.3 230 37 19 7.2 3.9 30000 -33.0 -27.4 229 28 14 7.7 4.2 | -33.8 -28.8 229 34 18 7.9 4.3 29000 -30.7 -23.3 231 26 13 7.7 4.2 | -31.5 -24.7 228 33 17 7.9 4.3 28000 -28.4 -19.1 233 24 12 8.1 4.4 | -28.5 -19.3 227 31 16 8.0 4.4 27000 -26.0 -14.8 235 24 12 8.2 4.5 | -26.1 -15.0 226 31 16 7.9 4.4 26000 -23.5 -10.3 237 25 13 8.2 4.5 | -23.7 -10.7 225 32 16 8.0 4.4 25000 -21.0 -5.8 239 25 13 8.0 4.4 | -21.3 -6.3 224 32 16 7.8 4.3 24000 -18.9 -2.0 238 26 13 7.2 4.0 | -19.0 -2.2 227 32 17 7.8 4.3 23000 -16.2 2.8 237 27 14 7.3 4.0 | -16.7 1.9 230 33 17 7.8 4.3 22000 -14.0 6.8 236 28 15 8.0 4.4 | -14.4 6.1 232 33 17 8.5 4.6 21000 -11.7 10.9 235 29 15 8.1 4.4 | -11.8 10.8 231 33 17 8.7 4.8 20000 -9.3 15.3 235 30 16 8.2 4.5 | -9.3 15.3 230 32 17 8.8 4.8 19500 -8.2 17.2 235 31 16 8.6 4.7 | -8.0 17.6 230 32 16 8.7 4.8 19000 -6.8 19.8 237 30 16 9.1 5.0 | -6.7 19.9 232 30 16 8.6 4.7 18500 -5.5 22.1 239 30 15 9.0 5.0 | -5.5 22.1 234 29 15 8.5 4.7 18000 -4.1 24.6 240 29 15 9.6 5.3 | -4.2 24.4 236 27 14 9.1 5.0 17500 -2.7 27.1 240 27 14 9.6 5.3 | -2.9 26.8 238 25 13 9.1 5.0 17000 -1.3 29.7 240 26 13 9.4 5.2 | -1.5 29.3 240 24 12 9.2 5.1 16500 0.1 32.2 240 24 12 9.2 5.0 | -0.1 31.8 241 23 12 9.5 5.2 16000 1.5 34.7 239 22 11 9.2 5.0 | 1.3 34.3 242 22 11 9.4 5.2 15500 2.9 37.2 239 21 11 9.6 5.2 | 2.7 36.9 243 20 11 9.8 5.4 15000 4.3 39.7 238 20 10 9.6 5.2 | 4.2 39.6 242 19 10 9.8 5.4 14500 5.7 42.3 239 20 10 9.0 4.9 | 5.6 42.1 241 18 9 9.5 5.2 14000 7.0 44.6 240 19 10 8.9 4.9 | 7.0 44.6 241 17 9 9.4 5.1 13500 8.4 47.1 241 19 10 8.8 4.9 | 8.4 47.1 240 16 8 9.4 5.1 13000 9.7 49.5 241 19 10 8.8 4.8 | 9.8 49.6 238 15 8 9.4 5.2 12500 11.0 51.8 241 19 10 8.7 4.8 | 11.2 52.2 236 14 7 9.4 5.1 12000 12.3 54.1 243 19 10 8.6 4.7 | 12.6 54.7 233 13 7 9.2 5.0 11750 13.0 55.4 244 18 9 8.5 4.7 | 13.3 55.9 232 13 7 9.2 5.1 11500 13.6 56.5 245 18 9 8.7 4.7 | 14.0 57.2 230 12 6 9.1 5.0 11250 14.3 57.7 245 18 9 9.0 4.9 | 14.6 58.3 227 12 6 8.6 4.7 11000 14.9 58.8 246 17 9 9.1 5.0 | 15.3 59.5 223 11 6 8.4 4.6 10750 15.6 60.1 246 16 8 9.1 5.0 | 15.9 60.6 219 11 5 8.5 4.6 10500 16.3 61.3 246 16 8 9.0 4.9 | 16.5 61.7 214 10 5 8.5 4.7 10250 16.9 62.4 247 15 8 8.4 4.6 | 17.8 64.0 203 9 5 9.2 5.0 10000 17.5 63.5 249 14 7 8.1 4.4 | 18.4 65.1 196 9 5 9.1 5.0 9750 18.1 64.6 250 14 7 8.4 4.6 | 19.1 66.4 190 9 5 9.2 5.1 9500 19.1 66.4 253 12 6 2.9 1.6 | 19.7 67.5 184 9 5 9.9 5.4 9250 19.1 66.4 252 11 6 0.8 0.4 | 20.5 68.9 180 9 5 10.5 5.8 9000 19.1 66.4 252 11 6 1.0 0.6 | 21.3 70.3 177 10 5 10.0 5.5 8750 19.1 66.4 251 10 5 2.9 1.6 | 22.0 71.6 174 10 5 11.3 6.2 8500 19.4 66.9 248 9 4 8.6 4.7 | 23.0 73.4 171 10 5 16.4 9.0 8250 20.1 68.2 241 6 3 11.1 6.1 | 24.4 75.9 170 10 5 19.4 10.7 8000 20.8 69.4 227 4 2 9.5 5.2 | 25.7 78.3 168 9 5 17.2 9.5 7750 21.5 70.7 197 3 2 14.0 7.7 | 27.1 80.8 167 9 5 23.0 12.6 7500 M M M M M M M | M M M M M M M 7250 M M M M M M M | M M M M M M M 7000 M M M M M M M | M M M M M M M 6750 M M M M M M M | M M M M M M M 06/13/2013 at 1500 MDT | 06/13/2013 at 1800 MDT | K index... +22.4 | K index... +22.1 | 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 -63.4 -82.1 230 28 14 2.8 1.5 | -63.8 -82.8 235 30 15 2.9 1.6 45000 -59.3 -74.7 233 36 19 2.2 1.2 | -59.5 -75.1 237 38 20 2.1 1.1 40000 -55.4 -67.7 236 44 22 6.3 3.5 | -55.7 -68.3 235 42 22 6.7 3.7 38000 -51.5 -60.7 236 43 22 6.5 3.6 | -51.5 -60.7 234 41 21 6.9 3.8 36000 -47.6 -53.7 236 43 22 6.3 3.5 | -47.4 -53.3 234 40 21 6.8 3.7 34000 -42.9 -45.2 234 42 21 8.0 4.4 | -42.6 -44.7 233 38 20 8.2 4.5 32000 -38.2 -36.8 233 40 21 8.0 4.4 | -37.7 -35.9 232 37 19 8.2 4.5 30000 -33.3 -27.9 229 39 20 8.2 4.5 | -32.8 -27.0 232 35 18 8.3 4.5 29000 -30.8 -23.4 227 39 20 8.2 4.5 | -30.3 -22.5 232 34 17 8.3 4.5 28000 -27.8 -18.0 225 38 20 7.7 4.2 | -27.3 -17.1 233 33 17 7.5 4.1 27000 -25.5 -13.9 226 37 19 7.7 4.2 | -25.0 -13.0 236 33 17 7.6 4.2 26000 -23.2 -9.8 228 36 18 7.7 4.3 | -22.7 -8.9 239 33 17 7.6 4.2 25000 -20.9 -5.6 229 34 18 7.8 4.3 | -20.4 -4.7 242 34 17 7.7 4.2 24000 -18.5 -1.3 231 32 17 7.9 4.3 | -18.1 -0.6 242 33 17 7.7 4.2 23000 -16.2 2.8 233 30 16 7.9 4.3 | -15.8 3.6 242 32 16 7.8 4.3 22000 -13.8 7.2 236 28 15 7.7 4.2 | -13.6 7.5 242 31 16 7.5 4.1 21000 -11.6 11.1 237 27 14 7.6 4.2 | -11.4 11.5 241 30 15 7.4 4.0 20000 -9.4 15.1 238 25 13 7.6 4.2 | -9.2 15.4 239 29 15 7.4 4.1 19500 -8.3 17.1 239 25 13 8.0 4.4 | -8.2 17.2 238 28 15 7.7 4.2 19000 -7.0 19.4 238 24 12 9.2 5.0 | -6.9 19.6 235 27 14 9.0 4.9 18500 -5.7 21.7 237 24 12 9.1 5.0 | -5.6 21.9 231 26 14 8.9 4.9 18000 -4.3 24.3 235 23 12 9.6 5.3 | -4.3 24.3 228 26 13 9.7 5.3 17500 -2.8 27.0 235 23 12 9.7 5.3 | -2.8 27.0 227 25 13 9.9 5.4 17000 -1.4 29.5 235 23 12 9.8 5.4 | -1.4 29.5 226 25 13 9.8 5.4 16500 0.1 32.2 234 23 12 9.8 5.4 | 0.1 32.2 225 25 13 9.7 5.3 16000 1.5 34.7 234 23 12 9.8 5.4 | 1.5 34.7 224 24 13 9.7 5.3 15500 3.0 37.4 233 23 12 9.8 5.4 | 3.0 37.4 223 24 12 9.8 5.4 15000 4.5 40.1 233 23 12 9.8 5.4 | 4.4 39.9 223 24 12 9.8 5.4 14500 5.9 42.6 232 23 12 9.7 5.3 | 5.9 42.6 222 24 12 9.6 5.2 14000 7.4 45.3 231 23 12 9.6 5.3 | 7.3 45.1 220 23 12 9.4 5.2 13500 8.8 47.8 230 23 12 9.4 5.2 | 8.7 47.7 218 23 12 9.3 5.1 13000 10.1 50.2 225 23 12 9.1 5.0 | 10.0 50.0 215 22 11 9.1 5.0 12500 11.5 52.7 220 23 12 9.1 5.0 | 11.4 52.5 212 22 11 9.1 5.0 12000 12.8 55.0 215 23 12 8.9 4.9 | 12.7 54.9 206 21 11 8.4 4.6 11750 13.5 56.3 213 23 12 8.9 4.9 | 13.3 55.9 203 21 11 8.4 4.6 11500 14.1 57.4 211 23 12 8.9 4.9 | 13.9 57.0 200 21 11 8.4 4.6 11250 14.8 58.6 208 23 12 8.6 4.7 | 14.5 58.1 197 21 11 8.9 4.9 11000 15.4 59.7 205 23 12 8.4 4.6 | 15.2 59.4 194 21 11 9.4 5.1 10750 16.0 60.8 202 23 12 8.5 4.6 | 15.9 60.6 191 21 11 9.3 5.1 10500 16.6 61.9 198 23 12 8.4 4.6 | 16.5 61.7 188 21 11 9.3 5.1 10250 17.9 64.2 192 23 12 9.4 5.1 | 17.9 64.2 185 21 11 9.6 5.3 10000 18.6 65.5 189 23 12 9.3 5.1 | 18.7 65.7 184 21 11 9.6 5.2 9750 19.3 66.7 186 23 12 9.3 5.1 | 19.4 66.9 182 21 11 9.5 5.2 9500 19.9 67.8 183 23 12 9.5 5.2 | 20.1 68.2 181 20 11 9.7 5.3 9250 20.7 69.3 182 23 12 9.6 5.3 | 20.8 69.4 181 20 10 9.9 5.5 9000 21.4 70.5 182 22 12 9.6 5.2 | 21.6 70.9 180 20 10 10.0 5.5 8750 22.1 71.8 181 22 12 9.6 5.3 | 22.3 72.1 180 20 10 9.8 5.3 8500 22.9 73.2 181 22 11 12.2 6.7 | 23.1 73.6 179 20 10 11.8 6.5 8250 23.9 75.0 179 20 10 14.4 7.9 | 24.0 75.2 177 18 9 14.0 7.7 8000 24.9 76.8 177 18 9 12.8 7.0 | 24.9 76.8 175 16 8 12.4 6.8 7750 25.9 78.6 175 16 8 17.3 9.5 | 25.9 78.6 172 14 7 16.8 9.2 7500 M M M M M M M | M M M M M M M 7250 M M M M M M M | M M M M M M M 7000 M M M M M M M | M M M M M M M 6750 M M M M M M M | M M M M M M M ________________________________________________________________________________ This product is issued one per day 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 numerical weather prediction model data taken near the Air Force Academy in Colorado Springs, Colorado at North Latitude: 38 deg 58 min 48.000 sec West Longitude: 104 deg 49 min 12.000 sec Elevation: 6572 feet (2003 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. At this time, the output from this considered experimental. DEFINITIONS: 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 - 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, cirrostatus, 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. 071806
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