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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000 UXUS97 KPUB 151256 SRGPUB SOARING FORECAST NATIONAL WEATHER SERVICE PUEBLO CO 656 AM MDT WED MAY 15 2013 EXPERIMENTAL PRODUCT This forecast is for Wednesday May 15, 2013: If the trigger temperature of 64.2 F/17.9 C is reached...then Thermal Soaring Index....................... Excellent Maximum rate of lift........................ 1040 ft/min (5.3 m/s) Maximum height of thermals.................. 20401 ft MSL (12740 ft AGL) Forecast maximum temperature................... 74.0 F/23.8 C Time of trigger temperature.................... 0845 MDT Time of overdevelopment........................ 1500 MDT Middle/high clouds during soaring window....... Overcast opaque high Surface winds during soaring window............ 20 mph or less Height of the -3 thermal index................. 16229 ft MSL (8568 ft AGL) Thermal soaring outlook for Thursday 05/16..... 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....................... 14563 ft MSL (6902 ft AGL) Wave soaring outlook for Thursday 05/16........ Poor Remarks... Sunrise/Sunset.................... 05:46:29 / 20:04:37 MDT Total possible sunshine........... 14 hr 18 min 7 sec (858 min 7 sec) Altitude of sun at 12:55:44 MDT... 70.04 degrees Upper air data from numerical model forecast valid on 05/15/2013 at 0600 MDT Freezing level.................. 14031 ft MSL (6370 ft AGL) Convective condensation level... 16609 ft MSL (8948 ft AGL) Lifted condensation level....... 17880 ft MSL (10219 ft AGL) Lifted index.................... -3.1 K index......................... +22.7 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 -62.7 -80.9 255 13 7 -0.7 -0.4 82.3 180.1 34.9 M M 45000 -63.5 -82.3 262 7 4 0.8 0.5 57.5 135.6 21.7 M M 40000 -62.3 -80.1 113 4 2 0.7 0.4 37.2 98.9 9.4 M M 38000 -57.8 -72.0 069 4 2 8.1 4.5 34.8 94.6 8.0 M M 36000 -52.9 -63.2 021 5 3 8.1 4.5 33.6 92.4 7.4 M M 34000 -48.0 -54.4 021 7 3 8.5 4.6 32.4 90.3 6.7 M M 32000 -42.9 -45.2 037 7 4 8.5 4.7 31.4 88.5 6.1 M M 30000 -37.8 -36.0 055 8 4 8.4 4.6 30.4 86.7 5.5 M M 29000 -35.3 -31.5 066 8 4 8.4 4.6 29.8 85.7 5.1 M M 28000 -32.8 -27.0 077 8 4 8.4 4.6 29.4 85.0 4.8 M M 27000 -29.7 -21.5 088 9 4 8.0 4.4 28.7 83.6 4.2 M M 26000 -27.3 -17.1 095 9 4 8.1 4.4 28.0 82.4 3.7 M M 25000 -25.0 -13.0 102 9 4 8.1 4.4 27.5 81.4 3.3 M M 24000 -22.7 -8.9 110 8 4 7.2 3.9 26.7 80.0 2.6 M M 23000 -20.6 -5.1 121 6 3 7.2 3.9 25.7 78.3 1.8 M M 22000 -18.4 -1.1 142 4 2 7.2 3.9 24.9 76.7 1.1 M M 21000 -16.2 2.8 155 3 2 7.6 4.2 24.0 75.2 0.4 M M 20000 -13.9 7.0 160 2 1 7.6 4.2 23.3 73.9 -0.3 1199 6.1 19500 -12.8 9.0 164 2 1 7.6 4.2 22.9 73.2 -0.6 1150 5.8 19000 -11.7 10.9 170 2 1 7.5 4.1 22.6 72.7 -0.9 1101 5.6 18500 -10.6 12.9 179 1 0 7.4 4.1 22.2 71.9 -1.3 1055 5.4 18000 -9.6 14.7 329 1 0 7.5 4.1 21.8 71.2 -1.7 1008 5.1 17500 -8.5 16.7 333 1 1 7.7 4.2 21.4 70.6 -2.1 961 4.9 17000 -7.4 18.7 327 2 1 7.7 4.2 21.1 69.9 -2.5 913 4.6 16500 -6.3 20.7 322 2 1 8.3 4.6 20.8 69.4 -2.9 865 4.4 16000 -5.0 23.0 300 2 1 8.7 4.8 20.6 69.0 -3.1 812 4.1 15500 -3.7 25.3 280 3 1 8.6 4.7 20.4 68.8 -3.3 759 3.9 15000 -2.5 27.5 258 2 1 8.1 4.5 20.2 68.3 -3.5 707 3.6 14500 -1.3 29.7 227 2 1 8.2 4.5 19.9 67.8 -3.8 656 3.3 14000 -0.1 31.8 194 2 1 8.1 4.4 19.7 67.4 -4.1 606 3.1 13500 1.1 34.0 150 2 1 8.1 4.4 19.4 66.9 -4.4 555 2.8 13000 2.3 36.1 120 3 2 8.3 4.6 19.1 66.4 -4.7 504 2.6 12500 3.5 38.3 105 5 3 8.3 4.6 18.9 66.0 -4.9 453 2.3 12000 4.8 40.6 098 7 3 9.1 5.0 18.7 65.7 -5.2 400 2.0 11750 5.5 41.9 093 7 4 9.4 5.1 18.7 65.6 -5.2 372 1.9 11500 6.2 43.2 089 8 4 9.3 5.1 18.7 65.6 -5.3 343 1.7 11250 6.9 44.4 086 8 4 9.3 5.1 18.6 65.5 -5.3 315 1.6 11000 7.6 45.7 083 9 4 9.6 5.3 18.6 65.5 -5.3 287 1.5 10750 8.3 46.9 082 9 5 9.7 5.3 18.6 65.5 -5.4 257 1.3 10500 9.0 48.2 081 9 5 9.7 5.3 18.6 65.5 -5.4 228 1.2 10250 9.8 49.6 080 9 5 9.7 5.3 18.6 65.5 -5.4 199 1.0 10000 11.1 52.0 081 9 5 8.6 4.7 18.5 65.3 -5.5 143 0.7 9750 11.8 53.2 082 8 4 8.8 4.8 18.4 65.1 -5.6 116 0.6 9500 12.4 54.3 084 8 4 8.5 4.7 18.3 65.0 -5.7 89 0.5 9250 13.0 55.4 082 7 4 8.1 4.4 18.2 64.8 -5.8 63 0.3 9000 13.6 56.5 072 5 3 7.0 3.8 18.1 64.5 -6.0 39 0.2 8750 14.2 57.6 055 4 2 9.9 5.4 17.9 64.2 -6.2 15 0.1 8500 14.8 58.6 029 4 2 -0.8 -0.4 17.7 63.9 -6.3 M M 8250 13.7 56.7 346 3 1 -23.8 -13.0 16.0 60.8 -8.1 14 0.1 8000 11.5 52.7 296 4 2 -29.6 -16.3 13.1 55.6 -11.1 73 0.4 7750 9.3 48.7 276 6 3 -28.6 -15.7 10.3 50.5 -14.1 132 0.7 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 * * * * * * 05/15/2013 at 0900 MDT | 05/15/2013 at 1200 MDT | K index... +23.6 | K index... +22.6 | 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 -62.9 -81.2 264 15 8 -0.8 -0.4 | -62.5 -80.5 273 16 8 -0.7 -0.4 45000 -63.8 -82.8 283 7 3 1.0 0.5 | -63.3 -81.9 265 7 4 0.6 0.3 40000 -62.3 -80.1 000 0 0 1.2 0.7 | -62.4 -80.3 260 5 3 0.7 0.4 38000 -57.8 -72.0 352 3 2 8.2 4.5 | -57.9 -72.2 292 6 3 8.3 4.5 36000 -52.9 -63.2 349 7 4 8.2 4.5 | -52.9 -63.2 311 9 4 8.3 4.5 34000 -47.8 -54.0 359 7 4 8.6 4.7 | -47.9 -54.2 313 8 4 8.6 4.7 32000 -42.7 -44.9 027 6 3 8.6 4.7 | -42.7 -44.9 302 4 2 8.6 4.7 30000 -37.6 -35.7 061 5 3 8.2 4.5 | -37.5 -35.5 258 3 1 8.6 4.7 29000 -35.2 -31.4 081 6 3 8.2 4.5 | -34.3 -29.7 228 3 2 8.6 4.7 28000 -32.1 -25.8 101 7 3 8.2 4.5 | -31.7 -25.1 214 4 2 8.7 4.8 27000 -29.7 -21.5 108 6 3 8.0 4.4 | -29.3 -20.7 218 4 2 7.9 4.3 26000 -27.3 -17.1 115 6 3 8.1 4.4 | -27.0 -16.6 227 4 2 7.9 4.3 25000 -25.0 -13.0 122 6 3 8.1 4.4 | -24.6 -12.3 237 4 2 7.9 4.4 24000 -22.7 -8.9 127 5 2 7.2 3.9 | -22.4 -8.3 245 3 2 7.4 4.0 23000 -20.6 -5.1 133 3 1 7.2 3.9 | -20.2 -4.4 254 2 1 7.4 4.0 22000 -18.4 -1.1 163 1 0 7.2 3.9 | -18.0 -0.4 276 1 1 7.4 4.1 21000 -16.2 2.8 000 0 0 7.5 4.1 | -15.9 3.4 000 0 0 7.0 3.9 20000 -14.0 6.8 068 1 1 7.5 4.1 | -13.8 7.2 114 3 1 7.1 3.9 19500 -12.9 8.8 064 2 1 7.5 4.1 | -12.8 9.0 114 4 2 7.1 3.9 19000 -11.8 10.8 061 2 1 7.3 4.0 | -11.7 10.9 114 5 3 7.0 3.9 18500 -10.7 12.7 054 3 1 7.3 4.0 | -10.7 12.7 112 6 3 7.0 3.9 18000 -9.7 14.5 048 3 2 7.3 4.0 | -9.6 14.7 111 6 3 7.0 3.9 17500 -8.6 16.5 045 4 2 7.5 4.1 | -8.6 16.5 110 7 4 7.1 3.9 17000 -7.6 18.3 044 5 3 7.5 4.1 | -7.5 18.5 108 8 4 7.1 3.9 16500 -6.4 20.5 042 6 3 8.6 4.7 | -6.5 20.3 106 9 5 7.0 3.9 16000 -5.1 22.8 034 6 3 9.0 4.9 | -5.5 22.1 103 8 4 7.0 3.8 15500 -3.8 25.2 027 6 3 8.9 4.9 | -4.5 23.9 098 6 3 7.3 4.0 15000 -2.5 27.5 024 5 3 8.5 4.7 | -3.3 26.1 090 6 3 8.3 4.5 14500 -1.3 29.7 022 5 3 8.5 4.7 | -2.2 28.0 080 5 3 8.2 4.5 14000 -0.0 32.0 028 5 3 8.4 4.6 | -0.8 30.6 074 5 3 10.0 5.5 13500 1.2 34.2 040 5 2 8.4 4.6 | 0.6 33.1 072 5 3 9.9 5.4 13000 2.5 36.5 055 5 2 8.2 4.5 | 2.1 35.8 072 5 3 9.9 5.4 12500 3.7 38.7 073 5 3 8.2 4.5 | 3.6 38.5 071 5 3 9.9 5.5 12000 4.9 40.8 082 6 3 8.5 4.7 | 5.1 41.2 071 5 3 9.7 5.3 11750 5.5 41.9 080 6 3 8.6 4.7 | 5.8 42.4 070 5 3 9.6 5.3 11500 6.2 43.2 079 6 3 8.5 4.7 | 6.5 43.7 069 5 3 9.7 5.3 11250 6.8 44.2 077 7 4 8.7 4.8 | 7.2 45.0 068 5 3 9.7 5.3 11000 7.5 45.5 076 7 4 9.0 5.0 | 8.0 46.4 068 5 3 9.7 5.3 10750 8.1 46.6 073 8 4 9.2 5.1 | 8.7 47.7 067 5 3 9.8 5.4 10500 8.8 47.8 071 8 4 9.2 5.0 | 9.4 48.9 067 5 3 9.7 5.3 10250 10.2 50.4 067 9 4 9.2 5.1 | 10.9 51.6 065 5 3 10.1 5.6 10000 10.9 51.6 064 9 4 9.3 5.1 | 11.7 53.1 065 5 3 10.3 5.6 9750 11.6 52.9 061 9 4 9.3 5.1 | 12.4 54.3 065 5 3 10.3 5.6 9500 12.3 54.1 059 9 5 9.3 5.1 | 13.2 55.8 065 5 3 10.1 5.6 9250 13.0 55.4 055 8 4 9.1 5.0 | 13.9 57.0 064 5 3 9.7 5.3 9000 13.6 56.5 049 7 4 9.3 5.1 | 14.6 58.3 063 5 3 9.7 5.3 8750 14.3 57.7 041 6 3 8.6 4.7 | 15.4 59.7 062 5 3 9.1 5.0 8500 14.9 58.8 031 6 3 11.2 6.2 | 16.1 61.0 061 5 3 11.7 6.4 8250 15.9 60.6 027 5 3 15.4 8.4 | 17.1 62.8 061 6 3 16.1 8.8 8000 17.0 62.6 026 4 2 14.4 7.9 | 18.3 64.9 062 6 3 15.6 8.5 7750 18.1 64.6 025 4 2 18.5 10.2 | 19.4 66.9 062 6 3 18.9 10.4 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 05/15/2013 at 1500 MDT | 05/15/2013 at 1800 MDT | K index... +24.9 | K index... +25.1 | 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 -62.1 -79.8 265 18 9 -0.1 -0.0 | -63.1 -81.6 279 21 11 -0.3 -0.2 45000 -62.3 -80.1 262 16 8 -0.1 -0.1 | -63.4 -82.1 270 20 10 0.4 0.2 40000 -62.5 -80.5 259 10 5 -1.2 -0.7 | -62.8 -81.0 246 18 9 0.8 0.4 38000 -58.1 -72.6 271 10 5 8.5 4.6 | -58.0 -72.4 249 16 8 8.7 4.8 36000 -52.4 -62.3 284 12 6 8.5 4.6 | -52.8 -63.0 255 15 8 8.7 4.8 34000 -47.2 -53.0 280 12 6 8.7 4.8 | -47.5 -53.5 257 16 8 8.7 4.8 32000 -42.0 -43.6 269 11 6 8.8 4.8 | -42.3 -44.1 257 17 9 8.8 4.8 30000 -36.8 -34.2 264 11 6 8.7 4.8 | -37.0 -34.6 255 16 8 8.9 4.9 29000 -34.3 -29.7 263 11 6 8.7 4.8 | -34.4 -29.9 254 15 8 8.9 4.9 28000 -31.7 -25.1 262 10 5 8.7 4.8 | -31.0 -23.8 252 13 7 9.0 4.9 27000 -29.3 -20.7 267 10 5 7.8 4.3 | -28.6 -19.5 250 11 6 7.9 4.3 26000 -26.9 -16.4 275 9 5 7.8 4.3 | -26.3 -15.3 248 10 5 7.9 4.4 25000 -24.6 -12.3 285 8 4 7.8 4.3 | -23.9 -11.0 245 9 4 8.0 4.4 24000 -22.4 -8.3 290 7 4 7.1 3.9 | -21.7 -7.1 235 8 4 6.8 3.7 23000 -19.8 -3.6 280 5 2 7.1 3.9 | -19.7 -3.5 223 9 5 6.8 3.7 22000 -17.7 0.1 261 3 1 7.2 3.9 | -17.8 -0.0 213 10 5 6.8 3.7 21000 -15.7 3.7 189 4 2 6.6 3.6 | -15.9 3.4 201 12 6 6.3 3.4 20000 -13.8 7.2 167 8 4 6.7 3.7 | -14.0 6.8 191 15 8 6.3 3.4 19500 -12.8 9.0 162 10 5 6.7 3.7 | -13.1 8.4 187 17 9 6.3 3.5 19000 -11.8 10.8 160 12 6 7.0 3.8 | -12.2 10.0 184 19 10 6.9 3.8 18500 -10.8 12.6 159 13 7 7.1 3.9 | -11.1 12.0 183 19 10 7.5 4.1 18000 -9.7 14.5 158 14 7 7.2 3.9 | -10.0 14.0 181 19 10 7.4 4.1 17500 -8.6 16.5 159 15 8 7.6 4.1 | -8.8 16.2 180 18 9 8.6 4.7 17000 -7.5 18.5 160 14 7 7.5 4.1 | -7.5 18.5 180 16 8 8.5 4.7 16500 -6.4 20.5 161 13 7 7.8 4.3 | -6.3 20.7 179 15 8 8.3 4.6 16000 -5.3 22.5 158 11 6 7.8 4.3 | -5.1 22.8 176 13 7 8.2 4.5 15500 -4.2 24.4 154 9 4 8.0 4.4 | -3.9 25.0 173 11 5 8.3 4.5 15000 -3.0 26.6 146 7 4 8.4 4.6 | -2.7 27.1 170 9 5 8.4 4.6 14500 -1.7 28.9 132 5 3 8.5 4.6 | -1.4 29.5 167 7 4 8.3 4.5 14000 -0.4 31.3 122 5 2 10.0 5.5 | -0.1 31.8 164 6 3 9.7 5.3 13500 1.1 34.0 117 4 2 9.9 5.4 | 1.3 34.3 163 6 3 9.6 5.3 13000 2.5 36.5 112 4 2 9.6 5.3 | 2.7 36.9 161 5 3 9.5 5.2 12500 3.9 39.0 107 4 2 9.6 5.3 | 4.2 39.6 155 3 2 9.5 5.2 12000 5.4 41.7 102 4 2 9.8 5.4 | 5.6 42.1 141 2 1 9.4 5.2 11750 6.1 43.0 099 4 2 9.8 5.4 | 6.3 43.3 130 2 1 9.4 5.2 11500 6.9 44.4 097 3 2 9.8 5.4 | 7.0 44.6 115 2 1 9.4 5.2 11250 7.6 45.7 094 3 2 9.9 5.4 | 7.7 45.9 096 2 1 9.4 5.2 11000 8.3 46.9 090 3 2 10.0 5.5 | 8.4 47.1 076 2 1 9.6 5.3 10750 9.1 48.4 087 3 2 10.0 5.5 | 9.1 48.4 057 2 1 9.7 5.3 10500 9.8 49.6 083 3 2 10.0 5.5 | 9.8 49.6 044 2 1 9.7 5.3 10250 10.5 50.9 079 3 2 10.0 5.5 | 11.3 52.3 030 3 2 9.7 5.3 10000 11.3 52.3 075 3 2 9.9 5.4 | 12.0 53.6 026 4 2 9.8 5.4 9750 12.0 53.6 071 3 2 9.9 5.4 | 12.7 54.9 024 4 2 9.8 5.4 9500 13.5 56.3 063 3 2 9.9 5.4 | 13.4 56.1 021 5 3 9.7 5.3 9250 14.2 57.6 060 3 2 9.8 5.4 | 14.2 57.6 020 5 3 9.6 5.3 9000 15.0 59.0 058 3 2 9.9 5.4 | 14.9 58.8 020 5 3 9.6 5.3 8750 15.7 60.3 055 3 2 9.5 5.2 | 15.6 60.1 020 6 3 9.6 5.2 8500 16.4 61.5 053 3 2 10.9 6.0 | 16.3 61.3 020 6 3 9.9 5.4 8250 17.3 63.1 055 3 2 13.7 7.5 | 17.0 62.6 022 6 3 10.6 5.8 8000 18.3 64.9 059 4 2 14.0 7.7 | 17.7 63.9 027 5 3 10.9 6.0 7750 19.3 66.7 062 4 2 14.9 8.2 | 18.5 65.3 033 5 2 10.8 5.9 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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- Page last modified: May 1st, 2013 15:32 UTC