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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 191015
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO CO
415 AM MDT SUN MAY 19 2013
EXPERIMENTAL PRODUCT
This forecast is for Sunday May 19, 2013:
If the trigger temperature of 49.7 F/9.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1302 ft/min (6.6 m/s)
Maximum height of thermals.................. 23151 ft MSL (15488 ft AGL)
Forecast maximum temperature................... 64.0 F/18.2 C
Time of trigger temperature.................... 0745 MDT
Time of overdevelopment........................ 1300 MDT
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 17462 ft MSL (9799 ft AGL)
Thermal soaring outlook for Monday 05/20....... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Same
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 14560 ft MSL (6897 ft AGL)
Wave soaring outlook for Monday 05/20.......... Poor
Remarks...
Sunrise/Sunset.................... 05:43:12 / 20:08:11 MDT
Total possible sunshine........... 14 hr 24 min 59 sec (864 min 59 sec)
Altitude of sun at 12:55:53 MDT... 70.92 degrees
Upper air data from numerical model forecast valid on 05/19/2013 at 0600 MDT
Freezing level.................. 10814 ft MSL (3151 ft AGL)
Convective condensation level... 13187 ft MSL (5524 ft AGL)
Lifted condensation level....... 16093 ft MSL (8430 ft AGL)
Lifted index.................... -6.3
K index......................... +16.6
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 -54.1 -65.4 285 22 11 4.3 2.4 95.5 203.9 46.2 M M
45000 -48.0 -54.4 280 26 14 1.5 0.8 83.3 181.9 41.4 M M
40000 -45.4 -49.7 267 29 15 1.7 0.9 63.6 146.5 31.0 M M
38000 -45.3 -49.5 260 27 14 -0.8 -0.4 55.1 131.2 25.9 M M
36000 -45.8 -50.4 249 23 12 -0.8 -0.4 46.0 114.8 20.1 M M
34000 -46.1 -51.0 236 20 10 0.3 0.2 37.8 100.0 14.6 M M
32000 -46.0 -50.8 230 17 9 0.2 0.1 29.7 85.5 9.0 M M
30000 -45.4 -49.7 222 15 8 7.7 4.2 23.1 73.6 4.1 M M
29000 -43.3 -45.9 219 14 7 6.9 3.8 21.9 71.3 3.2 M M
28000 -41.3 -42.3 217 14 7 6.9 3.8 20.7 69.3 2.3 M M
27000 -39.2 -38.6 214 13 7 6.9 3.8 19.8 67.6 1.6 M M
26000 -36.1 -33.0 220 13 7 8.7 4.8 19.0 66.3 1.0 M M
25000 -33.5 -28.3 225 13 7 8.7 4.8 18.6 65.6 0.7 M M
24000 -30.9 -23.6 231 13 7 8.5 4.7 18.4 65.1 0.4 M M
23000 -28.4 -19.1 238 13 7 8.2 4.5 17.7 63.9 -0.1 1479 7.5
22000 -26.0 -14.8 245 13 7 8.2 4.5 17.2 63.0 -0.6 1376 7.0
21000 -23.6 -10.5 251 13 7 7.9 4.3 16.7 62.1 -1.0 1273 6.5
20000 -21.2 -6.2 260 12 6 7.9 4.3 16.0 60.8 -1.7 1173 6.0
19500 -20.0 -4.0 265 12 6 7.9 4.3 15.7 60.2 -2.0 1123 5.7
19000 -18.9 -2.0 270 12 6 7.9 4.3 15.4 59.7 -2.3 1073 5.5
18500 -17.7 0.1 275 12 6 8.2 4.5 15.1 59.2 -2.5 1023 5.2
18000 -16.4 2.5 274 11 6 8.4 4.6 14.9 58.8 -2.7 971 4.9
17500 -15.2 4.6 274 10 5 8.4 4.6 14.7 58.4 -3.0 918 4.7
17000 -14.1 6.6 273 10 5 6.6 3.6 14.3 57.7 -3.4 871 4.4
16500 -13.1 8.4 273 10 5 6.8 3.7 13.8 56.8 -3.9 826 4.2
16000 -12.1 10.2 273 9 5 7.1 3.9 13.3 55.9 -4.3 781 4.0
15500 -11.0 12.2 278 9 5 7.2 3.9 12.9 55.2 -4.8 735 3.7
15000 -10.0 14.0 283 9 5 7.1 3.9 12.5 54.5 -5.2 689 3.5
14500 -9.0 15.8 288 10 5 6.9 3.8 12.0 53.6 -5.7 644 3.3
14000 -8.0 17.6 293 10 5 7.3 4.0 11.5 52.8 -6.2 600 3.0
13500 -6.8 19.8 293 11 6 8.2 4.5 11.2 52.2 -6.6 550 2.8
13000 -5.6 21.9 292 12 6 8.2 4.5 11.0 51.8 -6.9 499 2.5
12500 -4.4 24.1 290 13 7 8.6 4.7 10.8 51.4 -7.1 447 2.3
12000 -3.2 26.2 288 14 7 8.6 4.7 10.6 51.1 -7.4 395 2.0
11750 -2.5 27.5 287 14 7 8.4 4.6 10.5 50.9 -7.5 369 1.9
11500 -1.9 28.6 287 14 7 8.4 4.6 10.4 50.7 -7.7 344 1.7
11250 -1.3 29.7 287 13 7 8.4 4.6 10.3 50.5 -7.8 318 1.6
11000 -0.7 30.7 288 13 7 8.4 4.6 10.2 50.3 -7.9 293 1.5
10750 -0.1 31.8 289 13 7 8.0 4.4 10.1 50.1 -8.1 267 1.4
10500 0.5 32.9 293 12 6 7.7 4.2 9.9 49.8 -8.3 243 1.2
10250 1.0 33.8 297 11 6 7.7 4.2 9.8 49.6 -8.5 218 1.1
10000 2.2 36.0 306 10 5 8.4 4.6 9.5 49.1 -8.8 169 0.9
9750 2.8 37.0 306 10 5 8.7 4.8 9.4 48.9 -8.9 142 0.7
9500 3.5 38.3 305 9 5 8.6 4.7 9.3 48.7 -9.1 116 0.6
9250 4.1 39.4 305 9 5 8.5 4.6 9.2 48.6 -9.2 89 0.5
9000 4.7 40.5 305 9 5 8.1 4.4 9.1 48.4 -9.3 64 0.3
8750 5.3 41.5 304 9 5 7.8 4.3 9.0 48.1 -9.5 39 0.2
8500 5.8 42.4 304 10 5 8.6 4.7 8.8 47.9 -9.7 14 0.1
8250 6.4 43.5 304 10 5 5.6 3.1 8.7 47.6 -9.8 M M
8000 6.5 43.7 299 8 4 -1.9 -1.1 8.1 46.6 -10.5 M M
7750 6.5 43.7 290 5 3 10.2 5.6 7.4 45.4 -11.3 M M
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 * * * * * *
05/19/2013 at 0900 MDT | 05/19/2013 at 1200 MDT
|
K index... +15.6 | 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 -54.6 -66.3 284 24 13 4.3 2.4 | -55.2 -67.4 283 29 15 4.4 2.4
45000 -48.1 -54.6 279 30 15 2.9 1.6 | -48.5 -55.3 278 33 17 3.2 1.8
40000 -43.8 -46.8 277 33 17 2.9 1.6 | -43.8 -46.8 274 33 17 3.2 1.8
38000 -43.4 -46.1 274 30 15 -0.9 -0.5 | -43.3 -45.9 272 30 15 -0.6 -0.3
36000 -44.0 -47.2 267 26 13 -0.9 -0.5 | -43.6 -46.5 269 26 13 -0.6 -0.3
34000 -44.4 -47.9 257 21 11 -0.3 -0.2 | -43.9 -47.0 264 21 11 -0.1 -0.0
32000 -44.7 -48.5 248 15 8 -0.4 -0.2 | -44.0 -47.2 250 14 7 -0.1 -0.1
30000 -44.5 -48.1 230 11 5 5.4 3.0 | -43.7 -46.7 219 10 5 5.4 3.0
29000 -43.0 -45.4 226 10 5 5.3 2.9 | -42.2 -44.0 201 9 5 5.1 2.8
28000 -41.4 -42.5 222 9 5 5.3 2.9 | -40.2 -40.4 177 9 5 5.1 2.8
27000 -39.4 -38.9 217 8 4 7.1 3.9 | -38.7 -37.7 162 11 6 6.6 3.6
26000 -36.7 -34.1 227 9 5 8.8 4.8 | -36.3 -33.3 170 9 5 8.1 4.4
25000 -34.1 -29.4 236 10 5 8.8 4.8 | -33.9 -29.0 182 7 4 8.1 4.4
24000 -31.5 -24.7 243 11 6 8.7 4.8 | -31.5 -24.7 199 6 3 8.1 4.5
23000 -29.0 -20.2 249 11 5 8.4 4.6 | -29.0 -20.2 219 6 3 8.2 4.5
22000 -26.5 -15.7 255 10 5 8.4 4.6 | -26.6 -15.9 239 6 3 8.2 4.5
21000 -24.0 -11.2 261 10 5 7.7 4.2 | -24.1 -11.4 254 7 4 7.7 4.2
20000 -21.8 -7.2 265 10 5 7.5 4.1 | -21.9 -7.4 261 10 5 7.5 4.1
19500 -20.7 -5.3 267 9 5 7.5 4.1 | -20.8 -5.4 263 11 6 7.5 4.1
19000 -19.5 -3.1 268 9 5 7.6 4.1 | -19.7 -3.5 265 13 7 7.5 4.1
18500 -18.4 -1.1 270 9 5 7.9 4.3 | -18.6 -1.5 266 14 7 7.4 4.1
18000 -17.2 1.0 272 9 5 8.2 4.5 | -17.5 0.5 266 16 8 7.4 4.1
17500 -16.0 3.2 273 10 5 8.2 4.5 | -16.4 2.5 266 17 9 7.4 4.1
17000 -14.8 5.4 275 10 5 7.8 4.3 | -15.4 4.3 267 17 9 6.9 3.8
16500 -13.6 7.5 278 10 5 7.9 4.3 | -14.3 6.3 271 17 9 6.9 3.8
16000 -12.4 9.7 281 10 5 7.5 4.1 | -13.3 8.1 274 17 9 7.3 4.0
15500 -11.3 11.7 285 10 5 7.4 4.1 | -12.2 10.0 279 16 8 7.5 4.1
15000 -10.2 13.6 289 10 5 7.2 3.9 | -11.1 12.0 285 15 7 8.1 4.5
14500 -9.2 15.4 293 10 5 6.8 3.7 | -9.9 14.2 293 12 6 8.8 4.8
14000 -8.2 17.2 297 9 5 6.9 3.8 | -8.6 16.5 303 11 5 9.1 5.0
13500 -7.2 19.0 304 10 5 7.0 3.9 | -7.2 19.0 314 10 5 9.6 5.3
13000 -6.2 20.8 311 10 5 7.1 3.9 | -5.8 21.6 324 10 5 9.7 5.3
12500 -5.1 22.8 315 11 6 7.9 4.3 | -4.3 24.3 330 10 5 10.2 5.6
12000 -3.9 25.0 318 12 6 7.9 4.3 | -2.8 27.0 334 10 5 10.2 5.6
11750 -3.3 26.1 319 13 7 8.7 4.8 | -2.0 28.4 336 10 5 9.9 5.4
11500 -2.7 27.1 318 13 7 9.4 5.2 | -1.3 29.7 337 10 5 9.7 5.3
11250 -2.0 28.4 318 13 7 9.2 5.1 | -0.5 31.1 338 10 5 9.8 5.4
11000 -1.3 29.7 318 13 7 9.3 5.1 | 0.2 32.4 339 10 5 9.8 5.4
10750 -0.6 30.9 318 13 7 9.6 5.3 | 0.9 33.6 339 10 5 9.8 5.4
10500 0.1 32.2 318 12 6 9.8 5.4 | 1.7 35.1 340 11 5 9.9 5.4
10250 1.5 34.7 319 12 6 9.8 5.4 | 3.1 37.6 342 11 5 9.9 5.4
10000 2.3 36.1 319 11 6 10.0 5.5 | 3.9 39.0 342 11 6 10.0 5.5
9750 3.0 37.4 320 11 6 10.1 5.6 | 4.6 40.3 343 11 6 10.1 5.5
9500 3.8 38.8 320 11 5 10.1 5.5 | 5.4 41.7 344 11 6 10.1 5.5
9250 4.5 40.1 320 10 5 10.1 5.6 | 6.2 43.2 345 11 6 10.1 5.6
9000 5.3 41.5 320 10 5 10.0 5.5 | 6.9 44.4 346 11 6 10.1 5.5
8750 6.0 42.8 321 10 5 10.3 5.7 | 7.7 45.9 347 11 6 10.5 5.8
8500 6.8 44.2 321 10 5 9.1 5.0 | 8.4 47.1 348 11 6 8.9 4.9
8250 7.5 45.5 322 10 5 13.7 7.5 | 9.2 48.6 349 11 6 14.8 8.1
8000 8.9 48.0 322 9 5 25.3 13.9 | 10.8 51.4 353 10 5 30.1 16.5
7750 10.5 50.9 322 8 4 7.7 4.2 | 12.7 54.9 360 9 5 9.9 5.5
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
05/19/2013 at 1500 MDT | 05/19/2013 at 1800 MDT
|
K index... +23.0 | K index... +20.7
|
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 -54.2 -65.6 277 26 13 4.3 2.4 | -54.4 -65.9 267 25 13 4.9 2.7
45000 -48.1 -54.6 274 33 17 2.6 1.4 | -47.6 -53.7 263 35 18 2.2 1.2
40000 -44.2 -47.6 269 36 18 2.6 1.4 | -44.3 -47.7 268 38 20 2.2 1.2
38000 -43.6 -46.5 267 34 17 -0.0 -0.0 | -43.9 -47.0 269 37 19 -0.4 -0.2
36000 -43.6 -46.5 265 29 15 -0.0 -0.0 | -44.1 -47.4 268 34 18 -0.4 -0.2
34000 -43.7 -46.7 261 25 13 -0.8 -0.5 | -44.4 -47.9 265 30 16 -0.4 -0.2
32000 -44.2 -47.6 250 20 10 -0.8 -0.4 | -44.6 -48.3 253 24 12 -0.4 -0.2
30000 -44.0 -47.2 234 16 8 6.5 3.6 | -44.1 -47.4 237 19 10 6.4 3.5
29000 -42.2 -44.0 231 15 8 6.0 3.3 | -42.4 -44.3 236 18 9 5.9 3.3
28000 -40.4 -40.7 228 14 7 6.0 3.3 | -40.6 -41.1 235 16 8 5.9 3.3
27000 -38.6 -37.5 224 13 7 6.4 3.5 | -38.8 -37.8 234 15 8 6.5 3.5
26000 -36.2 -33.2 231 12 6 8.3 4.6 | -36.4 -33.5 242 14 7 8.5 4.7
25000 -33.7 -28.7 241 11 6 8.3 4.6 | -33.8 -28.8 251 14 7 8.5 4.7
24000 -31.3 -24.3 252 11 6 8.4 4.6 | -31.3 -24.3 260 15 8 8.6 4.7
23000 -28.4 -19.1 265 12 6 7.7 4.2 | -28.3 -18.9 269 15 8 8.0 4.4
22000 -26.1 -15.0 273 13 7 7.7 4.2 | -25.9 -14.6 276 16 8 8.0 4.4
21000 -23.8 -10.8 279 14 7 7.5 4.1 | -23.6 -10.5 282 17 9 7.3 4.0
20000 -21.6 -6.9 283 15 8 7.5 4.1 | -21.4 -6.5 287 18 9 7.3 4.0
19500 -20.5 -4.9 285 16 8 7.5 4.1 | -20.4 -4.7 289 18 9 7.3 4.0
19000 -19.4 -2.9 287 16 8 7.5 4.1 | -19.3 -2.7 291 18 9 7.3 4.0
18500 -18.3 -0.9 290 17 9 7.1 3.9 | -18.2 -0.8 294 19 10 7.2 3.9
18000 -17.3 0.9 295 16 8 7.0 3.8 | -17.1 1.2 298 18 9 7.1 3.9
17500 -16.3 2.7 302 15 8 7.0 3.8 | -16.1 3.0 302 18 9 7.2 3.9
17000 -15.3 4.5 309 14 7 6.7 3.7 | -15.0 5.0 307 18 9 7.3 4.0
16500 -14.3 6.3 317 13 7 6.7 3.7 | -13.9 7.0 312 18 9 7.3 4.0
16000 -13.3 8.1 325 13 7 7.3 4.0 | -12.9 8.8 317 18 9 7.5 4.1
15500 -12.2 10.0 332 12 6 7.3 4.0 | -11.8 10.8 320 19 10 7.5 4.1
15000 -11.1 12.0 341 12 6 7.9 4.3 | -10.6 12.9 324 19 10 7.5 4.1
14500 -9.9 14.2 348 13 7 8.2 4.5 | -9.5 14.9 326 19 10 7.6 4.2
14000 -8.8 16.2 355 13 7 8.4 4.6 | -8.4 16.9 328 20 10 7.5 4.1
13500 -7.5 18.5 355 13 7 8.8 4.8 | -7.4 18.7 331 18 9 7.4 4.1
13000 -6.2 20.8 355 13 7 8.9 4.9 | -6.3 20.7 334 16 8 7.9 4.3
12500 -4.8 23.4 355 13 7 9.5 5.2 | -5.0 23.0 337 15 8 9.2 5.1
12000 -3.4 25.9 355 13 7 9.6 5.3 | -3.7 25.3 340 14 7 9.3 5.1
11750 -2.7 27.1 355 13 6 10.1 5.6 | -3.0 26.6 341 14 7 9.7 5.3
11500 -1.9 28.6 355 13 6 10.4 5.7 | -2.2 28.0 342 13 7 9.9 5.4
11250 -1.2 29.8 355 12 6 10.3 5.7 | -1.5 29.3 342 13 7 9.9 5.4
11000 -0.4 31.3 355 12 6 10.3 5.7 | -0.8 30.6 343 13 7 9.9 5.4
10750 0.4 32.7 355 12 6 10.4 5.7 | -0.0 32.0 343 13 7 9.8 5.4
10500 1.2 34.2 355 12 6 10.4 5.7 | 0.7 33.3 343 13 7 9.8 5.4
10250 1.9 35.4 355 12 6 10.4 5.7 | 1.4 34.5 344 13 6 9.8 5.4
10000 2.7 36.9 355 12 6 10.3 5.7 | 2.2 36.0 344 13 6 9.9 5.4
9750 3.5 38.3 355 12 6 10.0 5.5 | 3.6 38.5 345 12 6 10.1 5.5
9500 5.0 41.0 356 12 6 9.9 5.5 | 4.4 39.9 346 12 6 10.1 5.6
9250 5.7 42.3 356 12 6 10.0 5.5 | 5.1 41.2 346 12 6 9.9 5.4
9000 6.4 43.5 356 12 6 10.0 5.5 | 5.9 42.6 347 12 6 9.5 5.2
8750 7.2 45.0 356 11 6 10.2 5.6 | 6.6 43.9 347 12 6 9.6 5.3
8500 7.9 46.2 356 11 6 9.3 5.1 | 7.3 45.1 347 12 6 9.1 5.0
8250 8.7 47.7 356 11 6 12.6 6.9 | 8.0 46.4 348 12 6 11.3 6.2
8000 9.9 49.8 004 9 5 20.8 11.4 | 9.0 48.2 352 10 5 16.3 8.9
7750 11.2 52.2 017 7 4 7.2 3.9 | 10.0 50.0 359 9 4 7.3 4.0
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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