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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 211114
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO CO
514 AM MDT TUE MAY 21 2013
EXPERIMENTAL PRODUCT
This forecast is for Tuesday May 21, 2013:
If the trigger temperature of 47.6 F/8.7 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1039 ft/min (5.3 m/s)
Maximum height of thermals.................. 19555 ft MSL (11893 ft AGL)
Forecast maximum temperature................... 64.0 F/18.2 C
Time of trigger temperature.................... 0800 MDT
Time of overdevelopment........................ 1400 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 16803 ft MSL (9141 ft AGL)
Thermal soaring outlook for Wednesday 05/22.... Excellent
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)................ Weak PVA
Potential height of wave....................... 17501 ft MSL (9839 ft AGL)
Wave soaring outlook for Wednesday 05/22....... Poor
Remarks...
Sunrise/Sunset.................... 05:41:43 / 20:09:55 MDT
Total possible sunshine........... 14 hr 28 min 11 sec (868 min 11 sec)
Altitude of sun at 12:56:01 MDT... 71.33 degrees
Upper air data from numerical model forecast valid on 05/21/2013 at 0600 MDT
Freezing level.................. 10295 ft MSL (2633 ft AGL)
Convective condensation level... 15392 ft MSL (7730 ft AGL)
Lifted condensation level....... 17580 ft MSL (9918 ft AGL)
Lifted index.................... -1.6
K index......................... +8.4
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 -54.9 -66.8 257 10 5 3.3 1.8 94.7 202.4 45.6 M M
45000 -50.1 -58.2 286 17 9 1.4 0.8 80.2 176.3 39.4 M M
40000 -47.7 -53.9 293 17 9 1.5 0.8 60.3 140.5 28.7 M M
38000 -49.0 -56.2 295 15 7 -4.0 -2.2 49.7 121.5 22.2 M M
36000 -51.4 -60.5 296 10 5 -4.0 -2.2 38.0 100.4 14.4 M M
34000 -52.2 -62.0 295 8 4 6.4 3.5 29.1 84.3 8.3 M M
32000 -48.2 -54.8 280 9 5 6.6 3.6 26.4 79.5 6.5 M M
30000 -43.9 -47.0 274 11 6 8.7 4.8 24.5 76.1 5.2 M M
29000 -41.3 -42.3 277 12 6 8.7 4.8 24.0 75.2 4.9 M M
28000 -38.7 -37.7 280 14 7 8.7 4.8 23.7 74.6 4.6 M M
27000 -36.1 -33.0 283 16 8 8.2 4.5 23.4 74.1 4.5 M M
26000 -33.7 -28.7 290 17 9 7.8 4.3 22.6 72.6 3.9 M M
25000 -30.8 -23.4 298 19 10 7.8 4.3 21.7 71.1 3.2 M M
24000 -28.4 -19.1 304 21 11 8.1 4.4 21.1 70.0 2.7 M M
23000 -26.0 -14.8 310 22 11 8.1 4.4 20.4 68.8 2.2 M M
22000 -23.6 -10.5 316 24 12 8.1 4.5 19.9 67.8 1.8 M M
21000 -21.2 -6.2 320 26 13 6.9 3.8 19.2 66.6 1.2 M M
20000 -19.2 -2.6 324 28 14 7.0 3.8 18.2 64.8 0.3 M M
19500 -18.1 -0.6 326 29 15 7.0 3.8 17.8 64.0 -0.1 1031 5.2
19000 -17.1 1.2 328 30 16 7.1 3.9 17.3 63.2 -0.5 985 5.0
18500 -16.1 3.0 329 31 16 6.1 3.3 16.8 62.3 -0.9 941 4.8
18000 -15.2 4.6 329 32 16 6.1 3.3 16.2 61.2 -1.5 900 4.6
17500 -14.3 6.3 330 33 17 6.0 3.3 15.6 60.1 -2.1 859 4.4
17000 -13.5 7.7 330 33 17 6.0 3.3 15.0 58.9 -2.7 818 4.2
16500 -12.6 9.3 330 33 17 6.1 3.3 14.3 57.8 -3.4 777 3.9
16000 -11.8 10.8 330 34 17 5.7 3.1 13.7 56.7 -4.0 737 3.7
15500 -11.0 12.2 330 34 18 5.8 3.2 13.0 55.5 -4.7 698 3.5
15000 -10.1 13.8 331 35 18 5.8 3.2 12.4 54.3 -5.3 658 3.3
14500 -9.3 15.3 331 35 18 5.8 3.2 11.8 53.2 -6.0 618 3.1
14000 -8.4 16.9 331 35 18 6.3 3.4 11.1 52.1 -6.6 577 2.9
13500 -7.4 18.7 331 36 18 6.6 3.6 10.6 51.1 -7.1 533 2.7
13000 -6.5 20.3 331 36 19 7.0 3.8 10.1 50.2 -7.6 489 2.5
12500 -5.3 22.5 331 36 18 7.5 4.1 9.8 49.6 -8.0 441 2.2
12000 -4.2 24.4 331 36 18 7.6 4.2 9.4 49.0 -8.4 392 2.0
11750 -3.7 25.3 331 36 18 7.6 4.2 9.3 48.7 -8.6 368 1.9
11500 -3.1 26.4 331 35 18 7.6 4.2 9.1 48.4 -8.8 343 1.7
11250 -2.5 27.5 331 35 18 7.6 4.2 8.9 48.1 -9.0 319 1.6
11000 -2.0 28.4 331 35 18 7.8 4.3 8.8 47.8 -9.1 295 1.5
10750 -1.4 29.5 331 34 17 8.0 4.4 8.6 47.5 -9.3 270 1.4
10500 -0.8 30.6 331 32 17 8.0 4.4 8.5 47.3 -9.5 245 1.2
10250 -0.2 31.6 331 31 16 8.0 4.4 8.4 47.0 -9.6 219 1.1
10000 0.4 32.7 331 30 15 8.2 4.5 8.2 46.8 -9.8 194 1.0
9750 1.6 34.9 331 27 14 8.4 4.6 8.0 46.4 -10.1 143 0.7
9500 2.3 36.1 331 25 13 8.4 4.6 7.9 46.2 -10.2 117 0.6
9250 2.9 37.2 330 24 12 8.0 4.4 7.8 46.0 -10.4 91 0.5
9000 3.4 38.1 328 22 11 7.1 3.9 7.6 45.7 -10.6 68 0.3
8750 3.9 39.0 325 20 10 8.8 4.8 7.5 45.4 -10.8 44 0.2
8500 4.5 40.1 322 18 9 3.1 1.7 7.3 45.1 -11.0 20 0.1
8250 4.1 39.4 317 15 8 -11.9 -6.5 6.2 43.2 -12.1 24 0.1
8000 2.8 37.0 306 11 5 -19.7 -10.8 4.2 39.6 -14.2 56 0.3
7750 1.5 34.7 283 7 4 -10.9 -6.0 2.2 36.0 -16.3 87 0.4
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 * * * * * *
05/21/2013 at 0900 MDT | 05/21/2013 at 1200 MDT
|
K index... +9.9 | K index... +18.7
|
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 -55.2 -67.4 255 12 6 4.1 2.2 | -55.7 -68.3 257 11 6 3.6 2.0
45000 -49.4 -56.9 273 12 6 1.1 0.6 | -50.5 -58.9 262 14 7 1.3 0.7
40000 -47.6 -53.7 295 16 8 1.2 0.6 | -48.4 -55.1 298 16 8 1.3 0.7
38000 -48.8 -55.8 298 16 8 -3.8 -2.1 | -48.8 -55.8 304 18 9 -1.6 -0.9
36000 -51.1 -60.0 299 13 7 -3.8 -2.1 | -49.8 -57.6 308 19 10 -1.6 -0.9
34000 -51.8 -61.2 297 12 6 6.4 3.5 | -49.7 -57.5 308 19 10 5.1 2.8
32000 -47.8 -54.0 279 12 6 6.7 3.7 | -46.5 -51.7 299 16 8 5.3 2.9
30000 -43.6 -46.5 271 14 7 8.0 4.4 | -43.1 -45.6 292 16 8 6.9 3.8
29000 -41.2 -42.2 276 16 8 8.1 4.4 | -41.0 -41.8 294 18 9 6.9 3.8
28000 -38.7 -37.7 280 19 10 8.1 4.4 | -38.9 -38.0 295 21 11 6.9 3.8
27000 -36.3 -33.3 283 21 11 7.9 4.3 | -36.9 -34.4 296 24 12 7.4 4.1
26000 -34.0 -29.2 289 24 12 7.7 4.2 | -34.5 -30.1 297 26 13 7.9 4.3
25000 -31.1 -24.0 294 28 14 7.7 4.2 | -31.6 -24.9 298 28 15 7.9 4.3
24000 -28.8 -19.8 297 30 16 8.0 4.4 | -29.2 -20.6 298 30 16 8.2 4.5
23000 -26.4 -15.5 295 30 15 8.0 4.4 | -26.7 -16.1 298 31 16 8.2 4.5
22000 -24.0 -11.2 293 29 15 8.0 4.4 | -24.3 -11.7 298 33 17 8.2 4.5
21000 -21.6 -6.9 294 29 15 8.1 4.4 | -21.9 -7.4 299 33 17 7.6 4.2
20000 -19.2 -2.6 301 29 15 8.1 4.5 | -19.6 -3.3 303 34 17 7.7 4.2
19500 -18.0 -0.4 304 29 15 8.2 4.5 | -18.4 -1.1 305 34 17 7.7 4.2
19000 -16.8 1.8 307 30 15 8.3 4.6 | -17.3 0.9 307 34 18 7.9 4.4
18500 -15.7 3.7 311 30 16 6.4 3.5 | -16.3 2.7 308 34 18 5.5 3.0
18000 -14.8 5.4 314 31 16 6.3 3.5 | -15.5 4.1 310 34 18 5.6 3.1
17500 -13.8 7.2 318 32 17 5.8 3.2 | -14.7 5.5 312 35 18 5.9 3.2
17000 -13.1 8.4 320 33 17 4.9 2.7 | -13.8 7.2 312 34 18 6.2 3.4
16500 -12.4 9.7 322 34 18 5.0 2.7 | -12.9 8.8 312 34 17 6.2 3.4
16000 -11.7 10.9 323 35 18 4.7 2.6 | -11.9 10.6 311 32 17 7.6 4.2
15500 -11.0 12.2 324 36 19 4.7 2.6 | -10.8 12.6 309 31 16 7.4 4.1
15000 -10.4 13.3 325 37 19 4.8 2.7 | -9.7 14.5 306 30 15 8.4 4.6
14500 -9.7 14.5 325 37 19 4.9 2.7 | -8.4 16.9 303 28 14 8.5 4.6
14000 -8.9 16.0 326 37 19 5.9 3.3 | -7.2 19.0 299 26 13 8.4 4.6
13500 -7.9 17.8 326 36 19 6.6 3.6 | -6.0 21.2 295 23 12 8.4 4.6
13000 -7.0 19.4 325 36 18 7.1 3.9 | -4.7 23.5 290 21 11 8.5 4.7
12500 -5.9 21.4 325 34 17 7.6 4.1 | -3.5 25.7 289 18 9 8.6 4.7
12000 -4.7 23.5 324 32 16 7.8 4.3 | -2.2 28.0 287 15 7 9.0 4.9
11750 -4.1 24.6 323 30 16 8.1 4.4 | -1.5 29.3 288 13 7 9.7 5.3
11500 -3.5 25.7 323 29 15 8.1 4.4 | -0.8 30.6 291 12 6 9.6 5.3
11250 -3.0 26.6 323 27 14 7.9 4.4 | -0.1 31.8 294 11 6 9.6 5.3
11000 -2.4 27.7 322 26 13 8.5 4.6 | 0.6 33.1 297 10 5 9.8 5.4
10750 -1.7 28.9 323 24 12 9.1 5.0 | 1.4 34.5 300 9 5 10.1 5.6
10500 -1.0 30.2 324 22 11 9.1 5.0 | 2.1 35.8 303 9 4 10.1 5.6
10250 -0.4 31.3 325 20 10 9.0 4.9 | 2.9 37.2 306 8 4 10.1 5.6
10000 1.0 33.8 327 17 9 10.1 5.5 | 3.7 38.7 309 8 4 10.1 5.5
9750 1.8 35.2 328 16 8 10.0 5.5 | 5.1 41.2 313 8 4 10.0 5.5
9500 2.5 36.5 330 14 7 10.0 5.5 | 5.9 42.6 316 8 4 10.0 5.5
9250 3.2 37.8 332 14 7 10.0 5.5 | 6.6 43.9 318 8 4 10.0 5.5
9000 4.0 39.2 333 13 7 10.1 5.6 | 7.4 45.3 321 7 4 10.2 5.6
8750 4.7 40.5 333 13 7 9.6 5.2 | 8.1 46.6 323 7 4 9.7 5.3
8500 5.5 41.9 334 13 7 11.6 6.4 | 8.9 48.0 326 7 4 11.7 6.4
8250 6.5 43.7 335 12 6 16.5 9.1 | 10.0 50.0 329 7 3 19.5 10.7
8000 7.8 46.0 335 11 5 18.4 10.1 | 11.8 53.2 333 6 3 26.5 14.5
7750 9.1 48.4 336 9 5 17.1 9.4 | 13.5 56.3 338 5 3 16.0 8.8
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
05/21/2013 at 1500 MDT | 05/21/2013 at 1800 MDT
|
K index... +20.0 | K index... +21.2
|
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 -56.0 -68.8 263 14 7 3.1 1.7 | -56.6 -69.9 259 14 7 3.1 1.7
45000 -51.6 -60.9 271 21 11 1.2 0.7 | -52.3 -62.1 276 18 10 -0.1 -0.0
40000 -49.7 -57.5 307 19 10 1.2 0.6 | -52.4 -62.3 318 36 18 -0.0 -0.0
38000 -49.8 -57.6 317 24 12 -0.8 -0.5 | -52.0 -61.6 322 44 23 1.0 0.5
36000 -50.3 -58.5 322 30 16 -0.8 -0.5 | -51.4 -60.5 324 53 27 1.0 0.5
34000 -49.5 -57.1 324 33 17 6.5 3.6 | -49.5 -57.1 325 56 29 7.3 4.0
32000 -45.5 -49.9 325 28 14 6.6 3.6 | -45.1 -49.2 325 49 25 7.3 4.0
30000 -41.6 -42.9 324 24 12 6.3 3.5 | -40.7 -41.3 325 42 22 7.7 4.2
29000 -39.7 -39.5 320 24 12 6.3 3.5 | -38.4 -37.1 325 40 21 7.7 4.2
28000 -37.8 -36.0 317 24 13 6.3 3.5 | -36.1 -33.0 326 38 19 7.7 4.2
27000 -35.9 -32.6 314 25 13 6.8 3.8 | -33.8 -28.8 326 36 18 6.9 3.8
26000 -33.2 -27.8 313 26 13 7.2 3.9 | -31.8 -25.2 325 35 18 6.7 3.7
25000 -31.1 -24.0 312 27 14 7.2 4.0 | -29.3 -20.7 323 34 17 6.7 3.7
24000 -28.9 -20.0 312 28 14 7.5 4.1 | -27.3 -17.1 322 33 17 6.5 3.6
23000 -26.7 -16.1 313 30 16 7.5 4.1 | -25.3 -13.5 322 32 17 6.5 3.6
22000 -24.4 -11.9 313 32 17 7.5 4.1 | -23.4 -10.1 322 32 16 6.6 3.6
21000 -22.2 -8.0 314 34 17 7.6 4.2 | -21.4 -6.5 320 31 16 7.1 3.9
20000 -19.9 -3.8 314 33 17 7.6 4.2 | -19.3 -2.7 315 30 16 7.1 3.9
19500 -18.8 -1.8 314 33 17 7.6 4.2 | -18.2 -0.8 313 30 15 7.1 3.9
19000 -17.7 0.1 314 33 17 7.7 4.2 | -17.2 1.0 311 30 15 7.2 3.9
18500 -16.6 2.1 313 32 16 7.4 4.0 | -16.1 3.0 307 29 15 7.6 4.2
18000 -15.5 4.1 311 31 16 7.4 4.1 | -15.0 5.0 303 28 14 7.7 4.2
17500 -14.4 6.1 308 30 15 7.4 4.1 | -13.9 7.0 298 26 14 8.2 4.5
17000 -13.3 8.1 304 28 14 7.5 4.1 | -12.7 9.1 294 25 13 8.6 4.7
16500 -12.2 10.0 299 26 14 7.5 4.1 | -11.5 11.3 289 23 12 8.7 4.8
16000 -11.1 12.0 295 24 12 7.9 4.4 | -10.2 13.6 286 21 11 8.9 4.9
15500 -10.0 14.0 290 21 11 7.9 4.3 | -8.9 16.0 285 19 10 8.9 4.9
15000 -8.7 16.3 285 18 9 9.1 5.0 | -7.6 18.3 284 16 8 8.8 4.8
14500 -7.4 18.7 284 15 8 9.1 5.0 | -6.3 20.7 285 14 7 8.7 4.8
14000 -6.1 21.0 283 12 6 9.6 5.3 | -5.0 23.0 287 11 6 9.6 5.3
13500 -4.6 23.7 285 11 6 9.8 5.4 | -3.5 25.7 287 10 5 9.8 5.4
13000 -3.1 26.4 286 10 5 9.9 5.4 | -2.1 28.2 288 9 5 9.4 5.2
12500 -1.7 28.9 288 10 5 9.9 5.4 | -0.7 30.7 292 7 3 9.1 5.0
12000 -0.2 31.6 290 10 5 9.8 5.4 | 0.6 33.1 299 5 2 9.3 5.1
11750 0.5 32.9 291 9 5 9.7 5.3 | 1.3 34.3 305 4 2 9.6 5.3
11500 1.3 34.3 292 9 5 9.7 5.3 | 2.1 35.8 312 4 2 9.5 5.2
11250 2.0 35.6 293 9 5 9.7 5.3 | 2.8 37.0 322 3 2 9.5 5.2
11000 2.7 36.9 294 9 4 9.8 5.4 | 3.5 38.3 334 3 2 9.6 5.3
10750 3.4 38.1 295 8 4 10.0 5.5 | 4.2 39.6 340 3 2 9.7 5.3
10500 4.2 39.6 296 8 4 9.9 5.5 | 4.9 40.8 345 3 2 9.7 5.3
10250 4.9 40.8 298 8 4 10.0 5.5 | 5.6 42.1 350 3 2 9.7 5.3
10000 6.4 43.5 300 8 4 9.7 5.3 | 6.4 43.5 355 3 2 9.7 5.3
9750 7.1 44.8 302 7 4 9.7 5.3 | 7.8 46.0 004 3 2 9.8 5.4
9500 7.9 46.2 303 7 4 9.7 5.3 | 8.6 47.5 007 3 2 9.8 5.4
9250 8.6 47.5 304 7 4 9.8 5.4 | 9.3 48.7 011 3 2 9.7 5.3
9000 9.3 48.7 306 7 3 10.0 5.5 | 10.0 50.0 014 3 2 9.5 5.2
8750 10.1 50.2 307 6 3 9.8 5.4 | 10.7 51.3 016 4 2 9.5 5.2
8500 10.8 51.4 309 6 3 10.4 5.7 | 11.4 52.5 019 4 2 9.8 5.4
8250 11.7 53.1 312 6 3 13.8 7.6 | 12.2 54.0 023 4 2 11.9 6.5
8000 12.8 55.0 321 5 2 17.6 9.7 | 13.2 55.8 031 3 2 14.5 7.9
7750 14.0 57.2 333 4 2 11.4 6.2 | 14.2 57.6 040 3 2 10.3 5.7
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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