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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 221020
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO CO
420 AM MDT WED MAY 22 2013
EXPERIMENTAL PRODUCT
This forecast is for Wednesday May 22, 2013:
If the trigger temperature of 57.9 F/14.4 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1306 ft/min (6.6 m/s)
Maximum height of thermals.................. 21456 ft MSL (13796 ft AGL)
Forecast maximum temperature................... 72.0 F/22.7 C
Time of trigger temperature.................... 0830 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................. 18542 ft MSL (10882 ft AGL)
Thermal soaring outlook for Thursday 05/23..... Fair
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....................... 15272 ft MSL (7612 ft AGL)
Wave soaring outlook for Thursday 05/23........ Poor
Remarks...
Sunrise/Sunset.................... 05:41:01 / 20:10:46 MDT
Total possible sunshine........... 14 hr 29 min 44 sec (869 min 44 sec)
Altitude of sun at 12:56:05 MDT... 71.53 degrees
Upper air data from numerical model forecast valid on 05/22/2013 at 0600 MDT
Freezing level.................. 12549 ft MSL (4889 ft AGL)
Convective condensation level... 15898 ft MSL (8238 ft AGL)
Lifted condensation level....... 18296 ft MSL (10635 ft AGL)
Lifted index.................... -3.5
K index......................... +19.8
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 -57.7 -71.9 249 19 10 2.4 1.3 89.6 193.2 40.0 M M
45000 -54.6 -66.3 261 29 15 -0.9 -0.5 72.5 162.5 31.8 M M
40000 -55.9 -68.6 290 44 22 -0.9 -0.5 48.0 118.4 17.4 M M
38000 -54.9 -66.8 292 43 22 3.0 1.7 40.9 105.5 13.0 M M
36000 -52.9 -63.2 290 37 19 3.0 1.7 34.4 94.0 8.8 M M
34000 -49.9 -57.8 287 34 17 7.8 4.3 30.7 87.2 6.2 M M
32000 -45.2 -49.4 284 33 17 7.8 4.3 29.1 84.3 5.2 M M
30000 -40.4 -40.7 282 32 17 8.3 4.5 27.8 82.0 4.3 M M
29000 -37.9 -36.2 282 31 16 8.3 4.5 27.2 80.9 3.8 M M
28000 -35.5 -31.9 281 30 16 8.3 4.5 26.7 80.0 3.5 M M
27000 -33.0 -27.4 281 29 15 8.2 4.5 26.2 79.1 3.1 M M
26000 -30.6 -23.1 282 29 15 8.2 4.5 25.5 77.9 2.6 M M
25000 -28.1 -18.6 283 28 14 8.2 4.5 25.0 76.9 2.2 M M
24000 -25.7 -14.3 284 27 14 7.7 4.2 24.5 76.1 1.8 M M
23000 -22.9 -9.2 287 27 14 7.6 4.2 23.4 74.1 0.9 M M
22000 -20.6 -5.1 289 27 14 7.6 4.1 22.7 72.8 0.3 M M
21000 -18.5 -1.3 292 27 14 6.5 3.6 21.8 71.2 -0.6 1258 6.4
20000 -16.6 2.1 296 26 14 6.6 3.6 20.6 69.2 -1.6 1171 5.9
19500 -15.7 3.7 299 26 14 6.6 3.6 20.1 68.2 -2.1 1127 5.7
19000 -14.7 5.5 301 26 14 6.6 3.6 19.6 67.3 -2.6 1084 5.5
18500 -13.8 7.2 302 26 13 6.6 3.6 19.1 66.4 -3.1 1040 5.3
18000 -12.8 9.0 303 26 13 6.6 3.6 18.6 65.4 -3.6 997 5.1
17500 -11.8 10.8 303 26 13 7.0 3.9 18.1 64.5 -4.1 953 4.8
17000 -10.8 12.6 303 26 13 7.3 4.0 17.6 63.7 -4.6 907 4.6
16500 -9.7 14.5 302 26 13 7.4 4.1 17.2 63.0 -5.0 860 4.4
16000 -8.6 16.5 301 26 14 8.1 4.4 16.9 62.4 -5.3 811 4.1
15500 -7.4 18.7 299 27 14 8.1 4.4 16.6 61.9 -5.6 760 3.9
15000 -6.2 20.8 298 28 14 7.7 4.2 16.3 61.4 -5.9 711 3.6
14500 -5.1 22.8 297 28 14 7.7 4.2 16.0 60.8 -6.3 662 3.4
14000 -3.9 25.0 296 28 14 8.2 4.5 15.7 60.3 -6.6 612 3.1
13500 -2.7 27.1 296 26 13 8.4 4.6 15.5 59.9 -6.9 560 2.8
13000 -1.4 29.5 296 24 12 8.8 4.8 15.3 59.5 -7.1 508 2.6
12500 -0.1 31.8 296 22 11 9.0 5.0 15.2 59.3 -7.2 453 2.3
12000 1.3 34.3 296 20 10 9.1 5.0 15.1 59.1 -7.4 397 2.0
11750 2.0 35.6 294 19 10 9.2 5.1 15.0 59.0 -7.4 370 1.9
11500 2.7 36.9 291 18 9 9.1 5.0 15.0 58.9 -7.5 342 1.7
11250 3.3 37.9 287 16 8 9.6 5.2 14.9 58.9 -7.6 314 1.6
11000 4.0 39.2 283 15 8 7.9 4.3 14.9 58.8 -7.6 286 1.5
10750 4.5 40.1 280 14 7 5.8 3.2 14.6 58.3 -7.9 265 1.3
10500 4.9 40.8 277 13 6 5.9 3.2 14.3 57.8 -8.2 245 1.2
10250 5.3 41.5 273 11 6 6.1 3.3 14.0 57.3 -8.6 224 1.1
10000 5.8 42.4 268 10 5 5.4 3.0 13.8 56.8 -8.9 204 1.0
9750 6.1 43.0 263 9 5 4.6 2.5 13.4 56.1 -9.3 187 0.9
9500 6.8 44.2 254 8 4 5.1 2.8 12.6 54.7 -10.1 152 0.8
9250 7.1 44.8 248 8 4 2.9 1.6 12.2 54.0 -10.6 135 0.7
9000 7.2 45.0 242 8 4 0.7 0.4 11.6 52.8 -11.3 125 0.6
8750 7.3 45.1 236 8 4 1.7 0.9 10.9 51.6 -11.9 115 0.6
8500 7.3 45.1 230 9 5 0.1 0.1 10.3 50.5 -12.6 106 0.5
8250 7.0 44.6 227 8 4 -8.9 -4.9 9.3 48.7 -13.7 107 0.5
8000 5.9 42.6 231 6 3 -19.5 -10.7 7.4 45.4 -15.5 133 0.7
7750 4.8 40.6 238 4 2 -2.0 -1.1 5.6 42.1 -17.4 158 0.8
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 * * * * * *
05/22/2013 at 0900 MDT | 05/22/2013 at 1200 MDT
|
K index... +18.6 | 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 -58.2 -72.8 249 23 12 2.0 1.1 | -58.5 -73.3 245 25 13 1.3 0.7
45000 -55.6 -68.1 261 37 19 -0.4 -0.2 | -56.7 -70.1 262 40 21 -0.2 -0.1
40000 -56.4 -69.5 287 43 22 -0.5 -0.2 | -57.2 -71.0 280 48 24 -0.2 -0.1
38000 -54.7 -66.5 287 43 22 3.7 2.1 | -55.3 -67.5 282 46 24 3.8 2.1
36000 -52.4 -62.3 284 40 21 3.7 2.1 | -53.1 -63.6 284 43 22 3.8 2.1
34000 -49.2 -56.6 284 38 19 7.8 4.3 | -49.6 -57.3 287 40 21 8.4 4.6
32000 -44.5 -48.1 288 34 18 7.8 4.3 | -44.5 -48.1 293 37 19 8.4 4.6
30000 -40.0 -40.0 291 32 16 7.2 4.0 | -39.4 -38.9 299 35 18 8.7 4.8
29000 -37.8 -36.0 290 32 16 7.2 4.0 | -36.8 -34.2 301 33 17 8.7 4.8
28000 -35.6 -32.1 290 31 16 7.2 4.0 | -34.2 -29.6 303 32 16 8.7 4.8
27000 -33.4 -28.1 289 31 16 8.3 4.6 | -31.7 -25.1 305 31 16 7.3 4.0
26000 -31.0 -23.8 289 31 16 8.2 4.5 | -29.5 -21.1 305 30 16 7.4 4.0
25000 -28.5 -19.3 288 31 16 8.3 4.5 | -27.3 -17.1 306 30 15 7.4 4.1
24000 -25.6 -14.1 287 31 16 7.3 4.0 | -24.7 -12.5 304 29 15 6.3 3.5
23000 -23.4 -10.1 286 31 16 7.4 4.1 | -22.8 -9.0 299 29 15 6.4 3.5
22000 -21.2 -6.2 285 31 16 7.4 4.1 | -21.0 -5.8 295 29 15 6.5 3.6
21000 -19.0 -2.2 285 30 15 7.5 4.1 | -19.0 -2.2 291 29 15 7.1 3.9
20000 -16.7 1.9 287 28 14 7.5 4.1 | -16.9 1.6 289 28 14 7.2 3.9
19500 -15.6 3.9 287 26 14 7.5 4.1 | -15.8 3.6 288 28 14 7.2 3.9
19000 -14.5 5.9 288 25 13 7.5 4.1 | -14.7 5.5 287 28 14 7.3 4.0
18500 -13.5 7.7 292 25 13 6.6 3.6 | -13.7 7.3 287 26 14 7.5 4.1
18000 -12.5 9.5 298 25 13 6.7 3.7 | -12.5 9.5 287 25 13 7.5 4.1
17500 -11.5 11.3 303 26 13 6.6 3.6 | -11.4 11.5 288 24 12 7.8 4.3
17000 -10.6 12.9 309 25 13 6.6 3.6 | -10.3 13.5 289 22 11 7.9 4.3
16500 -9.6 14.7 315 25 13 6.8 3.7 | -9.1 15.6 291 21 11 8.0 4.4
16000 -8.6 16.5 319 24 12 7.3 4.0 | -7.9 17.8 292 19 10 8.3 4.6
15500 -7.5 18.5 323 23 12 7.1 3.9 | -6.7 19.9 294 18 9 8.3 4.6
15000 -6.3 20.7 325 23 12 9.1 5.0 | -5.5 22.1 295 16 8 8.6 4.7
14500 -5.0 23.0 326 23 12 8.9 4.9 | -4.2 24.4 297 14 7 8.6 4.7
14000 -3.7 25.3 325 23 12 9.3 5.1 | -2.9 26.8 298 11 6 9.2 5.0
13500 -2.3 27.9 322 23 12 9.4 5.1 | -1.6 29.1 298 9 5 9.2 5.1
13000 -1.0 30.2 319 23 12 9.0 4.9 | -0.2 31.6 299 7 4 9.4 5.2
12500 0.3 32.5 317 21 11 8.7 4.8 | 1.2 34.2 301 6 3 9.5 5.2
12000 1.6 34.9 315 19 10 8.5 4.7 | 2.6 36.7 302 5 3 9.7 5.3
11750 2.3 36.1 313 18 9 8.3 4.5 | 3.3 37.9 302 5 2 9.9 5.5
11500 2.9 37.2 310 16 8 8.3 4.6 | 4.1 39.4 302 4 2 9.9 5.4
11250 3.5 38.3 306 15 8 8.3 4.5 | 4.8 40.6 302 4 2 9.9 5.5
11000 4.1 39.4 302 14 7 8.4 4.6 | 5.5 41.9 302 4 2 9.7 5.3
10750 4.7 40.5 298 12 6 8.6 4.7 | 6.2 43.2 301 3 2 9.5 5.2
10500 5.4 41.7 292 11 6 8.5 4.7 | 6.9 44.4 300 2 1 9.6 5.2
10250 6.0 42.8 286 10 5 8.7 4.8 | 7.7 45.9 298 2 1 9.5 5.2
10000 6.6 43.9 278 10 5 8.1 4.5 | 8.4 47.1 293 1 1 9.8 5.4
9750 7.8 46.0 273 8 4 7.7 4.2 | 9.9 49.8 000 0 0 10.0 5.5
9500 8.3 46.9 270 7 4 7.7 4.2 | 10.6 51.1 000 0 0 10.1 5.5
9250 8.9 48.0 265 6 3 6.9 3.8 | 11.4 52.5 158 1 0 10.2 5.6
9000 9.3 48.7 259 6 3 6.3 3.5 | 12.1 53.8 147 1 0 10.4 5.7
8750 9.8 49.6 252 6 3 6.2 3.4 | 12.9 55.2 142 1 1 9.9 5.4
8500 10.2 50.4 243 5 3 7.5 4.1 | 13.7 56.7 138 1 1 11.7 6.4
8250 10.9 51.6 236 5 3 13.3 7.3 | 14.7 58.5 132 2 1 18.8 10.3
8000 12.1 53.8 228 4 2 18.6 10.2 | 16.4 61.5 123 2 1 25.2 13.8
7750 13.3 55.9 217 4 2 10.6 5.8 | 18.0 64.4 118 3 2 15.5 8.5
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
05/22/2013 at 1500 MDT | 05/22/2013 at 1800 MDT
|
K index... +24.6 | K index... +25.6
|
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 -58.8 -73.8 252 25 13 1.2 0.6 | -58.9 -74.0 257 24 12 0.9 0.5
45000 -57.3 -71.1 266 38 20 -0.7 -0.4 | -57.8 -72.0 271 36 19 -0.7 -0.4
40000 -58.4 -73.1 277 45 23 -0.6 -0.3 | -58.9 -74.0 273 39 20 -0.6 -0.3
38000 -56.1 -69.0 279 44 22 4.7 2.6 | -56.4 -69.5 272 37 19 5.0 2.7
36000 -53.3 -63.9 280 41 21 4.7 2.6 | -53.5 -64.3 270 34 17 5.0 2.7
34000 -49.4 -56.9 282 38 20 8.5 4.7 | -49.4 -56.9 270 31 16 8.4 4.6
32000 -44.3 -47.7 286 36 18 8.6 4.7 | -44.4 -47.9 273 27 14 8.4 4.6
30000 -39.2 -38.6 289 33 17 8.5 4.7 | -39.3 -38.7 277 25 13 8.6 4.7
29000 -36.7 -34.1 290 33 17 8.5 4.7 | -36.7 -34.1 279 25 13 8.6 4.7
28000 -34.1 -29.4 291 32 16 8.5 4.7 | -34.2 -29.6 280 24 13 8.6 4.7
27000 -31.6 -24.9 294 30 15 8.2 4.5 | -31.6 -24.9 283 23 12 8.5 4.7
26000 -29.2 -20.6 298 27 14 8.2 4.5 | -29.1 -20.4 285 22 11 8.5 4.7
25000 -26.7 -16.1 303 24 13 8.2 4.5 | -26.5 -15.7 288 20 11 8.5 4.7
24000 -24.4 -11.9 307 22 11 7.2 3.9 | -24.1 -11.4 290 19 10 7.3 4.0
23000 -21.7 -7.1 301 21 11 7.2 4.0 | -21.3 -6.3 285 20 10 7.4 4.1
22000 -19.6 -3.3 296 21 11 7.2 4.0 | -19.1 -2.4 282 20 10 7.5 4.1
21000 -17.5 0.5 288 22 11 6.7 3.7 | -17.0 1.4 274 20 11 6.8 3.8
20000 -15.6 3.9 278 24 12 6.7 3.7 | -15.0 5.0 265 22 11 6.9 3.8
19500 -14.6 5.7 274 25 13 6.7 3.7 | -14.0 6.8 261 22 12 7.0 3.9
19000 -13.7 7.3 271 27 14 7.0 3.8 | -13.1 8.4 257 23 12 7.4 4.0
18500 -12.6 9.3 267 25 13 7.7 4.2 | -11.9 10.6 253 22 11 7.9 4.3
18000 -11.5 11.3 263 23 12 7.7 4.2 | -10.8 12.6 249 20 11 7.9 4.3
17500 -10.4 13.3 260 20 10 7.5 4.1 | -9.6 14.7 245 19 10 8.1 4.5
17000 -9.3 15.3 258 17 9 7.5 4.1 | -8.5 16.7 242 18 9 8.2 4.5
16500 -8.2 17.2 256 14 7 7.8 4.3 | -7.3 18.9 238 16 8 8.6 4.7
16000 -7.0 19.4 255 11 6 8.1 4.4 | -5.9 21.4 236 15 8 9.1 5.0
15500 -5.8 21.6 254 8 4 8.1 4.4 | -4.6 23.7 234 14 7 9.2 5.0
15000 -4.5 23.9 251 6 3 9.5 5.2 | -3.2 26.2 231 13 7 9.7 5.3
14500 -3.1 26.4 244 5 2 9.4 5.2 | -1.7 28.9 229 13 6 9.8 5.4
14000 -1.7 28.9 232 4 2 9.1 5.0 | -0.4 31.3 223 12 6 8.2 4.5
13500 -0.4 31.3 220 3 2 9.1 5.0 | 0.8 33.4 212 11 6 8.2 4.5
13000 0.9 33.6 201 3 1 8.6 4.7 | 2.1 35.8 201 11 6 8.0 4.4
12500 2.2 36.0 174 3 2 8.5 4.7 | 3.2 37.8 191 10 5 8.0 4.4
12000 3.4 38.1 156 4 2 8.4 4.6 | 4.4 39.9 180 10 5 8.2 4.5
11750 4.0 39.2 153 5 2 8.4 4.6 | 5.0 41.0 176 10 5 8.4 4.6
11500 4.7 40.5 150 5 3 8.5 4.6 | 5.6 42.1 171 10 5 8.4 4.6
11250 5.3 41.5 149 6 3 8.3 4.5 | 6.3 43.3 166 10 5 8.3 4.6
11000 5.9 42.6 147 7 4 9.1 5.0 | 6.9 44.4 161 10 5 9.0 4.9
10750 6.6 43.9 147 7 4 9.8 5.4 | 7.6 45.7 159 10 5 9.6 5.3
10500 7.3 45.1 146 7 4 9.6 5.3 | 8.3 46.9 157 10 5 9.4 5.2
10250 8.1 46.6 145 7 4 9.6 5.3 | 9.0 48.2 155 10 5 9.4 5.2
10000 8.8 47.8 145 8 4 9.8 5.3 | 9.7 49.5 153 10 5 9.6 5.3
9750 10.3 50.5 144 8 4 9.8 5.4 | 11.2 52.2 152 10 5 9.8 5.4
9500 11.0 51.8 144 8 4 9.9 5.4 | 11.9 53.4 151 10 5 9.8 5.4
9250 11.7 53.1 144 8 4 9.7 5.3 | 12.6 54.7 150 10 5 9.7 5.3
9000 12.4 54.3 144 8 4 9.7 5.3 | 13.3 55.9 150 10 5 9.7 5.3
8750 13.1 55.6 144 8 4 9.5 5.2 | 14.1 57.4 149 10 5 9.6 5.2
8500 13.9 57.0 144 8 4 10.2 5.6 | 14.8 58.6 149 10 5 10.1 5.5
8250 14.7 58.5 143 8 4 14.0 7.7 | 15.6 60.1 147 10 5 12.9 7.1
8000 15.9 60.6 139 9 4 17.8 9.7 | 16.7 62.1 143 9 5 15.9 8.7
7750 17.1 62.8 135 9 5 11.8 6.5 | 17.7 63.9 139 9 5 11.2 6.1
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