Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 171135
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO CO
534 AM MDT FRI MAY 17 2013
EXPERIMENTAL PRODUCT
This forecast is for Friday May 17, 2013:
If the trigger temperature of 66.3 F/19.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1835 ft/min (9.3 m/s)
Maximum height of thermals.................. 26183 ft MSL (18523 ft AGL)
Forecast maximum temperature................... 83.0 F/28.8 C
Time of trigger temperature.................... 0815 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................. 21367 ft MSL (13707 ft AGL)
Thermal soaring outlook for Saturday 05/18..... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 35772 ft MSL (28112 ft AGL)
Wave soaring outlook for Saturday 05/18........ Poor
Remarks...
Sunrise/Sunset.................... 05:44:47 / 20:06:25 MDT
Total possible sunshine........... 14 hr 21 min 37 sec (861 min 37 sec)
Altitude of sun at 12:55:47 MDT... 70.49 degrees
Upper air data from numerical model forecast valid on 05/17/2013 at 0600 MDT
Freezing level.................. 14202 ft MSL (6542 ft AGL)
Convective condensation level... 18048 ft MSL (10388 ft AGL)
Lifted condensation level....... 21186 ft MSL (13526 ft AGL)
Lifted index.................... -4.3
K index......................... +18.0
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 -61.2 -78.2 248 25 13 -1.0 -0.5 84.5 184.2 33.3 M M
45000 -62.4 -80.3 255 31 16 0.7 0.4 59.0 138.3 19.5 M M
40000 -61.3 -78.3 248 25 13 0.5 0.3 38.4 101.2 6.9 M M
38000 -57.0 -70.6 247 26 14 8.0 4.4 36.0 96.7 5.3 M M
36000 -52.1 -61.8 246 28 15 8.0 4.4 34.6 94.4 4.5 M M
34000 -47.2 -53.0 246 29 15 8.2 4.5 33.3 92.0 3.7 M M
32000 -42.3 -44.1 246 28 15 8.2 4.5 32.1 89.8 2.8 M M
30000 -37.4 -35.3 247 27 14 8.2 4.5 30.9 87.6 2.0 M M
29000 -35.0 -31.0 248 26 13 8.2 4.5 30.3 86.5 1.5 M M
28000 -31.9 -25.4 250 25 13 8.2 4.5 29.6 85.3 1.0 M M
27000 -29.5 -21.1 251 25 13 7.8 4.3 28.9 84.0 0.4 M M
26000 -27.2 -17.0 252 25 13 7.8 4.3 28.2 82.7 -0.2 1807 9.2
25000 -24.8 -12.6 254 24 13 7.8 4.3 27.5 81.5 -0.7 1707 8.7
24000 -22.5 -8.5 254 24 12 7.7 4.2 26.8 80.3 -1.3 1607 8.2
23000 -20.1 -4.2 254 24 12 7.7 4.2 26.1 78.9 -2.0 1508 7.7
22000 -17.8 -0.0 254 24 12 7.8 4.3 25.4 77.7 -2.5 1409 7.2
21000 -15.8 3.6 252 22 11 6.4 3.5 24.4 75.9 -3.5 1318 6.7
20000 -13.9 7.0 248 20 10 6.4 3.5 23.2 73.8 -4.6 1232 6.3
19500 -12.9 8.8 245 19 10 6.5 3.5 22.7 72.8 -5.1 1189 6.0
19000 -12.0 10.4 242 19 10 6.2 3.4 22.2 71.9 -5.6 1146 5.8
18500 -11.2 11.8 236 17 9 5.7 3.1 21.5 70.7 -6.3 1107 5.6
18000 -10.4 13.3 229 16 8 5.6 3.0 20.8 69.5 -7.1 1069 5.4
17500 -9.4 15.1 224 15 8 9.4 5.1 20.4 68.8 -7.5 1023 5.2
17000 -8.0 17.6 223 15 8 9.3 5.1 20.3 68.6 -7.7 967 4.9
16500 -6.6 20.1 222 15 8 9.3 5.1 20.3 68.5 -7.8 910 4.6
16000 -5.2 22.6 223 15 8 9.4 5.1 20.2 68.4 -7.9 853 4.3
15500 -3.8 25.2 223 15 8 9.4 5.1 20.1 68.3 -8.0 796 4.0
15000 -2.4 27.7 225 15 8 9.2 5.1 20.1 68.1 -8.1 740 3.8
14500 -1.0 30.2 226 15 8 9.3 5.1 20.0 68.0 -8.2 683 3.5
14000 0.4 32.7 228 15 8 9.2 5.1 19.9 67.8 -8.3 627 3.2
13500 1.7 35.1 230 15 8 9.2 5.1 19.8 67.7 -8.4 571 2.9
13000 3.1 37.6 232 15 8 9.4 5.2 19.8 67.6 -8.6 514 2.6
12500 4.6 40.3 235 15 8 9.5 5.2 19.7 67.5 -8.6 456 2.3
12000 6.0 42.8 238 15 8 9.2 5.1 19.7 67.4 -8.7 399 2.0
11750 6.7 44.1 239 15 8 9.1 5.0 19.6 67.3 -8.8 371 1.9
11500 7.3 45.1 240 15 8 9.1 5.0 19.6 67.2 -8.9 344 1.7
11250 8.0 46.4 241 15 8 9.1 5.0 19.5 67.1 -9.0 316 1.6
11000 8.7 47.7 241 15 8 8.9 4.9 19.5 67.0 -9.0 288 1.5
10750 9.3 48.7 240 14 7 8.8 4.8 19.4 66.9 -9.2 261 1.3
10500 10.0 50.0 238 13 7 8.8 4.8 19.3 66.8 -9.3 235 1.2
10250 10.6 51.1 236 13 7 8.8 4.8 19.2 66.6 -9.4 208 1.1
10000 11.9 53.4 230 11 6 8.0 4.4 19.0 66.3 -9.7 156 0.8
9750 12.4 54.3 226 11 5 8.1 4.4 18.9 66.0 -9.8 131 0.7
9500 13.0 55.4 221 10 5 8.0 4.4 18.8 65.8 -10.0 107 0.5
9250 13.6 56.5 218 9 5 7.2 4.0 18.6 65.5 -10.2 82 0.4
9000 14.0 57.2 220 10 5 6.1 3.3 18.4 65.1 -10.5 61 0.3
8750 14.5 58.1 223 10 5 8.2 4.5 18.1 64.7 -10.8 40 0.2
8500 15.0 59.0 225 10 5 1.1 0.6 17.9 64.2 -11.1 19 0.1
8250 14.2 57.6 229 10 5 -22.7 -12.5 16.4 61.5 -12.7 35 0.2
8000 11.6 52.9 234 8 4 -40.5 -22.2 13.2 55.7 -16.0 105 0.5
7750 9.0 48.2 245 6 3 -15.2 -8.3 9.9 49.9 -19.3 175 0.9
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 * * * * * *
05/17/2013 at 0900 MDT | 05/17/2013 at 1200 MDT
|
K index... +0.7 | K index... -0.4
|
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 -61.3 -78.3 249 26 13 -0.9 -0.5 | -61.5 -78.7 240 24 13 -1.4 -0.7
45000 -62.3 -80.1 243 28 15 0.9 0.5 | -63.0 -81.4 231 35 18 1.2 0.7
40000 -60.9 -77.6 228 28 14 0.4 0.2 | -61.1 -78.0 231 34 18 0.7 0.4
38000 -56.9 -70.4 229 26 14 7.5 4.1 | -57.1 -70.8 230 34 17 7.6 4.2
36000 -52.4 -62.3 231 25 13 7.5 4.1 | -52.0 -61.6 230 33 17 7.6 4.2
34000 -47.8 -54.0 233 24 13 8.0 4.4 | -47.3 -53.1 230 31 16 8.0 4.4
32000 -42.9 -45.2 235 24 12 8.0 4.4 | -42.5 -44.5 230 30 15 8.0 4.4
30000 -38.0 -36.4 236 24 12 8.3 4.5 | -37.7 -35.9 233 29 15 7.9 4.4
29000 -34.9 -30.8 236 25 13 8.3 4.5 | -35.4 -31.7 236 28 15 7.9 4.4
28000 -32.5 -26.5 236 26 13 8.3 4.6 | -33.0 -27.4 238 28 15 7.9 4.4
27000 -30.1 -22.2 237 26 14 7.6 4.2 | -30.6 -23.1 238 28 15 7.7 4.2
26000 -27.8 -18.0 239 27 14 7.6 4.2 | -28.3 -18.9 235 29 15 7.7 4.2
25000 -25.6 -14.1 241 27 14 7.6 4.2 | -26.0 -14.8 233 29 15 7.7 4.2
24000 -23.1 -9.6 243 27 14 8.5 4.6 | -23.7 -10.7 232 29 15 8.0 4.4
23000 -20.6 -5.1 246 27 14 8.5 4.7 | -20.7 -5.3 231 27 14 8.0 4.4
22000 -18.0 -0.4 248 26 13 8.5 4.7 | -18.3 -0.9 230 25 13 8.0 4.4
21000 -15.5 4.1 246 25 13 8.5 4.6 | -15.9 3.4 230 24 13 7.9 4.3
20000 -13.0 8.6 240 24 13 8.4 4.6 | -13.6 7.5 232 24 12 7.9 4.3
19500 -11.7 10.9 237 24 12 8.4 4.6 | -12.4 9.7 233 24 12 7.9 4.3
19000 -10.4 13.3 234 24 12 7.1 3.9 | -11.2 11.8 234 24 12 8.2 4.5
18500 -9.6 14.7 231 23 12 5.6 3.1 | -10.0 14.0 235 24 12 8.3 4.6
18000 -8.8 16.2 227 23 12 5.4 3.0 | -8.7 16.3 237 23 12 8.4 4.6
17500 -7.9 17.8 225 22 11 6.5 3.6 | -7.6 18.3 239 22 11 7.0 3.8
17000 -7.0 19.4 226 20 10 6.6 3.6 | -6.6 20.1 240 21 11 7.2 3.9
16500 -6.0 21.2 227 18 9 7.2 3.9 | -5.5 22.1 241 19 10 7.4 4.0
16000 -4.9 23.2 225 17 8 7.7 4.2 | -4.5 23.9 239 16 8 7.6 4.2
15500 -3.8 25.2 223 15 8 8.0 4.4 | -3.4 25.9 235 13 7 8.3 4.5
15000 -2.5 27.5 221 14 7 9.4 5.1 | -2.1 28.2 232 11 6 9.4 5.2
14500 -1.1 30.0 219 13 7 9.3 5.1 | -0.7 30.7 229 10 5 9.4 5.2
14000 0.2 32.4 219 13 6 9.0 4.9 | 0.7 33.3 226 9 5 9.6 5.3
13500 1.5 34.7 222 12 6 9.0 5.0 | 2.1 35.8 226 9 5 9.6 5.3
13000 2.9 37.2 226 12 6 8.5 4.6 | 3.5 38.3 224 9 5 10.0 5.5
12500 4.1 39.4 234 12 6 8.4 4.6 | 5.0 41.0 222 9 4 10.0 5.5
12000 5.4 41.7 241 13 7 8.8 4.8 | 6.5 43.7 220 8 4 9.9 5.4
11750 6.0 42.8 244 13 7 9.0 4.9 | 7.2 45.0 220 8 4 9.9 5.4
11500 6.7 44.1 246 13 7 9.0 4.9 | 8.0 46.4 219 8 4 9.9 5.4
11250 7.4 45.3 249 13 7 9.0 4.9 | 8.7 47.7 219 8 4 9.9 5.4
11000 8.1 46.6 251 13 7 9.2 5.0 | 9.4 48.9 218 8 4 9.9 5.4
10750 8.7 47.7 252 13 7 9.3 5.1 | 10.2 50.4 217 8 4 9.9 5.5
10500 10.1 50.2 253 13 7 9.3 5.1 | 10.9 51.6 216 8 4 9.9 5.5
10250 10.8 51.4 254 13 7 9.3 5.1 | 11.7 53.1 215 8 4 9.9 5.5
10000 11.5 52.7 253 12 6 9.3 5.1 | 12.4 54.3 214 8 4 9.9 5.4
9750 12.2 54.0 253 12 6 9.4 5.1 | 13.1 55.6 213 7 4 9.9 5.4
9500 12.9 55.2 252 12 6 9.2 5.1 | 14.6 58.3 210 7 4 9.9 5.4
9250 13.5 56.3 252 12 6 8.2 4.5 | 15.4 59.7 209 7 4 10.0 5.5
9000 14.1 57.4 253 12 6 7.8 4.3 | 16.1 61.0 208 7 4 10.2 5.6
8750 14.6 58.3 253 12 6 7.5 4.1 | 16.8 62.2 207 7 4 9.4 5.2
8500 15.1 59.2 254 12 6 9.4 5.1 | 17.6 63.7 206 7 3 12.2 6.7
8250 16.0 60.8 253 11 6 13.8 7.6 | 18.7 65.7 204 6 3 19.2 10.5
8000 17.0 62.6 252 9 5 15.5 8.5 | 20.3 68.5 201 6 3 22.3 12.2
7750 18.1 64.6 250 7 4 14.3 7.9 | 21.8 71.2 197 5 3 19.5 10.7
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
05/17/2013 at 1500 MDT | 05/17/2013 at 1800 MDT
|
K index... +13.6 | K index... +12.1
|
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 -61.3 -78.3 253 26 13 -1.4 -0.7 | -59.9 -75.8 265 25 13 -0.5 -0.3
45000 -62.9 -81.2 245 38 19 0.8 0.5 | -60.6 -77.1 261 35 18 -0.5 -0.3
40000 -61.6 -78.9 235 42 22 0.4 0.2 | -61.4 -78.5 234 38 20 -1.0 -0.5
38000 -57.7 -71.9 238 42 21 7.7 4.2 | -57.2 -71.0 232 39 20 7.6 4.1
36000 -52.4 -62.3 242 41 21 7.7 4.2 | -52.7 -62.9 232 39 20 7.6 4.1
34000 -47.6 -53.7 243 39 20 8.4 4.6 | -47.9 -54.2 233 39 20 8.2 4.5
32000 -42.6 -44.7 242 37 19 8.4 4.6 | -43.0 -45.4 234 39 20 8.2 4.5
30000 -37.6 -35.7 237 35 18 8.3 4.5 | -38.0 -36.4 235 37 19 8.7 4.8
29000 -35.1 -31.2 233 35 18 8.3 4.6 | -35.3 -31.5 236 36 19 8.7 4.8
28000 -32.6 -26.7 230 35 18 8.3 4.6 | -32.7 -26.9 236 35 18 8.7 4.8
27000 -30.2 -22.4 227 35 18 7.7 4.2 | -30.2 -22.4 237 34 18 8.0 4.4
26000 -27.9 -18.2 224 35 18 7.7 4.2 | -27.8 -18.0 238 33 17 8.0 4.4
25000 -25.6 -14.1 222 35 18 7.7 4.2 | -25.4 -13.7 240 32 17 7.9 4.4
24000 -23.4 -10.1 221 35 18 6.7 3.7 | -22.7 -8.9 241 31 16 6.7 3.7
23000 -20.8 -5.4 225 32 17 6.8 3.7 | -20.7 -5.3 243 30 15 6.7 3.7
22000 -18.8 -1.8 228 31 16 6.7 3.7 | -18.7 -1.7 245 29 15 6.6 3.6
21000 -16.5 2.3 232 28 14 8.2 4.5 | -16.4 2.5 245 26 13 8.1 4.4
20000 -14.1 6.6 237 24 12 8.3 4.5 | -14.0 6.8 244 23 12 8.2 4.5
19500 -12.9 8.8 240 23 12 8.3 4.6 | -12.8 9.0 243 22 11 8.3 4.5
19000 -11.6 11.1 243 21 11 8.9 4.9 | -11.6 11.1 242 20 11 8.9 4.9
18500 -10.3 13.5 244 19 10 9.2 5.1 | -10.3 13.5 241 21 11 9.2 5.1
18000 -8.9 16.0 245 17 9 9.3 5.1 | -8.9 16.0 240 21 11 9.3 5.1
17500 -7.6 18.3 246 16 8 9.1 5.0 | -7.6 18.3 239 21 11 9.1 5.0
17000 -6.2 20.8 245 15 8 9.1 5.0 | -6.2 20.8 237 21 11 9.1 5.0
16500 -4.9 23.2 245 14 7 9.5 5.2 | -4.9 23.2 236 22 11 9.3 5.1
16000 -3.4 25.9 243 13 7 9.6 5.3 | -3.5 25.7 235 22 11 9.4 5.2
15500 -2.0 28.4 241 13 6 9.5 5.2 | -2.1 28.2 233 22 11 9.5 5.2
15000 -0.6 30.9 236 12 6 9.3 5.1 | -0.6 30.9 232 22 11 9.9 5.4
14500 0.7 33.3 230 11 6 9.2 5.1 | 0.9 33.6 231 22 12 9.9 5.4
14000 2.1 35.8 223 11 6 9.6 5.3 | 2.3 36.1 229 22 12 9.6 5.3
13500 3.6 38.5 217 11 6 9.6 5.3 | 3.8 38.8 228 23 12 9.7 5.3
13000 5.0 41.0 211 11 6 9.8 5.4 | 5.2 41.4 226 23 12 9.6 5.2
12500 6.5 43.7 206 11 6 9.8 5.4 | 6.6 43.9 224 23 12 9.6 5.2
12000 7.9 46.2 201 12 6 9.8 5.4 | 8.1 46.6 222 23 12 9.9 5.4
11750 8.6 47.5 198 12 6 9.7 5.3 | 8.8 47.8 221 23 12 10.0 5.5
11500 9.4 48.9 196 12 6 9.8 5.4 | 9.5 49.1 220 23 12 10.0 5.5
11250 10.1 50.2 193 12 6 9.8 5.4 | 10.3 50.5 219 23 12 10.0 5.5
11000 10.8 51.4 191 13 6 9.9 5.4 | 11.0 51.8 217 23 12 9.7 5.3
10750 11.6 52.9 190 13 7 10.0 5.5 | 11.7 53.1 216 22 12 9.5 5.2
10500 12.3 54.1 189 13 7 10.0 5.5 | 12.4 54.3 214 22 11 9.5 5.2
10250 13.0 55.4 188 13 7 10.0 5.5 | 13.1 55.6 212 22 11 9.5 5.2
10000 13.8 56.8 186 13 7 10.0 5.5 | 13.9 57.0 211 22 11 9.7 5.3
9750 15.3 59.5 184 13 7 10.1 5.5 | 15.3 59.5 207 22 11 9.8 5.4
9500 16.0 60.8 183 13 7 10.1 5.5 | 16.0 60.8 205 22 11 9.8 5.4
9250 16.8 62.2 182 13 7 10.0 5.5 | 16.8 62.2 204 21 11 9.8 5.4
9000 17.5 63.5 181 13 7 10.1 5.6 | 17.5 63.5 203 21 11 9.9 5.4
8750 18.3 64.9 180 13 7 9.8 5.4 | 18.3 64.9 201 21 11 9.7 5.3
8500 19.0 66.2 179 13 7 11.2 6.1 | 19.0 66.2 200 21 11 10.2 5.6
8250 20.1 68.2 178 13 7 17.9 9.8 | 19.8 67.6 199 20 10 12.7 7.0
8000 21.6 70.9 176 12 6 24.6 13.5 | 20.8 69.4 199 17 9 15.3 8.4
7750 23.2 73.8 173 11 5 14.2 7.8 | 21.8 71.2 198 14 7 11.4 6.2
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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