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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 241041
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO CO
441 AM MDT FRI MAY 24 2013
EXPERIMENTAL PRODUCT
This forecast is for Friday May 24, 2013:
If the trigger temperature of 67.4 F/19.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1361 ft/min (6.9 m/s)
Maximum height of thermals.................. 23178 ft MSL (15518 ft AGL)
Forecast maximum temperature................... 78.0 F/26.0 C
Time of trigger temperature.................... 1030 MDT
Time of overdevelopment........................ None
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................. 17584 ft MSL (9924 ft AGL)
Thermal soaring outlook for Saturday 05/25..... Excellent
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)................ Neither
Potential height of wave....................... 14785 ft MSL (7125 ft AGL)
Wave soaring outlook for Saturday 05/25........ Poor
Remarks...
Sunrise/Sunset.................... 05:39:43 / 20:12:26 MDT
Total possible sunshine........... 14 hr 32 min 43 sec (872 min 43 sec)
Altitude of sun at 12:56:16 MDT... 71.90 degrees
Upper air data from numerical model forecast valid on 05/24/2013 at 0600 MDT
Freezing level.................. 14842 ft MSL (7182 ft AGL)
Convective condensation level... 18983 ft MSL (11323 ft AGL)
Lifted condensation level....... 20207 ft MSL (12547 ft AGL)
Lifted index.................... -2.6
K index......................... +2.6
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 -61.9 -79.4 243 30 15 -0.4 -0.2 82.5 180.6 33.9 M M
45000 -62.3 -80.1 237 40 21 0.4 0.2 59.7 139.5 21.7 M M
40000 -61.7 -79.1 230 30 16 -0.4 -0.2 38.4 101.2 8.7 M M
38000 -57.1 -70.8 227 26 14 7.9 4.3 35.3 95.6 6.9 M M
36000 -52.4 -62.3 223 23 12 7.9 4.3 33.9 93.1 6.0 M M
34000 -47.5 -53.5 220 20 10 8.2 4.5 32.5 90.6 5.2 M M
32000 -42.6 -44.7 217 16 8 8.2 4.5 31.4 88.5 4.4 M M
30000 -37.5 -35.5 225 15 8 8.8 4.8 30.4 86.8 3.8 M M
29000 -34.9 -30.8 234 16 8 8.8 4.8 30.0 86.1 3.5 M M
28000 -32.2 -26.0 241 17 9 8.8 4.8 29.8 85.6 3.4 M M
27000 -29.9 -21.8 245 20 10 7.4 4.1 29.1 84.3 2.8 M M
26000 -27.7 -17.9 246 24 12 7.4 4.0 28.1 82.6 2.1 M M
25000 -25.5 -13.9 247 28 15 7.4 4.0 27.3 81.2 1.4 M M
24000 -23.3 -9.9 245 32 17 7.3 4.0 26.5 79.7 0.8 M M
23000 -20.5 -4.9 239 37 19 7.3 4.0 25.3 77.6 -0.2 1533 7.8
22000 -18.4 -1.1 235 41 21 7.3 4.0 24.6 76.2 -0.9 1438 7.3
21000 -16.0 3.2 230 42 22 8.2 4.5 23.9 75.0 -1.5 1338 6.8
20000 -13.6 7.5 226 43 22 8.2 4.5 23.4 74.1 -2.0 1236 6.3
19500 -12.4 9.7 224 43 22 8.2 4.5 23.1 73.7 -2.3 1185 6.0
19000 -11.2 11.8 222 43 22 8.6 4.7 22.9 73.3 -2.5 1134 5.8
18500 -9.9 14.2 220 40 20 8.7 4.8 22.7 72.9 -2.7 1081 5.5
18000 -8.6 16.5 218 36 19 8.7 4.8 22.6 72.6 -2.9 1028 5.2
17500 -7.2 19.0 217 36 18 9.4 5.1 22.5 72.4 -3.0 972 4.9
17000 -5.9 21.4 216 36 19 9.3 5.1 22.4 72.3 -3.1 916 4.7
16500 -4.5 23.9 216 37 19 9.2 5.1 22.3 72.2 -3.2 859 4.4
16000 -3.1 26.4 218 35 18 9.2 5.0 22.2 72.0 -3.3 803 4.1
15500 -1.7 28.9 220 34 17 8.7 4.8 22.2 71.9 -3.4 746 3.8
15000 -0.5 31.1 223 35 18 7.9 4.3 21.9 71.4 -3.6 695 3.5
14500 0.7 33.3 225 35 18 7.9 4.3 21.6 70.8 -3.9 644 3.3
14000 1.9 35.4 226 35 18 7.6 4.2 21.3 70.3 -4.2 595 3.0
13500 3.1 37.6 226 34 18 7.7 4.2 20.9 69.7 -4.5 545 2.8
13000 4.2 39.6 226 33 17 7.7 4.2 20.6 69.1 -4.9 496 2.5
12500 5.3 41.5 226 31 16 7.6 4.2 20.3 68.5 -5.2 448 2.3
12000 6.5 43.7 225 30 15 9.0 4.9 20.0 68.0 -5.5 397 2.0
11750 7.2 45.0 225 29 15 9.2 5.1 20.0 68.0 -5.6 370 1.9
11500 7.9 46.2 225 28 15 9.2 5.0 19.9 67.9 -5.7 342 1.7
11250 8.5 47.3 224 28 14 9.2 5.0 19.9 67.8 -5.7 315 1.6
11000 9.2 48.6 224 27 14 9.1 5.0 19.8 67.7 -5.8 287 1.5
10750 9.9 49.8 224 27 14 9.0 4.9 19.8 67.6 -5.9 260 1.3
10500 10.5 50.9 224 26 14 9.2 5.1 19.7 67.5 -6.0 233 1.2
10250 11.2 52.2 224 26 13 8.5 4.6 19.7 67.4 -6.1 206 1.0
10000 11.7 53.1 224 26 13 5.4 2.9 19.5 67.1 -6.4 184 0.9
9750 11.9 53.4 225 25 13 3.7 2.0 19.0 66.3 -6.9 169 0.9
9500 12.4 54.3 227 25 13 2.4 1.3 18.2 64.8 -7.9 139 0.7
9250 12.3 54.1 228 24 12 -4.4 -2.4 17.4 63.3 -8.8 137 0.7
9000 11.7 53.1 229 24 12 -7.1 -3.9 16.2 61.1 -10.1 147 0.7
8750 11.1 52.0 230 23 12 -5.5 -3.0 14.9 58.9 -11.5 157 0.8
8500 10.5 50.9 232 22 11 -8.3 -4.6 13.7 56.7 -12.8 167 0.8
8250 9.6 49.3 232 18 9 -13.0 -7.1 12.2 53.9 -14.5 188 1.0
8000 8.5 47.3 229 12 6 -12.7 -7.0 10.4 50.8 -16.3 213 1.1
7750 7.4 45.3 222 6 3 -15.4 -8.5 8.7 47.7 -18.2 238 1.2
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 * * * * * *
05/24/2013 at 0900 MDT | 05/24/2013 at 1200 MDT
|
K index... -7.4 | K index... +2.0
|
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 -61.6 -78.9 247 31 16 -0.1 -0.1 | -61.0 -77.8 246 29 15 -0.7 -0.4
45000 -61.8 -79.2 238 48 25 -0.2 -0.1 | -62.0 -79.6 249 46 24 0.2 0.1
40000 -62.1 -79.8 219 36 19 -0.8 -0.5 | -61.6 -78.9 228 44 23 -0.2 -0.1
38000 -57.7 -71.9 219 33 17 7.7 4.2 | -57.5 -71.5 226 39 20 7.0 3.8
36000 -53.1 -63.6 221 29 15 7.7 4.2 | -53.3 -63.9 227 34 18 7.0 3.8
34000 -48.3 -54.9 226 27 14 8.4 4.6 | -48.7 -55.7 229 31 16 8.1 4.5
32000 -43.2 -45.8 235 25 13 8.5 4.6 | -43.9 -47.0 233 29 15 8.1 4.5
30000 -38.2 -36.8 242 24 13 8.4 4.6 | -38.8 -37.8 234 28 14 8.7 4.8
29000 -35.7 -32.3 244 24 13 8.4 4.6 | -36.2 -33.2 233 28 14 8.7 4.8
28000 -33.2 -27.8 247 25 13 8.4 4.6 | -33.6 -28.5 233 28 14 8.8 4.8
27000 -30.7 -23.3 247 25 13 8.2 4.5 | -31.0 -23.8 233 29 15 8.2 4.5
26000 -28.2 -18.8 245 27 14 8.2 4.5 | -28.6 -19.5 235 30 16 8.2 4.5
25000 -25.7 -14.3 243 28 15 8.2 4.5 | -26.1 -15.0 236 32 16 8.2 4.5
24000 -22.8 -9.0 239 30 16 7.4 4.0 | -23.0 -9.4 236 34 17 8.3 4.5
23000 -20.6 -5.1 236 32 17 7.4 4.0 | -20.6 -5.1 236 35 18 8.3 4.5
22000 -18.4 -1.1 233 35 18 7.3 4.0 | -18.1 -0.6 236 36 18 8.3 4.5
21000 -16.0 3.2 229 35 18 8.2 4.5 | -15.7 3.7 236 37 19 8.0 4.4
20000 -13.6 7.5 224 35 18 8.2 4.5 | -13.3 8.1 235 37 19 8.0 4.4
19500 -12.4 9.7 222 35 18 8.2 4.5 | -12.1 10.2 235 38 19 8.0 4.4
19000 -11.2 11.8 219 35 18 8.3 4.6 | -11.0 12.2 234 38 20 7.3 4.0
18500 -9.9 14.2 217 35 18 8.3 4.6 | -9.9 14.2 234 39 20 7.2 4.0
18000 -8.7 16.3 215 35 18 8.4 4.6 | -8.8 16.2 234 40 21 7.4 4.1
17500 -7.4 18.7 216 36 18 8.7 4.8 | -7.7 18.1 234 41 21 8.0 4.4
17000 -6.1 21.0 217 37 19 8.6 4.7 | -6.5 20.3 234 42 22 8.0 4.4
16500 -4.8 23.4 218 38 20 8.9 4.9 | -5.3 22.5 234 42 21 8.5 4.6
16000 -3.5 25.7 218 37 19 9.0 4.9 | -4.1 24.6 235 40 21 8.5 4.7
15500 -2.1 28.2 218 37 19 8.9 4.9 | -2.8 27.0 235 38 20 8.6 4.7
15000 -0.8 30.6 220 36 19 8.8 4.8 | -1.6 29.1 236 35 18 8.7 4.8
14500 0.5 32.9 222 36 18 8.8 4.8 | -0.3 31.5 237 32 16 8.8 4.8
14000 1.8 35.2 224 36 18 8.6 4.7 | 1.0 33.8 237 29 15 9.4 5.2
13500 3.1 37.6 226 36 19 8.8 4.8 | 2.4 36.3 238 26 13 9.4 5.1
13000 4.2 39.6 228 36 19 6.9 3.8 | 3.8 38.8 238 23 12 9.8 5.4
12500 5.3 41.5 232 35 18 7.1 3.9 | 5.2 41.4 238 21 11 9.8 5.4
12000 6.4 43.5 235 34 17 7.3 4.0 | 6.7 44.1 237 20 10 9.4 5.2
11750 6.9 44.4 237 33 17 7.3 4.0 | 7.4 45.3 236 19 10 9.4 5.2
11500 7.5 45.5 238 31 16 7.2 4.0 | 8.1 46.6 235 18 9 9.4 5.2
11250 8.0 46.4 240 30 16 7.4 4.0 | 8.7 47.7 234 17 9 9.6 5.3
11000 8.6 47.5 241 29 15 7.7 4.2 | 9.5 49.1 232 16 8 9.9 5.4
10750 9.1 48.4 241 27 14 7.7 4.3 | 10.2 50.4 229 15 8 9.9 5.4
10500 9.7 49.5 241 25 13 7.8 4.3 | 10.9 51.6 226 14 7 9.9 5.4
10250 10.2 50.4 241 23 12 7.7 4.2 | 11.6 52.9 223 14 7 9.8 5.4
10000 10.8 51.4 241 22 11 7.7 4.2 | 12.4 54.3 219 13 7 9.6 5.3
9750 11.8 53.2 241 19 10 8.1 4.4 | 13.8 56.8 211 12 6 9.6 5.3
9500 12.4 54.3 241 17 9 6.6 3.6 | 14.5 58.1 207 12 6 9.8 5.4
9250 12.7 54.9 241 16 8 4.0 2.2 | 15.2 59.4 205 12 6 9.9 5.4
9000 12.9 55.2 242 15 7 4.1 2.3 | 15.9 60.6 202 12 6 10.3 5.6
8750 13.1 55.6 243 13 7 3.2 1.8 | 16.7 62.1 200 11 6 8.8 4.8
8500 13.2 55.8 245 12 6 8.1 4.5 | 17.4 63.3 198 11 6 14.5 7.9
8250 14.1 57.4 242 10 5 14.8 8.1 | 18.8 65.8 197 11 6 22.0 12.0
8000 15.1 59.2 236 8 4 11.7 6.4 | 20.3 68.5 196 10 5 17.3 9.5
7750 16.0 60.8 227 6 3 21.7 11.9 | 21.8 71.2 195 10 5 30.7 16.9
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
05/24/2013 at 1500 MDT | 05/24/2013 at 1800 MDT
|
K index... +17.9 | K index... +19.5
|
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 -60.9 -77.6 246 31 16 0.7 0.4 | -61.6 -78.9 246 32 17 0.7 0.4
45000 -60.1 -76.2 253 43 22 -1.1 -0.6 | -60.8 -77.4 238 34 17 -0.3 -0.2
40000 -61.8 -79.2 238 52 27 1.2 0.7 | -61.3 -78.3 242 51 26 -1.2 -0.6
38000 -57.7 -71.9 238 46 24 7.3 4.0 | -57.1 -70.8 241 48 25 7.1 3.9
36000 -53.3 -63.9 238 40 21 7.3 4.0 | -52.8 -63.0 240 44 22 7.1 3.9
34000 -48.6 -55.5 238 37 19 8.2 4.5 | -48.2 -54.8 238 41 21 8.2 4.5
32000 -43.7 -46.7 237 35 18 8.2 4.5 | -43.3 -45.9 236 39 20 8.2 4.5
30000 -38.7 -37.7 238 33 17 8.5 4.7 | -38.3 -36.9 236 38 19 8.5 4.7
29000 -36.1 -33.0 238 33 17 8.5 4.7 | -35.7 -32.3 236 37 19 8.5 4.7
28000 -33.5 -28.3 239 32 16 8.6 4.7 | -33.2 -27.8 236 36 19 8.6 4.7
27000 -31.0 -23.8 240 32 17 8.2 4.5 | -30.7 -23.3 237 36 19 8.0 4.4
26000 -28.6 -19.5 242 33 17 8.2 4.5 | -28.3 -18.9 239 36 19 8.0 4.4
25000 -25.5 -13.9 243 35 18 8.3 4.6 | -25.9 -14.6 241 36 19 8.0 4.4
24000 -23.1 -9.6 244 36 18 7.7 4.2 | -23.1 -9.6 243 37 19 7.4 4.0
23000 -20.8 -5.4 244 37 19 7.7 4.2 | -20.9 -5.6 244 37 19 7.4 4.1
22000 -18.5 -1.3 244 38 20 7.7 4.2 | -18.7 -1.7 246 37 19 7.5 4.1
21000 -16.1 3.0 244 38 20 8.3 4.5 | -16.2 2.8 246 35 18 8.7 4.8
20000 -13.6 7.5 245 38 20 8.3 4.6 | -13.7 7.3 245 32 16 8.8 4.8
19500 -12.4 9.7 245 38 20 8.3 4.6 | -12.4 9.7 245 30 15 8.9 4.9
19000 -11.2 11.8 245 37 19 8.2 4.5 | -11.1 12.0 245 29 15 9.2 5.0
18500 -10.0 14.0 244 35 18 8.3 4.6 | -9.7 14.5 244 28 14 9.2 5.0
18000 -8.8 16.2 244 33 17 8.6 4.7 | -8.4 16.9 244 27 14 9.3 5.1
17500 -7.5 18.5 243 31 16 9.1 5.0 | -6.9 19.6 244 27 14 9.8 5.4
17000 -6.2 20.8 243 30 15 9.1 5.0 | -5.5 22.1 243 26 13 9.8 5.4
16500 -4.9 23.2 242 29 15 9.3 5.1 | -4.1 24.6 242 25 13 9.4 5.2
16000 -3.5 25.7 242 27 14 9.3 5.1 | -2.7 27.1 241 25 13 9.4 5.2
15500 -2.1 28.2 241 26 13 9.6 5.3 | -1.3 29.7 240 24 12 9.5 5.2
15000 -0.7 30.7 240 25 13 9.8 5.4 | 0.1 32.2 238 23 12 9.6 5.3
14500 0.8 33.4 239 25 13 9.8 5.4 | 1.6 34.9 237 23 12 9.6 5.3
14000 2.2 36.0 237 24 12 9.6 5.3 | 3.0 37.4 234 22 11 9.4 5.1
13500 3.6 38.5 235 23 12 9.6 5.3 | 4.4 39.9 231 22 11 9.4 5.1
13000 5.1 41.2 232 22 12 9.5 5.2 | 5.8 42.4 228 21 11 9.3 5.1
12500 6.5 43.7 229 22 11 9.5 5.2 | 7.1 44.8 225 20 11 9.3 5.1
12000 7.9 46.2 226 21 11 9.6 5.3 | 8.5 47.3 221 20 10 9.3 5.1
11750 8.6 47.5 223 21 11 9.6 5.3 | 9.2 48.6 218 20 10 9.3 5.1
11500 9.3 48.7 221 20 10 9.6 5.3 | 9.9 49.8 216 19 10 9.3 5.1
11250 10.0 50.0 218 20 10 9.7 5.3 | 10.6 51.1 213 19 10 9.4 5.1
11000 10.8 51.4 215 20 10 9.7 5.3 | 11.3 52.3 211 19 10 9.5 5.2
10750 11.5 52.7 213 20 10 9.7 5.3 | 12.0 53.6 209 19 10 9.5 5.2
10500 12.2 54.0 211 19 10 9.7 5.3 | 12.7 54.9 207 18 9 9.5 5.2
10250 12.9 55.2 208 19 10 9.9 5.4 | 13.4 56.1 204 18 9 9.5 5.2
10000 13.7 56.7 206 19 10 10.2 5.6 | 14.1 57.4 201 18 9 9.5 5.2
9750 15.2 59.4 204 19 10 10.3 5.7 | 15.5 59.9 195 18 9 9.5 5.2
9500 16.0 60.8 202 19 10 10.2 5.6 | 16.2 61.2 192 18 9 9.6 5.3
9250 16.7 62.1 201 19 10 10.0 5.5 | 16.9 62.4 190 18 9 9.7 5.3
9000 17.5 63.5 200 19 10 10.3 5.6 | 17.6 63.7 188 17 9 9.9 5.4
8750 18.2 64.8 199 19 10 9.0 4.9 | 18.4 65.1 187 17 9 9.4 5.1
8500 19.0 66.2 198 18 9 13.8 7.6 | 19.1 66.4 185 17 9 11.3 6.2
8250 20.3 68.5 197 17 9 21.0 11.5 | 20.0 68.0 184 16 8 14.1 7.8
8000 21.8 71.2 196 16 8 18.6 10.2 | 21.0 69.8 183 14 7 13.2 7.2
7750 23.2 73.8 194 14 7 27.4 15.0 | 22.0 71.6 182 12 6 16.7 9.1
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.
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