RSS Feeds
Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 191014
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO CO
414 AM MDT WED JUN 19 2013
EXPERIMENTAL PRODUCT
This forecast is for Wednesday June 19, 2013:
If the trigger temperature of 73.5 F/23.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 2172 ft/min (11.0 m/s)
Maximum height of thermals.................. 28710 ft MSL (21051 ft AGL)
Forecast maximum temperature................... 88.0 F/31.6 C
Time of trigger temperature.................... 1000 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 23284 ft MSL (15625 ft AGL)
Thermal soaring outlook for Thursday 06/20..... Excellent
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Neutral
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 27871 ft MSL (20212 ft AGL)
Wave soaring outlook for Thursday 06/20........ Poor
Remarks...
Sunrise/Sunset.................... 05:33:46 / 20:27:34 MDT
Total possible sunshine........... 14 hr 53 min 49 sec (893 min 49 sec)
Altitude of sun at 13:00:47 MDT... 74.42 degrees
Upper air data from numerical model forecast valid on 06/19/2013 at 0600 MDT
Freezing level.................. 15541 ft MSL (7882 ft AGL)
Convective condensation level... 19387 ft MSL (11728 ft AGL)
Lifted condensation level....... 21695 ft MSL (14036 ft AGL)
Lifted index.................... -5.7
K index......................... +5.2
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 -61.6 -78.9 244 31 16 1.9 1.0 81.5 178.7 30.1 M M
45000 -58.5 -73.3 248 47 24 2.2 1.2 62.8 145.0 20.3 M M
40000 -55.1 -67.2 261 49 25 4.4 2.4 46.3 115.3 10.4 M M
38000 -52.1 -61.8 260 46 24 5.0 2.7 41.7 107.0 7.4 M M
36000 -49.1 -56.4 260 42 22 5.0 2.7 37.9 100.2 4.9 M M
34000 -45.0 -49.0 260 39 20 7.9 4.3 35.5 95.8 3.2 M M
32000 -40.2 -40.4 261 37 19 7.9 4.3 34.1 93.3 2.2 M M
30000 -35.7 -32.3 263 38 19 7.4 4.1 32.3 90.2 1.0 M M
29000 -33.5 -28.3 263 39 20 7.4 4.1 31.4 88.6 0.3 M M
28000 -31.2 -24.2 264 40 20 7.3 4.0 30.7 87.2 -0.4 2114 10.7
27000 -28.2 -18.8 263 41 21 8.2 4.5 29.8 85.6 -1.1 1987 10.1
26000 -25.8 -14.4 262 42 22 8.2 4.5 29.2 84.6 -1.6 1883 9.6
25000 -23.3 -9.9 262 43 22 8.3 4.5 28.7 83.7 -2.0 1780 9.0
24000 -20.9 -5.6 261 41 21 7.9 4.3 28.1 82.5 -2.6 1678 8.5
23000 -18.5 -1.3 261 38 20 7.9 4.3 27.4 81.3 -3.2 1578 8.0
22000 -16.2 2.8 261 35 18 7.9 4.3 26.8 80.2 -3.8 1478 7.5
21000 -13.7 7.3 261 34 17 8.5 4.7 26.3 79.3 -4.3 1373 7.0
20000 -11.1 12.0 260 32 17 8.5 4.7 25.9 78.5 -4.7 1267 6.4
19500 -9.9 14.2 260 32 16 8.6 4.7 25.7 78.2 -4.9 1214 6.2
19000 -8.6 16.5 259 31 16 7.8 4.3 25.5 77.9 -5.1 1162 5.9
18500 -7.5 18.5 258 30 15 7.7 4.2 25.1 77.2 -5.5 1114 5.7
18000 -6.4 20.5 257 29 15 7.8 4.3 24.8 76.6 -5.9 1065 5.4
17500 -5.2 22.6 257 28 14 8.4 4.6 24.5 76.1 -6.2 1015 5.2
17000 -4.0 24.8 258 27 14 8.4 4.6 24.3 75.7 -6.4 963 4.9
16500 -2.7 27.1 260 26 13 8.8 4.8 24.1 75.4 -6.7 910 4.6
16000 -1.4 29.5 263 25 13 8.9 4.9 23.9 75.1 -6.8 855 4.3
15500 -0.0 32.0 266 25 13 9.0 4.9 23.8 74.9 -7.0 800 4.1
15000 1.3 34.3 268 24 13 9.0 5.0 23.7 74.6 -7.1 745 3.8
14500 2.7 36.9 271 24 12 9.1 5.0 23.6 74.4 -7.3 689 3.5
14000 4.1 39.4 272 24 12 9.7 5.3 23.5 74.3 -7.4 632 3.2
13500 5.5 41.9 272 23 12 9.6 5.3 23.5 74.3 -7.4 574 2.9
13000 7.0 44.6 271 23 12 9.5 5.2 23.5 74.2 -7.5 516 2.6
12500 8.4 47.1 270 22 11 9.5 5.2 23.4 74.2 -7.6 459 2.3
12000 9.8 49.6 268 21 11 9.7 5.3 23.4 74.1 -7.7 401 2.0
11750 10.6 51.1 267 21 11 9.7 5.3 23.4 74.1 -7.7 372 1.9
11500 11.3 52.3 266 20 11 9.8 5.4 23.4 74.1 -7.7 343 1.7
11250 12.0 53.6 265 20 10 9.6 5.3 23.4 74.1 -7.8 314 1.6
11000 12.7 54.9 263 19 10 8.6 4.7 23.4 74.0 -7.8 287 1.5
10750 13.2 55.8 260 18 9 8.2 4.5 23.2 73.8 -8.0 262 1.3
10500 13.8 56.8 256 17 9 8.4 4.6 23.1 73.6 -8.2 237 1.2
10250 14.4 57.9 253 16 8 8.2 4.5 23.0 73.4 -8.3 212 1.1
10000 15.2 59.4 243 15 8 4.8 2.6 22.5 72.5 -9.1 173 0.9
9750 15.5 59.9 236 14 7 5.5 3.0 22.1 71.8 -9.5 156 0.8
9500 15.8 60.4 230 13 7 4.8 2.6 21.8 71.2 -10.0 139 0.7
9250 16.0 60.8 224 13 7 1.1 0.6 21.3 70.3 -10.6 128 0.6
9000 15.8 60.4 222 13 7 -1.5 -0.8 20.5 68.9 -11.5 125 0.6
8750 15.7 60.3 220 14 7 1.3 0.7 19.7 67.5 -12.4 122 0.6
8500 15.5 59.9 218 14 7 -6.2 -3.4 19.0 66.1 -13.3 119 0.6
8250 14.3 57.7 219 12 6 -24.9 -13.7 17.0 62.7 -15.3 150 0.8
8000 12.0 53.6 223 9 5 -33.4 -18.3 14.0 57.2 -18.4 212 1.1
7750 9.6 49.3 233 6 3 -25.0 -13.7 11.0 51.8 -21.5 274 1.4
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 * * * * * *
06/19/2013 at 0900 MDT | 06/19/2013 at 1200 MDT
|
K index... -1.6 | K index... +2.1
|
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 -60.8 -77.4 232 32 16 1.9 1.1 | -60.9 -77.6 222 34 17 2.0 1.1
45000 -58.4 -73.1 245 44 23 0.1 0.1 | -58.6 -73.5 242 45 23 -0.4 -0.2
40000 -57.9 -72.2 265 38 20 5.5 3.0 | -58.9 -74.0 259 36 19 6.3 3.4
38000 -53.9 -65.0 268 35 18 6.6 3.6 | -54.4 -65.9 257 33 17 7.4 4.1
36000 -49.9 -57.8 272 33 17 6.6 3.6 | -50.0 -58.0 255 31 16 7.4 4.1
34000 -45.2 -49.4 272 31 16 8.4 4.6 | -45.1 -49.2 254 29 15 8.4 4.6
32000 -40.2 -40.4 270 30 16 8.4 4.6 | -40.0 -40.0 254 27 14 8.4 4.6
30000 -35.2 -31.4 268 30 15 8.4 4.6 | -34.9 -30.8 254 28 15 8.4 4.6
29000 -32.7 -26.9 266 30 15 8.4 4.6 | -32.4 -26.3 255 30 15 8.4 4.6
28000 -29.5 -21.1 265 29 15 8.1 4.4 | -29.3 -20.7 255 31 16 8.1 4.4
27000 -27.2 -17.0 264 31 16 7.6 4.2 | -27.0 -16.6 256 33 17 7.7 4.2
26000 -24.9 -12.8 264 32 17 7.6 4.2 | -24.7 -12.5 256 34 18 7.7 4.2
25000 -22.7 -8.9 263 33 17 7.6 4.1 | -22.3 -8.1 257 36 18 7.7 4.2
24000 -20.3 -4.5 262 33 17 8.0 4.4 | -19.9 -3.8 257 36 18 8.3 4.6
23000 -17.9 -0.2 261 33 17 8.0 4.4 | -17.4 0.7 256 35 18 8.3 4.5
22000 -15.5 4.1 260 33 17 8.1 4.4 | -14.9 5.2 255 35 18 8.3 4.5
21000 -12.9 8.8 257 32 17 8.7 4.8 | -12.6 9.3 255 34 18 7.7 4.2
20000 -10.3 13.5 254 32 17 8.7 4.8 | -10.3 13.5 255 33 17 7.7 4.2
19500 -9.0 15.8 253 32 17 8.8 4.8 | -9.2 15.4 255 33 17 7.7 4.2
19000 -7.7 18.1 251 32 17 7.7 4.2 | -8.0 17.6 256 33 17 7.7 4.2
18500 -6.6 20.1 249 33 17 7.5 4.1 | -6.9 19.6 256 32 17 7.7 4.2
18000 -5.5 22.1 247 34 17 7.4 4.0 | -5.7 21.7 256 32 17 7.8 4.3
17500 -4.5 23.9 245 33 17 6.6 3.6 | -4.5 23.9 256 31 16 8.3 4.6
17000 -3.6 25.5 242 32 16 6.6 3.6 | -3.3 26.1 255 29 15 8.3 4.6
16500 -2.5 27.5 239 30 15 8.7 4.8 | -2.1 28.2 253 27 14 8.3 4.6
16000 -1.2 29.8 238 27 14 9.0 4.9 | -0.9 30.4 250 24 13 8.4 4.6
15500 0.1 32.2 236 25 13 8.9 4.9 | 0.3 32.5 246 22 11 8.7 4.8
15000 1.4 34.5 235 23 12 8.7 4.8 | 1.6 34.9 244 21 11 9.0 4.9
14500 2.7 36.9 233 21 11 8.7 4.8 | 3.0 37.4 242 20 10 9.0 5.0
14000 4.1 39.4 235 19 10 8.8 4.8 | 4.3 39.7 239 18 9 9.1 5.0
13500 5.4 41.7 239 18 9 8.8 4.8 | 5.6 42.1 235 17 9 9.1 5.0
13000 6.7 44.1 243 17 9 8.8 4.8 | 7.0 44.6 231 16 8 9.3 5.1
12500 8.0 46.4 246 16 8 8.7 4.8 | 8.4 47.1 226 15 8 9.3 5.1
12000 9.4 48.9 248 16 8 9.9 5.4 | 9.8 49.6 221 14 7 9.6 5.2
11750 10.2 50.4 248 16 8 10.0 5.5 | 10.5 50.9 218 14 7 9.6 5.3
11500 10.9 51.6 247 16 8 10.0 5.5 | 11.2 52.2 215 14 7 9.6 5.3
11250 11.6 52.9 247 16 8 9.8 5.4 | 11.9 53.4 212 14 7 9.7 5.3
11000 12.4 54.3 246 15 8 9.3 5.1 | 12.6 54.7 210 14 7 9.9 5.4
10750 13.0 55.4 245 15 8 9.1 5.0 | 13.4 56.1 208 14 7 10.0 5.5
10500 13.7 56.7 244 15 8 9.2 5.1 | 14.1 57.4 205 14 7 9.9 5.5
10250 15.1 59.2 242 14 7 8.4 4.6 | 15.6 60.1 201 14 7 9.9 5.4
10000 15.6 60.1 240 13 7 8.0 4.4 | 16.3 61.3 199 14 7 9.8 5.4
9750 16.2 61.2 237 12 6 8.3 4.6 | 17.0 62.6 197 14 7 9.8 5.4
9500 16.8 62.2 235 11 6 7.6 4.2 | 17.8 64.0 194 14 7 9.9 5.4
9250 17.2 63.0 232 11 6 5.3 2.9 | 18.5 65.3 193 14 7 10.0 5.5
9000 17.5 63.5 231 11 6 4.5 2.5 | 19.2 66.6 191 14 7 10.3 5.6
8750 17.7 63.9 230 12 6 4.4 2.4 | 20.0 68.0 190 14 7 9.5 5.2
8500 18.0 64.4 228 12 6 6.9 3.8 | 20.7 69.3 188 14 7 12.4 6.8
8250 18.6 65.5 226 11 6 12.1 6.6 | 21.9 71.4 187 13 7 19.7 10.8
8000 19.4 66.9 220 8 4 13.4 7.3 | 23.5 74.3 185 12 6 23.1 12.7
7750 20.2 68.4 209 6 3 14.2 7.8 | 25.1 77.2 183 11 6 19.9 10.9
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
06/19/2013 at 1500 MDT | 06/19/2013 at 1800 MDT
|
K index... +14.3 | K index... +10.5
|
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 -61.1 -78.0 236 37 19 1.6 0.9 | -61.9 -79.4 246 36 19 0.4 0.2
45000 -59.3 -74.7 247 47 24 -0.4 -0.2 | -61.0 -77.8 257 47 24 1.2 0.7
40000 -59.4 -74.9 257 41 21 7.7 4.2 | -58.8 -73.8 261 47 24 8.0 4.4
38000 -54.5 -66.1 258 39 20 8.1 4.5 | -54.1 -65.4 260 43 22 7.9 4.3
36000 -49.6 -57.3 258 37 19 8.1 4.5 | -49.3 -56.7 258 38 20 7.9 4.3
34000 -44.7 -48.5 258 35 18 8.4 4.6 | -44.6 -48.3 256 37 19 7.9 4.4
32000 -39.6 -39.3 258 31 16 8.4 4.6 | -39.8 -39.6 253 36 19 8.0 4.4
30000 -34.8 -30.6 260 32 16 8.0 4.4 | -34.7 -30.5 254 35 18 8.8 4.8
29000 -32.3 -26.1 261 33 17 8.0 4.4 | -32.0 -25.6 255 34 17 8.8 4.8
28000 -29.3 -20.7 262 34 17 7.8 4.3 | -29.4 -20.9 256 33 17 9.0 4.9
27000 -27.1 -16.8 261 35 18 7.5 4.1 | -26.4 -15.5 258 34 17 7.7 4.2
26000 -24.8 -12.6 260 37 19 7.5 4.1 | -24.1 -11.4 260 34 18 7.7 4.2
25000 -22.6 -8.7 260 39 20 7.5 4.1 | -21.8 -7.2 262 35 18 7.7 4.2
24000 -20.1 -4.2 259 39 20 8.4 4.6 | -19.7 -3.5 262 33 17 7.1 3.9
23000 -17.6 0.3 258 39 20 8.4 4.6 | -17.6 0.3 262 31 16 7.1 3.9
22000 -15.1 4.8 258 39 20 8.3 4.6 | -15.5 4.1 261 29 15 7.4 4.1
21000 -12.7 9.1 258 36 18 8.1 4.4 | -12.9 8.8 257 27 14 8.9 4.9
20000 -10.3 13.5 257 32 17 8.2 4.5 | -10.3 13.5 251 24 13 9.0 4.9
19500 -9.1 15.6 257 30 16 8.2 4.5 | -9.0 15.8 248 23 12 9.0 4.9
19000 -7.9 17.8 256 29 15 8.6 4.7 | -7.6 18.3 246 23 12 9.6 5.3
18500 -6.7 19.9 253 27 14 8.6 4.7 | -6.2 20.8 245 23 12 9.7 5.3
18000 -5.4 22.3 250 25 13 8.8 4.9 | -4.7 23.5 244 23 12 9.7 5.3
17500 -4.1 24.6 248 24 12 9.3 5.1 | -3.3 26.1 243 23 12 9.8 5.4
17000 -2.7 27.1 246 23 12 9.3 5.1 | -1.8 28.8 241 23 12 9.8 5.4
16500 -1.3 29.7 243 23 12 9.5 5.2 | -0.4 31.3 238 23 12 9.5 5.2
16000 0.1 32.2 240 22 12 9.6 5.2 | 1.1 34.0 235 23 12 9.5 5.2
15500 1.5 34.7 237 22 11 9.5 5.2 | 2.5 36.5 233 24 12 9.6 5.3
15000 2.9 37.2 235 22 11 9.5 5.2 | 4.0 39.2 231 24 12 9.7 5.3
14500 4.4 39.9 233 22 11 9.5 5.2 | 5.4 41.7 230 24 12 9.7 5.3
14000 5.8 42.4 231 22 11 9.9 5.4 | 6.9 44.4 228 24 12 9.5 5.2
13500 7.3 45.1 228 22 11 9.9 5.4 | 8.3 46.9 226 24 12 9.5 5.2
13000 8.7 47.7 225 21 11 9.8 5.4 | 9.7 49.5 224 24 12 9.8 5.4
12500 10.2 50.4 222 21 11 9.8 5.4 | 11.2 52.2 221 24 12 9.8 5.4
12000 11.7 53.1 218 21 11 9.7 5.3 | 12.6 54.7 219 24 12 9.8 5.4
11750 12.4 54.3 216 21 11 9.7 5.3 | 13.4 56.1 218 24 12 9.8 5.4
11500 13.1 55.6 213 20 11 9.7 5.3 | 14.1 57.4 217 24 12 9.8 5.4
11250 13.8 56.8 210 20 10 9.7 5.3 | 14.8 58.6 216 23 12 9.8 5.4
11000 14.6 58.3 208 20 10 9.8 5.4 | 15.5 59.9 214 23 12 9.7 5.3
10750 15.3 59.5 207 20 10 9.9 5.4 | 16.3 61.3 212 23 12 9.6 5.3
10500 16.0 60.8 206 20 10 9.8 5.4 | 17.0 62.6 211 23 12 9.7 5.3
10250 17.5 63.5 203 20 10 9.9 5.4 | 18.4 65.1 207 23 12 9.7 5.3
10000 18.3 64.9 202 20 10 10.0 5.5 | 19.2 66.6 206 23 12 9.7 5.3
9750 19.0 66.2 201 20 10 9.9 5.5 | 19.9 67.8 204 22 12 9.7 5.3
9500 19.8 67.6 200 20 10 10.0 5.5 | 20.6 69.1 203 22 11 9.7 5.3
9250 20.5 68.9 199 20 10 10.2 5.6 | 21.4 70.5 202 22 11 9.8 5.4
9000 21.3 70.3 198 20 10 10.5 5.7 | 22.1 71.8 200 22 11 9.9 5.4
8750 22.0 71.6 197 20 10 9.9 5.4 | 22.8 73.0 199 22 11 9.8 5.4
8500 22.8 73.0 196 19 10 12.0 6.6 | 23.6 74.5 198 21 11 10.3 5.6
8250 23.9 75.0 195 19 10 18.8 10.3 | 24.4 75.9 197 20 10 13.0 7.1
8000 25.5 77.9 194 17 9 23.8 13.1 | 25.4 77.7 197 17 9 15.9 8.7
7750 27.1 80.8 193 15 8 17.0 9.3 | 26.5 79.7 197 15 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.
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