Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 181131
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO CO
531 AM MDT SAT MAY 18 2013
EXPERIMENTAL PRODUCT
This forecast is for Saturday May 18, 2013:
If the trigger temperature of 64.5 F/18.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1506 ft/min (7.7 m/s)
Maximum height of thermals.................. 24341 ft MSL (16678 ft AGL)
Forecast maximum temperature................... 75.0 F/24.3 C
Time of trigger temperature.................... 0830 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................. 19766 ft MSL (12104 ft AGL)
Thermal soaring outlook for Sunday 05/19....... 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)................ Neither
Potential height of wave....................... 21934 ft MSL (14271 ft AGL)
Wave soaring outlook for Sunday 05/19.......... Poor
Remarks...
Sunrise/Sunset.................... 05:43:59 / 20:07:18 MDT
Total possible sunshine........... 14 hr 23 min 19 sec (863 min 19 sec)
Altitude of sun at 12:55:50 MDT... 70.71 degrees
Upper air data from numerical model forecast valid on 05/18/2013 at 0600 MDT
Freezing level.................. 14084 ft MSL (6421 ft AGL)
Convective condensation level... 20998 ft MSL (13335 ft AGL)
Lifted condensation level....... 22201 ft MSL (14538 ft AGL)
Lifted index.................... -0.9
K index......................... +12.9
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 -57.8 -72.0 247 18 9 1.3 0.7 89.4 192.9 38.9 M M
45000 -56.5 -69.7 233 26 14 -2.6 -1.4 69.5 157.1 28.8 M M
40000 -60.5 -76.9 205 47 24 -3.4 -1.9 39.9 103.9 10.9 M M
38000 -57.0 -70.6 205 48 25 7.5 4.1 36.3 97.3 8.7 M M
36000 -52.5 -62.5 206 47 24 7.5 4.1 34.5 94.1 7.6 M M
34000 -48.0 -54.4 205 46 23 7.4 4.1 32.7 90.8 6.5 M M
32000 -43.6 -46.5 199 44 22 7.4 4.1 30.8 87.5 5.2 M M
30000 -39.0 -38.2 196 42 22 8.0 4.4 29.2 84.6 4.1 M M
29000 -36.6 -33.9 196 41 21 8.0 4.4 28.5 83.3 3.6 M M
28000 -34.2 -29.6 195 41 21 7.9 4.4 27.9 82.2 3.2 M M
27000 -31.9 -25.4 196 40 21 6.5 3.6 27.1 80.8 2.6 M M
26000 -30.0 -22.0 198 39 20 6.6 3.6 25.9 78.6 1.6 M M
25000 -27.5 -17.5 200 38 20 6.7 3.6 24.5 76.1 0.5 M M
24000 -25.4 -13.7 201 39 20 7.4 4.0 23.5 74.3 -0.4 1664 8.5
23000 -23.3 -9.9 202 40 21 7.4 4.1 22.6 72.7 -1.2 1569 8.0
22000 -21.1 -6.0 202 42 22 7.5 4.1 21.8 71.3 -1.9 1475 7.5
21000 -18.7 -1.7 202 41 21 8.6 4.7 21.3 70.3 -2.5 1374 7.0
20000 -16.2 2.8 202 38 19 8.7 4.7 20.8 69.5 -2.9 1267 6.4
19500 -14.9 5.2 201 36 19 8.7 4.8 20.7 69.2 -3.1 1214 6.2
19000 -13.6 7.5 201 34 18 8.9 4.9 20.5 69.0 -3.3 1161 5.9
18500 -12.2 10.0 201 33 17 9.4 5.2 20.5 68.8 -3.4 1105 5.6
18000 -10.8 12.6 201 32 16 9.4 5.1 20.4 68.7 -3.5 1049 5.3
17500 -9.4 15.1 202 31 16 9.6 5.3 20.4 68.7 -3.5 991 5.0
17000 -8.0 17.6 202 30 15 9.6 5.3 20.3 68.6 -3.6 933 4.7
16500 -6.5 20.3 202 29 15 9.3 5.1 20.3 68.6 -3.6 875 4.4
16000 -5.2 22.6 202 28 14 8.9 4.9 20.2 68.3 -3.7 820 4.2
15500 -3.8 25.2 202 26 13 8.9 4.9 20.0 68.1 -3.9 765 3.9
15000 -2.5 27.5 204 24 13 8.6 4.7 19.9 67.8 -4.0 711 3.6
14500 -1.2 29.8 208 23 12 8.6 4.7 19.7 67.5 -4.2 657 3.3
14000 0.1 32.2 213 21 11 8.3 4.6 19.5 67.1 -4.4 604 3.1
13500 1.3 34.3 219 19 10 8.3 4.5 19.3 66.7 -4.7 552 2.8
13000 2.6 36.7 226 17 9 8.4 4.6 19.0 66.3 -4.9 500 2.5
12500 3.8 38.8 230 15 8 8.5 4.6 18.8 65.9 -5.1 447 2.3
12000 5.1 41.2 234 13 6 8.2 4.5 18.6 65.5 -5.3 394 2.0
11750 5.7 42.3 237 12 6 8.0 4.4 18.5 65.3 -5.5 369 1.9
11500 6.3 43.3 240 11 6 8.0 4.4 18.4 65.0 -5.6 343 1.7
11250 6.9 44.4 243 10 5 8.2 4.5 18.2 64.8 -5.8 318 1.6
11000 7.5 45.5 247 10 5 7.4 4.1 18.1 64.6 -5.9 293 1.5
10750 8.0 46.4 255 10 5 6.6 3.6 17.9 64.1 -6.2 270 1.4
10500 8.5 47.3 262 10 5 6.8 3.7 17.6 63.7 -6.4 248 1.3
10250 9.0 48.2 269 10 5 6.5 3.6 17.4 63.3 -6.6 225 1.1
10000 10.1 50.2 279 10 5 8.5 4.6 17.0 62.7 -7.0 177 0.9
9750 10.7 51.3 282 9 5 8.2 4.5 16.9 62.5 -7.1 151 0.8
9500 11.4 52.5 285 9 5 8.6 4.7 16.8 62.3 -7.3 125 0.6
9250 12.0 53.6 289 8 4 6.4 3.5 16.7 62.0 -7.4 99 0.5
9000 12.3 54.1 291 10 5 4.0 2.2 16.3 61.3 -7.8 82 0.4
8750 12.6 54.7 293 12 6 5.5 3.0 15.9 60.6 -8.3 65 0.3
8500 13.0 55.4 294 14 7 1.9 1.1 15.5 60.0 -8.7 47 0.2
8250 12.4 54.3 293 14 7 -22.2 -12.2 14.2 57.6 -10.0 58 0.3
8000 9.4 48.9 286 12 6 -51.4 -28.2 10.6 51.1 -13.7 138 0.7
7750 6.5 43.7 275 9 5 -2.6 -1.4 7.0 44.6 -17.4 218 1.1
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 * * * * * *
05/18/2013 at 0900 MDT | 05/18/2013 at 1200 MDT
|
K index... +15.3 | K index... +18.1
|
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 -57.1 -70.8 246 17 9 2.6 1.4 | -56.4 -69.5 245 17 9 2.0 1.1
45000 -53.9 -65.0 231 23 12 -3.2 -1.7 | -53.9 -65.0 243 25 13 -2.2 -1.2
40000 -58.9 -74.0 209 52 27 -3.6 -2.0 | -57.2 -71.0 209 48 25 -2.2 -1.2
38000 -56.4 -69.5 205 55 28 5.9 3.2 | -55.6 -68.1 203 54 28 4.0 2.2
36000 -52.9 -63.2 201 56 29 5.9 3.2 | -53.2 -63.8 199 58 30 4.0 2.2
34000 -48.9 -56.0 199 56 29 7.7 4.2 | -49.8 -57.6 197 60 31 8.1 4.5
32000 -44.3 -47.7 197 53 27 7.7 4.2 | -45.0 -49.0 197 57 30 8.1 4.5
30000 -39.8 -39.6 196 51 26 7.1 3.9 | -40.1 -40.2 199 54 28 8.1 4.4
29000 -37.7 -35.9 196 50 26 7.1 3.9 | -37.7 -35.9 200 52 27 8.1 4.4
28000 -35.6 -32.1 195 50 26 7.1 3.9 | -35.3 -31.5 202 51 26 8.1 4.4
27000 -33.4 -28.1 195 48 25 7.8 4.3 | -33.0 -27.4 203 49 25 6.2 3.4
26000 -31.1 -24.0 196 47 24 7.7 4.2 | -31.1 -24.0 201 49 25 6.4 3.5
25000 -28.2 -18.8 197 44 23 7.7 4.2 | -28.7 -19.7 199 49 25 6.4 3.5
24000 -26.0 -14.8 198 43 22 7.2 4.0 | -26.7 -16.1 197 47 24 7.2 3.9
23000 -23.8 -10.8 196 42 22 7.3 4.0 | -24.6 -12.3 196 41 21 7.2 3.9
22000 -21.7 -7.1 195 42 21 7.4 4.1 | -22.5 -8.5 196 36 18 7.2 4.0
21000 -19.4 -2.9 194 39 20 8.3 4.6 | -20.2 -4.4 193 32 16 8.0 4.4
20000 -16.9 1.6 193 36 18 8.4 4.6 | -17.9 -0.2 190 30 16 8.1 4.4
19500 -15.7 3.7 193 34 17 8.4 4.6 | -16.7 1.9 188 29 15 8.1 4.4
19000 -14.4 6.1 192 32 16 8.5 4.6 | -15.5 4.1 186 29 15 8.2 4.5
18500 -13.2 8.2 192 30 15 8.6 4.7 | -14.2 6.4 185 27 14 9.0 4.9
18000 -11.9 10.6 193 28 14 8.6 4.7 | -12.9 8.8 186 26 14 9.0 4.9
17500 -10.6 12.9 194 26 13 8.7 4.8 | -11.5 11.3 187 25 13 8.4 4.6
17000 -9.3 15.3 195 25 13 8.7 4.8 | -10.3 13.5 190 22 11 8.3 4.6
16500 -8.0 17.6 196 23 12 8.8 4.8 | -9.1 15.6 194 19 10 8.6 4.7
16000 -6.6 20.1 198 21 11 9.0 4.9 | -7.7 18.1 196 16 8 9.1 5.0
15500 -5.3 22.5 200 19 10 9.0 4.9 | -6.4 20.5 198 13 7 9.1 5.0
15000 -4.0 24.8 203 17 9 8.2 4.5 | -5.0 23.0 200 11 6 9.3 5.1
14500 -2.7 27.1 206 14 7 8.2 4.5 | -3.7 25.3 201 8 4 9.3 5.1
14000 -1.5 29.3 208 12 6 8.8 4.8 | -2.3 27.9 201 7 3 9.7 5.3
13500 -0.2 31.6 204 10 5 8.8 4.9 | -0.8 30.6 202 6 3 9.7 5.3
13000 1.1 34.0 201 8 4 8.5 4.7 | 0.6 33.1 203 6 3 9.7 5.3
12500 2.4 36.3 205 8 4 8.5 4.6 | 2.1 35.8 202 5 3 9.7 5.3
12000 3.6 38.5 211 7 4 8.1 4.4 | 3.5 38.3 201 5 2 10.0 5.5
11750 4.2 39.6 218 7 3 7.7 4.2 | 4.3 39.7 201 5 2 10.2 5.6
11500 4.8 40.6 227 6 3 7.8 4.3 | 5.0 41.0 201 4 2 10.1 5.5
11250 5.4 41.7 236 6 3 7.7 4.2 | 5.8 42.4 201 4 2 10.2 5.6
11000 6.0 42.8 245 6 3 8.3 4.6 | 6.6 43.9 201 4 2 9.9 5.4
10750 6.6 43.9 247 6 3 8.9 4.9 | 7.3 45.1 200 4 2 9.7 5.3
10500 7.3 45.1 250 6 3 8.7 4.8 | 8.0 46.4 199 4 2 9.7 5.3
10250 7.9 46.2 253 5 3 8.7 4.8 | 8.7 47.7 198 4 2 9.7 5.3
10000 8.6 47.5 256 5 3 8.9 4.9 | 9.5 49.1 197 4 2 9.9 5.4
9750 9.9 49.8 269 5 3 9.1 5.0 | 11.0 51.8 196 4 2 10.0 5.5
9500 10.6 51.1 275 5 3 9.1 5.0 | 11.7 53.1 195 4 2 10.0 5.5
9250 11.3 52.3 282 6 3 7.8 4.3 | 12.5 54.5 194 4 2 10.0 5.5
9000 11.8 53.2 289 7 4 7.0 3.8 | 13.2 55.8 193 3 2 10.1 5.5
8750 12.3 54.1 294 9 4 6.8 3.7 | 14.0 57.2 191 3 2 9.8 5.4
8500 12.8 55.0 297 10 5 8.4 4.6 | 14.7 58.5 189 3 2 10.9 6.0
8250 13.5 56.3 298 11 5 13.7 7.5 | 15.7 60.3 185 3 2 17.7 9.7
8000 14.7 58.5 297 9 5 17.6 9.6 | 17.3 63.1 179 3 2 25.5 14.0
7750 15.8 60.4 295 8 4 12.4 6.8 | 18.9 66.0 172 3 2 12.9 7.1
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
05/18/2013 at 1500 MDT | 05/18/2013 at 1800 MDT
|
K index... +21.5 | K index... +24.1
|
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 -55.9 -68.6 244 14 7 2.6 1.4 | -55.4 -67.7 251 11 6 2.9 1.6
45000 -52.5 -62.5 237 18 9 -1.2 -0.7 | -51.5 -60.7 237 14 7 -0.5 -0.3
40000 -54.3 -65.7 211 43 22 -1.1 -0.6 | -52.1 -61.8 224 29 15 -0.4 -0.2
38000 -53.8 -64.8 206 48 24 1.5 0.8 | -52.2 -62.0 215 34 18 -0.2 -0.1
36000 -52.9 -63.2 201 51 26 1.5 0.8 | -52.4 -62.3 205 40 21 -0.2 -0.1
34000 -50.7 -59.3 198 54 28 7.3 4.0 | -51.2 -60.2 200 44 23 6.3 3.5
32000 -46.4 -51.5 198 54 28 7.3 4.0 | -47.4 -53.3 203 40 21 6.4 3.5
30000 -41.9 -43.4 200 53 27 8.2 4.5 | -43.1 -45.6 206 36 18 9.0 4.9
29000 -39.4 -38.9 203 51 26 8.2 4.5 | -40.4 -40.7 209 33 17 9.0 4.9
28000 -36.9 -34.4 207 49 25 8.2 4.5 | -37.7 -35.9 211 30 16 9.0 4.9
27000 -34.5 -30.1 210 47 24 8.2 4.5 | -34.4 -29.9 214 26 14 8.3 4.6
26000 -31.4 -24.5 213 44 23 8.2 4.5 | -31.9 -25.4 215 21 11 8.4 4.6
25000 -29.0 -20.2 215 41 21 8.2 4.5 | -29.4 -20.9 216 17 9 8.4 4.6
24000 -26.6 -15.9 216 38 19 7.4 4.1 | -27.0 -16.6 217 12 6 7.5 4.1
23000 -24.3 -11.7 216 32 17 7.5 4.1 | -24.7 -12.5 216 10 5 7.7 4.2
22000 -22.1 -7.8 216 26 14 7.5 4.1 | -22.4 -8.3 215 8 4 7.7 4.2
21000 -19.9 -3.8 213 22 11 7.4 4.0 | -20.2 -4.4 214 6 3 7.2 4.0
20000 -17.7 0.1 202 19 10 7.4 4.1 | -18.1 -0.6 211 5 3 7.3 4.0
19500 -16.6 2.1 195 17 9 7.4 4.1 | -17.0 1.4 209 4 2 7.3 4.0
19000 -15.6 3.9 187 16 8 7.4 4.1 | -15.9 3.4 206 4 2 7.3 4.0
18500 -14.4 6.1 183 15 8 7.8 4.3 | -14.8 5.4 217 3 2 7.7 4.2
18000 -13.3 8.1 180 14 7 7.7 4.2 | -13.7 7.3 237 4 2 7.7 4.2
17500 -12.1 10.2 176 13 7 8.5 4.7 | -12.6 9.3 252 4 2 8.0 4.4
17000 -10.8 12.6 176 12 6 8.8 4.9 | -11.4 11.5 259 5 3 8.2 4.5
16500 -9.5 14.9 176 10 5 9.1 5.0 | -10.2 13.6 265 6 3 8.5 4.6
16000 -8.1 17.4 177 10 5 9.9 5.4 | -8.8 16.2 267 6 3 9.9 5.4
15500 -6.6 20.1 179 9 5 9.9 5.4 | -7.3 18.9 268 6 3 9.8 5.3
15000 -5.2 22.6 181 9 5 9.8 5.4 | -5.8 21.6 269 6 3 10.5 5.8
14500 -3.7 25.3 182 8 4 9.8 5.4 | -4.2 24.4 270 6 3 10.5 5.8
14000 -2.2 28.0 184 8 4 9.9 5.4 | -2.7 27.1 271 6 3 10.2 5.6
13500 -0.7 30.7 186 7 4 9.9 5.4 | -1.1 30.0 272 6 3 10.1 5.6
13000 0.7 33.3 189 7 4 9.8 5.4 | 0.4 32.7 272 6 3 9.9 5.4
12500 2.2 36.0 191 7 3 9.8 5.4 | 1.8 35.2 274 6 3 9.7 5.3
12000 3.7 38.7 194 7 3 9.8 5.4 | 3.3 37.9 275 6 3 9.9 5.4
11750 4.4 39.9 195 7 3 9.8 5.4 | 4.0 39.2 276 6 3 10.2 5.6
11500 5.1 41.2 196 6 3 9.8 5.4 | 4.8 40.6 276 6 3 10.1 5.6
11250 5.8 42.4 197 6 3 9.7 5.3 | 5.6 42.1 277 6 3 10.2 5.6
11000 6.6 43.9 198 6 3 9.8 5.4 | 6.3 43.3 278 6 3 10.0 5.5
10750 7.3 45.1 198 6 3 10.0 5.5 | 7.0 44.6 279 6 3 9.7 5.3
10500 8.1 46.6 198 6 3 10.0 5.5 | 7.8 46.0 280 6 3 9.7 5.3
10250 8.8 47.8 198 6 3 10.0 5.5 | 8.5 47.3 281 6 3 9.6 5.3
10000 10.3 50.5 198 6 3 9.9 5.4 | 10.0 50.0 283 6 3 10.2 5.6
9750 11.0 51.8 197 6 3 9.9 5.4 | 10.7 51.3 284 6 3 10.2 5.6
9500 11.8 53.2 197 6 3 9.9 5.4 | 11.5 52.7 285 6 3 10.3 5.6
9250 12.5 54.5 197 6 3 9.8 5.4 | 12.2 54.0 286 6 3 9.9 5.5
9000 13.2 55.8 196 6 3 9.7 5.3 | 13.0 55.4 288 6 3 9.5 5.2
8750 14.0 57.2 196 6 3 9.8 5.4 | 13.7 56.7 289 6 3 9.6 5.3
8500 14.7 58.5 195 6 3 9.5 5.2 | 14.4 57.9 291 6 3 9.5 5.2
8250 15.5 59.9 195 6 3 14.8 8.1 | 15.1 59.2 293 6 3 10.5 5.8
8000 16.9 62.4 197 4 2 24.6 13.5 | 15.9 60.6 296 5 3 12.6 6.9
7750 18.4 65.1 200 3 2 7.2 4.0 | 16.7 62.1 300 4 2 9.1 5.0
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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