Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
766
UXUS97 KBOU 130159
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1859 MST Wednesday, February 12, 2025
This forecast is for Thursday, February 13, 2025:
If the trigger temperature of 34.2 F/1.2 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 390 ft/min (2.0 m/s)
Maximum height of thermals.................. 10744 ft MSL (5430 ft AGL)
Forecast maximum temperature................... 38.0 F/3.8 C
Time of trigger temperature.................... 1230 MST
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................. 8772 ft MSL (3459 ft AGL)
Thermal soaring outlook for Friday 02/14....... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1700 MST)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1700 MST)................ Neither
Potential height of wave....................... 33390 ft MSL (28076 ft AGL)
Wave soaring outlook for Friday 02/14.......... Fair
Remarks...
Sunrise/Sunset.................... 06:53:43 / 17:33:36 MST
Total possible sunshine........... 10 hr 39 min 53 sec (639 min 53 sec)
Altitude of sun at 12:13:40 MST... 37.06 degrees
Upper air data from numerical model forecast valid on 02/13/2025 at 0500 MST
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 21370 ft MSL (16056 ft AGL)
Lifted condensation level....... 16700 ft MSL (11386 ft AGL)
Lifted index.................... +11.8
K index......................... -38.2
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 -55.3 -67.5 275 54 28 1.2 0.7 M M M M M
45000 -53.4 -64.1 280 62 32 1.2 0.7 M M M M M
40000 -52.7 -62.9 280 70 36 0.3 0.2 M M M M M
38000 -52.6 -62.7 280 73 37 -0.6 -0.3 M M M M M
36000 -54.2 -65.6 290 76 39 -2.8 -1.5 M M M M M
34000 -56.1 -69.0 295 81 42 -2.7 -1.5 M M M M M
32000 -54.7 -66.5 295 82 42 4.3 2.4 M M M M M
30000 -52.1 -61.8 295 82 42 4.4 2.4 M M M M M
29000 -50.1 -58.2 300 81 42 8.2 4.5 23.2 73.7 14.9 M M
28000 -47.7 -53.9 300 81 41 8.3 4.5 22.5 72.5 14.6 M M
27000 -45.2 -49.4 300 80 41 8.3 4.5 22.0 71.6 14.4 M M
26000 -42.7 -44.9 300 79 41 7.7 4.2 21.5 70.6 14.2 M M
25000 -40.5 -40.9 300 77 40 7.6 4.2 20.5 69.0 13.6 M M
24000 -38.2 -36.8 300 75 38 7.6 4.2 19.7 67.5 13.2 M M
23000 -35.9 -32.6 300 72 37 6.8 3.7 19.0 66.2 12.7 M M
22000 -34.0 -29.2 300 68 35 6.6 3.6 17.7 63.9 11.8 M M
21000 -32.0 -25.6 300 64 33 6.6 3.6 16.6 61.9 11.1 M M
20000 -30.0 -22.0 305 60 31 6.4 3.5 15.5 59.9 10.2 M M
19500 -29.1 -20.4 305 57 30 6.4 3.5 14.9 58.8 9.8 M M
19000 -28.1 -18.6 305 55 28 6.4 3.5 14.3 57.7 9.3 M M
18500 -27.1 -16.8 305 53 27 6.4 3.5 13.7 56.7 8.9 M M
18000 -26.2 -15.2 305 51 26 6.4 3.5 13.2 55.7 8.5 M M
17500 -24.7 -12.5 305 49 25 6.5 3.6 12.3 54.2 7.8 M M
17000 -23.7 -10.7 305 47 24 6.5 3.5 11.8 53.2 7.4 M M
16500 -22.8 -9.0 305 46 24 6.2 3.4 11.2 52.1 6.9 M M
16000 -21.9 -7.4 305 45 23 6.2 3.4 10.6 51.0 6.4 M M
15500 -21.0 -5.8 305 44 23 5.8 3.2 9.9 49.9 5.9 M M
15000 -20.1 -4.2 305 43 22 5.9 3.2 9.3 48.7 5.3 M M
14500 -19.2 -2.6 305 42 22 5.7 3.2 8.6 47.6 4.8 M M
14000 -18.3 -0.9 305 41 21 5.7 3.2 8.0 46.3 4.2 M M
13500 -17.5 0.5 305 40 20 5.7 3.1 7.3 45.2 3.6 M M
13000 -16.6 2.1 300 38 20 5.7 3.1 6.6 43.9 3.0 M M
12500 -15.8 3.6 300 36 19 4.9 2.7 5.9 42.7 2.4 M M
12000 -15.1 4.8 300 33 17 4.6 2.5 5.1 41.2 1.6 M M
11500 -14.4 6.1 295 30 16 5.4 3.0 4.3 39.8 0.9 M M
11000 -13.5 7.7 295 28 14 5.7 3.1 3.7 38.6 0.3 M M
10500 -12.7 9.1 295 25 13 4.8 2.6 3.0 37.3 -0.4 371 1.9
10250 -12.4 9.7 295 24 13 4.1 2.3 2.5 36.6 -0.8 353 1.8
10000 -12.1 10.2 290 23 12 6.2 3.4 2.1 35.9 -1.2 336 1.7
9750 -11.5 11.3 290 22 11 6.9 3.8 2.0 35.5 -1.3 312 1.6
9500 -11.1 12.0 290 21 11 4.4 2.4 1.6 34.9 -1.7 292 1.5
9250 -10.8 12.6 285 21 11 4.3 2.4 1.2 34.1 -2.1 275 1.4
9000 -10.5 13.1 285 20 10 3.8 2.1 0.7 33.3 -2.5 259 1.3
8750 -10.2 13.6 280 19 10 2.7 1.5 0.2 32.4 -3.0 244 1.2
8500 -10.1 13.8 280 18 9 2.4 1.3 -0.3 31.4 -3.6 231 1.2
8250 -9.9 14.2 275 17 9 3.1 1.7 -0.9 30.4 -4.1 218 1.1
8000 -9.7 14.5 270 15 8 1.2 0.7 -1.4 29.4 -4.7 205 1.0
7750 -9.7 14.5 265 14 7 -0.2 -0.1 -2.2 28.1 -5.5 198 1.0
7500 -9.7 14.5 260 12 6 0.9 0.5 -2.9 26.8 -6.2 190 1.0
7250 -9.6 14.7 250 10 5 0.8 0.4 -3.6 25.5 -6.9 181 0.9
7000 -9.6 14.7 240 9 5 -0.0 -0.0 -4.3 24.3 -7.6 173 0.9
6750 -9.6 14.7 230 8 4 0.2 0.1 -5.1 22.9 -8.4 166 0.8
6500 -9.6 14.7 215 7 4 0.8 0.4 -5.7 21.7 -9.1 158 0.8
6250 -9.6 14.7 205 7 4 -1.4 -0.7 -6.5 20.3 -9.9 151 0.8
6000 -9.8 14.4 200 7 3 -3.5 -1.9 -7.4 18.6 -10.8 150 0.8
5750 -10.0 14.0 195 6 3 -1.1 -0.6 -8.4 16.9 -11.8 149 0.8
5500 -10.4 13.3 190 6 3 -14.0 -7.7 -9.5 15.0 -12.9 152 0.8
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
02/13/2025 at 0800 MST | 02/13/2025 at 1100 MST
|
CAPE... 0.0 LI... +8.6 | CAPE... 0.0 LI... +8.7
CINH... -0.1 K Index... -42.4 | CINH... -0.1 K Index... -35.9
|
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 -56.1 -69.0 275 48 25 0.4 0.2 | -56.6 -69.9 275 50 26 0.7 0.4
45000 -55.4 -67.7 275 67 34 0.4 0.2 | -55.5 -67.9 270 70 36 0.7 0.4
40000 -56.4 -69.5 280 72 37 -0.9 -0.5 | -59.2 -74.6 275 73 37 -3.0 -1.6
38000 -56.9 -70.4 280 73 37 -0.7 -0.4 | -60.6 -77.1 280 73 38 1.8 1.0
36000 -57.2 -71.0 290 75 38 -0.6 -0.3 | -59.7 -75.5 295 78 40 1.5 0.8
34000 -57.6 -71.7 300 78 40 -0.9 -0.5 | -58.8 -73.8 305 87 45 0.7 0.4
32000 -54.5 -66.1 300 79 41 6.5 3.6 | -54.4 -65.9 305 83 43 8.4 4.6
30000 -50.6 -59.1 300 80 41 6.3 3.5 | -49.3 -56.7 305 77 40 8.5 4.7
29000 -48.4 -55.1 300 78 40 7.8 4.3 | -46.1 -51.0 300 73 38 8.6 4.7
28000 -46.1 -51.0 295 75 38 7.7 4.3 | -43.6 -46.5 300 70 36 8.6 4.7
27000 -43.7 -46.7 295 72 37 7.7 4.3 | -41.0 -41.8 295 68 35 8.6 4.7
26000 -41.4 -42.5 295 69 35 7.4 4.1 | -38.6 -37.5 295 66 34 7.9 4.4
25000 -39.2 -38.6 290 65 34 7.5 4.1 | -36.2 -33.2 290 64 33 7.9 4.4
24000 -36.9 -34.4 290 62 32 7.5 4.1 | -33.8 -28.8 290 62 32 7.9 4.3
23000 -34.7 -30.5 290 58 30 8.0 4.4 | -31.6 -24.9 285 60 31 7.3 4.0
22000 -32.3 -26.1 290 55 28 7.9 4.3 | -29.4 -20.9 285 57 29 7.2 4.0
21000 -29.9 -21.8 290 52 27 7.9 4.3 | -27.2 -17.0 285 54 28 7.3 4.0
20000 -27.6 -17.7 290 49 25 7.4 4.1 | -25.1 -13.2 285 51 26 6.9 3.8
19500 -26.0 -14.8 290 47 24 7.4 4.0 | -24.1 -11.4 285 50 26 6.9 3.8
19000 -24.9 -12.8 295 46 24 7.4 4.1 | -23.0 -9.4 285 49 25 7.0 3.8
18500 -23.7 -10.7 295 45 23 7.4 4.1 | -22.0 -7.6 285 48 25 7.0 3.8
18000 -22.7 -8.9 295 44 23 6.8 3.7 | -21.0 -5.8 285 47 24 6.5 3.6
17500 -21.7 -7.1 295 44 23 6.8 3.7 | -20.0 -4.0 285 46 24 6.4 3.5
17000 -20.6 -5.1 295 44 22 6.5 3.6 | -19.0 -2.2 285 45 23 6.3 3.5
16500 -19.7 -3.5 295 43 22 6.3 3.5 | -18.1 -0.6 285 43 22 6.1 3.3
16000 -18.7 -1.7 295 42 22 6.3 3.5 | -16.7 1.9 285 42 21 5.8 3.2
15500 -17.8 -0.0 295 41 21 6.1 3.4 | -15.9 3.4 285 40 21 5.6 3.1
15000 -16.9 1.6 295 41 21 6.2 3.4 | -15.1 4.8 285 38 20 5.5 3.0
14500 -16.0 3.2 295 41 21 5.4 3.0 | -14.3 6.3 280 37 19 5.1 2.8
14000 -15.2 4.6 295 40 21 5.5 3.0 | -13.5 7.7 280 35 18 5.1 2.8
13500 -14.4 6.1 295 40 20 4.9 2.7 | -12.8 9.0 280 32 17 5.0 2.7
13000 -13.7 7.3 290 39 20 4.9 2.7 | -12.0 10.4 280 30 16 5.0 2.7
12500 -13.0 8.6 290 38 20 4.7 2.6 | -11.2 11.8 280 28 14 5.5 3.0
12000 -12.3 9.9 290 37 19 4.7 2.6 | -10.4 13.3 280 26 13 5.4 3.0
11500 -11.6 11.1 290 35 18 4.2 2.3 | -9.6 14.7 280 23 12 5.3 2.9
11000 -11.0 12.2 285 32 17 4.3 2.3 | -8.8 16.2 275 21 11 5.3 2.9
10500 -10.4 13.3 285 30 16 4.0 2.2 | -8.1 17.4 275 20 10 4.3 2.3
10250 -10.1 13.8 285 29 15 3.3 1.8 | -7.8 18.0 275 19 10 3.6 2.0
10000 -9.8 14.4 285 29 15 5.8 3.2 | -7.5 18.5 275 19 10 6.6 3.6
9750 -9.3 15.3 280 25 13 6.1 3.4 | -6.9 19.6 275 16 8 7.0 3.9
9500 -8.9 16.0 280 23 12 3.7 2.0 | -6.5 20.3 270 15 8 4.1 2.2
9250 -8.6 16.5 280 21 11 4.8 2.7 | -6.2 20.8 270 13 7 5.8 3.2
9000 -8.3 17.1 275 19 10 2.6 1.4 | -5.8 21.6 265 12 6 2.0 1.1
8750 -8.2 17.2 275 18 9 2.3 1.3 | -5.8 21.6 260 10 5 2.8 1.5
8500 -7.9 17.8 270 16 8 4.2 2.3 | -5.3 22.5 250 9 5 6.9 3.8
8250 -7.6 18.3 265 13 7 4.6 2.5 | -4.9 23.2 240 8 4 5.8 3.2
8000 -7.3 18.9 260 11 6 2.1 1.1 | -4.5 23.9 225 7 4 3.4 1.9
7750 -7.3 18.9 250 9 5 0.1 0.0 | -4.3 24.3 205 7 4 2.5 1.4
7500 -7.2 19.0 245 8 4 1.7 0.9 | -4.0 24.8 195 7 4 4.6 2.5
7250 -7.1 19.2 230 8 4 1.0 0.6 | -3.7 25.3 185 7 4 2.7 1.5
7000 -7.1 19.2 220 7 4 -0.5 -0.3 | -3.6 25.5 180 8 4 0.8 0.4
6750 -7.1 19.2 205 7 3 -0.2 -0.1 | -3.6 25.5 170 8 4 0.6 0.3
6500 -7.1 19.2 195 7 4 0.4 0.2 | -3.6 25.5 165 8 4 1.1 0.6
6250 -7.2 19.0 190 7 4 -3.6 -2.0 | -3.4 25.9 165 8 4 2.9 1.6
6000 -7.7 18.1 185 8 4 -7.2 -4.0 | -3.2 26.2 160 7 3 3.5 1.9
5750 -8.1 17.4 180 8 4 -3.2 -1.7 | -3.0 26.6 160 6 3 4.5 2.5
5500 -8.5 16.7 185 8 4 -12.6 -6.9 | -2.4 27.7 155 5 2 11.5 6.3
02/13/2025 at 1400 MST | 02/13/2025 at 1700 MST
|
CAPE... 0.0 LI... +10.4 | CAPE... 0.0 LI... +10.1
CINH... 0.0 K Index... -15.0 | CINH... 0.0 K Index... -2.8
|
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 -57.3 -71.1 270 59 30 0.1 0.1 | -58.6 -73.5 270 64 33 -0.6 -0.3
45000 -57.0 -70.6 265 75 38 0.0 0.0 | -59.5 -75.1 270 77 39 -0.6 -0.3
40000 -63.2 -81.8 275 72 37 -4.7 -2.6 | -62.8 -81.0 275 80 41 -2.4 -1.3
38000 -64.7 -84.5 280 72 37 5.1 2.8 | -63.0 -81.4 280 79 41 4.8 2.6
36000 -61.6 -78.9 290 73 38 5.2 2.8 | -60.0 -76.0 275 72 37 4.9 2.7
34000 -58.4 -73.1 295 75 39 5.8 3.2 | -57.1 -70.8 275 66 34 6.7 3.7
32000 -53.4 -64.1 290 71 37 8.7 4.8 | -51.3 -60.3 270 58 30 8.6 4.7
30000 -47.5 -53.5 290 67 35 9.4 5.1 | -46.1 -51.0 265 52 27 9.2 5.0
29000 -44.8 -48.6 285 66 34 9.1 5.0 | -43.4 -46.1 265 52 27 9.2 5.0
28000 -42.1 -43.8 285 64 33 9.1 5.0 | -40.6 -41.1 265 52 27 9.2 5.0
27000 -39.3 -38.7 285 63 32 9.1 5.0 | -37.9 -36.2 265 52 27 9.2 5.0
26000 -36.7 -34.1 285 61 32 8.9 4.9 | -35.2 -31.4 265 51 26 8.8 4.8
25000 -34.0 -29.2 285 60 31 8.9 4.9 | -32.6 -26.7 265 49 25 8.8 4.8
24000 -31.3 -24.3 285 59 30 9.0 4.9 | -29.9 -21.8 265 47 24 8.9 4.9
23000 -28.8 -19.8 280 58 30 8.5 4.7 | -27.4 -17.3 265 48 25 8.4 4.6
22000 -26.2 -15.2 280 57 29 8.5 4.7 | -24.9 -12.8 265 50 25 8.4 4.6
21000 -23.7 -10.7 280 56 29 8.5 4.7 | -22.4 -8.3 265 51 26 8.3 4.6
20000 -21.6 -6.9 280 56 29 7.0 3.8 | -20.1 -4.2 265 52 27 7.7 4.2
19500 -20.5 -4.9 280 56 29 7.0 3.9 | -19.0 -2.2 265 52 27 7.7 4.2
19000 -19.5 -3.1 280 55 29 7.1 3.9 | -17.8 -0.0 270 52 27 7.7 4.2
18500 -18.5 -1.3 280 55 28 7.3 4.0 | -16.7 1.9 270 52 27 7.9 4.3
18000 -17.6 0.3 280 55 28 5.1 2.8 | -15.6 3.9 270 52 27 6.4 3.5
17500 -16.8 1.8 280 53 28 5.1 2.8 | -14.2 6.4 270 50 26 6.8 3.7
17000 -16.0 3.2 280 52 27 4.6 2.5 | -13.3 8.1 270 50 26 4.8 2.6
16500 -15.5 4.1 280 50 26 3.8 2.1 | -12.6 9.3 270 49 25 5.0 2.7
16000 -14.6 5.7 275 48 25 3.7 2.0 | -11.9 10.6 270 47 24 4.1 2.2
15500 -14.0 6.8 275 45 23 3.6 2.0 | -11.3 11.7 270 44 23 3.7 2.0
15000 -13.5 7.7 270 42 22 3.8 2.1 | -10.8 12.6 265 40 21 3.9 2.1
14500 -12.8 9.0 270 39 20 4.2 2.3 | -10.1 13.8 265 37 19 4.2 2.3
14000 -12.2 10.0 270 35 18 4.4 2.4 | -9.5 14.9 260 34 17 4.2 2.3
13500 -11.4 11.5 265 32 16 5.4 3.0 | -8.9 16.0 260 30 16 3.8 2.1
13000 -10.6 12.9 265 29 15 5.4 2.9 | -8.3 17.1 260 27 14 3.9 2.1
12500 -9.8 14.4 260 26 13 6.0 3.3 | -7.6 18.3 255 23 12 4.8 2.7
12000 -8.9 16.0 255 23 12 5.9 3.3 | -6.9 19.6 250 19 10 4.7 2.6
11500 -7.9 17.8 250 19 10 6.3 3.4 | -6.0 21.2 245 16 8 6.2 3.4
11000 -7.0 19.4 245 16 8 6.2 3.4 | -5.1 22.8 230 13 7 6.1 3.3
10500 -6.2 20.8 235 14 7 5.3 2.9 | -4.2 24.4 220 12 6 6.3 3.5
10250 -5.8 21.6 230 13 7 4.5 2.5 | -3.7 25.3 215 12 6 5.5 3.0
10000 -5.4 22.3 220 12 6 8.0 4.4 | -3.3 26.1 210 12 6 8.5 4.6
9750 -4.6 23.7 215 11 6 8.5 4.6 | -2.5 27.5 200 12 6 8.6 4.7
9500 -4.2 24.4 205 11 6 5.2 2.8 | -2.1 28.2 195 12 6 5.7 3.1
9250 -3.7 25.3 200 10 5 6.3 3.4 | -1.6 29.1 190 11 6 6.7 3.7
9000 -3.3 26.1 190 10 5 5.2 2.8 | -1.1 30.0 185 11 6 5.6 3.1
8750 -2.9 26.8 180 10 5 5.4 3.0 | -0.8 30.6 180 11 6 3.6 2.0
8500 -2.4 27.7 175 10 5 6.3 3.5 | -0.6 30.9 175 11 6 2.8 1.5
8250 -2.0 28.4 170 10 5 6.2 3.4 | -0.3 31.5 175 10 5 3.5 1.9
8000 -1.5 29.3 165 11 5 4.8 2.6 | -0.1 31.8 170 10 5 1.4 0.8
7750 -1.2 29.8 155 10 5 4.1 2.2 | -0.2 31.6 170 9 5 -0.9 -0.5
7500 -0.9 30.4 155 10 5 5.1 2.8 | -0.2 31.6 165 8 4 -0.6 -0.3
7250 -0.6 30.9 155 10 5 4.0 2.2 | -0.3 31.5 165 7 4 -0.4 -0.2
7000 -0.4 31.3 150 9 5 1.7 0.9 | -0.3 31.5 160 6 3 0.6 0.4
6750 -0.3 31.5 140 8 4 4.0 2.2 | -0.3 31.5 155 5 3 0.9 0.5
6500 0.1 32.2 135 7 4 7.0 3.8 | -0.2 31.6 145 3 2 0.6 0.3
6250 0.5 32.9 130 6 3 8.1 4.4 | -0.2 31.6 115 2 1 1.6 0.9
6000 1.2 34.2 125 6 3 9.5 5.2 | -0.0 32.0 065 2 1 2.0 1.1
5750 1.8 35.2 120 5 3 8.4 4.6 | 0.1 32.2 030 3 2 2.9 1.6
5500 2.5 36.5 125 5 2 11.0 6.1 | 0.3 32.5 020 5 2 2.0 1.1
________________________________________________________________________________
This product is issued twice per day, once by approximately 0630 MST/0730 MDT
(1330 UTC) and again by approximately 1830 MST/1930 MDT (0130 UTC). It is not
continuously monitored nor updated after its initial issuance.
The information contained herein is based on rawinsonde observation and/or
numerical weather prediction model data taken near the old Stapleton
Airport site in Denver, Colorado at
North Latitude: 39 deg 46 min 5.016 sec
West Longitude: 104 deg 52 min 9.984 sec
Elevation: 5285 feet (1611 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.
DEFINITIONS:
CAPE (Convective Available Potential Energy) - An integrated measure of the
energy available for convective development, also known as the positive
area on a thermodynamic diagram. Units are Joules per kilogram. Larger
values are indicative of greater instability and the possibility of
stronger convective activity, including thunderstorms. Values around or
greater than 1000 suggest the possibility of severe weather should
convective activity develop.
CINH (Convective Inhibition) - An integrated measure of the amount of energy
needed to initiate convective activity, also known as the negative area on
a thermodynamic diagram. Units are Joules per kilogram. The more negative
this number, the more energy is required to initiate convection. This
inhibitive energy can be overcome through surface heating, cooling aloft,
lifting mechanisms (orographic, frontal, gravity waves, etc.)
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 (LI) - 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, cirrostratus, 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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