Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
550
UXUS97 KBOU 230113
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1812 MST Saturday, February 22, 2025
This forecast is for Sunday, February 23, 2025:
If the trigger temperature of 54.0 F/12.2 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 559 ft/min (2.8 m/s)
Maximum height of thermals.................. 12461 ft MSL (7145 ft AGL)
Forecast maximum temperature................... 60.0 F/16.0 C
Time of trigger temperature.................... 1130 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................. 9702 ft MSL (4386 ft AGL)
Thermal soaring outlook for Monday 02/24....... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1700 MST).........
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1700 MST)................ Neither
Potential height of wave....................... 18381 ft MSL (13065 ft AGL)
Wave soaring outlook for Monday 02/24.......... Poor
Remarks...
Sunrise/Sunset.................... 06:40:25 / 17:45:04 MST
Total possible sunshine........... 11 hr 4 min 39 sec (664 min 39 sec)
Altitude of sun at 12:12:44 MST... 40.62 degrees
Upper air data from numerical model forecast valid on 02/23/2025 at 0500 MST
Freezing level.................. 5354 ft MSL (38 ft AGL)
Additional freezing level....... 9393 ft MSL (4077 ft AGL)
Convective condensation level... 16576 ft MSL (11260 ft AGL)
Lifted condensation level....... 15575 ft MSL (10258 ft AGL)
Lifted index.................... +1.7
K index......................... +4.7
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 -56.9 -70.4 330 34 18 0.8 0.4 M M M M M
45000 -55.7 -68.3 330 43 22 0.9 0.5 M M M M M
40000 -54.3 -65.7 320 44 23 1.0 0.5 M M M M M
38000 -53.9 -65.0 325 45 23 -0.0 -0.0 M M M M M
36000 -54.0 -65.2 350 51 26 -0.0 -0.0 M M M M M
34000 -53.3 -63.9 005 59 31 7.4 4.1 M M M M M
32000 -49.1 -56.4 005 60 31 6.9 3.8 M M M M M
30000 -45.0 -49.0 005 58 30 6.2 3.4 31.3 88.3 11.8 M M
29000 -43.2 -45.8 360 52 27 6.2 3.4 29.8 85.6 10.8 M M
28000 -41.3 -42.3 355 46 23 6.2 3.4 28.4 83.1 9.9 M M
27000 -39.5 -39.1 350 40 21 6.1 3.4 27.2 80.9 9.0 M M
26000 -37.7 -35.9 340 36 19 6.0 3.3 25.6 78.1 7.9 M M
25000 -35.9 -32.6 335 33 17 6.0 3.3 24.2 75.5 6.9 M M
24000 -34.1 -29.4 330 30 16 6.2 3.4 22.9 73.2 5.9 M M
23000 -31.7 -25.1 325 29 15 8.4 4.6 22.2 71.9 5.4 M M
22000 -29.2 -20.6 325 27 14 8.4 4.6 21.6 71.0 5.0 M M
21000 -26.6 -15.9 325 26 13 8.3 4.6 21.2 70.2 4.7 M M
20000 -24.2 -11.6 325 28 15 8.3 4.6 20.6 69.2 4.3 M M
19500 -22.9 -9.2 325 29 15 8.3 4.6 20.4 68.7 4.1 M M
19000 -21.7 -7.1 325 31 16 8.3 4.6 20.2 68.3 3.9 M M
18500 -19.8 -3.6 325 32 16 7.8 4.3 19.8 67.6 3.6 M M
18000 -18.7 -1.7 325 32 17 7.9 4.3 19.5 67.0 3.3 M M
17500 -17.5 0.5 325 33 17 8.1 4.4 19.2 66.5 3.1 M M
17000 -16.3 2.7 330 32 17 8.2 4.5 18.9 66.0 2.8 M M
16500 -15.0 5.0 330 32 17 8.3 4.6 18.6 65.6 2.6 M M
16000 -13.8 7.2 330 32 16 8.6 4.7 18.4 65.1 2.4 M M
15500 -12.5 9.5 330 32 16 8.7 4.8 18.2 64.8 2.3 M M
15000 -11.3 11.7 330 32 16 7.5 4.1 17.9 64.3 2.0 M M
14500 -10.2 13.6 330 31 16 7.6 4.2 17.6 63.6 1.7 M M
14000 -9.1 15.6 335 31 16 7.2 3.9 17.2 63.0 1.3 M M
13500 -8.0 17.6 335 30 16 7.2 3.9 16.8 62.2 0.9 M M
13000 -7.0 19.4 335 30 15 6.8 3.7 16.3 61.4 0.5 M M
12500 -6.0 21.2 340 29 15 6.7 3.7 15.8 60.5 0.0 M M
12000 -5.0 23.0 340 27 14 6.2 3.4 15.3 59.6 -0.5 516 2.6
11500 -4.1 24.6 345 25 13 6.0 3.3 14.7 58.5 -1.1 474 2.4
11000 -3.2 26.2 345 23 12 6.9 3.8 14.1 57.5 -1.6 432 2.2
10500 -2.1 28.2 345 21 11 7.8 4.3 13.7 56.7 -2.0 385 2.0
10250 -1.6 29.1 345 20 10 4.7 2.6 13.5 56.4 -2.2 361 1.8
10000 -1.4 29.5 350 20 10 4.1 2.3 13.0 55.4 -2.7 347 1.8
9750 -0.9 30.4 345 18 9 7.9 4.4 12.8 55.0 -3.0 325 1.6
9500 -0.3 31.5 345 16 8 8.4 4.6 12.6 54.7 -3.1 299 1.5
9250 0.3 32.5 345 14 7 7.3 4.0 12.5 54.5 -3.2 274 1.4
9000 0.8 33.4 345 12 6 6.4 3.5 12.3 54.1 -3.5 252 1.3
8750 1.3 34.3 340 11 5 8.0 4.4 12.0 53.7 -3.7 228 1.2
8500 2.0 35.6 335 10 5 8.7 4.8 12.0 53.5 -3.8 202 1.0
8250 2.7 36.9 335 9 5 9.4 5.1 11.9 53.4 -3.9 174 0.9
8000 3.4 38.1 330 11 6 9.7 5.3 11.9 53.4 -3.9 145 0.7
7750 4.1 39.4 330 13 7 10.5 5.8 11.9 53.4 -3.9 115 0.6
7500 4.8 40.6 325 16 8 5.2 2.8 11.9 53.3 -3.9 87 0.4
7250 4.8 40.6 320 17 9 -4.2 -2.3 11.1 51.9 -4.7 81 0.4
7000 4.3 39.7 305 20 10 -5.5 -3.0 9.9 49.8 -5.9 87 0.4
6750 3.9 39.0 295 22 11 -6.7 -3.7 8.8 47.8 -7.1 93 0.5
6500 3.3 37.9 290 25 13 -8.1 -4.5 7.4 45.3 -8.5 104 0.5
6250 2.7 36.9 285 21 11 -7.3 -4.0 6.1 42.9 -9.8 114 0.6
6000 2.1 35.8 280 18 9 -7.6 -4.2 4.8 40.6 -11.2 124 0.6
5750 1.5 34.7 265 15 8 -7.2 -4.0 3.5 38.3 -12.5 135 0.7
5500 0.9 33.6 255 10 5 -9.2 -5.1 2.2 35.9 -13.9 145 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
02/23/2025 at 0800 MST | 02/23/2025 at 1100 MST
|
CAPE... 0.0 LI... +5.9 | CAPE... 0.0 LI... +9.6
CINH... 0.0 K Index... -7.9 | CINH... 0.0 K Index... -26.0
|
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 -56.9 -70.4 335 41 21 1.3 0.7 | -55.5 -67.9 325 43 22 2.2 1.2
45000 -55.0 -67.0 330 51 27 0.5 0.3 | -52.5 -62.5 335 51 26 -3.7 -2.0
40000 -57.0 -70.6 335 59 30 -1.3 -0.7 | -58.7 -73.7 330 64 33 -4.1 -2.3
38000 -57.0 -70.6 345 61 31 1.3 0.7 | -59.0 -74.2 335 64 33 2.8 1.5
36000 -56.2 -69.2 005 67 35 1.3 0.7 | -57.3 -71.1 350 62 32 2.8 1.5
34000 -54.8 -66.6 015 76 39 7.6 4.2 | -54.3 -65.7 360 64 33 8.4 4.6
32000 -50.5 -58.9 010 72 37 7.2 4.0 | -49.2 -56.6 360 63 32 8.5 4.6
30000 -45.1 -49.2 010 68 35 9.6 5.3 | -44.2 -47.6 005 59 30 8.1 4.4
29000 -42.2 -44.0 015 67 34 9.6 5.3 | -41.8 -43.2 360 54 28 8.1 4.4
28000 -39.4 -38.9 015 66 34 9.6 5.3 | -39.4 -38.9 360 49 25 8.1 4.4
27000 -36.5 -33.7 015 64 33 8.8 4.8 | -36.9 -34.4 360 43 22 9.2 5.0
26000 -33.9 -29.0 015 59 30 8.7 4.8 | -34.2 -29.6 360 37 19 9.1 5.0
25000 -31.3 -24.3 015 54 28 8.7 4.8 | -31.4 -24.5 360 30 16 9.1 5.0
24000 -28.7 -19.7 010 48 25 7.4 4.1 | -28.7 -19.7 355 25 13 9.1 5.0
23000 -26.8 -16.2 360 45 23 6.5 3.6 | -26.0 -14.8 350 26 13 9.0 5.0
22000 -24.8 -12.6 350 44 23 6.5 3.6 | -23.3 -9.9 345 27 14 9.0 5.0
21000 -22.8 -9.0 340 44 22 6.9 3.8 | -20.5 -4.9 340 29 15 9.2 5.0
20000 -20.8 -5.4 345 43 22 6.9 3.8 | -17.8 -0.0 335 32 16 9.1 5.0
19500 -19.8 -3.6 345 43 22 6.9 3.8 | -16.4 2.5 335 33 17 9.2 5.0
19000 -18.7 -1.7 345 42 22 6.9 3.8 | -15.0 5.0 335 35 18 9.3 5.1
18500 -17.7 0.1 345 41 21 5.8 3.2 | -13.7 7.3 335 35 18 7.5 4.1
18000 -16.9 1.6 345 39 20 5.5 3.0 | -12.1 10.2 340 32 17 7.4 4.1
17500 -16.1 3.0 340 36 19 5.6 3.1 | -11.1 12.0 345 31 16 5.4 2.9
17000 -15.2 4.6 340 34 18 6.3 3.4 | -10.4 13.3 345 30 15 5.1 2.8
16500 -14.3 6.3 340 32 17 6.2 3.4 | -9.6 14.7 345 29 15 4.5 2.4
16000 -13.4 7.9 340 31 16 6.6 3.6 | -9.0 15.8 340 28 15 3.5 1.9
15500 -11.9 10.6 340 28 14 6.6 3.6 | -8.5 16.7 335 28 14 3.5 1.9
15000 -10.9 12.4 340 26 14 6.5 3.6 | -7.9 17.8 335 26 14 4.5 2.5
14500 -10.0 14.0 340 25 13 6.4 3.5 | -7.3 18.9 330 25 13 4.3 2.4
14000 -8.9 16.0 340 24 12 7.8 4.3 | -6.6 20.1 330 23 12 5.5 3.0
13500 -7.8 18.0 340 23 12 7.8 4.3 | -5.8 21.6 330 21 11 5.4 3.0
13000 -6.7 19.9 340 23 12 6.8 3.7 | -5.0 23.0 325 19 10 5.8 3.2
12500 -5.7 21.7 340 22 11 6.7 3.7 | -4.1 24.6 325 16 8 5.9 3.2
12000 -4.7 23.5 340 20 10 7.5 4.1 | -3.2 26.2 325 14 7 6.2 3.4
11500 -3.6 25.5 340 19 10 7.6 4.2 | -2.3 27.9 320 12 6 6.3 3.4
11000 -2.5 27.5 340 17 9 7.4 4.1 | -1.4 29.5 310 10 5 6.8 3.7
10500 -1.4 29.5 340 15 8 8.3 4.6 | -0.3 31.5 300 8 4 7.4 4.1
10250 -0.8 30.6 340 14 7 3.7 2.0 | 0.2 32.4 295 7 4 4.8 2.6
10000 -0.7 30.7 340 14 7 3.6 2.0 | 0.4 32.7 290 7 4 4.9 2.7
9750 -0.2 31.6 335 12 6 8.6 4.7 | 1.0 33.8 275 7 3 7.5 4.1
9500 0.4 32.7 325 11 5 8.1 4.4 | 1.5 34.7 260 7 3 7.0 3.9
9250 1.0 33.8 315 9 5 7.0 3.8 | 2.0 35.6 250 7 4 6.4 3.5
9000 1.5 34.7 310 9 4 6.5 3.6 | 2.4 36.3 245 8 4 6.4 3.5
8750 2.1 35.8 305 8 4 9.3 5.1 | 3.0 37.4 240 8 4 8.1 4.4
8500 2.8 37.0 300 8 4 10.1 5.5 | 3.6 38.5 235 8 4 8.6 4.7
8250 3.5 38.3 300 8 4 9.7 5.3 | 4.3 39.7 235 8 4 9.8 5.4
8000 4.3 39.7 305 9 4 9.3 5.1 | 5.1 41.2 240 8 4 10.4 5.7
7750 5.0 41.0 310 9 5 10.5 5.8 | 5.8 42.4 245 8 4 9.8 5.4
7500 5.7 42.3 315 11 5 6.2 3.4 | 6.5 43.7 260 8 4 6.3 3.5
7250 5.8 42.4 305 13 7 0.2 0.1 | 6.7 44.1 270 9 5 1.7 0.9
7000 5.8 42.4 300 17 9 0.7 0.4 | 6.8 44.2 280 12 6 1.9 1.1
6750 5.9 42.6 295 21 11 -0.6 -0.3 | 6.8 44.2 285 15 8 -1.4 -0.8
6500 5.5 41.9 290 23 12 -10.5 -5.8 | 6.5 43.7 280 19 10 -3.1 -1.7
6250 4.3 39.7 285 20 10 -16.7 -9.1 | 6.4 43.5 275 16 8 -0.5 -0.3
6000 3.2 37.8 275 18 9 -14.8 -8.1 | 6.2 43.2 270 13 7 -1.8 -1.0
5750 2.0 35.6 265 17 9 -15.9 -8.7 | 6.1 43.0 260 10 5 1.2 0.7
5500 0.7 33.3 255 11 6 -16.2 -8.9 | 6.4 43.5 250 8 4 9.7 5.3
02/23/2025 at 1400 MST | 02/23/2025 at 1700 MST
|
CAPE... 0.0 LI... +7.9 | CAPE... 0.0 LI... +5.9
CINH... 0.0 K Index... -11.9 | CINH... 0.0 K Index... +2.6
|
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 -56.6 -69.9 325 50 26 2.9 1.6 | -57.1 -70.8 325 54 28 3.3 1.8
45000 -52.7 -62.9 330 63 33 -4.8 -2.6 | -52.5 -62.5 330 66 34 -3.5 -1.9
40000 -59.8 -75.6 325 56 29 -4.7 -2.6 | -58.4 -73.1 330 46 24 -3.7 -2.0
38000 -59.2 -74.6 330 54 28 5.1 2.8 | -57.9 -72.2 325 44 23 3.0 1.7
36000 -55.8 -68.4 330 53 27 5.1 2.8 | -56.1 -69.0 325 45 23 3.0 1.7
34000 -52.3 -62.1 335 51 26 7.1 3.9 | -53.2 -63.8 320 44 23 8.5 4.7
32000 -48.0 -54.4 335 48 25 7.1 3.9 | -48.1 -54.6 320 41 21 8.6 4.7
30000 -43.3 -45.9 335 43 22 8.9 4.9 | -42.8 -45.0 320 38 20 9.2 5.0
29000 -40.6 -41.1 335 40 20 8.9 4.9 | -39.4 -38.9 315 37 19 9.2 5.0
28000 -38.0 -36.4 335 36 19 8.9 4.9 | -36.7 -34.1 310 37 19 9.2 5.0
27000 -35.3 -31.5 335 33 17 8.6 4.7 | -33.9 -29.0 310 36 19 9.3 5.1
26000 -32.7 -26.9 330 32 16 8.6 4.7 | -31.1 -24.0 305 36 18 9.3 5.1
25000 -30.1 -22.2 325 30 15 8.6 4.7 | -28.4 -19.1 305 35 18 9.3 5.1
24000 -27.5 -17.5 320 29 15 9.1 5.0 | -25.7 -14.3 300 34 17 8.1 4.4
23000 -24.8 -12.6 320 26 14 9.2 5.0 | -23.2 -9.8 300 32 17 8.2 4.5
22000 -22.0 -7.6 320 24 13 9.2 5.0 | -20.8 -5.4 295 31 16 8.2 4.5
21000 -19.3 -2.7 315 23 12 8.3 4.6 | -18.4 -1.1 290 29 15 6.9 3.8
20000 -16.8 1.8 315 22 11 8.4 4.6 | -16.3 2.7 285 27 14 7.0 3.8
19500 -15.5 4.1 310 21 11 8.4 4.6 | -15.3 4.5 285 27 14 7.0 3.8
19000 -14.2 6.4 310 21 11 8.5 4.7 | -14.3 6.3 280 26 13 7.0 3.8
18500 -13.0 8.6 305 20 10 7.4 4.0 | -13.2 8.2 280 25 13 6.7 3.7
18000 -11.4 11.5 300 18 9 7.3 4.0 | -12.2 10.0 280 24 13 6.8 3.7
17500 -10.4 13.3 300 17 9 6.6 3.6 | -11.2 11.8 285 24 12 7.1 3.9
17000 -9.4 15.1 300 18 9 6.5 3.6 | -10.2 13.6 285 24 12 7.5 4.1
16500 -8.4 16.9 300 19 10 6.1 3.4 | -9.1 15.6 290 24 12 7.6 4.2
16000 -7.6 18.3 305 21 11 5.6 3.1 | -8.0 17.6 295 24 12 6.6 3.6
15500 -6.8 19.8 305 24 12 5.6 3.1 | -6.5 20.3 300 24 12 6.7 3.7
15000 -6.0 21.2 310 24 12 5.2 2.8 | -5.6 21.9 300 24 12 6.4 3.5
14500 -5.2 22.6 310 24 12 5.2 2.8 | -4.7 23.5 305 24 12 6.5 3.6
14000 -4.4 24.1 310 23 12 5.7 3.2 | -3.7 25.3 305 24 12 6.0 3.3
13500 -3.6 25.5 310 22 11 5.7 3.1 | -2.9 26.8 305 24 12 6.0 3.3
13000 -2.7 27.1 310 20 11 5.6 3.1 | -2.0 28.4 305 24 12 5.9 3.2
12500 -1.9 28.6 305 19 10 5.6 3.1 | -1.1 30.0 305 24 12 5.9 3.2
12000 -1.0 30.2 305 18 9 5.3 2.9 | -0.3 31.5 305 23 12 5.2 2.8
11500 -0.3 31.5 300 16 8 5.2 2.9 | 0.5 32.9 305 20 10 4.9 2.7
11000 0.5 32.9 290 14 7 5.1 2.8 | 1.3 34.3 300 18 9 6.9 3.8
10500 1.2 34.2 285 14 7 5.7 3.1 | 2.4 36.3 305 17 9 8.0 4.4
10250 1.6 34.9 280 13 7 2.7 1.5 | 2.9 37.2 305 16 8 4.7 2.6
10000 1.8 35.2 275 13 7 4.6 2.5 | 3.2 37.8 305 17 9 5.8 3.2
9750 2.4 36.3 270 13 7 9.1 5.0 | 3.9 39.0 305 17 9 10.1 5.5
9500 3.0 37.4 265 13 7 7.9 4.3 | 4.5 40.1 305 17 9 8.9 4.9
9250 3.6 38.5 260 13 7 8.2 4.5 | 5.2 41.4 305 17 9 9.4 5.2
9000 4.2 39.6 260 13 7 8.5 4.7 | 5.8 42.4 300 19 10 6.8 3.7
8750 4.8 40.6 265 13 7 9.0 5.0 | 6.2 43.2 300 22 11 4.0 2.2
8500 5.5 41.9 265 14 7 9.5 5.2 | 6.5 43.7 295 25 13 4.1 2.3
8250 6.2 43.2 270 15 8 6.9 3.8 | 6.8 44.2 290 29 15 3.4 1.9
8000 6.5 43.7 275 18 9 4.5 2.5 | 7.0 44.6 285 30 16 2.9 1.6
7750 6.8 44.2 280 21 11 3.7 2.0 | 7.2 45.0 285 31 16 3.3 1.8
7500 7.0 44.6 285 23 12 2.8 1.6 | 7.5 45.5 280 30 15 4.1 2.2
7250 7.2 45.0 285 23 12 3.8 2.1 | 7.8 46.0 280 28 15 6.0 3.3
7000 7.4 45.3 280 21 11 3.6 2.0 | 8.3 46.9 280 25 13 6.9 3.8
6750 7.7 45.9 280 19 10 5.5 3.0 | 8.8 47.8 280 22 11 7.1 3.9
6500 8.2 46.8 280 16 8 7.5 4.1 | 9.3 48.7 280 20 10 6.2 3.4
6250 8.7 47.7 280 14 7 7.3 4.0 | 9.7 49.5 280 17 9 4.7 2.6
6000 9.2 48.6 275 11 6 7.2 4.0 | 10.0 50.0 280 13 7 5.5 3.0
5750 9.7 49.5 275 9 5 7.8 4.3 | 10.4 50.7 280 10 5 3.5 1.9
5500 10.3 50.5 275 8 4 10.9 6.0 | 10.3 50.5 275 6 3 -2.6 -1.4
________________________________________________________________________________
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.
042613