Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
808
UXUS97 KBOU 111253
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0652 MDT Wednesday, March 11, 2026
This forecast is for Wednesday, March 11, 2026:
If the trigger temperature of 39.5 F/4.2 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 663 ft/min (3.4 m/s)
Maximum height of thermals.................. 14191 ft MSL (8836 ft AGL)
Forecast maximum temperature................... 52.0 F/11.6 C
Time of trigger temperature.................... 1130 MDT
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................. 12378 ft MSL (7022 ft AGL)
Thermal soaring outlook for Thursday 03/12..... Good
Wave Soaring Index............................. Good
Wave Soaring Index trend (to 1800 MDT)......... Slight decrease
Height of stable layer (12-18K ft MSL)......... 17423 ft MSL (12068 ft AGL)
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 34661 ft MSL (29306 ft AGL)
Wave soaring outlook for Thursday 03/12........ Fair
Remarks...
Sunrise/Sunset.................... 07:16:38 / 19:02:07 MDT
Total possible sunshine........... 11 hr 45 min 28 sec (705 min 28 sec)
Altitude of sun at 13:09:23 MDT... 46.70 degrees
Upper air data from numerical model forecast valid on 03/11/2026 at 0600 MDT
Freezing level.................. 5648 ft MSL (293 ft AGL)
Convective condensation level... 11815 ft MSL (6460 ft AGL)
Lifted condensation level....... 13517 ft MSL (8161 ft AGL)
Lifted index.................... +10.1
K index......................... -6.2
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 -58.5 -73.3 265 49 25 -1.2 -0.7 M M M M M
45000 -60.3 -76.5 255 62 32 -1.2 -0.7 M M M M M
40000 -60.6 -77.1 295 89 46 -0.2 -0.1 M M M M M
38000 -59.0 -74.2 300 101 52 7.0 3.8 M M M M M
36000 -54.3 -65.7 305 105 54 6.9 3.8 M M M M M
34000 -50.1 -58.2 305 108 56 7.4 4.1 M M M M M
32000 -45.7 -50.3 305 104 54 7.4 4.0 M M M M M
30000 -41.3 -42.3 305 100 52 6.9 3.8 36.4 97.5 18.9 M M
29000 -39.2 -38.6 305 98 50 7.0 3.8 35.2 95.3 18.2 M M
28000 -37.1 -34.8 305 95 49 7.0 3.8 34.1 93.3 17.6 M M
27000 -35.0 -31.0 305 93 48 7.0 3.8 33.1 91.7 17.1 M M
26000 -33.0 -27.4 300 89 46 6.7 3.7 31.9 89.5 16.4 M M
25000 -31.0 -23.8 300 85 44 6.7 3.7 30.7 87.3 15.6 M M
24000 -29.0 -20.2 300 81 42 6.7 3.7 29.7 85.4 14.9 M M
23000 -26.9 -16.4 300 78 40 7.1 3.9 28.6 83.6 14.3 M M
22000 -24.8 -12.6 300 75 38 7.1 3.9 27.7 81.8 13.6 M M
21000 -22.6 -8.7 305 72 37 7.2 3.9 26.8 80.3 13.1 M M
20000 -20.9 -5.6 300 67 35 4.0 2.2 24.4 75.9 11.2 M M
19500 -20.3 -4.5 300 65 34 4.0 2.2 23.4 74.1 10.4 M M
19000 -19.7 -3.5 295 64 33 4.0 2.2 22.4 72.4 9.7 M M
18500 -19.1 -2.4 295 62 32 3.3 1.8 21.5 70.7 8.9 M M
18000 -18.7 -1.7 290 62 32 2.3 1.2 20.2 68.4 7.8 M M
17500 -18.4 -1.1 290 61 32 2.2 1.2 18.9 66.0 6.8 M M
17000 -18.1 -0.6 290 62 32 2.6 1.4 17.7 63.8 5.7 M M
16500 -17.7 0.1 285 62 32 2.6 1.4 16.4 61.6 4.6 M M
16000 -17.3 0.9 285 63 32 2.7 1.5 15.2 59.4 3.6 M M
15500 -16.9 1.6 285 61 31 2.8 1.5 14.0 57.2 2.5 M M
15000 -16.5 2.3 285 59 30 3.2 1.7 12.9 55.2 1.5 M M
14500 -16.0 3.2 285 57 29 3.7 2.0 11.8 53.3 0.5 M M
14000 -15.4 4.3 285 54 28 3.9 2.1 10.8 51.5 -0.4 649 3.3
13500 -14.8 5.4 285 51 26 4.5 2.5 9.9 49.9 -1.2 616 3.1
13000 -14.2 6.4 285 48 25 4.6 2.5 9.1 48.3 -2.1 581 3.0
12500 -13.4 7.9 285 44 23 5.1 2.8 8.3 46.9 -2.8 545 2.8
12000 -12.7 9.1 290 41 21 5.3 2.9 7.5 45.6 -3.5 508 2.6
11500 -11.9 10.6 290 37 19 5.9 3.2 6.9 44.4 -4.2 468 2.4
11000 -11.0 12.2 295 34 17 6.0 3.3 6.3 43.3 -4.8 427 2.2
10500 -10.1 13.8 295 31 16 6.2 3.4 5.7 42.2 -5.4 384 2.0
10250 -9.6 14.7 300 30 16 6.9 3.8 5.4 41.8 -5.7 363 1.8
10000 -9.1 15.6 300 29 15 4.3 2.3 5.2 41.3 -5.9 341 1.7
9750 -8.9 16.0 300 29 15 5.6 3.1 4.7 40.4 -6.4 326 1.7
9500 -8.2 17.2 305 27 14 9.1 5.0 4.6 40.2 -6.6 300 1.5
9250 -7.6 18.3 305 26 13 8.1 4.4 4.4 40.0 -6.7 274 1.4
9000 -7.0 19.4 310 25 13 7.5 4.1 4.3 39.8 -6.8 249 1.3
8750 -6.5 20.3 315 23 12 7.4 4.1 4.1 39.4 -7.1 226 1.1
8500 -5.9 21.4 320 22 11 8.2 4.5 4.0 39.1 -7.2 201 1.0
8250 -5.3 22.5 325 21 11 7.4 4.1 3.8 38.9 -7.4 176 0.9
8000 -4.8 23.4 330 21 11 6.5 3.6 3.6 38.5 -7.7 154 0.8
7750 -4.4 24.1 335 21 11 6.7 3.7 3.4 38.0 -7.9 132 0.7
7500 -3.9 25.0 340 21 11 6.6 3.6 3.1 37.6 -8.2 110 0.6
7250 -3.4 25.9 345 21 11 6.1 3.4 2.9 37.1 -8.5 88 0.4
7000 -3.0 26.6 350 21 11 5.0 2.7 2.5 36.6 -8.8 69 0.3
6750 -2.6 27.3 355 22 11 8.0 4.4 2.2 36.0 -9.1 49 0.2
6500 -1.9 28.6 360 21 11 8.5 4.7 2.2 36.0 -9.2 21 0.1
6250 -1.4 29.5 360 20 10 6.1 3.3 2.0 35.5 -9.5 M M
6000 -0.9 30.4 005 19 10 6.5 3.6 1.7 35.1 -9.8 M M
5750 -0.5 31.1 010 18 9 7.1 3.9 1.5 34.7 -10.1 M M
5500 0.1 32.2 010 14 7 8.5 4.7 1.4 34.4 -10.3 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
03/11/2026 at 0900 MDT | 03/11/2026 at 1200 MDT
|
CAPE... +0.8 LI... +14.0 | CAPE... 0.0 LI... +13.8
CINH... -0.0 K Index... -19.8 | CINH... 0.0 K Index... -16.4
|
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 -59.5 -75.1 280 47 24 -0.9 -0.5 | -60.3 -76.5 280 47 24 -1.3 -0.7
45000 -60.9 -77.6 270 67 35 -0.9 -0.5 | -62.2 -80.0 275 75 38 -1.1 -0.6
40000 -61.1 -78.0 295 91 47 -0.1 -0.1 | -61.5 -78.7 290 96 49 0.5 0.3
38000 -59.1 -74.4 300 99 51 7.5 4.1 | -59.2 -74.6 295 102 52 7.7 4.2
36000 -54.0 -65.2 300 102 53 7.5 4.1 | -54.0 -65.2 295 103 53 7.7 4.2
34000 -49.5 -57.1 300 103 53 7.2 4.0 | -49.4 -56.9 295 103 53 6.9 3.8
32000 -45.2 -49.4 300 100 51 7.2 4.0 | -45.3 -49.5 295 100 52 6.9 3.8
30000 -40.9 -41.6 300 96 50 6.7 3.7 | -41.3 -42.3 300 96 49 5.8 3.2
29000 -38.9 -38.0 300 94 48 6.7 3.7 | -39.5 -39.1 300 91 47 5.9 3.2
28000 -36.9 -34.4 300 92 47 6.7 3.7 | -37.7 -35.9 305 86 44 5.9 3.2
27000 -34.9 -30.8 305 90 46 6.6 3.6 | -36.0 -32.8 305 81 42 6.0 3.3
26000 -33.0 -27.4 300 86 44 6.2 3.4 | -34.1 -29.4 305 76 39 6.2 3.4
25000 -31.1 -24.0 300 82 42 6.2 3.4 | -32.3 -26.1 305 70 36 6.2 3.4
24000 -29.3 -20.7 300 78 40 6.1 3.4 | -30.4 -22.7 305 65 33 6.2 3.4
23000 -27.2 -17.0 300 74 38 7.1 3.9 | -28.1 -18.6 305 62 32 8.0 4.4
22000 -25.1 -13.2 300 69 36 7.1 3.9 | -25.7 -14.3 310 59 30 8.0 4.4
21000 -23.0 -9.4 300 65 33 6.8 3.7 | -23.3 -9.9 310 57 29 7.6 4.2
20000 -20.7 -5.3 300 64 33 5.8 3.2 | -20.7 -5.3 310 58 30 7.0 3.8
19500 -19.9 -3.8 300 64 33 5.8 3.2 | -19.6 -3.3 310 59 30 7.0 3.8
19000 -19.0 -2.2 300 64 33 5.7 3.2 | -18.6 -1.5 310 60 31 7.1 3.9
18500 -18.2 -0.8 305 64 33 4.4 2.4 | -17.6 0.3 310 60 31 5.6 3.1
18000 -17.6 0.3 305 64 33 3.6 2.0 | -16.8 1.8 310 59 30 5.3 2.9
17500 -17.1 1.2 305 63 32 3.5 1.9 | -16.0 3.2 310 58 30 4.8 2.6
17000 -16.7 1.9 305 62 32 1.9 1.1 | -15.5 4.1 310 57 30 3.5 1.9
16500 -16.4 2.5 305 61 31 2.1 1.1 | -14.9 5.2 310 57 29 3.8 2.1
16000 -16.1 3.0 300 60 31 1.5 0.8 | -14.6 5.7 305 56 29 1.1 0.6
15500 -15.9 3.4 300 58 30 1.5 0.8 | -14.4 6.1 305 54 28 1.3 0.7
15000 -15.7 3.7 300 57 29 1.4 0.8 | -14.2 6.4 305 52 27 1.2 0.6
14500 -15.5 4.1 300 54 28 1.4 0.8 | -14.0 6.8 305 49 25 1.1 0.6
14000 -15.3 4.5 300 52 27 1.8 1.0 | -13.8 7.2 305 46 24 1.5 0.8
13500 -15.0 5.0 300 49 25 2.4 1.3 | -13.6 7.5 305 43 22 1.8 1.0
13000 -14.6 5.7 295 45 23 3.0 1.7 | -13.3 8.1 300 40 21 2.4 1.3
12500 -14.0 6.8 295 42 22 4.2 2.3 | -12.9 8.8 300 36 19 3.0 1.7
12000 -13.4 7.9 295 40 20 4.9 2.7 | -12.4 9.7 300 33 17 4.4 2.4
11500 -12.6 9.3 295 37 19 5.9 3.2 | -11.6 11.1 300 29 15 5.4 3.0
11000 -11.7 10.9 295 35 18 5.8 3.2 | -10.8 12.6 300 26 14 6.1 3.4
10500 -10.9 12.4 300 33 17 5.7 3.1 | -9.8 14.4 300 24 12 6.7 3.7
10250 -10.5 13.1 300 32 17 5.5 3.0 | -9.4 15.1 300 23 12 5.6 3.1
10000 -10.1 13.8 300 32 16 3.6 2.0 | -9.0 15.8 300 22 11 3.9 2.1
9750 -9.9 14.2 300 31 16 5.5 3.0 | -8.7 16.3 300 20 11 6.4 3.5
9500 -9.3 15.3 300 29 15 8.4 4.6 | -8.1 17.4 305 19 10 9.0 4.9
9250 -8.7 16.3 305 27 14 6.6 3.6 | -7.5 18.5 305 17 9 6.7 3.7
9000 -8.3 17.1 305 26 13 4.2 2.3 | -7.1 19.2 310 15 8 4.3 2.4
8750 -8.0 17.6 310 24 12 5.8 3.2 | -6.7 19.9 310 13 7 7.1 3.9
8500 -7.5 18.5 315 23 12 8.0 4.4 | -6.1 21.0 310 11 6 9.0 4.9
8250 -6.9 19.6 315 21 11 6.1 3.4 | -5.5 22.1 315 10 5 7.5 4.1
8000 -6.6 20.1 325 20 10 4.6 2.5 | -5.0 23.0 315 8 4 6.1 3.3
7750 -6.2 20.8 330 19 10 6.8 3.7 | -4.5 23.9 320 7 4 10.0 5.5
7500 -5.6 21.9 335 17 9 7.0 3.8 | -3.6 25.5 320 7 4 11.1 6.1
7250 -5.2 22.6 340 16 8 4.9 2.7 | -2.9 26.8 320 7 3 8.2 4.5
7000 -4.9 23.2 345 15 8 3.8 2.1 | -2.3 27.9 325 6 3 7.6 4.2
6750 -4.6 23.7 355 15 7 7.7 4.2 | -1.7 28.9 325 6 3 11.8 6.5
6500 -3.8 25.2 355 13 7 9.7 5.3 | -0.6 30.9 325 6 3 12.8 7.0
6250 -3.2 26.2 360 12 6 7.5 4.1 | 0.1 32.2 330 6 3 9.8 5.4
6000 -2.7 27.1 005 11 6 7.2 3.9 | 0.9 33.6 330 6 3 8.9 4.9
5750 -2.1 28.2 010 10 5 9.6 5.2 | 1.6 34.9 330 5 2 13.7 7.5
5500 -1.1 30.0 015 9 4 17.2 9.5 | 3.2 37.8 335 4 2 28.0 15.4
03/11/2026 at 1500 MDT | 03/11/2026 at 1800 MDT
|
CAPE... 0.0 LI... +10.2 | CAPE... 0.0 LI... +7.1
CINH... -0.0 K Index... -11.4 | CINH... 0.0 K Index... -4.6
|
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 -60.5 -76.9 275 52 27 -0.3 -0.2 | -60.5 -76.9 285 59 30 0.6 0.3
45000 -61.0 -77.8 275 80 41 -0.3 -0.1 | -59.6 -75.3 285 79 40 0.5 0.3
40000 -61.0 -77.8 290 100 51 -0.0 -0.0 | -59.9 -75.8 295 92 47 -0.2 -0.1
38000 -59.4 -74.9 290 105 54 6.3 3.5 | -58.6 -73.5 295 97 50 4.3 2.4
36000 -55.1 -67.2 290 106 55 6.3 3.5 | -56.0 -68.8 300 102 52 4.3 2.4
34000 -51.3 -60.3 290 106 54 6.2 3.4 | -53.1 -63.6 305 105 54 7.0 3.8
32000 -47.6 -53.7 295 99 51 6.2 3.4 | -49.0 -56.2 310 99 51 6.9 3.8
30000 -43.8 -46.8 300 93 48 7.0 3.8 | -44.8 -48.6 310 94 48 7.2 4.0
29000 -41.7 -43.1 300 89 46 7.0 3.8 | -42.6 -44.7 310 89 46 7.3 4.0
28000 -39.6 -39.3 300 84 43 7.0 3.8 | -40.4 -40.7 310 85 44 7.3 4.0
27000 -37.5 -35.5 300 80 41 6.9 3.8 | -38.3 -36.9 310 80 41 7.2 3.9
26000 -35.5 -31.9 300 75 39 6.7 3.7 | -36.2 -33.2 310 77 40 7.1 3.9
25000 -33.5 -28.3 300 70 36 6.7 3.7 | -34.0 -29.2 305 73 38 7.1 3.9
24000 -31.5 -24.7 300 66 34 6.8 3.7 | -31.9 -25.4 305 70 36 7.0 3.9
23000 -29.3 -20.7 300 62 32 7.5 4.1 | -29.9 -21.8 305 66 34 6.9 3.8
22000 -27.0 -16.6 305 59 31 7.5 4.1 | -27.8 -18.0 305 62 32 6.9 3.8
21000 -24.8 -12.6 305 56 29 7.6 4.2 | -25.2 -13.4 305 57 29 7.5 4.1
20000 -21.9 -7.4 305 53 28 7.7 4.2 | -22.9 -9.2 305 54 28 7.5 4.1
19500 -20.8 -5.4 305 52 27 7.7 4.2 | -21.8 -7.2 305 52 27 7.5 4.1
19000 -19.6 -3.3 310 51 26 7.8 4.3 | -20.7 -5.3 305 51 26 7.5 4.1
18500 -18.5 -1.3 310 50 26 6.3 3.5 | -19.6 -3.3 310 49 25 7.2 4.0
18000 -17.6 0.3 305 51 26 6.3 3.5 | -18.5 -1.3 305 47 24 7.3 4.0
17500 -16.6 2.1 305 51 26 5.8 3.2 | -17.4 0.7 305 46 23 6.8 3.7
17000 -15.8 3.6 305 49 25 5.3 2.9 | -16.5 2.3 305 45 23 6.5 3.6
16500 -15.1 4.8 305 47 24 5.2 2.9 | -15.5 4.1 305 45 23 6.4 3.5
16000 -14.4 6.1 305 46 24 3.8 2.1 | -14.6 5.7 305 44 23 5.7 3.1
15500 -13.8 7.2 305 45 23 4.0 2.2 | -13.8 7.2 305 42 22 5.7 3.1
15000 -13.3 8.1 305 43 22 2.3 1.2 | -12.9 8.8 305 40 21 5.3 2.9
14500 -13.0 8.6 300 42 21 2.3 1.2 | -12.2 10.0 305 38 20 5.3 2.9
14000 -12.6 9.3 300 40 20 3.1 1.7 | -11.4 11.5 300 36 18 5.4 3.0
13500 -12.2 10.0 300 37 19 3.2 1.7 | -10.5 13.1 300 33 17 5.4 3.0
13000 -11.6 11.1 295 34 17 4.7 2.6 | -9.7 14.5 295 31 16 6.0 3.3
12500 -10.9 12.4 295 32 16 5.2 2.8 | -8.8 16.2 295 29 15 6.1 3.3
12000 -10.0 14.0 295 29 15 6.1 3.3 | -7.9 17.8 295 28 14 6.5 3.6
11500 -9.1 15.6 295 27 14 6.4 3.5 | -6.9 19.6 290 26 13 6.5 3.6
11000 -8.1 17.4 295 24 12 7.0 3.9 | -5.9 21.4 290 24 13 7.2 3.9
10500 -7.0 19.4 295 21 11 7.5 4.1 | -4.8 23.4 290 22 11 7.6 4.2
10250 -6.5 20.3 295 20 10 5.9 3.2 | -4.3 24.3 290 20 10 5.8 3.2
10000 -6.1 21.0 295 19 10 5.6 3.1 | -3.9 25.0 290 20 10 6.2 3.4
9750 -5.6 21.9 295 17 9 8.4 4.6 | -3.3 26.1 290 18 9 9.0 5.0
9500 -4.9 23.2 295 16 8 9.5 5.2 | -2.6 27.3 290 16 8 9.3 5.1
9250 -4.3 24.3 300 14 7 7.6 4.2 | -2.0 28.4 290 15 8 7.5 4.1
9000 -3.8 25.2 300 12 6 6.1 3.4 | -1.5 29.3 295 14 7 6.4 3.5
8750 -3.3 26.1 300 11 6 8.9 4.9 | -0.9 30.4 295 13 6 8.4 4.6
8500 -2.5 27.5 305 10 5 9.8 5.4 | -0.3 31.5 295 11 6 8.7 4.8
8250 -1.8 28.8 310 9 4 8.7 4.8 | 0.3 32.5 300 10 5 7.6 4.2
8000 -1.2 29.8 310 8 4 7.8 4.3 | 0.9 33.6 300 9 5 7.1 3.9
7750 -0.6 30.9 315 7 4 10.8 5.9 | 1.5 34.7 305 8 4 9.0 4.9
7500 0.3 32.5 315 7 4 10.6 5.8 | 2.2 36.0 305 7 3 9.4 5.2
7250 0.9 33.6 320 7 4 8.1 4.5 | 2.8 37.0 310 7 3 8.4 4.6
7000 1.6 34.9 325 7 3 7.7 4.2 | 3.5 38.3 315 6 3 8.0 4.4
6750 2.2 36.0 325 6 3 11.6 6.3 | 4.1 39.4 320 6 3 10.7 5.9
6500 3.2 37.8 330 6 3 12.7 6.9 | 5.0 41.0 325 5 3 11.4 6.2
6250 4.0 39.2 330 6 3 10.1 5.5 | 5.7 42.3 330 5 2 9.0 4.9
6000 4.8 40.6 335 6 3 9.0 4.9 | 6.4 43.5 335 4 2 9.8 5.4
5750 5.5 41.9 340 5 3 13.7 7.5 | 7.2 45.0 335 5 2 11.3 6.2
5500 7.1 44.8 345 5 3 28.1 15.4 | 8.2 46.8 340 4 2 13.8 7.6
________________________________________________________________________________
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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