Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
197
UXUS97 KBOU 240004
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1703 MST Saturday, November 23, 2024
This forecast is for Sunday, November 24, 2024:
If the trigger temperature of 61.1 F/16.2 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 33 ft/min (0.2 m/s)
Maximum height of thermals.................. 7527 ft MSL (2221 ft AGL)
Forecast maximum temperature................... 57.0 F/14.3 C
Time of trigger temperature.................... None
Time of overdevelopment........................ 1600 MST
Middle/high clouds during soaring window....... Overcast thin high
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 5947 ft MSL (641 ft AGL)
Thermal soaring outlook for Monday 11/25....... Poor
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)................ Weak PVA
Potential height of wave....................... 44932 ft MSL (39626 ft AGL)
Wave soaring outlook for Monday 11/25.......... Poor
Remarks...
Sunrise/Sunset.................... 06:55:03 / 16:37:42 MST
Total possible sunshine........... 9 hr 42 min 39 sec (582 min 39 sec)
Altitude of sun at 11:46:23 MST... 29.39 degrees
Upper air data from numerical model forecast valid on 11/24/2024 at 0500 MST
Freezing level.................. 11962 ft MSL (6656 ft AGL)
Convective condensation level... 19004 ft MSL (13698 ft AGL)
Lifted condensation level....... 14292 ft MSL (8987 ft AGL)
Lifted index.................... +9.7
K index......................... +13.0
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 -64.9 -84.8 260 59 30 -0.4 -0.2 M M M M M
45000 -65.4 -85.7 245 89 46 2.6 1.4 M M M M M
40000 -59.9 -75.8 245 82 42 3.6 2.0 M M M M M
38000 -57.1 -70.8 250 80 41 5.5 3.0 M M M M M
36000 -53.8 -64.8 250 78 40 5.5 3.0 M M M M M
34000 -50.1 -58.2 250 77 40 8.2 4.5 M M M M M
32000 -44.6 -48.3 250 76 39 8.2 4.5 M M M M M
30000 -39.6 -39.3 250 75 39 8.4 4.6 36.2 97.2 16.8 M M
29000 -37.1 -34.8 250 74 38 8.4 4.6 35.6 96.0 16.6 M M
28000 -34.6 -30.3 250 73 37 8.4 4.6 35.1 95.1 16.4 M M
27000 -32.1 -25.8 250 72 37 7.6 4.2 34.6 94.3 16.2 M M
26000 -29.9 -21.8 250 70 36 7.4 4.0 33.6 92.5 15.6 M M
25000 -27.7 -17.9 250 69 35 7.4 4.0 32.7 90.9 15.1 M M
24000 -25.5 -13.9 250 67 35 7.1 3.9 32.0 89.5 14.7 M M
23000 -23.5 -10.3 255 65 33 6.6 3.6 30.7 87.3 13.8 M M
22000 -21.5 -6.7 255 62 32 6.7 3.7 29.6 85.3 13.0 M M
21000 -19.6 -3.3 255 60 31 7.1 3.9 28.6 83.5 12.3 M M
20000 -17.4 0.7 255 57 29 7.4 4.1 27.7 81.8 11.6 M M
19500 -16.3 2.7 255 56 29 7.4 4.1 27.3 81.1 11.3 M M
19000 -15.2 4.6 255 55 28 7.5 4.1 26.9 80.4 11.0 M M
18500 -14.1 6.6 260 53 27 7.4 4.1 26.5 79.8 10.7 M M
18000 -13.1 8.4 260 52 27 7.2 4.0 26.1 79.0 10.4 M M
17500 -12.0 10.4 260 50 26 7.2 4.0 25.7 78.2 10.0 M M
17000 -10.9 12.4 260 48 25 7.3 4.0 25.3 77.5 9.7 M M
16500 -9.3 15.3 255 43 22 7.3 4.0 24.6 76.3 9.2 M M
16000 -8.3 17.1 255 40 20 7.0 3.9 24.2 75.5 8.8 M M
15500 -7.2 19.0 255 36 19 7.1 3.9 23.7 74.7 8.4 M M
15000 -6.2 20.8 255 33 17 6.5 3.6 23.3 73.9 8.1 M M
14500 -5.3 22.5 255 29 15 6.3 3.5 22.7 72.8 7.6 M M
14000 -4.3 24.3 255 25 13 6.4 3.5 22.1 71.9 7.1 M M
13500 -3.4 25.9 250 21 11 6.6 3.6 21.6 70.9 6.6 M M
13000 -2.4 27.7 250 18 9 7.0 3.8 21.1 70.0 6.2 M M
12500 -1.2 29.8 250 20 10 8.4 4.6 20.8 69.4 5.9 M M
12000 0.0 32.0 255 23 12 8.0 4.4 20.6 69.1 5.8 M M
11500 0.9 33.6 255 23 12 4.2 2.3 19.9 67.9 5.2 M M
11000 1.5 34.7 250 20 11 4.6 2.5 19.1 66.4 4.4 M M
10500 2.3 36.1 250 21 11 5.8 3.2 18.4 65.1 3.7 M M
10250 2.7 36.9 255 21 11 4.9 2.7 18.1 64.5 3.4 M M
10000 3.0 37.4 255 20 10 3.3 1.8 17.6 63.7 3.0 M M
9750 3.3 37.9 255 18 9 5.1 2.8 17.1 62.8 2.6 M M
9500 3.8 38.8 260 17 9 6.4 3.5 16.8 62.3 2.3 M M
9250 4.3 39.7 265 17 9 7.0 3.8 16.6 61.8 2.1 M M
9000 4.8 40.6 265 17 9 3.4 1.9 16.3 61.4 1.9 M M
8750 4.9 40.8 270 14 7 3.4 1.9 15.7 60.2 1.3 M M
8500 5.4 41.7 270 12 6 7.1 3.9 15.4 59.8 1.0 M M
8250 5.9 42.6 275 10 5 6.2 3.4 15.2 59.3 0.8 M M
8000 6.4 43.5 280 9 4 6.2 3.4 14.9 58.8 0.6 M M
7750 6.8 44.2 280 6 3 5.9 3.3 14.6 58.3 0.3 M M
7500 7.3 45.1 280 4 2 5.9 3.3 14.3 57.8 -0.0 133 0.7
7250 7.7 45.9 280 2 1 6.1 3.4 14.0 57.2 -0.3 112 0.6
7000 8.3 46.9 000 0 0 8.7 4.8 13.8 56.9 -0.5 88 0.4
6750 9.0 48.2 095 1 1 7.9 4.3 13.8 56.8 -0.5 60 0.3
6500 9.5 49.1 100 2 1 9.4 5.2 13.6 56.5 -0.7 35 0.2
6250 10.1 50.2 100 4 2 -1.0 -0.6 13.4 56.2 -0.8 11 0.1
6000 9.4 48.9 125 3 2 -11.3 -6.2 12.0 53.6 -2.3 26 0.1
5750 8.3 46.9 160 3 2 -21.4 -11.7 10.2 50.4 -4.1 49 0.2
5500 5.5 41.9 185 5 3 -54.1 -29.7 6.7 44.1 -7.7 128 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/24/2024 at 0800 MST | 11/24/2024 at 1100 MST
|
CAPE... 0.0 LI... +4.1 | CAPE... 0.0 LI... +5.5
CINH... -0.2 K Index... +9.3 | CINH... -0.2 K Index... +5.4
|
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 -64.2 -83.6 255 59 31 0.5 0.3 | -63.8 -82.8 250 64 33 0.8 0.4
45000 -63.4 -82.1 245 82 42 1.5 0.8 | -62.6 -80.7 250 73 38 1.0 0.5
40000 -60.1 -76.2 255 87 45 2.2 1.2 | -60.7 -77.3 260 97 50 1.3 0.7
38000 -58.0 -72.4 260 89 46 4.7 2.6 | -58.6 -73.5 260 102 52 5.8 3.2
36000 -55.2 -67.4 255 89 46 4.7 2.6 | -55.1 -67.2 260 101 52 5.9 3.2
34000 -52.0 -61.6 255 89 46 8.7 4.8 | -51.3 -60.3 255 100 52 8.2 4.5
32000 -46.9 -52.4 255 87 45 8.5 4.7 | -46.6 -51.9 260 98 51 8.0 4.4
30000 -41.1 -42.0 260 84 43 8.7 4.8 | -41.2 -42.2 260 95 49 7.8 4.3
29000 -38.5 -37.3 255 82 42 8.7 4.8 | -38.9 -38.0 260 92 47 7.8 4.3
28000 -35.9 -32.6 255 80 41 8.7 4.8 | -36.5 -33.7 260 89 46 7.8 4.3
27000 -33.3 -27.9 255 78 40 8.4 4.6 | -34.2 -29.6 260 86 44 7.9 4.4
26000 -30.9 -23.6 255 76 39 8.2 4.5 | -31.8 -25.2 255 81 42 8.0 4.4
25000 -28.4 -19.1 255 75 39 8.2 4.5 | -29.4 -20.9 255 77 40 8.1 4.4
24000 -26.0 -14.8 255 73 38 8.1 4.4 | -26.9 -16.4 255 73 38 8.0 4.4
23000 -23.7 -10.7 255 71 37 7.6 4.2 | -24.6 -12.3 255 72 37 7.9 4.3
22000 -21.4 -6.5 250 69 36 7.6 4.2 | -22.2 -8.0 250 70 36 7.9 4.3
21000 -19.2 -2.6 250 67 35 6.7 3.7 | -19.8 -3.6 250 69 36 7.5 4.1
20000 -17.4 0.7 250 61 31 5.9 3.2 | -17.8 -0.0 250 67 34 6.9 3.8
19500 -16.5 2.3 250 58 30 5.9 3.2 | -16.7 1.9 250 65 34 6.9 3.8
19000 -15.7 3.7 250 55 28 5.9 3.2 | -15.7 3.7 245 64 33 6.9 3.8
18500 -14.8 5.4 245 52 27 5.9 3.2 | -14.7 5.5 245 63 32 6.7 3.7
18000 -13.9 7.0 250 52 27 6.0 3.3 | -13.8 7.2 245 62 32 5.0 2.7
17500 -12.6 9.3 250 52 27 5.9 3.2 | -13.1 8.4 245 61 31 5.1 2.8
17000 -11.8 10.8 250 50 26 5.2 2.8 | -12.3 9.9 245 59 30 5.0 2.7
16500 -11.1 12.0 250 47 24 5.1 2.8 | -11.2 11.8 245 55 28 4.9 2.7
16000 -10.2 13.6 250 45 23 6.7 3.7 | -10.5 13.1 250 54 28 5.4 3.0
15500 -9.3 15.3 250 44 23 6.8 3.7 | -9.7 14.5 250 55 29 5.5 3.0
15000 -8.3 17.1 250 44 23 6.8 3.7 | -8.9 16.0 250 57 29 5.0 2.8
14500 -7.3 18.9 250 45 23 6.8 3.7 | -8.2 17.2 250 55 28 4.7 2.6
14000 -6.3 20.7 255 46 23 6.7 3.7 | -7.6 18.3 250 54 28 5.1 2.8
13500 -5.3 22.5 255 44 23 6.7 3.7 | -6.7 19.9 250 51 26 6.4 3.5
13000 -4.3 24.3 255 43 22 6.8 3.7 | -5.8 21.6 255 49 25 6.5 3.6
12500 -3.3 26.1 255 41 21 7.3 4.0 | -4.8 23.4 255 46 24 7.2 4.0
12000 -2.2 28.0 255 39 20 7.3 4.0 | -3.8 25.2 255 42 22 7.2 3.9
11500 -1.1 30.0 255 36 19 7.2 3.9 | -2.7 27.1 255 38 19 7.6 4.2
11000 -0.1 31.8 255 32 17 7.1 3.9 | -1.5 29.3 255 34 17 7.5 4.1
10500 0.8 33.4 255 29 15 5.3 2.9 | -0.6 30.9 255 30 15 5.9 3.2
10250 1.2 34.2 255 28 15 5.5 3.0 | -0.1 31.8 255 28 15 6.7 3.7
10000 1.7 35.1 255 26 14 5.7 3.1 | 0.5 32.9 250 26 13 8.3 4.6
9750 2.1 35.8 255 24 12 5.9 3.3 | 1.1 34.0 250 24 12 8.6 4.7
9500 2.5 36.5 255 23 12 5.8 3.2 | 1.7 35.1 250 22 11 7.9 4.3
9250 3.0 37.4 255 22 11 6.3 3.4 | 2.3 36.1 250 21 11 8.5 4.7
9000 3.4 38.1 255 21 11 4.7 2.6 | 2.9 37.2 250 19 10 6.8 3.7
8750 3.7 38.7 255 19 10 5.5 3.0 | 3.4 38.1 250 18 9 6.9 3.8
8500 4.3 39.7 255 17 9 7.8 4.3 | 4.0 39.2 250 17 9 8.9 4.9
8250 4.8 40.6 250 16 8 6.9 3.8 | 4.7 40.5 245 16 8 7.9 4.3
8000 5.4 41.7 250 14 7 8.1 4.5 | 5.3 41.5 245 15 8 10.0 5.5
7750 6.0 42.8 245 13 7 8.6 4.7 | 6.1 43.0 235 14 7 10.1 5.5
7500 6.6 43.9 240 11 6 8.0 4.4 | 6.8 44.2 230 13 7 8.3 4.6
7250 7.3 45.1 230 9 5 8.0 4.4 | 7.4 45.3 225 12 6 8.5 4.7
7000 7.8 46.0 225 8 4 6.9 3.8 | 8.0 46.4 220 11 6 6.0 3.3
6750 8.3 46.9 220 7 4 6.6 3.6 | 8.4 47.1 215 10 5 6.0 3.3
6500 8.9 48.0 210 6 3 8.7 4.8 | 8.9 48.0 215 9 4 7.3 4.0
6250 9.4 48.9 190 5 2 3.2 1.8 | 9.4 48.9 215 7 4 7.3 4.0
6000 9.3 48.7 185 5 3 -2.8 -1.5 | 10.0 50.0 220 7 4 8.1 4.4
5750 9.1 48.4 185 6 3 -4.6 -2.5 | 10.6 51.1 225 7 3 7.8 4.3
5500 8.1 46.6 190 6 3 -26.9 -14.8 | 11.2 52.2 230 6 3 11.4 6.2
11/24/2024 at 1400 MST | 11/24/2024 at 1700 MST
|
CAPE... 0.0 LI... +4.3 | CAPE... 0.0 LI... +5.8
CINH... 0.0 K Index... +12.2 | CINH... 0.0 K Index... -5.0
|
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 -62.7 -80.9 255 64 33 1.2 0.6 | -61.9 -79.4 255 59 30 0.5 0.3
45000 -60.8 -77.4 250 76 39 1.2 0.7 | -61.1 -78.0 260 76 39 0.5 0.3
40000 -58.9 -74.0 260 88 45 1.3 0.7 | -59.3 -74.7 260 84 43 1.2 0.7
38000 -57.1 -70.8 260 96 49 4.6 2.5 | -57.6 -71.7 260 89 46 4.7 2.6
36000 -54.4 -65.9 255 106 55 4.6 2.5 | -54.8 -66.6 260 98 51 4.7 2.6
34000 -51.4 -60.5 255 115 59 8.5 4.7 | -51.8 -61.2 255 106 55 8.5 4.7
32000 -46.5 -51.7 255 111 57 8.1 4.5 | -46.7 -52.1 255 106 55 8.5 4.7
30000 -41.1 -42.0 255 105 54 7.3 4.0 | -41.6 -42.9 255 105 54 7.7 4.2
29000 -38.9 -38.0 255 99 51 7.4 4.0 | -38.9 -38.0 255 100 52 7.5 4.1
28000 -36.7 -34.1 255 94 48 7.4 4.0 | -36.6 -33.9 255 96 50 7.5 4.1
27000 -34.5 -30.1 255 89 46 7.4 4.0 | -34.4 -29.9 255 93 48 7.5 4.1
26000 -32.3 -26.1 255 87 45 7.4 4.0 | -32.1 -25.8 255 90 46 7.5 4.1
25000 -30.1 -22.2 250 85 44 7.4 4.1 | -29.9 -21.8 255 88 45 7.5 4.1
24000 -27.9 -18.2 250 84 43 7.3 4.0 | -27.6 -17.7 255 85 44 7.6 4.2
23000 -25.4 -13.7 250 79 40 8.4 4.6 | -25.5 -13.9 250 83 43 6.9 3.8
22000 -22.9 -9.2 245 73 37 8.4 4.6 | -23.4 -10.1 250 80 41 6.9 3.8
21000 -20.4 -4.7 245 67 34 7.7 4.2 | -21.4 -6.5 250 78 40 6.6 3.6
20000 -18.6 -1.5 245 69 36 5.7 3.2 | -19.7 -3.5 250 74 38 5.2 2.9
19500 -17.7 0.1 245 71 37 5.8 3.2 | -18.9 -2.0 250 71 37 5.2 2.9
19000 -16.9 1.6 245 73 38 5.8 3.2 | -18.2 -0.8 250 69 36 5.2 2.9
18500 -16.0 3.2 245 75 38 5.8 3.2 | -17.4 0.7 250 67 34 5.5 3.0
18000 -15.2 4.6 245 74 38 5.1 2.8 | -16.7 1.9 250 64 33 3.2 1.8
17500 -14.5 5.9 245 71 36 5.1 2.8 | -16.2 2.8 255 59 31 3.5 1.9
17000 -13.7 7.3 245 68 35 4.1 2.3 | -15.7 3.7 255 55 28 3.4 1.9
16500 -13.2 8.2 250 67 34 3.6 2.0 | -15.2 4.6 260 49 25 3.4 1.9
16000 -12.7 9.1 250 66 34 3.5 1.9 | -14.7 5.5 260 44 23 3.7 2.0
15500 -12.3 9.9 250 63 32 2.5 1.4 | -14.0 6.8 265 41 21 5.4 3.0
15000 -11.8 10.8 255 57 29 4.6 2.5 | -13.2 8.2 270 40 20 5.4 3.0
14500 -10.9 12.4 255 52 27 6.7 3.7 | -12.1 10.2 270 41 21 5.0 2.7
14000 -9.9 14.2 255 47 24 7.3 4.0 | -11.4 11.5 275 43 22 5.4 2.9
13500 -8.6 16.5 255 42 22 9.0 5.0 | -10.5 13.1 275 43 22 6.5 3.6
13000 -7.3 18.9 255 38 19 9.0 4.9 | -9.6 14.7 275 41 21 6.6 3.6
12500 -6.0 21.2 255 34 17 9.3 5.1 | -8.5 16.7 275 40 20 7.6 4.2
12000 -4.6 23.7 260 30 15 9.2 5.1 | -7.4 18.7 270 38 20 7.7 4.2
11500 -3.3 26.1 260 26 13 8.4 4.6 | -6.1 21.0 270 35 18 9.3 5.1
11000 -2.1 28.2 260 21 11 8.4 4.6 | -4.8 23.4 270 32 16 9.1 5.0
10500 -1.0 30.2 265 17 9 6.0 3.3 | -3.5 25.7 270 30 16 8.4 4.6
10250 -0.6 30.9 265 16 8 6.8 3.7 | -2.9 26.8 270 30 15 9.2 5.0
10000 -0.0 32.0 270 14 7 8.6 4.7 | -2.1 28.2 270 29 15 12.3 6.8
9750 0.6 33.1 270 13 7 7.5 4.1 | -1.2 29.8 270 28 14 11.1 6.1
9500 1.1 34.0 275 12 6 6.1 3.3 | -0.5 31.1 270 26 13 8.6 4.7
9250 1.6 34.9 275 11 5 6.4 3.5 | 0.2 32.4 270 24 13 9.4 5.2
9000 2.1 35.8 280 9 5 6.8 3.7 | 0.9 33.6 270 23 12 8.7 4.8
8750 2.6 36.7 285 9 5 7.1 3.9 | 1.5 34.7 270 21 11 8.6 4.7
8500 3.1 37.6 285 8 4 7.0 3.8 | 2.1 35.8 275 19 10 9.0 5.0
8250 3.7 38.7 290 7 4 6.3 3.5 | 2.8 37.0 275 18 9 9.0 4.9
8000 4.2 39.6 295 6 3 9.2 5.0 | 3.5 38.3 280 17 8 8.2 4.5
7750 5.0 41.0 305 5 3 10.0 5.5 | 4.0 39.2 285 15 8 7.7 4.2
7500 5.6 42.1 320 4 2 7.7 4.2 | 4.6 40.3 290 14 7 8.0 4.4
7250 6.2 43.2 335 4 2 8.3 4.6 | 5.2 41.4 295 13 7 8.1 4.4
7000 6.8 44.2 345 4 2 8.2 4.5 | 5.8 42.4 300 13 6 8.3 4.6
6750 7.5 45.5 350 4 2 9.3 5.1 | 6.4 43.5 305 12 6 8.6 4.7
6500 8.2 46.8 350 4 2 10.0 5.5 | 7.1 44.8 310 12 6 8.8 4.8
6250 8.9 48.0 355 4 2 9.8 5.4 | 7.7 45.9 320 11 6 8.6 4.7
6000 9.6 49.3 355 4 2 9.8 5.4 | 8.3 46.9 325 11 6 8.5 4.7
5750 10.4 50.7 355 4 2 10.2 5.6 | 8.9 48.0 330 10 5 8.3 4.5
5500 11.2 52.2 355 4 2 13.1 7.2 | 9.4 48.9 335 9 5 2.2 1.2
________________________________________________________________________________
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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