Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
067
UXUS97 KBOU 031204
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0503 MST Monday, November 3, 2025
This forecast is for Monday, November 3, 2025:
If the trigger temperature of 68.0 F/20.0 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 182 ft/min (0.9 m/s)
Maximum height of thermals.................. 8400 ft MSL (3077 ft AGL)
Forecast maximum temperature................... 61.0 F/16.6 C
Time of trigger temperature.................... None
Time of overdevelopment........................ 1100 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................. 7750 ft MSL (2427 ft AGL)
Thermal soaring outlook for Tuesday 11/04...... Good
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....................... 40202 ft MSL (34879 ft AGL)
Wave soaring outlook for Tuesday 11/04......... Poor
Remarks...
Sunrise/Sunset.................... 06:31:05 / 16:54:54 MST
Total possible sunshine........... 10 hr 23 min 48 sec (623 min 48 sec)
Altitude of sun at 11:42:59 MST... 34.77 degrees
Upper air data from numerical model forecast valid on 11/03/2025 at 0500 MST
Freezing level.................. 14986 ft MSL (9663 ft AGL)
Convective condensation level... 20574 ft MSL (15251 ft AGL)
Lifted condensation level....... 13992 ft MSL (8668 ft AGL)
Lifted index.................... +10.4
K index......................... -14.0
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 -66.5 -87.7 265 39 20 2.9 1.6 M M M M M
45000 -62.3 -80.1 260 48 25 2.3 1.3 M M M M M
40000 -58.5 -73.3 250 69 36 5.5 3.0 M M M M M
38000 -54.7 -66.5 255 62 32 6.4 3.5 M M M M M
36000 -50.9 -59.6 255 56 29 6.4 3.5 M M M M M
34000 -46.2 -51.2 255 53 27 8.5 4.6 M M M M M
32000 -41.1 -42.0 255 51 26 8.5 4.7 M M M M M
30000 -35.5 -31.9 255 47 24 8.4 4.6 40.1 104.2 18.2 M M
29000 -33.0 -27.4 255 45 23 8.4 4.6 39.6 103.2 18.0 M M
28000 -30.5 -22.9 255 43 22 8.1 4.4 39.2 102.5 17.9 M M
27000 -28.2 -18.8 255 41 21 7.5 4.1 38.2 100.8 17.4 M M
26000 -26.0 -14.8 255 39 20 7.5 4.1 37.4 99.3 16.9 M M
25000 -23.7 -10.7 250 37 19 7.5 4.1 36.6 97.9 16.5 M M
24000 -21.4 -6.5 255 35 18 8.2 4.5 35.9 96.7 16.1 M M
23000 -18.9 -2.0 255 34 17 8.2 4.5 35.3 95.6 15.8 M M
22000 -16.5 2.3 260 32 17 8.2 4.5 34.8 94.7 15.5 M M
21000 -14.0 6.8 260 30 16 8.4 4.6 34.3 93.7 15.2 M M
20000 -11.5 11.3 265 28 14 8.4 4.6 33.8 92.8 15.0 M M
19500 -10.2 13.6 270 27 14 8.4 4.6 33.6 92.5 14.9 M M
19000 -9.0 15.8 270 26 13 8.0 4.4 33.4 92.1 14.8 M M
18500 -7.8 18.0 270 24 13 8.0 4.4 33.1 91.5 14.6 M M
18000 -6.6 20.1 265 23 12 7.9 4.3 32.8 91.0 14.4 M M
17500 -5.5 22.1 265 22 11 7.1 3.9 32.3 90.2 14.2 M M
17000 -4.4 24.1 265 21 11 7.2 4.0 31.9 89.4 13.9 M M
16500 -3.3 26.1 265 20 10 6.8 3.7 31.5 88.6 13.5 M M
16000 -1.9 28.6 260 19 10 6.6 3.6 30.7 87.2 12.9 M M
15500 -0.9 30.4 260 19 10 6.9 3.8 30.2 86.3 12.5 M M
15000 0.2 32.4 260 18 9 6.9 3.8 29.7 85.5 12.2 M M
14500 1.2 34.2 260 18 9 6.7 3.7 29.2 84.6 11.8 M M
14000 2.2 36.0 260 17 9 6.6 3.6 28.7 83.7 11.4 M M
13500 3.1 37.6 255 17 9 6.4 3.5 28.2 82.8 11.0 M M
13000 4.1 39.4 255 17 9 6.2 3.4 27.6 81.7 10.4 M M
12500 5.0 41.0 255 17 9 6.0 3.3 27.1 80.7 10.0 M M
12000 5.8 42.4 255 17 9 5.4 3.0 26.4 79.5 9.4 M M
11500 6.6 43.9 255 16 8 5.1 2.8 25.7 78.3 8.8 M M
11000 7.2 45.0 250 16 8 3.6 1.9 24.8 76.6 7.9 M M
10500 7.7 45.9 250 16 8 3.0 1.6 23.8 74.9 7.0 M M
10250 7.8 46.0 250 15 8 0.4 0.2 23.2 73.8 6.4 M M
10000 7.8 46.0 250 15 8 -0.0 -0.0 22.4 72.4 5.7 M M
9750 7.8 46.0 245 14 7 1.0 0.5 21.7 71.1 5.0 M M
9500 7.8 46.0 245 14 7 -0.2 -0.1 21.0 69.8 4.3 M M
9250 7.7 45.9 240 13 7 -1.9 -1.0 20.1 68.3 3.5 M M
9000 7.5 45.5 240 12 6 -2.6 -1.4 19.2 66.6 2.6 M M
8750 7.3 45.1 235 11 6 -3.8 -2.1 18.2 64.8 1.6 M M
8500 6.9 44.4 230 10 5 -4.5 -2.4 17.1 62.8 0.5 M M
8250 6.6 43.9 225 9 5 -4.6 -2.5 16.0 60.8 -0.6 284 1.4
8000 6.2 43.2 220 9 4 -3.9 -2.1 14.9 58.9 -1.7 287 1.5
7750 5.8 42.4 215 8 4 -8.7 -4.8 13.8 56.8 -2.8 292 1.5
7500 5.0 41.0 200 8 4 -8.3 -4.6 12.2 54.0 -4.4 309 1.6
7250 4.6 40.3 190 8 4 -3.7 -2.1 11.1 52.0 -5.5 313 1.6
7000 4.2 39.6 180 8 4 -4.8 -2.6 10.0 50.0 -6.6 317 1.6
6750 3.9 39.0 170 9 4 -5.1 -2.8 8.9 48.1 -7.7 320 1.6
6500 3.5 38.3 160 9 4 -3.4 -1.9 7.8 46.0 -8.9 325 1.6
6250 3.3 37.9 155 8 4 -1.4 -0.8 6.9 44.5 -9.7 321 1.6
6000 3.2 37.8 145 7 3 -2.0 -1.1 6.0 42.9 -10.6 318 1.6
5750 3.0 37.4 145 6 3 -5.2 -2.9 5.1 41.2 -11.6 318 1.6
5500 2.4 36.3 145 5 2 -11.2 -6.1 3.7 38.7 -13.0 329 1.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/03/2025 at 0800 MST | 11/03/2025 at 1100 MST
|
CAPE... 0.0 LI... +7.2 | CAPE... 0.0 LI... +5.6
CINH... -0.2 K Index... -11.2 | CINH... 0.0 K Index... -6.0
|
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 -65.0 -85.0 270 37 19 3.0 1.7 | -64.8 -84.6 270 35 18 3.6 2.0
45000 -60.8 -77.4 255 45 23 1.1 0.6 | -60.2 -76.4 255 45 23 0.5 0.3
40000 -59.1 -74.4 245 71 37 4.4 2.4 | -59.3 -74.7 245 71 36 3.4 1.9
38000 -55.2 -67.4 245 66 34 6.6 3.6 | -55.3 -67.5 245 71 36 6.6 3.6
36000 -51.2 -60.2 250 60 31 6.6 3.6 | -51.4 -60.5 245 70 36 6.6 3.6
34000 -46.5 -51.7 250 56 29 8.4 4.6 | -46.7 -52.1 245 65 34 8.4 4.6
32000 -41.5 -42.7 250 53 27 8.4 4.6 | -41.7 -43.1 245 57 29 8.4 4.6
30000 -36.0 -32.8 250 49 25 7.9 4.3 | -36.2 -33.2 250 51 26 7.9 4.4
29000 -33.6 -28.5 250 47 24 7.9 4.3 | -33.8 -28.8 250 49 25 7.9 4.4
28000 -31.3 -24.3 250 45 23 7.8 4.3 | -31.5 -24.7 250 47 24 7.8 4.3
27000 -29.0 -20.2 245 43 22 7.5 4.1 | -29.4 -20.9 245 45 23 6.9 3.8
26000 -26.8 -16.2 245 41 21 7.6 4.1 | -27.3 -17.1 245 44 23 6.9 3.8
25000 -24.5 -12.1 245 40 20 7.5 4.1 | -25.2 -13.4 245 42 22 6.8 3.7
24000 -22.1 -7.8 245 37 19 8.3 4.6 | -22.9 -9.2 245 40 21 8.4 4.6
23000 -19.7 -3.5 250 34 17 8.3 4.6 | -20.4 -4.7 245 38 20 8.5 4.7
22000 -17.2 1.0 250 31 16 8.3 4.6 | -17.9 -0.2 245 36 19 8.5 4.7
21000 -14.6 5.7 250 29 15 8.8 4.8 | -15.3 4.5 245 34 17 8.6 4.7
20000 -11.9 10.6 250 27 14 8.8 4.8 | -12.7 9.1 245 32 16 8.6 4.7
19500 -10.6 12.9 250 26 13 8.9 4.9 | -11.5 11.3 245 30 16 8.6 4.7
19000 -9.3 15.3 250 25 13 8.3 4.5 | -10.2 13.6 245 29 15 8.5 4.7
18500 -8.1 17.4 250 24 12 8.1 4.4 | -8.9 16.0 250 29 15 8.5 4.7
18000 -6.9 19.6 250 23 12 8.1 4.4 | -7.6 18.3 250 28 14 8.5 4.7
17500 -5.7 21.7 250 22 12 7.8 4.3 | -6.4 20.5 250 27 14 7.8 4.3
17000 -4.5 23.9 250 21 11 7.8 4.3 | -5.2 22.6 250 26 14 7.9 4.3
16500 -2.9 26.8 250 20 10 6.9 3.8 | -4.0 24.8 250 26 13 7.7 4.2
16000 -1.8 28.8 250 19 10 7.0 3.9 | -2.3 27.9 255 25 13 7.7 4.2
15500 -0.8 30.6 250 19 10 6.4 3.5 | -1.2 29.8 255 24 12 7.2 4.0
15000 0.1 32.2 250 18 9 6.4 3.5 | -0.1 31.8 255 23 12 7.2 3.9
14500 1.1 34.0 250 17 9 6.1 3.3 | 1.0 33.8 255 22 12 6.9 3.8
14000 1.9 35.4 250 16 8 5.9 3.3 | 2.0 35.6 250 21 11 6.8 3.7
13500 2.8 37.0 245 15 8 5.8 3.2 | 3.0 37.4 250 20 10 6.7 3.7
13000 3.6 38.5 245 15 8 5.5 3.0 | 3.9 39.0 250 19 10 6.4 3.5
12500 4.4 39.9 240 14 7 5.4 3.0 | 4.9 40.8 250 18 9 6.4 3.5
12000 5.2 41.4 235 14 7 5.1 2.8 | 5.8 42.4 245 17 9 6.1 3.3
11500 5.9 42.6 230 13 7 4.9 2.7 | 6.7 44.1 240 17 9 6.0 3.3
11000 6.6 43.9 225 13 7 4.1 2.2 | 7.5 45.5 240 16 8 4.8 2.6
10500 7.2 45.0 220 14 7 3.6 2.0 | 8.2 46.8 235 15 8 4.3 2.4
10250 7.4 45.3 215 13 7 1.5 0.8 | 8.4 47.1 230 15 8 1.6 0.9
10000 7.5 45.5 210 13 7 2.3 1.2 | 8.5 47.3 230 15 8 2.5 1.4
9750 7.7 45.9 210 14 7 4.0 2.2 | 8.8 47.8 225 15 7 4.9 2.7
9500 8.0 46.4 210 14 7 2.3 1.3 | 9.1 48.4 220 14 7 3.4 1.8
9250 8.0 46.4 205 15 8 0.2 0.1 | 9.3 48.7 220 14 7 1.5 0.8
9000 8.0 46.4 205 15 8 -0.2 -0.1 | 9.3 48.7 215 13 7 -0.3 -0.2
8750 8.0 46.4 200 15 8 0.3 0.2 | 9.2 48.6 215 13 6 -1.4 -0.8
8500 8.0 46.4 200 14 7 -1.2 -0.7 | 9.1 48.4 210 12 6 -2.6 -1.4
8250 7.7 45.9 195 14 7 -2.8 -1.5 | 8.8 47.8 205 11 6 -3.7 -2.1
8000 7.5 45.5 190 14 7 -2.4 -1.3 | 8.5 47.3 200 10 5 -3.9 -2.2
7750 7.3 45.1 185 14 7 -2.1 -1.1 | 8.1 46.6 195 9 5 -7.8 -4.3
7500 7.1 44.8 180 12 6 -2.6 -1.4 | 7.4 45.3 190 7 4 -7.0 -3.8
7250 6.9 44.4 175 12 6 -3.8 -2.1 | 7.1 44.8 185 6 3 -3.1 -1.7
7000 6.6 43.9 170 12 6 -2.1 -1.1 | 6.7 44.1 170 5 2 -5.5 -3.0
6750 6.4 43.5 165 12 6 -7.7 -4.2 | 6.4 43.5 150 4 2 1.4 0.8
6500 5.5 41.9 155 12 6 -9.3 -5.1 | 6.9 44.4 140 4 2 8.3 4.5
6250 5.1 41.2 150 11 6 -5.5 -3.0 | 7.5 45.5 135 3 2 9.0 5.0
6000 4.6 40.3 145 10 5 -4.9 -2.7 | 8.0 46.4 130 3 1 3.2 1.8
5750 4.4 39.9 140 8 4 -2.4 -1.3 | 8.1 46.6 015 2 1 6.4 3.5
5500 4.1 39.4 130 5 3 -4.4 -2.4 | 9.5 49.1 010 2 1 29.7 16.3
11/03/2025 at 1400 MST | 11/03/2025 at 1700 MST
|
CAPE... 0.0 LI... +4.0 | CAPE... 0.0 LI... +2.2
CINH... 0.0 K Index... +7.7 | CINH... 0.0 K Index... +14.0
|
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 -64.6 -84.3 260 39 20 3.0 1.6 | -64.9 -84.8 265 39 20 2.5 1.4
45000 -60.7 -77.3 260 51 26 0.7 0.4 | -61.1 -78.0 265 48 25 2.8 1.6
40000 -59.5 -75.1 250 74 38 3.8 2.1 | -56.9 -70.4 250 63 32 2.9 1.6
38000 -55.2 -67.4 250 75 38 7.1 3.9 | -53.4 -64.1 250 69 36 5.4 2.9
36000 -50.9 -59.6 245 75 39 7.1 3.9 | -50.2 -58.4 245 76 39 5.3 2.9
34000 -46.2 -51.2 245 72 37 8.3 4.6 | -45.9 -50.6 245 76 39 8.1 4.4
32000 -41.2 -42.2 245 68 35 8.3 4.6 | -41.0 -41.8 245 73 38 8.1 4.4
30000 -36.3 -33.3 245 64 33 8.1 4.4 | -36.2 -33.2 245 70 36 7.9 4.4
29000 -33.3 -27.9 245 62 32 8.1 4.4 | -33.9 -29.0 245 68 35 7.9 4.4
28000 -30.9 -23.6 245 60 31 8.1 4.4 | -31.5 -24.7 245 66 34 8.0 4.4
27000 -28.9 -20.0 245 56 29 6.2 3.4 | -29.2 -20.6 245 64 33 7.6 4.2
26000 -27.1 -16.8 240 53 27 6.2 3.4 | -26.9 -16.4 245 62 32 7.6 4.2
25000 -25.3 -13.5 240 49 25 6.1 3.4 | -24.6 -12.3 250 61 31 7.6 4.2
24000 -23.1 -9.6 240 46 23 7.8 4.3 | -22.5 -8.5 250 58 30 6.4 3.5
23000 -20.8 -5.4 240 43 22 7.8 4.3 | -20.6 -5.1 250 53 27 6.4 3.5
22000 -18.5 -1.3 245 40 21 7.7 4.2 | -18.7 -1.7 250 48 25 6.4 3.5
21000 -16.1 3.0 245 39 20 8.5 4.6 | -16.6 2.1 250 44 23 7.3 4.0
20000 -13.6 7.5 245 38 20 8.5 4.6 | -13.9 7.0 250 41 21 7.3 4.0
19500 -12.3 9.9 245 38 19 8.5 4.6 | -12.8 9.0 250 40 20 7.3 4.0
19000 -11.1 12.0 245 37 19 8.4 4.6 | -11.7 10.9 250 38 20 7.7 4.2
18500 -9.8 14.4 245 36 19 8.4 4.6 | -10.6 12.9 250 37 19 7.8 4.3
18000 -8.6 16.5 245 35 18 8.4 4.6 | -9.4 15.1 245 35 18 7.9 4.3
17500 -7.3 18.9 250 34 18 8.3 4.5 | -8.3 17.1 245 33 17 7.9 4.3
17000 -6.1 21.0 250 33 17 8.3 4.5 | -7.1 19.2 245 31 16 7.9 4.3
16500 -4.9 23.2 250 32 17 8.2 4.5 | -5.9 21.4 245 29 15 8.3 4.5
16000 -3.7 25.3 250 31 16 8.1 4.5 | -4.7 23.5 250 29 15 8.2 4.5
15500 -1.9 28.6 255 30 15 7.8 4.3 | -3.5 25.7 250 29 15 8.3 4.6
15000 -0.7 30.7 255 29 15 7.8 4.3 | -2.2 28.0 255 29 15 8.3 4.6
14500 0.4 32.7 255 28 14 7.8 4.3 | -1.0 30.2 255 30 15 8.4 4.6
14000 1.6 34.9 260 26 14 7.9 4.3 | 0.3 32.5 255 29 15 8.5 4.7
13500 2.8 37.0 260 25 13 7.8 4.3 | 1.5 34.7 260 27 14 8.5 4.7
13000 3.9 39.0 260 23 12 7.5 4.1 | 2.8 37.0 260 26 13 8.5 4.7
12500 5.1 41.2 260 22 11 7.4 4.1 | 4.1 39.4 260 24 12 8.5 4.7
12000 6.1 43.0 260 20 10 6.9 3.8 | 5.3 41.5 260 22 11 8.3 4.6
11500 7.2 45.0 255 18 9 6.9 3.8 | 6.6 43.9 260 20 10 8.5 4.7
11000 8.1 46.6 255 16 8 5.5 3.0 | 7.7 45.9 260 18 9 6.4 3.5
10500 8.9 48.0 250 13 7 5.4 3.0 | 8.7 47.7 260 15 8 7.4 4.0
10250 9.2 48.6 250 13 6 2.1 1.1 | 9.2 48.6 265 14 7 3.2 1.8
10000 9.3 48.7 245 12 6 1.8 1.0 | 9.3 48.7 265 12 6 3.5 1.9
9750 9.5 49.1 240 11 6 3.9 2.1 | 9.8 49.6 265 12 6 7.6 4.2
9500 9.8 49.6 235 10 5 3.0 1.6 | 10.3 50.5 260 11 6 6.8 3.7
9250 10.0 50.0 230 9 5 1.8 1.0 | 10.7 51.3 260 11 6 4.1 2.2
9000 10.0 50.0 225 9 5 -0.7 -0.4 | 10.9 51.6 260 9 5 1.2 0.6
8750 9.9 49.8 220 8 4 -2.2 -1.2 | 11.0 51.8 260 8 4 1.5 0.8
8500 9.7 49.5 210 7 4 -2.5 -1.4 | 11.1 52.0 250 8 4 1.1 0.6
8250 9.4 48.9 195 7 3 -3.3 -1.8 | 11.1 52.0 245 8 4 0.0 0.0
8000 9.2 48.6 175 6 3 -3.2 -1.7 | 11.1 52.0 230 7 3 -1.1 -0.6
7750 8.9 48.0 165 6 3 -2.8 -1.5 | 10.9 51.6 220 6 3 -4.2 -2.3
7500 8.7 47.7 155 5 2 -0.4 -0.2 | 10.5 50.9 215 6 3 -3.9 -2.2
7250 8.8 47.8 150 4 2 1.7 0.9 | 10.4 50.7 205 5 2 -0.8 -0.4
7000 8.9 48.0 135 3 1 1.0 0.5 | 10.3 50.5 190 4 2 -1.0 -0.6
6750 9.1 48.4 120 2 1 5.4 3.0 | 10.3 50.5 165 3 2 1.1 0.6
6500 9.7 49.5 115 1 0 8.5 4.6 | 10.4 50.7 180 2 1 2.8 1.5
6250 10.2 50.4 010 1 0 5.6 3.1 | 10.6 51.1 000 0 0 2.1 1.2
6000 10.7 51.3 345 2 1 10.6 5.8 | 10.8 51.4 335 2 1 2.4 1.3
5750 11.7 53.1 345 1 0 14.5 7.9 | 11.0 51.8 340 4 2 1.9 1.0
5500 12.6 54.7 335 2 1 7.8 4.3 | 11.0 51.8 330 3 2 -0.6 -0.3
________________________________________________________________________________
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