Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
288
UXUS97 KBOU 191223
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0522 MST Sunday, January 19, 2025
This forecast is for Sunday, January 19, 2025:
If the trigger temperature of 21.1 F/-6.0 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 147 ft/min (0.7 m/s)
Maximum height of thermals.................. 7893 ft MSL (2605 ft AGL)
Forecast maximum temperature................... 19.0 F/-7.7 C
Time of trigger temperature.................... None
Time of overdevelopment........................ 1200 MST
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 6478 ft MSL (1190 ft AGL)
Thermal soaring outlook for Monday 01/20....... Poor
Wave Soaring Index............................. Good
Wave Soaring Index trend (to 1700 MST).........
Height of stable layer (12-18K ft MSL)......... 16374 ft MSL (11086 ft AGL)
Weak PVA/NVA (through 1700 MST)................ Neither
Potential height of wave....................... 43720 ft MSL (38432 ft AGL)
Wave soaring outlook for Monday 01/20.......... Poor
Remarks...
Sunrise/Sunset.................... 07:16:41 / 17:04:02 MST
Total possible sunshine........... 9 hr 47 min 22 sec (587 min 22 sec)
Altitude of sun at 12:10:22 MST... 30.03 degrees
Upper air data from numerical model forecast valid on 01/19/2025 at 0500 MST
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 18995 ft MSL (13707 ft AGL)
Lifted condensation level....... 11977 ft MSL (6688 ft AGL)
Lifted index.................... +18.5
K index......................... -27.3
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 -52.4 -62.3 290 46 24 1.8 1.0 M M M M M
45000 -49.7 -57.5 300 59 30 1.8 1.0 M M M M M
40000 -49.7 -57.5 300 65 33 -0.4 -0.2 M M M M M
38000 -50.0 -58.0 300 67 34 0.0 0.0 M M M M M
36000 -52.2 -62.0 300 67 35 -4.1 -2.2 M M M M M
34000 -54.6 -66.3 300 68 35 -4.1 -2.2 M M M M M
32000 -54.7 -66.5 300 68 35 3.2 1.7 M M M M M
30000 -52.8 -63.0 300 68 35 3.2 1.8 M M M M M
29000 -51.5 -60.7 300 68 35 7.1 3.9 22.8 73.1 22.5 M M
28000 -49.4 -56.9 305 67 35 6.8 3.7 21.6 70.8 21.8 M M
27000 -47.4 -53.3 305 67 34 6.8 3.7 20.4 68.8 21.3 M M
26000 -45.3 -49.5 305 66 34 7.3 4.0 19.5 67.0 20.8 M M
25000 -43.0 -45.4 305 65 33 7.9 4.3 18.6 65.5 20.4 M M
24000 -40.6 -41.1 310 63 33 7.9 4.3 17.9 64.2 20.0 M M
23000 -38.3 -36.9 310 62 32 7.5 4.1 17.3 63.1 19.8 M M
22000 -36.2 -33.2 310 61 31 6.8 3.8 16.1 61.0 19.1 M M
21000 -34.2 -29.6 315 59 30 6.9 3.8 15.1 59.2 18.5 M M
20000 -32.2 -26.0 315 57 30 5.8 3.2 14.0 57.2 17.8 M M
19500 -31.3 -24.3 315 57 29 5.8 3.2 13.3 55.9 17.3 M M
19000 -30.4 -22.7 315 56 29 5.9 3.2 12.6 54.6 16.8 M M
18500 -29.5 -21.1 315 55 28 5.9 3.2 11.9 53.4 16.3 M M
18000 -28.7 -19.7 315 54 28 6.2 3.4 11.3 52.3 15.9 M M
17500 -27.9 -18.2 315 53 27 3.2 1.8 10.4 50.7 15.2 M M
17000 -27.4 -17.3 315 51 26 3.4 1.9 9.3 48.8 14.4 M M
16500 -26.9 -16.4 315 50 26 2.2 1.2 8.2 46.7 13.5 M M
16000 -26.6 -15.9 315 47 24 1.6 0.9 6.1 43.0 11.7 M M
15500 -26.4 -15.5 315 45 23 1.6 0.9 4.7 40.5 10.6 M M
15000 -26.1 -15.0 315 43 22 1.5 0.8 3.3 38.0 9.4 M M
14500 -25.8 -14.4 315 41 21 2.7 1.5 2.0 35.7 8.3 M M
14000 -25.4 -13.7 315 40 20 2.9 1.6 0.9 33.6 7.3 M M
13500 -24.9 -12.8 320 39 20 4.0 2.2 -0.2 31.7 6.4 M M
13000 -24.3 -11.7 320 38 20 4.3 2.3 -1.1 30.1 5.6 M M
12500 -23.6 -10.5 320 37 19 4.9 2.7 -1.9 28.5 4.8 M M
12000 -22.9 -9.2 320 37 19 5.0 2.7 -2.7 27.1 4.1 M M
11500 -22.1 -7.8 320 36 19 5.6 3.1 -3.4 25.8 3.5 M M
11000 -21.2 -6.2 320 35 18 5.6 3.0 -4.1 24.6 2.9 M M
10500 -20.3 -4.5 320 34 18 6.7 3.7 -4.7 23.6 2.3 M M
10250 -19.8 -3.6 320 34 17 7.0 3.9 -4.9 23.2 2.1 M M
10000 -19.3 -2.7 315 33 17 5.4 3.0 -5.1 22.7 1.9 M M
9750 -19.0 -2.2 315 33 17 4.0 2.2 -5.6 22.0 1.5 M M
9500 -18.6 -1.5 315 32 17 7.6 4.1 -5.9 21.3 1.1 M M
9250 -17.9 -0.2 315 31 16 10.4 5.7 -6.0 21.3 1.1 M M
9000 -17.2 1.0 310 30 16 7.2 4.0 -6.0 21.2 1.1 M M
8750 -16.8 1.8 310 30 15 5.0 2.8 -6.3 20.6 0.8 M M
8500 -16.3 2.7 310 29 15 7.6 4.1 -6.6 20.1 0.5 M M
8250 -15.7 3.7 310 28 15 7.8 4.3 -6.7 19.9 0.4 M M
8000 -15.2 4.6 305 28 14 5.7 3.1 -7.0 19.5 0.2 M M
7750 -14.8 5.4 305 27 14 4.6 2.6 -7.3 18.8 -0.2 136 0.7
7500 -14.5 5.9 305 26 13 4.2 2.3 -7.7 18.1 -0.6 118 0.6
7250 -14.2 6.4 300 24 12 2.7 1.5 -8.2 17.2 -1.1 103 0.5
7000 -14.1 6.6 300 21 11 2.1 1.2 -8.8 16.2 -1.7 91 0.5
6750 -13.9 7.0 295 17 9 1.4 0.8 -9.4 15.1 -2.2 79 0.4
6500 -13.8 7.2 285 14 7 1.4 0.7 -10.0 13.9 -2.9 69 0.4
6250 -13.7 7.3 275 11 6 1.6 0.9 -10.7 12.8 -3.5 58 0.3
6000 -13.6 7.5 255 9 5 3.8 2.1 -11.2 11.8 -4.1 46 0.2
5750 -13.4 7.9 230 9 5 -5.0 -2.8 -11.8 10.7 -4.7 34 0.2
5500 -14.6 5.7 215 6 3 -24.5 -13.4 -13.7 7.3 -6.6 63 0.3
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
01/19/2025 at 0800 MST | 01/19/2025 at 1100 MST
|
CAPE... 0.0 LI... +10.9 | CAPE... 0.0 LI... +9.7
CINH... 0.0 K Index... -18.1 | CINH... 0.0 K Index... -9.3
|
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 -52.4 -62.3 290 44 23 1.5 0.8 | -53.5 -64.3 295 56 29 1.8 1.0
45000 -50.0 -58.0 300 58 30 1.5 0.8 | -50.7 -59.3 290 60 31 1.8 1.0
40000 -49.6 -57.3 300 63 32 -0.1 -0.0 | -50.0 -58.0 295 64 33 0.2 0.1
38000 -49.7 -57.5 300 63 33 0.3 0.2 | -49.9 -57.8 295 65 33 0.4 0.2
36000 -51.7 -61.1 300 62 32 -3.9 -2.2 | -50.9 -59.6 295 63 32 -2.0 -1.1
34000 -54.1 -65.4 295 60 31 -3.9 -2.2 | -52.1 -61.8 290 60 31 -2.0 -1.1
32000 -54.8 -66.6 290 59 30 1.6 0.9 | -52.3 -62.1 290 59 30 1.4 0.8
30000 -53.8 -64.8 290 59 30 1.6 0.9 | -51.3 -60.3 290 59 30 1.4 0.8
29000 -53.0 -63.4 290 59 30 6.2 3.4 | -50.8 -59.4 290 59 30 3.8 2.1
28000 -51.3 -60.3 290 59 30 5.7 3.1 | -49.7 -57.5 290 59 30 3.5 1.9
27000 -49.6 -57.3 295 59 30 5.7 3.1 | -48.6 -55.5 290 58 30 3.5 1.9
26000 -47.9 -54.2 295 59 30 6.7 3.7 | -47.6 -53.7 290 57 30 4.0 2.2
25000 -45.4 -49.7 295 58 30 8.6 4.7 | -46.0 -50.8 295 55 28 5.6 3.1
24000 -42.8 -45.0 300 56 29 8.6 4.7 | -44.3 -47.7 295 52 27 5.6 3.1
23000 -40.2 -40.4 300 55 28 8.4 4.6 | -42.6 -44.7 295 49 25 6.7 3.7
22000 -37.8 -36.0 300 54 28 8.0 4.4 | -39.9 -39.8 295 49 25 9.2 5.0
21000 -35.4 -31.7 305 54 28 8.0 4.4 | -37.2 -35.0 295 48 25 9.2 5.1
20000 -33.2 -27.8 305 53 27 5.8 3.2 | -34.6 -30.3 295 48 24 7.2 4.0
19500 -32.3 -26.1 305 51 26 6.0 3.3 | -33.5 -28.3 295 47 24 7.3 4.0
19000 -31.3 -24.3 310 50 26 6.0 3.3 | -32.4 -26.3 295 45 23 7.4 4.0
18500 -30.4 -22.7 310 49 25 6.0 3.3 | -31.3 -24.3 300 44 23 7.4 4.1
18000 -29.5 -21.1 310 48 25 6.2 3.4 | -30.2 -22.4 300 43 22 7.7 4.2
17500 -28.7 -19.7 310 47 24 4.4 2.4 | -29.3 -20.7 300 42 22 4.6 2.5
17000 -28.0 -18.4 315 46 24 4.7 2.6 | -28.5 -19.3 300 41 21 4.9 2.7
16500 -27.2 -17.0 315 44 23 2.8 1.5 | -27.8 -18.0 300 39 20 4.4 2.4
16000 -26.7 -16.1 315 42 22 2.9 1.6 | -27.2 -17.0 305 37 19 4.2 2.3
15500 -26.3 -15.3 315 40 20 2.8 1.5 | -26.3 -15.3 305 35 18 3.8 2.1
15000 -25.9 -14.6 320 38 19 2.8 1.5 | -25.7 -14.3 310 33 17 3.8 2.1
14500 -25.4 -13.7 320 36 18 3.4 1.9 | -25.2 -13.4 310 32 16 3.5 1.9
14000 -24.9 -12.8 320 34 17 3.5 1.9 | -24.6 -12.3 315 30 15 3.4 1.9
13500 -24.4 -11.9 325 32 16 4.0 2.2 | -24.1 -11.4 315 28 14 4.1 2.3
13000 -23.8 -10.8 325 30 16 4.0 2.2 | -23.4 -10.1 320 26 13 4.2 2.3
12500 -23.1 -9.6 325 29 15 5.4 2.9 | -22.7 -8.9 320 23 12 5.6 3.1
12000 -22.2 -8.0 330 28 14 5.7 3.1 | -21.9 -7.4 320 21 11 5.8 3.2
11500 -21.4 -6.5 325 26 14 5.7 3.1 | -20.9 -5.6 315 19 10 6.9 3.8
11000 -20.6 -5.1 325 26 13 5.8 3.2 | -19.9 -3.8 315 18 9 6.9 3.8
10500 -19.8 -3.6 320 26 13 4.9 2.7 | -18.7 -1.7 310 18 9 8.3 4.5
10250 -19.4 -2.9 315 26 13 5.2 2.9 | -18.1 -0.6 310 18 10 8.7 4.8
10000 -19.0 -2.2 315 26 14 4.3 2.4 | -17.5 0.5 310 19 10 6.7 3.7
9750 -18.7 -1.7 315 27 14 3.3 1.8 | -17.1 1.2 305 20 10 3.8 2.1
9500 -18.4 -1.1 310 27 14 4.8 2.6 | -16.8 1.8 305 21 11 5.1 2.8
9250 -18.0 -0.4 310 27 14 5.8 3.2 | -16.4 2.5 300 23 12 6.9 3.8
9000 -17.6 0.3 305 27 14 5.5 3.0 | -15.9 3.4 300 25 13 4.3 2.4
8750 -17.2 1.0 305 26 13 5.7 3.1 | -15.7 3.7 300 24 13 2.5 1.4
8500 -16.8 1.8 305 25 13 6.0 3.3 | -15.4 4.3 295 23 12 4.3 2.4
8250 -16.3 2.7 305 23 12 6.2 3.4 | -15.1 4.8 290 20 10 4.8 2.7
8000 -15.8 3.6 305 21 11 6.5 3.6 | -14.7 5.5 285 18 9 5.3 2.9
7750 -15.3 4.5 305 20 10 6.4 3.5 | -14.3 6.3 280 16 8 5.3 2.9
7500 -14.9 5.2 300 18 9 5.5 3.0 | -14.0 6.8 275 13 7 4.2 2.3
7250 -14.5 5.9 300 16 8 6.6 3.6 | -13.6 7.5 260 11 6 5.4 3.0
7000 -13.9 7.0 295 14 7 7.8 4.3 | -13.1 8.4 250 9 5 6.8 3.7
6750 -13.3 8.1 290 12 6 7.2 3.9 | -12.7 9.1 235 8 4 6.4 3.5
6500 -12.9 8.8 285 10 5 3.7 2.0 | -12.1 10.2 215 7 4 8.6 4.7
6250 -12.8 9.0 270 9 4 1.2 0.7 | -11.4 11.5 210 7 4 10.6 5.8
6000 -12.7 9.1 255 8 4 1.6 0.9 | -10.6 12.9 210 7 3 10.1 5.6
5750 -12.5 9.5 235 8 4 1.9 1.1 | -9.8 14.4 205 6 3 11.5 6.3
5500 -12.6 9.3 225 6 3 -4.6 -2.5 | -8.8 16.2 205 6 3 15.8 8.7
01/19/2025 at 1400 MST | 01/19/2025 at 1700 MST
|
CAPE... 0.0 LI... +6.2 | CAPE... 0.0 LI... +5.3
CINH... 0.0 K Index... +1.6 | CINH... 0.0 K Index... +3.7
|
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 -52.6 -62.7 295 57 29 1.7 0.9 | -51.6 -60.9 295 54 28 1.1 0.6
45000 -50.0 -58.0 295 60 31 1.7 0.9 | -50.0 -58.0 295 57 29 1.1 0.6
40000 -49.3 -56.7 295 59 31 0.2 0.1 | -49.2 -56.6 295 63 32 0.3 0.2
38000 -49.2 -56.6 295 59 30 0.3 0.2 | -49.0 -56.2 295 65 34 0.5 0.3
36000 -50.0 -58.0 290 59 31 -1.6 -0.9 | -50.0 -58.0 290 64 33 -2.0 -1.1
34000 -50.9 -59.6 290 60 31 -1.6 -0.9 | -51.2 -60.2 290 63 33 -2.0 -1.1
32000 -51.6 -60.9 290 61 31 -0.6 -0.3 | -52.0 -61.6 290 60 31 -0.6 -0.3
30000 -52.0 -61.6 290 62 32 -0.6 -0.3 | -52.4 -62.3 295 54 28 -0.6 -0.3
29000 -52.0 -61.6 290 63 32 3.4 1.8 | -52.6 -62.7 295 51 26 0.1 0.1
28000 -50.9 -59.6 290 63 32 3.8 2.1 | -51.5 -60.7 295 49 25 3.4 1.9
27000 -49.7 -57.5 290 63 32 3.8 2.1 | -50.5 -58.9 300 47 24 3.4 1.9
26000 -48.6 -55.5 290 63 33 3.8 2.1 | -49.4 -56.9 300 45 23 3.3 1.8
25000 -47.0 -52.6 290 59 30 5.9 3.2 | -47.9 -54.2 300 44 23 5.6 3.1
24000 -45.2 -49.4 290 54 28 5.9 3.2 | -46.2 -51.2 295 44 23 5.6 3.1
23000 -43.4 -46.1 290 49 25 6.2 3.4 | -44.5 -48.1 295 44 23 5.8 3.2
22000 -41.0 -41.8 290 45 23 8.4 4.6 | -42.1 -43.8 290 42 22 8.8 4.8
21000 -38.6 -37.5 290 42 22 8.4 4.6 | -39.5 -39.1 290 40 21 8.8 4.8
20000 -36.1 -33.0 290 40 20 6.7 3.7 | -36.9 -34.4 285 38 20 7.2 4.0
19500 -35.2 -31.4 290 39 20 6.5 3.6 | -35.9 -32.6 285 38 19 7.1 3.9
19000 -34.2 -29.6 290 39 20 6.5 3.6 | -34.8 -30.6 290 37 19 7.1 3.9
18500 -33.2 -27.8 290 39 20 6.5 3.6 | -33.8 -28.8 290 37 19 7.1 3.9
18000 -32.2 -26.0 295 38 20 6.7 3.7 | -32.7 -26.9 295 36 19 7.3 4.0
17500 -31.4 -24.5 295 37 19 5.2 2.8 | -31.8 -25.2 295 36 19 4.6 2.5
17000 -30.6 -23.1 290 35 18 5.2 2.9 | -31.1 -24.0 295 37 19 4.7 2.6
16500 -29.8 -21.6 290 33 17 5.5 3.0 | -30.4 -22.7 300 37 19 4.9 2.7
16000 -28.9 -20.0 290 31 16 5.6 3.1 | -29.6 -21.3 300 37 19 5.1 2.8
15500 -28.1 -18.6 290 30 15 5.8 3.2 | -28.9 -20.0 295 37 19 5.0 2.8
15000 -27.2 -17.0 290 28 14 6.0 3.3 | -28.2 -18.8 295 37 19 5.0 2.7
14500 -25.9 -14.6 295 26 13 6.3 3.4 | -27.4 -17.3 295 36 18 5.3 2.9
14000 -24.9 -12.8 295 24 12 6.3 3.5 | -26.0 -14.8 295 35 18 6.8 3.7
13500 -24.0 -11.2 295 23 12 6.5 3.6 | -24.9 -12.8 295 34 17 7.6 4.2
13000 -23.0 -9.4 300 22 11 6.5 3.6 | -23.7 -10.7 295 33 17 7.9 4.3
12500 -22.0 -7.6 300 21 11 6.6 3.6 | -22.6 -8.7 295 31 16 7.7 4.2
12000 -21.0 -5.8 300 21 11 6.6 3.6 | -21.4 -6.5 295 29 15 7.6 4.2
11500 -20.1 -4.2 295 21 11 6.6 3.6 | -20.3 -4.5 295 26 13 8.1 4.5
11000 -19.1 -2.4 295 22 11 6.6 3.6 | -19.0 -2.2 295 23 12 8.4 4.6
10500 -18.0 -0.4 295 22 11 7.0 3.8 | -17.9 -0.2 295 20 10 6.1 3.3
10250 -17.5 0.5 295 22 11 7.6 4.2 | -17.4 0.7 295 18 9 7.2 4.0
10000 -17.0 1.4 295 22 11 5.2 2.9 | -17.0 1.4 295 16 8 3.3 1.8
9750 -16.7 1.9 295 22 11 5.3 2.9 | -16.8 1.8 295 15 8 4.5 2.5
9500 -16.1 3.0 295 20 10 8.1 4.5 | -16.2 2.8 290 13 6 9.2 5.0
9250 -15.5 4.1 295 18 9 8.3 4.6 | -15.6 3.9 285 11 5 8.3 4.6
9000 -14.9 5.2 295 15 8 6.7 3.7 | -15.0 5.0 280 9 4 6.9 3.8
8750 -14.5 5.9 290 13 7 5.5 3.0 | -14.5 5.9 270 7 4 6.3 3.4
8500 -14.0 6.8 290 11 6 6.9 3.8 | -14.0 6.8 260 6 3 8.2 4.5
8250 -13.5 7.7 285 9 5 7.1 3.9 | -13.4 7.9 245 5 3 8.3 4.6
8000 -13.0 8.6 275 7 4 6.1 3.3 | -12.7 9.1 230 5 2 8.3 4.6
7750 -12.6 9.3 265 5 3 5.7 3.1 | -12.1 10.2 215 5 2 8.2 4.5
7500 -12.1 10.2 240 4 2 5.8 3.2 | -11.5 11.3 205 4 2 8.0 4.4
7250 -11.7 10.9 210 3 2 6.9 3.8 | -10.9 12.4 190 4 2 7.9 4.4
7000 -11.1 12.0 190 3 1 7.9 4.4 | -10.3 13.5 175 4 2 7.8 4.3
6750 -10.5 13.1 170 3 1 8.3 4.6 | -9.7 14.5 160 3 2 8.0 4.4
6500 -9.9 14.2 165 3 1 9.5 5.2 | -9.1 15.6 140 3 2 8.4 4.6
6250 -9.1 15.6 160 2 1 9.9 5.5 | -8.5 16.7 130 3 1 8.7 4.8
6000 -8.4 16.9 160 2 1 9.7 5.3 | -7.9 17.8 115 2 1 8.9 4.9
5750 -7.6 18.3 160 2 1 10.8 5.9 | -7.2 19.0 100 2 1 8.3 4.5
5500 -6.7 19.9 155 2 1 14.0 7.7 | -6.7 19.9 085 2 1 6.4 3.5
________________________________________________________________________________
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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