Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
746
UXUS97 KBOU 221221
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0620 MDT Wednesday, May 22, 2024
This forecast is for Wednesday, May 22, 2024:
If the trigger temperature of 55.4 F/13.0 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1203 ft/min (6.1 m/s)
Maximum height of thermals.................. 19440 ft MSL (14104 ft AGL)
Forecast maximum temperature................... 74.0 F/23.8 C
Time of trigger temperature.................... 0930 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................. 16632 ft MSL (11296 ft AGL)
Thermal soaring outlook for Thursday 05/23..... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 36818 ft MSL (31482 ft AGL)
Wave soaring outlook for Thursday 05/23........ Good
Remarks... None
Sunrise/Sunset.................... 05:38:27 / 20:14:01 MDT
Total possible sunshine........... 14 hr 35 min 34 sec (875 min 34 sec)
Altitude of sun at 12:56:14 MDT... 70.81 degrees
Upper air data from numerical model forecast valid on 05/22/2024 at 0600 MDT
Freezing level.................. 9764 ft MSL (4428 ft AGL)
Convective condensation level... 18088 ft MSL (12752 ft AGL)
Lifted condensation level....... 18937 ft MSL (13601 ft AGL)
Lifted index.................... -0.0
K index......................... -13.1
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 -52.2 -62.0 255 41 21 1.1 0.6 M M M M M
45000 -50.6 -59.1 260 50 26 -1.3 -0.7 M M M M M
40000 -52.0 -61.6 260 67 35 -1.0 -0.5 M M M M M
38000 -52.7 -62.9 265 70 36 -1.3 -0.7 M M M M M
36000 -53.5 -64.3 265 70 36 -1.3 -0.7 M M M M M
34000 -53.7 -64.7 270 70 36 7.5 4.1 M M M M M
32000 -49.1 -56.4 270 64 33 6.9 3.8 M M M M M
30000 -44.7 -48.5 270 59 30 8.3 4.5 30.8 87.5 5.6 M M
29000 -42.3 -44.1 270 58 30 8.3 4.6 30.1 86.3 5.2 M M
28000 -39.8 -39.6 270 57 29 8.3 4.6 29.6 85.3 4.8 M M
27000 -37.3 -35.1 270 55 29 8.1 4.4 29.2 84.6 4.6 M M
26000 -34.9 -30.8 275 53 27 8.0 4.4 28.4 83.1 4.0 M M
25000 -32.5 -26.5 275 51 26 8.0 4.4 27.7 81.9 3.5 M M
24000 -30.1 -22.2 275 49 25 7.9 4.3 27.2 80.9 3.1 M M
23000 -27.8 -18.0 280 46 24 7.7 4.2 26.3 79.4 2.4 M M
22000 -25.5 -13.9 280 42 22 7.7 4.3 25.6 78.1 1.9 M M
21000 -23.2 -9.8 285 39 20 7.3 4.0 25.0 76.9 1.3 M M
20000 -21.0 -5.8 285 35 18 7.2 3.9 24.0 75.1 0.5 M M
19500 -20.0 -4.0 285 33 17 7.2 3.9 23.5 74.3 0.1 M M
19000 -18.9 -2.0 285 32 16 7.1 3.9 23.1 73.6 -0.2 1171 5.9
18500 -17.8 -0.0 290 30 15 6.7 3.7 22.7 72.9 -0.6 1124 5.7
18000 -16.5 2.3 290 27 14 6.0 3.3 21.7 71.1 -1.4 1061 5.4
17500 -15.5 4.1 290 26 13 5.8 3.2 21.1 70.0 -2.0 1019 5.2
17000 -14.7 5.5 290 24 12 5.5 3.0 20.4 68.7 -2.7 980 5.0
16500 -13.9 7.0 290 22 11 5.6 3.1 19.7 67.4 -3.3 940 4.8
16000 -13.0 8.6 290 20 10 6.3 3.4 19.0 66.2 -3.9 899 4.6
15500 -12.1 10.2 295 18 9 6.3 3.4 18.4 65.2 -4.5 856 4.3
15000 -11.2 11.8 295 17 9 5.7 3.1 17.8 64.0 -5.1 815 4.1
14500 -10.4 13.3 295 16 8 5.6 3.1 17.1 62.8 -5.7 775 3.9
14000 -9.5 14.9 295 15 7 6.4 3.5 16.5 61.7 -6.3 734 3.7
13500 -8.5 16.7 295 14 7 6.6 3.6 15.9 60.7 -6.9 690 3.5
13000 -7.5 18.5 300 13 7 7.3 4.0 15.5 59.8 -7.4 645 3.3
12500 -6.4 20.5 300 12 6 7.7 4.2 15.1 59.2 -7.7 597 3.0
12000 -5.2 22.6 300 12 6 8.2 4.5 14.8 58.7 -8.1 547 2.8
11500 -4.0 24.8 300 12 6 8.4 4.6 14.6 58.3 -8.3 495 2.5
11000 -2.7 27.1 300 13 7 8.5 4.7 14.4 57.9 -8.6 443 2.2
10500 -1.5 29.3 300 14 7 9.3 5.1 14.2 57.5 -8.9 390 2.0
10250 -0.8 30.6 300 15 8 5.2 2.9 14.1 57.3 -9.0 364 1.9
10000 -0.6 30.9 300 15 8 5.1 2.8 13.6 56.4 -9.5 349 1.8
9750 0.0 32.0 300 15 8 9.0 4.9 13.4 56.2 -9.6 324 1.6
9500 0.6 33.1 295 15 8 8.0 4.4 13.3 56.0 -9.8 299 1.5
9250 1.2 34.2 295 15 8 8.2 4.5 13.2 55.8 -10.0 273 1.4
9000 1.8 35.2 290 15 8 8.1 4.4 13.1 55.5 -10.1 248 1.3
8750 2.4 36.3 290 15 8 8.3 4.6 12.9 55.3 -10.3 223 1.1
8500 3.0 37.4 290 14 7 8.5 4.7 12.8 55.1 -10.4 197 1.0
8250 3.6 38.5 285 14 7 8.1 4.4 12.7 54.9 -10.6 171 0.9
8000 4.2 39.6 285 14 7 7.7 4.2 12.6 54.7 -10.8 147 0.7
7750 4.7 40.5 285 14 7 7.5 4.1 12.4 54.4 -11.0 123 0.6
7500 5.3 41.5 280 13 7 7.2 4.0 12.2 54.0 -11.2 100 0.5
7250 5.8 42.4 275 12 6 7.2 3.9 12.0 53.7 -11.4 77 0.4
7000 6.3 43.3 275 11 6 6.5 3.6 11.8 53.3 -11.7 54 0.3
6750 6.8 44.2 270 11 6 8.6 4.7 11.6 52.9 -11.9 31 0.2
6500 7.4 45.3 260 10 5 5.3 2.9 11.5 52.7 -12.1 5 0.0
6250 7.5 45.5 250 10 5 -0.1 -0.0 10.9 51.6 -12.7 M M
6000 7.6 45.7 245 9 5 2.6 1.4 10.2 50.4 -13.5 M M
5750 7.6 45.7 235 9 5 -4.5 -2.5 9.6 49.2 -14.2 M M
5500 6.4 43.5 230 8 4 -30.2 -16.5 7.6 45.7 -16.2 8 0.0
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/22/2024 at 0900 MDT | 05/22/2024 at 1200 MDT
|
CAPE... 0.0 LI... +5.4 | CAPE... 0.0 LI... +4.6
CINH... -0.1 K Index... -13.5 | CINH... -0.1 K Index... -8.2
|
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 -62.3 250 41 21 1.3 0.7 | -53.2 -63.8 250 44 23 1.7 0.9
45000 -50.6 -59.1 260 47 24 -2.7 -1.5 | -50.9 -59.6 255 50 26 -2.9 -1.6
40000 -53.9 -65.0 260 69 36 -2.2 -1.2 | -54.6 -66.3 260 67 35 -2.5 -1.4
38000 -54.5 -66.1 260 72 37 0.4 0.2 | -55.0 -67.0 260 68 35 1.0 0.5
36000 -54.2 -65.6 265 68 35 0.4 0.2 | -54.4 -65.9 260 64 33 1.0 0.5
34000 -53.4 -64.1 265 64 33 8.2 4.5 | -53.1 -63.6 255 59 31 8.1 4.5
32000 -48.3 -54.9 270 60 31 7.5 4.1 | -48.5 -55.3 260 57 29 7.7 4.2
30000 -43.8 -46.8 270 56 29 7.7 4.2 | -43.3 -45.9 260 54 28 7.8 4.3
29000 -41.5 -42.7 265 55 28 7.7 4.2 | -40.9 -41.6 260 52 27 7.8 4.3
28000 -39.2 -38.6 265 53 27 7.7 4.2 | -38.6 -37.5 260 51 26 7.8 4.3
27000 -36.9 -34.4 265 52 27 7.6 4.2 | -36.3 -33.3 260 49 25 7.7 4.2
26000 -34.6 -30.3 265 50 26 7.6 4.1 | -34.0 -29.2 260 47 24 7.7 4.2
25000 -32.4 -26.3 265 48 24 7.6 4.2 | -31.7 -25.1 260 45 23 7.7 4.2
24000 -30.1 -22.2 265 46 23 7.7 4.2 | -29.4 -20.9 260 43 22 7.8 4.3
23000 -27.8 -18.0 265 43 22 7.8 4.3 | -27.0 -16.6 260 40 21 7.8 4.3
22000 -25.4 -13.7 270 40 21 7.8 4.3 | -24.7 -12.5 260 37 19 7.8 4.3
21000 -23.1 -9.6 270 37 19 7.6 4.2 | -22.3 -8.1 260 35 18 7.9 4.3
20000 -20.8 -5.4 270 35 18 7.6 4.2 | -20.0 -4.0 260 33 17 7.9 4.3
19500 -19.7 -3.5 270 34 17 7.6 4.2 | -18.8 -1.8 260 32 16 7.9 4.3
19000 -18.5 -1.3 270 32 17 7.6 4.2 | -17.6 0.3 260 31 16 7.9 4.3
18500 -17.4 0.7 270 31 16 7.5 4.1 | -16.4 2.5 260 30 15 7.6 4.2
18000 -16.3 2.7 270 30 15 7.5 4.1 | -15.3 4.5 260 29 15 7.4 4.1
17500 -14.6 5.7 270 28 14 7.2 3.9 | -14.2 6.4 260 29 15 7.4 4.1
17000 -13.5 7.7 270 27 14 7.0 3.8 | -13.2 8.2 260 29 15 6.9 3.8
16500 -12.5 9.5 270 25 13 7.0 3.8 | -11.6 11.1 265 28 14 6.9 3.8
16000 -11.5 11.3 270 24 12 6.8 3.7 | -10.6 12.9 265 27 14 6.8 3.8
15500 -10.4 13.3 270 23 12 6.8 3.7 | -9.6 14.7 265 27 14 6.8 3.7
15000 -9.4 15.1 270 21 11 6.7 3.7 | -8.5 16.7 265 26 13 7.3 4.0
14500 -8.4 16.9 270 20 10 6.7 3.7 | -7.5 18.5 265 24 13 7.2 4.0
14000 -7.5 18.5 270 18 10 6.3 3.5 | -6.4 20.5 260 23 12 7.4 4.1
13500 -6.5 20.3 270 17 9 6.3 3.5 | -5.3 22.5 260 21 11 7.4 4.1
13000 -5.6 21.9 270 15 8 6.4 3.5 | -4.2 24.4 255 19 10 7.3 4.0
12500 -4.6 23.7 270 14 7 6.5 3.5 | -3.1 26.4 250 18 9 7.3 4.0
12000 -3.7 25.3 275 12 6 6.9 3.8 | -2.0 28.4 245 16 8 7.1 3.9
11500 -2.6 27.3 275 11 6 7.2 4.0 | -1.0 30.2 235 15 7 7.0 3.9
11000 -1.5 29.3 275 10 5 7.0 3.9 | 0.0 32.0 225 14 7 6.3 3.5
10500 -0.5 31.1 275 8 4 7.6 4.2 | 0.9 33.6 215 13 7 5.0 2.8
10250 -0.0 32.0 275 8 4 4.4 2.4 | 1.4 34.5 210 13 6 9.4 5.2
10000 0.2 32.4 280 8 4 4.9 2.7 | 2.2 36.0 200 12 6 10.6 5.8
9750 0.8 33.4 275 8 4 8.3 4.6 | 2.8 37.0 195 12 6 6.8 3.7
9500 1.3 34.3 270 7 4 7.7 4.2 | 3.3 37.9 190 12 6 8.1 4.5
9250 1.9 35.4 265 6 3 6.8 3.7 | 3.9 39.0 185 12 6 6.7 3.6
9000 2.3 36.1 260 6 3 6.0 3.3 | 4.4 39.9 175 12 6 7.6 4.2
8750 2.8 37.0 255 6 3 7.4 4.1 | 5.0 41.0 175 12 6 9.7 5.3
8500 3.4 38.1 245 6 3 8.2 4.5 | 5.7 42.3 170 11 6 9.8 5.4
8250 3.9 39.0 230 5 3 7.0 3.8 | 6.4 43.5 170 11 6 9.1 5.0
8000 4.4 39.9 220 5 3 6.1 3.3 | 7.1 44.8 165 11 6 8.7 4.8
7750 4.9 40.8 215 6 3 7.8 4.3 | 7.8 46.0 165 11 6 10.2 5.6
7500 5.5 41.9 205 6 3 8.3 4.6 | 8.6 47.5 165 11 6 10.7 5.9
7250 6.1 43.0 195 7 4 7.2 3.9 | 9.3 48.7 165 11 6 8.8 4.8
7000 6.6 43.9 190 8 4 6.2 3.4 | 9.9 49.8 165 11 5 7.4 4.0
6750 7.1 44.8 185 9 4 9.5 5.2 | 10.5 50.9 165 11 5 11.3 6.2
6500 7.9 46.2 185 9 5 9.7 5.3 | 11.5 52.7 165 10 5 12.8 7.0
6250 8.4 47.1 185 9 4 7.1 3.9 | 12.3 54.1 165 10 5 10.7 5.9
6000 8.9 48.0 185 8 4 7.0 3.8 | 13.1 55.6 160 10 5 10.3 5.6
5750 9.4 48.9 180 8 4 9.5 5.2 | 13.9 57.0 160 9 5 11.7 6.4
5500 10.3 50.5 185 6 3 17.1 9.4 | 15.1 59.2 160 9 5 21.1 11.6
05/22/2024 at 1500 MDT | 05/22/2024 at 1800 MDT
|
CAPE... +2.2 LI... +0.7 | CAPE... +11.9 LI... +1.0
CINH... -13.8 K Index... +12.9 | CINH... -63.7 K Index... +18.7
|
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 -53.5 -64.3 250 46 24 1.0 0.6 | -52.9 -63.2 260 44 23 1.4 0.8
45000 -52.2 -62.0 255 51 26 -1.9 -1.0 | -51.0 -59.8 260 51 26 -3.2 -1.7
40000 -54.7 -66.5 260 56 29 -1.6 -0.9 | -55.1 -67.2 275 59 30 -2.8 -1.5
38000 -54.7 -66.5 260 58 30 1.2 0.7 | -54.9 -66.8 280 61 31 2.8 1.5
36000 -53.9 -65.0 255 60 31 1.2 0.7 | -53.2 -63.8 285 62 32 2.8 1.5
34000 -52.5 -62.5 255 61 32 7.9 4.3 | -51.2 -60.2 285 63 32 6.2 3.4
32000 -47.3 -53.1 260 58 30 7.6 4.2 | -47.1 -52.8 275 58 30 6.0 3.3
30000 -42.7 -44.9 260 55 28 7.8 4.3 | -43.3 -45.9 265 56 29 7.1 3.9
29000 -40.4 -40.7 260 54 28 7.8 4.3 | -41.2 -42.2 265 55 28 7.1 3.9
28000 -38.1 -36.6 260 54 28 7.8 4.3 | -39.0 -38.2 260 53 28 7.1 3.9
27000 -35.7 -32.3 260 53 27 7.5 4.1 | -36.9 -34.4 260 52 27 8.0 4.4
26000 -33.5 -28.3 260 52 27 7.5 4.1 | -34.4 -29.9 255 50 26 8.1 4.5
25000 -31.2 -24.2 260 51 26 7.5 4.1 | -32.0 -25.6 255 48 24 8.1 4.5
24000 -29.0 -20.2 260 50 26 7.3 4.0 | -29.6 -21.3 255 45 23 8.4 4.6
23000 -26.9 -16.4 255 48 25 7.0 3.9 | -27.0 -16.6 250 43 22 8.7 4.8
22000 -24.8 -12.6 255 46 24 7.0 3.9 | -24.4 -11.9 250 41 21 8.7 4.8
21000 -22.7 -8.9 255 43 22 7.7 4.2 | -21.8 -7.2 245 39 20 8.5 4.7
20000 -20.4 -4.7 250 40 21 7.8 4.3 | -19.3 -2.7 245 37 19 8.5 4.7
19500 -19.2 -2.6 250 38 20 7.8 4.3 | -18.1 -0.6 245 37 19 8.5 4.7
19000 -18.1 -0.6 250 36 19 7.8 4.3 | -16.8 1.8 240 36 18 8.6 4.7
18500 -16.9 1.6 245 35 18 8.2 4.5 | -15.5 4.1 240 35 18 8.3 4.5
18000 -15.7 3.7 245 33 17 8.3 4.6 | -14.3 6.3 240 34 18 8.2 4.5
17500 -14.5 5.9 245 32 16 8.3 4.6 | -13.1 8.4 240 34 17 8.2 4.5
17000 -12.6 9.3 245 30 16 8.4 4.6 | -11.9 10.6 240 33 17 8.0 4.4
16500 -11.3 11.7 240 29 15 8.6 4.7 | -10.2 13.6 240 31 16 8.0 4.4
16000 -10.0 14.0 240 28 15 9.2 5.1 | -9.0 15.8 240 30 16 7.8 4.3
15500 -8.6 16.5 240 27 14 9.2 5.1 | -7.9 17.8 240 29 15 7.8 4.3
15000 -7.3 18.9 240 26 13 8.9 4.9 | -6.7 19.9 240 28 15 8.4 4.6
14500 -5.9 21.4 235 25 13 9.0 4.9 | -5.4 22.3 245 27 14 8.3 4.6
14000 -4.6 23.7 235 24 12 9.0 4.9 | -4.1 24.6 245 25 13 9.2 5.0
13500 -3.3 26.1 235 23 12 9.0 4.9 | -2.8 27.0 245 24 12 9.2 5.1
13000 -1.9 28.6 230 22 11 8.7 4.8 | -1.4 29.5 245 23 12 9.2 5.1
12500 -0.7 30.7 230 20 10 8.5 4.7 | 0.0 32.0 250 22 11 9.2 5.1
12000 0.6 33.1 225 19 10 8.5 4.7 | 1.4 34.5 250 20 11 9.3 5.1
11500 1.8 35.2 220 16 8 8.4 4.6 | 2.8 37.0 250 19 10 9.4 5.1
11000 3.1 37.6 210 14 7 7.7 4.2 | 4.2 39.6 250 18 9 8.6 4.7
10500 4.2 39.6 200 11 6 6.1 3.4 | 5.4 41.7 255 18 9 7.0 3.8
10250 4.7 40.5 195 10 5 11.5 6.3 | 6.0 42.8 255 17 9 12.1 6.6
10000 5.8 42.4 195 10 5 13.2 7.2 | 7.1 44.8 255 16 8 13.1 7.2
9750 6.5 43.7 195 10 5 8.8 4.8 | 7.8 46.0 255 15 8 8.5 4.7
9500 7.2 45.0 195 10 5 10.4 5.7 | 8.6 47.5 260 15 8 10.1 5.5
9250 8.0 46.4 190 9 5 8.4 4.6 | 9.3 48.7 260 14 7 8.6 4.7
9000 8.5 47.3 180 7 4 8.9 4.9 | 9.9 49.8 260 15 8 8.9 4.9
8750 9.3 48.7 180 8 4 10.8 5.9 | 10.6 51.1 265 14 7 10.2 5.6
8500 10.1 50.2 180 8 4 10.5 5.7 | 11.4 52.5 265 13 7 10.1 5.5
8250 10.9 51.6 185 8 4 9.9 5.4 | 12.1 53.8 270 12 6 9.5 5.2
8000 11.6 52.9 175 7 4 9.4 5.1 | 12.8 55.0 275 12 6 8.8 4.8
7750 12.3 54.1 170 6 3 10.0 5.5 | 13.5 56.3 275 12 6 9.3 5.1
7500 13.1 55.6 175 7 3 10.8 5.9 | 14.2 57.6 280 11 6 9.9 5.4
7250 13.9 57.0 180 7 4 8.9 4.9 | 14.9 58.8 285 10 5 8.6 4.7
7000 14.4 57.9 170 6 3 7.4 4.0 | 15.5 59.9 285 11 6 7.5 4.1
6750 15.1 59.2 165 6 3 10.8 5.9 | 16.1 61.0 290 11 6 10.0 5.5
6500 16.0 60.8 170 6 3 12.5 6.9 | 16.9 62.4 290 10 5 11.3 6.2
6250 16.9 62.4 170 6 3 10.7 5.9 | 17.7 63.9 295 10 5 9.8 5.4
6000 17.6 63.7 165 5 3 10.4 5.7 | 18.4 65.1 295 10 5 9.1 5.0
5750 18.4 65.1 160 5 2 9.6 5.2 | 19.1 66.4 295 11 5 9.5 5.2
5500 19.2 66.6 170 5 3 15.4 8.4 | 19.8 67.6 295 9 5 11.4 6.2
________________________________________________________________________________
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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