Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
896
UXUS97 KBOU 060117
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1916 MDT Sunday, May 5, 2024
This forecast is for Monday, May 6, 2024:
If the trigger temperature of 51.1 F/10.6 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 406 ft/min (2.1 m/s)
Maximum height of thermals.................. 13314 ft MSL (8050 ft AGL)
Forecast maximum temperature................... 61.0 F/16.6 C
Time of trigger temperature.................... 0845 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Overcast opaque high
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 11179 ft MSL (5915 ft AGL)
Thermal soaring outlook for Tuesday 05/07...... Poor
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....................... 24500 ft MSL (19236 ft AGL)
Wave soaring outlook for Tuesday 05/07......... Poor
Remarks...
Sunrise/Sunset.................... 05:53:01 / 19:59:05 MDT
Total possible sunshine........... 14 hr 6 min 5 sec (846 min 5 sec)
Altitude of sun at 12:56:03 MDT... 67.05 degrees
Upper air data from numerical model forecast valid on 05/06/2024 at 0600 MDT
Freezing level.................. 8699 ft MSL (3435 ft AGL)
Convective condensation level... 18416 ft MSL (13152 ft AGL)
Lifted condensation level....... 15535 ft MSL (10271 ft AGL)
Lifted index.................... +6.4
K index......................... -13.2
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 -52.9 -63.2 235 35 18 2.0 1.1 M M M M M
45000 -49.9 -57.8 230 51 26 0.9 0.5 M M M M M
40000 -50.2 -58.4 215 60 31 -0.2 -0.1 M M M M M
38000 -50.2 -58.4 210 66 34 0.1 0.1 M M M M M
36000 -50.2 -58.4 200 74 38 0.1 0.1 M M M M M
34000 -50.1 -58.2 195 83 43 2.3 1.3 M M M M M
32000 -45.7 -50.3 195 82 42 6.7 3.7 M M M M M
30000 -41.6 -42.9 190 80 41 7.5 4.1 34.9 94.9 14.1 M M
29000 -39.4 -38.9 195 79 41 7.5 4.1 33.9 93.0 13.5 M M
28000 -37.2 -35.0 195 78 40 7.5 4.1 33.0 91.3 13.0 M M
27000 -34.9 -30.8 200 77 40 7.5 4.1 32.2 90.0 12.5 M M
26000 -32.7 -26.9 200 77 40 7.3 4.0 31.2 88.2 12.0 M M
25000 -30.5 -22.9 200 78 40 7.3 4.0 30.3 86.5 11.3 M M
24000 -28.3 -18.9 205 79 41 7.3 4.0 29.4 84.9 10.8 M M
23000 -26.1 -15.0 205 79 41 7.5 4.1 28.5 83.4 10.2 M M
22000 -23.8 -10.8 205 78 40 7.5 4.1 27.7 81.8 9.6 M M
21000 -21.6 -6.9 210 77 40 7.5 4.1 26.9 80.5 9.1 M M
20000 -19.4 -2.9 210 75 39 7.1 3.9 26.0 78.9 8.4 M M
19500 -18.3 -0.9 210 73 38 7.1 3.9 25.5 78.0 8.0 M M
19000 -17.3 0.9 210 72 37 7.1 3.9 25.1 77.2 7.7 M M
18500 -16.2 2.8 215 70 36 7.1 3.9 24.7 76.4 7.4 M M
18000 -15.1 4.8 215 69 35 6.1 3.3 24.3 75.7 7.0 M M
17500 -14.4 6.1 215 66 34 5.2 2.8 23.4 74.2 6.4 M M
17000 -13.6 7.5 215 64 33 5.2 2.9 22.6 72.8 5.7 M M
16500 -13.0 8.6 220 61 31 3.6 2.0 21.7 71.1 4.9 M M
16000 -12.4 9.7 220 58 30 3.7 2.0 20.7 69.2 4.0 M M
15500 -11.8 10.8 225 54 28 4.3 2.4 19.7 67.5 3.2 M M
15000 -10.8 12.6 230 49 25 4.3 2.4 18.4 65.1 2.0 M M
14500 -10.1 13.8 230 45 23 6.0 3.3 17.6 63.7 1.3 M M
14000 -9.2 15.4 235 42 22 6.0 3.3 17.0 62.6 0.7 M M
13500 -8.3 17.1 235 40 20 5.5 3.0 16.3 61.4 0.1 M M
13000 -7.5 18.5 240 39 20 5.4 3.0 15.6 60.1 -0.6 575 2.9
12500 -6.7 19.9 245 38 20 5.2 2.9 14.9 58.8 -1.2 536 2.7
12000 -6.0 21.2 250 37 19 5.1 2.8 14.1 57.5 -2.0 499 2.5
11500 -5.2 22.6 255 37 19 5.8 3.2 13.4 56.2 -2.7 462 2.3
11000 -4.3 24.3 260 38 19 6.1 3.4 12.8 55.1 -3.3 420 2.1
10500 -3.5 25.7 260 39 20 5.2 2.9 12.3 54.1 -3.9 379 1.9
10250 -3.1 26.4 260 39 20 4.8 2.6 11.9 53.3 -4.3 361 1.8
10000 -2.7 27.1 260 39 20 6.6 3.6 11.5 52.8 -4.6 342 1.7
9750 -2.2 28.0 260 39 20 7.5 4.1 11.3 52.4 -4.8 318 1.6
9500 -1.7 28.9 260 39 20 6.9 3.8 11.1 52.0 -5.1 295 1.5
9250 -1.2 29.8 265 38 20 6.5 3.6 10.9 51.6 -5.3 273 1.4
9000 -0.7 30.7 265 38 19 7.6 4.2 10.7 51.2 -5.6 251 1.3
8750 -0.0 32.0 265 36 19 8.8 4.9 10.6 51.0 -5.7 225 1.1
8500 0.6 33.1 265 35 18 8.7 4.8 10.5 50.9 -5.8 198 1.0
8250 1.2 34.2 265 35 18 8.3 4.5 10.4 50.7 -5.9 172 0.9
8000 1.9 35.4 265 34 17 9.7 5.3 10.3 50.6 -6.0 145 0.7
7750 2.6 36.7 260 33 17 10.5 5.7 10.4 50.7 -6.0 114 0.6
7500 3.4 38.1 260 32 16 9.4 5.1 10.4 50.7 -6.0 85 0.4
7250 4.1 39.4 260 31 16 10.4 5.7 10.4 50.7 -6.0 56 0.3
7000 4.8 40.6 260 30 16 7.5 4.1 10.4 50.7 -6.1 27 0.1
6750 5.3 41.5 260 30 15 8.1 4.5 10.1 50.2 -6.3 5 0.0
6500 6.1 43.0 260 28 14 11.2 6.1 10.2 50.3 -6.3 M M
6250 6.9 44.4 255 26 14 11.2 6.1 10.3 50.5 -6.2 M M
6000 7.7 45.9 255 25 13 7.3 4.0 10.3 50.5 -6.2 M M
5750 8.0 46.4 250 23 12 3.7 2.0 9.9 49.8 -6.7 M M
5500 8.4 47.1 245 18 10 9.6 5.3 9.6 49.3 -7.0 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/06/2024 at 0900 MDT | 05/06/2024 at 1200 MDT
|
CAPE... 0.0 LI... +2.4 | CAPE... +121.0 LI... -0.6
CINH... 0.0 K Index... +0.8 | CINH... -3.6 K Index... +12.1
|
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 -51.5 -60.7 235 26 13 3.2 1.7 | -51.3 -60.3 230 25 13 3.6 2.0
45000 -46.8 -52.2 235 33 17 2.6 1.4 | -45.9 -50.6 255 21 11 2.3 1.3
40000 -44.3 -47.7 230 50 26 1.6 0.9 | -44.6 -48.3 235 51 26 0.8 0.5
38000 -44.0 -47.2 225 56 29 -1.3 -0.7 | -43.8 -46.8 235 56 29 2.1 1.2
36000 -44.8 -48.6 215 63 32 -1.2 -0.7 | -42.5 -44.5 235 51 26 2.1 1.2
34000 -45.5 -49.9 205 72 37 -1.5 -0.8 | -41.2 -42.2 235 45 23 2.1 1.2
32000 -43.5 -46.3 200 73 38 3.9 2.1 | -39.9 -39.8 235 44 23 2.2 1.2
30000 -41.2 -42.2 195 74 38 3.7 2.0 | -38.6 -37.5 235 43 22 2.2 1.2
29000 -39.7 -39.5 195 74 38 5.4 3.0 | -38.0 -36.4 235 42 21 2.0 1.1
28000 -37.7 -35.9 195 74 38 5.4 3.0 | -37.4 -35.3 235 40 20 2.0 1.1
27000 -36.1 -33.0 195 75 38 5.4 3.0 | -36.8 -34.2 235 38 19 2.0 1.1
26000 -34.5 -30.1 195 73 38 4.8 2.6 | -36.3 -33.3 235 35 18 -0.2 -0.1
25000 -33.1 -27.6 195 70 36 4.8 2.6 | -36.3 -33.3 235 33 17 -0.0 -0.0
24000 -31.6 -24.9 195 67 35 4.8 2.7 | -36.3 -33.3 235 30 15 -0.0 -0.0
23000 -30.3 -22.5 195 63 32 3.3 1.8 | -36.0 -32.8 235 27 14 5.5 3.0
22000 -29.3 -20.7 200 55 28 3.5 1.9 | -34.4 -29.9 240 22 11 5.2 2.9
21000 -28.2 -18.8 205 48 25 3.6 2.0 | -32.9 -27.2 255 17 9 5.3 2.9
20000 -27.0 -16.6 210 41 21 5.3 2.9 | -30.9 -23.6 265 15 8 8.6 4.7
19500 -26.2 -15.2 210 37 19 5.3 2.9 | -29.6 -21.3 270 16 8 8.6 4.7
19000 -25.4 -13.7 215 35 18 5.3 2.9 | -28.3 -18.9 275 16 8 8.6 4.7
18500 -24.6 -12.3 225 32 16 5.3 2.9 | -27.0 -16.6 280 17 9 8.6 4.7
18000 -23.8 -10.8 230 30 15 5.6 3.1 | -25.7 -14.3 285 17 9 8.6 4.7
17500 -22.9 -9.2 235 28 14 6.3 3.4 | -24.4 -11.9 290 19 10 8.5 4.7
17000 -22.0 -7.6 245 26 14 6.1 3.3 | -23.2 -9.8 290 21 11 8.5 4.7
16500 -20.9 -5.6 250 26 13 7.9 4.3 | -21.9 -7.4 290 23 12 8.8 4.8
16000 -19.8 -3.6 255 26 13 7.8 4.3 | -20.6 -5.1 290 25 13 8.7 4.8
15500 -18.6 -1.5 265 27 14 7.8 4.3 | -19.3 -2.7 290 27 14 8.8 4.8
15000 -17.5 0.5 270 28 14 7.7 4.2 | -18.0 -0.4 290 29 15 8.8 4.8
14500 -16.3 2.7 270 29 15 7.7 4.2 | -16.7 1.9 290 31 16 8.8 4.8
14000 -14.6 5.7 275 32 16 7.6 4.1 | -15.4 4.3 290 33 17 8.9 4.9
13500 -13.5 7.7 275 33 17 7.5 4.1 | -14.0 6.8 285 34 18 8.8 4.8
13000 -12.4 9.7 275 35 18 7.5 4.1 | -12.1 10.2 285 36 18 8.5 4.7
12500 -11.3 11.7 275 36 19 8.0 4.4 | -10.9 12.4 285 36 19 8.8 4.8
12000 -10.1 13.8 275 38 19 8.1 4.5 | -9.6 14.7 280 36 19 8.8 4.8
11500 -8.9 16.0 275 39 20 8.2 4.5 | -8.2 17.2 280 36 19 9.3 5.1
11000 -7.7 18.1 275 40 21 8.3 4.5 | -6.8 19.8 280 36 19 9.6 5.2
10500 -6.5 20.3 275 41 21 7.2 3.9 | -5.6 21.9 280 36 19 7.1 3.9
10250 -6.0 21.2 275 41 21 6.7 3.7 | -5.0 23.0 280 36 19 7.0 3.8
10000 -5.4 22.3 275 41 21 9.2 5.0 | -4.4 24.1 280 36 19 11.3 6.2
9750 -4.6 23.7 275 41 21 10.2 5.6 | -3.5 25.7 280 37 19 11.6 6.4
9500 -4.0 24.8 270 40 21 8.7 4.7 | -2.8 27.0 280 36 19 8.6 4.7
9250 -3.3 26.1 270 39 20 8.2 4.5 | -2.1 28.2 280 36 19 8.2 4.5
9000 -2.7 27.1 270 38 19 9.3 5.1 | -1.5 29.3 280 36 18 10.6 5.8
8750 -2.0 28.4 270 37 19 10.0 5.5 | -0.6 30.9 275 36 18 11.4 6.3
8500 -1.3 29.7 270 36 19 9.4 5.1 | 0.2 32.4 275 35 18 9.3 5.1
8250 -0.6 30.9 270 35 18 9.2 5.1 | 0.9 33.6 275 35 18 10.4 5.7
8000 0.1 32.2 270 33 17 9.9 5.4 | 1.6 34.9 275 34 18 8.2 4.5
7750 0.9 33.6 270 33 17 10.4 5.7 | 2.2 36.0 275 34 17 8.9 4.9
7500 1.6 34.9 265 32 16 9.7 5.3 | 3.0 37.4 275 33 17 11.1 6.1
7250 2.4 36.3 265 31 16 10.8 5.9 | 3.8 38.8 275 32 17 11.8 6.5
7000 3.1 37.6 265 30 15 7.2 4.0 | 4.6 40.3 275 32 16 7.0 3.8
6750 3.6 38.5 265 28 15 8.3 4.6 | 5.0 41.0 275 31 16 8.1 4.4
6500 4.5 40.1 265 27 14 12.6 6.9 | 5.9 42.6 275 30 15 14.1 7.7
6250 5.3 41.5 265 26 13 11.5 6.3 | 6.9 44.4 275 29 15 11.8 6.5
6000 6.1 43.0 265 24 13 9.3 5.1 | 7.7 45.9 275 27 14 9.8 5.4
5750 6.8 44.2 265 23 12 12.1 6.6 | 8.4 47.1 275 26 14 8.6 4.7
5500 8.1 46.6 265 19 10 22.7 12.5 | 9.3 48.7 275 23 12 18.5 10.2
05/06/2024 at 1500 MDT | 05/06/2024 at 1800 MDT
|
CAPE... +38.7 LI... +0.5 | CAPE... +6.7 LI... +0.9
CINH... -14.4 K Index... +13.0 | CINH... -34.3 K Index... +14.8
|
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 -50.7 -59.3 240 31 16 2.4 1.3 | -50.5 -58.9 255 27 14 2.0 1.1
45000 -47.2 -53.0 255 31 16 2.2 1.2 | -47.5 -53.5 265 27 14 1.9 1.0
40000 -44.2 -47.6 250 37 19 2.0 1.1 | -44.8 -48.6 270 40 20 1.7 0.9
38000 -43.4 -46.1 250 40 20 -0.2 -0.1 | -44.5 -48.1 265 43 22 -1.2 -0.6
36000 -43.5 -46.3 255 43 22 -0.2 -0.1 | -45.2 -49.4 265 45 23 -1.2 -0.6
34000 -43.6 -46.5 260 47 24 -0.2 -0.1 | -45.9 -50.6 265 48 24 -1.1 -0.6
32000 -43.9 -47.0 265 48 25 -0.5 -0.3 | -46.2 -51.2 270 42 22 -0.6 -0.3
30000 -44.2 -47.6 270 50 25 -0.8 -0.4 | -46.6 -51.9 275 37 19 -0.7 -0.4
29000 -43.7 -46.7 270 49 25 2.7 1.5 | -45.5 -49.9 275 36 18 5.0 2.7
28000 -42.9 -45.2 275 48 25 2.7 1.5 | -44.0 -47.2 275 35 18 4.9 2.7
27000 -42.1 -43.8 275 46 24 2.6 1.5 | -42.5 -44.5 275 34 17 5.0 2.7
26000 -40.6 -41.1 275 45 23 6.2 3.4 | -40.8 -41.4 275 33 17 7.8 4.3
25000 -38.7 -37.7 275 43 22 6.3 3.5 | -38.0 -36.4 275 31 16 7.6 4.2
24000 -36.8 -34.2 270 41 21 6.3 3.5 | -35.7 -32.3 280 30 15 7.6 4.2
23000 -34.8 -30.6 270 38 19 7.8 4.3 | -33.3 -27.9 280 29 15 8.6 4.7
22000 -32.5 -26.5 275 34 17 7.7 4.2 | -30.7 -23.3 285 28 14 8.6 4.7
21000 -30.2 -22.4 280 30 15 7.7 4.2 | -28.1 -18.6 285 27 14 8.7 4.7
20000 -27.6 -17.7 285 29 15 8.9 4.9 | -25.6 -14.1 285 28 15 8.5 4.6
19500 -26.3 -15.3 285 29 15 8.9 4.9 | -24.3 -11.7 285 29 15 8.5 4.7
19000 -25.0 -13.0 285 29 15 8.9 4.9 | -23.0 -9.4 285 30 16 8.5 4.7
18500 -23.7 -10.7 290 29 15 8.9 4.9 | -21.8 -7.2 285 32 16 8.5 4.7
18000 -22.3 -8.1 290 30 16 8.8 4.8 | -20.5 -4.9 285 33 17 8.1 4.5
17500 -21.0 -5.8 290 32 17 8.8 4.8 | -19.3 -2.7 285 35 18 8.1 4.4
17000 -19.7 -3.5 290 34 18 8.7 4.8 | -18.1 -0.6 285 37 19 7.9 4.3
16500 -18.5 -1.3 290 36 18 8.2 4.5 | -17.0 1.4 285 39 20 7.6 4.2
16000 -17.3 0.9 290 37 19 8.3 4.5 | -15.9 3.4 285 40 21 7.6 4.2
15500 -16.0 3.2 290 38 20 8.1 4.5 | -14.7 5.5 285 42 21 7.8 4.3
15000 -14.8 5.4 290 40 21 8.2 4.5 | -13.6 7.5 285 42 22 7.8 4.3
14500 -13.6 7.5 285 41 21 8.1 4.4 | -12.5 9.5 280 43 22 7.6 4.1
14000 -12.4 9.7 285 42 22 8.1 4.4 | -11.4 11.5 280 42 22 7.5 4.1
13500 -11.2 11.8 285 43 22 8.0 4.4 | -10.2 13.6 280 42 22 8.0 4.4
13000 -10.1 13.8 285 42 22 8.0 4.4 | -9.0 15.8 275 42 21 8.2 4.5
12500 -8.9 16.0 280 42 22 8.2 4.5 | -7.8 18.0 275 41 21 8.4 4.6
12000 -7.0 19.4 275 40 20 8.4 4.6 | -6.5 20.3 275 40 21 8.6 4.7
11500 -5.7 21.7 275 38 20 9.6 5.3 | -5.3 22.5 270 39 20 8.8 4.8
11000 -4.2 24.4 275 38 19 9.8 5.4 | -3.3 26.1 270 37 19 9.2 5.0
10500 -3.0 26.6 275 37 19 7.2 4.0 | -2.1 28.2 270 35 18 6.6 3.6
10250 -2.4 27.7 275 37 19 8.3 4.5 | -1.5 29.3 270 35 18 8.5 4.6
10000 -1.7 28.9 275 36 19 11.9 6.5 | -0.7 30.7 270 34 17 13.0 7.1
9750 -0.7 30.7 270 36 18 10.9 6.0 | 0.2 32.4 270 33 17 10.8 5.9
9500 -0.1 31.8 270 35 18 8.6 4.7 | 0.8 33.4 270 32 17 7.8 4.3
9250 0.6 33.1 270 35 18 8.6 4.7 | 1.5 34.7 270 32 16 7.5 4.1
9000 1.3 34.3 270 35 18 11.0 6.0 | 2.1 35.8 270 31 16 11.7 6.4
8750 2.2 36.0 270 34 17 11.5 6.3 | 3.1 37.6 270 30 15 12.8 7.0
8500 2.9 37.2 270 33 17 9.2 5.0 | 3.8 38.8 270 29 15 8.9 4.9
8250 3.7 38.7 270 33 17 10.3 5.6 | 4.6 40.3 270 29 15 10.7 5.8
8000 4.4 39.9 270 32 16 8.3 4.6 | 5.3 41.5 270 28 14 7.4 4.0
7750 5.0 41.0 270 32 16 9.0 5.0 | 5.8 42.4 270 28 14 8.3 4.6
7500 5.8 42.4 270 31 16 11.0 6.0 | 6.6 43.9 270 27 14 12.0 6.6
7250 6.6 43.9 270 30 15 11.3 6.2 | 7.5 45.5 270 26 13 11.1 6.1
7000 7.3 45.1 270 29 15 7.5 4.1 | 8.2 46.8 270 25 13 7.0 3.8
6750 7.8 46.0 270 29 15 8.5 4.7 | 8.6 47.5 270 25 13 8.6 4.7
6500 8.7 47.7 270 28 14 13.3 7.3 | 9.6 49.3 270 24 12 13.8 7.6
6250 9.6 49.3 270 26 14 11.2 6.1 | 10.5 50.9 270 23 12 10.6 5.8
6000 10.4 50.7 270 25 13 9.1 5.0 | 11.1 52.0 270 22 11 6.8 3.7
5750 11.0 51.8 270 24 12 9.2 5.0 | 11.7 53.1 270 21 11 9.1 5.0
5500 12.0 53.6 270 21 11 18.4 10.1 | 12.6 54.7 270 17 9 16.9 9.3
________________________________________________________________________________
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.
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