Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
776
UXUS97 KBOU 020035
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1835 MDT Wednesday, May 1, 2024
This forecast is for Thursday, May 2, 2024:
If the trigger temperature of 50.8 F/10.4 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 675 ft/min (3.4 m/s)
Maximum height of thermals.................. 14075 ft MSL (8780 ft AGL)
Forecast maximum temperature................... 62.0 F/17.1 C
Time of trigger temperature.................... 0945 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................. 11697 ft MSL (6402 ft AGL)
Thermal soaring outlook for Friday 05/03....... Good
Wave Soaring Index............................. Good
Wave Soaring Index trend (to 1800 MDT)......... Little change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 34564 ft MSL (29269 ft AGL)
Wave soaring outlook for Friday 05/03.......... Fair
Remarks...
Sunrise/Sunset.................... 05:57:38 / 19:55:08 MDT
Total possible sunshine........... 13 hr 57 min 29 sec (837 min 29 sec)
Altitude of sun at 12:56:23 MDT... 65.92 degrees
Upper air data from numerical model forecast valid on 05/02/2024 at 0600 MDT
Freezing level.................. 8396 ft MSL (3101 ft AGL)
Convective condensation level... 16194 ft MSL (10899 ft AGL)
Lifted condensation level....... 15184 ft MSL (9889 ft AGL)
Lifted index.................... +3.2
K index......................... -17.7
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 -54.2 -65.6 240 47 24 0.9 0.5 M M M M M
45000 -52.9 -63.2 240 56 29 -0.3 -0.2 M M M M M
40000 -54.0 -65.2 240 71 37 -0.8 -0.4 M M M M M
38000 -53.8 -64.8 235 77 40 1.9 1.1 M M M M M
36000 -52.6 -62.7 235 81 42 1.9 1.0 M M M M M
34000 -51.4 -60.5 235 86 44 4.4 2.4 M M M M M
32000 -48.5 -55.3 235 81 42 4.8 2.7 M M M M M
30000 -44.9 -48.8 235 76 39 7.5 4.1 31.0 87.8 10.8 M M
29000 -42.7 -44.9 235 75 38 7.5 4.1 30.0 86.0 10.1 M M
28000 -40.4 -40.7 235 73 38 7.5 4.1 29.1 84.4 9.6 M M
27000 -38.2 -36.8 235 72 37 7.7 4.2 28.4 83.1 9.1 M M
26000 -35.8 -32.4 235 70 36 8.2 4.5 27.6 81.7 8.6 M M
25000 -33.3 -27.9 235 69 35 8.2 4.5 27.0 80.6 8.3 M M
24000 -30.9 -23.6 240 68 35 8.2 4.5 26.5 79.8 7.9 M M
23000 -28.5 -19.3 240 66 34 8.0 4.4 25.8 78.5 7.5 M M
22000 -26.1 -15.0 240 63 33 8.0 4.4 25.2 77.3 7.0 M M
21000 -23.7 -10.7 240 61 32 7.9 4.4 24.7 76.4 6.7 M M
20000 -21.3 -6.3 240 59 30 7.8 4.3 23.9 75.0 6.1 M M
19500 -20.1 -4.2 240 58 30 7.8 4.3 23.6 74.4 5.9 M M
19000 -19.0 -2.2 240 57 29 7.8 4.3 23.2 73.8 5.6 M M
18500 -17.8 -0.0 240 56 29 7.6 4.2 23.0 73.3 5.4 M M
18000 -16.8 1.8 240 54 28 6.5 3.6 22.4 72.4 5.0 M M
17500 -15.8 3.6 245 52 27 6.6 3.6 21.9 71.4 4.5 M M
17000 -14.8 5.4 245 50 26 5.7 3.1 21.3 70.3 4.0 M M
16500 -14.0 6.8 245 47 24 5.6 3.1 20.6 69.1 3.4 M M
16000 -13.2 8.2 250 45 23 5.4 2.9 19.9 67.8 2.8 M M
15500 -12.0 10.4 250 41 21 5.0 2.8 18.7 65.7 1.8 M M
15000 -11.3 11.7 255 38 20 5.3 2.9 17.9 64.3 1.1 M M
14500 -10.5 13.1 255 36 19 5.3 2.9 17.2 62.9 0.4 M M
14000 -9.7 14.5 255 34 17 5.3 2.9 16.5 61.7 -0.2 661 3.4
13500 -8.9 16.0 260 31 16 5.4 2.9 15.7 60.3 -0.9 623 3.2
13000 -8.1 17.4 260 29 15 5.6 3.1 15.0 59.0 -1.6 584 3.0
12500 -7.2 19.0 260 27 14 6.0 3.3 14.4 57.9 -2.2 543 2.8
12000 -6.3 20.7 260 25 13 6.2 3.4 13.8 56.9 -2.7 501 2.5
11500 -5.4 22.3 260 23 12 6.5 3.6 13.3 55.9 -3.3 458 2.3
11000 -4.4 24.1 260 22 11 6.4 3.5 12.8 55.0 -3.8 414 2.1
10500 -3.5 25.7 260 20 10 6.1 3.3 12.2 54.0 -4.4 372 1.9
10250 -3.0 26.6 260 19 10 6.9 3.8 11.9 53.5 -4.7 351 1.8
10000 -2.6 27.3 260 18 10 4.1 2.3 11.7 53.0 -4.9 330 1.7
9750 -2.4 27.7 260 18 9 4.3 2.4 11.1 52.0 -5.5 316 1.6
9500 -1.9 28.6 260 17 9 7.3 4.0 10.9 51.6 -5.8 295 1.5
9250 -1.4 29.5 260 17 9 6.4 3.5 10.6 51.2 -6.0 273 1.4
9000 -1.0 30.2 260 16 8 5.7 3.1 10.4 50.7 -6.3 253 1.3
8750 -0.6 30.9 265 15 8 5.6 3.1 10.0 50.1 -6.7 234 1.2
8500 -0.2 31.6 270 15 8 6.4 3.5 9.8 49.6 -7.0 213 1.1
8250 0.3 32.5 270 15 8 5.7 3.1 9.5 49.1 -7.3 193 1.0
8000 0.6 33.1 275 14 7 4.7 2.6 9.1 48.4 -7.7 175 0.9
7750 0.9 33.6 285 13 7 4.7 2.6 8.7 47.7 -8.1 158 0.8
7500 1.3 34.3 290 12 6 5.0 2.8 8.4 47.0 -8.6 140 0.7
7250 1.6 34.9 295 10 5 4.5 2.4 8.0 46.4 -9.0 122 0.6
7000 1.9 35.4 310 10 5 4.4 2.4 7.6 45.6 -9.4 106 0.5
6750 2.3 36.1 325 9 5 3.4 1.8 7.1 44.9 -9.9 89 0.5
6500 2.4 36.3 340 10 5 1.4 0.8 6.6 43.8 -10.4 77 0.4
6250 2.5 36.5 350 10 5 1.0 0.6 5.9 42.6 -11.2 68 0.3
6000 2.5 36.5 355 8 4 0.5 0.3 5.2 41.4 -11.9 60 0.3
5750 2.5 36.5 005 8 4 2.1 1.2 4.6 40.2 -12.7 53 0.3
5500 2.5 36.5 010 4 2 -0.6 -0.3 4.0 39.2 -13.4 44 0.2
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/02/2024 at 0900 MDT | 05/02/2024 at 1200 MDT
|
CAPE... +1.0 LI... +8.0 | CAPE... 0.0 LI... +5.7
CINH... 0.0 K Index... -14.4 | CINH... 0.0 K Index... +0.9
|
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 -52.8 -63.0 240 39 20 0.3 0.2 | -53.4 -64.1 240 36 19 0.7 0.4
45000 -52.3 -62.1 240 60 31 -0.8 -0.4 | -52.4 -62.3 240 58 30 -0.6 -0.4
40000 -54.6 -66.3 245 74 38 -1.5 -0.8 | -54.8 -66.6 245 67 34 -1.6 -0.9
38000 -54.7 -66.5 245 77 40 1.4 0.8 | -54.9 -66.8 250 70 36 1.7 0.9
36000 -53.9 -65.0 245 78 40 1.4 0.8 | -53.9 -65.0 250 72 37 1.7 0.9
34000 -52.9 -63.2 245 78 40 5.0 2.7 | -52.7 -62.9 250 74 38 5.8 3.2
32000 -49.2 -56.6 250 78 40 6.2 3.4 | -48.1 -54.6 250 74 38 6.8 3.8
30000 -44.8 -48.6 250 77 40 8.0 4.4 | -43.8 -46.8 250 74 38 8.0 4.4
29000 -42.5 -44.5 250 75 39 7.9 4.3 | -41.4 -42.5 250 73 38 8.0 4.4
28000 -40.1 -40.2 250 74 38 7.9 4.3 | -39.0 -38.2 250 73 37 8.0 4.4
27000 -37.7 -35.9 250 72 37 7.9 4.3 | -36.6 -33.9 250 72 37 7.7 4.2
26000 -35.4 -31.7 250 70 36 7.7 4.2 | -34.6 -30.3 255 71 37 6.7 3.7
25000 -33.1 -27.6 255 67 35 7.7 4.2 | -32.6 -26.7 255 69 36 6.8 3.7
24000 -30.8 -23.4 255 65 33 7.7 4.2 | -30.5 -22.9 255 68 35 6.7 3.7
23000 -28.5 -19.3 250 63 32 7.8 4.3 | -28.3 -18.9 255 66 34 7.8 4.3
22000 -26.1 -15.0 250 61 31 7.8 4.3 | -25.9 -14.6 250 65 33 7.8 4.3
21000 -23.8 -10.8 250 59 30 7.4 4.1 | -23.6 -10.5 250 64 33 7.7 4.2
20000 -21.7 -7.1 250 57 29 6.9 3.8 | -21.3 -6.3 250 61 31 7.5 4.1
19500 -20.7 -5.3 250 56 29 6.9 3.8 | -20.2 -4.4 250 59 30 7.5 4.1
19000 -19.7 -3.5 250 55 29 6.9 3.8 | -19.1 -2.4 250 57 30 7.5 4.1
18500 -18.6 -1.5 250 55 28 6.7 3.7 | -17.9 -0.2 250 56 29 7.3 4.0
18000 -17.7 0.1 255 53 27 5.8 3.2 | -17.0 1.4 255 54 28 6.1 3.3
17500 -16.8 1.8 255 52 27 5.9 3.3 | -16.0 3.2 255 53 27 6.3 3.4
17000 -16.0 3.2 255 50 26 5.6 3.1 | -15.2 4.6 255 52 27 4.3 2.4
16500 -15.2 4.6 255 49 25 5.5 3.0 | -14.3 6.3 260 50 26 4.0 2.2
16000 -13.9 7.0 255 46 24 5.6 3.1 | -13.8 7.2 260 49 25 3.1 1.7
15500 -13.1 8.4 255 43 22 5.6 3.0 | -13.4 7.9 260 46 24 3.1 1.7
15000 -12.3 9.9 260 41 21 5.8 3.2 | -12.8 9.0 260 44 22 4.9 2.7
14500 -11.4 11.5 260 39 20 5.8 3.2 | -12.0 10.4 260 39 20 5.6 3.1
14000 -10.5 13.1 260 36 19 6.0 3.3 | -11.2 11.8 255 35 18 6.9 3.8
13500 -9.6 14.7 260 33 17 6.1 3.3 | -10.0 14.0 255 30 16 8.1 4.4
13000 -8.7 16.3 260 31 16 6.4 3.5 | -8.8 16.2 250 26 13 8.3 4.6
12500 -7.7 18.1 260 29 15 6.9 3.8 | -7.5 18.5 245 23 12 8.6 4.7
12000 -6.6 20.1 260 26 14 6.8 3.7 | -6.2 20.8 245 20 10 8.3 4.6
11500 -5.6 21.9 260 24 13 6.7 3.7 | -5.1 22.8 245 18 9 7.7 4.2
11000 -4.6 23.7 260 22 11 6.8 3.8 | -3.9 25.0 240 16 8 7.1 3.9
10500 -3.6 25.5 255 20 10 7.0 3.8 | -3.0 26.6 240 15 8 5.8 3.2
10250 -3.1 26.4 255 19 10 7.4 4.0 | -2.5 27.5 235 14 7 6.3 3.5
10000 -2.6 27.3 255 18 9 3.6 2.0 | -2.0 28.4 235 13 7 9.4 5.1
9750 -2.5 27.5 255 17 9 3.8 2.1 | -1.3 29.7 230 12 6 7.9 4.4
9500 -2.0 28.4 250 15 8 7.1 3.9 | -0.9 30.4 230 11 6 5.1 2.8
9250 -1.5 29.3 250 14 7 6.2 3.4 | -0.4 31.3 225 10 5 5.8 3.2
9000 -1.1 30.0 245 12 6 5.7 3.1 | -0.1 31.8 220 9 4 4.4 2.4
8750 -0.8 30.6 245 11 6 4.6 2.5 | 0.2 32.4 205 7 3 3.7 2.0
8500 -0.5 31.1 240 10 5 4.7 2.6 | 0.4 32.7 185 5 3 3.6 2.0
8250 -0.2 31.6 240 9 5 4.1 2.2 | 0.7 33.3 155 5 3 5.2 2.8
8000 0.0 32.0 235 8 4 3.2 1.8 | 1.2 34.2 140 5 3 8.4 4.6
7750 0.2 32.4 230 7 3 2.3 1.3 | 1.8 35.2 135 6 3 9.4 5.2
7500 0.3 32.5 225 6 3 1.6 0.9 | 2.5 36.5 135 6 3 9.4 5.1
7250 0.4 32.7 220 4 2 1.9 1.0 | 3.2 37.8 130 6 3 9.9 5.4
7000 0.6 33.1 200 3 2 2.0 1.1 | 4.0 39.2 130 5 3 10.7 5.9
6750 0.8 33.4 165 2 1 1.6 0.9 | 4.7 40.5 130 5 3 9.3 5.1
6500 0.9 33.6 120 3 2 3.6 2.0 | 5.4 41.7 130 5 3 9.5 5.2
6250 1.3 34.3 115 4 2 6.4 3.5 | 6.2 43.2 130 5 3 11.7 6.4
6000 1.7 35.1 115 4 2 6.0 3.3 | 7.1 44.8 130 5 3 12.0 6.6
5750 2.1 35.8 115 4 2 7.7 4.2 | 8.0 46.4 130 5 3 12.0 6.6
5500 2.8 37.0 120 3 2 15.2 8.4 | 9.1 48.4 130 5 2 19.2 10.5
05/02/2024 at 1500 MDT | 05/02/2024 at 1800 MDT
|
CAPE... +23.3 LI... +0.5 | CAPE... +77.2 LI... -1.8
CINH... -41.7 K Index... +15.7 | CINH... -49.1 K Index... +19.2
|
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 -53.9 -65.0 235 42 22 0.7 0.4 | -53.6 -64.5 245 37 19 0.9 0.5
45000 -52.8 -63.0 240 58 30 -1.0 -0.6 | -52.3 -62.1 250 56 29 -1.9 -1.0
40000 -55.5 -67.9 250 62 32 -1.8 -1.0 | -57.4 -71.3 255 65 33 -3.4 -1.9
38000 -55.4 -67.7 255 65 33 2.7 1.5 | -57.4 -71.3 260 68 35 4.3 2.3
36000 -53.7 -64.7 260 70 36 2.7 1.5 | -54.8 -66.6 260 73 38 4.2 2.3
34000 -51.9 -61.4 265 75 39 6.8 3.7 | -52.1 -61.8 265 78 40 7.0 3.8
32000 -47.1 -52.8 260 75 39 7.1 3.9 | -47.4 -53.3 265 78 40 7.0 3.8
30000 -42.9 -45.2 255 76 39 7.3 4.0 | -43.2 -45.8 265 77 40 7.0 3.9
29000 -40.7 -41.3 255 75 39 7.3 4.0 | -41.1 -42.0 260 74 38 7.0 3.9
28000 -38.5 -37.3 255 75 39 7.3 4.0 | -39.0 -38.2 260 72 37 7.1 3.9
27000 -36.3 -33.3 255 75 38 7.1 3.9 | -36.9 -34.4 260 70 36 7.1 3.9
26000 -34.3 -29.7 255 74 38 6.4 3.5 | -34.7 -30.5 260 68 35 7.3 4.0
25000 -32.4 -26.3 255 73 37 6.4 3.5 | -32.5 -26.5 260 67 35 7.3 4.0
24000 -30.5 -22.9 255 72 37 6.4 3.5 | -30.3 -22.5 260 66 34 7.2 4.0
23000 -28.5 -19.3 255 70 36 6.9 3.8 | -28.4 -19.1 255 63 33 6.3 3.4
22000 -26.4 -15.5 255 69 35 6.9 3.8 | -26.5 -15.7 255 60 31 6.3 3.5
21000 -24.4 -11.9 255 67 35 6.7 3.7 | -24.7 -12.5 255 58 30 6.0 3.3
20000 -22.4 -8.3 255 64 33 6.5 3.5 | -23.0 -9.4 255 52 27 5.6 3.1
19500 -21.5 -6.7 255 62 32 6.5 3.5 | -22.2 -8.0 255 49 25 5.7 3.1
19000 -20.5 -4.9 255 60 31 6.5 3.5 | -21.3 -6.3 250 46 24 5.8 3.2
18500 -19.5 -3.1 255 58 30 6.3 3.4 | -20.5 -4.9 250 43 22 7.0 3.8
18000 -18.7 -1.7 255 55 28 5.4 2.9 | -19.2 -2.6 245 40 21 9.4 5.2
17500 -17.9 -0.2 255 50 26 5.3 2.9 | -17.8 -0.0 245 37 19 9.5 5.2
17000 -17.0 1.4 250 46 24 7.0 3.9 | -16.4 2.5 240 35 18 9.0 4.9
16500 -15.4 4.3 250 41 21 7.0 3.8 | -15.1 4.8 240 33 17 9.0 4.9
16000 -14.3 6.3 245 37 19 9.0 4.9 | -13.0 8.6 240 29 15 9.5 5.2
15500 -13.0 8.6 245 35 18 8.8 4.8 | -11.6 11.1 240 27 14 9.5 5.2
15000 -11.6 11.1 245 32 16 8.8 4.8 | -10.3 13.5 235 25 13 8.2 4.5
14500 -10.3 13.5 245 30 15 8.8 4.8 | -9.1 15.6 235 23 12 8.2 4.5
14000 -9.0 15.8 245 27 14 8.5 4.7 | -7.8 18.0 235 21 11 8.3 4.6
13500 -7.8 18.0 245 25 13 8.3 4.5 | -6.6 20.1 235 19 10 8.4 4.6
13000 -6.6 20.1 245 22 11 8.0 4.4 | -5.3 22.5 230 17 9 8.0 4.4
12500 -5.4 22.3 240 19 10 7.7 4.2 | -4.2 24.4 225 14 7 7.7 4.3
12000 -4.3 24.3 235 17 9 7.5 4.1 | -3.0 26.6 220 12 6 7.5 4.1
11500 -3.2 26.2 225 13 7 7.1 3.9 | -2.0 28.4 215 9 5 7.3 4.0
11000 -2.2 28.0 210 10 5 6.4 3.5 | -0.9 30.4 200 6 3 6.4 3.5
10500 -1.5 29.3 195 7 3 4.6 2.5 | -0.2 31.6 175 3 2 4.9 2.7
10250 -1.1 30.0 180 5 3 7.8 4.3 | 0.2 32.4 140 3 1 7.5 4.1
10000 -0.4 31.3 150 4 2 10.0 5.5 | 0.9 33.6 090 3 2 9.6 5.3
9750 0.2 32.4 140 4 2 7.9 4.3 | 1.5 34.7 080 4 2 8.6 4.7
9500 0.8 33.4 130 4 2 7.9 4.3 | 2.2 36.0 070 4 2 8.9 4.9
9250 1.4 34.5 120 4 2 7.9 4.3 | 2.8 37.0 065 5 3 8.7 4.8
9000 2.0 35.6 110 4 2 8.8 4.8 | 3.5 38.3 060 6 3 8.9 4.9
8750 2.7 36.9 110 4 2 9.7 5.3 | 4.1 39.4 060 6 3 9.2 5.1
8500 3.4 38.1 105 4 2 9.3 5.1 | 4.8 40.6 055 6 3 9.0 5.0
8250 4.1 39.4 100 4 2 9.9 5.4 | 5.5 41.9 055 6 3 9.7 5.3
8000 4.9 40.8 100 4 2 10.7 5.9 | 6.3 43.3 055 6 3 10.4 5.7
7750 5.6 42.1 095 4 2 10.1 5.6 | 7.0 44.6 050 6 3 9.7 5.3
7500 6.4 43.5 095 4 2 9.4 5.2 | 7.7 45.9 050 6 3 9.1 5.0
7250 7.1 44.8 090 4 2 10.2 5.6 | 8.4 47.1 050 6 3 9.8 5.4
7000 7.9 46.2 090 4 2 10.9 6.0 | 9.2 48.6 045 6 3 10.4 5.7
6750 8.6 47.5 090 4 2 9.2 5.0 | 9.9 49.8 045 6 3 9.7 5.3
6500 9.3 48.7 085 4 2 8.9 4.9 | 10.6 51.1 045 6 3 9.7 5.3
6250 10.1 50.2 080 3 2 11.4 6.2 | 11.4 52.5 045 6 3 10.6 5.8
6000 11.0 51.8 080 3 2 12.8 7.0 | 12.2 54.0 040 6 3 11.2 6.2
5750 11.9 53.4 075 3 2 10.0 5.5 | 13.0 55.4 040 6 3 9.3 5.1
5500 12.6 54.7 075 3 2 13.3 7.3 | 13.6 56.5 040 6 3 9.3 5.1
________________________________________________________________________________
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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