Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
059
UXUS97 KBOU 191329
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0728 MDT Sunday, May 19, 2024
This forecast is for Sunday, May 19, 2024:
If the trigger temperature of 72.5 F/22.5 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1424 ft/min (7.2 m/s)
Maximum height of thermals.................. 20240 ft MSL (14963 ft AGL)
Forecast maximum temperature................... 83.0 F/28.8 C
Time of trigger temperature.................... 1000 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................. 13850 ft MSL (8573 ft AGL)
Thermal soaring outlook for Monday 05/20....... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Little change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak NVA
Potential height of wave....................... 14397 ft MSL (9120 ft AGL)
Wave soaring outlook for Monday 05/20.......... Fair
Remarks... Moderate west to southwest flow aloft. Isolated high based showers
with gusty outflow winds this afternoon. Cool front arrives late
tonight.
Sunrise/Sunset.................... 05:40:39 / 20:11:23 MDT
Total possible sunshine........... 14 hr 30 min 44 sec (870 min 44 sec)
Altitude of sun at 12:56:01 MDT... 70.21 degrees
Upper air data from numerical model forecast valid on 05/19/2024 at 0600 MDT
Freezing level.................. 13617 ft MSL (8340 ft AGL)
Convective condensation level... 14555 ft MSL (9278 ft AGL)
Lifted condensation level....... 15880 ft MSL (10603 ft AGL)
Lifted index.................... -5.9
K index......................... +23.7
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 -55.0 -67.0 255 46 24 1.4 0.8 M M M M M
45000 -53.4 -64.1 255 47 24 -1.1 -0.6 M M M M M
40000 -55.1 -67.2 245 46 23 -1.0 -0.5 M M M M M
38000 -54.0 -65.2 240 43 22 2.8 1.5 M M M M M
36000 -52.4 -62.3 230 40 21 2.8 1.5 M M M M M
34000 -49.9 -57.8 225 37 19 6.7 3.7 M M M M M
32000 -45.4 -49.7 220 31 16 6.7 3.6 M M M M M
30000 -40.8 -41.4 220 29 15 8.7 4.8 34.1 93.4 4.3 M M
29000 -38.2 -36.8 225 30 15 8.7 4.8 33.7 92.6 4.0 M M
28000 -35.6 -32.1 225 30 15 8.7 4.8 33.3 92.0 3.8 M M
27000 -33.0 -27.4 230 31 16 8.1 4.5 32.9 91.1 3.5 M M
26000 -30.6 -23.1 230 32 16 8.2 4.5 32.2 89.9 3.0 M M
25000 -28.2 -18.8 235 33 17 8.2 4.5 31.6 88.9 2.6 M M
24000 -25.7 -14.3 240 33 17 8.1 4.4 31.1 87.9 2.1 M M
23000 -23.3 -9.9 240 30 16 8.1 4.4 30.4 86.7 1.6 M M
22000 -20.9 -5.6 240 28 14 8.1 4.4 29.8 85.7 1.1 M M
21000 -18.5 -1.3 245 27 14 7.6 4.2 29.2 84.5 0.6 M M
20000 -16.3 2.7 245 29 15 7.7 4.2 28.4 83.1 -0.1 1407 7.1
19500 -15.2 4.6 250 30 16 7.7 4.2 28.0 82.5 -0.4 1358 6.9
19000 -14.0 6.8 250 31 16 7.7 4.2 27.7 81.9 -0.7 1309 6.7
18500 -12.9 8.8 250 31 16 7.5 4.1 27.4 81.2 -1.1 1261 6.4
18000 -11.8 10.8 250 29 15 7.6 4.2 27.0 80.6 -1.5 1213 6.2
17500 -10.7 12.7 250 27 14 8.0 4.4 26.6 79.9 -1.8 1165 5.9
17000 -9.5 14.9 250 25 13 8.2 4.5 26.4 79.4 -2.1 1114 5.7
16500 -8.3 17.1 250 23 12 8.4 4.6 26.1 79.0 -2.4 1064 5.4
16000 -7.0 19.4 250 23 12 9.4 5.1 26.0 78.8 -2.5 1009 5.1
15500 -4.9 23.2 255 23 12 9.3 5.1 25.9 78.6 -2.7 925 4.7
15000 -3.5 25.7 260 24 12 9.3 5.1 25.8 78.4 -2.8 868 4.4
14500 -2.1 28.2 260 26 13 9.3 5.1 25.7 78.3 -2.9 812 4.1
14000 -0.8 30.6 260 25 13 9.1 5.0 25.6 78.1 -3.0 757 3.8
13500 0.6 33.1 260 24 12 9.2 5.0 25.5 77.9 -3.1 702 3.6
13000 1.9 35.4 260 23 12 9.1 5.0 25.4 77.7 -3.3 647 3.3
12500 3.3 37.9 265 22 11 9.2 5.0 25.3 77.6 -3.4 591 3.0
12000 4.6 40.3 265 21 11 8.1 4.4 25.1 77.3 -3.5 537 2.7
11500 5.7 42.3 265 17 9 8.1 4.5 24.9 76.8 -3.9 488 2.5
11000 6.8 44.2 265 15 8 7.1 3.9 24.5 76.2 -4.3 440 2.2
10500 7.9 46.2 265 13 7 6.4 3.5 24.1 75.4 -4.7 393 2.0
10250 8.4 47.1 270 12 6 9.6 5.3 23.9 75.0 -4.9 370 1.9
10000 9.2 48.6 270 10 5 9.5 5.2 24.0 75.2 -4.9 339 1.7
9750 9.7 49.5 275 9 5 5.9 3.3 23.8 74.8 -5.1 317 1.6
9500 10.2 50.4 275 9 4 7.4 4.1 23.5 74.4 -5.4 295 1.5
9250 10.7 51.3 280 8 4 5.2 2.8 23.3 74.0 -5.6 273 1.4
9000 11.0 51.8 280 7 4 5.4 3.0 22.9 73.2 -6.1 256 1.3
8750 11.5 52.7 270 7 4 7.5 4.1 22.7 72.8 -6.3 234 1.2
8500 12.0 53.6 265 7 3 7.3 4.0 22.5 72.5 -6.5 211 1.1
8250 12.5 54.5 260 7 3 6.1 3.3 22.3 72.1 -6.8 188 1.0
8000 12.9 55.2 250 7 4 4.5 2.5 21.9 71.4 -7.2 170 0.9
7750 13.2 55.8 245 7 4 4.6 2.5 21.5 70.7 -7.6 153 0.8
7500 13.5 56.3 235 8 4 4.3 2.3 21.1 70.0 -8.0 136 0.7
7250 13.8 56.8 230 9 4 3.6 2.0 20.7 69.2 -8.5 121 0.6
7000 14.0 57.2 225 9 5 2.9 1.6 20.2 68.3 -9.0 107 0.5
6750 14.2 57.6 220 10 5 3.2 1.7 19.6 67.4 -9.6 94 0.5
6500 14.3 57.7 215 12 6 -0.5 -0.3 19.1 66.3 -10.2 82 0.4
6250 14.0 57.2 210 12 6 -5.0 -2.8 18.1 64.5 -11.3 83 0.4
6000 13.6 56.5 205 13 7 -4.3 -2.4 16.9 62.5 -12.4 88 0.4
5750 13.2 55.8 200 14 7 -8.1 -4.4 15.8 60.5 -13.6 94 0.5
5500 12.2 54.0 190 11 6 -14.9 -8.2 14.2 57.5 -15.4 116 0.6
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/19/2024 at 0900 MDT | 05/19/2024 at 1200 MDT
|
CAPE... +283.5 LI... -0.6 | CAPE... +307.4 LI... -1.2
CINH... -177.3 K Index... +18.1 | CINH... -5.1 K Index... +27.6
|
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 -55.0 -67.0 255 47 24 1.5 0.8 | -54.6 -66.3 255 47 24 1.5 0.8
45000 -53.1 -63.6 255 47 24 -0.2 -0.1 | -52.7 -62.9 260 47 24 -0.1 -0.1
40000 -53.4 -64.1 255 38 19 -0.1 -0.1 | -53.0 -63.4 260 46 24 -0.3 -0.2
38000 -52.5 -62.5 255 33 17 2.1 1.1 | -52.0 -61.6 260 41 21 2.0 1.1
36000 -51.3 -60.3 250 29 15 2.1 1.1 | -50.8 -59.4 265 34 18 2.0 1.1
34000 -48.8 -55.8 245 26 13 5.9 3.3 | -48.5 -55.3 265 30 15 6.6 3.6
32000 -45.3 -49.5 235 27 14 5.9 3.3 | -44.5 -48.1 270 27 14 6.6 3.6
30000 -41.0 -41.8 235 28 14 8.4 4.6 | -40.3 -40.5 265 25 13 7.8 4.3
29000 -38.5 -37.3 235 27 14 8.4 4.6 | -38.0 -36.4 265 24 13 7.8 4.3
28000 -36.0 -32.8 235 27 14 8.4 4.6 | -35.6 -32.1 260 24 12 7.8 4.3
27000 -33.6 -28.5 235 27 14 7.3 4.0 | -32.7 -26.9 260 23 12 7.6 4.2
26000 -31.4 -24.5 240 26 13 7.4 4.0 | -30.5 -22.9 255 22 11 7.6 4.2
25000 -29.2 -20.6 240 25 13 7.4 4.1 | -28.2 -18.8 255 21 11 7.6 4.2
24000 -26.9 -16.4 240 24 12 9.0 5.0 | -25.9 -14.6 250 20 10 8.0 4.4
23000 -24.2 -11.6 240 24 12 8.8 4.9 | -23.5 -10.3 250 19 10 8.0 4.4
22000 -21.6 -6.9 240 25 13 8.8 4.8 | -21.2 -6.2 250 19 10 8.0 4.4
21000 -19.1 -2.4 240 25 13 7.5 4.1 | -18.8 -1.8 250 19 10 8.3 4.6
20000 -16.9 1.6 240 26 14 7.6 4.2 | -16.3 2.7 255 21 11 8.4 4.6
19500 -15.7 3.7 240 27 14 7.6 4.2 | -15.0 5.0 255 21 11 8.4 4.6
19000 -14.6 5.7 245 28 14 7.7 4.2 | -13.8 7.2 260 22 12 8.4 4.6
18500 -13.5 7.7 240 27 14 7.1 3.9 | -12.6 9.3 260 24 12 7.4 4.1
18000 -12.5 9.5 240 25 13 7.2 4.0 | -11.5 11.3 260 26 13 7.5 4.1
17500 -10.7 12.7 235 22 11 9.4 5.2 | -10.5 13.1 260 28 14 7.3 4.0
17000 -9.4 15.1 235 21 11 9.2 5.0 | -9.4 15.1 260 28 15 7.2 4.0
16500 -8.0 17.6 230 20 10 9.6 5.3 | -8.4 16.9 260 29 15 7.4 4.0
16000 -6.5 20.3 235 22 11 9.8 5.4 | -7.3 18.9 260 29 15 8.1 4.4
15500 -5.1 22.8 240 24 12 9.6 5.2 | -6.2 20.8 260 28 14 8.0 4.4
15000 -3.7 25.3 245 26 13 8.9 4.9 | -5.0 23.0 260 26 13 9.0 4.9
14500 -2.4 27.7 250 28 15 8.9 4.9 | -3.6 25.5 260 24 13 9.0 4.9
14000 -1.0 30.2 250 30 15 8.9 4.9 | -1.6 29.1 260 22 11 9.4 5.1
13500 0.3 32.5 255 30 15 9.0 4.9 | -0.2 31.6 255 21 11 9.4 5.1
13000 1.6 34.9 260 29 15 8.7 4.8 | 1.2 34.2 255 20 10 9.2 5.1
12500 2.9 37.2 260 29 15 8.6 4.7 | 2.5 36.5 255 19 10 9.2 5.1
12000 4.2 39.6 265 28 14 9.4 5.1 | 3.9 39.0 255 17 9 9.4 5.1
11500 5.6 42.1 265 25 13 9.5 5.2 | 5.3 41.5 250 16 8 9.5 5.2
11000 6.9 44.4 270 23 12 7.8 4.3 | 6.6 43.9 250 14 7 7.5 4.1
10500 8.0 46.4 270 22 11 6.7 3.7 | 7.7 45.9 245 12 6 6.8 3.7
10250 8.6 47.5 270 21 11 10.8 5.9 | 8.3 46.9 245 12 6 11.0 6.1
10000 9.6 49.3 270 20 10 11.6 6.4 | 9.2 48.6 245 10 5 12.1 6.6
9750 10.2 50.4 270 19 10 8.0 4.4 | 9.9 49.8 240 9 5 9.1 5.0
9500 10.8 51.4 270 18 9 9.2 5.0 | 10.7 51.3 240 8 4 9.9 5.4
9250 11.5 52.7 270 17 9 8.2 4.5 | 11.4 52.5 235 7 4 9.5 5.2
9000 12.0 53.6 270 16 8 7.3 4.0 | 12.1 53.8 235 7 4 9.7 5.3
8750 12.6 54.7 270 15 8 7.3 4.0 | 12.8 55.0 235 7 4 10.1 5.5
8500 13.1 55.6 270 14 7 7.3 4.0 | 13.6 56.5 235 7 3 10.0 5.5
8250 13.6 56.5 275 13 7 7.3 4.0 | 14.3 57.7 235 6 3 10.1 5.6
8000 14.2 57.6 270 12 6 6.9 3.8 | 15.0 59.0 235 6 3 9.9 5.4
7750 14.6 58.3 270 11 5 6.5 3.6 | 15.8 60.4 235 6 3 9.6 5.3
7500 15.1 59.2 270 10 5 6.4 3.5 | 16.5 61.7 235 6 3 9.6 5.3
7250 15.5 59.9 265 9 5 5.1 2.8 | 17.2 63.0 235 6 3 9.9 5.4
7000 15.8 60.4 265 8 4 4.0 2.2 | 18.0 64.4 235 6 3 10.1 5.5
6750 16.0 60.8 265 8 4 2.5 1.3 | 18.7 65.7 235 6 3 9.8 5.4
6500 16.2 61.2 260 7 4 1.6 0.9 | 19.4 66.9 235 6 3 10.2 5.6
6250 16.3 61.3 255 7 3 2.6 1.4 | 20.2 68.4 235 5 3 11.4 6.2
6000 16.4 61.5 240 6 3 2.5 1.4 | 21.1 70.0 235 5 3 12.3 6.8
5750 16.5 61.7 225 6 3 3.7 2.0 | 22.0 71.6 235 5 3 9.3 5.1
5500 16.9 62.4 215 6 3 12.3 6.8 | 22.7 72.9 235 5 3 13.1 7.2
05/19/2024 at 1500 MDT | 05/19/2024 at 1800 MDT
|
CAPE... +201.1 LI... -1.3 | CAPE... +461.1 LI... -2.2
CINH... -5.1 K Index... +25.2 | CINH... -25.3 K Index... +25.3
|
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 -54.9 -66.8 255 51 26 1.0 0.6 | -55.4 -67.7 260 48 25 1.5 0.8
45000 -53.7 -64.7 260 52 27 -1.0 -0.6 | -53.6 -64.5 260 51 26 -0.6 -0.3
40000 -55.3 -67.5 265 57 29 -0.9 -0.5 | -54.5 -66.1 265 60 31 -0.5 -0.3
38000 -53.9 -65.0 270 54 28 3.4 1.8 | -53.1 -63.6 270 58 30 2.7 1.5
36000 -51.6 -60.9 275 48 25 3.4 1.8 | -51.5 -60.7 265 55 28 2.7 1.5
34000 -48.4 -55.1 275 44 23 7.3 4.0 | -48.4 -55.1 265 52 27 7.7 4.2
32000 -44.0 -47.2 280 42 21 7.3 4.0 | -43.7 -46.7 270 49 25 7.7 4.2
30000 -39.3 -38.7 280 38 20 8.3 4.5 | -38.8 -37.8 270 45 23 8.6 4.7
29000 -36.9 -34.4 275 36 18 8.3 4.5 | -36.2 -33.2 265 44 22 8.6 4.7
28000 -34.4 -29.9 275 33 17 8.3 4.5 | -33.7 -28.7 265 42 22 8.6 4.7
27000 -32.0 -25.6 275 31 16 7.9 4.3 | -31.2 -24.2 265 40 20 7.6 4.2
26000 -29.6 -21.3 275 29 15 7.9 4.3 | -28.9 -20.0 260 37 19 7.7 4.2
25000 -27.2 -17.0 275 26 14 7.9 4.4 | -26.6 -15.9 260 35 18 7.7 4.2
24000 -24.8 -12.6 275 24 13 8.0 4.4 | -24.4 -11.9 255 32 17 6.4 3.5
23000 -22.4 -8.3 275 23 12 8.0 4.4 | -22.5 -8.5 255 32 16 6.6 3.6
22000 -20.0 -4.0 275 22 11 8.0 4.4 | -20.6 -5.1 255 31 16 6.7 3.7
21000 -17.8 -0.0 270 21 11 6.7 3.7 | -18.4 -1.1 250 30 15 8.5 4.7
20000 -15.8 3.6 265 23 12 6.8 3.7 | -16.0 3.2 250 28 14 8.5 4.6
19500 -14.8 5.4 265 24 12 6.8 3.7 | -14.1 6.6 250 26 14 8.5 4.7
19000 -13.8 7.2 265 25 13 6.7 3.7 | -12.9 8.8 245 25 13 8.6 4.7
18500 -12.7 9.1 260 26 13 8.7 4.8 | -11.6 11.1 245 24 12 8.8 4.8
18000 -10.9 12.4 260 28 14 8.7 4.8 | -10.3 13.5 245 22 11 8.9 4.9
17500 -9.6 14.7 260 27 14 8.4 4.6 | -9.1 15.6 245 21 11 7.5 4.1
17000 -8.4 16.9 255 26 13 8.4 4.6 | -8.0 17.6 245 19 10 7.6 4.2
16500 -7.2 19.0 255 24 12 8.7 4.8 | -6.9 19.6 245 18 9 8.4 4.6
16000 -5.9 21.4 255 22 11 8.8 4.8 | -5.5 22.1 240 17 9 8.9 4.9
15500 -4.6 23.7 255 21 11 8.9 4.9 | -4.2 24.4 240 15 8 8.9 4.9
15000 -3.2 26.2 255 19 10 9.3 5.1 | -2.8 27.0 240 14 7 9.1 5.0
14500 -1.8 28.8 250 17 9 9.3 5.1 | -1.5 29.3 235 13 7 9.1 5.0
14000 -0.5 31.1 250 15 8 8.9 4.9 | -0.1 31.8 235 12 6 9.0 4.9
13500 0.9 33.6 250 13 7 8.9 4.9 | 1.2 34.2 230 11 5 9.0 4.9
13000 2.2 36.0 250 11 6 8.9 4.9 | 2.6 36.7 225 9 5 8.9 4.9
12500 3.5 38.3 245 9 5 8.9 4.9 | 3.9 39.0 225 8 4 8.9 4.9
12000 4.8 40.6 245 8 4 9.6 5.3 | 5.2 41.4 225 6 3 8.9 4.9
11500 6.3 43.3 245 7 4 9.8 5.4 | 6.5 43.7 230 5 3 8.9 4.9
11000 7.7 45.9 250 7 4 9.0 5.0 | 7.9 46.2 235 4 2 8.8 4.8
10500 9.0 48.2 250 7 4 8.6 4.7 | 9.2 48.6 255 3 2 8.6 4.7
10250 9.8 49.6 250 7 4 11.7 6.4 | 9.9 49.8 265 3 1 10.1 5.5
10000 10.7 51.3 250 7 4 11.7 6.4 | 10.6 51.1 280 3 1 10.0 5.5
9750 11.4 52.5 250 7 4 9.2 5.0 | 11.3 52.3 300 3 2 8.7 4.8
9500 12.2 54.0 250 7 4 9.6 5.3 | 12.0 53.6 315 3 2 8.7 4.8
9250 12.9 55.2 250 7 4 10.5 5.8 | 12.6 54.7 325 4 2 9.9 5.5
9000 13.7 56.7 250 7 3 10.6 5.8 | 13.4 56.1 330 5 3 9.4 5.1
8750 14.5 58.1 250 7 3 9.6 5.2 | 13.9 57.0 335 6 3 7.7 4.2
8500 15.2 59.4 250 7 3 9.6 5.2 | 14.5 58.1 340 8 4 7.7 4.2
8250 15.9 60.6 250 7 3 10.6 5.8 | 15.1 59.2 340 9 5 9.3 5.1
8000 16.7 62.1 250 6 3 10.5 5.8 | 15.8 60.4 345 11 6 10.0 5.5
7750 17.4 63.3 250 6 3 9.1 5.0 | 16.5 61.7 345 12 6 8.3 4.6
7500 18.1 64.6 250 6 3 8.9 4.9 | 17.1 62.8 350 14 7 7.9 4.3
7250 18.8 65.8 250 6 3 10.2 5.6 | 17.7 63.9 350 15 8 9.3 5.1
7000 19.7 67.5 255 6 3 11.2 6.1 | 18.5 65.3 355 15 8 10.7 5.8
6750 20.4 68.7 255 6 3 9.9 5.4 | 19.2 66.6 355 15 8 9.7 5.3
6500 21.2 70.2 255 6 3 9.8 5.4 | 19.9 67.8 355 15 8 9.5 5.2
6250 21.9 71.4 255 6 3 11.0 6.0 | 20.6 69.1 355 15 8 10.5 5.8
6000 22.8 73.0 255 6 3 12.1 6.7 | 21.5 70.7 355 15 8 11.4 6.3
5750 23.7 74.7 255 6 3 10.2 5.6 | 22.3 72.1 355 15 8 9.6 5.3
5500 24.5 76.1 255 5 3 14.9 8.2 | 22.9 73.2 355 14 7 9.5 5.2
________________________________________________________________________________
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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