Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
934
UXUS97 KBOU 051305
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0704 MDT Sunday, May 5, 2024
This forecast is for Sunday, May 5, 2024:
If the trigger temperature of 69.1 F/20.6 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 1221 ft/min (6.2 m/s)
Maximum height of thermals.................. 20042 ft MSL (14710 ft AGL)
Forecast maximum temperature................... 78.0 F/26.0 C
Time of trigger temperature.................... 1145 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 14085 ft MSL (8753 ft AGL)
Thermal soaring outlook for Monday 05/06....... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Slight increase
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 15437 ft MSL (10105 ft AGL)
Wave soaring outlook for Monday 05/06.......... Good
Remarks... Warm, windy this afternoon.
Sunrise/Sunset.................... 05:54:08 / 19:58:06 MDT
Total possible sunshine........... 14 hr 3 min 58 sec (843 min 58 sec)
Altitude of sun at 12:56:07 MDT... 66.77 degrees
Upper air data from numerical model forecast valid on 05/05/2024 at 0600 MDT
Freezing level.................. 12563 ft MSL (7231 ft AGL)
Convective condensation level... 15420 ft MSL (10088 ft AGL)
Lifted condensation level....... 16550 ft MSL (11218 ft AGL)
Lifted index.................... -2.9
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 -57.2 -71.0 245 35 18 0.1 0.1 M M M M M
45000 -57.2 -71.0 245 38 20 -2.6 -1.4 M M M M M
40000 -61.4 -78.5 265 34 17 -2.9 -1.6 M M M M M
38000 -59.0 -74.2 270 33 17 8.3 4.5 M M M M M
36000 -53.4 -64.1 275 33 17 8.3 4.5 M M M M M
34000 -48.3 -54.9 275 30 16 8.5 4.7 M M M M M
32000 -43.2 -45.8 270 25 13 8.5 4.7 M M M M M
30000 -38.3 -36.9 265 21 11 7.6 4.2 37.9 100.2 9.3 M M
29000 -36.0 -32.8 255 22 11 7.6 4.2 37.0 98.6 8.7 M M
28000 -33.8 -28.8 250 23 12 7.6 4.2 36.2 97.2 8.2 M M
27000 -31.6 -24.9 245 24 13 5.2 2.8 35.3 95.5 7.6 M M
26000 -30.1 -22.2 235 25 13 5.0 2.7 33.4 92.0 6.2 M M
25000 -28.6 -19.5 230 25 13 5.0 2.7 31.6 88.9 4.8 M M
24000 -27.1 -16.8 225 26 13 5.7 3.1 30.0 85.9 3.6 M M
23000 -25.2 -13.4 225 24 12 6.4 3.5 28.6 83.5 2.5 M M
22000 -23.3 -9.9 220 22 11 6.5 3.5 27.4 81.4 1.5 M M
21000 -21.3 -6.3 215 20 10 7.8 4.3 26.4 79.5 0.7 M M
20000 -18.9 -2.0 220 18 9 8.0 4.4 25.7 78.3 0.0 M M
19500 -17.1 1.2 220 17 9 8.0 4.4 25.3 77.5 -0.4 1353 6.9
19000 -15.9 3.4 220 16 8 8.0 4.4 25.0 77.0 -0.6 1302 6.6
18500 -14.7 5.5 225 15 8 8.3 4.6 24.7 76.5 -0.8 1251 6.4
18000 -13.5 7.7 230 15 8 8.3 4.5 24.5 76.0 -1.1 1199 6.1
17500 -12.3 9.9 230 15 8 8.3 4.5 24.2 75.6 -1.3 1148 5.8
17000 -11.0 12.2 235 15 8 8.3 4.5 24.0 75.1 -1.6 1096 5.6
16500 -9.8 14.4 240 16 8 8.3 4.6 23.7 74.7 -1.8 1045 5.3
16000 -8.6 16.5 245 16 8 8.4 4.6 23.5 74.3 -2.1 993 5.0
15500 -7.3 18.9 250 17 9 8.4 4.6 23.3 73.9 -2.3 941 4.8
15000 -6.1 21.0 250 17 9 8.3 4.6 23.0 73.4 -2.6 889 4.5
14500 -4.9 23.2 250 17 9 8.3 4.6 22.8 73.0 -2.8 838 4.3
14000 -3.7 25.3 250 17 9 8.6 4.7 22.6 72.6 -3.1 786 4.0
13500 -2.4 27.7 250 17 9 8.6 4.7 22.4 72.3 -3.3 733 3.7
13000 -1.1 30.0 250 16 8 8.8 4.8 22.2 72.0 -3.5 680 3.5
12500 0.2 32.4 250 16 8 8.9 4.9 22.1 71.7 -3.6 625 3.2
12000 1.6 34.9 250 16 8 9.0 4.9 21.9 71.5 -3.8 571 2.9
11500 2.9 37.2 250 15 8 9.1 5.0 21.8 71.3 -3.9 515 2.6
11000 4.3 39.7 245 15 8 8.5 4.7 21.7 71.1 -4.0 460 2.3
10500 5.4 41.7 245 15 8 7.1 3.9 21.4 70.6 -4.4 410 2.1
10250 6.0 42.8 245 15 7 10.3 5.6 21.3 70.3 -4.5 386 2.0
10000 6.9 44.4 240 15 8 11.0 6.0 21.5 70.6 -4.4 352 1.8
9750 7.5 45.5 240 15 8 7.9 4.3 21.4 70.5 -4.5 325 1.7
9500 8.1 46.6 235 15 8 8.5 4.7 21.3 70.3 -4.6 300 1.5
9250 8.7 47.7 235 15 8 7.6 4.2 21.1 70.1 -4.8 274 1.4
9000 9.2 48.6 235 15 8 6.0 3.3 20.9 69.6 -5.0 252 1.3
8750 9.7 49.5 235 15 8 6.3 3.4 20.6 69.1 -5.3 232 1.2
8500 10.1 50.2 230 16 8 6.9 3.8 20.4 68.7 -5.6 210 1.1
8250 10.6 51.1 230 16 8 6.5 3.6 20.1 68.3 -5.9 188 1.0
8000 11.0 51.8 230 16 8 3.6 2.0 19.8 67.7 -6.2 170 0.9
7750 11.1 52.0 230 15 8 1.2 0.7 19.2 66.6 -6.9 159 0.8
7500 11.2 52.2 230 15 8 1.8 1.0 18.6 65.4 -7.5 149 0.8
7250 11.3 52.3 230 14 7 0.7 0.4 17.9 64.3 -8.2 139 0.7
7000 11.2 52.2 230 13 7 -0.8 -0.5 17.2 62.9 -9.0 133 0.7
6750 11.1 52.0 235 13 6 -2.8 -1.6 16.3 61.4 -9.9 130 0.7
6500 10.8 51.4 235 11 6 -4.0 -2.2 15.3 59.5 -11.0 132 0.7
6250 10.4 50.7 235 10 5 -5.0 -2.8 14.2 57.6 -12.0 134 0.7
6000 10.0 50.0 230 9 5 -6.2 -3.4 13.0 55.5 -13.3 141 0.7
5750 9.5 49.1 230 9 5 -5.8 -3.2 11.8 53.3 -14.5 147 0.7
5500 8.8 47.8 225 6 3 -14.6 -8.0 10.5 50.8 -16.0 160 0.8
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/05/2024 at 0900 MDT | 05/05/2024 at 1200 MDT
|
CAPE... +19.4 LI... +1.3 | CAPE... +48.8 LI... +0.3
CINH... -33.9 K Index... +6.6 | CINH... -21.5 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 -57.0 -70.6 235 32 16 -0.7 -0.4 | -57.3 -71.1 235 34 18 0.1 0.1
45000 -58.1 -72.6 240 34 18 -1.4 -0.8 | -57.3 -71.1 240 35 18 -2.2 -1.2
40000 -60.4 -76.7 250 42 21 -1.6 -0.9 | -60.5 -76.9 255 60 31 -2.2 -1.2
38000 -58.1 -72.6 250 42 22 6.9 3.8 | -58.0 -72.4 255 63 33 7.6 4.2
36000 -53.4 -64.1 245 41 21 6.9 3.8 | -52.8 -63.0 255 62 32 7.6 4.2
34000 -48.9 -56.0 245 41 21 8.6 4.7 | -48.2 -54.8 250 58 30 7.7 4.2
32000 -43.7 -46.7 240 41 21 8.6 4.7 | -43.6 -46.5 245 51 26 7.7 4.2
30000 -38.7 -37.7 240 41 21 8.0 4.4 | -38.9 -38.0 240 46 24 8.0 4.4
29000 -36.2 -33.2 240 41 21 8.1 4.4 | -36.5 -33.7 240 46 23 8.0 4.4
28000 -33.8 -28.8 240 41 21 8.1 4.4 | -34.1 -29.4 235 45 23 8.1 4.4
27000 -31.6 -24.9 240 41 21 5.8 3.2 | -31.7 -25.1 235 44 23 7.6 4.1
26000 -29.8 -21.6 235 38 20 5.8 3.2 | -29.4 -20.9 235 43 22 7.6 4.2
25000 -28.1 -18.6 235 36 19 5.8 3.2 | -27.2 -17.0 235 41 21 7.6 4.2
24000 -26.4 -15.5 230 34 17 6.4 3.5 | -24.9 -12.8 235 40 20 7.1 3.9
23000 -24.3 -11.7 230 31 16 6.8 3.7 | -22.9 -9.2 230 37 19 6.7 3.7
22000 -22.2 -8.0 225 29 15 6.8 3.8 | -20.9 -5.6 230 35 18 6.7 3.7
21000 -20.1 -4.2 225 27 14 7.5 4.1 | -18.9 -2.0 225 33 17 6.7 3.7
20000 -17.8 -0.0 225 25 13 7.6 4.2 | -16.9 1.6 220 31 16 6.7 3.7
19500 -16.1 3.0 220 23 12 7.6 4.2 | -15.9 3.4 220 30 16 6.7 3.7
19000 -15.0 5.0 220 22 11 7.6 4.2 | -14.9 5.2 215 30 15 6.7 3.7
18500 -13.8 7.2 225 21 11 8.0 4.4 | -13.2 8.2 210 29 15 8.5 4.7
18000 -12.7 9.1 225 21 11 7.9 4.4 | -12.0 10.4 210 28 14 8.4 4.6
17500 -11.5 11.3 225 20 10 8.1 4.4 | -10.7 12.7 210 27 14 8.1 4.5
17000 -10.3 13.5 225 20 10 8.1 4.5 | -9.5 14.9 210 27 14 8.0 4.4
16500 -9.1 15.6 225 20 10 8.1 4.5 | -8.3 17.1 210 27 14 8.0 4.4
16000 -7.9 17.8 225 20 10 8.0 4.4 | -7.1 19.2 210 27 14 7.6 4.2
15500 -6.7 19.9 225 20 10 8.1 4.4 | -6.0 21.2 215 27 14 7.7 4.2
15000 -5.5 22.1 230 20 10 7.9 4.3 | -4.9 23.2 215 27 14 6.7 3.7
14500 -4.3 24.3 230 20 10 7.9 4.3 | -3.9 25.0 210 27 14 6.7 3.7
14000 -3.2 26.2 230 19 10 7.7 4.2 | -3.0 26.6 210 27 14 6.9 3.8
13500 -2.0 28.4 230 19 10 7.7 4.2 | -1.9 28.6 215 27 14 7.0 3.9
13000 -0.9 30.4 225 19 10 7.9 4.3 | -0.9 30.4 215 27 14 7.6 4.1
12500 0.2 32.4 225 18 9 8.0 4.4 | 0.3 32.5 215 27 14 8.1 4.5
12000 1.4 34.5 225 18 9 8.2 4.5 | 1.5 34.7 215 27 14 8.2 4.5
11500 2.7 36.9 220 18 9 8.4 4.6 | 2.7 36.9 215 27 14 8.2 4.5
11000 3.9 39.0 215 17 9 8.0 4.4 | 3.9 39.0 215 27 14 7.9 4.3
10500 5.0 41.0 215 17 9 6.8 3.7 | 4.9 40.8 210 25 13 6.4 3.5
10250 5.6 42.1 215 17 9 9.7 5.3 | 5.5 41.9 210 25 13 9.8 5.4
10000 6.4 43.5 215 17 9 10.8 5.9 | 6.3 43.3 205 24 12 11.6 6.4
9750 7.1 44.8 210 17 9 8.0 4.4 | 7.1 44.8 205 23 12 8.8 4.9
9500 7.7 45.9 210 17 9 8.6 4.7 | 7.7 45.9 205 23 12 8.6 4.7
9250 8.3 46.9 210 17 9 7.3 4.0 | 8.4 47.1 205 22 11 9.4 5.2
9000 8.7 47.7 210 18 9 6.9 3.8 | 9.1 48.4 200 22 11 10.0 5.5
8750 9.3 48.7 210 18 9 7.8 4.3 | 9.8 49.6 200 21 11 9.0 4.9
8500 9.8 49.6 210 18 9 7.7 4.2 | 10.4 50.7 200 21 11 8.9 4.9
8250 10.4 50.7 210 19 10 7.4 4.0 | 11.1 52.0 200 20 11 8.7 4.8
8000 10.8 51.4 210 19 10 4.9 2.7 | 11.7 53.1 200 20 10 7.5 4.1
7750 11.1 52.0 210 19 10 3.8 2.1 | 12.2 54.0 200 19 10 7.7 4.2
7500 11.4 52.5 210 19 10 4.8 2.6 | 12.8 55.0 195 18 9 8.7 4.7
7250 11.7 53.1 210 19 10 3.3 1.8 | 13.4 56.1 195 17 9 8.0 4.4
7000 11.8 53.2 210 19 10 1.1 0.6 | 13.9 57.0 195 16 8 7.2 3.9
6750 11.9 53.4 210 18 9 0.4 0.2 | 14.5 58.1 195 16 8 9.0 4.9
6500 11.8 53.2 210 16 8 0.2 0.1 | 15.2 59.4 195 15 8 10.4 5.7
6250 11.8 53.2 210 14 7 1.4 0.7 | 16.0 60.8 190 14 7 10.2 5.6
6000 12.0 53.6 205 12 6 1.7 0.9 | 16.8 62.2 195 14 7 11.0 6.0
5750 12.1 53.8 205 9 5 4.1 2.3 | 17.6 63.7 195 13 7 9.6 5.2
5500 12.7 54.9 200 7 3 13.7 7.5 | 18.3 64.9 195 12 6 13.5 7.4
05/05/2024 at 1500 MDT | 05/05/2024 at 1800 MDT
|
CAPE... +25.7 LI... +0.2 | CAPE... +141.4 LI... -0.8
CINH... -1.8 K Index... +19.2 | CINH... -10.6 K Index... +22.2
|
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 -58.4 -73.1 230 38 20 -1.6 -0.9 | -57.7 -71.9 230 36 18 -2.0 -1.1
45000 -60.7 -77.3 235 49 25 -0.2 -0.1 | -60.5 -76.9 230 49 25 -0.1 -0.1
40000 -60.7 -77.3 245 70 36 0.3 0.1 | -60.4 -76.7 240 71 36 0.3 0.2
38000 -57.4 -71.3 245 69 36 7.5 4.1 | -57.2 -71.0 240 73 38 7.0 3.9
36000 -52.9 -63.2 245 66 34 7.5 4.1 | -53.0 -63.4 240 73 38 7.0 3.9
34000 -48.3 -54.9 240 62 32 8.1 4.5 | -48.5 -55.3 240 72 37 8.3 4.6
32000 -43.4 -46.1 240 56 29 8.1 4.5 | -43.5 -46.3 240 68 35 8.3 4.6
30000 -38.5 -37.3 235 50 26 8.4 4.6 | -38.5 -37.3 240 64 33 8.4 4.6
29000 -36.0 -32.8 235 48 25 8.3 4.6 | -36.0 -32.8 235 62 32 8.4 4.6
28000 -32.9 -27.2 235 45 23 8.3 4.6 | -32.9 -27.2 235 59 31 8.4 4.6
27000 -30.4 -22.7 230 44 23 8.1 4.4 | -30.5 -22.9 235 57 29 7.7 4.2
26000 -28.0 -18.4 235 47 24 8.1 4.4 | -28.2 -18.8 235 55 28 7.8 4.3
25000 -25.6 -14.1 235 49 25 8.1 4.5 | -25.9 -14.6 235 53 27 7.8 4.3
24000 -23.2 -9.8 235 50 26 6.9 3.8 | -23.6 -10.5 235 50 26 7.4 4.1
23000 -21.2 -6.2 235 48 25 6.8 3.7 | -21.4 -6.5 230 47 24 7.3 4.0
22000 -19.3 -2.7 235 46 24 6.8 3.7 | -19.3 -2.7 230 43 22 7.4 4.0
21000 -17.3 0.9 240 44 23 5.6 3.1 | -17.1 1.2 230 41 21 6.6 3.6
20000 -15.7 3.7 235 42 22 5.8 3.2 | -15.2 4.6 225 39 20 6.7 3.7
19500 -14.8 5.4 235 42 21 5.8 3.2 | -14.2 6.4 220 39 20 6.7 3.7
19000 -14.0 6.8 235 41 21 5.8 3.2 | -13.2 8.2 220 38 20 6.7 3.7
18500 -13.1 8.4 235 40 20 6.2 3.4 | -12.2 10.0 220 38 19 7.1 3.9
18000 -12.2 10.0 235 38 20 6.3 3.5 | -11.2 11.8 215 37 19 7.3 4.0
17500 -11.3 11.7 230 36 19 6.4 3.5 | -10.1 13.8 215 37 19 7.3 4.0
17000 -10.3 13.5 230 35 18 7.1 3.9 | -9.0 15.8 215 37 19 7.1 3.9
16500 -9.2 15.4 225 34 17 7.0 3.9 | -8.0 17.6 210 37 19 7.1 3.9
16000 -8.1 17.4 225 32 17 7.8 4.3 | -6.9 19.6 210 37 19 7.6 4.2
15500 -6.9 19.6 220 32 16 7.9 4.4 | -5.8 21.6 210 37 19 7.8 4.3
15000 -5.1 22.8 220 31 16 8.6 4.7 | -4.6 23.7 205 37 19 8.3 4.5
14500 -3.9 25.0 215 30 16 8.5 4.7 | -2.6 27.3 205 36 19 9.1 5.0
14000 -2.6 27.3 210 30 15 9.1 5.0 | -1.3 29.7 200 36 19 9.5 5.2
13500 -1.2 29.8 210 29 15 9.2 5.1 | 0.1 32.2 200 36 18 9.6 5.3
13000 0.1 32.2 205 28 15 9.3 5.1 | 1.6 34.9 200 35 18 9.5 5.2
12500 1.5 34.7 205 28 14 9.3 5.1 | 3.0 37.4 200 35 18 9.5 5.2
12000 2.9 37.2 200 27 14 9.6 5.2 | 4.4 39.9 195 35 18 9.5 5.2
11500 4.3 39.7 200 27 14 9.8 5.4 | 5.8 42.4 195 34 18 9.4 5.2
11000 5.8 42.4 200 26 14 9.3 5.1 | 7.2 45.0 190 34 18 9.0 5.0
10500 7.1 44.8 195 26 14 8.1 4.4 | 8.3 46.9 190 34 17 7.7 4.2
10250 7.7 45.9 195 26 14 11.1 6.1 | 9.0 48.2 190 34 17 10.3 5.6
10000 8.6 47.5 195 26 13 12.0 6.6 | 9.8 49.6 185 33 17 11.1 6.1
9750 9.4 48.9 195 26 13 9.6 5.2 | 10.5 50.9 185 33 17 9.4 5.1
9500 10.1 50.2 195 26 13 9.5 5.2 | 11.2 52.2 185 33 17 8.8 4.8
9250 10.8 51.4 195 26 13 9.9 5.4 | 11.9 53.4 185 32 17 9.7 5.3
9000 11.6 52.9 195 26 13 10.1 5.5 | 12.6 54.7 180 32 16 10.3 5.6
8750 12.3 54.1 190 25 13 9.7 5.3 | 13.3 55.9 180 32 16 9.3 5.1
8500 13.0 55.4 190 25 13 9.7 5.3 | 14.0 57.2 180 31 16 9.0 5.0
8250 13.8 56.8 190 25 13 9.6 5.3 | 14.7 58.5 180 31 16 8.6 4.7
8000 14.5 58.1 190 25 13 9.6 5.3 | 15.3 59.5 180 31 16 10.6 5.8
7750 15.2 59.4 190 25 13 9.8 5.4 | 16.2 61.2 180 30 15 10.9 6.0
7500 16.0 60.8 190 24 13 10.2 5.6 | 16.9 62.4 175 29 15 9.1 5.0
7250 16.7 62.1 190 24 12 9.4 5.1 | 17.6 63.7 175 29 15 9.9 5.4
7000 17.3 63.1 190 24 12 7.7 4.2 | 18.3 64.9 175 29 15 6.7 3.7
6750 17.9 64.2 190 24 12 9.9 5.4 | 18.7 65.7 175 29 15 8.2 4.5
6500 18.8 65.8 190 23 12 12.2 6.7 | 19.6 67.3 175 27 14 12.1 6.7
6250 19.7 67.5 185 23 12 10.8 5.9 | 20.4 68.7 175 26 13 10.5 5.8
6000 20.4 68.7 185 22 11 10.0 5.5 | 21.1 70.0 170 25 13 8.6 4.7
5750 21.2 70.2 185 21 11 9.6 5.3 | 21.7 71.1 170 24 12 8.8 4.8
5500 22.0 71.6 185 19 10 14.5 7.9 | 22.4 72.3 170 20 10 12.3 6.7
________________________________________________________________________________
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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