Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
907
UXUS97 KBOU 141315
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0715 MDT Saturday, September 14, 2024
This forecast is for Saturday, September 14, 2024:
If the trigger temperature of 76.7 F/24.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1351 ft/min (6.9 m/s)
Maximum height of thermals.................. 19896 ft MSL (14596 ft AGL)
Forecast maximum temperature................... 89.0 F/32.1 C
Time of trigger temperature.................... 1045 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................. 13832 ft MSL (8532 ft AGL)
Thermal soaring outlook for Sunday 09/15....... 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)................ Weak PVA
Potential height of wave....................... 46112 ft MSL (40812 ft AGL)
Wave soaring outlook for Sunday 09/15.......... Fair
Remarks...
Sunrise/Sunset.................... 06:40:27 / 19:09:07 MDT
Total possible sunshine........... 12 hr 28 min 40 sec (748 min 40 sec)
Altitude of sun at 12:54:47 MDT... 53.21 degrees
Upper air data from numerical model forecast valid on 09/14/2024 at 0600 MDT
Freezing level.................. 14902 ft MSL (9602 ft AGL)
Convective condensation level... 14507 ft MSL (9207 ft AGL)
Lifted condensation level....... 15821 ft MSL (10521 ft AGL)
Lifted index.................... -6.0
K index......................... +18.7
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 -59.4 -74.9 260 36 18 1.2 0.6 M M M M M
45000 -56.8 -70.2 255 48 25 3.1 1.7 M M M M M
40000 -52.2 -62.0 260 44 22 2.9 1.6 M M M M M
38000 -50.5 -58.9 260 37 19 2.9 1.6 M M M M M
36000 -48.7 -55.7 260 31 16 2.9 1.6 M M M M M
34000 -45.1 -49.2 265 26 14 7.6 4.2 M M M M M
32000 -40.5 -40.9 265 23 12 7.6 4.2 M M M M M
30000 -35.0 -31.0 265 23 12 8.4 4.6 40.1 104.2 6.4 M M
29000 -32.5 -26.5 265 24 12 8.4 4.6 39.6 103.3 6.1 M M
28000 -30.0 -22.0 265 25 13 8.3 4.5 39.2 102.6 5.9 M M
27000 -27.6 -17.7 265 25 13 7.8 4.3 38.4 101.1 5.3 M M
26000 -25.3 -13.5 260 25 13 7.8 4.3 37.6 99.7 4.7 M M
25000 -23.0 -9.4 260 25 13 7.8 4.3 37.0 98.6 4.3 M M
24000 -20.9 -5.6 255 26 13 6.9 3.8 36.0 96.8 3.5 M M
23000 -18.8 -1.8 255 26 14 6.9 3.8 34.9 94.8 2.6 M M
22000 -16.8 1.8 250 27 14 6.8 3.7 33.9 93.1 1.8 M M
21000 -14.7 5.5 250 26 14 7.1 3.9 32.9 91.2 1.0 M M
20000 -12.6 9.3 250 25 13 7.2 3.9 32.0 89.5 0.1 M M
19500 -11.6 11.1 245 25 13 7.2 3.9 31.6 88.8 -0.3 1320 6.7
19000 -10.5 13.1 245 24 12 9.1 5.0 31.2 88.2 -0.6 1272 6.5
18500 -9.0 15.8 245 23 12 9.8 5.3 31.2 88.2 -0.6 1213 6.2
18000 -7.5 18.5 245 21 11 9.7 5.3 31.3 88.3 -0.6 1155 5.9
17500 -6.3 20.7 245 20 11 7.4 4.0 31.0 87.8 -0.8 1103 5.6
17000 -5.2 22.6 245 19 10 7.5 4.1 30.6 87.1 -1.2 1055 5.4
16500 -4.1 24.6 250 18 9 7.7 4.2 30.3 86.5 -1.5 1006 5.1
16000 -2.9 26.8 245 17 9 7.8 4.3 29.9 85.9 -1.9 958 4.9
15500 -1.2 29.8 245 16 8 8.5 4.7 29.5 85.1 -2.3 884 4.5
15000 0.0 32.0 245 16 8 8.5 4.7 29.3 84.7 -2.6 832 4.2
14500 1.3 34.3 250 15 8 8.7 4.8 29.1 84.4 -2.8 779 4.0
14000 2.6 36.7 250 15 8 8.8 4.8 28.9 84.1 -3.0 726 3.7
13500 3.9 39.0 255 15 8 8.7 4.8 28.8 83.8 -3.1 672 3.4
13000 5.2 41.4 255 15 7 8.5 4.7 28.6 83.4 -3.4 619 3.1
12500 6.4 43.5 255 14 7 8.2 4.5 28.4 83.1 -3.6 567 2.9
12000 7.5 45.5 250 14 7 7.0 3.9 28.0 82.4 -4.0 520 2.6
11500 8.5 47.3 245 13 7 7.2 3.9 27.6 81.7 -4.5 475 2.4
11000 9.6 49.3 240 13 7 8.0 4.4 27.3 81.1 -4.9 427 2.2
10500 10.7 51.3 240 12 6 5.5 3.0 27.0 80.6 -5.2 378 1.9
10250 11.0 51.8 235 12 6 3.8 2.1 26.5 79.7 -5.7 364 1.8
10000 11.4 52.5 235 12 6 7.8 4.3 26.2 79.2 -6.0 344 1.7
9750 12.0 53.6 235 11 6 8.8 4.8 26.1 79.0 -6.2 319 1.6
9500 12.5 54.5 230 10 5 8.0 4.4 26.0 78.9 -6.4 295 1.5
9250 13.0 55.4 225 10 5 5.9 3.2 25.8 78.5 -6.6 273 1.4
9000 13.4 56.1 225 9 5 6.4 3.5 25.5 77.9 -7.0 255 1.3
8750 13.8 56.8 225 9 4 7.9 4.3 25.3 77.6 -7.3 233 1.2
8500 14.3 57.7 220 8 4 7.3 4.0 25.2 77.3 -7.5 211 1.1
8250 14.8 58.6 220 7 4 6.8 3.7 25.0 76.9 -7.8 190 1.0
8000 15.2 59.4 220 7 4 6.5 3.6 24.7 76.5 -8.2 170 0.9
7750 15.7 60.3 220 7 3 6.9 3.8 24.5 76.1 -8.5 149 0.8
7500 16.1 61.0 220 6 3 5.1 2.8 24.2 75.6 -8.8 129 0.7
7250 16.4 61.5 220 6 3 3.2 1.7 23.8 74.8 -9.2 112 0.6
7000 16.7 62.1 220 5 3 3.7 2.0 23.3 73.9 -9.7 96 0.5
6750 17.0 62.6 220 4 2 3.2 1.7 22.8 73.1 -10.1 80 0.4
6500 17.1 62.8 220 4 2 -3.0 -1.7 22.2 71.9 -10.8 69 0.4
6250 16.7 62.1 225 3 1 -7.0 -3.9 20.9 69.7 -11.9 73 0.4
6000 16.3 61.3 230 1 1 -5.8 -3.2 19.7 67.5 -13.1 77 0.4
5750 15.9 60.6 000 0 0 -8.2 -4.5 18.5 65.3 -14.2 83 0.4
5500 15.1 59.2 195 1 0 -10.4 -5.7 17.0 62.7 -15.8 99 0.5
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
09/14/2024 at 0900 MDT | 09/14/2024 at 1200 MDT
|
CAPE... 0.0 LI... -0.0 | CAPE... +6.3 LI... +0.6
CINH... 0.0 K Index... +8.9 | CINH... -44.8 K Index... +4.1
|
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 -59.8 -75.6 270 35 18 1.8 1.0 | -59.9 -75.8 265 30 15 1.5 0.8
45000 -56.9 -70.4 270 47 24 2.0 1.1 | -57.5 -71.5 275 42 22 1.4 0.8
40000 -53.8 -64.8 280 39 20 4.3 2.3 | -55.2 -67.4 285 38 19 6.1 3.3
38000 -51.2 -60.2 285 35 18 4.3 2.4 | -51.7 -61.1 290 35 18 5.8 3.2
36000 -48.7 -55.7 290 32 16 4.3 2.4 | -48.3 -54.9 295 33 17 5.8 3.2
34000 -44.7 -48.5 290 29 15 7.7 4.2 | -43.9 -47.0 290 31 16 8.0 4.4
32000 -40.0 -40.0 280 28 14 7.8 4.3 | -38.5 -37.3 285 30 15 7.9 4.3
30000 -34.6 -30.3 275 25 13 8.1 4.4 | -33.8 -28.8 280 27 14 7.9 4.3
29000 -32.2 -26.0 275 24 12 8.1 4.4 | -31.4 -24.5 275 26 13 7.9 4.3
28000 -29.8 -21.6 275 22 11 7.9 4.3 | -29.1 -20.4 270 25 13 7.7 4.2
27000 -27.6 -17.7 270 22 11 7.5 4.1 | -26.8 -16.2 265 24 13 7.5 4.1
26000 -25.3 -13.5 265 21 11 7.5 4.1 | -24.6 -12.3 265 24 12 7.5 4.1
25000 -23.1 -9.6 260 21 11 7.5 4.1 | -22.3 -8.1 260 24 12 7.5 4.1
24000 -20.9 -5.6 255 22 11 7.2 3.9 | -20.2 -4.4 255 24 12 7.1 3.9
23000 -18.8 -1.8 255 23 12 7.2 4.0 | -18.0 -0.4 255 24 12 7.1 3.9
22000 -16.6 2.1 255 25 13 7.2 3.9 | -15.9 3.4 255 24 12 7.1 3.9
21000 -14.4 6.1 250 24 12 7.5 4.1 | -13.8 7.2 250 23 12 6.9 3.8
20000 -12.2 10.0 250 23 12 7.5 4.1 | -11.8 10.8 245 22 11 7.0 3.8
19500 -11.1 12.0 245 22 12 7.5 4.1 | -10.8 12.6 245 22 11 6.9 3.8
19000 -10.0 14.0 245 22 11 8.8 4.8 | -9.7 14.5 240 21 11 8.7 4.8
18500 -8.6 16.5 240 20 10 9.1 5.0 | -8.3 17.1 240 19 10 9.1 5.0
18000 -7.3 18.9 240 18 9 9.0 4.9 | -6.9 19.6 235 17 9 8.9 4.9
17500 -6.0 21.2 240 16 8 8.1 4.5 | -5.7 21.7 230 15 8 7.7 4.2
17000 -4.8 23.4 245 14 7 8.3 4.5 | -4.6 23.7 225 13 7 7.9 4.3
16500 -3.6 25.5 245 12 6 6.9 3.8 | -3.0 26.6 215 11 5 6.3 3.5
16000 -2.1 28.2 250 9 5 6.5 3.6 | -2.0 28.4 210 9 5 6.3 3.4
15500 -1.1 30.0 250 7 4 7.8 4.3 | -1.0 30.2 200 8 4 7.4 4.1
15000 0.1 32.2 255 6 3 7.8 4.3 | 0.1 32.2 195 7 4 7.3 4.0
14500 1.2 34.2 255 5 3 7.9 4.3 | 1.2 34.2 190 7 3 8.1 4.4
14000 2.4 36.3 265 5 2 7.9 4.3 | 2.4 36.3 185 6 3 8.3 4.6
13500 3.6 38.5 275 4 2 8.0 4.4 | 3.6 38.5 185 5 3 8.2 4.5
13000 4.7 40.5 290 4 2 8.2 4.5 | 4.8 40.6 190 4 2 8.0 4.4
12500 5.9 42.6 300 5 2 8.1 4.5 | 6.0 42.8 195 2 1 8.2 4.5
12000 7.1 44.8 310 5 3 8.0 4.4 | 7.2 45.0 230 1 1 8.5 4.7
11500 8.2 46.8 315 6 3 8.0 4.4 | 8.5 47.3 290 2 1 8.5 4.7
11000 9.4 48.9 315 6 3 7.8 4.3 | 9.8 49.6 305 3 1 8.4 4.6
10500 10.6 51.1 315 6 3 5.3 2.9 | 11.1 52.0 315 4 2 4.5 2.5
10250 10.8 51.4 315 6 3 5.0 2.7 | 11.2 52.2 315 4 2 4.8 2.7
10000 11.4 52.5 310 6 3 9.4 5.2 | 11.9 53.4 315 5 2 10.7 5.9
9750 12.1 53.8 310 6 3 9.9 5.4 | 12.7 54.9 315 5 3 9.8 5.4
9500 12.8 55.0 310 6 3 8.9 4.9 | 13.4 56.1 315 6 3 9.3 5.1
9250 13.3 55.9 305 6 3 7.0 3.8 | 14.0 57.2 315 6 3 7.9 4.4
9000 13.8 56.8 305 5 3 7.1 3.9 | 14.6 58.3 320 6 3 8.1 4.4
8750 14.3 57.7 300 5 2 7.9 4.3 | 15.2 59.4 320 5 3 8.4 4.6
8500 14.9 58.8 295 4 2 7.3 4.0 | 15.9 60.6 325 5 3 8.2 4.5
8250 15.3 59.5 290 4 2 6.9 3.8 | 16.4 61.5 325 4 2 8.3 4.5
8000 15.8 60.4 280 3 2 6.8 3.7 | 17.0 62.6 330 3 2 7.7 4.2
7750 16.2 61.2 270 3 1 7.2 4.0 | 17.5 63.5 335 3 1 6.5 3.6
7500 16.7 62.1 260 2 1 4.9 2.7 | 17.9 64.2 340 2 1 8.0 4.4
7250 16.9 62.4 260 2 1 2.6 1.4 | 18.5 65.3 335 2 1 9.2 5.1
7000 17.1 62.8 255 2 1 3.5 1.9 | 19.1 66.4 335 1 1 9.3 5.1
6750 17.3 63.1 255 2 1 2.5 1.4 | 19.8 67.6 335 1 1 10.6 5.8
6500 17.3 63.1 255 3 1 -1.3 -0.7 | 20.6 69.1 335 1 1 10.7 5.9
6250 17.2 63.0 255 3 1 -1.9 -1.0 | 21.4 70.5 330 1 1 11.1 6.1
6000 17.1 62.8 255 2 1 -5.3 -2.9 | 22.2 72.0 330 1 1 8.9 4.9
5750 16.8 62.2 245 2 1 1.4 0.8 | 22.9 73.2 325 1 1 14.0 7.7
5500 17.7 63.9 245 2 1 25.3 13.9 | 24.5 76.1 330 1 1 29.5 16.2
09/14/2024 at 1500 MDT | 09/14/2024 at 1800 MDT
|
CAPE... 0.0 LI... +1.3 | CAPE... +9.0 LI... 0.0
CINH... 0.0 K Index... +8.3 | CINH... -23.2 K Index... +19.8
|
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 -60.2 -76.4 255 28 15 1.8 1.0 | -61.5 -78.7 260 32 16 1.3 0.7
45000 -57.5 -71.5 270 35 18 1.6 0.9 | -58.9 -74.0 270 31 16 2.6 1.4
40000 -54.7 -66.5 295 33 17 6.3 3.4 | -54.6 -66.3 300 15 8 6.6 3.6
38000 -51.3 -60.3 300 30 15 5.8 3.2 | -50.8 -59.4 310 13 7 6.4 3.5
36000 -47.8 -54.0 305 27 14 5.8 3.2 | -47.0 -52.6 325 12 6 6.4 3.5
34000 -43.3 -45.9 305 26 13 8.1 4.5 | -42.3 -44.1 320 12 6 8.1 4.4
32000 -37.8 -36.0 300 25 13 8.1 4.4 | -37.5 -35.5 315 12 6 8.1 4.4
30000 -33.1 -27.6 290 25 13 7.8 4.3 | -32.2 -26.0 300 15 8 7.8 4.3
29000 -30.8 -23.4 285 25 13 7.8 4.3 | -29.9 -21.8 295 17 9 7.8 4.3
28000 -28.5 -19.3 285 25 13 7.7 4.2 | -27.6 -17.7 290 19 10 7.7 4.2
27000 -26.2 -15.2 280 25 13 7.5 4.1 | -25.3 -13.5 290 22 11 7.7 4.2
26000 -24.0 -11.2 275 25 13 7.5 4.1 | -23.0 -9.4 290 24 12 7.7 4.2
25000 -21.7 -7.1 270 26 13 7.6 4.2 | -20.7 -5.3 285 26 13 7.8 4.3
24000 -19.6 -3.3 265 26 13 6.8 3.7 | -18.8 -1.8 285 27 14 6.1 3.4
23000 -17.6 0.3 265 26 13 6.8 3.7 | -16.9 1.6 280 28 14 6.1 3.4
22000 -15.6 3.9 260 25 13 6.8 3.7 | -15.1 4.8 280 29 15 6.2 3.4
21000 -13.6 7.5 260 25 13 6.7 3.7 | -13.2 8.2 275 27 14 6.7 3.7
20000 -11.6 11.1 260 24 13 6.7 3.7 | -11.3 11.7 265 25 13 6.9 3.8
19500 -10.6 12.9 255 24 13 6.6 3.6 | -10.4 13.3 265 24 12 6.9 3.8
19000 -9.6 14.7 255 24 12 8.2 4.5 | -9.4 15.1 260 23 12 8.1 4.5
18500 -8.3 17.1 255 22 11 8.5 4.7 | -8.2 17.2 260 21 11 8.3 4.5
18000 -7.0 19.4 255 20 10 8.5 4.7 | -7.0 19.4 255 20 10 8.1 4.4
17500 -5.2 22.6 255 18 9 8.3 4.5 | -5.9 21.4 255 20 10 7.0 3.9
17000 -3.9 25.0 250 16 8 8.2 4.5 | -4.8 23.4 250 20 10 6.9 3.8
16500 -2.7 27.1 245 15 8 8.0 4.4 | -3.6 25.5 245 19 10 9.3 5.1
16000 -1.5 29.3 240 14 7 8.1 4.4 | -1.4 29.5 240 18 9 9.5 5.2
15500 -0.4 31.3 235 13 7 7.6 4.2 | -0.0 32.0 235 17 9 8.9 4.9
15000 0.8 33.4 230 12 6 7.6 4.2 | 1.3 34.3 225 16 8 8.9 4.9
14500 1.9 35.4 225 11 6 7.5 4.1 | 2.7 36.9 220 15 8 8.6 4.7
14000 3.0 37.4 215 11 6 7.5 4.1 | 3.9 39.0 215 14 7 8.5 4.6
13500 4.1 39.4 205 10 5 7.9 4.4 | 5.2 41.4 205 13 7 8.5 4.7
13000 5.3 41.5 200 9 5 8.4 4.6 | 6.5 43.7 200 12 6 8.6 4.7
12500 6.5 43.7 185 8 4 8.6 4.7 | 7.8 46.0 195 11 6 8.7 4.8
12000 7.8 46.0 175 7 3 8.9 4.9 | 9.1 48.4 185 10 5 9.0 5.0
11500 9.1 48.4 165 6 3 8.9 4.9 | 10.4 50.7 180 9 4 8.9 4.9
11000 10.4 50.7 155 5 2 8.4 4.6 | 11.6 52.9 170 7 4 8.0 4.4
10500 11.6 52.9 150 4 2 4.9 2.7 | 12.8 55.0 160 6 3 4.4 2.4
10250 11.9 53.4 145 4 2 6.4 3.5 | 13.0 55.4 155 6 3 5.8 3.2
10000 12.7 54.9 145 4 2 12.3 6.8 | 13.8 56.8 150 5 3 11.8 6.5
9750 13.5 56.3 145 4 2 10.9 6.0 | 14.6 58.3 145 5 3 10.4 5.7
9500 14.3 57.7 145 4 2 10.6 5.8 | 15.3 59.5 145 5 2 10.0 5.5
9250 15.0 59.0 145 3 2 9.3 5.1 | 16.0 60.8 140 4 2 8.6 4.7
9000 15.7 60.3 145 3 2 9.8 5.4 | 16.6 61.9 140 4 2 9.2 5.0
8750 16.5 61.7 145 3 2 10.3 5.6 | 17.4 63.3 135 4 2 9.7 5.3
8500 17.2 63.0 145 3 2 10.2 5.6 | 18.1 64.6 135 4 2 9.8 5.4
8250 18.0 64.4 145 3 2 10.4 5.7 | 18.8 65.8 135 3 2 10.7 5.9
8000 18.8 65.8 145 3 2 9.9 5.4 | 19.6 67.3 135 3 1 10.1 5.5
7750 19.5 67.1 145 3 2 8.9 4.9 | 20.3 68.5 130 3 1 9.2 5.0
7500 20.2 68.4 145 3 1 10.1 5.5 | 21.0 69.8 130 2 1 9.6 5.3
7250 21.0 69.8 145 3 1 11.4 6.2 | 21.8 71.2 130 2 1 9.9 5.4
7000 21.8 71.2 150 3 1 10.5 5.8 | 22.5 72.5 130 2 1 9.8 5.4
6750 22.5 72.5 150 3 1 9.0 4.9 | 23.2 73.8 130 2 1 9.8 5.4
6500 23.2 73.8 150 2 1 10.0 5.5 | 24.0 75.2 130 1 1 10.1 5.5
6250 24.0 75.2 150 2 1 11.9 6.5 | 24.7 76.5 130 1 1 10.4 5.7
6000 24.9 76.8 155 2 1 9.6 5.3 | 25.5 77.9 130 1 0 9.8 5.4
5750 25.6 78.1 155 2 1 12.7 7.0 | 26.2 79.2 130 1 0 9.8 5.4
5500 27.0 80.6 155 2 1 25.7 14.1 | 27.0 80.6 125 1 0 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.
042613