Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
587
UXUS97 KGJT 111307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Tuesday, March 11, 2025
This forecast is for Tuesday, March 11, 2025:
If the trigger temperature of 59.3 F/15.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 586 ft/min (3.0 m/s)
Maximum height of thermals.................. 14095 ft MSL (9256 ft AGL)
Forecast maximum temperature................... 66.0 F/19.3 C
Time of trigger temperature.................... 1230 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 11754 ft MSL (6914 ft AGL)
Thermal soaring outlook for Wednesday 03/12.... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:30:42 / 19:17:14 MDT
Total possible sunshine........... 11 hr 46 min 32 sec (706 min 32 sec)
Altitude of sun at 13:23:58 MDT... 47.14 degrees
Upper air data from rawinsonde observation taken on 03/11/2025 at 0600 MDT
Freezing level.................. 10042 ft MSL (5203 ft AGL)
Convective condensation level... 19288 ft MSL (14449 ft AGL)
Lifted condensation level....... 17858 ft MSL (13019 ft AGL)
Lifted index.................... +4.5
K index......................... -12.5
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 -53.9 -65.0 240 72 37 -5.6 -3.1 113.2 235.8 53.5 M M
45000 -56.2 -69.2 250 59 30 2.7 1.5 83.2 181.7 39.1 M M
40000 -53.1 -63.6 255 70 36 1.6 0.9 64.9 148.8 29.9 M M
38000 -54.8 -66.6 250 59 31 -9.5 -5.2 53.4 128.1 23.1 M M
36000 -60.5 -76.9 245 47 24 -10.3 -5.7 36.4 97.6 12.1 M M
34000 -57.8 -72.0 250 40 21 7.6 4.1 31.8 89.3 9.1 M M
32000 -52.1 -61.8 265 40 21 9.0 5.0 30.8 87.4 8.6 M M
30000 -46.8 -52.2 270 39 20 9.1 5.0 30.1 86.1 8.3 M M
29000 -44.0 -47.2 270 38 20 9.0 5.0 29.8 85.6 8.2 M M
28000 -41.3 -42.3 270 36 19 9.1 5.0 29.5 85.1 8.1 M M
27000 -38.7 -37.7 270 37 19 9.2 5.0 29.1 84.4 7.9 M M
26000 -36.0 -32.8 265 37 19 9.1 5.0 28.9 84.0 7.8 M M
25000 -33.3 -27.9 270 35 18 8.3 4.6 28.6 83.4 7.7 M M
24000 -30.8 -23.4 270 35 18 7.9 4.3 28.0 82.4 7.3 M M
23000 -28.4 -19.1 270 36 18 7.8 4.3 27.4 81.3 6.9 M M
22000 -26.0 -14.8 270 32 17 7.8 4.3 26.6 79.9 6.4 M M
21000 -23.8 -10.8 260 27 14 4.8 2.7 25.7 78.3 5.7 M M
20000 -22.5 -8.5 260 23 12 4.2 2.3 23.9 75.0 4.2 M M
19500 -21.4 -6.5 260 23 12 9.8 5.4 23.4 74.2 3.8 M M
19000 -20.0 -4.0 255 21 11 9.3 5.1 23.3 74.0 3.8 M M
18500 -18.6 -1.5 250 22 11 8.8 4.8 23.2 73.8 3.7 M M
18000 -16.9 1.6 260 24 13 7.2 4.0 22.6 72.8 3.2 M M
17500 -16.1 3.0 260 25 13 4.1 2.3 21.9 71.4 2.6 M M
17000 -15.1 4.8 255 23 12 8.5 4.7 21.4 70.5 2.2 M M
16500 -13.9 7.0 260 20 10 8.3 4.6 21.1 70.0 1.9 M M
16000 -12.7 9.1 250 21 11 6.4 3.5 20.8 69.4 1.6 M M
15500 -11.9 10.6 235 22 11 5.6 3.1 20.1 68.2 1.0 M M
15000 -10.8 12.6 225 23 12 8.0 4.4 19.7 67.5 0.7 M M
14500 -9.7 14.5 220 22 11 7.3 4.0 19.2 66.6 0.3 M M
14000 -8.6 16.5 210 18 9 7.9 4.3 18.9 66.0 -0.1 772 3.9
13500 -7.3 18.9 220 19 10 10.5 5.8 18.8 65.8 -0.2 716 3.6
13000 -6.1 21.0 225 18 9 5.5 3.0 18.5 65.2 -0.5 665 3.4
12500 -5.2 22.6 230 16 8 5.5 3.0 17.9 64.2 -1.1 624 3.2
12000 -5.2 22.6 255 17 9 -1.3 -0.7 16.4 61.5 -2.5 608 3.1
11500 -4.2 24.4 255 19 10 10.9 6.0 15.9 60.6 -3.0 564 2.9
11000 -2.8 27.0 250 21 11 9.6 5.3 15.9 60.6 -3.0 507 2.6
10500 -1.3 29.7 250 17 9 9.5 5.2 15.8 60.5 -3.1 449 2.3
10250 -0.6 30.9 245 15 8 9.6 5.3 15.8 60.5 -3.1 420 2.1
10000 0.1 32.2 245 14 7 9.1 5.0 15.8 60.5 -3.1 391 2.0
9750 0.8 33.4 235 15 8 8.4 4.6 15.7 60.3 -3.2 364 1.9
9500 1.4 34.5 245 14 7 8.5 4.7 15.6 60.2 -3.3 338 1.7
9250 2.0 35.6 245 13 7 8.5 4.7 15.5 60.0 -3.4 311 1.6
9000 2.7 36.9 240 12 6 8.5 4.7 15.5 59.8 -3.5 285 1.4
8750 3.3 37.9 235 10 5 8.5 4.7 15.4 59.6 -3.6 258 1.3
8500 3.9 39.0 220 8 4 8.5 4.7 15.3 59.5 -3.7 232 1.2
8250 4.6 40.3 205 7 4 8.5 4.7 15.2 59.3 -3.8 206 1.0
8000 5.2 41.4 190 9 5 8.5 4.7 15.1 59.1 -3.9 179 0.9
7750 5.8 42.4 185 10 5 8.4 4.6 15.0 58.9 -4.0 153 0.8
7500 6.5 43.7 180 12 6 8.8 4.8 14.9 58.7 -4.2 126 0.6
7250 7.1 44.8 170 14 7 7.2 4.0 14.8 58.6 -4.3 100 0.5
7000 7.6 45.7 165 17 8 6.7 3.6 14.5 58.1 -4.5 78 0.4
6750 8.0 46.4 165 18 9 2.4 1.3 14.2 57.5 -4.9 58 0.3
6500 7.9 46.2 165 20 10 -1.9 -1.1 13.4 56.1 -5.7 53 0.3
6250 7.8 46.0 160 18 9 -0.8 -0.4 12.5 54.6 -6.5 48 0.2
6000 7.9 46.2 155 16 8 3.3 1.8 11.8 53.3 -7.2 40 0.2
5750 8.0 46.4 150 16 8 -6.0 -3.3 11.2 52.2 -7.9 29 0.1
5500 6.8 44.2 140 18 9 -19.9 -10.9 9.3 48.8 -9.8 57 0.3
5250 5.3 41.5 135 18 9 -19.5 -10.7 7.1 44.8 -12.1 96 0.5
5000 3.7 38.7 130 12 6 -20.5 -11.2 4.9 40.8 -14.4 135 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
03/11/2025 at 0900 MDT | 03/11/2025 at 1200 MDT
|
CAPE... 0.0 LI... +5.0 | CAPE... 0.0 LI... +4.6
CINH... -0.1 K Index... -8.7 | CINH... -0.3 K Index... -7.3
|
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 -56.2 -69.2 245 53 27 0.7 0.4 | -56.1 -69.0 245 52 27 0.0 0.0
45000 -55.1 -67.2 240 58 30 0.8 0.4 | -56.0 -68.8 240 57 30 0.0 0.0
40000 -54.4 -65.9 245 64 33 0.5 0.3 | -55.3 -67.5 245 61 31 0.5 0.3
38000 -54.8 -66.6 245 62 32 -2.4 -1.3 | -55.6 -68.1 240 59 30 -2.4 -1.3
36000 -56.2 -69.2 245 53 27 -2.4 -1.3 | -57.0 -70.6 235 50 26 -2.3 -1.3
34000 -57.4 -71.3 240 44 22 4.9 2.7 | -58.1 -72.6 230 43 22 5.8 3.2
32000 -52.5 -62.5 245 42 22 8.2 4.5 | -52.9 -63.2 235 42 22 8.7 4.8
30000 -47.5 -53.5 255 41 21 8.6 4.7 | -47.6 -53.7 235 42 21 9.1 5.0
29000 -45.0 -49.0 255 40 21 8.5 4.7 | -44.9 -48.8 235 39 20 8.9 4.9
28000 -42.4 -44.3 255 39 20 8.5 4.7 | -42.3 -44.1 240 37 19 8.9 4.9
27000 -39.9 -39.8 255 37 19 8.6 4.7 | -39.6 -39.3 240 35 18 9.0 4.9
26000 -36.8 -34.2 255 35 18 8.3 4.5 | -37.1 -34.8 235 33 17 8.3 4.6
25000 -34.3 -29.7 255 33 17 8.3 4.5 | -34.0 -29.2 235 31 16 8.3 4.6
24000 -31.8 -25.2 250 31 16 8.3 4.5 | -31.5 -24.7 230 30 15 8.2 4.5
23000 -29.3 -20.7 250 29 15 8.1 4.5 | -29.1 -20.4 230 29 15 7.9 4.4
22000 -26.9 -16.4 250 28 14 8.1 4.5 | -26.7 -16.1 235 28 15 7.9 4.4
21000 -24.4 -11.9 250 27 14 7.8 4.3 | -24.3 -11.7 235 28 14 7.7 4.2
20000 -22.1 -7.8 250 26 13 7.7 4.2 | -22.0 -7.6 235 26 13 7.5 4.1
19500 -21.0 -5.8 250 25 13 7.7 4.2 | -20.9 -5.6 240 25 13 7.5 4.1
19000 -19.8 -3.6 250 25 13 7.7 4.2 | -19.8 -3.6 240 24 13 7.5 4.1
18500 -18.7 -1.7 250 24 12 7.7 4.2 | -18.6 -1.5 240 24 12 7.6 4.2
18000 -17.5 0.5 250 24 12 7.7 4.2 | -17.5 0.5 245 23 12 7.7 4.2
17500 -16.4 2.5 250 23 12 7.7 4.2 | -16.3 2.7 245 23 12 7.8 4.3
17000 -15.2 4.6 250 23 12 7.6 4.2 | -15.2 4.6 245 22 11 7.3 4.0
16500 -14.1 6.6 245 22 12 7.6 4.2 | -14.1 6.6 245 22 11 7.3 4.0
16000 -13.0 8.6 245 22 11 7.0 3.8 | -13.0 8.6 245 21 11 6.7 3.7
15500 -12.0 10.4 245 22 11 6.8 3.7 | -12.0 10.4 245 21 11 6.5 3.6
15000 -11.0 12.2 245 21 11 6.5 3.5 | -11.1 12.0 240 21 11 6.2 3.4
14500 -10.1 13.8 245 21 11 6.0 3.3 | -10.2 13.6 240 20 10 5.9 3.2
14000 -9.2 15.4 245 20 10 6.0 3.3 | -9.4 15.1 240 20 10 6.0 3.3
13500 -8.3 17.1 245 20 10 6.1 3.3 | -8.4 16.9 240 20 10 6.5 3.6
13000 -7.4 18.7 245 19 10 6.1 3.4 | -7.5 18.5 240 19 10 6.6 3.6
12500 -6.4 20.5 245 19 10 7.1 3.9 | -6.5 20.3 235 19 10 7.5 4.1
12000 -5.4 22.3 245 19 10 7.1 3.9 | -5.4 22.3 235 18 9 7.4 4.1
11500 -4.3 24.3 245 19 10 8.0 4.4 | -4.2 24.4 235 18 9 8.0 4.4
11000 -3.1 26.4 245 19 10 7.9 4.4 | -3.1 26.4 235 17 9 7.9 4.4
10500 -2.1 28.2 245 18 9 6.2 3.4 | -2.0 28.4 230 16 8 6.4 3.5
10250 -1.6 29.1 240 18 9 6.4 3.5 | -1.5 29.3 230 16 8 7.1 3.9
10000 -1.0 30.2 240 17 9 11.0 6.0 | -0.9 30.4 230 16 8 10.3 5.6
9750 -0.1 31.8 240 16 8 10.5 5.8 | -0.1 31.8 225 15 7 9.0 4.9
9500 0.5 32.9 240 16 8 6.5 3.5 | 0.4 32.7 225 14 7 6.4 3.5
9250 1.0 33.8 235 15 8 8.1 4.4 | 0.9 33.6 225 13 7 6.6 3.6
9000 1.9 35.4 235 13 7 5.4 3.0 | 1.5 34.7 220 12 6 8.7 4.8
8750 2.4 36.3 230 12 6 7.3 4.0 | 2.7 36.9 215 11 6 6.9 3.8
8500 2.9 37.2 220 11 6 7.1 3.9 | 3.3 37.9 215 10 5 8.1 4.4
8250 3.5 38.3 215 11 6 5.9 3.2 | 3.8 38.8 210 10 5 5.5 3.0
8000 3.8 38.8 215 9 5 5.0 2.7 | 4.2 39.6 205 8 4 6.5 3.6
7750 4.2 39.6 205 9 5 5.7 3.1 | 4.9 40.8 200 8 4 9.8 5.4
7500 4.6 40.3 195 9 4 5.3 2.9 | 5.5 41.9 200 8 4 8.5 4.7
7250 5.0 41.0 185 9 5 4.9 2.7 | 6.1 43.0 195 7 4 5.5 3.0
7000 5.4 41.7 180 9 5 4.4 2.4 | 6.5 43.7 185 6 3 8.3 4.6
6750 5.7 42.3 175 9 5 4.9 2.7 | 7.4 45.3 190 6 3 12.8 7.0
6500 6.0 42.8 165 9 5 2.5 1.4 | 8.2 46.8 190 6 3 10.4 5.7
6250 6.1 43.0 160 8 4 -0.5 -0.3 | 9.0 48.2 185 6 3 9.7 5.3
6000 6.1 43.0 155 8 4 2.0 1.1 | 9.7 49.5 180 5 3 8.7 4.8
5750 6.2 43.2 150 6 3 -1.4 -0.8 | 10.4 50.7 185 5 3 12.6 6.9
5500 5.0 41.0 125 4 2 -39.2 -21.5 | 12.4 54.3 180 4 2 52.4 28.8
5250 M M M M M M M | M M M M M M M
5000 M M M M M M M | M M M M M M M
03/11/2025 at 1500 MDT | 03/11/2025 at 1800 MDT
|
CAPE... 0.0 LI... +3.0 | CAPE... +0.2 LI... +1.8
CINH... -0.0 K Index... +5.2 | CINH... -0.1 K Index... +12.6
|
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 -55.5 -67.9 245 49 25 -0.1 -0.1 | -55.2 -67.4 255 42 22 0.2 0.1
45000 -55.6 -68.1 240 58 30 -0.1 -0.1 | -55.0 -67.0 245 55 29 0.2 0.1
40000 -55.5 -67.9 245 55 28 0.1 0.1 | -54.5 -66.1 245 51 26 0.3 0.2
38000 -55.9 -68.6 240 50 26 -1.9 -1.0 | -54.7 -66.5 245 46 24 -1.3 -0.7
36000 -57.0 -70.6 235 41 21 -1.9 -1.0 | -55.5 -67.9 240 37 19 -1.3 -0.7
34000 -57.9 -72.2 225 33 17 5.0 2.8 | -56.2 -69.2 240 28 14 2.5 1.4
32000 -52.8 -63.0 225 33 17 8.6 4.7 | -52.5 -62.5 235 24 12 6.2 3.4
30000 -47.6 -53.7 225 32 16 9.3 5.1 | -48.7 -55.7 225 20 10 8.4 4.6
29000 -44.9 -48.8 225 31 16 9.2 5.0 | -46.0 -50.8 225 21 11 9.1 5.0
28000 -42.1 -43.8 220 31 16 9.2 5.0 | -43.3 -45.9 230 22 11 9.1 5.0
27000 -39.4 -38.9 220 30 16 9.3 5.1 | -40.6 -41.1 235 23 12 9.1 5.0
26000 -37.0 -34.6 220 30 15 7.6 4.2 | -38.0 -36.4 235 24 13 8.4 4.6
25000 -34.7 -30.5 220 29 15 7.6 4.2 | -35.5 -31.9 240 26 14 8.4 4.6
24000 -31.9 -25.4 220 28 15 7.6 4.2 | -33.0 -27.4 240 28 15 8.4 4.6
23000 -29.5 -21.1 220 27 14 7.9 4.4 | -30.1 -22.2 240 28 15 7.3 4.0
22000 -27.1 -16.8 225 26 14 7.9 4.4 | -27.9 -18.2 240 28 14 7.3 4.0
21000 -24.7 -12.5 225 26 13 7.6 4.2 | -25.8 -14.4 240 27 14 7.1 3.9
20000 -22.5 -8.5 225 25 13 7.4 4.0 | -23.7 -10.7 240 26 13 6.9 3.8
19500 -21.4 -6.5 230 24 12 7.4 4.0 | -22.7 -8.9 235 25 13 6.9 3.8
19000 -20.3 -4.5 230 23 12 7.4 4.0 | -21.6 -6.9 235 24 13 6.9 3.8
18500 -19.2 -2.6 230 23 12 7.4 4.0 | -20.6 -5.1 235 24 12 6.8 3.7
18000 -18.1 -0.6 230 22 12 7.3 4.0 | -19.6 -3.3 230 23 12 6.4 3.5
17500 -17.0 1.4 230 22 11 7.4 4.1 | -18.7 -1.7 230 22 11 6.4 3.5
17000 -16.0 3.2 230 21 11 6.5 3.6 | -17.7 0.1 225 22 11 7.5 4.1
16500 -15.0 5.0 230 21 11 6.6 3.6 | -16.6 2.1 225 21 11 7.5 4.1
16000 -14.0 6.8 230 20 10 6.1 3.4 | -15.5 4.1 220 20 10 8.0 4.4
15500 -13.2 8.2 230 19 10 6.0 3.3 | -14.2 6.4 220 19 10 8.3 4.6
15000 -12.3 9.9 225 19 10 6.3 3.4 | -13.0 8.6 220 19 10 8.5 4.6
14500 -11.4 11.5 225 18 9 6.9 3.8 | -11.7 10.9 220 18 9 8.8 4.8
14000 -10.4 13.3 225 17 9 7.1 3.9 | -10.4 13.3 220 18 9 8.8 4.8
13500 -9.2 15.4 220 17 9 8.4 4.6 | -9.1 15.6 220 18 9 9.5 5.2
13000 -8.0 17.6 220 16 8 8.3 4.5 | -7.7 18.1 220 17 9 9.4 5.2
12500 -6.7 19.9 220 15 8 8.9 4.9 | -6.3 20.7 220 17 9 9.2 5.1
12000 -5.4 22.3 220 15 8 8.9 4.9 | -4.9 23.2 220 17 9 9.3 5.1
11500 -4.1 24.6 220 15 8 9.2 5.0 | -3.5 25.7 225 16 8 8.9 4.9
11000 -2.7 27.1 225 14 7 9.3 5.1 | -2.2 28.0 225 16 8 9.1 5.0
10500 -1.5 29.3 225 13 7 7.2 4.0 | -0.9 30.4 225 16 8 7.3 4.0
10250 -0.9 30.4 225 13 7 8.6 4.7 | -0.4 31.3 230 15 8 8.4 4.6
10000 -0.1 31.8 225 13 7 11.8 6.5 | 0.3 32.5 230 15 8 10.8 5.9
9750 0.8 33.4 225 13 7 10.3 5.7 | 1.2 34.2 230 15 8 9.9 5.4
9500 1.4 34.5 225 12 6 8.0 4.4 | 1.8 35.2 235 15 8 8.3 4.5
9250 2.0 35.6 230 11 6 8.3 4.5 | 2.4 36.3 235 15 8 8.5 4.7
9000 2.7 36.9 230 10 5 9.6 5.3 | 3.1 37.6 240 14 7 9.3 5.1
8750 4.1 39.4 230 11 6 8.8 4.8 | 4.5 40.1 240 14 7 8.6 4.7
8500 4.8 40.6 230 10 5 9.2 5.1 | 5.1 41.2 240 13 7 9.0 4.9
8250 5.5 41.9 235 10 5 8.9 4.9 | 5.8 42.4 240 13 7 8.4 4.6
8000 6.1 43.0 240 8 4 9.4 5.2 | 6.4 43.5 245 13 7 8.5 4.7
7750 6.9 44.4 240 9 4 10.1 5.5 | 7.1 44.8 245 12 6 9.0 5.0
7500 7.6 45.7 240 9 5 9.9 5.4 | 7.7 45.9 245 12 6 9.1 5.0
7250 8.3 46.9 240 9 5 8.3 4.6 | 8.4 47.1 250 11 6 7.9 4.4
7000 8.9 48.0 245 8 4 9.2 5.1 | 9.0 48.2 255 12 6 8.8 4.8
6750 9.7 49.5 245 8 4 11.2 6.2 | 9.7 49.5 250 11 6 10.4 5.7
6500 10.6 51.1 240 8 4 10.5 5.8 | 10.5 50.9 250 10 5 10.1 5.5
6250 11.4 52.5 245 8 4 11.2 6.1 | 11.3 52.3 255 10 5 11.1 6.1
6000 12.1 53.8 250 7 4 8.7 4.8 | 12.1 53.8 255 11 6 9.0 4.9
5750 12.8 55.0 250 7 4 11.2 6.2 | 12.6 54.7 255 10 5 7.2 4.0
5500 15.0 59.0 255 6 3 63.2 34.7 | 13.8 56.8 260 9 4 34.1 18.7
5250 M M M M M M M | M M M M M M M
5000 M M M M M M M | M M M M M M M
________________________________________________________________________________
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 at Walker Field in Grand
Junction, Colorado at
North Latitude: 39 deg 07 min 00.001 sec
West Longitude: 108 deg 31 min 59.998 sec
Elevation: 4839 feet (1475 meters)
and may not be representative of other areas along the Western Slope of
Colorado. 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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