Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
232
UXUS97 KGJT 161306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Sunday, November 16, 2025
This forecast is for Sunday, November 16, 2025:
If the trigger temperature of 45.6 F/7.6 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 595 ft/min (3.0 m/s)
Maximum height of thermals.................. 18015 ft MSL (12408 ft AGL)
Forecast maximum temperature................... 65.0 F/18.8 C
Time of trigger temperature.................... None
Time of overdevelopment........................ 1400 MST
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 15350 ft MSL (9743 ft AGL)
Thermal soaring outlook for Monday 11/17....... Poor
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:59:03 / 16:58:53 MST
Total possible sunshine........... 9 hr 59 min 49 sec (599 min 49 sec)
Altitude of sun at 11:58:58 MST... 31.95 degrees
Upper air data from rawinsonde observation taken on 11/16/2025 at 0500 MST
Freezing level.................. 7536 ft MSL (1929 ft AGL)
Convective condensation level... 9216 ft MSL (3609 ft AGL)
Lifted condensation level....... 13709 ft MSL (8101 ft AGL)
Lifted index.................... -1.9
K index......................... +13.6
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 -55.9 -68.6 245 23 12 1.3 0.7 M M M M M
45000 -53.9 -65.0 255 32 16 1.2 0.6 M M M M M
40000 -52.9 -63.2 260 48 25 0.7 0.4 M M M M M
38000 -52.3 -62.1 265 54 28 1.5 0.8 M M M M M
36000 -51.4 -60.5 270 58 30 1.5 0.8 M M M M M
34000 -50.2 -58.4 270 63 32 5.8 3.2 M M M M M
32000 -46.6 -51.9 275 64 33 6.1 3.3 M M M M M
30000 -43.0 -45.4 275 64 33 5.7 3.1 33.3 91.9 11.2 M M
29000 -41.3 -42.3 275 60 31 5.6 3.1 31.5 88.7 10.0 M M
28000 -39.6 -39.3 275 56 29 5.6 3.1 29.8 85.7 8.9 M M
27000 -38.0 -36.4 280 53 27 5.5 3.0 28.4 83.1 7.8 M M
26000 -35.9 -32.6 280 50 26 7.5 4.1 27.2 81.0 7.0 M M
25000 -33.7 -28.7 285 47 24 7.5 4.1 26.3 79.3 6.3 M M
24000 -31.5 -24.7 290 45 23 7.5 4.1 25.5 77.9 5.8 M M
23000 -29.4 -20.9 290 43 22 6.7 3.7 24.5 76.1 5.0 M M
22000 -27.4 -17.3 285 42 21 6.7 3.7 23.4 74.0 4.1 M M
21000 -25.4 -13.7 280 40 21 6.7 3.7 22.3 72.2 3.3 M M
20000 -23.0 -9.4 280 39 20 6.2 3.4 20.7 69.3 2.0 M M
19500 -22.1 -7.8 280 38 19 6.2 3.4 20.1 68.2 1.4 M M
19000 -21.2 -6.2 280 37 19 6.2 3.4 19.5 67.1 0.9 M M
18500 -20.3 -4.5 280 36 19 6.3 3.5 18.9 66.1 0.4 M M
18000 -19.3 -2.7 275 35 18 6.7 3.7 18.4 65.1 -0.1 986 5.0
17500 -18.3 -0.9 275 34 17 6.7 3.7 17.8 64.1 -0.6 942 4.8
17000 -17.4 0.7 275 33 17 6.1 3.3 17.3 63.1 -1.1 899 4.6
16500 -16.5 2.3 275 32 16 6.1 3.3 16.6 62.0 -1.7 857 4.4
16000 -15.6 3.9 270 31 16 6.0 3.3 16.0 60.9 -2.2 815 4.1
15500 -14.7 5.5 270 30 15 5.9 3.2 15.4 59.7 -2.9 775 3.9
15000 -13.9 7.0 265 29 15 5.8 3.2 14.7 58.5 -3.5 734 3.7
14500 -13.0 8.6 265 28 15 5.6 3.1 14.1 57.3 -4.1 695 3.5
14000 -12.2 10.0 260 27 14 5.6 3.1 13.4 56.1 -4.8 655 3.3
13500 -11.4 11.5 260 27 14 5.3 2.9 12.7 54.8 -5.5 617 3.1
13000 -10.7 12.7 255 26 13 5.3 2.9 11.9 53.5 -6.3 579 2.9
12500 -9.9 14.2 255 25 13 5.9 3.3 11.3 52.3 -6.9 540 2.7
12000 -9.0 15.8 250 25 13 5.9 3.2 10.6 51.1 -7.6 500 2.5
11500 -8.1 17.4 250 25 13 6.4 3.5 10.1 50.1 -8.2 459 2.3
11000 -7.2 19.0 245 25 13 6.3 3.5 9.5 49.1 -8.8 417 2.1
10500 -6.3 20.7 245 24 12 6.2 3.4 9.0 48.2 -9.4 374 1.9
10250 -5.8 21.6 245 23 12 7.1 3.9 8.7 47.7 -9.7 353 1.8
10000 -5.3 22.5 240 22 11 7.8 4.3 8.6 47.4 -9.9 329 1.7
9750 -4.7 23.5 240 21 11 7.1 3.9 8.4 47.1 -10.1 305 1.6
9500 -4.2 24.4 240 20 11 7.0 3.8 8.1 46.7 -10.4 283 1.4
9250 -3.7 25.3 240 20 10 6.7 3.7 7.9 46.3 -10.6 260 1.3
9000 -3.2 26.2 235 18 9 6.7 3.7 7.7 45.8 -10.9 238 1.2
8750 -2.7 27.1 235 17 9 7.3 4.0 7.5 45.5 -11.1 215 1.1
8500 -2.2 28.0 230 16 8 7.8 4.3 7.3 45.1 -11.4 192 1.0
8250 -1.6 29.1 230 15 8 6.6 3.6 7.1 44.8 -11.6 168 0.9
8000 -1.2 29.8 230 13 7 6.6 3.6 6.9 44.3 -11.9 147 0.7
7750 -0.6 30.9 225 12 6 7.7 4.2 6.7 44.0 -12.1 123 0.6
7500 -0.1 31.8 225 11 6 7.7 4.2 6.5 43.7 -12.3 99 0.5
7250 0.5 32.9 225 10 5 6.5 3.6 6.3 43.4 -12.5 76 0.4
7000 0.9 33.6 225 8 4 6.0 3.3 6.0 42.9 -12.9 56 0.3
6750 1.4 34.5 225 7 4 6.9 3.8 5.8 42.4 -13.1 34 0.2
6500 1.9 35.4 220 6 3 6.7 3.7 5.6 42.0 -13.4 12 0.1
6250 2.3 36.1 220 5 2 5.2 2.8 5.3 41.6 -13.7 M M
6000 2.6 36.7 210 4 2 3.5 1.9 4.9 40.8 -14.2 M M
5750 2.9 37.2 210 3 1 4.7 2.6 4.4 40.0 -14.7 M M
5500 M M M M M M M M M M M M
5250 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
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/16/2025 at 0800 MST | 11/16/2025 at 1100 MST
|
CAPE... 0.0 LI... +0.8 | CAPE... +0.1 LI... +0.9
CINH... -0.0 K Index... +25.3 | CINH... -0.1 K Index... +25.4
|
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 -62.4 -80.3 230 36 19 0.2 0.1 | -61.8 -79.2 230 33 17 0.3 0.2
45000 -62.0 -79.6 230 45 23 1.7 0.9 | -61.2 -78.2 220 42 22 1.6 0.9
40000 -59.4 -74.9 220 56 29 1.0 0.5 | -58.9 -74.0 205 56 29 1.6 0.9
38000 -55.2 -67.4 220 58 30 8.0 4.4 | -54.9 -66.8 205 59 31 7.5 4.1
36000 -50.4 -58.7 220 59 31 8.0 4.4 | -50.5 -58.9 205 62 32 7.5 4.1
34000 -45.6 -50.1 220 61 32 8.1 4.4 | -45.9 -50.6 205 64 33 7.9 4.3
32000 -40.8 -41.4 220 64 33 8.1 4.4 | -41.2 -42.2 205 66 34 7.9 4.3
30000 -36.0 -32.8 220 63 33 7.6 4.2 | -36.6 -33.9 210 67 34 7.3 4.0
29000 -33.7 -28.7 220 61 32 7.6 4.2 | -34.4 -29.9 210 66 34 7.4 4.0
28000 -31.5 -24.7 220 59 31 7.6 4.2 | -32.2 -26.0 210 65 33 7.4 4.1
27000 -29.4 -20.9 220 57 30 4.5 2.4 | -30.1 -22.2 210 63 32 4.6 2.5
26000 -28.0 -18.4 220 55 28 4.8 2.6 | -28.8 -19.8 210 59 30 4.4 2.4
25000 -26.2 -15.2 215 51 26 4.8 2.7 | -27.5 -17.5 210 55 28 4.5 2.4
24000 -24.6 -12.3 215 49 25 6.9 3.8 | -25.7 -14.3 210 51 26 7.1 3.9
23000 -22.6 -8.7 215 46 24 6.7 3.7 | -23.7 -10.7 210 48 24 6.9 3.8
22000 -20.6 -5.1 215 43 22 6.8 3.7 | -21.7 -7.1 210 45 23 6.9 3.8
21000 -18.6 -1.5 215 40 21 7.2 4.0 | -19.5 -3.1 210 42 22 7.9 4.4
20000 -16.5 2.3 215 37 19 7.2 4.0 | -17.2 1.0 210 40 21 7.9 4.3
19500 -15.4 4.3 215 36 19 7.2 4.0 | -16.0 3.2 210 39 20 7.9 4.3
19000 -14.3 6.3 215 35 18 7.3 4.0 | -14.9 5.2 210 39 20 8.1 4.4
18500 -13.4 7.9 215 34 17 5.6 3.1 | -13.8 7.2 210 38 19 6.5 3.6
18000 -12.5 9.5 215 33 17 5.8 3.2 | -12.8 9.0 210 36 19 6.6 3.6
17500 -11.7 10.9 210 33 17 5.8 3.2 | -11.8 10.8 210 35 18 6.3 3.5
17000 -10.9 12.4 210 32 17 5.8 3.2 | -11.0 12.2 210 34 17 6.0 3.3
16500 -10.0 14.0 210 32 16 5.8 3.2 | -10.1 13.8 210 33 17 6.0 3.3
16000 -9.2 15.4 210 32 16 6.2 3.4 | -9.3 15.3 205 32 16 5.5 3.0
15500 -8.3 17.1 210 31 16 6.2 3.4 | -8.5 16.7 205 31 16 5.5 3.0
15000 -7.4 18.7 215 31 16 6.6 3.6 | -7.6 18.3 205 30 16 6.2 3.4
14500 -6.4 20.5 215 30 15 6.6 3.6 | -6.7 19.9 205 30 15 6.3 3.5
14000 -5.5 22.1 215 29 15 6.5 3.6 | -5.8 21.6 205 29 15 6.6 3.6
13500 -4.5 23.9 220 28 15 6.5 3.6 | -4.8 23.4 205 29 15 6.7 3.7
13000 -3.6 25.5 220 27 14 6.6 3.6 | -3.8 25.2 205 28 15 6.7 3.7
12500 -2.6 27.3 220 26 14 6.6 3.6 | -2.9 26.8 205 28 14 6.5 3.6
12000 -1.7 28.9 220 26 13 6.5 3.6 | -1.9 28.6 205 27 14 6.5 3.5
11500 -0.8 30.6 220 25 13 6.4 3.5 | -1.0 30.2 205 26 14 6.3 3.4
11000 0.2 32.4 220 24 12 6.2 3.4 | -0.1 31.8 205 25 13 6.0 3.3
10500 1.1 34.0 225 23 12 6.0 3.3 | 0.7 33.3 200 24 12 5.1 2.8
10250 1.5 34.7 225 22 11 6.4 3.5 | 1.1 34.0 200 23 12 6.9 3.8
10000 2.0 35.6 220 22 11 7.0 3.8 | 1.6 34.9 200 22 11 8.6 4.7
9750 2.5 36.5 220 21 11 7.2 4.0 | 2.2 36.0 195 21 11 7.2 3.9
9500 3.0 37.4 215 21 11 7.0 3.8 | 2.7 36.9 195 20 11 6.9 3.8
9250 3.6 38.5 215 20 10 7.7 4.2 | 3.2 37.8 195 20 10 6.8 3.7
9000 4.2 39.6 215 19 10 8.2 4.5 | 3.7 38.7 190 19 10 7.4 4.1
8750 5.3 41.5 210 17 9 6.6 3.6 | 4.3 39.7 190 18 9 8.2 4.5
8500 5.8 42.4 205 16 8 7.0 3.8 | 5.5 41.9 190 16 8 7.9 4.3
8250 6.4 43.5 205 15 8 7.5 4.1 | 6.1 43.0 185 16 8 7.1 3.9
8000 6.9 44.4 205 15 8 7.3 4.0 | 6.6 43.9 180 15 8 8.1 4.4
7750 7.5 45.5 195 14 7 7.3 4.0 | 7.3 45.1 180 14 7 9.4 5.2
7500 8.0 46.4 190 13 7 6.6 3.6 | 8.0 46.4 175 13 7 7.8 4.3
7250 8.5 47.3 185 13 7 5.8 3.2 | 8.5 47.3 170 13 7 5.7 3.2
7000 8.9 48.0 180 13 7 5.7 3.1 | 9.0 48.2 170 13 7 8.2 4.5
6750 9.4 48.9 175 12 6 4.7 2.6 | 9.7 49.5 165 12 6 10.2 5.6
6500 9.7 49.5 165 10 5 3.1 1.7 | 10.4 50.7 165 11 5 9.1 5.0
6250 9.9 49.8 160 10 5 1.7 0.9 | 11.1 52.0 160 11 5 9.1 5.0
6000 10.0 50.0 155 10 5 3.9 2.1 | 11.8 53.2 155 11 6 8.2 4.5
5750 10.2 50.4 140 6 3 -3.0 -1.6 | 12.4 54.3 160 9 5 9.9 5.4
5500 8.2 46.8 120 4 2 -66.0 -36.2 | 13.8 56.8 150 8 4 34.6 19.0
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
11/16/2025 at 1400 MST | 11/16/2025 at 1700 MST
|
CAPE... +38.3 LI... -0.2 | CAPE... +58.7 LI... +0.1
CINH... -12.0 K Index... +27.5 | CINH... -37.1 K Index... +26.0
|
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 -60.6 -77.1 220 35 18 0.8 0.4 | -58.6 -73.5 220 33 17 1.4 0.8
45000 -59.4 -74.9 215 47 24 1.2 0.7 | -56.3 -69.3 215 48 25 2.0 1.1
40000 -57.6 -71.7 200 64 33 1.1 0.6 | -53.3 -63.9 195 62 32 2.0 1.1
38000 -55.0 -67.0 200 68 35 6.2 3.4 | -52.2 -62.0 190 70 36 1.7 0.9
36000 -50.9 -59.6 195 71 37 6.2 3.4 | -51.1 -60.0 185 78 40 1.7 0.9
34000 -46.8 -52.2 195 74 38 7.8 4.3 | -49.5 -57.1 185 81 42 5.7 3.1
32000 -42.1 -43.8 195 75 39 7.8 4.3 | -46.0 -50.8 180 70 36 5.8 3.2
30000 -37.8 -36.0 195 74 38 5.9 3.2 | -42.3 -44.1 180 59 30 7.3 4.0
29000 -36.1 -33.0 200 71 36 5.8 3.2 | -40.1 -40.2 180 55 28 7.4 4.0
28000 -34.3 -29.7 200 67 35 5.9 3.2 | -37.9 -36.2 180 51 26 7.4 4.0
27000 -32.6 -26.7 200 64 33 5.7 3.1 | -35.7 -32.3 185 48 24 7.8 4.3
26000 -31.0 -23.8 205 59 30 5.6 3.0 | -33.2 -27.8 185 46 24 8.4 4.6
25000 -29.3 -20.7 205 54 28 5.6 3.1 | -30.7 -23.3 185 44 23 8.4 4.6
24000 -27.7 -17.9 205 49 25 6.3 3.4 | -28.2 -18.8 185 42 22 8.4 4.6
23000 -24.7 -12.5 205 46 24 8.3 4.6 | -25.9 -14.6 190 42 22 7.7 4.2
22000 -22.2 -8.0 200 44 23 8.3 4.6 | -23.0 -9.4 190 42 22 7.7 4.2
21000 -19.8 -3.6 200 42 22 7.3 4.0 | -20.8 -5.4 195 42 22 7.2 4.0
20000 -17.6 0.3 200 41 21 7.4 4.1 | -18.7 -1.7 195 41 21 7.2 4.0
19500 -16.5 2.3 195 40 21 7.4 4.1 | -17.6 0.3 195 41 21 7.3 4.0
19000 -15.4 4.3 195 39 20 7.5 4.1 | -16.5 2.3 195 41 21 7.3 4.0
18500 -14.4 6.1 195 39 20 6.5 3.6 | -15.5 4.1 195 40 21 7.3 4.0
18000 -13.5 7.7 195 39 20 6.4 3.5 | -14.4 6.1 195 40 20 7.3 4.0
17500 -12.5 9.5 195 38 20 6.5 3.6 | -13.3 8.1 195 39 20 7.3 4.0
17000 -11.6 11.1 190 38 19 6.8 3.8 | -12.3 9.9 195 39 20 6.6 3.6
16500 -10.6 12.9 190 37 19 6.9 3.8 | -11.4 11.5 195 39 20 6.6 3.6
16000 -9.6 14.7 190 37 19 6.6 3.6 | -10.4 13.3 195 38 20 6.7 3.7
15500 -8.6 16.5 190 37 19 6.6 3.6 | -9.4 15.1 195 38 20 6.7 3.7
15000 -7.7 18.1 190 36 19 6.5 3.6 | -8.5 16.7 195 38 20 6.7 3.7
14500 -6.8 19.8 190 35 18 6.5 3.5 | -7.5 18.5 200 38 19 6.6 3.6
14000 -5.8 21.6 185 34 18 6.5 3.6 | -6.5 20.3 200 37 19 6.6 3.6
13500 -4.9 23.2 185 33 17 6.6 3.6 | -5.6 21.9 200 37 19 6.4 3.5
13000 -3.9 25.0 185 31 16 6.7 3.7 | -4.7 23.5 200 37 19 6.4 3.5
12500 -3.0 26.6 185 30 15 6.7 3.7 | -3.8 25.2 200 36 19 6.2 3.4
12000 -2.0 28.4 185 28 14 6.7 3.7 | -2.9 26.8 200 36 18 6.2 3.4
11500 -1.1 30.0 185 26 13 6.6 3.6 | -2.0 28.4 200 35 18 6.0 3.3
11000 -0.1 31.8 185 24 12 6.6 3.6 | -1.1 30.0 200 34 18 6.1 3.3
10500 0.8 33.4 185 22 12 6.2 3.4 | -0.3 31.5 200 33 17 5.1 2.8
10250 1.3 34.3 185 22 11 7.6 4.2 | 0.1 32.2 200 33 17 5.6 3.1
10000 2.0 35.6 185 21 11 9.8 5.4 | 0.5 32.9 200 32 16 6.9 3.8
9750 2.7 36.9 180 20 10 9.3 5.1 | 1.0 33.8 200 31 16 7.1 3.9
9500 3.3 37.9 180 19 10 8.7 4.8 | 1.5 34.7 200 30 15 6.7 3.7
9250 4.0 39.2 180 18 9 8.9 4.9 | 2.0 35.6 200 29 15 7.1 3.9
9000 4.6 40.3 180 17 9 8.7 4.8 | 2.5 36.5 200 28 14 5.8 3.2
8750 5.3 41.5 180 16 8 8.8 4.8 | 2.9 37.2 200 26 13 5.8 3.2
8500 6.6 43.9 180 15 8 8.8 4.8 | 3.9 39.0 195 23 12 6.4 3.5
8250 7.3 45.1 180 14 7 9.9 5.4 | 4.4 39.9 195 22 11 8.7 4.7
8000 8.1 46.6 180 14 7 9.6 5.2 | 5.1 41.2 195 22 11 8.5 4.6
7750 8.7 47.7 180 13 7 8.3 4.5 | 5.6 42.1 195 20 10 6.2 3.4
7500 9.3 48.7 180 12 6 8.7 4.8 | 6.0 42.8 195 18 9 6.7 3.7
7250 10.0 50.0 180 11 6 9.0 4.9 | 6.5 43.7 195 16 8 7.7 4.2
7000 10.7 51.3 180 11 6 8.8 4.8 | 7.1 44.8 195 16 8 8.2 4.5
6750 11.3 52.3 185 10 5 8.2 4.5 | 7.7 45.9 195 14 7 7.5 4.1
6500 11.9 53.4 185 9 4 9.3 5.1 | 8.2 46.8 190 12 6 7.9 4.3
6250 12.7 54.9 185 8 4 11.8 6.5 | 8.8 47.8 190 10 5 8.7 4.8
6000 13.5 56.3 185 8 4 8.2 4.5 | 9.5 49.1 195 8 4 7.9 4.3
5750 13.9 57.0 190 7 4 5.4 3.0 | 9.9 49.8 195 7 4 4.7 2.6
5500 15.4 59.7 190 6 3 46.1 25.3 | 10.2 50.4 190 2 1 4.8 2.6
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.
042613