Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
293
UXUS97 KGJT 011306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Monday, December 1, 2025
This forecast is for Monday, December 1, 2025:
If the trigger temperature of 43.1 F/6.2 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 242 ft/min (1.2 m/s)
Maximum height of thermals.................. 8798 ft MSL (3192 ft AGL)
Forecast maximum temperature................... 40.0 F/4.9 C
Time of trigger temperature.................... None
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................. 7273 ft MSL (1666 ft AGL)
Thermal soaring outlook for Tuesday 12/02...... Fair
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:14:54 / 16:51:49 MST
Total possible sunshine........... 9 hr 36 min 55 sec (576 min 55 sec)
Altitude of sun at 12:03:22 MST... 28.95 degrees
Upper air data from rawinsonde observation taken on 12/01/2025 at 0500 MST
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 20302 ft MSL (14696 ft AGL)
Lifted condensation level....... 12535 ft MSL (6929 ft AGL)
Lifted index.................... +16.3
K index......................... +2.9
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 -62.3 -80.1 285 33 17 -0.2 -0.1 M M M M M
45000 -62.6 -80.7 280 47 24 0.1 0.1 M M M M M
40000 -61.1 -78.0 290 63 33 1.1 0.6 M M M M M
38000 -59.3 -74.7 290 66 34 5.0 2.7 M M M M M
36000 -56.3 -69.3 290 65 34 5.0 2.7 M M M M M
34000 -53.0 -63.4 295 64 33 9.0 4.9 M M M M M
32000 -47.2 -53.0 290 60 31 8.6 4.7 M M M M M
30000 -42.1 -43.8 290 57 29 8.3 4.5 33.5 92.3 21.9 M M
29000 -39.7 -39.5 290 56 29 8.2 4.5 32.8 91.1 21.6 M M
28000 -37.2 -35.0 290 54 28 8.2 4.5 32.3 90.1 21.5 M M
27000 -34.7 -30.5 290 53 27 7.8 4.3 31.9 89.4 21.4 M M
26000 -32.5 -26.5 290 52 27 7.4 4.1 30.8 87.5 20.8 M M
25000 -30.3 -22.5 285 51 26 7.4 4.1 30.0 85.9 20.4 M M
24000 -28.1 -18.6 285 50 26 7.5 4.1 29.2 84.6 20.0 M M
23000 -25.9 -14.6 285 49 25 7.5 4.1 28.3 82.9 19.4 M M
22000 -23.7 -10.7 285 47 24 7.5 4.1 27.5 81.5 18.9 M M
21000 -21.5 -6.7 290 46 24 7.3 4.0 26.8 80.2 18.5 M M
20000 -19.4 -2.9 290 43 22 7.1 3.9 25.7 78.3 17.9 M M
19500 -18.3 -0.9 290 42 22 7.1 3.9 25.3 77.5 17.6 M M
19000 -16.7 1.9 290 40 21 7.2 3.9 24.6 76.4 17.1 M M
18500 -15.7 3.7 290 39 20 6.6 3.6 24.2 75.6 16.8 M M
18000 -14.8 5.4 295 37 19 6.5 3.6 23.6 74.5 16.4 M M
17500 -13.8 7.2 295 36 18 6.4 3.5 23.1 73.5 16.0 M M
17000 -12.9 8.8 295 35 18 5.8 3.2 22.4 72.4 15.5 M M
16500 -12.1 10.2 295 33 17 5.9 3.2 21.8 71.2 14.9 M M
16000 -11.3 11.7 300 33 17 5.1 2.8 21.1 69.9 14.4 M M
15500 -10.5 13.1 300 32 16 5.1 2.8 20.3 68.5 13.7 M M
15000 -9.8 14.4 300 31 16 4.2 2.3 19.5 67.1 13.1 M M
14500 -9.3 15.3 295 31 16 3.7 2.0 18.5 65.2 12.2 M M
14000 -8.7 16.3 295 31 16 3.4 1.9 17.5 63.5 11.4 M M
13500 -8.3 17.1 290 29 15 2.9 1.6 16.4 61.5 10.4 M M
13000 -7.8 18.0 290 28 15 2.8 1.5 15.3 59.5 9.5 M M
12500 -7.4 18.7 285 26 14 2.3 1.3 14.1 57.3 8.6 M M
12000 -6.9 19.6 280 24 13 2.1 1.2 12.9 55.2 7.6 M M
11500 -6.7 19.9 275 22 11 0.5 0.3 11.5 52.7 6.4 M M
11000 -6.6 20.1 270 20 10 0.8 0.4 10.1 50.1 5.1 M M
10500 -6.4 20.5 265 18 9 1.6 0.9 8.7 47.7 3.8 M M
10250 -6.3 20.7 260 17 9 1.2 0.7 8.1 46.5 3.2 M M
10000 -6.2 20.8 255 16 8 1.9 1.1 7.4 45.3 2.6 M M
9750 -6.0 21.2 255 15 8 2.9 1.6 6.8 44.3 2.0 M M
9500 -5.8 21.6 250 14 7 3.2 1.8 6.3 43.3 1.5 M M
9250 -5.6 21.9 250 13 7 2.2 1.2 5.8 42.4 1.0 M M
9000 -5.4 22.3 245 12 6 3.0 1.6 5.2 41.3 0.4 M M
8750 -5.1 22.8 245 11 6 4.4 2.4 4.7 40.5 0.0 M M
8500 -4.8 23.4 240 10 5 4.4 2.4 4.3 39.7 -0.4 226 1.1
8250 -4.5 23.9 235 9 5 3.1 1.7 3.9 39.0 -0.8 209 1.1
8000 -4.4 24.1 225 8 4 2.4 1.3 3.3 37.9 -1.4 197 1.0
7750 -4.1 24.6 220 7 4 3.3 1.8 2.8 37.0 -1.9 183 0.9
7500 -3.9 25.0 210 7 3 2.9 1.6 2.3 36.1 -2.4 169 0.9
7250 -3.7 25.3 200 6 3 4.4 2.4 1.8 35.2 -2.9 154 0.8
7000 -3.3 26.1 185 7 4 3.9 2.1 1.4 34.6 -3.3 136 0.7
6750 -3.1 26.4 180 7 4 2.4 1.3 0.9 33.6 -3.8 123 0.6
6500 -2.9 26.8 175 7 4 1.5 0.8 0.3 32.6 -4.4 110 0.6
6250 -3.0 26.6 165 7 4 -1.8 -1.0 -0.4 31.2 -5.2 103 0.5
6000 -3.0 26.6 155 7 4 2.4 1.3 -1.2 29.8 -6.0 98 0.5
5750 -2.7 27.1 150 7 3 3.9 2.2 -1.6 29.1 -6.4 80 0.4
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 * * * * * *
12/01/2025 at 0800 MST | 12/01/2025 at 1100 MST
|
CAPE... 0.0 LI... +7.6 | CAPE... 0.0 LI... +10.4
CINH... 0.0 K Index... -7.4 | CINH... 0.0 K Index... -12.8
|
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 -58.6 -73.5 320 28 14 0.0 0.0 | -60.3 -76.5 335 30 15 -0.4 -0.2
45000 -58.6 -73.5 330 35 18 0.1 0.0 | -60.9 -77.6 340 40 21 -0.5 -0.3
40000 -56.1 -69.0 005 50 26 1.7 0.9 | -58.4 -73.1 010 64 33 1.7 1.0
38000 -54.7 -66.5 010 60 31 3.5 1.9 | -56.5 -69.7 010 73 37 5.0 2.7
36000 -52.6 -62.7 015 73 38 3.5 1.9 | -53.5 -64.3 010 77 40 5.0 2.7
34000 -50.5 -58.9 020 86 44 4.1 2.3 | -50.4 -58.7 005 81 42 5.8 3.2
32000 -47.5 -53.5 015 86 44 5.1 2.8 | -46.9 -52.4 005 75 39 6.0 3.3
30000 -44.5 -48.1 015 85 44 5.6 3.1 | -43.2 -45.8 005 69 36 6.4 3.5
29000 -42.7 -44.9 015 81 42 6.1 3.3 | -41.3 -42.3 005 67 34 6.4 3.5
28000 -40.8 -41.4 015 76 39 6.1 3.3 | -39.4 -38.9 010 64 33 6.4 3.5
27000 -39.0 -38.2 015 72 37 6.1 3.3 | -37.5 -35.5 010 62 32 6.4 3.5
26000 -37.3 -35.1 010 66 34 5.6 3.1 | -34.8 -30.6 010 59 30 7.3 4.0
25000 -35.2 -31.4 010 57 29 5.6 3.0 | -32.6 -26.7 010 57 29 7.3 4.0
24000 -33.5 -28.3 005 51 26 5.5 3.0 | -30.4 -22.7 010 55 28 7.4 4.1
23000 -31.7 -25.1 005 46 24 6.5 3.6 | -28.4 -19.1 005 52 27 6.5 3.6
22000 -29.7 -21.5 360 43 22 6.5 3.6 | -26.5 -15.7 005 48 25 6.5 3.6
21000 -27.8 -18.0 360 40 21 6.3 3.5 | -24.5 -12.1 360 45 23 6.0 3.3
20000 -26.2 -15.2 355 38 19 4.8 2.6 | -23.0 -9.4 355 41 21 5.0 2.7
19500 -25.5 -13.9 355 37 19 4.8 2.7 | -22.3 -8.1 355 39 20 5.0 2.7
19000 -24.8 -12.6 355 35 18 4.8 2.7 | -21.5 -6.7 355 38 19 5.0 2.7
18500 -24.1 -11.4 350 34 18 4.8 2.7 | -20.8 -5.4 350 36 18 4.9 2.7
18000 -23.4 -10.1 350 33 17 3.6 1.9 | -20.1 -4.2 350 35 18 4.4 2.4
17500 -22.9 -9.2 345 31 16 3.6 2.0 | -19.4 -2.9 345 34 17 4.5 2.5
17000 -22.3 -8.1 345 29 15 4.6 2.5 | -18.9 -2.0 345 33 17 2.6 1.4
16500 -21.6 -6.9 345 27 14 4.9 2.7 | -18.5 -1.3 340 32 16 2.5 1.4
16000 -20.9 -5.6 340 25 13 5.3 2.9 | -18.1 -0.6 340 30 16 2.7 1.5
15500 -20.0 -4.0 340 24 12 5.9 3.3 | -17.7 0.1 335 29 15 2.9 1.6
15000 -19.1 -2.4 340 22 11 6.1 3.3 | -17.3 0.9 335 27 14 3.2 1.8
14500 -18.1 -0.6 340 21 11 6.6 3.6 | -16.7 1.9 335 25 13 4.2 2.3
14000 -17.2 1.0 345 20 10 6.6 3.6 | -16.1 3.0 335 23 12 4.3 2.4
13500 -16.2 2.8 345 19 10 6.4 3.5 | -15.3 4.5 335 22 11 5.6 3.1
13000 -15.3 4.5 345 19 10 6.5 3.5 | -14.5 5.9 335 20 10 5.5 3.0
12500 -14.4 6.1 345 18 9 5.3 2.9 | -13.7 7.3 340 19 10 5.6 3.1
12000 -13.6 7.5 350 17 9 5.5 3.0 | -12.8 9.0 340 17 9 5.6 3.1
11500 -12.8 9.0 350 17 9 5.7 3.2 | -12.0 10.4 340 16 8 5.5 3.0
11000 -11.9 10.6 355 16 8 5.7 3.1 | -11.2 11.8 345 14 7 5.5 3.0
10500 -11.1 12.0 360 15 8 5.6 3.1 | -10.4 13.3 345 13 7 5.3 2.9
10250 -10.7 12.7 360 15 8 5.9 3.2 | -10.0 14.0 350 12 6 5.7 3.1
10000 -10.3 13.5 005 15 8 5.1 2.8 | -9.6 14.7 350 11 6 4.1 2.3
9750 -9.9 14.2 005 15 8 5.1 2.8 | -9.4 15.1 350 11 6 4.2 2.3
9500 -9.5 14.9 005 15 8 6.1 3.3 | -9.0 15.8 355 10 5 5.8 3.2
9250 -9.1 15.6 010 14 7 5.7 3.1 | -8.6 16.5 360 9 5 5.2 2.9
9000 -8.6 16.5 010 14 7 6.4 3.5 | -8.2 17.2 005 9 4 6.4 3.5
8750 -7.8 18.0 015 13 7 4.1 2.2 | -7.3 18.9 010 7 4 4.4 2.4
8500 -7.5 18.5 015 12 6 4.4 2.4 | -7.0 19.4 020 7 3 4.8 2.6
8250 -7.2 19.0 020 12 6 4.3 2.4 | -6.6 20.1 025 6 3 4.4 2.4
8000 -6.9 19.6 020 11 6 4.6 2.5 | -6.3 20.7 030 6 3 5.2 2.9
7750 -6.5 20.3 025 10 5 4.9 2.7 | -5.9 21.4 040 5 2 6.2 3.4
7500 -6.1 21.0 025 9 5 4.5 2.5 | -5.4 22.3 050 4 2 5.6 3.0
7250 -5.8 21.6 030 9 4 4.0 2.2 | -5.1 22.8 060 4 2 4.1 2.3
7000 -5.5 22.1 040 8 4 4.5 2.5 | -4.7 23.5 065 4 2 7.5 4.1
6750 -5.1 22.8 040 6 3 5.1 2.8 | -4.0 24.8 070 3 2 10.4 5.7
6500 -4.8 23.4 045 5 3 5.0 2.7 | -3.2 26.2 075 3 2 9.4 5.2
6250 -4.4 24.1 050 4 2 5.7 3.1 | -2.5 27.5 080 3 2 9.0 4.9
6000 -4.0 24.8 060 4 2 3.1 1.7 | -1.8 28.8 080 3 2 11.0 6.0
5750 -4.0 24.8 075 2 1 -1.9 -1.0 | -0.8 30.6 085 3 1 17.1 9.4
5500 -3.8 25.2 120 1 0 15.8 8.7 | 0.5 32.9 085 3 1 13.8 7.5
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
12/01/2025 at 1400 MST | 12/01/2025 at 1700 MST
|
CAPE... 0.0 LI... +12.3 | CAPE... 0.0 LI... +13.0
CINH... 0.0 K Index... -10.1 | CINH... 0.0 K Index... -7.4
|
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 -61.9 -79.4 330 27 14 -1.3 -0.7 | -63.0 -81.4 315 28 15 -1.0 -0.5
45000 -64.0 -83.2 345 39 20 0.4 0.2 | -64.5 -84.1 325 36 19 0.3 0.2
40000 -58.5 -73.3 360 63 32 3.7 2.0 | -58.8 -73.8 335 59 30 3.9 2.2
38000 -55.8 -68.4 360 70 36 5.3 2.9 | -56.3 -69.3 340 66 34 4.3 2.4
36000 -52.6 -62.7 360 74 38 5.3 2.9 | -53.7 -64.7 345 70 36 4.3 2.4
34000 -49.4 -56.9 360 76 39 5.4 3.0 | -50.6 -59.1 345 72 37 5.7 3.1
32000 -46.2 -51.2 360 68 35 5.4 2.9 | -47.2 -53.0 350 62 32 5.7 3.1
30000 -42.9 -45.2 360 60 31 7.1 3.9 | -43.5 -46.3 355 53 27 8.2 4.5
29000 -40.8 -41.4 360 57 29 6.8 3.8 | -41.0 -41.8 360 50 26 8.2 4.5
28000 -38.7 -37.7 360 54 28 6.8 3.8 | -38.6 -37.5 360 47 24 8.2 4.5
27000 -36.2 -33.2 360 51 26 7.2 4.0 | -36.1 -33.0 005 44 23 8.2 4.5
26000 -33.9 -29.0 360 50 26 7.7 4.2 | -33.7 -28.7 005 43 22 8.1 4.5
25000 -31.6 -24.9 360 48 25 7.7 4.2 | -31.2 -24.2 010 42 22 8.1 4.5
24000 -29.3 -20.7 360 47 24 7.6 4.2 | -28.8 -19.8 010 41 21 8.1 4.5
23000 -27.1 -16.8 360 46 23 7.1 3.9 | -26.4 -15.5 010 41 21 8.1 4.5
22000 -25.0 -13.0 355 44 23 7.1 3.9 | -23.3 -9.9 005 40 20 8.2 4.5
21000 -22.9 -9.2 355 43 22 6.5 3.6 | -21.0 -5.8 360 39 20 6.0 3.3
20000 -21.1 -6.0 355 41 21 6.0 3.3 | -19.3 -2.7 360 37 19 5.9 3.2
19500 -20.2 -4.4 355 40 20 6.0 3.3 | -18.4 -1.1 360 36 18 5.9 3.2
19000 -19.3 -2.7 350 38 20 5.9 3.2 | -17.6 0.3 360 35 18 5.9 3.2
18500 -18.4 -1.1 350 37 19 5.2 2.9 | -16.7 1.9 360 34 17 5.8 3.2
18000 -17.8 -0.0 350 36 18 3.6 2.0 | -15.8 3.6 355 32 17 5.7 3.1
17500 -17.3 0.9 345 34 18 3.7 2.0 | -15.0 5.0 355 31 16 5.7 3.1
17000 -16.7 1.9 345 33 17 3.5 1.9 | -14.3 6.3 350 30 15 4.4 2.4
16500 -16.2 2.8 345 32 16 3.5 1.9 | -13.6 7.5 350 29 15 4.5 2.5
16000 -15.7 3.7 340 31 16 2.7 1.5 | -13.0 8.6 345 28 14 3.3 1.8
15500 -15.4 4.3 340 30 15 2.2 1.2 | -12.6 9.3 345 27 14 3.1 1.7
15000 -15.0 5.0 335 29 15 2.3 1.2 | -12.1 10.2 340 26 14 2.7 1.5
14500 -14.6 5.7 335 27 14 2.4 1.3 | -11.7 10.9 340 25 13 2.4 1.3
14000 -14.3 6.3 330 25 13 2.5 1.4 | -11.4 11.5 340 24 13 2.1 1.2
13500 -13.8 7.2 330 23 12 3.4 1.9 | -11.1 12.0 335 23 12 1.3 0.7
13000 -13.3 8.1 325 21 11 3.4 1.9 | -10.9 12.4 330 21 11 1.4 0.7
12500 -12.7 9.1 325 19 10 4.8 2.6 | -10.7 12.7 330 19 10 1.8 1.0
12000 -12.0 10.4 325 17 9 4.7 2.6 | -10.4 13.3 325 17 9 2.0 1.1
11500 -11.3 11.7 325 15 8 5.3 2.9 | -10.0 14.0 320 14 7 3.5 1.9
11000 -10.5 13.1 325 13 7 5.3 2.9 | -9.5 14.9 310 12 6 3.7 2.0
10500 -9.7 14.5 325 12 6 5.5 3.0 | -8.9 16.0 305 11 5 4.9 2.7
10250 -9.3 15.3 325 11 5 5.6 3.1 | -8.5 16.7 305 10 5 4.9 2.7
10000 -8.9 16.0 330 10 5 5.1 2.8 | -8.1 17.4 300 9 4 4.9 2.7
9750 -8.5 16.7 330 9 5 5.6 3.1 | -7.8 18.0 300 8 4 5.8 3.2
9500 -8.1 17.4 330 8 4 6.6 3.6 | -7.3 18.9 295 7 4 6.5 3.6
9250 -7.6 18.3 330 6 3 6.3 3.4 | -6.9 19.6 290 6 3 6.2 3.4
9000 -6.6 20.1 335 4 2 6.7 3.7 | -6.4 20.5 285 5 3 7.6 4.2
8750 -6.2 20.8 340 3 2 6.0 3.3 | -5.8 21.6 280 5 3 7.4 4.1
8500 -5.7 21.7 345 3 1 6.1 3.3 | -5.3 22.5 275 4 2 6.2 3.4
8250 -5.3 22.5 345 2 1 5.0 2.7 | -4.3 24.3 260 3 2 6.9 3.8
8000 -4.9 23.2 350 1 1 7.0 3.9 | -3.8 25.2 255 3 2 6.8 3.7
7750 -4.3 24.3 355 1 0 9.3 5.1 | -3.3 26.1 245 3 1 6.6 3.6
7500 -3.6 25.5 355 1 0 7.5 4.1 | -2.9 26.8 235 2 1 6.5 3.6
7250 -3.2 26.2 000 0 0 5.4 2.9 | -2.4 27.7 225 2 1 6.4 3.5
7000 -2.7 27.1 000 0 0 9.5 5.2 | -1.9 28.6 215 2 1 6.4 3.5
6750 -1.8 28.8 000 0 0 11.9 6.5 | -1.4 29.5 200 2 1 7.6 4.1
6500 -1.0 30.2 000 0 0 9.5 5.2 | -0.8 30.6 190 2 1 8.2 4.5
6250 -0.3 31.5 000 0 0 9.4 5.2 | -0.2 31.6 180 2 1 9.7 5.3
6000 0.4 32.7 000 0 0 10.6 5.8 | 0.5 32.9 175 2 1 4.3 2.4
5750 1.4 34.5 000 0 0 15.3 8.4 | 0.3 32.5 180 1 1 -9.1 -5.0
5500 2.6 36.7 000 0 0 17.5 9.6 | -0.0 32.0 180 1 1 12.2 6.7
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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