Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
212
UXUS97 KGJT 141306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Tuesday, January 14, 2025
This forecast is for Tuesday, January 14, 2025:
If the trigger temperature of 34.4 F/1.4 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 361 ft/min (1.8 m/s)
Maximum height of thermals.................. 9992 ft MSL (5153 ft AGL)
Forecast maximum temperature................... 37.0 F/3.2 C
Time of trigger temperature.................... 1330 MST
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................. 7186 ft MSL (2346 ft AGL)
Thermal soaring outlook for Wednesday 01/15.... Fair
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:31:54 / 17:14:51 MST
Total possible sunshine........... 9 hr 42 min 57 sec (582 min 57 sec)
Altitude of sun at 12:23:23 MST... 29.48 degrees
Upper air data from rawinsonde observation taken on 01/14/2025 at 0500 MST
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 16929 ft MSL (12090 ft AGL)
Lifted condensation level....... 12068 ft MSL (7229 ft AGL)
Lifted index.................... +15.2
K index......................... -8.7
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 -52.4 -62.3 345 9 5 3.3 1.8 116.3 241.4 64.4 M M
45000 -52.1 -61.8 325 27 14 -0.0 -0.0 91.9 197.4 54.0 M M
40000 -50.2 -58.4 315 21 11 -1.4 -0.8 71.5 160.6 44.4 M M
38000 -49.1 -56.4 335 44 23 -6.6 -3.6 63.0 145.4 40.1 M M
36000 -53.6 -64.5 355 28 14 -1.2 -0.6 47.7 117.9 30.8 M M
34000 -50.3 -58.5 345 24 12 5.5 3.0 44.0 111.3 29.0 M M
32000 -50.4 -58.7 355 28 14 -5.2 -2.8 35.7 96.2 23.7 M M
30000 -48.3 -54.9 355 31 16 -1.1 -0.6 30.5 86.9 20.5 M M
29000 -46.6 -51.9 360 40 21 1.6 0.9 28.8 83.9 19.5 M M
28000 -45.3 -49.5 360 40 21 8.4 4.6 26.7 80.0 18.1 M M
27000 -42.6 -44.7 005 46 24 9.0 4.9 26.4 79.6 18.2 M M
26000 -39.9 -39.8 005 53 27 9.0 4.9 26.1 79.0 18.2 M M
25000 -37.3 -35.1 005 52 27 8.4 4.6 25.7 78.3 18.1 M M
24000 -34.5 -30.1 005 54 28 9.8 5.4 25.6 78.1 18.2 M M
23000 -31.9 -25.4 005 53 27 8.6 4.7 25.2 77.3 18.1 M M
22000 -29.6 -21.3 010 61 31 5.5 3.0 24.3 75.7 17.6 M M
21000 -27.7 -17.9 010 60 31 6.1 3.4 23.0 73.5 16.8 M M
20000 -24.9 -12.8 020 55 28 7.5 4.1 22.0 71.6 16.2 M M
19500 -23.8 -10.8 020 47 24 7.2 4.0 21.6 70.9 15.9 M M
19000 -22.8 -9.0 015 40 21 6.7 3.7 21.1 70.0 15.6 M M
18500 -21.8 -7.2 015 38 19 4.9 2.7 20.6 69.0 15.2 M M
18000 -21.3 -6.3 015 34 18 0.7 0.4 19.4 66.9 14.2 M M
17500 -21.9 -7.4 020 35 18 0.9 0.5 17.1 62.8 12.3 M M
17000 -21.0 -5.8 025 36 19 5.6 3.1 16.4 61.6 11.8 M M
16500 -20.1 -4.2 020 37 19 5.8 3.2 15.8 60.4 11.3 M M
16000 -19.1 -2.4 020 35 18 7.3 4.0 15.3 59.5 10.9 M M
15500 -18.0 -0.4 020 32 17 7.1 3.9 14.8 58.7 10.6 M M
15000 -17.0 1.4 020 36 18 6.8 3.7 14.4 57.9 10.2 M M
14500 -15.9 3.4 020 33 17 2.8 1.5 13.9 57.1 9.9 M M
14000 -16.5 2.3 010 15 8 -7.0 -3.8 11.5 52.7 7.8 M M
13500 -16.7 1.9 005 15 8 -0.5 -0.3 9.7 49.5 6.2 M M
13000 -17.5 0.5 345 11 6 -0.0 -0.0 7.3 45.1 4.0 M M
12500 -17.0 1.4 325 7 4 3.3 1.8 6.3 43.3 3.1 M M
12000 -16.5 2.3 315 10 5 3.7 2.0 5.3 41.5 2.1 M M
11500 -15.8 3.6 305 9 5 5.3 2.9 4.4 40.0 1.4 M M
11000 -15.0 5.0 305 7 4 5.3 2.9 3.7 38.7 0.7 M M
10500 -14.2 6.4 285 7 4 8.5 4.7 3.0 37.4 0.0 M M
10250 -13.4 7.9 295 5 3 10.7 5.9 3.1 37.6 0.1 M M
10000 -12.7 9.1 335 4 2 6.9 3.8 3.0 37.4 0.0 M M
9750 -12.3 9.9 340 4 2 5.2 2.9 2.7 36.9 -0.3 343 1.7
9500 -11.9 10.6 345 4 2 5.2 2.9 2.3 36.2 -0.6 324 1.6
9250 -11.5 11.3 020 3 2 6.0 3.3 2.0 35.6 -0.9 305 1.5
9000 -11.0 12.2 060 3 2 6.7 3.7 1.8 35.2 -1.2 282 1.4
8750 -10.5 13.1 065 3 1 6.5 3.6 1.5 34.7 -1.4 260 1.3
8500 -10.0 14.0 060 2 1 6.6 3.6 1.3 34.3 -1.7 238 1.2
8250 -9.5 14.9 070 3 1 6.6 3.6 1.0 33.9 -1.9 216 1.1
8000 -9.1 15.6 065 4 2 6.6 3.6 0.8 33.4 -2.1 194 1.0
7750 -8.6 16.5 060 4 2 6.6 3.6 0.5 33.0 -2.4 172 0.9
7500 -8.1 17.4 055 4 2 6.6 3.6 0.3 32.5 -2.6 149 0.8
7250 -7.6 18.3 050 3 1 6.6 3.6 0.1 32.1 -2.9 127 0.6
7000 -7.1 19.2 345 1 1 6.6 3.6 -0.2 31.6 -3.1 105 0.5
6750 -6.6 20.1 085 1 1 6.6 3.6 -0.4 31.2 -3.4 83 0.4
6500 -6.1 21.0 130 3 1 6.5 3.6 -0.7 30.7 -3.6 61 0.3
6250 -5.6 21.9 140 4 2 7.0 3.8 -1.0 30.3 -3.9 39 0.2
6000 -5.1 22.8 145 6 3 5.2 2.8 -1.2 29.9 -4.2 16 0.1
5750 -4.8 23.4 155 7 4 4.3 2.3 -1.6 29.1 -4.6 M M
5500 -4.5 23.9 180 6 3 2.0 1.1 -2.1 28.3 -5.0 M M
5250 -4.5 23.9 200 5 3 0.2 0.1 -2.8 27.0 -5.8 M M
5000 -4.4 24.1 195 4 2 2.7 1.5 -3.4 25.9 -6.4 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
01/14/2025 at 0800 MST | 01/14/2025 at 1100 MST
|
CAPE... 0.0 LI... +8.9 | CAPE... 0.0 LI... +4.5
CINH... -0.0 K Index... -3.0 | CINH... -0.1 K Index... +4.9
|
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 -52.5 -62.5 320 14 7 1.3 0.7 | -52.4 -62.3 345 16 8 1.8 1.0
45000 -50.5 -58.9 305 19 10 1.5 0.8 | -49.8 -57.6 335 19 10 1.8 1.0
40000 -49.9 -57.8 335 30 15 0.3 0.2 | -48.0 -54.4 350 22 11 1.1 0.6
38000 -49.7 -57.5 335 33 17 0.2 0.1 | -47.6 -53.7 355 23 12 -0.3 -0.2
36000 -49.6 -57.3 330 29 15 0.2 0.1 | -47.8 -54.0 350 24 12 -0.3 -0.2
34000 -49.5 -57.1 325 26 13 0.3 0.2 | -47.9 -54.2 350 25 13 -0.2 -0.1
32000 -48.9 -56.0 345 36 18 1.0 0.6 | -47.2 -53.0 360 33 17 1.4 0.8
30000 -48.3 -54.9 360 50 26 1.7 0.9 | -46.4 -51.5 010 42 22 1.5 0.8
29000 -47.0 -52.6 355 52 27 4.7 2.6 | -45.3 -49.5 010 45 23 4.3 2.3
28000 -45.6 -50.1 350 54 28 4.7 2.6 | -44.0 -47.2 010 46 24 4.2 2.3
27000 -44.2 -47.6 350 56 29 4.8 2.6 | -42.7 -44.9 010 48 25 4.3 2.3
26000 -42.5 -44.5 345 57 30 7.2 3.9 | -41.2 -42.2 010 49 25 6.0 3.3
25000 -40.3 -40.5 345 58 30 7.2 4.0 | -39.0 -38.2 010 48 25 5.9 3.2
24000 -38.1 -36.6 345 59 30 7.2 4.0 | -37.2 -35.0 005 47 24 6.0 3.3
23000 -35.3 -31.5 345 59 30 8.1 4.4 | -35.8 -32.4 005 46 24 3.9 2.2
22000 -32.9 -27.2 345 59 30 8.1 4.4 | -34.7 -30.5 360 44 23 3.9 2.1
21000 -30.5 -22.9 345 59 30 7.7 4.2 | -33.5 -28.3 355 42 22 4.2 2.3
20000 -28.4 -19.1 350 54 28 6.8 3.7 | -31.8 -25.2 355 40 20 6.2 3.4
19500 -27.4 -17.3 350 51 26 6.8 3.7 | -30.8 -23.4 355 38 20 6.2 3.4
19000 -26.4 -15.5 350 48 25 6.8 3.7 | -29.9 -21.8 355 37 19 6.2 3.4
18500 -25.3 -13.5 355 46 24 6.6 3.6 | -29.0 -20.2 355 36 18 6.3 3.5
18000 -24.4 -11.9 355 43 22 6.0 3.3 | -28.0 -18.4 355 35 18 7.2 3.9
17500 -23.5 -10.3 355 41 21 6.1 3.3 | -26.9 -16.4 355 34 18 7.1 3.9
17000 -22.6 -8.7 360 39 20 5.6 3.1 | -25.8 -14.4 350 34 17 8.0 4.4
16500 -21.8 -7.2 360 38 20 5.6 3.1 | -24.6 -12.3 350 33 17 8.0 4.4
16000 -21.0 -5.8 005 38 19 5.1 2.8 | -23.5 -10.3 350 32 17 7.3 4.0
15500 -20.3 -4.5 005 37 19 4.9 2.7 | -22.5 -8.5 350 31 16 7.0 3.8
15000 -19.6 -3.3 010 37 19 5.2 2.9 | -21.4 -6.5 350 29 15 7.4 4.1
14500 -18.7 -1.7 015 37 19 5.6 3.1 | -20.3 -4.5 355 27 14 7.9 4.3
14000 -17.9 -0.2 020 36 18 5.3 2.9 | -19.1 -2.4 355 26 13 7.6 4.2
13500 -17.2 1.0 020 34 18 4.3 2.4 | -18.0 -0.4 005 24 12 6.8 3.7
13000 -16.6 2.1 025 32 17 4.2 2.3 | -17.0 1.4 010 23 12 6.5 3.5
12500 -16.0 3.2 025 28 15 3.5 1.9 | -16.1 3.0 015 21 11 5.4 3.0
12000 -15.5 4.1 025 24 12 3.7 2.0 | -15.3 4.5 015 18 9 5.3 2.9
11500 -14.9 5.2 025 19 10 4.2 2.3 | -14.6 5.7 015 16 8 5.0 2.7
11000 -14.3 6.3 015 16 8 3.8 2.1 | -13.8 7.2 015 13 7 5.0 2.8
10500 -13.8 7.2 010 13 7 3.2 1.8 | -13.1 8.4 010 11 6 5.1 2.8
10250 -13.6 7.5 005 11 6 3.2 1.8 | -12.7 9.1 005 10 5 5.1 2.8
10000 -13.3 8.1 360 10 5 3.6 2.0 | -12.3 9.9 005 9 5 4.4 2.4
9750 -13.0 8.6 360 9 5 4.7 2.6 | -12.0 10.4 005 8 4 3.8 2.1
9500 -12.6 9.3 355 8 4 5.1 2.8 | -11.7 10.9 360 7 4 3.6 2.0
9250 -12.3 9.9 355 7 4 5.4 3.0 | -11.5 11.3 360 6 3 4.3 2.4
9000 -11.8 10.8 355 6 3 6.8 3.8 | -11.1 12.0 360 5 3 6.0 3.3
8750 -11.3 11.7 355 5 3 6.4 3.5 | -10.3 13.5 010 3 2 3.6 2.0
8500 -10.5 13.1 005 4 2 6.0 3.3 | -10.0 14.0 020 3 2 5.1 2.8
8250 -10.0 14.0 015 4 2 6.9 3.8 | -9.6 14.7 035 3 1 6.5 3.6
8000 -9.5 14.9 020 3 2 6.3 3.4 | -9.1 15.6 050 3 1 5.5 3.0
7750 -9.1 15.6 040 3 2 5.9 3.3 | -8.7 16.3 070 3 1 5.2 2.9
7500 -8.6 16.5 050 3 2 5.9 3.2 | -8.3 17.1 075 3 1 6.1 3.3
7250 -8.2 17.2 060 4 2 6.7 3.7 | -7.9 17.8 085 3 1 5.5 3.0
7000 -7.7 18.1 065 4 2 4.0 2.2 | -7.4 18.7 090 3 2 7.6 4.2
6750 -7.5 18.5 080 3 2 2.9 1.6 | -6.8 19.8 095 3 2 8.5 4.7
6500 -7.2 19.0 085 3 2 4.4 2.4 | -6.2 20.8 105 3 1 7.2 4.0
6250 -6.9 19.6 090 3 2 5.0 2.8 | -5.7 21.7 110 3 1 7.4 4.0
6000 -6.6 20.1 090 4 2 -0.6 -0.3 | -5.0 23.0 110 3 1 11.3 6.2
5750 -7.2 19.0 090 3 2 -14.0 -7.7 | -3.9 25.0 110 3 1 18.7 10.3
5500 -7.8 18.0 095 2 1 7.3 4.0 | -2.7 27.1 110 3 1 6.5 3.6
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
01/14/2025 at 1400 MST | 01/14/2025 at 1700 MST
|
CAPE... 0.0 LI... +4.0 | CAPE... 0.0 LI... +6.6
CINH... 0.0 K Index... +6.4 | CINH... -0.3 K Index... -1.8
|
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 -53.0 -63.4 360 15 8 1.7 0.9 | -53.8 -64.8 010 14 7 1.8 1.0
45000 -50.4 -58.7 005 17 9 1.7 0.9 | -51.1 -60.0 010 19 10 1.7 1.0
40000 -47.9 -54.2 360 23 12 1.6 0.9 | -50.3 -58.5 015 25 13 0.5 0.3
38000 -47.4 -53.3 360 25 13 -0.7 -0.4 | -50.2 -58.4 020 28 14 -0.2 -0.1
36000 -47.8 -54.0 005 27 14 -0.7 -0.4 | -50.3 -58.5 030 33 17 -0.2 -0.1
34000 -48.2 -54.8 005 29 15 -0.4 -0.2 | -50.4 -58.7 035 39 20 1.1 0.6
32000 -47.8 -54.0 010 32 17 0.9 0.5 | -48.7 -55.7 040 44 23 2.9 1.6
30000 -47.2 -53.0 015 35 18 1.7 0.9 | -46.9 -52.4 040 49 25 5.1 2.8
29000 -45.8 -50.4 015 37 19 5.5 3.0 | -44.8 -48.6 040 47 24 7.2 3.9
28000 -44.1 -47.4 015 38 19 5.5 3.0 | -42.6 -44.7 035 45 23 7.2 4.0
27000 -42.5 -44.5 020 39 20 5.5 3.0 | -40.4 -40.7 035 43 22 7.2 4.0
26000 -40.7 -41.3 015 41 21 6.3 3.5 | -38.4 -37.1 035 40 21 6.8 3.7
25000 -38.3 -36.9 015 44 23 6.3 3.5 | -35.8 -32.4 035 36 18 6.8 3.7
24000 -36.5 -33.7 015 47 24 6.3 3.4 | -33.8 -28.8 035 32 17 6.9 3.8
23000 -34.5 -30.1 015 49 25 6.7 3.7 | -32.0 -25.6 030 30 16 5.7 3.1
22000 -32.5 -26.5 015 49 25 6.7 3.7 | -30.3 -22.5 030 29 15 5.7 3.1
21000 -30.5 -22.9 010 50 26 5.9 3.3 | -28.6 -19.5 025 28 14 5.2 2.8
20000 -29.5 -21.1 010 44 23 3.0 1.6 | -27.3 -17.1 025 29 15 4.2 2.3
19500 -29.1 -20.4 010 40 21 3.0 1.6 | -26.7 -16.1 020 29 15 4.2 2.3
19000 -28.6 -19.5 010 37 19 3.0 1.7 | -26.1 -15.0 020 30 15 4.2 2.3
18500 -28.2 -18.8 010 33 17 3.4 1.9 | -25.4 -13.7 015 31 16 4.3 2.4
18000 -27.5 -17.5 010 30 15 5.4 3.0 | -24.7 -12.5 015 30 16 4.7 2.6
17500 -26.7 -16.1 010 27 14 5.2 2.9 | -24.0 -11.2 015 30 15 4.9 2.7
17000 -25.8 -14.4 005 25 13 6.6 3.6 | -23.5 -10.3 010 28 15 2.6 1.4
16500 -24.9 -12.8 360 23 12 6.6 3.6 | -23.1 -9.6 010 26 13 2.7 1.5
16000 -23.9 -11.0 360 22 12 7.2 3.9 | -22.6 -8.7 010 23 12 4.8 2.7
15500 -22.8 -9.0 355 22 11 7.4 4.1 | -21.8 -7.2 005 21 11 5.5 3.0
15000 -21.7 -7.1 350 22 11 7.6 4.2 | -20.9 -5.6 360 19 10 6.2 3.4
14500 -20.5 -4.9 350 21 11 7.8 4.3 | -19.9 -3.8 360 18 9 6.8 3.7
14000 -19.4 -2.9 350 20 10 7.6 4.2 | -18.9 -2.0 355 17 9 7.0 3.8
13500 -18.3 -0.9 355 19 10 7.2 3.9 | -17.9 -0.2 355 15 8 7.3 4.0
13000 -17.2 1.0 355 18 9 7.2 4.0 | -16.8 1.8 355 14 7 7.2 4.0
12500 -16.1 3.0 355 18 9 7.3 4.0 | -15.8 3.6 350 14 7 7.1 3.9
12000 -15.1 4.8 350 17 9 7.2 3.9 | -14.7 5.5 350 13 7 7.0 3.8
11500 -14.0 6.8 355 16 8 7.0 3.8 | -13.7 7.3 350 12 6 6.8 3.7
11000 -13.0 8.6 355 14 7 6.6 3.6 | -12.7 9.1 350 11 6 6.6 3.6
10500 -12.0 10.4 355 11 6 6.1 3.4 | -11.7 10.9 350 10 5 6.5 3.5
10250 -11.6 11.1 355 10 5 6.1 3.3 | -11.2 11.8 355 9 5 6.4 3.5
10000 -11.2 11.8 355 9 5 4.9 2.7 | -10.8 12.6 355 9 5 5.7 3.1
9750 -10.8 12.6 355 8 4 4.3 2.4 | -10.4 13.3 355 8 4 5.8 3.2
9500 -10.5 13.1 360 7 4 4.7 2.6 | -9.9 14.2 355 7 4 6.3 3.5
9250 -10.1 13.8 360 6 3 4.8 2.7 | -9.5 14.9 360 7 3 6.2 3.4
9000 -9.3 15.3 015 5 2 4.7 2.6 | -9.0 15.8 005 6 3 6.7 3.7
8750 -9.0 15.8 025 4 2 2.8 1.5 | -8.1 17.4 015 5 2 4.6 2.5
8500 -8.8 16.2 035 4 2 4.7 2.6 | -7.8 18.0 025 4 2 5.4 3.0
8250 -8.4 16.9 040 4 2 5.8 3.2 | -7.3 18.9 035 4 2 6.2 3.4
8000 -7.9 17.8 050 4 2 5.9 3.3 | -6.9 19.6 045 4 2 4.9 2.7
7750 -7.5 18.5 060 4 2 6.6 3.6 | -6.5 20.3 055 4 2 5.1 2.8
7500 -7.0 19.4 065 4 2 6.8 3.7 | -6.1 21.0 060 4 2 6.7 3.7
7250 -6.5 20.3 065 4 2 6.0 3.3 | -5.6 21.9 070 4 2 6.7 3.7
7000 -6.0 21.2 070 4 2 9.0 4.9 | -5.1 22.8 075 4 2 6.8 3.7
6750 -5.2 22.6 070 3 2 9.9 5.4 | -4.6 23.7 080 3 1 7.3 4.0
6500 -4.6 23.7 070 3 2 7.7 4.2 | -4.0 24.8 085 3 1 7.1 3.9
6250 -4.0 24.8 075 3 1 7.8 4.3 | -3.5 25.7 090 3 1 8.2 4.5
6000 -3.3 26.1 075 3 1 10.9 6.0 | -2.9 26.8 100 3 2 7.0 3.8
5750 -2.2 28.0 080 3 2 18.2 10.0 | -2.5 27.5 105 3 1 1.1 0.6
5500 -1.1 30.0 080 3 1 5.9 3.2 | -2.3 27.9 110 2 1 10.5 5.8
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
________________________________________________________________________________
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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