Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
188
UXUS97 KGJT 041306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Tuesday, February 4, 2025
This forecast is for Tuesday, February 4, 2025:
If the trigger temperature of 69.9 F/21.1 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 6342 ft MSL (1519 ft AGL)
Forecast maximum temperature................... 66.0 F/19.3 C
Time of trigger temperature.................... None
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................. 5957 ft MSL (1134 ft AGL)
Thermal soaring outlook for Wednesday 02/05.... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:17:22 / 17:38:50 MST
Total possible sunshine........... 10 hr 21 min 29 sec (621 min 29 sec)
Altitude of sun at 12:28:06 MST... 34.52 degrees
Upper air data from rawinsonde observation taken on 02/04/2025 at 0500 MST
Freezing level.................. 12411 ft MSL (7588 ft AGL)
Convective condensation level... 18566 ft MSL (13743 ft AGL)
Lifted condensation level....... 15659 ft MSL (10836 ft AGL)
Lifted index.................... +6.9
K index......................... +2.8
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 -62.9 -81.2 270 42 22 5.9 3.3 94.2 201.6 43.1 M M
45000 -54.7 -66.5 280 64 33 5.2 2.9 82.2 179.9 38.9 M M
40000 -52.2 -62.0 255 85 44 2.8 1.5 63.3 145.9 29.1 M M
38000 -51.5 -60.7 245 88 45 0.4 0.2 55.5 131.8 24.7 M M
36000 -56.2 -69.2 240 84 43 10.1 5.6 39.9 103.9 14.6 M M
34000 -51.6 -60.9 240 76 39 6.4 3.5 38.2 100.7 13.7 M M
32000 -46.8 -52.2 250 66 34 10.4 5.7 36.8 98.3 13.1 M M
30000 -40.4 -40.7 250 61 31 8.7 4.8 36.5 97.8 13.2 M M
29000 -37.8 -36.0 245 60 31 8.6 4.7 36.1 97.0 13.1 M M
28000 -35.2 -31.4 245 61 31 8.8 4.8 35.7 96.2 12.9 M M
27000 -32.6 -26.7 250 63 32 8.8 4.8 35.3 95.6 12.7 M M
26000 -30.3 -22.5 245 62 32 5.9 3.3 34.6 94.2 12.3 M M
25000 -28.1 -18.6 240 58 30 8.1 4.5 33.7 92.6 11.7 M M
24000 -26.0 -14.8 240 58 30 7.7 4.2 32.6 90.8 11.0 M M
23000 -23.3 -9.9 240 56 29 7.6 4.2 32.3 90.2 10.9 M M
22000 -21.0 -5.8 240 48 25 5.8 3.2 31.5 88.8 10.4 M M
21000 -19.3 -2.7 240 48 25 5.9 3.2 30.1 86.2 9.3 M M
20000 -17.6 0.3 235 50 26 5.8 3.2 28.7 83.7 8.2 M M
19500 -16.8 1.8 235 50 26 5.7 3.1 28.0 82.4 7.6 M M
19000 -15.9 3.4 230 47 24 6.8 3.7 27.4 81.2 7.0 M M
18500 -14.7 5.5 230 46 24 8.3 4.6 27.0 80.6 6.8 M M
18000 -13.5 7.7 230 48 25 7.7 4.2 26.7 80.1 6.6 M M
17500 -12.3 9.9 230 47 24 7.6 4.1 26.4 79.5 6.4 M M
17000 -11.2 11.8 230 47 24 6.9 3.8 25.9 78.7 6.1 M M
16500 -10.1 13.8 225 45 23 8.3 4.6 25.6 78.0 5.8 M M
16000 -8.3 17.1 235 42 22 7.8 4.3 25.2 77.3 5.4 M M
15500 -7.2 19.0 235 41 21 7.2 3.9 24.8 76.6 5.1 M M
15000 -6.1 21.0 235 39 20 7.3 4.0 24.4 75.8 4.8 M M
14500 -5.0 23.0 235 38 20 7.5 4.1 23.9 75.1 4.4 M M
14000 -4.0 24.8 240 37 19 8.1 4.5 23.6 74.4 4.0 M M
13500 -2.7 27.1 240 37 19 9.1 5.0 23.4 74.2 3.8 M M
13000 -1.4 29.5 245 34 18 8.6 4.7 23.3 73.9 3.7 M M
12500 -0.1 31.8 240 32 17 8.6 4.7 23.1 73.6 3.6 M M
12000 1.2 34.2 235 31 16 8.7 4.7 23.0 73.3 3.4 M M
11500 2.5 36.5 235 31 16 8.7 4.7 22.8 73.0 3.3 M M
11000 3.8 38.8 230 28 14 8.7 4.7 22.6 72.7 3.1 M M
10500 5.1 41.2 225 28 15 8.7 4.8 22.4 72.3 3.0 M M
10250 5.7 42.3 220 29 15 8.4 4.6 22.3 72.2 2.9 M M
10000 6.3 43.3 220 29 15 7.8 4.3 22.2 72.0 2.8 M M
9750 6.9 44.4 215 28 14 7.7 4.2 22.0 71.7 2.6 M M
9500 7.5 45.5 210 27 14 7.7 4.2 21.9 71.4 2.5 M M
9250 8.1 46.6 205 27 14 7.7 4.2 21.7 71.1 2.3 M M
9000 8.6 47.5 205 26 13 7.7 4.2 21.6 70.9 2.2 M M
8750 9.2 48.6 205 26 13 7.7 4.2 21.4 70.6 2.1 M M
8500 9.8 49.6 205 25 13 7.7 4.2 21.3 70.3 1.9 M M
8250 10.4 50.7 205 24 12 7.7 4.2 21.1 70.0 1.8 M M
8000 10.9 51.6 195 24 12 7.7 4.2 21.0 69.8 1.6 M M
7750 11.5 52.7 195 24 12 7.7 4.2 20.8 69.5 1.5 M M
7500 12.1 53.8 190 23 12 7.8 4.3 20.6 69.2 1.3 M M
7250 12.7 54.9 190 22 11 7.6 4.2 20.5 68.9 1.1 M M
7000 13.2 55.8 185 21 11 8.3 4.6 20.3 68.6 1.0 M M
6750 13.8 56.8 185 21 11 5.3 2.9 20.2 68.3 0.8 M M
6500 14.1 57.4 180 20 10 6.0 3.3 19.7 67.5 0.4 M M
6250 14.3 57.7 170 17 9 -7.3 -4.0 19.2 66.6 -0.1 30 0.2
6000 13.0 55.4 160 14 7 -20.5 -11.3 17.1 62.9 -2.2 64 0.3
5750 11.6 52.9 160 12 6 -17.0 -9.3 15.1 59.1 -4.3 97 0.5
5500 10.3 50.5 145 5 3 -17.9 -9.8 13.0 55.4 -6.4 130 0.7
5250 8.9 48.0 105 7 4 -17.6 -9.6 10.9 51.7 -8.5 164 0.8
5000 7.6 45.7 110 10 5 -17.9 -9.8 8.9 48.0 -10.6 197 1.0
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
02/04/2025 at 0800 MST | 02/04/2025 at 1100 MST
|
CAPE... 0.0 LI... +1.9 | CAPE... 0.0 LI... +1.8
CINH... 0.0 K Index... +15.9 | CINH... -0.2 K Index... +18.4
|
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 -62.5 -80.5 265 56 29 4.0 2.2 | -62.4 -80.3 265 59 31 4.0 2.2
45000 -56.4 -69.5 265 73 37 4.9 2.7 | -56.2 -69.2 265 74 38 5.3 2.9
40000 -48.7 -55.7 265 78 40 4.6 2.5 | -47.9 -54.2 260 79 41 5.0 2.8
38000 -49.6 -57.3 255 77 40 -3.6 -2.0 | -48.4 -55.1 255 78 40 -3.1 -1.7
36000 -51.7 -61.1 245 77 40 -3.6 -2.0 | -50.2 -58.4 245 79 41 -3.1 -1.7
34000 -51.7 -61.1 240 77 40 7.6 4.2 | -50.5 -58.9 235 80 41 5.9 3.2
32000 -47.0 -52.6 240 74 38 7.8 4.3 | -46.8 -52.2 235 79 41 6.1 3.3
30000 -42.1 -43.8 240 72 37 9.0 4.9 | -42.6 -44.7 230 78 40 8.9 4.9
29000 -39.5 -39.1 240 72 37 9.0 4.9 | -39.9 -39.8 230 76 39 9.0 4.9
28000 -36.8 -34.2 235 72 37 9.0 4.9 | -37.2 -35.0 230 75 39 9.0 4.9
27000 -34.2 -29.6 235 71 37 8.0 4.4 | -34.6 -30.3 235 73 38 8.0 4.4
26000 -31.8 -25.2 235 69 36 7.9 4.3 | -31.8 -25.2 235 70 36 7.6 4.2
25000 -28.9 -20.0 235 67 34 7.9 4.3 | -29.5 -21.1 240 67 35 7.6 4.2
24000 -26.6 -15.9 240 64 33 6.6 3.6 | -27.2 -17.0 240 64 33 7.5 4.1
23000 -24.6 -12.3 240 57 29 6.7 3.7 | -25.0 -13.0 240 60 31 7.5 4.1
22000 -22.6 -8.7 240 51 26 6.7 3.7 | -22.7 -8.9 240 56 29 7.5 4.1
21000 -20.6 -5.1 240 46 24 6.8 3.8 | -20.7 -5.3 240 51 26 6.1 3.4
20000 -18.6 -1.5 240 44 23 6.9 3.8 | -18.8 -1.8 240 47 24 6.2 3.4
19500 -17.6 0.3 240 43 22 6.9 3.8 | -17.9 -0.2 240 45 23 6.2 3.4
19000 -16.6 2.1 240 41 21 6.8 3.7 | -17.0 1.4 240 43 22 6.1 3.4
18500 -15.6 3.9 240 41 21 7.4 4.1 | -16.0 3.2 240 41 21 7.1 3.9
18000 -14.5 5.9 235 41 21 7.4 4.0 | -15.0 5.0 235 40 21 7.0 3.8
17500 -13.4 7.9 235 40 21 7.3 4.0 | -13.9 7.0 235 39 20 6.9 3.8
17000 -12.3 9.9 235 40 21 7.3 4.0 | -12.9 8.8 235 38 20 6.9 3.8
16500 -11.2 11.8 235 40 20 7.3 4.0 | -11.9 10.6 235 38 19 6.9 3.8
16000 -10.1 13.8 235 39 20 7.4 4.1 | -10.9 12.4 235 37 19 7.1 3.9
15500 -9.0 15.8 235 39 20 7.4 4.0 | -9.8 14.4 235 36 19 7.1 3.9
15000 -7.9 17.8 235 38 20 7.7 4.2 | -8.7 16.3 235 36 18 7.4 4.1
14500 -6.7 19.9 240 38 19 7.7 4.2 | -7.6 18.3 235 35 18 7.4 4.1
14000 -5.6 21.9 240 37 19 7.7 4.2 | -6.5 20.3 235 34 18 7.6 4.2
13500 -4.4 24.1 240 37 19 7.7 4.2 | -5.4 22.3 235 33 17 7.7 4.2
13000 -3.3 26.1 240 36 18 7.8 4.3 | -4.2 24.4 235 33 17 7.9 4.3
12500 -2.1 28.2 240 35 18 7.9 4.3 | -3.0 26.6 235 32 16 8.0 4.4
12000 -1.0 30.2 240 34 17 7.8 4.3 | -1.9 28.6 235 31 16 8.2 4.5
11500 0.2 32.4 240 33 17 7.7 4.2 | -0.6 30.9 230 30 15 8.3 4.6
11000 1.3 34.3 240 31 16 7.2 3.9 | 0.6 33.1 230 29 15 8.2 4.5
10500 2.3 36.1 240 30 15 5.8 3.2 | 1.8 35.2 230 28 14 7.8 4.3
10250 2.8 37.0 240 29 15 10.1 5.5 | 2.4 36.3 230 27 14 9.3 5.1
10000 3.7 38.7 235 28 14 10.8 5.9 | 3.2 37.8 225 26 14 9.4 5.2
9750 4.3 39.7 235 27 14 7.0 3.8 | 3.8 38.8 225 25 13 8.1 4.4
9500 4.9 40.8 230 25 13 8.2 4.5 | 4.4 39.9 225 24 13 8.2 4.5
9250 5.5 41.9 230 24 13 7.3 4.0 | 5.1 41.2 220 24 12 8.9 4.9
9000 6.0 42.8 230 24 12 6.2 3.4 | 6.3 43.3 220 21 11 6.7 3.7
8750 7.0 44.6 225 21 11 6.8 3.7 | 6.8 44.2 215 20 11 6.6 3.6
8500 7.5 45.5 220 20 10 6.8 3.7 | 7.3 45.1 215 19 10 7.0 3.8
8250 8.0 46.4 220 19 10 6.6 3.6 | 7.9 46.2 210 19 10 7.3 4.0
8000 8.4 47.1 215 17 9 5.1 2.8 | 8.4 47.1 210 18 9 6.2 3.4
7750 8.8 47.8 210 16 8 4.2 2.3 | 8.8 47.8 205 16 8 5.6 3.1
7500 9.1 48.4 200 14 7 5.1 2.8 | 9.2 48.6 200 15 8 5.8 3.2
7250 9.5 49.1 200 14 7 6.0 3.3 | 9.7 49.5 195 15 8 5.8 3.2
7000 9.9 49.8 195 14 7 4.4 2.4 | 10.1 50.2 190 15 7 5.6 3.1
6750 10.2 50.4 185 12 6 2.7 1.5 | 10.5 50.9 185 13 7 5.8 3.2
6500 10.4 50.7 175 11 6 1.4 0.8 | 11.0 51.8 180 12 6 6.3 3.4
6250 10.4 50.7 170 10 5 0.6 0.3 | 11.4 52.5 175 11 5 7.2 3.9
6000 10.5 50.9 160 10 5 0.7 0.4 | 11.9 53.4 170 10 5 4.4 2.4
5750 10.1 50.2 150 6 3 -13.8 -7.6 | 12.1 53.8 165 7 4 4.1 2.3
5500 7.0 44.6 115 4 2 -82.0 -45.0 | 13.5 56.3 155 6 3 45.5 25.0
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
02/04/2025 at 1400 MST | 02/04/2025 at 1700 MST
|
CAPE... 0.0 LI... +2.0 | CAPE... +1.3 LI... +1.2
CINH... -0.2 K Index... +19.4 | CINH... -9.9 K Index... +20.6
|
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 -62.3 -80.1 270 61 31 4.2 2.3 | -62.3 -80.1 270 68 35 4.3 2.4
45000 -55.9 -68.6 265 78 40 5.1 2.8 | -55.7 -68.3 275 89 46 5.5 3.0
40000 -47.9 -54.2 265 82 42 4.9 2.7 | -47.0 -52.6 270 92 47 5.3 2.9
38000 -47.2 -53.0 260 81 42 -0.2 -0.1 | -45.3 -49.5 265 88 45 2.0 1.1
36000 -47.3 -53.1 250 80 41 -0.2 -0.1 | -44.1 -47.4 260 82 42 2.0 1.1
34000 -47.0 -52.6 240 81 42 2.4 1.3 | -43.2 -45.8 255 78 40 -0.4 -0.2
32000 -45.5 -49.9 235 80 41 2.5 1.4 | -43.5 -46.3 245 74 38 -0.5 -0.3
30000 -43.1 -45.6 230 78 40 8.1 4.4 | -43.0 -45.4 235 73 37 6.4 3.5
29000 -40.7 -41.3 230 76 39 8.2 4.5 | -41.1 -42.0 235 71 37 6.3 3.5
28000 -38.2 -36.8 230 74 38 8.3 4.5 | -39.2 -38.6 235 70 36 6.3 3.5
27000 -35.7 -32.3 230 72 37 7.8 4.3 | -36.8 -34.2 235 68 35 8.1 4.5
26000 -32.9 -27.2 230 68 35 7.5 4.1 | -34.3 -29.7 235 65 34 8.2 4.5
25000 -30.7 -23.3 235 65 33 7.5 4.1 | -31.8 -25.2 235 62 32 8.2 4.5
24000 -28.5 -19.3 235 62 32 7.8 4.3 | -29.4 -20.9 235 59 31 7.9 4.3
23000 -26.1 -15.0 235 59 30 7.9 4.3 | -27.1 -16.8 235 57 30 7.7 4.2
22000 -23.8 -10.8 235 56 29 7.9 4.3 | -24.8 -12.6 235 56 29 7.7 4.2
21000 -21.4 -6.5 235 53 27 7.4 4.1 | -22.5 -8.5 235 53 27 7.6 4.2
20000 -19.2 -2.6 235 50 26 7.5 4.1 | -20.2 -4.4 235 50 26 7.7 4.2
19500 -18.1 -0.6 235 49 25 7.5 4.1 | -19.0 -2.2 235 49 25 7.7 4.2
19000 -17.0 1.4 235 47 24 7.6 4.2 | -17.9 -0.2 235 47 24 7.7 4.2
18500 -16.0 3.2 235 45 23 6.8 3.7 | -16.8 1.8 235 46 24 7.3 4.0
18000 -15.0 5.0 235 44 23 6.7 3.7 | -15.7 3.7 235 45 23 7.2 4.0
17500 -14.0 6.8 235 42 22 6.8 3.7 | -14.7 5.5 235 45 23 7.2 4.0
17000 -13.0 8.6 235 40 21 6.8 3.7 | -13.6 7.5 235 43 22 7.2 3.9
16500 -12.0 10.4 235 39 20 6.8 3.8 | -12.6 9.3 235 42 22 7.2 3.9
16000 -11.0 12.2 230 37 19 6.9 3.8 | -11.5 11.3 235 40 21 7.5 4.1
15500 -10.0 14.0 230 36 18 6.9 3.8 | -10.4 13.3 235 39 20 7.5 4.1
15000 -8.9 16.0 230 34 17 7.1 3.9 | -9.3 15.3 235 37 19 7.7 4.2
14500 -7.9 17.8 230 32 17 7.2 3.9 | -8.2 17.2 235 35 18 7.8 4.3
14000 -6.8 19.8 230 31 16 7.5 4.1 | -7.0 19.4 230 33 17 8.1 4.4
13500 -5.7 21.7 230 29 15 7.7 4.2 | -5.8 21.6 230 31 16 8.3 4.6
13000 -4.5 23.9 225 28 14 8.0 4.4 | -4.6 23.7 230 29 15 8.4 4.6
12500 -3.3 26.1 225 26 14 8.4 4.6 | -3.3 26.1 225 28 14 8.6 4.7
12000 -2.0 28.4 225 25 13 8.5 4.7 | -2.0 28.4 225 27 14 8.6 4.7
11500 -0.7 30.7 220 24 13 8.6 4.7 | -0.7 30.7 220 26 13 8.7 4.8
11000 0.5 32.9 220 23 12 8.3 4.6 | 0.6 33.1 220 26 13 8.5 4.7
10500 1.7 35.1 220 22 12 7.4 4.1 | 1.8 35.2 220 26 13 7.6 4.2
10250 2.3 36.1 220 22 11 9.6 5.3 | 2.4 36.3 215 26 13 9.0 4.9
10000 3.1 37.6 215 22 11 10.6 5.8 | 3.1 37.6 215 26 13 10.2 5.6
9750 3.8 38.8 215 22 11 8.5 4.7 | 3.9 39.0 210 26 14 9.0 4.9
9500 4.5 40.1 210 21 11 8.4 4.6 | 4.5 40.1 210 26 14 8.6 4.7
9250 5.1 41.2 210 21 11 8.5 4.6 | 5.2 41.4 210 26 14 8.7 4.8
9000 5.7 42.3 210 20 10 8.5 4.7 | 6.5 43.7 205 26 13 8.8 4.8
8750 7.0 44.6 210 19 10 8.4 4.6 | 7.1 44.8 205 25 13 8.7 4.8
8500 7.6 45.7 205 19 10 8.4 4.6 | 7.8 46.0 205 25 13 8.7 4.8
8250 8.2 46.8 205 19 10 8.0 4.4 | 8.4 47.1 205 25 13 8.7 4.8
8000 8.8 47.8 205 18 9 8.0 4.4 | 9.1 48.4 205 25 13 8.6 4.7
7750 9.5 49.1 200 17 9 8.2 4.5 | 9.7 49.5 200 24 12 8.6 4.7
7500 10.1 50.2 200 16 8 8.1 4.5 | 10.3 50.5 200 23 12 8.3 4.5
7250 10.7 51.3 200 16 8 8.1 4.5 | 10.9 51.6 200 23 12 7.5 4.1
7000 11.3 52.3 200 15 8 9.3 5.1 | 11.5 52.7 200 23 12 8.1 4.4
6750 12.0 53.6 200 15 7 10.2 5.6 | 12.1 53.8 195 21 11 8.7 4.8
6500 12.8 55.0 200 14 7 10.5 5.8 | 12.8 55.0 195 18 9 8.4 4.6
6250 13.6 56.5 200 13 7 11.8 6.4 | 13.4 56.1 195 18 9 8.6 4.7
6000 14.5 58.1 200 13 7 8.4 4.6 | 14.0 57.2 195 17 9 7.1 3.9
5750 14.9 58.8 200 12 6 7.7 4.2 | 14.3 57.7 195 13 7 1.4 0.8
5500 16.7 62.1 200 10 5 51.0 28.0 | 14.1 57.4 190 9 4 -5.5 -3.0
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
________________________________________________________________________________
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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