Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
082
UXUS97 KGJT 241306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Saturday, May 24, 2025
This forecast is for Saturday, May 24, 2025:
If the trigger temperature of 71.2 F/21.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1903 ft/min (9.7 m/s)
Maximum height of thermals.................. 25113 ft MSL (19506 ft AGL)
Forecast maximum temperature................... 87.0 F/31.0 C
Time of trigger temperature.................... 0845 MDT
Time of overdevelopment........................ 1800 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 20563 ft MSL (14956 ft AGL)
Thermal soaring outlook for Sunday 05/25....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:53:45 / 20:28:21 MDT
Total possible sunshine........... 14 hr 34 min 36 sec (874 min 36 sec)
Altitude of sun at 13:11:03 MDT... 71.65 degrees
Upper air data from rawinsonde observation taken on 05/24/2025 at 0600 MDT
Freezing level.................. 13522 ft MSL (7915 ft AGL)
Convective condensation level... 18032 ft MSL (12425 ft AGL)
Lifted condensation level....... 20344 ft MSL (14738 ft AGL)
Lifted index.................... -3.7
K index......................... +11.5
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 -58.9 -74.0 245 29 15 1.5 0.8 M M M M M
45000 -56.9 -70.4 240 35 18 0.1 0.1 M M M M M
40000 -56.7 -70.1 230 60 31 0.2 0.1 M M M M M
38000 -54.8 -66.6 225 61 31 3.8 2.1 M M M M M
36000 -52.5 -62.5 225 59 31 3.8 2.1 M M M M M
34000 -49.4 -56.9 225 56 29 6.8 3.7 M M M M M
32000 -45.3 -49.5 220 51 26 6.8 3.7 M M M M M
30000 -40.8 -41.4 220 46 24 8.2 4.5 33.4 92.2 2.1 M M
29000 -38.4 -37.1 220 44 23 8.2 4.5 32.8 91.0 1.7 M M
28000 -35.9 -32.6 225 41 21 8.2 4.5 32.3 90.1 1.3 M M
27000 -33.4 -28.1 225 39 20 8.3 4.6 31.7 89.1 0.9 M M
26000 -30.9 -23.6 225 38 19 8.3 4.6 31.1 88.0 0.4 M M
25000 -28.4 -19.1 225 36 18 8.3 4.6 30.6 87.1 -0.0 1898 9.6
24000 -26.0 -14.8 225 34 18 7.5 4.1 30.1 86.1 -0.5 1796 9.1
23000 -23.7 -10.7 225 32 16 7.6 4.2 29.2 84.5 -1.2 1698 8.6
22000 -21.5 -6.7 225 30 15 7.6 4.2 28.5 83.2 -1.8 1600 8.1
21000 -18.7 -1.7 220 27 14 7.4 4.1 27.4 81.4 -2.7 1480 7.5
20000 -16.5 2.3 215 25 13 7.4 4.1 26.6 79.9 -3.5 1384 7.0
19500 -15.4 4.3 210 25 13 7.5 4.1 26.2 79.2 -3.9 1337 6.8
19000 -14.3 6.3 210 24 12 7.6 4.2 25.9 78.6 -4.2 1289 6.5
18500 -13.2 8.2 210 22 11 7.7 4.2 25.5 77.9 -4.6 1240 6.3
18000 -12.0 10.4 205 20 10 7.6 4.2 25.2 77.3 -5.0 1191 6.1
17500 -10.8 12.6 205 17 9 8.7 4.8 24.9 76.8 -5.2 1141 5.8
17000 -9.6 14.7 205 15 8 8.7 4.8 24.7 76.5 -5.5 1088 5.5
16500 -8.3 17.1 210 13 7 9.0 5.0 24.6 76.2 -5.7 1035 5.3
16000 -6.9 19.6 210 12 6 9.2 5.0 24.4 76.0 -5.8 978 5.0
15500 -5.5 22.1 215 10 5 9.2 5.1 24.4 75.9 -5.9 922 4.7
15000 -4.1 24.6 220 10 5 9.4 5.2 24.3 75.7 -6.0 865 4.4
14500 -2.7 27.1 225 9 5 9.4 5.2 24.2 75.6 -6.1 808 4.1
14000 -1.3 29.7 225 9 5 9.2 5.1 24.2 75.5 -6.2 752 3.8
13500 0.1 32.2 230 9 5 9.2 5.1 24.1 75.3 -6.3 695 3.5
13000 1.5 34.7 235 9 4 9.1 5.0 24.0 75.2 -6.4 639 3.2
12500 2.8 37.0 235 8 4 9.1 5.0 23.9 75.0 -6.6 583 3.0
12000 4.2 39.6 235 8 4 8.9 4.9 23.8 74.8 -6.7 528 2.7
11500 5.5 41.9 235 7 4 9.0 5.0 23.6 74.5 -6.9 473 2.4
11000 6.7 44.1 235 7 3 6.9 3.8 23.4 74.1 -7.1 421 2.1
10500 7.7 45.9 225 6 3 7.9 4.3 22.9 73.1 -7.7 378 1.9
10250 8.4 47.1 220 5 3 8.8 4.8 22.8 73.0 -7.7 350 1.8
10000 8.9 48.0 210 5 2 6.7 3.7 22.6 72.7 -7.9 326 1.7
9750 9.4 48.9 200 4 2 6.1 3.4 22.3 72.2 -8.2 305 1.5
9500 9.9 49.8 190 4 2 6.3 3.4 22.1 71.7 -8.5 283 1.4
9250 10.4 50.7 175 3 2 6.8 3.7 21.8 71.3 -8.8 262 1.3
9000 10.9 51.6 155 3 2 7.0 3.9 21.6 70.9 -9.0 238 1.2
8750 11.4 52.5 140 3 2 6.8 3.7 21.4 70.5 -9.3 216 1.1
8500 11.9 53.4 130 4 2 7.1 3.9 21.1 70.1 -9.5 193 1.0
8250 12.4 54.3 125 4 2 6.1 3.4 20.9 69.7 -9.8 171 0.9
8000 12.7 54.9 110 4 2 4.5 2.5 20.6 69.0 -10.2 153 0.8
7750 13.0 55.4 100 4 2 4.4 2.4 20.2 68.3 -10.6 137 0.7
7500 13.3 55.9 090 5 2 4.1 2.3 19.7 67.5 -11.1 121 0.6
7250 13.5 56.3 085 5 3 1.3 0.7 19.2 66.6 -11.7 108 0.5
7000 13.4 56.1 080 6 3 -0.2 -0.1 18.5 65.3 -12.5 103 0.5
6750 13.4 56.1 075 6 3 1.8 1.0 17.8 64.0 -13.3 95 0.5
6500 13.4 56.1 075 6 3 -2.3 -1.3 17.1 62.8 -14.0 88 0.4
6250 12.9 55.2 070 6 3 -10.2 -5.6 15.9 60.6 -15.3 96 0.5
6000 12.2 54.0 070 6 3 -4.1 -2.3 14.5 58.0 -16.8 110 0.6
5750 12.1 53.8 070 6 3 -3.3 -1.8 13.7 56.6 -17.7 105 0.5
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 * * * * * *
05/24/2025 at 0900 MDT | 05/24/2025 at 1200 MDT
|
CAPE... 0.0 LI... +1.9 | CAPE... 0.0 LI... +2.7
CINH... -0.2 K Index... +9.4 | CINH... 0.0 K Index... +7.5
|
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 -60.2 -76.4 245 31 16 1.8 1.0 | -60.0 -76.0 240 32 16 1.5 0.8
45000 -58.1 -72.6 245 44 23 -1.2 -0.7 | -58.2 -72.8 240 42 21 -1.0 -0.6
40000 -60.1 -76.2 240 63 32 -1.0 -0.5 | -59.9 -75.8 235 64 33 -0.8 -0.4
38000 -56.6 -69.9 245 60 31 6.5 3.5 | -56.6 -69.9 235 62 32 6.2 3.4
36000 -52.7 -62.9 245 56 29 6.5 3.5 | -52.9 -63.2 235 60 31 6.2 3.4
34000 -48.1 -54.6 245 53 27 8.8 4.8 | -48.2 -54.8 235 56 29 9.0 4.9
32000 -42.8 -45.0 245 51 26 8.8 4.8 | -42.9 -45.2 235 52 27 9.0 4.9
30000 -37.8 -36.0 245 50 26 8.1 4.5 | -37.6 -35.7 235 50 26 8.6 4.7
29000 -35.3 -31.5 240 50 26 8.1 4.5 | -35.0 -31.0 235 50 26 8.6 4.7
28000 -32.9 -27.2 240 50 26 8.1 4.5 | -32.5 -26.5 240 50 26 8.6 4.7
27000 -30.5 -22.9 240 49 25 7.8 4.3 | -30.1 -22.2 235 50 26 7.1 3.9
26000 -28.2 -18.8 235 47 24 7.8 4.3 | -28.0 -18.4 235 48 25 7.1 3.9
25000 -25.8 -14.4 235 45 23 7.8 4.3 | -25.9 -14.6 235 47 24 7.1 3.9
24000 -23.1 -9.6 235 42 21 6.5 3.6 | -23.2 -9.8 230 44 23 7.2 4.0
23000 -21.2 -6.2 230 39 20 6.5 3.6 | -21.0 -5.8 235 41 21 7.3 4.0
22000 -19.2 -2.6 230 36 19 6.5 3.6 | -18.7 -1.7 235 37 19 7.4 4.0
21000 -17.4 0.7 225 34 17 6.2 3.4 | -16.7 1.9 230 34 18 6.7 3.6
20000 -15.5 4.1 220 32 16 6.3 3.4 | -14.7 5.5 230 31 16 6.7 3.6
19500 -14.6 5.7 220 31 16 6.3 3.5 | -13.7 7.3 230 30 15 6.6 3.6
19000 -13.7 7.3 215 30 16 7.0 3.8 | -12.7 9.1 225 28 15 6.3 3.5
18500 -12.6 9.3 215 29 15 7.6 4.2 | -11.8 10.8 225 27 14 6.0 3.3
18000 -11.4 11.5 215 28 14 7.6 4.2 | -11.0 12.2 220 25 13 5.8 3.2
17500 -10.2 13.6 215 27 14 8.7 4.8 | -10.0 14.0 220 23 12 7.3 4.0
17000 -9.0 15.8 215 25 13 8.6 4.7 | -8.9 16.0 220 22 11 7.3 4.0
16500 -7.7 18.1 215 24 12 8.9 4.9 | -7.9 17.8 215 20 10 7.9 4.3
16000 -6.3 20.7 215 22 11 9.1 5.0 | -6.7 19.9 215 19 10 8.2 4.5
15500 -5.0 23.0 220 21 11 9.1 5.0 | -5.5 22.1 215 17 9 8.4 4.6
15000 -3.6 25.5 220 19 10 9.0 4.9 | -4.2 24.4 210 16 8 9.0 4.9
14500 -2.3 27.9 225 17 9 9.0 5.0 | -2.9 26.8 210 15 8 8.9 4.9
14000 -1.0 30.2 230 16 8 8.5 4.6 | -1.5 29.3 210 14 7 9.4 5.1
13500 0.2 32.4 230 14 7 8.5 4.7 | -0.1 31.8 210 14 7 9.3 5.1
13000 1.5 34.7 235 13 7 8.8 4.8 | 1.3 34.3 210 13 7 9.4 5.2
12500 2.8 37.0 240 12 6 8.8 4.8 | 2.7 36.9 210 12 6 9.4 5.2
12000 4.1 39.4 245 12 6 8.9 4.9 | 4.1 39.4 215 12 6 9.5 5.2
11500 5.5 41.9 245 13 6 9.0 4.9 | 5.5 41.9 215 11 6 9.5 5.2
11000 6.7 44.1 250 13 7 7.3 4.0 | 6.9 44.4 220 11 6 8.4 4.6
10500 7.8 46.0 245 14 7 6.0 3.3 | 8.1 46.6 220 11 5 7.4 4.0
10250 8.3 46.9 245 14 7 10.4 5.7 | 8.7 47.7 220 10 5 11.9 6.5
10000 9.2 48.6 245 13 7 11.0 6.1 | 9.8 49.6 220 11 5 12.5 6.8
9750 9.8 49.6 245 13 7 6.9 3.8 | 10.5 50.9 220 10 5 8.4 4.6
9500 10.4 50.7 245 13 7 8.5 4.6 | 11.2 52.2 225 10 5 9.9 5.4
9250 11.0 51.8 245 13 7 6.4 3.5 | 11.9 53.4 225 10 5 8.1 4.4
9000 11.4 52.5 245 14 7 6.4 3.5 | 12.4 54.3 225 10 5 8.5 4.7
8750 12.6 54.7 240 12 6 7.9 4.3 | 13.9 57.0 225 9 5 10.0 5.5
8500 13.2 55.8 235 11 6 6.9 3.8 | 14.6 58.3 225 9 5 9.2 5.0
8250 13.6 56.5 235 11 5 6.2 3.4 | 15.3 59.5 230 9 4 9.2 5.0
8000 14.1 57.4 235 10 5 7.1 3.9 | 16.0 60.8 230 8 4 10.3 5.7
7750 14.7 58.5 230 9 5 7.4 4.1 | 16.8 62.2 230 8 4 10.7 5.9
7500 15.2 59.4 220 8 4 5.9 3.2 | 17.6 63.7 230 8 4 9.0 4.9
7250 15.6 60.1 220 7 4 5.1 2.8 | 18.2 64.8 230 8 4 8.1 4.4
7000 16.1 61.0 220 6 3 8.3 4.5 | 18.9 66.0 235 8 4 10.6 5.8
6750 16.8 62.2 210 6 3 9.8 5.4 | 19.7 67.5 230 8 4 11.6 6.3
6500 17.5 63.5 205 6 3 9.2 5.0 | 20.5 68.9 230 8 4 10.9 6.0
6250 18.2 64.8 200 5 2 9.6 5.3 | 21.4 70.5 235 7 4 11.6 6.4
6000 18.8 65.8 200 4 2 7.8 4.3 | 22.2 72.0 240 7 4 7.8 4.3
5750 19.4 66.9 200 5 3 10.5 5.8 | 22.7 72.9 235 7 4 11.4 6.3
5500 21.3 70.3 190 3 1 51.0 28.0 | 25.6 78.1 240 7 3 87.4 48.0
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
05/24/2025 at 1500 MDT | 05/24/2025 at 1800 MDT
|
CAPE... 0.0 LI... +1.0 | CAPE... 0.0 LI... +1.3
CINH... -0.0 K Index... +5.1 | CINH... -0.2 K Index... -0.4
|
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 -59.9 -75.8 245 35 18 0.9 0.5 | -59.3 -74.7 245 32 17 0.3 0.2
45000 -58.8 -73.8 235 46 24 -0.6 -0.3 | -58.9 -74.0 235 46 24 -0.4 -0.2
40000 -59.8 -75.6 230 65 34 -0.3 -0.2 | -59.5 -75.1 225 62 32 -0.6 -0.4
38000 -56.6 -69.9 230 66 34 6.0 3.3 | -56.6 -69.9 225 64 33 5.6 3.0
36000 -53.0 -63.4 225 67 34 6.0 3.3 | -53.2 -63.8 225 65 34 5.5 3.0
34000 -48.4 -55.1 230 64 33 8.9 4.9 | -48.8 -55.8 220 64 33 8.9 4.9
32000 -43.1 -45.6 230 58 30 8.9 4.9 | -43.5 -46.3 220 60 31 8.9 4.9
30000 -37.9 -36.2 230 55 28 8.5 4.7 | -38.4 -37.1 225 55 28 8.1 4.4
29000 -35.3 -31.5 230 54 28 8.5 4.7 | -36.0 -32.8 225 52 27 8.1 4.4
28000 -32.8 -27.0 230 53 27 8.5 4.7 | -33.6 -28.5 230 48 25 8.1 4.4
27000 -30.3 -22.5 230 52 27 7.9 4.4 | -31.2 -24.2 230 46 24 8.0 4.4
26000 -27.9 -18.2 225 49 25 7.9 4.3 | -28.8 -19.8 230 43 22 8.0 4.4
25000 -25.6 -14.1 225 47 24 7.9 4.4 | -26.4 -15.5 230 41 21 8.1 4.4
24000 -23.0 -9.4 225 43 22 5.9 3.2 | -23.7 -10.7 230 38 20 6.5 3.6
23000 -21.2 -6.2 225 39 20 5.9 3.2 | -21.8 -7.2 230 36 19 6.4 3.5
22000 -19.4 -2.9 225 34 18 5.8 3.2 | -19.8 -3.6 230 34 17 6.4 3.5
21000 -17.5 0.5 225 30 15 6.5 3.6 | -17.8 -0.0 230 31 16 7.3 4.0
20000 -15.6 3.9 220 26 13 6.6 3.6 | -15.6 3.9 230 29 15 7.3 4.0
19500 -14.6 5.7 220 23 12 6.6 3.6 | -14.5 5.9 230 27 14 7.3 4.0
19000 -13.7 7.3 220 21 11 7.3 4.0 | -13.4 7.9 230 26 13 8.1 4.4
18500 -12.5 9.5 220 21 11 7.9 4.3 | -12.1 10.2 225 25 13 8.7 4.8
18000 -11.3 11.7 220 20 10 7.9 4.3 | -10.7 12.7 225 24 12 8.7 4.8
17500 -10.1 13.8 215 19 10 9.2 5.1 | -9.4 15.1 220 23 12 9.1 5.0
17000 -8.7 16.3 215 19 10 9.1 5.0 | -8.1 17.4 220 22 11 9.1 5.0
16500 -7.3 18.9 215 19 10 9.4 5.2 | -6.7 19.9 220 21 11 9.0 4.9
16000 -5.9 21.4 215 18 10 9.5 5.2 | -5.4 22.3 220 21 11 9.0 4.9
15500 -4.5 23.9 215 18 9 9.5 5.2 | -4.0 24.8 220 20 10 9.0 4.9
15000 -3.1 26.4 215 18 9 9.4 5.1 | -2.7 27.1 220 20 10 8.9 4.9
14500 -1.7 28.9 215 18 9 9.4 5.1 | -1.4 29.5 220 19 10 8.9 4.9
14000 -0.2 31.6 220 17 9 9.5 5.2 | 0.0 32.0 220 19 10 9.3 5.1
13500 1.2 34.2 220 17 9 9.5 5.2 | 1.4 34.5 225 18 9 9.3 5.1
13000 2.6 36.7 220 17 9 9.1 5.0 | 2.8 37.0 225 18 9 9.0 4.9
12500 3.9 39.0 220 16 8 9.1 5.0 | 4.1 39.4 230 18 9 9.0 4.9
12000 5.3 41.5 225 16 8 9.3 5.1 | 5.5 41.9 230 18 9 9.2 5.0
11500 6.7 44.1 225 16 8 9.4 5.1 | 6.9 44.4 235 17 9 9.3 5.1
11000 8.0 46.4 230 15 8 8.2 4.5 | 8.2 46.8 235 17 9 8.0 4.4
10500 9.2 48.6 235 15 8 7.7 4.2 | 9.3 48.7 240 17 9 7.3 4.0
10250 9.9 49.8 235 14 7 11.2 6.2 | 10.0 50.0 240 17 9 11.7 6.4
10000 10.8 51.4 235 15 8 11.4 6.3 | 11.0 51.8 240 17 9 12.0 6.6
9750 11.5 52.7 235 15 8 8.6 4.7 | 11.7 53.1 240 17 9 8.2 4.5
9500 12.2 54.0 240 15 8 9.6 5.3 | 12.4 54.3 245 16 8 9.6 5.3
9250 12.9 55.2 240 15 8 8.4 4.6 | 13.0 55.4 245 16 8 7.8 4.3
9000 13.5 56.3 245 14 7 9.1 5.0 | 13.6 56.5 245 16 8 8.3 4.6
8750 14.3 57.7 245 15 8 10.5 5.8 | 14.3 57.7 245 16 8 10.1 5.5
8500 15.8 60.4 245 15 8 9.6 5.3 | 15.8 60.4 250 15 8 8.8 4.8
8250 16.5 61.7 250 15 8 9.5 5.2 | 16.4 61.5 250 15 8 8.7 4.8
8000 17.3 63.1 250 15 8 10.4 5.7 | 17.1 62.8 250 15 8 10.2 5.6
7750 18.0 64.4 250 15 8 10.7 5.9 | 17.9 64.2 250 15 8 10.6 5.8
7500 18.8 65.8 250 15 8 9.1 5.0 | 18.6 65.5 250 15 8 9.0 4.9
7250 19.4 66.9 250 15 8 8.3 4.5 | 19.2 66.6 255 15 8 7.9 4.3
7000 20.1 68.2 250 15 8 10.7 5.9 | 19.9 67.8 255 15 8 10.1 5.6
6750 21.0 69.8 250 15 8 11.6 6.3 | 20.7 69.3 255 14 7 10.9 6.0
6500 21.8 71.2 250 14 7 10.8 5.9 | 21.5 70.7 255 14 7 10.4 5.7
6250 22.6 72.7 255 14 7 11.4 6.3 | 22.3 72.1 255 14 7 10.8 5.9
6000 23.4 74.1 255 15 7 7.7 4.2 | 23.0 73.4 260 14 7 8.2 4.5
5750 24.0 75.2 250 13 7 12.1 6.7 | 23.6 74.5 255 12 6 7.8 4.3
5500 27.1 80.8 260 13 6 90.7 49.8 | 25.0 77.0 260 11 6 42.4 23.3
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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