Soaring Forecast GJT

 Grand Junction Soaring Forecast

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653
UXUS97 KGJT 281306
SRGGJT

Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Friday, March 28, 2025

This forecast is for Friday, March 28, 2025:

If the trigger temperature of 50.3 F/10.2 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1283 ft/min (6.5 m/s)
Maximum height of thermals.................. 24144 ft MSL (18536 ft AGL)

Forecast maximum temperature................... 73.0 F/23.2 C
Time of trigger temperature.................... None
Time of overdevelopment........................ None
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................. 19414 ft MSL (13806 ft AGL)
Thermal soaring outlook for Saturday 03/29..... Good

Wave Soaring Index............................. Not available

Remarks...

Sunrise/Sunset.................... 07:03:54 / 19:34:06 MDT
Total possible sunshine........... 12 hr 30 min 11 sec (750 min 11 sec)
Altitude of sun at 13:19:00 MDT... 53.93 degrees

Upper air data from rawinsonde observation taken on 03/28/2025 at 0600 MDT

Freezing level.................. 8678 ft MSL (3070 ft AGL)
Convective condensation level... 10192 ft MSL (4584 ft AGL)
Lifted condensation level....... 15063 ft MSL (9455 ft AGL)
Lifted index.................... -7.8
K index......................... +19.5

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 -56.3 -69.3 240 31 16 1.6 0.9 M M M M M
45000 -53.8 -64.8 235 38 19 1.7 0.9 M M M M M
40000 -53.2 -63.8 230 40 20 0.3 0.2 M M M M M
38000 -53.1 -63.6 230 40 20 -0.3 -0.2 M M M M M
36000 -53.3 -63.9 235 38 20 -0.3 -0.2 M M M M M
34000 -53.5 -64.3 235 37 19 1.7 0.9 M M M M M
32000 -50.8 -59.4 240 34 18 4.7 2.6 M M M M M
30000 -48.0 -54.4 240 32 17 6.8 3.7 26.8 80.3 3.0 M M
29000 -45.5 -49.9 240 31 16 8.3 4.5 26.1 78.9 2.5 M M
28000 -43.0 -45.4 240 29 15 8.3 4.5 25.5 77.9 2.1 M M
27000 -40.5 -40.9 245 27 14 8.3 4.5 25.0 77.0 1.7 M M
26000 -38.2 -36.8 245 27 14 7.7 4.2 24.3 75.8 1.2 M M
25000 -35.9 -32.6 245 26 13 7.7 4.2 23.5 74.3 0.5 M M
24000 -33.5 -28.3 245 26 13 7.7 4.2 22.8 73.0 -0.0 1675 8.5
23000 -31.2 -24.2 245 26 13 8.0 4.4 22.1 71.8 -0.6 1575 8.0
22000 -28.8 -19.8 250 26 13 8.0 4.4 21.4 70.5 -1.2 1474 7.5
21000 -26.4 -15.5 250 26 14 8.0 4.4 20.8 69.5 -1.7 1373 7.0
20000 -23.6 -10.5 250 25 13 7.4 4.1 19.8 67.6 -2.6 1252 6.4
19500 -22.5 -8.5 250 25 13 7.4 4.1 19.4 66.9 -3.0 1205 6.1
19000 -21.4 -6.5 250 24 12 7.4 4.1 19.0 66.2 -3.4 1157 5.9
18500 -20.3 -4.5 250 24 12 7.3 4.0 18.6 65.5 -3.7 1109 5.6
18000 -19.3 -2.7 245 23 12 6.8 3.7 18.2 64.7 -4.2 1064 5.4
17500 -18.3 -0.9 245 22 12 6.8 3.7 17.7 63.8 -4.7 1019 5.2
17000 -17.3 0.9 245 22 11 6.9 3.8 17.2 62.9 -5.1 974 4.9
16500 -16.3 2.7 240 21 11 6.9 3.8 16.7 62.0 -5.6 928 4.7
16000 -15.2 4.6 240 21 11 6.9 3.8 16.2 61.2 -6.1 882 4.5
15500 -14.2 6.4 240 20 11 6.9 3.8 15.7 60.3 -6.6 837 4.3
15000 -13.2 8.2 240 20 10 6.9 3.8 15.3 59.5 -7.0 792 4.0
14500 -12.2 10.0 240 20 10 7.1 3.9 14.8 58.7 -7.5 746 3.8
14000 -11.1 12.0 240 20 10 7.1 3.9 14.4 57.9 -8.0 700 3.6
13500 -10.1 13.8 240 20 10 7.5 4.1 14.0 57.2 -8.4 653 3.3
13000 -9.0 15.8 240 20 10 7.4 4.1 13.6 56.5 -8.9 606 3.1
12500 -7.9 17.8 240 20 10 7.6 4.2 13.2 55.8 -9.3 558 2.8
12000 -6.8 19.8 240 19 10 7.6 4.2 12.9 55.2 -9.7 510 2.6
11500 -5.7 21.7 240 19 10 7.3 4.0 12.5 54.5 -10.1 463 2.4
11000 -4.6 23.7 240 18 9 7.4 4.1 12.1 53.8 -10.6 416 2.1
10500 -3.6 25.5 240 16 8 6.3 3.4 11.7 53.0 -11.1 372 1.9
10250 -3.2 26.2 240 16 8 6.9 3.8 11.4 52.6 -11.4 350 1.8
10000 -2.7 27.1 240 15 8 7.2 4.0 11.2 52.2 -11.6 328 1.7
9750 -2.1 28.2 240 14 7 7.0 3.8 11.0 51.8 -11.9 305 1.5
9500 -1.6 29.1 235 13 7 7.0 3.8 10.8 51.4 -12.1 283 1.4
9250 -1.2 29.8 235 13 6 6.5 3.6 10.6 51.0 -12.4 261 1.3
9000 -0.7 30.7 235 12 6 5.9 3.2 10.3 50.5 -12.7 240 1.2
8750 -0.3 31.5 235 11 6 6.7 3.7 10.0 50.0 -13.1 219 1.1
8500 0.2 32.4 230 11 6 7.3 4.0 9.8 49.6 -13.3 196 1.0
8250 0.8 33.4 230 11 6 6.8 3.7 9.6 49.3 -13.6 174 0.9
8000 1.2 34.2 225 10 5 5.7 3.1 9.3 48.8 -13.9 153 0.8
7750 1.6 34.9 225 10 5 5.3 2.9 9.0 48.2 -14.3 134 0.7
7500 2.0 35.6 220 10 5 6.4 3.5 8.7 47.6 -14.6 114 0.6
7250 2.4 36.3 215 10 5 3.5 1.9 8.4 47.1 -15.0 94 0.5
7000 2.6 36.7 200 11 6 3.2 1.8 7.8 46.0 -15.6 83 0.4
6750 2.9 37.2 195 10 5 5.7 3.1 7.4 45.4 -16.0 64 0.3
6500 3.3 37.9 190 10 5 5.2 2.9 7.1 44.8 -16.4 46 0.2
6250 3.7 38.7 185 10 5 4.7 2.6 6.8 44.2 -16.8 27 0.1
6000 3.9 39.0 185 8 4 3.5 1.9 6.3 43.4 -17.3 12 0.1
5750 4.2 39.6 185 6 3 4.0 2.2 5.9 42.6 -17.8 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 * * * * * *

03/28/2025 at 0900 MDT | 03/28/2025 at 1200 MDT
|
CAPE... 0.0 LI... +2.6 | CAPE... +6.5 LI... +2.3
CINH... -1.1 K Index... +20.2 | CINH... -1.4 K Index... +19.5
|
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 -60.5 -76.9 255 34 18 1.1 0.6 | -59.9 -75.8 250 33 17 0.4 0.2
45000 -58.9 -74.0 250 37 19 0.5 0.3 | -59.3 -74.7 245 36 18 0.1 0.0
40000 -63.0 -81.4 250 58 30 -2.8 -1.5 | -62.9 -81.2 240 61 31 -2.4 -1.3
38000 -61.1 -78.0 250 61 32 7.4 4.1 | -60.8 -77.4 235 64 33 7.9 4.3
36000 -56.7 -70.1 245 61 31 7.4 4.1 | -56.0 -68.8 235 63 33 7.9 4.3
34000 -52.1 -61.8 245 59 31 8.3 4.6 | -51.3 -60.3 235 61 32 7.7 4.2
32000 -47.1 -52.8 245 55 28 8.3 4.6 | -46.6 -51.9 240 58 30 7.7 4.2
30000 -42.0 -43.6 240 52 27 8.9 4.9 | -41.8 -43.2 240 55 28 8.6 4.7
29000 -39.3 -38.7 240 50 26 8.9 4.9 | -39.2 -38.6 240 53 27 8.7 4.8
28000 -36.7 -34.1 240 49 25 8.9 4.9 | -36.6 -33.9 235 51 26 8.7 4.8
27000 -34.0 -29.2 235 48 25 8.4 4.6 | -34.0 -29.2 235 49 25 8.6 4.7
26000 -31.1 -24.0 235 48 25 7.8 4.3 | -31.5 -24.7 235 49 25 8.4 4.6
25000 -28.7 -19.7 230 47 24 7.9 4.3 | -28.4 -19.1 230 50 26 8.4 4.6
24000 -26.4 -15.5 230 47 24 7.3 4.0 | -26.0 -14.8 230 50 26 7.6 4.2
23000 -24.3 -11.7 230 45 23 7.1 3.9 | -23.8 -10.8 230 50 26 7.2 4.0
22000 -22.2 -8.0 230 43 22 7.1 3.9 | -21.7 -7.1 230 50 25 7.2 4.0
21000 -20.2 -4.4 230 41 21 6.6 3.6 | -19.6 -3.3 230 49 25 5.8 3.2
20000 -18.2 -0.8 230 39 20 6.7 3.7 | -17.9 -0.2 230 46 24 5.8 3.2
19500 -17.2 1.0 230 38 20 6.7 3.7 | -17.0 1.4 230 45 23 5.8 3.2
19000 -16.2 2.8 230 38 19 6.7 3.7 | -16.2 2.8 235 43 22 5.8 3.2
18500 -15.3 4.5 230 37 19 6.2 3.4 | -15.3 4.5 235 42 22 5.6 3.0
18000 -14.4 6.1 230 35 18 6.1 3.3 | -14.5 5.9 235 41 21 5.4 3.0
17500 -13.5 7.7 230 34 18 6.0 3.3 | -13.7 7.3 240 39 20 5.4 3.0
17000 -12.6 9.3 230 33 17 6.0 3.3 | -12.9 8.8 240 38 20 5.8 3.2
16500 -11.7 10.9 225 32 16 6.0 3.3 | -12.0 10.4 240 37 19 5.7 3.1
16000 -10.8 12.6 225 30 16 6.3 3.5 | -11.2 11.8 240 36 18 6.2 3.4
15500 -9.9 14.2 225 29 15 6.3 3.5 | -10.3 13.5 235 34 17 6.2 3.4
15000 -8.9 16.0 225 28 14 6.6 3.6 | -9.4 15.1 235 32 16 6.1 3.3
14500 -7.9 17.8 225 26 14 6.7 3.7 | -8.5 16.7 235 30 16 6.0 3.3
14000 -7.0 19.4 225 25 13 6.6 3.6 | -7.6 18.3 235 29 15 6.1 3.4
13500 -6.0 21.2 225 24 12 6.4 3.5 | -6.7 19.9 230 26 13 6.4 3.5
13000 -5.1 22.8 225 23 12 6.5 3.6 | -5.8 21.6 230 24 12 6.6 3.6
12500 -4.1 24.6 230 22 11 6.9 3.8 | -4.6 23.7 225 22 11 8.2 4.5
12000 -3.1 26.4 230 21 11 7.0 3.8 | -3.4 25.9 225 20 11 8.1 4.4
11500 -1.9 28.6 235 20 10 8.1 4.4 | -2.2 28.0 225 19 10 8.5 4.7
11000 -0.7 30.7 235 20 10 7.8 4.3 | -0.9 30.4 220 18 9 8.4 4.6
10500 0.3 32.5 240 18 9 6.3 3.5 | 0.2 32.4 220 17 9 7.3 4.0
10250 0.8 33.4 245 17 9 8.3 4.5 | 0.8 33.4 220 16 8 8.7 4.8
10000 1.6 34.9 240 17 9 11.5 6.3 | 1.5 34.7 220 16 8 10.9 6.0
9750 2.5 36.5 240 17 9 10.1 5.6 | 2.3 36.1 215 16 8 9.5 5.2
9500 3.1 37.6 240 17 9 8.6 4.7 | 3.0 37.4 215 15 8 8.3 4.5
9250 4.5 40.1 245 15 8 9.5 5.2 | 3.6 38.5 210 14 7 8.4 4.6
9000 5.2 41.4 235 16 8 9.3 5.1 | 4.2 39.6 210 14 7 9.3 5.1
8750 5.8 42.4 235 15 8 8.5 4.6 | 5.7 42.3 205 13 7 9.1 5.0
8500 6.5 43.7 235 15 8 8.6 4.7 | 6.4 43.5 200 13 7 9.3 5.1
8250 7.2 45.0 230 14 7 9.1 5.0 | 7.0 44.6 200 13 6 9.1 5.0
8000 7.8 46.0 235 14 7 8.1 4.5 | 7.7 45.9 195 12 6 9.5 5.2
7750 8.4 47.1 230 13 7 6.9 3.8 | 8.5 47.3 195 12 6 10.1 5.5
7500 8.9 48.0 225 12 6 7.2 3.9 | 9.2 48.6 195 12 6 9.7 5.3
7250 9.4 48.9 220 12 6 7.1 3.9 | 9.9 49.8 190 11 6 8.2 4.5
7000 10.0 50.0 220 13 7 6.7 3.7 | 10.5 50.9 190 11 6 9.4 5.2
6750 10.4 50.7 215 11 6 6.7 3.7 | 11.3 52.3 190 11 6 11.4 6.2
6500 10.9 51.6 205 10 5 6.1 3.4 | 12.1 53.8 190 11 5 10.5 5.8
6250 11.4 52.5 200 10 5 6.1 3.3 | 12.9 55.2 185 10 5 10.9 6.0
6000 11.8 53.2 200 11 6 4.0 2.2 | 13.7 56.7 180 10 5 8.7 4.8
5750 11.9 53.4 190 8 4 0.2 0.1 | 14.3 57.7 180 9 5 12.4 6.8
5500 12.3 54.1 180 5 3 17.9 9.8 | 16.7 62.1 175 8 4 65.4 35.9
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

03/28/2025 at 1500 MDT | 03/28/2025 at 1800 MDT
|
CAPE... +9.3 LI... +1.5 | CAPE... +28.8 LI... +1.0
CINH... -0.5 K Index... +21.2 | CINH... -5.7 K Index... +21.9
|
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 -59.8 -75.6 245 35 18 0.3 0.2 | -58.8 -73.8 245 35 18 1.1 0.6
45000 -59.3 -74.7 240 38 20 0.2 0.1 | -57.2 -71.0 240 43 22 1.3 0.7
40000 -61.9 -79.4 230 64 33 -1.7 -0.9 | -61.1 -78.0 225 61 31 -2.6 -1.4
38000 -60.1 -76.2 230 68 35 6.7 3.7 | -60.2 -76.4 220 64 33 5.4 3.0
36000 -56.1 -69.0 225 68 35 6.7 3.7 | -56.9 -70.4 215 64 33 5.4 3.0
34000 -51.9 -61.4 225 66 34 8.1 4.4 | -53.3 -63.9 215 64 33 9.2 5.0
32000 -47.0 -52.6 225 60 31 8.1 4.4 | -47.9 -54.2 210 59 30 9.0 4.9
30000 -42.1 -43.8 225 55 28 8.7 4.8 | -42.5 -44.5 215 54 28 8.5 4.7
29000 -39.4 -38.9 230 54 28 8.8 4.8 | -40.0 -40.0 215 52 27 8.6 4.7
28000 -36.8 -34.2 230 53 27 8.8 4.8 | -37.4 -35.3 215 49 25 8.6 4.7
27000 -34.2 -29.6 230 51 26 8.7 4.8 | -34.8 -30.6 220 47 24 8.5 4.7
26000 -31.7 -25.1 230 52 27 8.5 4.6 | -32.4 -26.3 220 46 24 8.1 4.4
25000 -28.5 -19.3 230 52 27 8.5 4.7 | -29.4 -20.9 220 45 23 8.1 4.5
24000 -26.0 -14.8 230 52 27 7.7 4.2 | -27.0 -16.6 225 44 23 7.7 4.2
23000 -23.9 -11.0 230 52 27 7.1 3.9 | -24.8 -12.6 225 43 22 7.1 3.9
22000 -21.8 -7.2 230 51 26 7.1 3.9 | -22.8 -9.0 220 43 22 7.1 3.9
21000 -19.8 -3.6 225 49 25 5.4 3.0 | -20.7 -5.3 220 42 22 6.0 3.3
20000 -18.2 -0.8 225 45 23 5.2 2.8 | -19.1 -2.4 220 39 20 5.6 3.0
19500 -17.5 0.5 225 42 22 5.2 2.9 | -18.2 -0.8 220 37 19 5.6 3.0
19000 -16.7 1.9 225 40 21 5.2 2.9 | -17.4 0.7 220 35 18 5.6 3.0
18500 -15.9 3.4 225 38 19 5.2 2.9 | -16.6 2.1 220 34 17 5.5 3.0
18000 -15.2 4.6 225 34 18 5.2 2.8 | -15.8 3.6 220 32 16 5.3 2.9
17500 -14.4 6.1 225 31 16 5.2 2.8 | -15.0 5.0 220 29 15 5.2 2.9
17000 -13.6 7.5 225 29 15 6.3 3.5 | -14.2 6.4 215 28 14 6.2 3.4
16500 -12.6 9.3 225 26 14 6.2 3.4 | -13.3 8.1 215 26 14 6.1 3.3
16000 -11.7 10.9 225 24 12 6.4 3.5 | -12.4 9.7 215 25 13 6.5 3.6
15500 -10.8 12.6 220 23 12 6.4 3.5 | -11.4 11.5 215 25 13 6.7 3.7
15000 -9.8 14.4 220 22 11 6.6 3.6 | -10.4 13.3 215 25 13 6.8 3.7
14500 -8.8 16.2 220 21 11 6.9 3.8 | -9.4 15.1 215 25 13 6.8 3.8
14000 -7.8 18.0 220 20 10 6.9 3.8 | -8.4 16.9 215 25 13 6.8 3.8
13500 -6.8 19.8 220 20 10 7.1 3.9 | -7.4 18.7 215 24 13 6.7 3.7
13000 -5.8 21.6 220 19 10 7.1 3.9 | -6.4 20.5 215 24 12 6.7 3.7
12500 -4.6 23.7 220 19 10 8.4 4.6 | -5.4 22.3 215 24 12 7.6 4.2
12000 -3.4 25.9 220 18 9 8.3 4.5 | -4.3 24.3 215 23 12 7.5 4.1
11500 -2.0 28.4 220 18 9 9.6 5.3 | -3.2 26.2 215 23 12 7.8 4.3
11000 -0.6 30.9 215 18 9 9.5 5.2 | -2.0 28.4 220 23 12 7.9 4.3
10500 0.8 33.4 215 18 9 8.6 4.7 | -1.0 30.2 220 22 11 6.6 3.6
10250 1.4 34.5 215 17 9 9.8 5.4 | -0.4 31.3 220 22 11 7.6 4.2
10000 2.3 36.1 215 18 9 11.6 6.4 | 0.2 32.4 220 22 11 10.1 5.6
9750 3.1 37.6 215 18 9 10.7 5.8 | 1.0 33.8 220 21 11 9.3 5.1
9500 3.9 39.0 215 18 9 9.7 5.3 | 1.6 34.9 220 21 11 7.9 4.3
9250 4.6 40.3 215 18 9 10.0 5.5 | 2.2 36.0 220 21 11 7.7 4.2
9000 6.1 43.0 210 18 9 9.8 5.4 | 3.6 38.5 220 20 10 10.8 5.9
8750 6.8 44.2 210 18 9 9.9 5.5 | 4.3 39.7 220 19 10 8.8 4.8
8500 7.6 45.7 210 18 9 9.7 5.3 | 5.0 41.0 220 19 10 9.7 5.3
8250 8.3 46.9 210 18 9 10.6 5.8 | 5.7 42.3 220 18 9 8.3 4.5
8000 9.1 48.4 210 18 9 10.4 5.7 | 6.2 43.2 220 18 9 8.7 4.8
7750 9.8 49.6 210 18 9 9.4 5.2 | 7.0 44.6 220 17 9 10.0 5.5
7500 10.6 51.1 210 18 9 9.7 5.3 | 7.7 45.9 220 16 8 10.1 5.6
7250 11.3 52.3 210 17 9 9.1 5.0 | 8.4 47.1 220 15 8 7.5 4.1
7000 12.0 53.6 210 18 9 9.6 5.3 | 8.9 48.0 220 15 8 8.2 4.5
6750 12.7 54.9 210 17 9 10.4 5.7 | 9.7 49.5 220 14 7 11.3 6.2
6500 13.5 56.3 210 17 9 10.4 5.7 | 10.5 50.9 220 13 6 10.2 5.6
6250 14.3 57.7 210 17 9 12.2 6.7 | 11.2 52.2 220 12 6 10.2 5.6
6000 15.2 59.4 205 17 9 8.7 4.8 | 12.0 53.6 220 12 6 9.0 4.9
5750 15.7 60.3 210 16 8 9.6 5.2 | 12.6 54.7 220 10 5 9.7 5.3
5500 18.1 64.6 205 14 7 72.8 40.0 | 13.8 56.8 215 8 4 27.1 14.9
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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