Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
626
UXUS97 KGJT 041306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Wednesday, December 4, 2024
This forecast is for Wednesday, December 4, 2024:
If the trigger temperature of 60.6 F/15.9 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 271 ft/min (1.4 m/s)
Maximum height of thermals.................. 7584 ft MSL (2745 ft AGL)
Forecast maximum temperature................... 51.0 F/11.0 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................. 6372 ft MSL (1533 ft AGL)
Thermal soaring outlook for Thursday 12/05..... Poor
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:17:58 / 16:51:21 MST
Total possible sunshine........... 9 hr 33 min 22 sec (573 min 22 sec)
Altitude of sun at 12:04:39 MST... 28.50 degrees
Upper air data from rawinsonde observation taken on 12/04/2024 at 0500 MST
Freezing level.................. 4954 ft MSL (115 ft AGL)
Additional freezing level....... 10841 ft MSL (6002 ft AGL)
Convective condensation level... 16882 ft MSL (12043 ft AGL)
Lifted condensation level....... 12347 ft MSL (7507 ft AGL)
Lifted index.................... +9.7
K index......................... -2.0
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 -59.1 -74.4 270 21 11 -2.6 -1.4 103.8 218.9 53.0 M M
45000 -60.3 -76.5 265 14 7 -1.7 -0.9 77.0 170.6 40.4 M M
40000 -58.6 -73.5 330 3 2 -5.0 -2.8 56.4 133.4 29.8 M M
38000 -59.2 -74.6 050 14 7 -1.4 -0.8 45.5 113.9 23.5 M M
36000 -57.5 -71.5 060 23 12 1.5 0.8 39.3 102.7 19.8 M M
34000 -54.4 -65.9 050 27 14 8.5 4.7 35.3 95.5 17.5 M M
32000 -49.6 -57.3 070 37 19 4.8 2.6 33.9 92.9 17.0 M M
30000 -44.6 -48.3 075 35 18 8.8 4.8 32.7 90.9 16.5 M M
29000 -41.9 -43.4 065 26 13 8.7 4.8 32.3 90.1 16.5 M M
28000 -39.3 -38.7 060 23 12 8.7 4.8 31.9 89.4 16.4 M M
27000 -36.7 -34.1 065 21 11 8.6 4.7 31.5 88.7 16.2 M M
26000 -34.1 -29.4 075 22 12 8.5 4.6 31.1 87.9 16.1 M M
25000 -32.0 -25.6 080 19 10 7.3 4.0 30.0 86.1 15.5 M M
24000 -30.1 -22.2 075 27 14 7.0 3.8 28.8 83.8 14.7 M M
23000 -27.5 -17.5 070 28 14 8.6 4.7 28.4 83.1 14.5 M M
22000 -24.9 -12.8 070 27 14 8.6 4.7 28.0 82.4 14.4 M M
21000 -22.5 -8.5 075 25 13 6.2 3.4 27.3 81.2 14.0 M M
20000 -20.1 -4.2 065 16 8 6.3 3.4 25.8 78.5 12.9 M M
19500 -19.0 -2.2 055 16 8 8.9 4.9 25.5 77.8 12.6 M M
19000 -17.6 0.3 050 15 8 7.2 4.0 25.3 77.6 12.6 M M
18500 -17.0 1.4 055 10 5 3.2 1.8 24.4 75.9 11.8 M M
18000 -16.5 2.3 070 12 6 6.6 3.6 23.3 74.0 10.9 M M
17500 -15.2 4.6 065 9 5 8.1 4.4 23.1 73.5 10.8 M M
17000 -14.0 6.8 060 8 4 8.2 4.5 22.8 73.1 10.6 M M
16500 -12.8 9.0 050 9 5 8.2 4.5 22.6 72.6 10.5 M M
16000 -11.5 11.3 045 8 4 8.2 4.5 22.3 72.1 10.3 M M
15500 -10.3 13.5 050 7 4 8.3 4.5 22.0 71.6 10.1 M M
15000 -9.1 15.6 070 6 3 7.7 4.2 21.7 71.1 9.9 M M
14500 -7.9 17.8 090 8 4 7.4 4.1 21.4 70.5 9.6 M M
14000 -6.9 19.6 085 8 4 7.1 3.9 21.0 69.7 9.3 M M
13500 -5.8 21.6 090 9 5 8.1 4.5 20.5 68.9 9.0 M M
13000 -4.5 23.9 080 9 5 8.8 4.8 20.4 68.7 8.9 M M
12500 -3.2 26.2 075 9 5 8.9 4.9 20.2 68.4 8.8 M M
12000 -1.9 28.6 065 7 4 6.5 3.6 20.0 68.0 8.6 M M
11500 -1.1 30.0 060 7 4 5.8 3.2 19.3 66.8 8.0 M M
11000 -0.3 31.5 075 5 3 5.5 3.0 18.7 65.6 7.4 M M
10500 0.7 33.3 040 3 2 7.9 4.4 18.2 64.7 6.9 M M
10250 1.3 34.3 015 3 2 7.3 4.0 18.0 64.4 6.8 M M
10000 1.8 35.2 015 3 2 6.6 3.6 17.8 64.0 6.6 M M
9750 2.3 36.1 360 2 1 6.3 3.4 17.5 63.6 6.4 M M
9500 2.7 36.9 015 1 1 6.0 3.3 17.2 63.0 6.1 M M
9250 3.2 37.8 045 2 1 6.5 3.6 17.0 62.5 5.8 M M
9000 3.6 38.5 055 4 2 4.7 2.6 16.7 62.0 5.6 M M
8750 3.8 38.8 070 5 2 0.8 0.4 16.1 61.0 5.0 M M
8500 3.8 38.8 080 5 3 1.1 0.6 15.4 59.7 4.3 M M
8250 3.8 38.8 080 6 3 -2.2 -1.2 14.7 58.4 3.6 M M
8000 3.4 38.1 085 5 3 -6.8 -3.7 13.5 56.3 2.4 M M
7750 2.8 37.0 090 6 3 -8.8 -4.9 12.1 53.9 1.1 M M
7500 2.2 36.0 085 7 4 -2.3 -1.3 10.8 51.5 -0.2 272 1.4
7250 2.5 36.5 080 9 5 4.7 2.6 10.3 50.5 -0.7 258 1.3
7000 2.7 36.9 080 11 6 3.5 1.9 9.8 49.7 -1.1 243 1.2
6750 3.0 37.4 080 11 6 3.5 1.9 9.4 48.8 -1.6 227 1.2
6500 3.1 37.6 080 11 5 -0.9 -0.5 8.8 47.8 -2.2 216 1.1
6250 2.9 37.2 075 10 5 -4.9 -2.7 7.7 45.9 -3.2 216 1.1
6000 2.6 36.7 110 8 4 -0.5 -0.3 6.7 44.1 -4.2 217 1.1
5750 2.8 37.0 130 9 5 5.4 3.0 6.2 43.2 -4.8 204 1.0
5500 3.0 37.4 140 14 7 -5.5 -3.0 5.6 42.2 -5.4 192 1.0
5250 1.9 35.4 130 13 7 -17.1 -9.4 3.9 39.0 -7.1 215 1.1
5000 0.8 33.4 135 14 7 -11.2 -6.1 2.0 35.7 -9.0 241 1.2
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
12/04/2024 at 0800 MST | 12/04/2024 at 1100 MST
|
CAPE... 0.0 LI... +4.9 | CAPE... 0.0 LI... +5.1
CINH... 0.0 K Index... -0.3 | CINH... -0.1 K Index... -1.0
|
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 -61.0 -77.8 285 21 11 0.9 0.5 | -61.2 -78.2 290 21 11 0.5 0.3
45000 -59.7 -75.5 290 15 8 -0.1 -0.1 | -60.5 -76.9 305 13 7 -0.0 -0.0
40000 -60.6 -77.1 055 17 9 -0.6 -0.3 | -60.8 -77.4 075 20 11 -0.2 -0.1
38000 -59.6 -75.3 065 27 14 3.5 1.9 | -59.5 -75.1 075 31 16 4.0 2.2
36000 -57.2 -71.0 070 38 20 3.5 1.9 | -56.9 -70.4 075 41 21 4.0 2.2
34000 -54.2 -65.6 070 44 23 7.8 4.3 | -53.7 -64.7 075 45 23 7.7 4.2
32000 -49.5 -57.1 080 43 22 7.9 4.3 | -49.1 -56.4 080 40 21 7.7 4.2
30000 -44.7 -48.5 080 40 21 8.6 4.7 | -44.3 -47.7 080 35 18 8.2 4.5
29000 -42.1 -43.8 080 37 19 8.6 4.7 | -41.9 -43.4 080 33 17 8.2 4.5
28000 -39.5 -39.1 080 34 18 8.6 4.7 | -39.4 -38.9 080 30 16 8.2 4.5
27000 -37.0 -34.6 080 32 16 8.5 4.7 | -36.9 -34.4 080 28 15 8.5 4.6
26000 -34.4 -29.9 075 30 16 8.5 4.7 | -34.4 -29.9 080 27 14 8.4 4.6
25000 -31.9 -25.4 070 29 15 8.5 4.7 | -31.9 -25.4 075 26 14 8.4 4.6
24000 -29.4 -20.9 065 28 14 7.9 4.3 | -29.4 -20.9 075 26 13 8.1 4.5
23000 -27.0 -16.6 065 27 14 7.8 4.3 | -26.4 -15.5 070 26 14 8.1 4.4
22000 -24.1 -11.4 060 26 13 7.7 4.3 | -24.0 -11.2 065 27 14 8.1 4.4
21000 -21.9 -7.4 055 25 13 7.1 3.9 | -21.7 -7.1 065 26 13 7.4 4.1
20000 -19.8 -3.6 060 22 11 7.1 3.9 | -19.5 -3.1 065 23 12 7.4 4.0
19500 -18.7 -1.7 060 21 11 7.1 3.9 | -18.4 -1.1 065 22 11 7.4 4.0
19000 -17.7 0.1 060 20 10 7.0 3.8 | -17.3 0.9 065 21 11 7.2 3.9
18500 -16.7 1.9 060 19 10 6.7 3.7 | -16.2 2.8 065 19 10 6.8 3.7
18000 -15.7 3.7 060 17 9 6.6 3.6 | -15.2 4.6 065 17 9 6.8 3.8
17500 -14.7 5.5 060 16 8 7.1 3.9 | -14.2 6.4 065 16 8 6.7 3.7
17000 -13.6 7.5 060 14 7 7.1 3.9 | -13.2 8.2 065 14 7 6.7 3.7
16500 -12.6 9.3 055 13 7 7.1 3.9 | -12.2 10.0 065 13 7 6.9 3.8
16000 -11.5 11.3 055 12 6 7.2 3.9 | -11.1 12.0 065 12 6 7.0 3.8
15500 -10.4 13.3 055 11 6 7.2 4.0 | -10.1 13.8 065 11 6 7.0 3.9
15000 -9.3 15.3 055 11 5 7.5 4.1 | -9.0 15.8 060 10 5 7.2 3.9
14500 -8.2 17.2 055 10 5 7.5 4.1 | -8.0 17.6 055 9 5 7.2 3.9
14000 -7.1 19.2 050 10 5 7.4 4.1 | -6.9 19.6 050 9 5 7.3 4.0
13500 -6.0 21.2 050 10 5 7.4 4.1 | -5.8 21.6 045 9 5 7.3 4.0
13000 -5.0 23.0 050 9 5 7.4 4.1 | -4.8 23.4 045 9 5 7.3 4.0
12500 -3.9 25.0 050 9 5 7.5 4.1 | -3.7 25.3 040 9 5 7.4 4.0
12000 -2.8 27.0 050 9 5 7.0 3.8 | -2.6 27.3 040 9 5 7.1 3.9
11500 -1.8 28.8 050 9 5 7.0 3.8 | -1.6 29.1 040 9 5 7.1 3.9
11000 -0.8 30.6 045 9 5 6.5 3.6 | -0.6 30.9 040 9 5 6.6 3.6
10500 0.2 32.4 045 9 5 6.8 3.8 | 0.4 32.7 040 9 5 7.0 3.8
10250 0.6 33.1 045 9 4 5.0 2.7 | 0.9 33.6 040 9 5 5.4 3.0
10000 0.9 33.6 050 9 4 3.9 2.1 | 1.2 34.2 040 9 5 4.7 2.6
9750 1.3 34.3 050 8 4 5.1 2.8 | 1.6 34.9 040 9 5 5.8 3.2
9500 1.6 34.9 050 8 4 5.1 2.8 | 2.0 35.6 040 9 5 5.6 3.1
9250 2.0 35.6 050 7 4 4.2 2.3 | 2.4 36.3 040 9 4 4.9 2.7
9000 2.2 36.0 050 7 4 3.0 1.7 | 2.7 36.9 045 9 4 3.6 2.0
8750 2.4 36.3 055 7 4 2.5 1.4 | 3.0 37.4 045 8 4 2.4 1.3
8500 2.6 36.7 055 7 3 2.0 1.1 | 3.1 37.6 045 8 4 1.8 1.0
8250 2.8 37.0 060 6 3 1.5 0.8 | 3.4 38.1 050 7 3 2.2 1.2
8000 2.9 37.2 065 6 3 0.6 0.4 | 3.5 38.3 050 6 3 1.4 0.8
7750 2.9 37.2 070 5 3 0.2 0.1 | 3.6 38.5 055 5 3 0.5 0.3
7500 2.9 37.2 075 5 2 0.8 0.4 | 3.6 38.5 060 5 3 0.8 0.4
7250 3.0 37.4 080 4 2 1.0 0.5 | 3.6 38.5 060 4 2 0.2 0.1
7000 3.0 37.4 090 4 2 -0.1 -0.1 | 3.7 38.7 065 4 2 2.3 1.2
6750 3.0 37.4 090 4 2 -0.2 -0.1 | 3.9 39.0 065 4 2 4.1 2.3
6500 3.0 37.4 090 4 2 0.5 0.3 | 4.2 39.6 070 3 2 4.2 2.3
6250 3.0 37.4 095 4 2 1.3 0.7 | 4.5 40.1 075 2 1 1.9 1.1
6000 3.0 37.4 100 4 2 -8.0 -4.4 | 4.6 40.3 085 2 1 5.0 2.8
5750 1.6 34.9 095 4 2 -26.7 -14.6 | 5.4 41.7 090 2 1 17.8 9.8
5500 0.3 32.5 095 3 2 6.9 3.8 | 6.3 43.3 100 2 1 -4.9 -2.7
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
12/04/2024 at 1400 MST | 12/04/2024 at 1700 MST
|
CAPE... 0.0 LI... +5.3 | CAPE... 0.0 LI... +5.6
CINH... -0.2 K Index... -2.0 | CINH... -0.0 K Index... -2.1
|
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 -61.5 -78.7 290 18 9 0.5 0.3 | -61.5 -78.7 285 19 10 0.7 0.4
45000 -60.7 -77.3 310 10 5 -0.4 -0.2 | -60.4 -76.7 300 8 4 -1.1 -0.6
40000 -61.9 -79.4 080 22 12 -0.8 -0.4 | -62.7 -80.9 085 27 14 -1.6 -0.9
38000 -60.3 -76.5 080 31 16 5.4 3.0 | -60.8 -77.4 085 34 17 6.4 3.5
36000 -56.6 -69.9 080 39 20 5.4 3.0 | -56.5 -69.7 080 37 19 6.4 3.5
34000 -53.0 -63.4 075 42 21 7.4 4.1 | -52.5 -62.5 080 37 19 7.3 4.0
32000 -48.6 -55.5 075 36 18 7.4 4.0 | -48.1 -54.6 070 33 17 7.3 4.0
30000 -44.0 -47.2 070 31 16 8.2 4.5 | -43.6 -46.5 065 29 15 7.8 4.3
29000 -41.5 -42.7 075 29 15 8.2 4.5 | -41.2 -42.2 065 27 14 7.8 4.3
28000 -39.0 -38.2 075 27 14 8.2 4.5 | -38.9 -38.0 065 25 13 7.8 4.3
27000 -36.6 -33.9 075 25 13 8.3 4.6 | -36.5 -33.7 065 23 12 8.4 4.6
26000 -34.1 -29.4 075 24 12 8.3 4.6 | -34.0 -29.2 065 23 12 8.3 4.6
25000 -31.6 -24.9 075 23 12 8.3 4.6 | -31.5 -24.7 065 22 11 8.3 4.6
24000 -29.1 -20.4 075 22 11 8.2 4.5 | -29.0 -20.2 065 22 11 8.2 4.5
23000 -26.7 -16.1 075 22 11 8.2 4.5 | -26.6 -15.9 065 22 11 8.2 4.5
22000 -23.6 -10.5 075 22 11 8.2 4.5 | -23.6 -10.5 070 22 11 8.2 4.5
21000 -21.3 -6.3 075 21 11 7.4 4.0 | -21.2 -6.2 070 21 11 7.7 4.2
20000 -19.2 -2.6 075 19 10 7.4 4.0 | -18.9 -2.0 075 19 10 7.7 4.2
19500 -18.1 -0.6 075 18 10 7.4 4.0 | -17.8 -0.0 075 19 10 7.7 4.2
19000 -17.0 1.4 080 18 9 7.3 4.0 | -16.6 2.1 075 18 9 7.5 4.1
18500 -15.9 3.4 075 16 8 7.0 3.9 | -15.6 3.9 075 17 9 7.1 3.9
18000 -14.9 5.2 075 15 8 7.0 3.9 | -14.5 5.9 075 15 8 7.2 3.9
17500 -13.8 7.2 075 13 7 6.8 3.7 | -13.5 7.7 075 14 7 6.9 3.8
17000 -12.8 9.0 075 12 6 6.8 3.7 | -12.4 9.7 070 13 6 6.9 3.8
16500 -11.8 10.8 070 10 5 6.7 3.7 | -11.4 11.5 070 11 6 6.8 3.7
16000 -10.8 12.6 065 9 5 6.6 3.6 | -10.4 13.3 065 10 5 6.7 3.6
15500 -9.8 14.4 065 8 4 6.7 3.7 | -9.4 15.1 060 9 5 6.6 3.6
15000 -8.8 16.2 060 8 4 7.1 3.9 | -8.4 16.9 060 8 4 6.7 3.7
14500 -7.7 18.1 055 7 4 7.1 3.9 | -7.4 18.7 055 7 4 6.7 3.6
14000 -6.7 19.9 050 7 4 7.1 3.9 | -6.4 20.5 050 7 4 6.9 3.8
13500 -5.6 21.9 045 7 4 7.1 3.9 | -5.4 22.3 045 7 3 6.9 3.8
13000 -4.6 23.7 040 7 4 7.2 3.9 | -4.3 24.3 045 7 3 7.0 3.8
12500 -3.5 25.7 035 7 4 7.2 3.9 | -3.3 26.1 045 7 3 7.0 3.9
12000 -2.5 27.5 035 8 4 7.3 4.0 | -2.3 27.9 045 7 4 6.9 3.8
11500 -1.4 29.5 035 8 4 7.3 4.0 | -1.3 29.7 045 7 4 7.0 3.8
11000 -0.4 31.3 035 8 4 6.8 3.7 | -0.3 31.5 045 7 4 6.7 3.7
10500 0.6 33.1 040 8 4 7.1 3.9 | 0.7 33.3 045 7 4 7.0 3.8
10250 1.1 34.0 040 8 4 5.5 3.0 | 1.2 34.2 045 7 4 5.5 3.0
10000 1.5 34.7 040 8 4 5.2 2.8 | 1.5 34.7 045 7 4 5.1 2.8
9750 1.9 35.4 040 8 4 6.4 3.5 | 2.0 35.6 050 7 4 6.4 3.5
9500 2.4 36.3 040 8 4 6.2 3.4 | 2.4 36.3 050 7 4 6.1 3.4
9250 2.8 37.0 045 8 4 5.4 3.0 | 2.9 37.2 050 7 4 5.8 3.2
9000 3.2 37.8 045 8 4 4.2 2.3 | 3.3 37.9 050 7 4 5.0 2.8
8750 3.5 38.3 045 8 4 4.0 2.2 | 3.6 38.5 045 7 4 4.6 2.5
8500 3.7 38.7 045 7 4 3.7 2.1 | 3.9 39.0 045 7 3 4.2 2.3
8250 4.3 39.7 050 7 4 3.4 1.9 | 4.5 40.1 045 6 3 3.5 1.9
8000 4.5 40.1 050 7 3 2.6 1.4 | 4.8 40.6 045 6 3 3.6 2.0
7750 4.6 40.3 045 6 3 1.9 1.0 | 5.0 41.0 045 6 3 3.3 1.8
7500 4.8 40.6 050 5 3 2.2 1.2 | 5.2 41.4 045 5 3 2.9 1.6
7250 4.9 40.8 050 5 2 1.5 0.8 | 5.4 41.7 045 5 2 3.1 1.7
7000 5.0 41.0 055 4 2 4.1 2.2 | 5.6 42.1 045 4 2 2.4 1.3
6750 5.5 41.9 050 3 2 6.9 3.8 | 5.8 42.4 040 3 2 3.5 1.9
6500 5.9 42.6 050 3 1 6.7 3.7 | 6.1 43.0 040 3 1 4.3 2.4
6250 6.4 43.5 055 2 1 6.0 3.3 | 6.4 43.5 035 2 1 5.9 3.2
6000 6.9 44.4 060 2 1 8.8 4.8 | 6.7 44.1 035 1 1 -0.3 -0.2
5750 7.8 46.0 065 2 1 15.6 8.6 | 6.0 42.8 045 1 1 -17.6 -9.7
5500 8.7 47.7 070 1 1 3.1 1.7 | 5.1 41.2 000 0 0 6.2 3.4
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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