Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
028
UXUS97 KGJT 221307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Sunday, September 22, 2024
This forecast is for Sunday, September 22, 2024:
If the trigger temperature of 64.0 F/17.8 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 689 ft/min (3.5 m/s)
Maximum height of thermals.................. 13975 ft MSL (9136 ft AGL)
Forecast maximum temperature................... 76.0 F/24.9 C
Time of trigger temperature.................... 1045 MDT
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................. 11282 ft MSL (6442 ft AGL)
Thermal soaring outlook for Monday 09/23....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:02:38 / 19:10:33 MDT
Total possible sunshine........... 12 hr 7 min 55 sec (727 min 55 sec)
Altitude of sun at 13:06:36 MDT... 50.75 degrees
Upper air data from rawinsonde observation taken on 09/22/2024 at 0600 MDT
Freezing level.................. 12281 ft MSL (7442 ft AGL)
Convective condensation level... 10607 ft MSL (5768 ft AGL)
Lifted condensation level....... 12447 ft MSL (7607 ft AGL)
Lifted index.................... -0.6
K index......................... +22.4
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 -59.3 -74.7 265 29 15 3.3 1.8 97.8 208.0 42.3 M M
45000 -54.4 -65.9 275 31 16 3.7 2.0 81.5 178.8 35.2 M M
40000 -49.7 -57.5 280 25 13 -0.3 -0.2 65.7 150.3 27.2 M M
38000 -50.8 -59.4 330 6 3 -4.4 -2.4 54.2 129.6 20.2 M M
36000 -51.1 -60.0 360 27 14 4.7 2.6 45.4 113.8 14.6 M M
34000 -47.5 -53.5 005 14 7 7.5 4.1 42.1 107.8 12.7 M M
32000 -42.2 -44.0 005 15 8 9.5 5.2 41.5 106.7 12.5 M M
30000 -36.4 -33.5 010 16 8 7.7 4.2 41.4 106.6 12.8 M M
29000 -33.6 -28.5 025 17 9 9.9 5.4 41.3 106.3 12.8 M M
28000 -30.9 -23.6 030 16 8 7.0 3.8 41.0 105.7 12.7 M M
27000 -28.7 -19.7 025 17 9 8.8 4.8 40.0 104.1 12.1 M M
26000 -26.0 -14.8 010 16 8 9.9 5.4 39.8 103.6 12.0 M M
25000 -23.2 -9.8 025 18 9 7.3 4.0 39.6 103.2 12.0 M M
24000 -21.3 -6.3 030 17 9 7.6 4.2 38.5 101.2 11.2 M M
23000 -19.2 -2.6 020 17 9 6.1 3.4 37.4 99.4 10.4 M M
22000 -16.9 1.6 050 14 7 8.4 4.6 36.6 98.0 9.9 M M
21000 -14.4 6.1 045 15 8 7.3 4.0 36.2 97.1 9.5 M M
20000 -12.3 9.9 030 14 7 8.9 4.9 34.5 94.1 8.2 M M
19500 -11.4 11.5 025 13 7 3.2 1.8 33.8 92.9 7.6 M M
19000 -10.8 12.6 015 13 7 4.5 2.5 32.8 91.0 6.8 M M
18500 -10.1 13.8 020 14 7 4.9 2.7 31.9 89.5 6.1 M M
18000 -9.3 15.3 025 15 8 5.6 3.1 31.1 88.0 5.4 M M
17500 -8.4 16.9 015 13 7 6.6 3.6 30.5 87.0 4.9 M M
17000 -7.4 18.7 015 14 7 6.7 3.7 30.1 86.1 4.4 M M
16500 -6.5 20.3 360 17 9 6.1 3.3 29.4 85.0 3.9 M M
16000 -5.7 21.7 360 19 10 4.7 2.6 28.7 83.7 3.3 M M
15500 -5.1 22.8 005 20 10 4.5 2.5 27.8 82.1 2.4 M M
15000 -4.4 24.1 015 21 11 4.5 2.5 27.0 80.5 1.6 M M
14500 -3.8 25.2 010 20 10 4.6 2.5 26.1 78.9 0.8 M M
14000 -3.2 26.2 005 22 11 5.2 2.9 25.2 77.4 -0.0 688 3.5
13500 -2.3 27.9 010 21 11 6.4 3.5 24.6 76.3 -0.6 646 3.3
13000 -1.3 29.7 020 20 10 6.4 3.5 24.1 75.3 -1.1 603 3.1
12500 -0.4 31.3 020 20 10 6.4 3.5 23.5 74.3 -1.6 560 2.8
12000 0.6 33.1 010 19 10 6.4 3.5 23.0 73.3 -2.2 518 2.6
11500 1.5 34.7 015 16 8 6.2 3.4 22.4 72.3 -2.7 475 2.4
11000 2.2 36.0 025 12 6 4.4 2.4 21.7 71.0 -3.5 438 2.2
10500 2.9 37.2 040 8 4 4.7 2.6 20.8 69.5 -4.3 404 2.1
10250 3.2 37.8 060 7 4 4.0 2.2 20.4 68.8 -4.7 387 2.0
10000 3.5 38.3 120 6 3 5.4 3.0 20.0 68.0 -5.2 370 1.9
9750 4.0 39.2 125 6 3 7.1 3.9 19.7 67.5 -5.4 348 1.8
9500 4.5 40.1 125 6 3 6.6 3.6 19.5 67.1 -5.7 326 1.7
9250 5.0 41.0 115 6 3 6.8 3.7 19.3 66.7 -5.9 304 1.5
9000 5.4 41.7 120 6 3 6.7 3.6 19.0 66.3 -6.2 282 1.4
8750 5.9 42.6 140 5 3 7.1 3.9 18.8 65.8 -6.4 260 1.3
8500 6.4 43.5 145 7 3 5.3 2.9 18.6 65.4 -6.7 238 1.2
8250 6.7 44.1 140 8 4 3.3 1.8 18.1 64.6 -7.2 224 1.1
8000 6.9 44.4 135 10 5 4.6 2.5 17.6 63.7 -7.7 209 1.1
7750 7.3 45.1 135 12 6 6.3 3.5 17.3 63.1 -8.1 190 1.0
7500 7.8 46.0 145 14 7 6.8 3.8 17.1 62.7 -8.4 168 0.9
7250 8.2 46.8 145 16 8 6.7 3.7 16.8 62.3 -8.6 146 0.7
7000 8.7 47.7 140 16 8 6.7 3.7 16.6 61.9 -8.9 124 0.6
6750 9.2 48.6 140 16 8 6.7 3.7 16.4 61.5 -9.2 102 0.5
6500 9.7 49.5 140 15 8 6.8 3.7 16.1 61.1 -9.4 80 0.4
6250 10.2 50.4 140 16 8 7.4 4.1 15.9 60.7 -9.7 58 0.3
6000 10.8 51.4 145 15 8 7.5 4.1 15.8 60.4 -9.9 34 0.2
5750 11.3 52.3 145 14 7 8.0 4.4 15.6 60.1 -10.1 10 0.0
5500 11.8 53.2 145 13 6 2.2 1.2 15.4 59.7 -10.4 M M
5250 11.7 53.1 135 11 6 -3.4 -1.8 14.5 58.1 -11.2 M M
5000 11.6 52.9 110 10 5 5.1 2.8 13.7 56.7 -12.1 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
09/22/2024 at 0900 MDT | 09/22/2024 at 1200 MDT
|
CAPE... 0.0 LI... +2.2 | CAPE... +9.8 LI... +2.3
CINH... -0.3 K Index... +21.8 | CINH... -4.3 K Index... +22.0
|
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 -58.6 -73.5 285 21 11 2.3 1.3 | -58.7 -73.7 285 19 10 2.7 1.5
45000 -54.7 -66.5 285 26 13 2.9 1.6 | -54.7 -66.5 285 23 12 2.4 1.3
40000 -50.4 -58.7 280 26 13 2.8 1.5 | -51.1 -60.0 275 22 11 2.3 1.2
38000 -50.3 -58.5 290 16 8 -0.1 -0.1 | -50.7 -59.3 270 13 7 0.4 0.2
36000 -50.4 -58.7 335 7 3 -0.1 -0.1 | -50.5 -58.9 230 4 2 0.3 0.2
34000 -47.4 -53.3 025 7 4 8.3 4.6 | -47.3 -53.1 175 2 1 8.3 4.5
32000 -42.4 -44.3 020 7 4 8.3 4.6 | -42.3 -44.1 335 1 1 8.3 4.5
30000 -37.1 -34.8 010 9 4 9.0 4.9 | -37.2 -35.0 350 5 2 8.7 4.8
29000 -34.4 -29.9 005 10 5 9.0 5.0 | -34.7 -30.5 355 7 3 8.7 4.8
28000 -31.8 -25.2 005 12 6 9.1 5.0 | -32.1 -25.8 355 9 4 8.7 4.8
27000 -29.2 -20.6 360 13 7 8.1 4.5 | -29.6 -21.3 360 10 5 8.3 4.5
26000 -26.8 -16.2 005 15 8 8.1 4.5 | -27.1 -16.8 360 12 6 8.3 4.5
25000 -24.4 -11.9 005 16 8 8.1 4.5 | -24.6 -12.3 005 14 7 8.3 4.5
24000 -22.1 -7.8 360 17 9 7.2 3.9 | -22.3 -8.1 005 15 8 7.6 4.1
23000 -19.9 -3.8 360 17 9 7.2 4.0 | -20.0 -4.0 010 17 9 7.6 4.2
22000 -17.8 -0.0 360 16 8 7.2 4.0 | -17.2 1.0 010 18 9 7.7 4.2
21000 -15.4 4.3 360 16 8 6.3 3.4 | -15.1 4.8 010 18 9 6.9 3.8
20000 -13.5 7.7 005 15 8 6.3 3.5 | -13.1 8.4 010 17 9 6.9 3.8
19500 -12.6 9.3 005 15 8 6.3 3.5 | -12.1 10.2 015 17 9 7.0 3.8
19000 -11.7 10.9 005 14 7 6.2 3.4 | -11.1 12.0 015 16 8 6.4 3.5
18500 -10.8 12.6 010 14 7 6.1 3.3 | -10.2 13.6 015 15 8 6.1 3.3
18000 -9.9 14.2 010 15 8 6.1 3.3 | -9.3 15.3 015 14 7 6.1 3.3
17500 -9.0 15.8 010 15 8 6.1 3.4 | -8.5 16.7 020 13 7 5.4 3.0
17000 -8.1 17.4 015 15 8 6.2 3.4 | -7.7 18.1 020 13 6 5.5 3.0
16500 -7.2 19.0 015 15 8 5.8 3.2 | -7.0 19.4 020 12 6 5.1 2.8
16000 -6.4 20.5 015 15 8 5.6 3.1 | -6.2 20.8 020 11 6 5.0 2.8
15500 -5.6 21.9 015 15 8 5.6 3.0 | -5.5 22.1 025 10 5 5.0 2.7
15000 -4.9 23.2 015 15 8 5.4 2.9 | -4.8 23.4 030 10 5 4.8 2.6
14500 -4.1 24.6 015 15 8 5.4 3.0 | -4.1 24.6 035 10 5 4.9 2.7
14000 -3.3 26.1 015 15 7 5.2 2.9 | -3.4 25.9 035 9 5 5.7 3.1
13500 -2.6 27.3 015 14 7 5.3 2.9 | -2.6 27.3 040 9 5 5.7 3.1
13000 -1.9 28.6 015 14 7 4.9 2.7 | -1.8 28.8 045 9 5 5.5 3.0
12500 -1.2 29.8 015 13 7 4.9 2.7 | -1.0 30.2 045 8 4 5.5 3.0
12000 -0.4 31.3 015 12 6 5.9 3.2 | -0.2 31.6 045 7 4 5.6 3.1
11500 0.4 32.7 015 11 5 5.9 3.2 | 0.6 33.1 050 6 3 5.4 3.0
11000 1.3 34.3 020 9 5 6.1 3.3 | 1.5 34.7 050 5 3 7.2 4.0
10500 2.1 35.8 025 8 4 6.3 3.5 | 2.6 36.7 050 4 2 7.6 4.2
10250 2.6 36.7 030 7 4 5.2 2.8 | 3.1 37.6 050 4 2 6.0 3.3
10000 2.9 37.2 030 7 3 5.8 3.2 | 3.5 38.3 055 4 2 6.7 3.7
9750 3.4 38.1 040 6 3 7.4 4.1 | 4.1 39.4 055 3 2 8.7 4.8
9500 4.0 39.2 050 5 2 7.0 3.8 | 4.7 40.5 060 3 2 8.4 4.6
9250 4.5 40.1 060 4 2 7.1 3.9 | 5.3 41.5 060 3 1 7.6 4.2
9000 5.0 41.0 070 4 2 6.6 3.6 | 5.8 42.4 070 2 1 7.5 4.1
8750 5.4 41.7 080 4 2 6.2 3.4 | 6.4 43.5 070 2 1 8.5 4.7
8500 5.9 42.6 095 4 2 6.2 3.4 | 7.0 44.6 075 2 1 8.3 4.5
8250 6.4 43.5 110 4 2 6.0 3.3 | 8.0 46.4 085 2 1 6.5 3.6
8000 6.8 44.2 120 4 2 5.9 3.2 | 8.6 47.5 090 1 1 10.5 5.8
7750 7.7 45.9 125 5 2 6.4 3.5 | 9.4 48.9 095 1 1 10.0 5.5
7500 8.2 46.8 130 5 3 5.3 2.9 | 10.0 50.0 095 1 1 7.0 3.8
7250 8.5 47.3 130 5 3 4.9 2.7 | 10.5 50.9 100 1 1 6.7 3.7
7000 9.0 48.2 130 6 3 7.1 3.9 | 11.2 52.2 100 1 1 12.3 6.8
6750 9.5 49.1 130 5 3 7.0 3.8 | 12.2 54.0 095 1 1 12.6 6.9
6500 9.9 49.8 130 5 3 5.5 3.0 | 12.9 55.2 100 1 1 9.1 5.0
6250 10.3 50.5 135 6 3 5.2 2.8 | 13.6 56.5 105 1 1 9.0 4.9
6000 10.7 51.3 135 6 3 8.5 4.7 | 14.4 57.9 105 1 1 13.2 7.3
5750 11.6 52.9 130 5 2 16.5 9.1 | 15.8 60.4 105 1 1 25.9 14.2
5500 12.5 54.5 130 5 2 0.7 0.4 | 17.5 63.5 105 1 1 11.9 6.5
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
09/22/2024 at 1500 MDT | 09/22/2024 at 1800 MDT
|
CAPE... +3.1 LI... +1.3 | CAPE... +6.3 LI... +0.7
CINH... -1.1 K Index... +21.8 | CINH... -22.4 K Index... +21.6
|
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 -59.0 -74.2 280 17 9 2.8 1.6 | -58.7 -73.7 280 20 10 3.0 1.6
45000 -54.8 -66.6 280 19 10 1.8 1.0 | -54.5 -66.1 280 21 11 1.3 0.7
40000 -52.2 -62.0 275 20 11 1.7 0.9 | -52.5 -62.5 285 16 8 1.3 0.7
38000 -51.5 -60.7 270 15 8 1.0 0.6 | -51.7 -61.1 290 13 7 1.3 0.7
36000 -50.9 -59.6 255 11 5 1.0 0.6 | -51.0 -59.8 295 10 5 1.3 0.7
34000 -47.4 -53.3 250 7 4 8.5 4.6 | -47.5 -53.5 305 8 4 8.2 4.5
32000 -42.3 -44.1 265 5 3 8.4 4.6 | -42.6 -44.7 320 8 4 8.2 4.5
30000 -37.2 -35.0 300 5 2 8.6 4.7 | -37.5 -35.5 325 8 4 8.7 4.8
29000 -34.6 -30.3 320 5 3 8.7 4.7 | -34.9 -30.8 325 9 5 8.7 4.8
28000 -32.0 -25.6 330 6 3 8.7 4.8 | -32.3 -26.1 325 10 5 8.7 4.8
27000 -29.4 -20.9 340 7 4 8.6 4.7 | -29.7 -21.5 330 10 5 8.7 4.8
26000 -26.9 -16.4 350 9 4 8.6 4.7 | -27.1 -16.8 330 9 5 8.7 4.8
25000 -24.3 -11.7 355 10 5 8.6 4.7 | -24.5 -12.1 335 9 5 8.7 4.8
24000 -21.9 -7.4 005 11 6 7.6 4.2 | -22.1 -7.8 345 9 4 7.5 4.1
23000 -19.6 -3.3 010 12 6 7.6 4.2 | -19.8 -3.6 355 9 4 7.5 4.1
22000 -16.8 1.8 015 13 7 7.8 4.3 | -17.1 1.2 005 9 5 7.7 4.2
21000 -14.8 5.4 020 13 7 6.3 3.5 | -15.1 4.8 015 9 5 6.2 3.4
20000 -13.0 8.6 020 13 7 6.4 3.5 | -13.3 8.1 025 9 5 6.3 3.5
19500 -12.1 10.2 025 13 7 6.4 3.5 | -12.4 9.7 030 9 5 6.3 3.5
19000 -11.1 12.0 025 13 7 5.9 3.3 | -11.5 11.3 035 10 5 6.2 3.4
18500 -10.3 13.5 030 12 6 5.8 3.2 | -10.6 12.9 035 9 5 6.1 3.4
18000 -9.5 14.9 030 12 6 5.8 3.2 | -9.7 14.5 040 9 5 6.1 3.4
17500 -8.7 16.3 035 11 6 5.8 3.2 | -8.8 16.2 040 9 5 6.3 3.5
17000 -7.8 18.0 040 10 5 5.8 3.2 | -7.9 17.8 045 9 5 6.3 3.4
16500 -7.0 19.4 045 10 5 5.9 3.3 | -7.0 19.4 045 9 4 6.7 3.7
16000 -6.1 21.0 050 9 5 6.0 3.3 | -6.0 21.2 045 8 4 6.8 3.7
15500 -5.2 22.6 060 9 5 6.0 3.3 | -5.0 23.0 045 8 4 7.0 3.8
15000 -4.4 24.1 060 8 4 5.9 3.3 | -3.9 25.0 045 8 4 7.3 4.0
14500 -3.5 25.7 065 7 4 6.0 3.3 | -2.9 26.8 045 7 4 7.3 4.0
14000 -2.6 27.3 065 7 3 6.3 3.5 | -1.8 28.8 040 7 4 6.9 3.8
13500 -1.8 28.8 060 6 3 6.3 3.4 | -0.8 30.6 040 7 3 6.9 3.8
13000 -0.8 30.6 060 5 3 6.6 3.6 | 0.2 32.4 035 6 3 7.5 4.1
12500 0.1 32.2 055 4 2 6.5 3.6 | 1.3 34.3 035 6 3 7.5 4.1
12000 1.1 34.0 055 4 2 7.3 4.0 | 2.4 36.3 030 5 3 7.9 4.3
11500 2.1 35.8 055 3 2 7.3 4.0 | 3.5 38.3 030 5 2 7.9 4.3
11000 3.2 37.8 050 3 2 7.9 4.3 | 4.7 40.5 030 4 2 7.8 4.3
10500 4.4 39.9 050 3 1 8.3 4.5 | 5.8 42.4 035 4 2 7.5 4.1
10250 4.9 40.8 045 3 1 6.4 3.5 | 6.4 43.5 035 4 2 9.3 5.1
10000 5.4 41.7 045 3 1 7.4 4.0 | 7.1 44.8 035 3 2 9.5 5.2
9750 6.1 43.0 040 3 1 9.9 5.4 | 7.8 46.0 035 3 2 8.0 4.4
9500 6.8 44.2 035 3 1 9.5 5.2 | 8.4 47.1 040 3 2 8.3 4.5
9250 7.5 45.5 030 3 1 8.5 4.6 | 9.0 48.2 040 3 1 8.6 4.7
9000 8.0 46.4 030 2 1 8.3 4.5 | 9.6 49.3 050 3 1 9.1 5.0
8750 8.7 47.7 030 2 1 9.3 5.1 | 10.3 50.5 050 2 1 8.8 4.8
8500 9.4 48.9 025 2 1 9.2 5.0 | 11.0 51.8 050 2 1 9.2 5.0
8250 10.5 50.9 025 2 1 7.7 4.2 | 12.1 53.8 075 1 1 7.4 4.1
8000 11.2 52.2 025 1 1 11.2 6.1 | 12.7 54.9 090 1 1 9.9 5.4
7750 12.0 53.6 025 1 1 10.7 5.9 | 13.5 56.3 100 1 0 9.7 5.3
7500 12.7 54.9 025 1 1 8.3 4.6 | 14.1 57.4 115 1 0 7.8 4.3
7250 13.3 55.9 025 1 1 7.9 4.3 | 14.7 58.5 135 1 1 7.3 4.0
7000 14.0 57.2 025 1 1 12.3 6.7 | 15.3 59.5 145 1 1 10.4 5.7
6750 15.0 59.0 020 1 1 12.4 6.8 | 16.1 61.0 145 1 0 11.2 6.1
6500 15.8 60.4 020 1 0 9.7 5.3 | 16.9 62.4 150 1 1 9.7 5.3
6250 16.5 61.7 020 1 0 9.7 5.3 | 17.6 63.7 160 1 1 9.8 5.4
6000 17.3 63.1 025 1 0 11.8 6.5 | 18.3 64.9 165 1 1 9.4 5.2
5750 18.5 65.3 020 1 0 21.8 12.0 | 19.0 66.2 165 1 1 11.5 6.3
5500 20.4 68.7 000 0 0 27.0 14.8 | 20.3 68.5 170 2 1 23.6 13.0
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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