Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
153
UXUS97 KGJT 101307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Friday, May 10, 2024
This forecast is for Friday, May 10, 2024:
If the trigger temperature of 55.7 F/13.2 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 691 ft/min (3.5 m/s)
Maximum height of thermals.................. 17354 ft MSL (12515 ft AGL)
Forecast maximum temperature................... 68.0 F/20.5 C
Time of trigger temperature.................... 0900 MDT
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................. 12301 ft MSL (7462 ft AGL)
Thermal soaring outlook for Saturday 05/11..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:04:55 / 20:16:08 MDT
Total possible sunshine........... 14 hr 11 min 12 sec (851 min 12 sec)
Altitude of sun at 13:10:32 MDT... 68.66 degrees
Upper air data from rawinsonde observation taken on 05/10/2024 at 0600 MDT
Freezing level.................. 9391 ft MSL (4552 ft AGL)
Convective condensation level... 12321 ft MSL (7482 ft AGL)
Lifted condensation level....... 13691 ft MSL (8852 ft AGL)
Lifted index.................... -3.8
K index......................... +21.9
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 -53.8 -64.8 235 14 7 -2.6 -1.5 110.4 230.7 51.7 M M
45000 -50.9 -59.6 235 27 14 -4.5 -2.5 90.5 194.9 43.1 M M
40000 -52.7 -62.9 250 33 17 0.2 0.1 64.5 148.1 29.1 M M
38000 -50.2 -58.4 230 38 20 4.5 2.5 59.5 139.0 26.5 M M
36000 -47.3 -53.1 250 37 19 4.1 2.2 54.0 129.2 23.5 M M
34000 -45.8 -50.4 235 59 30 3.6 2.0 47.8 118.1 19.7 M M
32000 -43.3 -45.9 225 38 20 4.5 2.5 43.1 109.5 16.8 M M
30000 -41.9 -43.4 225 35 18 3.8 2.1 37.1 98.8 12.7 M M
29000 -41.7 -43.1 205 20 10 -1.5 -0.8 33.4 92.2 10.1 M M
28000 -41.3 -42.3 190 21 11 1.6 0.9 30.1 86.2 7.7 M M
27000 -41.7 -43.1 195 25 13 0.8 0.4 25.7 78.3 4.4 M M
26000 -39.6 -39.3 175 14 7 8.9 4.9 24.7 76.5 3.7 M M
25000 -36.9 -34.4 175 17 9 9.0 4.9 24.4 76.0 3.5 M M
24000 -34.2 -29.6 175 16 8 9.0 5.0 24.1 75.4 3.3 M M
23000 -31.4 -24.5 195 19 10 9.2 5.0 23.9 75.0 3.1 M M
22000 -28.9 -20.0 195 21 11 6.4 3.5 23.4 74.1 2.8 M M
21000 -26.5 -15.7 200 19 10 8.2 4.5 22.8 73.0 2.3 M M
20000 -24.4 -11.9 205 19 10 8.4 4.6 21.8 71.2 1.5 M M
19500 -23.1 -9.6 205 19 10 8.9 4.9 21.7 71.0 1.3 M M
19000 -21.1 -6.0 200 19 10 8.9 4.9 21.5 70.6 1.2 M M
18500 -19.7 -3.5 205 17 9 9.8 5.4 21.4 70.5 1.1 M M
18000 -18.6 -1.5 210 16 8 5.1 2.8 20.9 69.7 0.7 M M
17500 -17.8 -0.0 210 16 8 5.5 3.0 20.2 68.4 0.1 M M
17000 -17.0 1.4 195 14 7 5.4 2.9 19.5 67.1 -0.6 1056 5.4
16500 -16.0 3.2 185 12 6 8.7 4.7 19.0 66.2 -1.1 1011 5.1
16000 -14.7 5.5 160 9 5 8.8 4.8 18.8 65.9 -1.3 958 4.9
15500 -13.4 7.9 165 9 5 8.8 4.8 18.7 65.6 -1.4 904 4.6
15000 -12.2 10.0 170 10 5 9.1 5.0 18.5 65.3 -1.6 851 4.3
14500 -10.8 12.6 165 11 6 9.8 5.4 18.5 65.2 -1.7 794 4.0
14000 -9.5 14.9 175 14 7 6.0 3.3 18.2 64.8 -1.9 743 3.8
13500 -8.5 16.7 180 15 8 8.1 4.5 17.7 63.9 -2.4 698 3.5
13000 -7.3 18.9 185 17 9 8.4 4.6 17.5 63.5 -2.6 646 3.3
12500 -6.0 21.2 180 20 10 8.2 4.5 17.3 63.1 -2.9 593 3.0
12000 -5.0 23.0 170 20 10 6.7 3.7 16.9 62.4 -3.3 547 2.8
11500 -4.0 24.8 160 17 9 6.9 3.8 16.4 61.5 -3.8 504 2.6
11000 -2.9 26.8 150 15 8 8.0 4.4 16.1 60.9 -4.2 455 2.3
10500 -1.8 28.8 130 13 7 2.5 1.4 15.8 60.4 -4.5 406 2.1
10250 -1.8 28.8 125 13 7 0.7 0.4 14.9 58.9 -5.4 401 2.0
10000 -1.5 29.3 110 10 5 8.0 4.4 14.6 58.3 -5.7 382 1.9
9750 -0.9 30.4 110 10 5 7.8 4.3 14.5 58.0 -5.9 357 1.8
9500 -0.3 31.5 110 8 4 7.6 4.2 14.3 57.7 -6.0 333 1.7
9250 0.3 32.5 115 7 4 7.7 4.2 14.1 57.4 -6.2 308 1.6
9000 0.8 33.4 110 7 4 7.6 4.2 14.0 57.1 -6.4 284 1.4
8750 1.4 34.5 105 8 4 7.7 4.2 13.8 56.8 -6.6 259 1.3
8500 2.0 35.6 105 8 4 7.7 4.2 13.6 56.5 -6.8 235 1.2
8250 2.5 36.5 100 9 4 7.7 4.2 13.5 56.2 -6.9 211 1.1
8000 3.1 37.6 095 9 5 7.7 4.2 13.3 56.0 -7.1 186 0.9
7750 3.7 38.7 100 9 4 7.6 4.2 13.1 55.7 -7.3 162 0.8
7500 4.2 39.6 120 8 4 8.0 4.4 13.0 55.4 -7.5 138 0.7
7250 4.8 40.6 125 9 5 8.3 4.6 12.9 55.2 -7.6 112 0.6
7000 5.5 41.9 135 10 5 8.2 4.5 12.8 55.0 -7.8 86 0.4
6750 6.1 43.0 135 10 5 8.3 4.5 12.6 54.8 -7.9 60 0.3
6500 6.7 44.1 145 11 6 8.2 4.5 12.5 54.6 -8.0 35 0.2
6250 7.3 45.1 150 12 6 8.3 4.5 12.4 54.4 -8.2 9 0.0
6000 7.9 46.2 160 11 6 8.1 4.5 12.3 54.1 -8.3 M M
5750 8.5 47.3 160 11 5 8.7 4.8 12.2 53.9 -8.5 M M
5500 9.1 48.4 155 10 5 6.4 3.5 12.1 53.7 -8.6 M M
5250 9.5 49.1 145 9 5 5.9 3.2 11.7 53.1 -9.0 M M
5000 9.7 49.5 140 10 5 -1.6 -0.9 11.3 52.4 -9.5 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/10/2024 at 0900 MDT | 05/10/2024 at 1200 MDT
|
CAPE... +52.4 LI... -0.2 | CAPE... +171.1 LI... -1.0
CINH... -32.3 K Index... +17.9 | CINH... -8.7 K Index... +22.3
|
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 -53.9 -65.0 245 13 7 1.8 1.0 | -54.0 -65.2 250 18 9 1.5 0.8
45000 -51.4 -60.5 255 14 7 0.2 0.1 | -51.8 -61.2 240 18 9 0.9 0.5
40000 -50.9 -59.6 245 23 12 0.3 0.2 | -50.4 -58.7 230 25 13 0.9 0.5
38000 -49.8 -57.6 240 31 16 2.5 1.4 | -49.5 -57.1 230 31 16 1.8 1.0
36000 -48.4 -55.1 235 39 20 2.5 1.4 | -48.4 -55.1 230 38 20 1.8 1.0
34000 -46.6 -51.9 235 45 23 4.1 2.3 | -47.0 -52.6 230 43 22 3.5 1.9
32000 -44.2 -47.6 230 40 21 4.1 2.3 | -44.9 -48.8 230 41 21 3.6 2.0
30000 -41.8 -43.2 225 35 18 2.8 1.5 | -42.7 -44.9 225 38 20 3.8 2.1
29000 -41.0 -41.8 215 31 16 2.9 1.6 | -41.6 -42.9 220 36 18 3.8 2.1
28000 -40.1 -40.2 210 27 14 2.9 1.6 | -40.4 -40.7 210 34 17 3.8 2.1
27000 -39.3 -38.7 195 24 13 3.4 1.9 | -39.3 -38.7 200 33 17 4.6 2.5
26000 -37.7 -35.9 195 22 11 5.4 2.9 | -37.5 -35.5 190 32 16 6.2 3.4
25000 -36.1 -33.0 190 20 10 5.4 2.9 | -35.6 -32.1 185 32 16 6.3 3.4
24000 -34.5 -30.1 185 18 9 5.4 3.0 | -33.7 -28.7 175 32 16 6.5 3.6
23000 -31.7 -25.1 180 17 9 8.1 4.4 | -30.8 -23.4 175 29 15 8.3 4.5
22000 -29.3 -20.7 180 17 9 8.1 4.4 | -28.3 -18.9 180 27 14 8.3 4.5
21000 -26.8 -16.2 180 16 8 8.3 4.6 | -25.9 -14.6 185 24 12 7.4 4.0
20000 -24.3 -11.7 180 17 9 8.3 4.6 | -23.7 -10.7 190 20 10 7.5 4.1
19500 -23.1 -9.6 185 17 9 8.3 4.6 | -22.6 -8.7 190 19 10 7.5 4.1
19000 -21.9 -7.4 185 18 9 8.4 4.6 | -21.5 -6.7 195 17 9 7.4 4.1
18500 -20.6 -5.1 185 18 9 8.0 4.4 | -20.3 -4.5 195 16 8 7.7 4.2
18000 -19.4 -2.9 185 18 9 8.1 4.4 | -19.2 -2.6 195 15 8 7.7 4.2
17500 -18.3 -0.9 185 18 9 8.0 4.4 | -18.1 -0.6 195 14 7 7.7 4.2
17000 -17.1 1.2 190 19 10 8.0 4.4 | -16.9 1.6 195 14 7 7.7 4.2
16500 -15.9 3.4 190 19 10 8.0 4.4 | -15.8 3.6 195 13 7 7.8 4.3
16000 -14.7 5.5 190 19 10 7.9 4.3 | -14.6 5.7 195 13 7 8.0 4.4
15500 -13.6 7.5 190 20 10 7.9 4.3 | -13.5 7.7 195 12 6 8.0 4.4
15000 -12.4 9.7 190 20 10 7.5 4.1 | -12.3 9.9 195 12 6 8.0 4.4
14500 -11.3 11.7 190 19 10 7.6 4.1 | -11.1 12.0 195 11 6 8.0 4.4
14000 -10.2 13.6 190 19 10 7.8 4.3 | -10.0 14.0 190 11 6 8.1 4.4
13500 -9.0 15.8 190 18 9 7.9 4.3 | -8.8 16.2 190 10 5 8.1 4.4
13000 -7.9 17.8 185 17 9 8.0 4.4 | -7.6 18.3 185 9 5 8.1 4.5
12500 -6.7 19.9 185 16 8 8.0 4.4 | -6.4 20.5 180 9 4 8.2 4.5
12000 -5.6 21.9 180 15 8 7.9 4.3 | -5.2 22.6 175 8 4 8.4 4.6
11500 -4.4 24.1 175 14 7 7.9 4.3 | -4.0 24.8 170 7 4 8.5 4.7
11000 -3.3 26.1 170 13 7 7.8 4.3 | -2.7 27.1 165 7 4 8.7 4.8
10500 -2.2 28.0 165 12 6 8.0 4.4 | -1.4 29.5 160 7 3 9.5 5.2
10250 -1.6 29.1 165 12 6 7.2 3.9 | -0.8 30.6 155 7 3 6.2 3.4
10000 -1.1 30.0 165 12 6 7.2 3.9 | -0.4 31.3 155 7 4 7.1 3.9
9750 -0.5 31.1 160 11 6 8.0 4.4 | 0.4 32.7 150 7 4 10.9 6.0
9500 0.1 32.2 160 11 6 7.6 4.2 | 1.1 34.0 150 7 4 10.1 5.6
9250 0.6 33.1 155 10 5 8.4 4.6 | 1.9 35.4 145 7 3 9.5 5.2
9000 1.3 34.3 150 10 5 8.4 4.6 | 2.5 36.5 145 7 4 8.5 4.6
8750 1.8 35.2 150 10 5 6.9 3.8 | 3.2 37.8 145 7 4 8.7 4.8
8500 2.3 36.1 145 9 5 6.6 3.6 | 3.8 38.8 140 7 4 9.1 5.0
8250 3.2 37.8 140 9 5 5.6 3.1 | 5.0 41.0 140 8 4 6.6 3.6
8000 3.7 38.7 135 9 4 7.8 4.3 | 5.5 41.9 140 9 4 8.8 4.8
7750 4.3 39.7 135 7 4 8.0 4.4 | 6.2 43.2 145 9 4 9.2 5.0
7500 4.7 40.5 130 6 3 5.2 2.8 | 6.8 44.2 145 9 5 7.7 4.2
7250 5.0 41.0 125 5 3 3.1 1.7 | 7.4 45.3 145 9 5 6.9 3.8
7000 5.4 41.7 120 5 2 9.1 5.0 | 7.9 46.2 145 9 5 9.6 5.2
6750 6.3 43.3 110 4 2 11.8 6.5 | 8.7 47.7 145 9 4 11.3 6.2
6500 7.0 44.6 110 3 2 8.9 4.9 | 9.5 49.1 145 8 4 10.8 5.9
6250 7.7 45.9 105 3 2 9.0 4.9 | 10.3 50.5 145 8 4 10.2 5.6
6000 8.4 47.1 100 3 2 11.5 6.3 | 11.1 52.0 150 8 4 12.8 7.0
5750 9.5 49.1 105 3 2 19.8 10.9 | 12.4 54.3 145 7 4 23.7 13.0
5500 10.9 51.6 100 3 2 12.0 6.6 | 14.5 58.1 145 7 3 30.8 16.9
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
05/10/2024 at 1500 MDT | 05/10/2024 at 1800 MDT
|
CAPE... +178.4 LI... -0.1 | CAPE... +109.4 LI... -0.5
CINH... -3.0 K Index... +21.5 | CINH... -12.9 K Index... +20.9
|
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 -54.1 -65.4 255 22 11 1.4 0.7 | -54.2 -65.6 260 21 11 1.4 0.7
45000 -52.1 -61.8 245 25 13 1.0 0.6 | -52.2 -62.0 250 25 13 0.8 0.5
40000 -50.5 -58.9 235 32 16 1.1 0.6 | -50.9 -59.6 240 30 15 0.9 0.5
38000 -49.7 -57.5 235 37 19 1.3 0.7 | -50.0 -58.0 235 36 18 1.6 0.9
36000 -48.9 -56.0 230 43 22 1.3 0.7 | -49.0 -56.2 230 43 22 1.6 0.9
34000 -47.9 -54.2 230 47 24 2.9 1.6 | -48.0 -54.4 225 47 24 2.0 1.1
32000 -46.1 -51.0 230 47 24 2.9 1.6 | -46.8 -52.2 230 44 23 2.0 1.1
30000 -44.1 -47.4 225 43 22 5.1 2.8 | -45.0 -49.0 230 39 20 6.4 3.5
29000 -42.5 -44.5 220 37 19 5.2 2.8 | -43.1 -45.6 225 35 18 6.5 3.6
28000 -41.0 -41.8 210 32 16 5.2 2.8 | -41.1 -42.0 220 30 16 6.5 3.6
27000 -39.5 -39.1 200 28 14 6.5 3.6 | -39.2 -38.6 210 26 14 7.4 4.0
26000 -37.1 -34.8 195 25 13 7.9 4.3 | -36.7 -34.1 210 22 11 8.1 4.5
25000 -34.7 -30.5 185 22 12 7.9 4.4 | -34.3 -29.7 205 18 9 8.1 4.5
24000 -32.4 -26.3 175 21 11 8.0 4.4 | -31.9 -25.4 200 15 7 8.1 4.5
23000 -29.3 -20.7 175 19 10 8.3 4.6 | -28.8 -19.8 195 13 7 8.2 4.5
22000 -26.8 -16.2 170 19 10 8.4 4.6 | -26.4 -15.5 190 13 7 8.2 4.5
21000 -24.4 -11.9 170 18 9 7.6 4.2 | -24.0 -11.2 185 13 6 7.8 4.3
20000 -22.1 -7.8 175 16 8 7.7 4.2 | -21.7 -7.1 180 13 7 7.8 4.3
19500 -21.0 -5.8 180 16 8 7.7 4.2 | -20.5 -4.9 180 14 7 7.9 4.3
19000 -19.8 -3.6 180 15 8 7.7 4.2 | -19.3 -2.7 180 14 7 7.9 4.3
18500 -18.7 -1.7 180 14 7 7.3 4.0 | -18.2 -0.8 180 14 7 7.6 4.2
18000 -17.6 0.3 180 13 7 7.3 4.0 | -17.1 1.2 180 14 7 7.7 4.2
17500 -16.5 2.3 180 13 7 7.4 4.1 | -15.9 3.4 185 14 7 7.6 4.2
17000 -15.4 4.3 180 12 6 7.4 4.1 | -14.8 5.4 185 14 7 7.5 4.1
16500 -14.3 6.3 180 12 6 7.4 4.1 | -13.7 7.3 190 14 7 7.5 4.1
16000 -13.3 8.1 180 11 6 7.4 4.0 | -12.6 9.3 190 13 7 7.6 4.2
15500 -12.2 10.0 180 11 6 7.4 4.1 | -11.5 11.3 195 13 7 7.6 4.2
15000 -11.1 12.0 180 11 6 7.4 4.1 | -10.4 13.3 195 12 6 7.6 4.2
14500 -10.0 14.0 175 10 5 7.4 4.1 | -9.3 15.3 195 12 6 7.6 4.2
14000 -8.9 16.0 175 10 5 7.5 4.1 | -8.2 17.2 195 11 6 7.6 4.2
13500 -7.8 18.0 175 10 5 7.5 4.1 | -7.1 19.2 195 10 5 7.6 4.2
13000 -6.7 19.9 175 9 5 7.6 4.1 | -6.0 21.2 190 9 4 7.6 4.1
12500 -5.6 21.9 170 9 4 7.6 4.2 | -4.9 23.2 185 7 4 7.6 4.1
12000 -4.5 23.9 165 8 4 7.7 4.2 | -3.8 25.2 180 6 3 7.4 4.1
11500 -3.4 25.9 160 7 4 7.8 4.3 | -2.7 27.1 170 6 3 7.3 4.0
11000 -2.2 28.0 155 7 4 8.1 4.4 | -1.6 29.1 155 5 2 7.5 4.1
10500 -1.0 30.2 145 7 3 8.7 4.8 | -0.5 31.1 140 4 2 7.9 4.3
10250 -0.4 31.3 140 6 3 5.9 3.2 | 0.1 32.2 130 4 2 6.7 3.7
10000 -0.1 31.8 130 7 3 6.3 3.4 | 0.5 32.9 130 5 2 6.9 3.8
9750 0.5 32.9 130 6 3 9.3 5.1 | 1.1 34.0 115 5 2 8.3 4.6
9500 1.2 34.2 130 6 3 8.6 4.7 | 1.7 35.1 105 4 2 7.9 4.3
9250 1.8 35.2 130 6 3 8.6 4.7 | 2.3 36.1 090 5 2 8.2 4.5
9000 2.4 36.3 130 7 3 8.4 4.6 | 2.9 37.2 095 5 3 7.8 4.3
8750 3.0 37.4 130 7 3 8.3 4.6 | 3.4 38.1 090 5 3 6.9 3.8
8500 3.7 38.7 130 6 3 8.6 4.7 | 4.4 39.9 070 5 3 6.9 3.8
8250 4.8 40.6 135 6 3 6.6 3.6 | 4.9 40.8 070 5 3 7.2 4.0
8000 5.3 41.5 135 6 3 8.8 4.8 | 5.5 41.9 070 5 3 8.8 4.8
7750 6.0 42.8 135 6 3 9.1 5.0 | 6.1 43.0 065 5 3 9.4 5.1
7500 6.6 43.9 140 6 3 6.5 3.6 | 6.8 44.2 060 5 3 8.0 4.4
7250 7.0 44.6 145 7 4 4.8 2.7 | 7.3 45.1 060 6 3 6.9 3.8
7000 7.4 45.3 150 8 4 9.2 5.1 | 7.9 46.2 060 6 3 10.7 5.9
6750 8.2 46.8 145 6 3 10.4 5.7 | 8.8 47.8 060 5 3 11.8 6.5
6500 8.9 48.0 150 6 3 7.9 4.3 | 9.6 49.3 055 6 3 9.3 5.1
6250 9.4 48.9 155 7 4 7.5 4.1 | 10.3 50.5 055 6 3 9.1 5.0
6000 10.0 50.0 160 7 4 11.0 6.0 | 10.9 51.6 055 6 3 10.6 5.8
5750 11.2 52.2 155 5 3 22.2 12.2 | 11.9 53.4 055 5 2 16.5 9.1
5500 12.8 55.0 160 6 3 16.6 9.1 | 13.3 55.9 055 5 3 20.0 11.0
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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