Soaring Guidance Issued by NWS Grand Junction, CO
000
UXUS97 KGJT 281307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Thursday, March 28, 2024
This forecast is for Thursday, March 28, 2024:
If the trigger temperature of 52.3 F/11.3 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 523 ft/min (2.7 m/s)
Maximum height of thermals.................. 14072 ft MSL (9233 ft AGL)
Forecast maximum temperature................... 63.0 F/17.7 C
Time of trigger temperature.................... 1115 MDT
Time of overdevelopment........................ 1300 MDT
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 12687 ft MSL (7848 ft AGL)
Thermal soaring outlook for Friday 03/29....... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:03:32 / 19:34:20 MDT
Total possible sunshine........... 12 hr 30 min 48 sec (750 min 48 sec)
Altitude of sun at 13:18:56 MDT... 54.03 degrees
Upper air data from rawinsonde observation taken on 03/28/2024 at 0600 MDT
Freezing level.................. 8440 ft MSL (3601 ft AGL)
Convective condensation level... 18803 ft MSL (13964 ft AGL)
Lifted condensation level....... 16915 ft MSL (12076 ft AGL)
Lifted index.................... +4.6
K index......................... -7.3
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 -57.9 -72.2 250 56 29 1.6 0.9 107.8 226.0 51.2 M M
45000 -60.6 -77.1 265 61 31 -6.1 -3.4 78.2 172.8 36.9 M M
40000 -60.8 -77.4 265 81 42 -14.1 -7.7 54.5 130.1 24.2 M M
38000 -64.7 -84.5 270 80 41 4.6 2.5 38.4 101.1 14.2 M M
36000 -60.8 -77.4 265 87 45 6.4 3.5 35.5 95.9 12.6 M M
34000 -55.8 -68.4 265 85 44 8.5 4.6 34.3 93.7 12.1 M M
32000 -50.9 -59.6 265 76 39 8.8 4.8 32.9 91.3 11.4 M M
30000 -45.9 -50.6 265 71 37 8.5 4.7 31.9 89.3 10.9 M M
29000 -43.3 -45.9 265 73 37 8.6 4.7 31.4 88.5 10.7 M M
28000 -40.9 -41.6 265 67 35 7.8 4.3 30.7 87.2 10.3 M M
27000 -38.6 -37.5 270 62 32 7.7 4.2 29.9 85.8 9.8 M M
26000 -36.1 -33.0 265 54 28 7.8 4.3 29.4 84.9 9.5 M M
25000 -33.7 -28.7 270 53 27 8.1 4.4 28.7 83.7 9.1 M M
24000 -31.7 -25.1 265 52 27 8.6 4.7 27.6 81.6 8.2 M M
23000 -29.7 -21.5 260 51 26 6.4 3.5 26.4 79.5 7.4 M M
22000 -27.6 -17.7 265 48 25 7.4 4.1 25.5 77.9 6.7 M M
21000 -25.3 -13.5 265 49 25 7.3 4.0 24.6 76.3 6.1 M M
20000 -22.3 -8.1 265 41 21 8.3 4.5 23.9 75.0 5.5 M M
19500 -21.1 -6.0 260 39 20 8.2 4.5 23.6 74.5 5.3 M M
19000 -19.9 -3.8 260 42 22 8.1 4.4 23.3 74.0 5.1 M M
18500 -18.6 -1.5 260 39 20 7.5 4.1 23.1 73.6 4.9 M M
18000 -17.7 0.1 255 37 19 5.7 3.1 22.4 72.4 4.3 M M
17500 -16.7 1.9 255 37 19 8.8 4.8 22.0 71.5 3.9 M M
17000 -15.6 3.9 255 33 17 6.1 3.4 21.6 70.8 3.6 M M
16500 -14.7 5.5 255 31 16 6.3 3.5 21.0 69.7 3.0 M M
16000 -13.5 7.7 255 27 14 7.3 4.0 20.4 68.8 2.8 M M
15500 -12.6 9.3 245 24 12 4.7 2.6 19.9 67.8 2.3 M M
15000 -11.9 10.6 225 28 14 4.4 2.4 19.0 66.1 1.5 M M
14500 -11.3 11.7 235 26 13 4.4 2.4 18.1 64.5 0.7 M M
14000 -10.7 12.7 230 26 13 4.4 2.4 17.2 62.9 -0.2 715 3.6
13500 -10.0 14.0 225 28 14 3.5 1.9 16.3 61.3 -1.1 682 3.5
13000 -10.1 13.8 235 31 16 0.9 0.5 14.7 58.5 -2.6 668 3.4
12500 -9.1 15.6 240 30 15 8.4 4.6 14.1 57.4 -3.1 625 3.2
12000 -7.9 17.8 240 29 15 8.2 4.5 13.9 57.0 -3.4 574 2.9
11500 -6.7 19.9 240 26 13 8.2 4.5 13.6 56.5 -3.6 522 2.7
11000 -5.5 22.1 245 23 12 8.2 4.5 13.4 56.1 -3.9 471 2.4
10500 -4.2 24.4 240 20 10 8.2 4.5 13.1 55.6 -4.2 419 2.1
10250 -3.6 25.5 235 18 9 8.3 4.5 13.0 55.4 -4.3 393 2.0
10000 -3.0 26.6 235 18 9 7.0 3.9 12.8 55.1 -4.4 368 1.9
9750 -2.6 27.3 245 18 9 6.0 3.3 12.6 54.6 -4.7 347 1.8
9500 -2.1 28.2 235 18 9 6.3 3.5 12.3 54.1 -5.0 325 1.7
9250 -1.6 29.1 235 18 10 6.2 3.4 12.0 53.7 -5.2 304 1.5
9000 -1.1 30.0 235 19 10 6.2 3.4 11.8 53.2 -5.5 282 1.4
8750 -0.7 30.7 240 17 9 6.2 3.4 11.5 52.7 -5.8 260 1.3
8500 -0.2 31.6 235 18 9 6.2 3.4 11.2 52.2 -6.1 239 1.2
8250 0.3 32.5 230 21 11 6.2 3.4 10.9 51.7 -6.3 217 1.1
8000 0.8 33.4 220 20 10 6.2 3.4 10.7 51.2 -6.6 196 1.0
7750 1.2 34.2 210 19 10 6.2 3.4 10.4 50.7 -6.9 174 0.9
7500 1.7 35.1 195 18 9 6.3 3.4 10.1 50.2 -7.2 152 0.8
7250 2.2 36.0 175 19 10 6.2 3.4 9.8 49.7 -7.4 131 0.7
7000 2.7 36.9 165 21 11 6.3 3.4 9.6 49.2 -7.7 109 0.6
6750 3.1 37.6 160 22 12 6.8 3.8 9.3 48.8 -8.0 87 0.4
6500 3.7 38.7 155 24 12 7.3 4.0 9.1 48.4 -8.2 64 0.3
6250 4.2 39.6 155 25 13 7.1 3.9 8.9 48.1 -8.4 41 0.2
6000 4.7 40.5 145 24 12 7.6 4.2 8.7 47.7 -8.7 18 0.1
5750 5.2 41.4 145 24 12 5.8 3.2 8.5 47.4 -8.9 M M
5500 5.2 41.4 145 22 12 -10.8 -5.9 7.8 46.0 -9.7 M M
5250 4.0 39.2 145 24 12 -9.6 -5.2 5.9 42.6 -11.6 16 0.1
5000 4.4 39.9 140 27 14 18.0 9.9 5.5 41.9 -12.0 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
03/28/2024 at 0900 MDT | 03/28/2024 at 1200 MDT
|
CAPE... 0.0 LI... +4.9 | CAPE... 0.0 LI... +4.0
CINH... 0.0 K Index... +9.7 | CINH... 0.0 K Index... +14.6
|
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 -59.8 -75.6 255 56 29 -0.2 -0.1 | -59.6 -75.3 255 56 29 -0.4 -0.2
45000 -60.1 -76.2 260 68 35 -0.3 -0.2 | -60.2 -76.4 260 72 37 -0.5 -0.3
40000 -62.5 -80.5 265 85 44 -1.7 -0.9 | -62.0 -79.6 260 90 46 -1.3 -0.7
38000 -62.0 -79.6 265 87 45 4.7 2.6 | -61.5 -78.7 260 93 48 4.3 2.3
36000 -59.3 -74.7 265 82 42 4.6 2.5 | -59.0 -74.2 255 88 46 4.2 2.3
34000 -56.2 -69.2 260 78 40 8.9 4.9 | -56.2 -69.2 255 84 43 8.7 4.8
32000 -51.0 -59.8 260 75 39 8.7 4.8 | -50.9 -59.6 255 80 41 8.8 4.8
30000 -45.8 -50.4 260 73 37 7.7 4.2 | -45.7 -50.3 255 76 39 8.0 4.4
29000 -43.5 -46.3 260 70 36 7.8 4.3 | -43.3 -45.9 255 74 38 8.0 4.4
28000 -41.1 -42.0 260 67 35 7.8 4.3 | -40.9 -41.6 255 72 37 8.0 4.4
27000 -38.8 -37.8 260 65 33 7.9 4.3 | -38.6 -37.5 250 71 36 8.0 4.4
26000 -36.6 -33.9 260 61 32 7.1 3.9 | -36.3 -33.3 250 68 35 7.3 4.0
25000 -34.5 -30.1 260 58 30 7.2 3.9 | -34.1 -29.4 250 65 34 7.3 4.0
24000 -32.3 -26.1 260 55 28 7.1 3.9 | -31.9 -25.4 250 63 32 7.3 4.0
23000 -29.4 -20.9 260 53 27 8.0 4.4 | -29.2 -20.6 250 60 31 7.4 4.1
22000 -27.1 -16.8 255 51 26 8.0 4.4 | -27.0 -16.6 250 57 29 7.4 4.1
21000 -24.7 -12.5 255 49 25 7.7 4.2 | -24.8 -12.6 250 55 28 7.3 4.0
20000 -22.4 -8.3 255 46 24 7.6 4.2 | -22.7 -8.9 245 52 27 7.2 4.0
19500 -21.3 -6.3 255 45 23 7.6 4.2 | -21.6 -6.9 245 50 26 7.2 4.0
19000 -20.2 -4.4 255 44 23 7.7 4.2 | -20.5 -4.9 245 49 25 7.2 4.0
18500 -19.1 -2.4 255 43 22 7.3 4.0 | -19.5 -3.1 245 47 24 7.0 3.8
18000 -18.0 -0.4 250 42 22 7.1 3.9 | -18.5 -1.3 245 46 24 6.8 3.8
17500 -17.0 1.4 250 41 21 7.1 3.9 | -17.5 0.5 245 45 23 6.9 3.8
17000 -15.9 3.4 250 40 20 6.7 3.6 | -16.5 2.3 245 44 22 6.3 3.5
16500 -14.9 5.2 250 39 20 6.7 3.7 | -15.6 3.9 245 42 22 6.4 3.5
16000 -14.0 6.8 245 38 19 5.9 3.2 | -14.6 5.7 245 41 21 6.3 3.5
15500 -13.1 8.4 245 37 19 5.8 3.2 | -13.7 7.3 245 40 20 6.3 3.5
15000 -12.2 10.0 245 36 18 5.3 2.9 | -12.7 9.1 245 38 20 6.0 3.3
14500 -11.5 11.3 240 35 18 4.9 2.7 | -11.9 10.6 245 37 19 5.6 3.1
14000 -10.8 12.6 240 34 18 5.0 2.8 | -11.1 12.0 240 35 18 5.6 3.1
13500 -10.0 14.0 240 33 17 5.3 2.9 | -10.2 13.6 240 34 17 5.6 3.1
13000 -9.3 15.3 235 33 17 5.6 3.1 | -9.4 15.1 240 33 17 5.8 3.2
12500 -8.3 17.1 235 32 16 6.9 3.8 | -8.5 16.7 235 31 16 6.9 3.8
12000 -7.3 18.9 235 31 16 6.9 3.8 | -7.5 18.5 235 30 16 6.9 3.8
11500 -6.3 20.7 230 30 15 7.1 3.9 | -6.3 20.7 230 28 15 7.9 4.3
11000 -5.2 22.6 230 28 14 7.0 3.9 | -5.2 22.6 225 27 14 7.7 4.2
10500 -4.2 24.4 230 26 14 7.1 3.9 | -4.1 24.6 225 24 13 7.0 3.8
10250 -3.6 25.5 230 25 13 6.7 3.7 | -3.6 25.5 225 23 12 7.3 4.0
10000 -3.1 26.4 230 24 13 8.2 4.5 | -3.0 26.6 220 22 12 10.0 5.5
9750 -2.4 27.7 225 24 13 8.1 4.5 | -2.2 28.0 220 22 11 10.1 5.5
9500 -1.9 28.6 220 24 12 6.8 3.7 | -1.5 29.3 215 22 11 8.4 4.6
9250 -1.4 29.5 220 23 12 6.6 3.6 | -0.9 30.4 215 21 11 8.9 4.9
9000 -0.9 30.4 215 23 12 8.7 4.8 | -0.2 31.6 210 20 10 8.5 4.7
8750 -0.1 31.8 220 22 11 8.3 4.6 | 0.4 32.7 215 18 9 9.0 4.9
8500 0.3 32.5 215 21 11 5.7 3.1 | 1.8 35.2 210 18 9 9.4 5.1
8250 1.3 34.3 210 20 11 7.4 4.0 | 2.5 36.5 205 17 9 9.7 5.3
8000 1.9 35.4 210 21 11 6.4 3.5 | 3.3 37.9 210 16 8 9.7 5.3
7750 2.3 36.1 205 19 10 5.3 2.9 | 4.0 39.2 205 16 8 9.6 5.3
7500 2.7 36.9 200 18 9 5.3 2.9 | 4.7 40.5 205 16 8 9.5 5.2
7250 3.0 37.4 195 19 10 4.7 2.6 | 5.4 41.7 205 15 8 9.2 5.0
7000 3.4 38.1 190 19 10 4.8 2.6 | 6.1 43.0 205 14 7 9.9 5.4
6750 3.7 38.7 180 17 9 4.5 2.5 | 6.9 44.4 205 14 7 10.7 5.8
6500 4.0 39.2 175 15 8 3.8 2.1 | 7.7 45.9 200 14 7 10.7 5.8
6250 4.3 39.7 170 14 7 3.0 1.7 | 8.5 47.3 200 13 7 12.0 6.6
6000 4.6 40.3 160 14 7 4.7 2.6 | 9.3 48.7 200 12 6 8.1 4.4
5750 5.1 41.2 160 10 5 9.3 5.1 | 9.8 49.6 200 12 6 9.7 5.3
5500 5.7 42.3 150 8 4 6.7 3.7 | 12.4 54.3 200 10 5 78.0 42.8
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
03/28/2024 at 1500 MDT | 03/28/2024 at 1800 MDT
|
CAPE... +9.9 LI... +1.4 | CAPE... +38.1 LI... -0.2
CINH... -1.5 K Index... +19.5 | CINH... -4.5 K Index... +20.5
|
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 -59.5 -75.1 255 56 29 -0.6 -0.3 | -59.6 -75.3 255 57 29 -0.9 -0.5
45000 -60.4 -76.7 255 75 39 -0.6 -0.3 | -60.9 -77.6 255 76 39 -0.9 -0.5
40000 -62.2 -80.0 260 99 51 -1.3 -0.7 | -62.7 -80.9 260 103 53 -1.2 -0.6
38000 -61.8 -79.2 260 106 54 5.1 2.8 | -62.0 -79.6 260 111 57 5.8 3.2
36000 -58.3 -72.9 260 102 53 5.2 2.9 | -58.5 -73.3 260 111 57 5.8 3.2
34000 -55.0 -67.0 255 99 51 7.2 3.9 | -54.9 -66.8 265 112 58 6.8 3.7
32000 -50.6 -59.1 255 93 48 7.3 4.0 | -50.4 -58.7 260 105 54 7.5 4.1
30000 -46.2 -51.2 255 86 44 8.5 4.7 | -45.9 -50.6 260 99 51 7.7 4.2
29000 -43.7 -46.7 255 83 43 8.3 4.6 | -43.7 -46.7 255 94 48 7.5 4.1
28000 -41.2 -42.2 255 79 41 8.3 4.6 | -41.4 -42.5 255 88 46 7.5 4.1
27000 -38.7 -37.7 255 76 39 8.5 4.6 | -38.6 -37.5 255 82 42 7.5 4.1
26000 -36.5 -33.7 255 74 38 7.3 4.0 | -36.4 -33.5 255 77 40 7.2 3.9
25000 -34.3 -29.7 255 71 37 7.3 4.0 | -34.3 -29.7 255 73 37 7.2 3.9
24000 -32.1 -25.8 250 69 36 7.4 4.0 | -32.1 -25.8 255 68 35 7.2 4.0
23000 -30.0 -22.0 250 66 34 6.9 3.8 | -30.1 -22.2 255 64 33 6.8 3.7
22000 -27.4 -17.3 250 62 32 6.9 3.8 | -28.1 -18.6 255 61 31 6.8 3.7
21000 -25.4 -13.7 250 59 30 7.1 3.9 | -26.0 -14.8 255 57 29 6.9 3.8
20000 -23.2 -9.8 250 55 28 7.2 3.9 | -23.9 -11.0 255 53 27 7.1 3.9
19500 -22.2 -8.0 250 54 28 7.2 3.9 | -22.9 -9.2 255 51 26 7.1 3.9
19000 -21.1 -6.0 245 52 27 7.2 3.9 | -21.8 -7.2 255 49 25 7.1 3.9
18500 -20.1 -4.2 245 50 26 6.9 3.8 | -20.8 -5.4 255 47 24 7.1 3.9
18000 -19.1 -2.4 245 49 25 6.7 3.7 | -19.7 -3.5 250 45 23 7.3 4.0
17500 -18.1 -0.6 245 47 24 6.7 3.7 | -18.6 -1.5 250 43 22 7.2 4.0
17000 -17.1 1.2 245 45 23 6.4 3.5 | -17.5 0.5 245 42 21 7.4 4.1
16500 -16.2 2.8 245 43 22 6.4 3.5 | -16.5 2.3 245 40 21 7.4 4.1
16000 -15.3 4.5 240 40 21 6.5 3.6 | -15.4 4.3 240 39 20 7.7 4.2
15500 -14.3 6.3 240 38 20 6.6 3.6 | -14.2 6.4 240 38 19 7.9 4.3
15000 -13.4 7.9 240 36 19 6.8 3.8 | -13.0 8.6 235 37 19 8.0 4.4
14500 -12.3 9.9 235 34 18 7.2 3.9 | -11.9 10.6 235 36 19 8.2 4.5
14000 -11.3 11.7 235 33 17 7.4 4.1 | -10.6 12.9 230 36 18 8.2 4.5
13500 -10.1 13.8 235 31 16 8.1 4.5 | -9.4 15.1 230 35 18 9.1 5.0
13000 -8.9 16.0 230 30 16 8.2 4.5 | -8.0 17.6 230 34 18 9.0 5.0
12500 -7.6 18.3 230 29 15 8.7 4.8 | -6.6 20.1 225 34 17 9.4 5.2
12000 -6.4 20.5 230 28 14 8.7 4.8 | -5.2 22.6 225 33 17 9.4 5.1
11500 -5.0 23.0 230 27 14 9.6 5.3 | -3.8 25.2 225 33 17 9.5 5.2
11000 -3.5 25.7 225 26 14 9.5 5.2 | -2.4 27.7 225 32 16 9.6 5.3
10500 -2.2 28.0 225 25 13 7.9 4.3 | -1.1 30.0 225 31 16 7.7 4.2
10250 -1.6 29.1 230 25 13 9.2 5.0 | -0.5 31.1 225 30 15 8.7 4.8
10000 -0.8 30.6 225 25 13 11.6 6.4 | 0.2 32.4 225 29 15 11.1 6.1
9750 0.0 32.0 225 25 13 10.5 5.8 | 1.1 34.0 225 29 15 10.6 5.8
9500 0.7 33.3 230 24 12 9.1 5.0 | 1.8 35.2 225 29 15 9.2 5.1
9250 1.4 34.5 230 24 12 9.4 5.2 | 3.2 37.8 225 27 14 9.8 5.4
9000 2.1 35.8 230 23 12 9.7 5.3 | 4.0 39.2 225 27 14 9.7 5.3
8750 2.9 37.2 225 23 12 9.9 5.4 | 4.7 40.5 225 27 14 9.4 5.2
8500 4.3 39.7 225 22 12 9.8 5.4 | 5.4 41.7 225 26 13 9.3 5.1
8250 5.1 41.2 225 22 11 9.9 5.5 | 6.1 43.0 225 26 13 10.3 5.6
8000 5.8 42.4 230 21 11 9.9 5.4 | 6.9 44.4 225 25 13 10.2 5.6
7750 6.5 43.7 230 21 11 9.7 5.3 | 7.6 45.7 225 24 12 9.0 4.9
7500 7.3 45.1 225 20 11 9.6 5.3 | 8.3 46.9 225 23 12 9.4 5.2
7250 8.0 46.4 230 20 10 9.1 5.0 | 9.0 48.2 225 23 12 8.6 4.7
7000 8.6 47.5 230 20 10 9.7 5.3 | 9.6 49.3 225 23 12 9.1 5.0
6750 9.4 48.9 230 19 10 10.2 5.6 | 10.3 50.5 225 21 11 9.9 5.4
6500 10.2 50.4 225 18 9 10.5 5.7 | 11.1 52.0 225 20 10 10.1 5.5
6250 11.0 51.8 230 18 9 11.9 6.5 | 11.9 53.4 225 19 10 11.7 6.4
6000 11.8 53.2 230 17 9 8.4 4.6 | 12.7 54.9 225 19 10 9.2 5.1
5750 12.3 54.1 230 15 8 8.2 4.5 | 13.2 55.8 225 17 9 6.5 3.6
5500 14.3 57.7 230 14 7 59.2 32.5 | 14.4 57.9 225 14 7 34.1 18.7
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
________________________________________________________________________________
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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