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Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000
UXUS97 KGJT 121307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Friday, April 12, 2024
This forecast is for Friday, April 12, 2024:
If the trigger temperature of 67.8 F/19.9 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1270 ft/min (6.5 m/s)
Maximum height of thermals.................. 18925 ft MSL (14086 ft AGL)
Forecast maximum temperature................... 81.0 F/27.7 C
Time of trigger temperature.................... 1130 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................. 16013 ft MSL (11173 ft AGL)
Thermal soaring outlook for Saturday 04/13..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:40:28 / 19:48:56 MDT
Total possible sunshine........... 13 hr 8 min 28 sec (788 min 28 sec)
Altitude of sun at 13:14:42 MDT... 59.78 degrees
Upper air data from rawinsonde observation taken on 04/12/2024 at 0600 MDT
Freezing level.................. 11886 ft MSL (7047 ft AGL)
Convective condensation level... 20087 ft MSL (15248 ft AGL)
Lifted condensation level....... 20132 ft MSL (15293 ft AGL)
Lifted index.................... -0.3
K index......................... +11.3
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 -58.5 -73.3 270 53 27 0.0 0.0 104.0 219.2 43.7 M M
45000 -57.6 -71.7 265 63 32 -0.7 -0.4 79.5 175.0 31.9 M M
40000 -61.6 -78.9 255 49 25 3.0 1.7 50.1 122.2 15.0 M M
38000 -58.7 -73.7 245 42 22 5.8 3.2 45.7 114.3 12.4 M M
36000 -55.2 -67.4 245 41 21 5.9 3.2 42.2 107.9 10.3 M M
34000 -52.1 -61.8 240 34 18 3.9 2.2 38.3 100.9 7.9 M M
32000 -48.0 -54.4 245 27 14 8.9 4.9 34.8 94.7 5.6 M M
30000 -43.3 -45.9 250 23 12 7.7 4.2 33.2 91.8 4.5 M M
29000 -40.8 -41.4 250 23 12 9.2 5.0 32.7 90.9 4.2 M M
28000 -38.0 -36.4 245 25 13 9.0 5.0 32.5 90.5 4.1 M M
27000 -35.6 -32.1 245 26 13 8.0 4.4 31.9 89.5 3.7 M M
26000 -33.2 -27.8 250 25 13 8.0 4.4 31.3 88.3 3.2 M M
25000 -30.8 -23.4 245 23 12 7.6 4.2 30.6 87.0 2.7 M M
24000 -28.6 -19.5 250 24 12 9.9 5.4 29.7 85.4 1.9 M M
23000 -26.0 -14.8 245 25 13 8.7 4.8 29.3 84.7 1.6 M M
22000 -23.5 -10.3 245 21 11 8.9 4.9 28.9 83.9 1.3 M M
21000 -20.7 -5.3 245 23 12 8.8 4.8 28.6 83.5 1.1 M M
20000 -18.3 -0.9 245 24 12 8.0 4.4 28.1 82.5 0.7 M M
19500 -17.1 1.2 245 25 13 8.1 4.4 27.7 81.9 0.4 M M
19000 -15.9 3.4 245 26 13 8.4 4.6 27.4 81.4 0.1 M M
18500 -15.0 5.0 240 26 14 4.9 2.7 26.9 80.4 -0.4 1243 6.3
18000 -14.2 6.4 240 25 13 5.9 3.2 26.1 79.0 -1.1 1206 6.1
17500 -13.1 8.4 240 26 13 7.5 4.1 25.7 78.2 -1.5 1159 5.9
17000 -11.4 11.5 255 21 11 7.6 4.2 25.1 77.1 -2.0 1086 5.5
16500 -10.3 13.5 270 18 9 8.8 4.8 24.7 76.4 -2.3 1037 5.3
16000 -9.9 14.2 275 15 8 1.0 0.5 23.5 74.3 -3.4 1010 5.1
15500 -9.1 15.6 270 19 10 5.9 3.2 22.9 73.2 -4.1 971 4.9
15000 -8.2 17.2 260 20 10 7.2 3.9 22.3 72.2 -4.7 931 4.7
14500 -7.0 19.4 260 20 10 9.0 4.9 22.1 71.8 -4.9 878 4.5
14000 -5.6 21.9 250 20 10 9.0 4.9 22.0 71.7 -5.0 823 4.2
13500 -4.3 24.3 250 19 10 9.0 4.9 21.9 71.5 -5.1 768 3.9
13000 -2.9 26.8 250 14 7 9.0 4.9 21.8 71.2 -5.3 713 3.6
12500 -1.6 29.1 245 11 6 9.0 4.9 21.7 71.0 -5.4 658 3.3
12000 -0.2 31.6 230 10 5 9.0 4.9 21.5 70.8 -5.6 602 3.1
11500 1.1 34.0 215 11 5 9.0 4.9 21.4 70.5 -5.7 547 2.8
11000 2.5 36.5 200 12 6 9.0 4.9 21.3 70.3 -5.9 492 2.5
10500 3.8 38.8 200 12 6 9.0 4.9 21.1 70.0 -6.0 437 2.2
10250 4.5 40.1 205 13 7 8.8 4.8 21.0 69.8 -6.1 409 2.1
10000 5.1 41.2 200 13 7 8.6 4.7 20.9 69.7 -6.2 383 1.9
9750 5.8 42.4 200 13 6 8.6 4.7 20.8 69.5 -6.4 357 1.8
9500 6.4 43.5 195 12 6 8.7 4.8 20.8 69.4 -6.5 330 1.7
9250 7.0 44.6 195 11 6 8.3 4.5 20.7 69.2 -6.6 304 1.5
9000 7.6 45.7 190 10 5 6.4 3.5 20.5 68.9 -6.8 280 1.4
8750 8.0 46.4 180 11 6 5.4 3.0 20.2 68.3 -7.1 260 1.3
8500 8.4 47.1 165 13 7 5.7 3.1 19.8 67.7 -7.4 239 1.2
8250 8.9 48.0 160 16 8 5.6 3.1 19.5 67.1 -7.7 219 1.1
8000 9.3 48.7 150 19 10 5.9 3.2 19.2 66.6 -8.1 199 1.0
7750 9.7 49.5 150 20 10 4.7 2.6 18.9 66.0 -8.4 178 0.9
7500 9.9 49.8 150 22 11 -1.0 -0.5 18.3 65.0 -9.0 166 0.8
7250 9.6 49.3 140 19 10 -4.5 -2.4 17.3 63.1 -10.0 167 0.8
7000 9.4 48.9 130 16 8 -2.1 -1.2 16.3 61.3 -11.0 167 0.9
6750 9.4 48.9 125 15 8 3.9 2.1 15.6 60.0 -11.7 159 0.8
6500 9.8 49.6 125 16 8 7.5 4.1 15.3 59.6 -12.1 139 0.7
6250 10.1 50.2 125 18 9 -2.2 -1.2 14.9 58.8 -12.5 123 0.6
6000 9.6 49.3 130 21 11 -7.6 -4.2 13.6 56.5 -13.8 131 0.7
5750 9.4 48.9 130 23 12 3.5 1.9 12.7 54.8 -14.8 130 0.7
5500 9.8 49.6 130 24 12 3.0 1.6 12.4 54.2 -15.1 110 0.6
5250 9.6 49.3 130 23 12 -3.8 -2.1 11.5 52.7 -16.1 107 0.5
5000 9.4 48.9 135 21 11 -3.6 -2.0 10.5 50.9 -17.1 108 0.6
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/12/2024 at 0900 MDT | 04/12/2024 at 1200 MDT
|
CAPE... 0.0 LI... +2.7 | CAPE... +0.2 LI... +1.5
CINH... -0.2 K Index... +12.1 | CINH... -0.3 K Index... +15.6
|
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 -58.9 -74.0 255 45 23 1.5 0.8 | -58.9 -74.0 250 45 23 1.2 0.7
45000 -57.0 -70.6 255 51 26 -2.0 -1.1 | -57.2 -71.0 245 51 26 -1.7 -1.0
40000 -59.5 -75.1 250 54 28 -1.7 -1.0 | -59.5 -75.1 245 57 29 -1.6 -0.9
38000 -57.9 -72.2 250 52 27 5.4 3.0 | -57.8 -72.0 240 57 29 5.7 3.1
36000 -54.2 -65.6 245 48 25 5.4 3.0 | -54.0 -65.2 240 54 28 5.7 3.1
34000 -50.8 -59.4 240 43 22 6.0 3.3 | -50.4 -58.7 235 50 26 6.5 3.6
32000 -47.3 -53.1 240 35 18 6.0 3.3 | -46.4 -51.5 235 43 22 6.5 3.6
30000 -43.3 -45.9 235 29 15 8.0 4.4 | -42.5 -44.5 230 36 19 6.7 3.7
29000 -40.9 -41.6 235 27 14 8.0 4.4 | -40.5 -40.9 225 34 17 6.7 3.7
28000 -38.5 -37.3 235 25 13 8.0 4.4 | -38.5 -37.3 215 32 16 6.7 3.7
27000 -36.1 -33.0 235 23 12 8.0 4.4 | -36.4 -33.5 210 30 16 8.2 4.5
26000 -33.7 -28.7 235 23 12 8.0 4.4 | -34.0 -29.2 210 29 15 8.1 4.5
25000 -31.3 -24.3 240 22 11 8.0 4.4 | -31.5 -24.7 210 28 14 8.1 4.5
24000 -28.9 -20.0 240 21 11 7.9 4.3 | -29.1 -20.4 205 27 14 8.2 4.5
23000 -26.6 -15.9 240 22 11 7.9 4.3 | -26.6 -15.9 210 26 14 8.3 4.5
22000 -23.6 -10.5 235 22 11 7.9 4.3 | -23.5 -10.3 210 26 13 8.3 4.5
21000 -21.3 -6.3 235 22 11 7.6 4.2 | -21.2 -6.2 215 25 13 7.2 3.9
20000 -19.1 -2.4 235 22 11 7.6 4.2 | -19.1 -2.4 215 25 13 7.2 3.9
19500 -17.9 -0.2 235 22 12 7.6 4.2 | -18.1 -0.6 215 25 13 7.2 3.9
19000 -16.8 1.8 235 23 12 7.6 4.2 | -17.0 1.4 220 25 13 7.2 4.0
18500 -15.7 3.7 240 22 11 7.5 4.1 | -15.9 3.4 220 24 12 7.4 4.1
18000 -14.6 5.7 240 22 11 7.5 4.1 | -14.8 5.4 220 24 12 7.4 4.1
17500 -13.5 7.7 240 21 11 7.5 4.1 | -13.7 7.3 220 24 12 8.0 4.4
17000 -12.4 9.7 240 20 10 7.5 4.1 | -12.6 9.3 220 23 12 8.1 4.4
16500 -11.3 11.7 240 19 10 7.7 4.2 | -11.4 11.5 215 23 12 8.4 4.6
16000 -10.2 13.6 235 18 9 7.9 4.3 | -10.1 13.8 215 22 11 8.7 4.8
15500 -9.0 15.8 235 17 9 7.9 4.3 | -8.8 16.2 215 21 11 8.7 4.8
15000 -7.8 18.0 235 16 8 8.4 4.6 | -7.5 18.5 215 20 10 8.7 4.8
14500 -6.6 20.1 230 15 8 8.4 4.6 | -6.2 20.8 210 20 10 8.7 4.7
14000 -5.3 22.5 230 14 7 8.7 4.8 | -4.9 23.2 210 19 10 9.1 5.0
13500 -4.0 24.8 225 14 7 8.7 4.7 | -3.6 25.5 210 18 9 9.0 5.0
13000 -2.7 27.1 225 13 7 8.7 4.8 | -2.2 28.0 210 18 9 8.9 4.9
12500 -1.4 29.5 225 13 7 8.7 4.8 | -0.9 30.4 205 17 9 8.9 4.9
12000 -0.1 31.8 220 13 7 8.5 4.7 | 0.4 32.7 205 17 9 8.9 4.9
11500 1.2 34.2 215 12 6 8.5 4.7 | 1.8 35.2 205 16 8 9.0 4.9
11000 2.4 36.3 215 12 6 7.5 4.1 | 3.1 37.6 200 16 8 8.0 4.4
10500 3.5 38.3 210 12 6 6.6 3.6 | 4.2 39.6 200 15 8 7.0 3.9
10250 4.0 39.2 205 12 6 9.7 5.3 | 4.8 40.6 200 15 8 10.5 5.8
10000 4.8 40.6 200 12 6 10.0 5.5 | 5.7 42.3 200 15 7 11.1 6.1
9750 5.4 41.7 200 12 6 7.0 3.8 | 6.4 43.5 195 14 7 7.9 4.4
9500 6.0 42.8 195 12 6 8.0 4.4 | 7.0 44.6 195 14 7 8.9 4.9
9250 6.5 43.7 190 12 6 6.9 3.8 | 7.6 45.7 195 13 7 8.2 4.5
9000 7.0 44.6 190 12 6 6.3 3.5 | 8.2 46.8 190 13 7 8.0 4.4
8750 7.5 45.5 185 12 6 6.8 3.7 | 8.8 47.8 185 12 6 8.3 4.5
8500 8.0 46.4 180 12 6 7.0 3.8 | 9.5 49.1 185 12 6 8.6 4.7
8250 8.9 48.0 175 13 7 4.7 2.6 | 10.1 50.2 180 11 6 6.9 3.8
8000 9.3 48.7 170 13 7 4.8 2.6 | 11.1 52.0 170 11 6 8.7 4.7
7750 9.6 49.3 165 13 7 4.6 2.5 | 11.8 53.2 170 10 5 9.1 5.0
7500 9.9 49.8 160 12 6 3.5 1.9 | 12.4 54.3 165 10 5 7.6 4.2
7250 10.1 50.2 155 13 7 2.7 1.5 | 12.9 55.2 160 10 5 6.9 3.8
7000 10.4 50.7 155 13 7 3.4 1.9 | 13.6 56.5 160 10 5 11.0 6.0
6750 10.6 51.1 150 11 6 3.1 1.7 | 14.5 58.1 160 9 5 12.3 6.8
6500 10.8 51.4 145 10 5 2.5 1.4 | 15.3 59.5 160 9 5 10.1 5.6
6250 11.0 51.8 140 10 5 1.9 1.0 | 16.1 61.0 155 9 5 9.8 5.4
6000 11.1 52.0 135 9 5 4.2 2.3 | 16.8 62.2 155 9 5 10.5 5.8
5750 11.7 53.1 125 6 3 10.9 6.0 | 17.8 64.0 155 8 4 18.6 10.2
5500 12.5 54.5 115 6 3 7.3 4.0 | 20.1 68.2 150 8 4 48.5 26.6
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
04/12/2024 at 1500 MDT | 04/12/2024 at 1800 MDT
|
CAPE... +27.3 LI... -0.1 | CAPE... +23.1 LI... 0.0
CINH... -2.8 K Index... +14.3 | CINH... -10.2 K Index... +13.5
|
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 -58.7 -73.7 250 48 25 1.4 0.7 | -57.9 -72.2 245 46 23 1.7 0.9
45000 -56.9 -70.4 240 53 27 -2.1 -1.1 | -55.6 -68.1 245 49 25 -2.5 -1.4
40000 -59.8 -75.6 235 57 29 -2.0 -1.1 | -59.3 -74.7 235 57 29 -2.5 -1.4
38000 -57.5 -71.5 235 59 31 6.4 3.5 | -57.4 -71.3 230 60 31 5.7 3.2
36000 -53.6 -64.5 235 62 32 6.4 3.5 | -54.0 -65.2 230 63 32 5.7 3.2
34000 -49.8 -57.6 235 61 31 6.4 3.5 | -50.4 -58.7 230 62 32 6.3 3.5
32000 -46.0 -50.8 235 53 27 6.4 3.5 | -46.6 -51.9 225 56 29 6.3 3.5
30000 -42.1 -43.8 230 47 24 6.8 3.7 | -42.8 -45.0 225 50 26 6.6 3.6
29000 -40.0 -40.0 230 44 23 6.8 3.7 | -40.8 -41.4 220 47 24 6.6 3.6
28000 -38.0 -36.4 230 42 22 6.8 3.7 | -38.8 -37.8 220 44 23 6.7 3.6
27000 -35.9 -32.6 225 40 21 7.7 4.2 | -36.8 -34.2 220 41 21 7.9 4.4
26000 -33.6 -28.5 225 38 20 7.7 4.2 | -34.4 -29.9 220 39 20 7.9 4.4
25000 -31.3 -24.3 225 37 19 7.7 4.2 | -32.0 -25.6 215 37 19 7.9 4.4
24000 -28.5 -19.3 220 35 18 7.2 4.0 | -29.1 -20.4 215 35 18 7.7 4.3
23000 -26.3 -15.3 220 33 17 7.3 4.0 | -26.8 -16.2 210 33 17 7.8 4.3
22000 -24.2 -11.6 215 31 16 7.3 4.0 | -24.5 -12.1 210 31 16 7.8 4.3
21000 -21.9 -7.4 215 29 15 7.7 4.2 | -22.0 -7.6 210 29 15 8.5 4.7
20000 -19.7 -3.5 210 28 14 7.7 4.2 | -19.5 -3.1 205 27 14 8.5 4.7
19500 -18.5 -1.3 210 27 14 7.8 4.3 | -18.2 -0.8 205 27 14 8.5 4.7
19000 -17.4 0.7 210 26 14 8.0 4.4 | -17.0 1.4 205 26 13 8.6 4.7
18500 -16.2 2.8 210 26 13 8.8 4.8 | -15.7 3.7 205 25 13 9.0 5.0
18000 -14.9 5.2 210 25 13 8.7 4.8 | -14.3 6.3 205 25 13 9.0 4.9
17500 -13.6 7.5 205 25 13 9.2 5.0 | -13.0 8.6 205 24 13 9.3 5.1
17000 -12.2 10.0 205 25 13 9.2 5.0 | -11.6 11.1 205 24 12 9.3 5.1
16500 -10.8 12.6 205 24 12 9.3 5.1 | -10.2 13.6 205 23 12 9.4 5.2
16000 -9.4 15.1 205 24 12 9.3 5.1 | -8.8 16.2 205 23 12 9.5 5.2
15500 -8.0 17.6 205 23 12 9.3 5.1 | -7.4 18.7 205 23 12 9.6 5.2
15000 -6.6 20.1 205 23 12 9.6 5.3 | -5.9 21.4 205 22 12 9.6 5.3
14500 -5.2 22.6 205 22 12 9.6 5.3 | -4.5 23.9 205 22 11 9.6 5.2
14000 -3.8 25.2 205 22 11 9.5 5.2 | -3.1 26.4 205 22 11 9.7 5.3
13500 -2.3 27.9 200 22 11 9.6 5.2 | -1.6 29.1 205 21 11 9.7 5.3
13000 -0.9 30.4 200 21 11 9.5 5.2 | -0.2 31.6 205 21 11 9.6 5.3
12500 0.5 32.9 200 21 11 9.4 5.2 | 1.3 34.3 205 21 11 9.6 5.3
12000 1.9 35.4 200 20 10 9.5 5.2 | 2.7 36.9 205 20 10 9.6 5.3
11500 3.3 37.9 200 19 10 9.5 5.2 | 4.1 39.4 205 20 10 9.6 5.3
11000 4.7 40.5 200 19 10 8.6 4.7 | 5.5 41.9 205 19 10 8.5 4.7
10500 5.9 42.6 200 18 9 7.3 4.0 | 6.7 44.1 205 19 10 7.1 3.9
10250 6.6 43.9 200 18 9 11.8 6.5 | 7.3 45.1 205 19 10 11.6 6.3
10000 7.6 45.7 200 17 9 12.9 7.1 | 8.4 47.1 205 18 9 12.7 7.0
9750 8.3 46.9 200 17 9 9.1 5.0 | 9.1 48.4 205 18 9 8.8 4.9
9500 9.1 48.4 200 17 9 10.3 5.6 | 9.8 49.6 205 17 9 10.4 5.7
9250 9.8 49.6 200 17 9 9.3 5.1 | 10.6 51.1 205 17 9 8.2 4.5
9000 10.5 50.9 200 17 9 9.5 5.2 | 11.1 52.0 205 17 9 8.4 4.6
8750 12.0 53.6 200 16 8 10.2 5.6 | 12.6 54.7 205 16 8 10.0 5.5
8500 12.8 55.0 200 16 8 9.9 5.5 | 13.4 56.1 210 16 8 10.0 5.5
8250 13.5 56.3 200 16 8 9.9 5.4 | 14.1 57.4 205 16 8 9.9 5.4
8000 14.3 57.7 200 16 8 10.2 5.6 | 14.8 58.6 210 15 8 9.7 5.3
7750 15.0 59.0 200 15 8 10.6 5.8 | 15.6 60.1 210 15 8 10.0 5.5
7500 15.8 60.4 200 15 8 9.2 5.1 | 16.3 61.3 210 14 7 8.9 4.9
7250 16.4 61.5 200 15 8 8.3 4.6 | 16.9 62.4 210 14 7 8.1 4.4
7000 17.1 62.8 200 15 8 10.5 5.8 | 17.6 63.7 210 14 7 9.9 5.4
6750 18.0 64.4 200 14 7 11.4 6.3 | 18.4 65.1 210 13 7 10.8 5.9
6500 18.8 65.8 195 14 7 10.9 6.0 | 19.2 66.6 210 13 6 10.5 5.8
6250 19.6 67.3 195 14 7 11.6 6.4 | 20.0 68.0 210 13 7 11.2 6.1
6000 20.4 68.7 195 14 7 7.9 4.3 | 20.8 69.4 210 13 6 8.1 4.5
5750 21.0 69.8 195 12 6 11.2 6.2 | 21.2 70.2 210 11 6 7.2 4.0
5500 23.8 74.8 195 11 6 84.7 46.5 | 22.8 73.0 210 10 5 45.0 24.7
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.
042613
- National Weather Service
- Austin/San Antonio, TX Weather Forecast Office
- 2090 Airport Road
- New Braunfels, TX 78130
- (830) 629-0130
- Page Author: EWX Webmaster
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- Page last modified: Sep 19th, 2023 19:10 UTC