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Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000
UXUS97 KGJT 131307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Saturday, April 13, 2024
This forecast is for Saturday, April 13, 2024:
If the trigger temperature of 68.5 F/20.3 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1572 ft/min (8.0 m/s)
Maximum height of thermals.................. 20875 ft MSL (16036 ft AGL)
Forecast maximum temperature................... 77.0 F/25.5 C
Time of trigger temperature.................... 1100 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................. 13618 ft MSL (8779 ft AGL)
Thermal soaring outlook for Sunday 04/14....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:39:00 / 19:49:55 MDT
Total possible sunshine........... 13 hr 10 min 55 sec (790 min 55 sec)
Altitude of sun at 13:14:27 MDT... 60.14 degrees
Upper air data from rawinsonde observation taken on 04/13/2024 at 0600 MDT
Freezing level.................. 11948 ft MSL (7109 ft AGL)
Convective condensation level... 16709 ft MSL (11870 ft AGL)
Lifted condensation level....... 17918 ft MSL (13079 ft AGL)
Lifted index.................... -2.5
K index......................... +15.0
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 -56.9 -70.4 255 41 21 -0.8 -0.4 105.5 222.0 46.0 M M
45000 -57.1 -70.8 255 47 24 -9.1 -5.0 80.5 176.8 33.9 M M
40000 -58.2 -72.8 265 45 23 -1.6 -0.9 55.4 131.7 19.9 M M
38000 -55.2 -67.4 280 42 22 5.7 3.1 50.0 122.0 16.9 M M
36000 -51.8 -61.2 285 51 26 5.7 3.1 46.5 115.6 14.9 M M
34000 -48.8 -55.8 275 41 21 2.9 1.6 42.3 108.1 12.3 M M
32000 -44.8 -48.6 275 46 24 7.7 4.2 39.7 103.5 10.7 M M
30000 -40.9 -41.6 265 36 19 4.8 2.7 36.9 98.5 9.0 M M
29000 -39.4 -38.9 270 27 14 5.1 2.8 35.1 95.2 7.7 M M
28000 -37.9 -36.2 265 21 11 5.1 2.8 33.3 92.0 6.4 M M
27000 -36.3 -33.3 255 25 13 5.1 2.8 31.5 88.7 5.1 M M
26000 -34.8 -30.6 250 21 11 5.0 2.8 29.7 85.5 3.7 M M
25000 -34.1 -29.4 245 22 11 0.5 0.3 26.9 80.5 1.5 M M
24000 -31.6 -24.9 245 25 13 9.8 5.4 26.4 79.5 1.1 M M
23000 -28.7 -19.7 245 26 13 9.5 5.2 26.3 79.4 1.0 M M
22000 -25.9 -14.6 230 31 16 9.8 5.4 26.2 79.2 1.0 M M
21000 -23.6 -10.5 215 36 19 6.4 3.5 25.4 77.7 0.3 M M
20000 -21.1 -6.0 210 33 17 8.6 4.7 24.0 75.3 -0.9 1480 7.5
19500 -19.8 -3.6 215 30 15 8.5 4.7 23.8 74.9 -1.1 1427 7.2
19000 -18.5 -1.3 215 27 14 7.9 4.3 23.6 74.5 -1.3 1373 7.0
18500 -17.4 0.7 220 24 12 7.8 4.3 23.2 73.8 -1.6 1325 6.7
18000 -16.3 2.7 220 22 11 7.9 4.3 22.9 73.3 -1.9 1275 6.5
17500 -15.1 4.8 220 19 10 8.0 4.4 22.6 72.7 -2.3 1226 6.2
17000 -14.0 6.8 215 17 9 8.8 4.8 22.3 72.1 -2.6 1176 6.0
16500 -12.5 9.5 220 16 8 9.7 5.3 22.3 72.1 -2.6 1118 5.7
16000 -11.1 12.0 215 16 8 9.7 5.3 22.3 72.1 -2.6 1060 5.4
15500 -9.6 14.7 215 20 10 9.7 5.3 22.3 72.1 -2.7 1001 5.1
15000 -8.2 17.2 220 19 10 9.6 5.3 22.3 72.1 -2.7 943 4.8
14500 -6.8 19.8 210 17 9 9.7 5.3 22.2 72.0 -2.8 886 4.5
14000 -5.4 22.3 225 14 7 9.0 5.0 22.2 72.0 -2.9 829 4.2
13500 -4.1 24.6 230 15 8 8.7 4.8 22.0 71.7 -3.1 776 3.9
13000 -2.8 27.0 245 13 7 8.6 4.7 21.9 71.3 -3.2 722 3.7
12500 -1.5 29.3 250 14 7 9.0 4.9 21.7 71.0 -3.4 668 3.4
12000 -0.1 31.8 245 16 8 9.0 4.9 21.6 70.9 -3.5 613 3.1
11500 1.2 34.2 255 18 9 9.0 4.9 21.5 70.7 -3.7 558 2.8
11000 2.6 36.7 265 14 7 9.0 4.9 21.4 70.4 -3.8 502 2.6
10500 3.9 39.0 265 15 8 9.0 5.0 21.2 70.2 -3.9 447 2.3
10250 4.6 40.3 260 16 8 8.9 4.9 21.2 70.1 -4.0 420 2.1
10000 5.3 41.5 255 18 9 8.6 4.7 21.1 70.0 -4.1 393 2.0
9750 5.9 42.6 255 18 9 8.6 4.7 21.0 69.8 -4.2 366 1.9
9500 6.5 43.7 255 16 8 8.6 4.7 20.9 69.7 -4.3 339 1.7
9250 7.2 45.0 250 13 7 8.6 4.7 20.8 69.5 -4.4 313 1.6
9000 7.8 46.0 265 13 7 8.6 4.7 20.8 69.4 -4.5 286 1.5
8750 8.5 47.3 265 12 6 8.6 4.7 20.7 69.2 -4.6 259 1.3
8500 9.1 48.4 255 12 6 8.6 4.7 20.6 69.0 -4.7 233 1.2
8250 9.8 49.6 235 11 6 8.6 4.7 20.5 68.9 -4.8 206 1.0
8000 10.4 50.7 215 8 4 8.6 4.7 20.4 68.7 -4.9 179 0.9
7750 11.0 51.8 210 8 4 8.6 4.7 20.3 68.6 -5.0 153 0.8
7500 11.7 53.1 180 8 4 8.6 4.7 20.2 68.4 -5.1 126 0.6
7250 12.3 54.1 170 11 6 8.6 4.7 20.1 68.2 -5.2 99 0.5
7000 13.0 55.4 165 14 7 8.6 4.7 20.0 68.1 -5.3 73 0.4
6750 13.6 56.5 165 15 8 8.5 4.7 19.9 67.9 -5.4 46 0.2
6500 14.3 57.7 160 17 9 8.8 4.8 19.8 67.7 -5.5 19 0.1
6250 14.9 58.8 160 19 10 7.0 3.8 19.7 67.5 -5.7 M M
6000 15.4 59.7 160 22 11 8.5 4.7 19.5 67.1 -5.9 M M
5750 15.8 60.4 155 23 12 -0.3 -0.1 19.3 66.7 -6.2 M M
5500 15.4 59.7 150 21 11 -5.7 -3.1 18.1 64.5 -7.4 M M
5250 15.3 59.5 145 17 9 3.1 1.7 17.3 63.1 -8.2 M M
5000 15.4 59.7 130 13 6 -1.8 -1.0 16.7 62.1 -8.9 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/13/2024 at 0900 MDT | 04/13/2024 at 1200 MDT
|
CAPE... +0.3 LI... +1.7 | CAPE... +0.2 LI... +2.9
CINH... -8.7 K Index... +15.6 | CINH... 0.0 K Index... +10.2
|
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 -58.0 -72.4 250 43 22 -0.4 -0.2 | -58.6 -73.5 250 48 25 -0.7 -0.4
45000 -58.6 -73.5 255 47 24 -0.6 -0.3 | -59.6 -75.3 250 52 27 -0.2 -0.1
40000 -59.5 -75.1 255 40 21 -0.4 -0.2 | -60.0 -76.0 245 41 21 -0.2 -0.1
38000 -56.4 -69.5 260 38 19 7.0 3.8 | -56.9 -70.4 250 39 20 6.8 3.7
36000 -52.2 -62.0 260 36 19 7.0 3.8 | -52.8 -63.0 255 39 20 6.8 3.7
34000 -47.9 -54.2 265 36 19 7.4 4.0 | -48.6 -55.5 255 38 20 7.7 4.2
32000 -43.5 -46.3 265 39 20 7.4 4.0 | -44.0 -47.2 260 38 19 7.7 4.2
30000 -39.1 -38.4 265 42 22 7.1 3.9 | -39.4 -38.9 260 37 19 7.4 4.0
29000 -37.0 -34.6 265 44 22 7.1 3.9 | -37.2 -35.0 260 38 19 7.4 4.0
28000 -34.8 -30.6 265 45 23 7.2 3.9 | -35.0 -31.0 260 38 20 7.4 4.0
27000 -32.8 -27.0 265 45 23 5.4 3.0 | -32.8 -27.0 260 38 19 7.1 3.9
26000 -31.2 -24.2 265 39 20 5.2 2.8 | -30.7 -23.3 260 36 19 7.1 3.9
25000 -29.7 -21.5 265 33 17 5.2 2.8 | -28.0 -18.4 265 34 17 7.1 3.9
24000 -27.7 -17.9 265 26 14 5.6 3.1 | -26.0 -14.8 265 31 16 5.8 3.2
23000 -26.0 -14.8 265 24 12 5.6 3.1 | -24.2 -11.6 265 28 14 5.9 3.2
22000 -24.4 -11.9 260 21 11 5.6 3.1 | -22.4 -8.3 265 24 13 5.9 3.2
21000 -22.5 -8.5 255 19 10 7.2 4.0 | -20.6 -5.1 265 21 11 6.3 3.5
20000 -20.4 -4.7 250 18 9 7.2 3.9 | -18.7 -1.7 260 19 10 6.3 3.5
19500 -19.3 -2.7 250 18 9 7.2 3.9 | -17.8 -0.0 260 18 9 6.3 3.5
19000 -18.2 -0.8 250 18 9 7.2 3.9 | -16.8 1.8 255 16 8 6.3 3.5
18500 -17.3 0.9 245 17 9 5.7 3.1 | -15.9 3.4 255 16 8 6.4 3.5
18000 -16.4 2.5 245 15 8 5.9 3.2 | -14.9 5.2 250 15 8 6.4 3.5
17500 -15.5 4.1 240 14 7 6.3 3.5 | -14.0 6.8 245 14 7 5.3 2.9
17000 -14.6 5.7 235 13 7 6.6 3.6 | -13.3 8.1 240 13 7 5.0 2.7
16500 -13.7 7.3 230 12 6 7.2 3.9 | -12.6 9.3 230 12 6 5.4 3.0
16000 -12.5 9.5 230 11 6 8.4 4.6 | -11.7 10.9 225 11 6 6.4 3.5
15500 -11.3 11.7 230 10 5 8.4 4.6 | -10.8 12.6 220 11 6 6.4 3.5
15000 -10.0 14.0 230 10 5 8.9 4.9 | -9.8 14.4 215 11 5 8.0 4.4
14500 -8.7 16.3 235 11 5 8.9 4.9 | -8.6 16.5 210 10 5 7.9 4.3
14000 -7.3 18.9 235 11 6 9.2 5.0 | -7.4 18.7 210 10 5 8.8 4.8
13500 -6.0 21.2 240 12 6 9.2 5.0 | -6.1 21.0 215 10 5 8.8 4.8
13000 -4.6 23.7 245 12 6 9.1 5.0 | -4.8 23.4 220 10 5 9.1 5.0
12500 -3.3 26.1 245 13 7 9.1 5.0 | -3.4 25.9 220 10 5 9.2 5.0
12000 -1.9 28.6 245 14 7 9.0 5.0 | -2.0 28.4 225 10 5 9.2 5.1
11500 -0.5 31.1 250 15 7 9.0 5.0 | -0.6 30.9 230 10 5 9.3 5.1
11000 0.8 33.4 250 15 8 8.9 4.9 | 0.7 33.3 235 11 5 8.7 4.8
10500 2.1 35.8 250 15 8 9.3 5.1 | 2.0 35.6 235 10 5 8.0 4.4
10250 2.7 36.9 250 15 8 6.7 3.7 | 2.7 36.9 240 10 5 10.9 6.0
10000 3.2 37.8 250 16 8 7.2 4.0 | 3.6 38.5 240 11 5 11.3 6.2
9750 3.9 39.0 250 16 8 10.1 5.5 | 4.3 39.7 240 11 5 8.8 4.8
9500 4.6 40.3 250 16 8 9.5 5.2 | 5.0 41.0 240 10 5 9.5 5.2
9250 5.3 41.5 250 15 8 9.0 4.9 | 5.7 42.3 240 10 5 9.4 5.2
9000 5.9 42.6 250 16 8 7.7 4.2 | 6.4 43.5 250 10 5 9.5 5.2
8750 6.4 43.5 250 15 8 7.5 4.1 | 7.8 46.0 245 9 5 9.5 5.2
8500 7.6 45.7 245 13 7 6.9 3.8 | 8.5 47.3 245 9 5 9.1 5.0
8250 8.0 46.4 245 13 7 6.1 3.4 | 9.1 48.4 250 9 5 9.2 5.0
8000 8.5 47.3 245 13 6 6.9 3.8 | 9.9 49.8 250 9 4 10.4 5.7
7750 9.0 48.2 240 11 5 6.9 3.8 | 10.7 51.3 250 8 4 10.5 5.8
7500 9.5 49.1 235 9 5 5.6 3.1 | 11.4 52.5 250 8 4 9.1 5.0
7250 9.9 49.8 235 8 4 4.6 2.5 | 12.0 53.6 250 8 4 8.4 4.6
7000 10.3 50.5 230 7 4 7.3 4.0 | 12.7 54.9 255 8 4 10.9 6.0
6750 10.9 51.6 220 6 3 8.4 4.6 | 13.6 56.5 250 8 4 11.8 6.4
6500 11.5 52.7 215 5 3 7.3 4.0 | 14.5 58.1 250 8 4 10.7 5.9
6250 12.0 53.6 205 4 2 7.2 4.0 | 15.3 59.5 255 7 4 10.3 5.7
6000 12.5 54.5 195 3 2 7.8 4.3 | 16.0 60.8 260 7 4 11.5 6.3
5750 13.2 55.8 190 4 2 12.2 6.7 | 17.2 63.0 250 7 3 21.1 11.6
5500 14.4 57.9 170 2 1 22.0 12.1 | 19.5 67.1 260 6 3 44.4 24.4
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
04/13/2024 at 1500 MDT | 04/13/2024 at 1800 MDT
|
CAPE... +0.6 LI... +3.1 | CAPE... 0.0 LI... +2.8
CINH... -0.1 K Index... +11.1 | CINH... -0.8 K Index... +15.2
|
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 -57.7 -71.9 250 50 26 -0.8 -0.5 | -57.3 -71.1 250 50 26 -1.0 -0.6
45000 -58.9 -74.0 240 56 29 -0.4 -0.2 | -58.8 -73.8 250 55 28 0.3 0.2
40000 -59.5 -75.1 240 42 21 -0.2 -0.1 | -58.3 -72.9 240 41 21 0.4 0.2
38000 -57.0 -70.6 240 39 20 5.7 3.1 | -56.6 -69.9 240 37 19 4.0 2.2
36000 -53.6 -64.5 245 36 19 5.7 3.1 | -54.2 -65.6 240 34 17 4.0 2.2
34000 -49.7 -57.5 245 35 18 7.6 4.2 | -50.9 -59.6 245 32 17 8.0 4.4
32000 -45.1 -49.2 245 35 18 7.6 4.2 | -46.2 -51.2 245 33 17 7.9 4.3
30000 -40.5 -40.9 245 35 18 8.0 4.4 | -41.3 -42.3 250 33 17 8.2 4.5
29000 -38.1 -36.6 245 35 18 8.0 4.4 | -38.9 -38.0 250 33 17 8.2 4.5
28000 -35.6 -32.1 250 35 18 8.0 4.4 | -36.4 -33.5 250 32 16 8.2 4.5
27000 -33.3 -27.9 250 35 18 7.7 4.2 | -34.0 -29.2 250 31 16 8.0 4.4
26000 -30.3 -22.5 250 34 17 7.8 4.3 | -31.0 -23.8 250 30 16 8.0 4.4
25000 -28.0 -18.4 250 33 17 7.8 4.3 | -28.5 -19.3 250 29 15 8.0 4.4
24000 -25.8 -14.4 255 32 16 6.9 3.8 | -26.1 -15.0 250 28 15 7.9 4.3
23000 -23.7 -10.7 255 29 15 7.0 3.8 | -23.8 -10.8 250 26 14 7.9 4.3
22000 -21.6 -6.9 255 27 14 7.0 3.8 | -21.4 -6.5 250 25 13 7.8 4.3
21000 -19.6 -3.3 255 24 13 6.3 3.5 | -19.3 -2.7 250 22 12 6.3 3.5
20000 -17.7 0.1 255 22 11 6.3 3.5 | -17.4 0.7 250 20 10 6.3 3.5
19500 -16.7 1.9 255 20 10 6.3 3.5 | -16.5 2.3 250 18 9 6.3 3.5
19000 -15.8 3.6 250 19 10 6.3 3.4 | -15.5 4.1 250 17 9 6.2 3.4
18500 -14.9 5.2 250 18 9 5.7 3.1 | -14.7 5.5 245 15 8 5.1 2.8
18000 -14.1 6.6 245 16 8 5.8 3.2 | -14.0 6.8 240 14 7 5.3 2.9
17500 -13.2 8.2 240 15 8 6.1 3.4 | -13.2 8.2 235 13 6 6.3 3.5
17000 -12.3 9.9 240 14 7 6.3 3.4 | -12.2 10.0 230 12 6 6.7 3.7
16500 -11.4 11.5 235 14 7 6.5 3.6 | -11.3 11.7 225 12 6 7.1 3.9
16000 -10.4 13.3 230 13 7 7.1 3.9 | -10.1 13.8 220 11 6 8.1 4.4
15500 -9.4 15.1 225 13 7 7.1 3.9 | -8.9 16.0 215 11 6 8.1 4.4
15000 -8.3 17.1 225 12 6 8.5 4.7 | -7.6 18.3 210 10 5 9.4 5.2
14500 -7.0 19.4 220 11 6 8.4 4.6 | -6.2 20.8 205 10 5 9.3 5.1
14000 -5.7 21.7 220 11 6 9.1 5.0 | -4.8 23.4 205 10 5 9.4 5.2
13500 -4.4 24.1 220 10 5 9.1 5.0 | -3.4 25.9 205 10 5 9.4 5.2
13000 -3.0 26.6 220 10 5 9.2 5.0 | -2.0 28.4 205 9 5 9.3 5.1
12500 -1.6 29.1 220 9 5 9.2 5.1 | -0.6 30.9 205 9 5 9.2 5.1
12000 -0.2 31.6 220 9 4 8.9 4.9 | 0.7 33.3 205 8 4 9.2 5.1
11500 1.1 34.0 220 8 4 8.8 4.8 | 2.1 35.8 205 8 4 9.2 5.1
11000 2.4 36.3 225 8 4 8.2 4.5 | 3.5 38.3 210 7 4 7.9 4.3
10500 3.6 38.5 230 7 3 7.4 4.0 | 4.6 40.3 215 6 3 6.1 3.3
10250 4.2 39.6 235 6 3 10.7 5.9 | 5.1 41.2 215 6 3 11.8 6.5
10000 5.1 41.2 230 7 3 11.4 6.3 | 6.2 43.2 210 7 3 13.1 7.2
9750 5.8 42.4 235 6 3 8.5 4.7 | 6.9 44.4 215 7 3 7.9 4.3
9500 6.5 43.7 235 6 3 9.4 5.2 | 7.6 45.7 215 6 3 10.0 5.5
9250 7.2 45.0 240 6 3 8.6 4.7 | 8.3 46.9 220 6 3 6.9 3.8
9000 7.8 46.0 255 6 3 9.2 5.1 | 9.5 49.1 230 5 3 10.3 5.7
8750 9.3 48.7 250 6 3 10.2 5.6 | 10.2 50.4 230 5 3 10.0 5.5
8500 10.1 50.2 250 6 3 9.4 5.2 | 11.0 51.8 225 6 3 8.5 4.6
8250 10.8 51.4 255 6 3 9.1 5.0 | 11.5 52.7 240 5 2 7.6 4.2
8000 11.5 52.7 260 6 3 10.4 5.7 | 12.2 54.0 245 5 2 9.7 5.3
7750 12.3 54.1 255 6 3 10.7 5.9 | 12.9 55.2 235 5 3 10.7 5.8
7500 13.1 55.6 255 6 3 9.1 5.0 | 13.7 56.7 230 5 3 8.9 4.9
7250 13.7 56.7 260 6 3 8.3 4.5 | 14.3 57.7 245 5 3 7.6 4.2
7000 14.4 57.9 265 6 3 11.0 6.1 | 14.9 58.8 250 5 2 10.4 5.7
6750 15.3 59.5 260 6 3 12.0 6.6 | 15.8 60.4 240 5 3 11.5 6.3
6500 16.1 61.0 260 6 3 10.6 5.8 | 16.6 61.9 235 5 3 10.2 5.6
6250 16.9 62.4 270 6 3 10.6 5.8 | 17.4 63.3 245 5 2 10.5 5.7
6000 17.7 63.9 275 6 3 10.1 5.5 | 18.1 64.6 255 5 2 8.2 4.5
5750 18.6 65.5 260 5 3 17.5 9.6 | 18.6 65.5 235 5 3 8.6 4.7
5500 21.2 70.2 280 5 3 59.4 32.6 | 20.3 68.5 260 4 2 47.2 25.9
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
________________________________________________________________________________
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
- Cheyenne, WY Weather Forecast Office
- 1301 Airport Parkway
- Cheyenne, WY 82001-1549
- 307-772-2468
- Page Author: CYS Webmaster
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- Page last modified: Sep 19th, 2023 19:10 UTC