Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
563
UXUS97 KGJT 191307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Sunday, May 19, 2024
This forecast is for Sunday, May 19, 2024:
If the trigger temperature of 73.4 F/23.0 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1397 ft/min (7.1 m/s)
Maximum height of thermals.................. 19567 ft MSL (14728 ft AGL)
Forecast maximum temperature................... 83.0 F/28.8 C
Time of trigger temperature.................... 1000 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................. 13943 ft MSL (9104 ft AGL)
Thermal soaring outlook for Monday 05/20....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:57:01 / 20:24:19 MDT
Total possible sunshine........... 14 hr 27 min 17 sec (867 min 17 sec)
Altitude of sun at 13:10:40 MDT... 70.74 degrees
Upper air data from rawinsonde observation taken on 05/19/2024 at 0600 MDT
Freezing level.................. 13087 ft MSL (8248 ft AGL)
Convective condensation level... 14196 ft MSL (9357 ft AGL)
Lifted condensation level....... 15531 ft MSL (10692 ft AGL)
Lifted index.................... -5.1
K index......................... +21.4
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 -54.4 -65.9 245 48 25 0.3 0.2 107.2 224.9 45.4 M M
45000 -53.1 -63.6 250 53 27 0.8 0.4 84.7 184.4 34.7 M M
40000 -54.2 -65.6 265 41 21 -1.6 -0.9 59.9 139.8 20.8 M M
38000 -54.6 -66.3 270 34 17 -1.3 -0.7 50.6 123.1 15.1 M M
36000 -53.6 -64.5 265 32 16 4.5 2.5 43.6 110.4 10.6 M M
34000 -50.5 -58.9 260 25 13 8.9 4.9 38.6 101.5 7.3 M M
32000 -45.2 -49.4 265 25 13 9.4 5.2 37.8 100.8 6.9 M M
30000 -40.2 -40.4 255 28 14 8.5 4.7 36.7 98.0 6.3 M M
29000 -37.4 -35.3 240 26 13 9.4 5.1 36.5 97.7 6.2 M M
28000 -34.9 -30.8 245 25 13 7.2 3.9 35.9 96.7 5.8 M M
27000 -32.5 -26.5 245 26 13 11.0 6.0 35.2 95.4 5.3 M M
26000 -30.2 -22.4 245 27 14 6.9 3.8 34.5 94.0 4.8 M M
25000 -28.3 -18.9 245 30 15 5.2 2.9 33.2 91.8 3.8 M M
24000 -26.5 -15.7 245 31 16 8.7 4.8 31.8 89.2 2.7 M M
23000 -24.0 -11.2 245 33 17 8.4 4.6 31.3 88.3 2.3 M M
22000 -21.5 -6.7 245 34 17 8.4 4.6 30.8 87.4 2.0 M M
21000 -19.0 -2.2 235 34 17 8.4 4.6 30.2 86.4 1.5 M M
20000 -16.8 1.8 235 32 17 4.9 2.7 29.4 84.9 0.8 M M
19500 -16.0 3.2 230 33 17 5.2 2.9 28.5 83.4 0.1 M M
19000 -14.9 5.2 220 35 18 6.1 3.4 27.4 81.3 -1.0 1346 6.8
18500 -13.9 7.0 220 35 18 6.8 3.7 26.9 80.4 -1.5 1301 6.6
18000 -12.8 9.0 225 33 17 8.9 4.9 26.5 79.8 -1.9 1252 6.4
17500 -11.5 11.3 230 32 16 8.9 4.9 26.4 79.5 -2.0 1198 6.1
17000 -10.1 13.8 240 31 16 8.9 4.9 26.3 79.3 -2.1 1143 5.8
16500 -8.8 16.2 245 30 16 8.9 4.9 26.2 79.1 -2.2 1088 5.5
16000 -7.5 18.5 250 30 15 8.9 4.9 26.1 78.9 -2.4 1034 5.3
15500 -6.1 21.0 255 30 15 8.9 4.9 25.9 78.7 -2.5 979 5.0
15000 -4.8 23.4 260 29 15 8.9 4.9 25.8 78.4 -2.7 924 4.7
14500 -3.5 25.7 265 27 14 8.9 4.9 25.6 78.1 -2.8 870 4.4
14000 -2.2 28.0 260 26 13 8.8 4.8 25.5 77.9 -3.0 815 4.1
13500 -0.9 30.4 260 25 13 8.7 4.8 25.3 77.5 -3.3 764 3.9
13000 0.3 32.5 265 23 12 9.0 4.9 25.1 77.3 -3.5 711 3.6
12500 1.6 34.9 255 22 11 9.1 5.0 25.0 77.1 -3.6 656 3.3
12000 3.0 37.4 250 24 12 9.1 5.0 25.0 76.9 -3.7 601 3.1
11500 4.3 39.7 250 21 11 9.1 5.0 24.8 76.7 -3.9 546 2.8
11000 5.7 42.3 245 19 10 9.1 5.0 24.7 76.5 -4.0 491 2.5
10500 7.0 44.6 245 16 8 9.2 5.0 24.6 76.3 -4.2 436 2.2
10250 7.7 45.9 245 14 7 8.9 4.9 24.6 76.2 -4.3 409 2.1
10000 8.3 46.9 245 14 7 8.1 4.4 24.5 76.0 -4.4 383 1.9
9750 8.9 48.0 245 12 6 7.8 4.3 24.3 75.8 -4.5 358 1.8
9500 9.5 49.1 245 9 5 7.9 4.3 24.2 75.5 -4.7 333 1.7
9250 10.0 50.0 240 7 3 7.9 4.3 24.0 75.2 -4.9 309 1.6
9000 10.6 51.1 235 4 2 7.9 4.3 23.9 75.0 -5.0 284 1.4
8750 11.2 52.2 240 4 2 7.8 4.3 23.7 74.7 -5.2 259 1.3
8500 11.8 53.2 265 4 2 8.0 4.4 23.6 74.5 -5.3 235 1.2
8250 12.4 54.3 220 4 2 7.5 4.1 23.4 74.2 -5.5 210 1.1
8000 12.8 55.0 195 6 3 6.4 3.5 23.2 73.8 -5.8 188 1.0
7750 13.3 55.9 185 6 3 6.1 3.4 22.9 73.3 -6.1 167 0.8
7500 13.7 56.7 170 9 5 6.1 3.4 22.7 72.8 -6.4 147 0.7
7250 14.1 57.4 160 11 6 6.5 3.6 22.4 72.3 -6.7 127 0.6
7000 14.6 58.3 155 14 7 5.1 2.8 22.1 71.8 -7.0 106 0.5
6750 14.7 58.5 155 14 7 -0.2 -0.1 21.6 70.9 -7.6 94 0.5
6500 14.7 58.5 150 12 6 3.2 1.7 20.8 69.5 -8.4 88 0.4
6250 15.2 59.4 140 11 6 8.4 4.6 20.6 69.1 -8.6 64 0.3
6000 15.8 60.4 135 10 5 5.9 3.2 20.4 68.8 -8.8 41 0.2
5750 16.1 61.0 125 9 5 4.3 2.3 20.1 68.1 -9.2 24 0.1
5500 16.4 61.5 110 8 4 6.6 3.6 19.7 67.5 -9.7 8 0.0
5250 16.7 62.1 100 9 5 -1.5 -0.8 19.3 66.8 -10.1 M M
5000 15.7 60.3 100 8 4 -25.1 -13.8 17.6 63.7 -11.9 14 0.1
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/19/2024 at 0900 MDT | 05/19/2024 at 1200 MDT
|
CAPE... +13.2 LI... -0.4 | CAPE... +98.6 LI... -1.2
CINH... -42.5 K Index... +21.6 | CINH... -3.5 K Index... +23.6
|
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 -54.7 -66.5 255 49 25 1.1 0.6 | -54.7 -66.5 250 50 26 1.1 0.6
45000 -53.2 -63.8 260 52 27 -0.4 -0.2 | -53.4 -64.1 260 52 27 -1.1 -0.6
40000 -53.9 -65.0 265 48 25 -0.4 -0.2 | -55.2 -67.4 260 57 29 -1.1 -0.6
38000 -53.1 -63.6 270 42 22 2.0 1.1 | -53.8 -64.8 260 53 27 3.2 1.7
36000 -51.7 -61.1 275 35 18 2.0 1.1 | -51.9 -61.4 260 48 25 3.2 1.7
34000 -49.1 -56.4 280 31 16 7.5 4.1 | -48.7 -55.7 265 45 23 7.9 4.3
32000 -44.6 -48.3 275 29 15 7.5 4.1 | -44.0 -47.2 265 42 22 7.8 4.3
30000 -40.0 -40.0 270 28 15 8.0 4.4 | -39.3 -38.7 265 40 21 7.9 4.3
29000 -37.6 -35.7 270 28 14 8.0 4.4 | -36.9 -34.4 260 39 20 7.9 4.3
28000 -35.2 -31.4 265 27 14 8.1 4.4 | -34.6 -30.3 260 38 19 7.9 4.4
27000 -32.8 -27.0 265 27 14 7.5 4.1 | -32.2 -26.0 260 37 19 7.5 4.1
26000 -30.6 -23.1 265 27 14 7.5 4.1 | -30.0 -22.0 260 36 19 7.5 4.1
25000 -28.3 -18.9 265 26 14 7.5 4.1 | -27.8 -18.0 260 35 18 7.5 4.1
24000 -26.1 -15.0 265 26 14 7.1 3.9 | -25.6 -14.1 260 35 18 6.5 3.6
23000 -23.5 -10.3 260 28 14 7.0 3.8 | -23.2 -9.8 260 33 17 6.4 3.5
22000 -21.4 -6.5 260 30 15 7.0 3.8 | -21.3 -6.3 260 31 16 6.4 3.5
21000 -19.4 -2.9 260 30 15 6.8 3.8 | -19.4 -2.9 260 30 15 6.7 3.7
20000 -17.3 0.9 255 30 15 6.9 3.8 | -17.4 0.7 260 29 15 6.8 3.7
19500 -16.3 2.7 255 30 15 6.9 3.8 | -16.5 2.3 260 28 15 6.8 3.7
19000 -15.3 4.5 250 30 15 6.9 3.8 | -15.5 4.1 260 28 14 7.0 3.8
18500 -14.3 6.3 250 30 15 7.1 3.9 | -14.4 6.1 255 28 14 7.6 4.2
18000 -13.2 8.2 245 30 15 7.1 3.9 | -13.3 8.1 250 27 14 7.5 4.1
17500 -12.2 10.0 245 29 15 8.0 4.4 | -12.1 10.2 250 27 14 7.8 4.3
17000 -11.0 12.2 240 29 15 8.2 4.5 | -11.0 12.2 245 27 14 7.9 4.3
16500 -9.8 14.4 240 28 14 8.3 4.6 | -9.8 14.4 245 27 14 8.1 4.4
16000 -8.5 16.7 240 27 14 8.5 4.7 | -8.6 16.5 240 26 13 8.4 4.6
15500 -7.3 18.9 240 26 13 8.6 4.7 | -7.4 18.7 240 25 13 8.4 4.6
15000 -6.0 21.2 240 25 13 8.9 4.9 | -6.1 21.0 240 25 13 9.0 5.0
14500 -4.7 23.5 240 24 13 8.9 4.9 | -4.7 23.5 240 24 12 9.0 4.9
14000 -3.4 25.9 245 24 12 9.1 5.0 | -3.4 25.9 240 23 12 9.2 5.0
13500 -2.0 28.4 245 23 12 9.1 5.0 | -2.0 28.4 240 23 12 9.2 5.0
13000 -0.7 30.7 250 22 11 9.0 4.9 | -0.6 30.9 240 22 11 9.3 5.1
12500 0.6 33.1 250 22 11 9.0 4.9 | 0.7 33.3 240 22 11 9.4 5.1
12000 1.9 35.4 250 21 11 9.0 4.9 | 2.1 35.8 240 21 11 9.4 5.1
11500 3.2 37.8 250 20 10 9.0 4.9 | 3.5 38.3 240 21 11 9.4 5.1
11000 4.6 40.3 250 20 10 7.7 4.2 | 4.9 40.8 245 20 11 8.4 4.6
10500 5.6 42.1 250 19 10 6.0 3.3 | 6.1 43.0 245 20 10 6.9 3.8
10250 6.1 43.0 250 19 10 10.2 5.6 | 6.7 44.1 245 20 10 11.6 6.3
10000 7.0 44.6 245 18 9 10.8 5.9 | 7.7 45.9 245 19 10 12.4 6.8
9750 7.6 45.7 245 17 9 6.9 3.8 | 8.4 47.1 245 19 10 8.3 4.6
9500 8.1 46.6 245 16 8 8.3 4.5 | 9.1 48.4 245 18 9 9.1 5.0
9250 8.7 47.7 245 16 8 6.6 3.6 | 9.7 49.5 245 18 9 10.1 5.5
9000 9.2 48.6 245 16 8 6.2 3.4 | 10.5 50.9 245 17 9 10.5 5.8
8750 9.7 49.5 240 14 7 7.3 4.0 | 11.3 52.3 245 17 9 9.5 5.2
8500 10.7 51.3 235 12 6 6.6 3.6 | 12.7 54.9 245 16 8 9.2 5.1
8250 11.2 52.2 235 11 6 5.9 3.2 | 13.4 56.1 250 16 8 9.4 5.1
8000 11.6 52.9 230 10 5 6.5 3.6 | 14.1 57.4 250 16 8 10.3 5.6
7750 12.1 53.8 225 8 4 7.2 4.0 | 14.9 58.8 250 15 8 10.8 5.9
7500 12.6 54.7 215 7 4 5.8 3.2 | 15.7 60.3 250 15 8 9.3 5.1
7250 13.0 55.4 210 6 3 4.7 2.6 | 16.3 61.3 250 15 8 8.0 4.4
7000 13.4 56.1 200 6 3 8.5 4.7 | 17.0 62.6 255 15 8 10.2 5.6
6750 14.2 57.6 195 6 3 10.6 5.8 | 17.8 64.0 250 14 7 11.4 6.2
6500 14.9 58.8 185 6 3 9.1 5.0 | 18.6 65.5 250 13 7 11.0 6.1
6250 15.6 60.1 180 5 3 8.9 4.9 | 19.5 67.1 255 14 7 12.0 6.6
6000 16.2 61.2 170 4 2 8.5 4.6 | 20.3 68.5 255 14 7 8.2 4.5
5750 16.9 62.4 180 5 3 12.6 6.9 | 20.9 69.6 255 12 6 12.4 6.8
5500 18.7 65.7 165 4 2 44.3 24.3 | 23.9 75.0 260 12 6 89.8 49.2
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
05/19/2024 at 1500 MDT | 05/19/2024 at 1800 MDT
|
CAPE... +70.5 LI... -0.6 | CAPE... +59.7 LI... -0.5
CINH... -12.3 K Index... +20.8 | CINH... -24.9 K Index... +22.5
|
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 -54.9 -66.8 250 52 27 1.4 0.8 | -54.8 -66.6 255 52 27 1.3 0.7
45000 -53.3 -63.9 255 55 28 -1.5 -0.8 | -53.4 -64.1 255 56 29 -1.6 -0.9
40000 -55.7 -68.3 260 64 33 -1.4 -0.8 | -55.9 -68.6 265 66 34 -1.5 -0.8
38000 -54.1 -65.4 260 61 32 3.5 1.9 | -54.2 -65.6 265 63 32 3.8 2.1
36000 -52.0 -61.6 255 57 29 3.5 1.9 | -51.9 -61.4 265 58 30 3.8 2.1
34000 -48.7 -55.7 255 54 28 8.0 4.4 | -48.5 -55.3 260 55 28 7.9 4.3
32000 -43.8 -46.8 260 53 27 8.0 4.4 | -43.7 -46.7 260 52 27 7.9 4.3
30000 -39.0 -38.2 260 50 26 8.1 4.5 | -39.0 -38.2 260 49 25 8.0 4.4
29000 -36.6 -33.9 260 49 25 8.1 4.5 | -36.6 -33.9 260 47 24 8.0 4.4
28000 -34.1 -29.4 260 47 24 8.1 4.5 | -34.2 -29.6 265 45 23 8.0 4.4
27000 -31.8 -25.2 260 45 23 7.2 4.0 | -31.9 -25.4 260 43 22 7.2 3.9
26000 -29.6 -21.3 260 42 22 7.3 4.0 | -29.7 -21.5 260 41 21 7.3 4.0
25000 -27.4 -17.3 260 40 20 7.3 4.0 | -27.5 -17.5 260 39 20 7.3 4.0
24000 -25.3 -13.5 260 37 19 6.4 3.5 | -24.9 -12.8 260 36 19 6.6 3.6
23000 -23.0 -9.4 255 33 17 6.4 3.5 | -22.9 -9.2 255 34 17 6.7 3.7
22000 -21.1 -6.0 255 30 16 6.5 3.5 | -21.0 -5.8 250 31 16 6.7 3.7
21000 -19.1 -2.4 255 28 14 7.4 4.0 | -18.8 -1.8 245 30 16 8.0 4.4
20000 -16.9 1.6 255 26 13 7.4 4.1 | -16.4 2.5 240 30 15 8.1 4.4
19500 -15.8 3.6 250 25 13 7.5 4.1 | -15.3 4.5 240 30 15 8.1 4.4
19000 -14.7 5.5 250 24 12 7.6 4.2 | -14.1 6.6 235 30 15 8.2 4.5
18500 -13.6 7.5 250 23 12 7.9 4.3 | -12.9 8.8 235 29 15 8.3 4.6
18000 -12.4 9.7 250 23 12 7.8 4.3 | -11.6 11.1 230 29 15 8.3 4.6
17500 -11.2 11.8 245 23 12 8.4 4.6 | -10.4 13.3 230 28 14 8.3 4.6
17000 -10.0 14.0 245 23 12 8.5 4.7 | -9.2 15.4 230 27 14 8.4 4.6
16500 -8.7 16.3 245 23 12 8.7 4.8 | -8.0 17.6 230 27 14 8.5 4.7
16000 -7.4 18.7 245 23 12 9.0 4.9 | -6.7 19.9 230 26 13 8.8 4.8
15500 -6.0 21.2 245 23 12 9.0 5.0 | -5.4 22.3 230 26 13 8.8 4.8
15000 -4.7 23.5 245 23 12 9.3 5.1 | -4.0 24.8 230 25 13 9.3 5.1
14500 -3.3 26.1 245 23 12 9.2 5.1 | -2.6 27.3 235 25 13 9.2 5.1
14000 -1.9 28.6 245 23 12 9.3 5.1 | -1.2 29.8 235 24 13 9.4 5.2
13500 -0.5 31.1 245 23 12 9.3 5.1 | 0.2 32.4 235 24 12 9.4 5.2
13000 0.9 33.6 245 23 12 9.2 5.1 | 1.6 34.9 235 24 12 9.5 5.2
12500 2.2 36.0 245 23 12 9.2 5.1 | 3.0 37.4 235 23 12 9.5 5.2
12000 3.6 38.5 245 23 12 9.4 5.2 | 4.4 39.9 240 22 12 9.4 5.1
11500 5.0 41.0 245 23 12 9.5 5.2 | 5.8 42.4 240 22 11 9.3 5.1
11000 6.4 43.5 245 23 12 8.5 4.7 | 7.2 45.0 240 21 11 8.6 4.7
10500 7.6 45.7 245 23 12 7.2 3.9 | 8.4 47.1 245 20 10 7.7 4.2
10250 8.2 46.8 245 23 12 11.7 6.4 | 9.0 48.2 245 20 10 11.3 6.2
10000 9.3 48.7 245 23 12 12.2 6.7 | 10.0 50.0 245 19 10 11.4 6.2
9750 9.9 49.8 250 23 12 8.3 4.5 | 10.7 51.3 245 19 10 8.5 4.7
9500 10.6 51.1 250 23 12 9.0 5.0 | 11.3 52.3 250 18 9 8.9 4.9
9250 11.3 52.3 250 23 12 9.9 5.4 | 12.0 53.6 250 18 9 10.1 5.5
9000 12.1 53.8 250 23 12 10.3 5.6 | 12.8 55.0 250 17 9 10.7 5.9
8750 12.8 55.0 250 22 12 9.2 5.1 | 14.3 57.7 250 16 8 10.0 5.5
8500 14.2 57.6 250 22 11 8.5 4.7 | 15.0 59.0 255 16 8 9.5 5.2
8250 14.8 58.6 255 22 11 8.3 4.6 | 15.7 60.3 255 16 8 9.4 5.1
8000 15.5 59.9 255 21 11 9.8 5.4 | 16.4 61.5 255 16 8 9.8 5.4
7750 16.2 61.2 255 21 11 10.5 5.8 | 17.2 63.0 255 15 8 10.1 5.5
7500 17.0 62.6 255 20 10 8.4 4.6 | 17.9 64.2 255 15 7 9.4 5.2
7250 17.5 63.5 255 20 10 6.4 3.5 | 18.6 65.5 255 15 8 8.6 4.7
7000 18.0 64.4 255 20 10 9.7 5.3 | 19.3 66.7 255 15 7 9.8 5.4
6750 18.9 66.0 255 18 10 11.5 6.3 | 20.0 68.0 260 14 7 10.4 5.7
6500 19.7 67.5 255 18 9 10.7 5.8 | 20.8 69.4 260 13 7 10.5 5.7
6250 20.5 68.9 260 17 9 11.2 6.1 | 21.6 70.9 260 13 7 11.3 6.2
6000 21.2 70.2 260 17 9 8.3 4.5 | 22.4 72.3 260 13 7 8.5 4.6
5750 21.8 71.2 260 16 8 11.5 6.3 | 23.0 73.4 260 12 6 9.4 5.2
5500 24.3 75.7 260 14 7 72.0 39.5 | 24.8 76.6 265 10 5 52.4 28.7
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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