Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
750
UXUS97 KGJT 191306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Saturday, October 19, 2024
This forecast is for Saturday, October 19, 2024:
If the trigger temperature of 64.0 F/17.8 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 297 ft/min (1.5 m/s)
Maximum height of thermals.................. 9375 ft MSL (4536 ft AGL)
Forecast maximum temperature................... 66.0 F/19.3 C
Time of trigger temperature.................... 1330 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................. 8361 ft MSL (3521 ft AGL)
Thermal soaring outlook for Sunday 10/20....... Fair
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:28:44 / 18:29:08 MDT
Total possible sunshine........... 11 hr 0 min 24 sec (660 min 24 sec)
Altitude of sun at 12:58:56 MDT... 40.52 degrees
Upper air data from rawinsonde observation taken on 10/19/2024 at 0600 MDT
Freezing level.................. 11954 ft MSL (7115 ft AGL)
Convective condensation level... 13640 ft MSL (8801 ft AGL)
Lifted condensation level....... 11732 ft MSL (6893 ft AGL)
Lifted index.................... +2.9
K index......................... +19.4
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 -59.5 -75.1 220 12 6 3.1 1.7 100.1 212.1 46.5 M M
45000 -55.2 -67.4 140 5 3 4.9 2.7 82.5 180.5 39.0 M M
40000 -54.3 -65.7 120 11 6 -10.6 -5.8 60.6 141.1 27.3 M M
38000 -54.8 -66.6 170 51 26 -0.8 -0.4 50.0 122.0 21.0 M M
36000 -53.0 -63.4 155 82 42 -1.0 -0.6 44.1 111.4 17.5 M M
34000 -49.9 -57.8 155 70 36 7.5 4.1 40.2 104.3 15.2 M M
32000 -45.8 -50.4 160 61 31 7.9 4.3 37.7 99.8 13.7 M M
30000 -40.6 -41.1 170 48 25 8.2 4.5 36.7 98.1 13.4 M M
29000 -38.2 -36.8 175 38 20 8.2 4.5 36.2 97.1 13.1 M M
28000 -35.7 -32.3 180 32 17 8.2 4.5 35.6 96.0 12.8 M M
27000 -33.3 -27.9 175 27 14 8.2 4.5 34.9 94.8 12.4 M M
26000 -30.8 -23.4 180 24 12 8.0 4.4 34.2 93.6 12.1 M M
25000 -27.9 -18.2 180 20 10 10.1 5.6 34.1 93.4 12.1 M M
24000 -25.2 -13.4 165 20 10 10.0 5.5 33.9 93.0 12.1 M M
23000 -22.3 -8.1 140 21 11 7.1 3.9 33.9 93.0 12.2 M M
22000 -20.7 -5.3 130 20 10 5.3 2.9 32.3 90.1 11.0 M M
21000 -18.8 -1.8 120 20 10 7.3 4.0 31.1 88.0 10.1 M M
20000 -16.0 3.2 125 15 8 8.6 4.7 30.1 86.2 9.4 M M
19500 -14.7 5.5 125 15 8 9.0 5.0 29.9 85.9 9.2 M M
19000 -13.7 7.3 125 14 7 4.3 2.4 29.4 85.0 8.8 M M
18500 -12.9 8.8 125 12 6 6.7 3.7 28.7 83.7 8.3 M M
18000 -11.9 10.6 130 13 7 6.6 3.6 28.2 82.7 7.8 M M
17500 -11.0 12.2 130 11 6 6.5 3.6 27.6 81.7 7.3 M M
17000 -10.0 14.0 140 11 6 8.0 4.4 27.1 80.9 6.9 M M
16500 -8.7 16.3 140 9 5 8.3 4.6 26.9 80.4 6.7 M M
16000 -7.5 18.5 150 11 6 8.3 4.6 26.7 80.0 6.5 M M
15500 -6.3 20.7 155 9 5 8.3 4.6 26.4 79.6 6.3 M M
15000 -5.0 23.0 155 8 4 8.4 4.6 26.2 79.1 6.1 M M
14500 -4.0 24.8 140 12 6 5.7 3.1 25.7 78.3 5.7 M M
14000 -3.2 26.2 105 8 4 5.9 3.2 25.1 77.1 5.1 M M
13500 -2.3 27.9 100 10 5 5.7 3.1 24.5 76.0 4.5 M M
13000 -1.3 29.7 100 9 5 8.4 4.6 24.0 75.3 4.1 M M
12500 -0.1 31.8 115 13 7 2.2 1.2 23.8 74.8 3.8 M M
12000 -0.1 31.8 120 15 8 6.4 3.5 22.3 72.1 2.4 M M
11500 1.0 33.8 110 12 6 7.4 4.0 21.9 71.4 2.1 M M
11000 2.1 35.8 110 13 7 7.4 4.1 21.5 70.8 1.7 M M
10500 3.2 37.8 110 12 6 7.5 4.1 21.2 70.1 1.4 M M
10250 3.8 38.8 105 13 7 7.1 3.9 21.0 69.8 1.2 M M
10000 4.3 39.7 090 13 7 7.4 4.1 20.8 69.4 1.0 M M
9750 4.8 40.6 085 14 7 5.4 2.9 20.5 69.0 0.7 M M
9500 5.0 41.0 080 15 8 3.3 1.8 20.1 68.1 0.3 M M
9250 5.3 41.5 075 17 9 3.3 1.8 19.6 67.2 -0.2 291 1.5
9000 5.6 42.1 070 14 7 4.6 2.5 19.1 66.4 -0.7 276 1.4
8750 5.8 42.4 070 14 7 -2.4 -1.3 18.6 65.4 -1.2 262 1.3
8500 5.3 41.5 070 14 7 -5.9 -3.2 17.3 63.1 -2.4 270 1.4
8250 5.2 41.4 065 13 7 3.6 2.0 16.4 61.6 -3.2 264 1.3
8000 5.6 42.1 065 12 6 6.5 3.6 16.2 61.1 -3.5 244 1.2
7750 6.1 43.0 065 11 6 5.7 3.1 15.9 60.5 -3.8 224 1.1
7500 6.5 43.7 065 9 5 5.9 3.3 15.6 60.0 -4.1 203 1.0
7250 6.9 44.4 070 7 3 5.9 3.2 15.3 59.5 -4.5 183 0.9
7000 7.4 45.3 065 4 2 5.9 3.2 15.0 58.9 -4.8 163 0.8
6750 7.8 46.0 045 3 2 5.9 3.2 14.7 58.4 -5.1 142 0.7
6500 8.2 46.8 005 3 1 5.9 3.2 14.4 57.9 -5.4 122 0.6
6250 8.7 47.7 335 3 2 5.9 3.2 14.1 57.3 -5.7 101 0.5
6000 9.1 48.4 315 4 2 5.8 3.2 13.8 56.8 -6.0 81 0.4
5750 9.5 49.1 305 4 2 6.2 3.4 13.5 56.3 -6.3 61 0.3
5500 10.0 50.0 315 2 1 4.7 2.6 13.2 55.7 -6.6 40 0.2
5250 10.2 50.4 285 1 0 2.6 1.4 12.7 54.8 -7.2 26 0.1
5000 10.2 50.4 190 2 1 -3.7 -2.0 12.0 53.6 -7.9 18 0.1
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
10/19/2024 at 0900 MDT | 10/19/2024 at 1200 MDT
|
CAPE... 0.0 LI... +1.1 | CAPE... 0.0 LI... +0.6
CINH... 0.0 K Index... +19.2 | CINH... 0.0 K Index... +19.9
|
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 -59.1 -74.4 180 7 4 2.0 1.1 | -58.4 -73.1 185 10 5 2.5 1.4
45000 -56.4 -69.5 145 10 5 0.6 0.3 | -55.1 -67.2 145 12 6 -0.2 -0.1
40000 -55.4 -67.7 075 18 9 0.4 0.2 | -55.4 -67.7 085 25 13 -0.4 -0.2
38000 -54.1 -65.4 120 29 15 2.5 1.4 | -54.4 -65.9 110 34 17 2.0 1.1
36000 -52.6 -62.7 135 50 26 2.5 1.4 | -53.1 -63.6 130 49 25 2.0 1.1
34000 -49.8 -57.6 140 60 31 7.0 3.8 | -50.3 -58.5 135 56 29 7.6 4.2
32000 -45.6 -50.1 135 56 29 7.0 3.8 | -45.8 -50.4 135 49 25 7.6 4.2
30000 -41.1 -42.0 140 54 28 8.2 4.5 | -40.9 -41.6 130 44 22 8.6 4.7
29000 -38.6 -37.5 140 53 27 8.2 4.5 | -38.4 -37.1 130 42 22 8.6 4.7
28000 -36.1 -33.0 145 52 27 8.2 4.5 | -35.8 -32.4 130 40 21 8.6 4.7
27000 -33.6 -28.5 145 49 25 8.4 4.6 | -32.6 -26.7 130 38 20 8.4 4.6
26000 -30.5 -22.9 145 42 22 8.4 4.6 | -30.1 -22.2 130 36 19 8.5 4.6
25000 -28.0 -18.4 145 37 19 8.4 4.6 | -27.6 -17.7 125 35 18 8.4 4.6
24000 -25.5 -13.9 145 32 17 8.1 4.4 | -25.2 -13.4 120 32 17 7.5 4.1
23000 -23.1 -9.6 140 28 15 8.1 4.4 | -23.0 -9.4 120 29 15 7.5 4.1
22000 -20.7 -5.3 140 25 13 8.1 4.5 | -20.7 -5.3 115 27 14 7.5 4.1
21000 -18.3 -0.9 135 23 12 7.8 4.3 | -18.5 -1.3 115 25 13 7.4 4.1
20000 -16.0 3.2 125 22 11 7.8 4.3 | -16.3 2.7 110 24 12 7.4 4.1
19500 -14.9 5.2 125 21 11 7.8 4.3 | -15.2 4.6 110 23 12 7.4 4.1
19000 -13.7 7.3 120 21 11 7.9 4.3 | -14.1 6.6 110 23 12 7.9 4.3
18500 -12.6 9.3 120 20 10 7.9 4.3 | -12.9 8.8 110 23 12 8.2 4.5
18000 -11.4 11.5 120 19 10 7.9 4.4 | -11.7 10.9 115 22 12 8.3 4.5
17500 -10.3 13.5 120 19 10 7.4 4.1 | -10.5 13.1 115 22 11 8.0 4.4
17000 -9.2 15.4 120 18 9 7.4 4.1 | -9.3 15.3 115 22 11 8.0 4.4
16500 -8.1 17.4 120 17 9 7.7 4.2 | -8.1 17.4 120 21 11 8.0 4.4
16000 -6.9 19.6 120 16 8 7.7 4.2 | -6.9 19.6 120 20 10 8.0 4.4
15500 -5.8 21.6 120 15 8 7.7 4.2 | -5.7 21.7 120 19 10 7.9 4.4
15000 -4.7 23.5 115 14 7 7.6 4.1 | -4.6 23.7 120 19 10 7.9 4.3
14500 -3.5 25.7 115 14 7 7.6 4.1 | -3.4 25.9 120 18 9 7.9 4.3
14000 -2.5 27.5 110 13 7 7.1 3.9 | -2.3 27.9 120 18 9 7.9 4.3
13500 -1.5 29.3 105 13 7 7.3 4.0 | -1.1 30.0 120 18 9 8.0 4.4
13000 -0.5 31.1 105 13 7 6.0 3.3 | -0.0 32.0 120 18 9 6.8 3.7
12500 0.4 32.7 100 13 7 6.2 3.4 | 1.0 33.8 120 19 10 7.2 3.9
12000 1.2 34.2 100 13 7 5.5 3.0 | 1.9 35.4 120 18 9 4.9 2.7
11500 2.0 35.6 095 13 7 5.5 3.0 | 2.5 36.5 120 17 9 4.9 2.7
11000 2.8 37.0 095 13 7 5.5 3.0 | 3.3 37.9 120 16 8 5.1 2.8
10500 3.6 38.5 095 13 7 5.8 3.2 | 4.0 39.2 120 15 8 5.1 2.8
10250 4.0 39.2 095 13 6 4.5 2.5 | 4.4 39.9 115 14 7 5.3 2.9
10000 4.3 39.7 100 12 6 4.5 2.4 | 4.8 40.6 125 15 8 5.3 2.9
9750 4.7 40.5 100 12 6 5.7 3.1 | 5.1 41.2 120 14 7 5.2 2.8
9500 5.1 41.2 100 12 6 5.5 3.0 | 5.5 41.9 120 13 7 4.8 2.6
9250 5.4 41.7 095 11 6 5.2 2.9 | 6.4 43.5 125 12 6 5.8 3.2
9000 5.8 42.4 100 11 5 4.5 2.5 | 6.7 44.1 120 11 6 3.2 1.7
8750 6.1 43.0 100 10 5 4.3 2.4 | 6.9 44.4 120 9 5 3.3 1.8
8500 6.7 44.1 095 10 5 4.3 2.3 | 7.1 44.8 115 8 4 4.1 2.3
8250 7.1 44.8 100 9 4 4.2 2.3 | 7.5 45.5 120 7 4 4.8 2.6
8000 7.3 45.1 095 8 4 3.0 1.6 | 7.9 46.2 120 6 3 5.4 3.0
7750 7.5 45.5 090 8 4 3.2 1.7 | 8.3 46.9 110 5 2 6.0 3.3
7500 7.8 46.0 090 7 4 4.5 2.4 | 8.7 47.7 115 4 2 6.2 3.4
7250 8.2 46.8 085 7 4 4.9 2.7 | 9.2 48.6 120 4 2 5.9 3.3
7000 8.5 47.3 080 7 3 2.8 1.5 | 9.7 49.5 125 3 2 10.1 5.6
6750 8.6 47.5 075 7 4 2.1 1.1 | 10.6 51.1 110 3 1 11.0 6.0
6500 8.9 48.0 070 7 3 3.2 1.8 | 11.3 52.3 115 2 1 8.5 4.7
6250 9.1 48.4 065 6 3 3.3 1.8 | 11.9 53.4 120 2 1 8.4 4.6
6000 9.3 48.7 060 6 3 2.1 1.1 | 12.6 54.7 125 2 1 11.9 6.6
5750 9.3 48.7 060 4 2 -0.9 -0.5 | 13.8 56.8 110 2 1 21.1 11.6
5500 9.4 48.9 060 3 2 7.2 4.0 | 15.1 59.2 115 2 1 4.4 2.4
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
10/19/2024 at 1500 MDT | 10/19/2024 at 1800 MDT
|
CAPE... +69.8 LI... +0.3 | CAPE... +42.8 LI... -0.1
CINH... -91.4 K Index... +21.8 | CINH... -90.0 K Index... +23.1
|
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 -74.0 190 11 6 2.6 1.4 | -59.6 -75.3 190 7 4 2.4 1.3
45000 -55.3 -67.5 145 13 6 0.4 0.2 | -56.1 -69.0 130 13 6 1.5 0.8
40000 -54.6 -66.3 100 26 14 0.3 0.1 | -53.9 -65.0 105 31 16 1.5 0.8
38000 -53.4 -64.1 120 32 16 2.3 1.3 | -53.4 -64.1 120 32 16 0.7 0.4
36000 -52.0 -61.6 135 40 21 2.3 1.3 | -52.9 -63.2 135 35 18 0.7 0.4
34000 -49.5 -57.1 140 46 24 6.1 3.4 | -50.6 -59.1 140 37 19 7.5 4.1
32000 -45.9 -50.6 140 45 23 6.1 3.4 | -46.2 -51.2 135 37 19 7.5 4.1
30000 -41.5 -42.7 135 44 23 8.5 4.7 | -41.3 -42.3 135 36 19 8.8 4.8
29000 -39.0 -38.2 135 42 22 8.5 4.7 | -38.7 -37.7 135 35 18 8.8 4.8
28000 -36.4 -33.5 135 41 21 8.6 4.7 | -35.4 -31.7 135 34 17 8.8 4.8
27000 -33.1 -27.6 130 38 20 8.9 4.9 | -32.8 -27.0 135 33 17 8.7 4.8
26000 -30.5 -22.9 130 35 18 8.9 4.9 | -30.2 -22.4 135 32 17 8.7 4.8
25000 -27.8 -18.0 125 32 16 8.9 4.9 | -27.6 -17.7 130 32 16 8.7 4.8
24000 -25.3 -13.5 125 30 15 8.2 4.5 | -25.0 -13.0 130 32 16 8.4 4.6
23000 -22.8 -9.0 130 30 15 8.2 4.5 | -22.5 -8.5 130 32 16 8.4 4.6
22000 -20.4 -4.7 130 29 15 8.3 4.5 | -20.0 -4.0 130 32 17 8.5 4.7
21000 -18.1 -0.6 130 28 14 7.5 4.1 | -17.7 0.1 130 32 16 7.4 4.1
20000 -15.9 3.4 130 26 14 7.5 4.1 | -15.5 4.1 130 31 16 7.4 4.1
19500 -14.8 5.4 130 26 13 7.5 4.1 | -14.4 6.1 130 31 16 7.4 4.1
19000 -13.7 7.3 130 25 13 7.6 4.2 | -13.3 8.1 130 30 16 7.5 4.1
18500 -12.5 9.5 130 25 13 7.7 4.2 | -12.2 10.0 130 29 15 7.5 4.1
18000 -11.4 11.5 130 24 12 7.7 4.2 | -11.1 12.0 125 29 15 7.5 4.1
17500 -10.2 13.6 125 24 12 8.1 4.4 | -10.0 14.0 125 28 14 7.3 4.0
17000 -9.0 15.8 125 24 12 8.1 4.4 | -8.9 16.0 125 27 14 7.3 4.0
16500 -7.9 17.8 125 24 12 7.7 4.2 | -7.8 18.0 125 26 14 7.4 4.1
16000 -6.7 19.9 125 24 12 7.6 4.2 | -6.8 19.8 125 26 13 7.5 4.1
15500 -5.6 21.9 125 24 13 7.5 4.1 | -5.7 21.7 120 25 13 7.6 4.2
15000 -4.6 23.7 125 24 12 7.4 4.1 | -4.5 23.9 120 24 13 8.0 4.4
14500 -3.5 25.7 125 24 12 7.4 4.1 | -3.4 25.9 120 24 12 8.0 4.4
14000 -2.4 27.7 125 24 12 7.2 3.9 | -2.3 27.9 115 23 12 7.3 4.0
13500 -1.4 29.5 125 23 12 7.3 4.0 | -1.2 29.8 115 22 11 7.5 4.1
13000 -0.4 31.3 125 22 11 6.5 3.6 | -0.2 31.6 115 20 10 6.5 3.6
12500 0.6 33.1 120 20 10 6.6 3.6 | 0.8 33.4 115 18 9 6.6 3.6
12000 1.5 34.7 120 18 9 6.5 3.6 | 1.7 35.1 115 17 9 6.8 3.7
11500 2.4 36.3 115 16 8 6.6 3.6 | 2.7 36.9 110 14 7 6.8 3.7
11000 3.3 37.9 110 13 7 6.1 3.4 | 3.7 38.7 105 12 6 7.1 3.9
10500 4.2 39.6 100 11 6 6.2 3.4 | 4.7 40.5 095 11 5 7.1 3.9
10250 4.7 40.5 095 10 5 6.0 3.3 | 5.2 41.4 090 10 5 6.9 3.8
10000 5.1 41.2 095 10 5 6.0 3.3 | 5.7 42.3 090 9 5 7.3 4.0
9750 5.5 41.9 090 9 5 6.2 3.4 | 6.3 43.3 085 8 4 8.0 4.4
9500 6.0 42.8 080 8 4 6.0 3.3 | 7.5 45.5 070 7 4 9.3 5.1
9250 6.4 43.5 070 7 4 6.7 3.7 | 8.2 46.8 065 7 3 9.1 5.0
9000 7.0 44.6 075 6 3 7.2 4.0 | 8.8 47.8 060 6 3 7.1 3.9
8750 8.0 46.4 060 5 3 7.0 3.8 | 9.3 48.7 055 6 3 7.6 4.1
8500 8.5 47.3 055 5 2 5.9 3.3 | 9.9 49.8 045 5 3 7.2 4.0
8250 8.9 48.0 055 4 2 6.4 3.5 | 10.4 50.7 040 5 3 7.5 4.1
8000 9.5 49.1 055 4 2 9.8 5.4 | 11.0 51.8 035 4 2 8.5 4.7
7750 10.3 50.5 045 3 2 9.6 5.3 | 11.7 53.1 025 4 2 8.2 4.5
7500 10.9 51.6 045 3 2 7.2 4.0 | 12.2 54.0 015 3 2 6.9 3.8
7250 11.4 52.5 040 3 1 6.8 3.7 | 12.7 54.9 360 3 1 6.6 3.6
7000 12.0 53.6 035 2 1 12.0 6.6 | 13.2 55.8 345 3 1 7.4 4.1
6750 13.1 55.6 035 2 1 12.3 6.7 | 13.8 56.8 325 2 1 8.5 4.7
6500 13.8 56.8 030 2 1 8.8 4.8 | 14.5 58.1 310 3 1 8.7 4.8
6250 14.5 58.1 025 2 1 9.0 5.0 | 15.1 59.2 295 3 2 9.0 5.0
6000 15.2 59.4 020 1 1 11.9 6.5 | 15.8 60.4 285 3 2 6.7 3.7
5750 16.4 61.5 020 1 1 20.7 11.4 | 16.0 60.8 280 3 1 1.7 0.9
5500 17.8 64.0 005 1 1 10.2 5.6 | 16.4 61.5 275 3 2 12.4 6.8
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
________________________________________________________________________________
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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