Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
667
UXUS97 KPUB 031204
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0604 MDT Thursday, April 3, 2025
This forecast is for the Air Force Academy for Thursday, April 3, 2025:
If the trigger temperature of 31.0 F/-0.5 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 305 ft/min (1.6 m/s)
Maximum height of thermals.................. 15666 ft MSL (8029 ft AGL)
Forecast maximum temperature................... 39.0 F/4.3 C
Time of trigger temperature.................... 0945 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 12995 ft MSL (5358 ft AGL)
Thermal soaring outlook for Friday 04/04....... Poor
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:39:45 / 19:25:00 MDT
Total possible sunshine........... 12 hr 45 min 14 sec (765 min 14 sec)
Altitude of sun at 13:02:22 MDT... 56.64 degrees
Upper air data from numerical model forecast valid on 04/03/2025 at 0600 MDT
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 12656 ft MSL (5019 ft AGL)
Lifted condensation level....... 14023 ft MSL (6387 ft AGL)
Lifted index.................... +3.5
K index......................... +10.1
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 -53.8 -64.8 225 40 20 0.8 0.4 M M M M M
45000 -52.7 -62.9 230 51 26 0.7 0.4 M M M M M
40000 -51.2 -60.2 225 70 36 1.0 0.6 M M M M M
38000 -50.7 -59.3 225 78 40 -0.9 -0.5 M M M M M
36000 -52.0 -61.6 220 76 39 -1.9 -1.1 M M M M M
34000 -53.1 -63.6 220 75 39 -1.8 -1.0 M M M M M
32000 -52.0 -61.6 215 79 41 3.3 1.8 M M M M M
30000 -50.0 -58.0 215 85 44 3.3 1.8 M M M M M
29000 -48.5 -55.3 215 84 43 6.4 3.5 17.6 63.7 10.6 M M
28000 -46.5 -51.7 215 79 41 6.4 3.5 16.3 61.3 9.7 M M
27000 -44.6 -48.3 215 75 39 6.5 3.5 15.1 59.2 8.9 M M
26000 -42.7 -44.9 210 69 36 5.5 3.0 13.9 57.0 8.0 M M
25000 -41.1 -42.0 210 58 30 5.3 2.9 12.1 53.8 6.7 M M
24000 -39.6 -39.3 205 47 24 5.3 2.9 10.5 50.9 5.4 M M
23000 -37.2 -35.0 200 37 19 9.1 5.0 9.0 48.3 4.3 M M
22000 -34.5 -30.1 190 35 18 8.9 4.9 8.7 47.6 4.0 M M
21000 -31.9 -25.4 185 34 18 9.0 4.9 8.5 47.2 3.9 M M
20000 -29.5 -21.1 180 32 16 7.4 4.1 7.8 46.1 3.3 M M
19500 -28.4 -19.1 175 31 16 7.4 4.1 7.4 45.3 3.0 M M
19000 -27.3 -17.1 175 30 15 7.4 4.1 7.0 44.6 2.6 M M
18500 -26.2 -15.2 170 29 15 7.4 4.1 6.6 44.0 2.3 M M
18000 -25.1 -13.2 165 28 14 7.3 4.0 6.3 43.3 2.0 M M
17500 -24.0 -11.2 165 26 13 7.3 4.0 5.9 42.5 1.6 M M
17000 -22.9 -9.2 160 25 13 7.1 3.9 5.5 41.8 1.3 M M
16500 -21.9 -7.4 155 23 12 6.5 3.6 4.9 40.9 0.8 M M
16000 -20.9 -5.6 150 22 11 6.6 3.6 4.4 39.9 0.3 M M
15500 -20.0 -4.0 150 21 11 6.4 3.5 3.9 39.0 -0.2 691 3.5
15000 -19.0 -2.2 145 21 11 6.4 3.5 3.3 38.0 -0.7 648 3.3
14500 -18.1 -0.6 140 21 11 6.3 3.4 2.8 37.0 -1.2 605 3.1
14000 -17.2 1.0 135 21 11 6.3 3.4 2.2 36.0 -1.8 562 2.9
13500 -16.3 2.7 135 22 11 5.9 3.2 1.7 35.0 -2.3 520 2.6
13000 -15.4 4.3 130 23 12 4.9 2.7 1.0 33.8 -2.9 480 2.4
12500 -14.1 6.6 130 23 12 9.4 5.2 0.9 33.6 -3.1 426 2.2
12000 -13.3 8.1 130 24 12 5.9 3.3 0.2 32.4 -3.8 386 2.0
11750 -12.8 9.0 130 24 12 6.1 3.4 -0.1 31.9 -4.1 366 1.9
11500 -12.3 9.9 130 24 12 8.4 4.6 -0.3 31.5 -4.3 343 1.7
11250 -11.7 10.9 130 24 12 8.0 4.4 -0.4 31.4 -4.4 316 1.6
11000 -11.1 12.0 130 24 13 6.6 3.6 -0.6 31.0 -4.6 293 1.5
10750 -10.6 12.9 135 25 13 7.5 4.1 -0.8 30.6 -4.8 270 1.4
10500 -10.0 14.0 135 25 13 9.4 5.2 -0.9 30.4 -5.0 244 1.2
10250 -9.3 15.3 135 25 13 9.5 5.2 -0.9 30.4 -5.0 215 1.1
10000 -8.6 16.5 135 25 13 8.2 4.5 -1.0 30.2 -5.1 188 1.0
9750 -8.0 17.6 135 25 13 8.7 4.8 -1.1 30.1 -5.2 162 0.8
9500 -7.3 18.9 135 25 13 9.4 5.1 -1.1 30.0 -5.2 134 0.7
9250 -6.6 20.1 135 25 13 9.1 5.0 -1.2 29.9 -5.3 106 0.5
9000 -6.0 21.2 140 25 13 8.1 4.4 -1.2 29.8 -5.4 80 0.4
8750 -5.4 22.3 140 24 12 6.2 3.4 -1.4 29.4 -5.6 56 0.3
8500 -5.1 22.8 140 22 11 5.2 2.8 -1.8 28.8 -6.0 37 0.2
8250 -4.3 24.3 140 18 9 5.4 3.0 -2.4 27.6 -6.7 M M
8000 -3.8 25.2 140 13 7 7.7 4.2 -2.7 27.2 -7.0 M M
7750 -3.2 26.2 155 6 3 11.1 6.1 -2.7 27.1 -7.1 M M
7500 M M M M M M M M M M M M
7250 M M M M M M M M M M M M
7000 M M M M M M M M M M M M
6750 M M M M M M M M M M M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/03/2025 at 0900 MDT | 04/03/2025 at 1200 MDT
|
CAPE... +8.2 LI... +0.3 | CAPE... +26.9 LI... +0.6
CINH... 0.0 K Index... +10.3 | CINH... -3.9 K Index... +1.8
|
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 -53.2 -63.8 225 38 20 0.4 0.2 | -53.4 -64.1 225 40 21 1.3 0.7
45000 -52.5 -62.5 225 51 26 0.4 0.2 | -51.4 -60.5 220 47 24 1.3 0.7
40000 -51.6 -60.9 220 63 32 0.7 0.4 | -50.7 -59.3 215 58 30 0.3 0.2
38000 -51.3 -60.3 220 67 34 -2.3 -1.2 | -50.6 -59.1 215 62 32 -1.0 -0.5
36000 -52.5 -62.5 215 66 34 -2.0 -1.1 | -51.2 -60.2 210 64 33 -0.9 -0.5
34000 -53.7 -64.7 210 66 34 -1.8 -1.0 | -51.7 -61.1 210 67 35 -0.8 -0.4
32000 -52.3 -62.1 210 67 35 3.7 2.0 | -51.0 -59.8 210 67 34 1.9 1.0
30000 -50.1 -58.2 210 68 35 3.6 2.0 | -49.8 -57.6 210 65 34 1.9 1.0
29000 -48.1 -54.6 210 68 35 8.4 4.6 | -48.2 -54.8 210 65 33 8.1 4.4
28000 -45.6 -50.1 210 68 35 8.5 4.6 | -45.7 -50.3 205 64 33 8.3 4.5
27000 -43.1 -45.6 210 67 35 8.5 4.7 | -43.2 -45.8 205 64 33 8.3 4.5
26000 -40.7 -41.3 210 66 34 5.6 3.1 | -40.8 -41.4 205 63 32 6.0 3.3
25000 -39.1 -38.4 210 58 30 5.2 2.9 | -39.2 -38.6 210 56 29 5.6 3.1
24000 -37.2 -35.0 210 48 25 5.3 2.9 | -37.1 -34.8 210 49 25 5.6 3.1
23000 -35.6 -32.1 210 40 21 5.7 3.1 | -35.3 -31.5 215 43 22 6.9 3.8
22000 -33.8 -28.8 200 33 17 5.7 3.1 | -33.3 -27.9 210 38 20 6.8 3.7
21000 -32.1 -25.8 195 27 14 5.6 3.1 | -31.2 -24.2 205 34 17 6.8 3.7
20000 -30.0 -22.0 185 25 13 8.0 4.4 | -29.2 -20.6 200 31 16 6.5 3.6
19500 -28.8 -19.8 185 25 13 8.1 4.4 | -28.3 -18.9 195 31 16 6.5 3.6
19000 -27.6 -17.7 185 25 13 8.1 4.5 | -27.3 -17.1 195 30 16 6.5 3.6
18500 -26.4 -15.5 180 25 13 8.1 4.5 | -26.3 -15.3 190 30 16 6.6 3.6
18000 -25.2 -13.4 180 25 13 8.4 4.6 | -25.3 -13.5 185 30 16 6.2 3.4
17500 -23.9 -11.0 185 25 13 8.5 4.7 | -24.4 -11.9 185 31 16 6.1 3.4
17000 -22.7 -8.9 185 25 13 8.5 4.7 | -23.5 -10.3 185 33 17 6.5 3.6
16500 -21.4 -6.5 185 26 13 8.6 4.7 | -22.4 -8.3 185 33 17 8.0 4.4
16000 -20.1 -4.2 190 26 13 8.7 4.7 | -21.2 -6.2 190 33 17 7.8 4.3
15500 -18.9 -2.0 190 26 13 7.7 4.2 | -20.0 -4.0 190 32 17 8.7 4.8
15000 -17.8 -0.0 190 27 14 7.9 4.3 | -18.7 -1.7 195 32 16 8.7 4.8
14500 -16.7 1.9 190 27 14 6.8 3.7 | -17.4 0.7 200 31 16 8.8 4.8
14000 -15.7 3.7 185 26 13 6.7 3.7 | -16.1 3.0 200 29 15 8.9 4.9
13500 -14.8 5.4 185 25 13 4.7 2.6 | -14.8 5.4 205 28 14 10.0 5.5
13000 -14.2 6.4 175 21 11 3.4 1.8 | -13.2 8.2 205 26 14 11.4 6.3
12500 -13.4 7.9 170 18 9 6.6 3.6 | -12.2 10.0 205 25 13 5.4 2.9
12000 -12.7 9.1 150 17 9 4.7 2.6 | -10.9 12.4 205 23 12 8.2 4.5
11750 -12.4 9.7 140 17 9 4.6 2.5 | -10.3 13.5 210 22 11 8.8 4.8
11500 -12.0 10.4 130 18 9 7.2 3.9 | -9.6 14.7 210 21 11 8.0 4.4
11250 -11.4 11.5 120 19 10 7.3 4.0 | -9.2 15.4 210 19 10 4.4 2.4
11000 -10.9 12.4 120 20 10 5.6 3.1 | -9.0 15.8 210 17 9 2.6 1.4
10750 -10.5 13.1 115 21 11 6.1 3.3 | -8.8 16.2 210 14 7 3.0 1.7
10500 -10.0 14.0 115 22 11 6.8 3.7 | -8.7 16.3 210 12 6 -1.4 -0.8
10250 -9.5 14.9 115 22 12 6.1 3.4 | -8.9 16.0 210 9 5 0.3 0.2
10000 -9.1 15.6 115 22 12 4.9 2.7 | -8.6 16.5 200 7 4 5.4 3.0
9750 -8.8 16.2 115 22 11 4.1 2.2 | -8.2 17.2 190 5 3 5.5 3.0
9500 -8.6 16.5 115 21 11 1.9 1.0 | -7.8 18.0 165 4 2 6.7 3.7
9250 -8.4 16.9 115 19 10 2.0 1.1 | -7.3 18.9 145 4 2 7.5 4.1
9000 -8.2 17.2 115 17 9 4.3 2.4 | -6.7 19.9 125 5 3 9.5 5.2
8750 -7.8 18.0 120 14 7 7.7 4.2 | -5.9 21.4 115 6 3 10.5 5.8
8500 -6.5 20.3 120 11 6 8.8 4.8 | -5.2 22.6 110 6 3 10.3 5.6
8250 -5.8 21.6 125 9 5 10.2 5.6 | -4.4 24.1 105 5 3 9.9 5.4
8000 -4.9 23.2 125 8 4 16.3 8.9 | -3.7 25.3 100 5 3 10.8 5.9
7750 -3.4 25.9 120 7 4 23.6 12.9 | -2.6 27.3 100 5 3 18.6 10.2
7500 M M M M M M M | M M M M M M M
7250 M M M M M M M | M M M M M M M
7000 M M M M M M M | M M M M M M M
6750 M M M M M M M | M M M M M M M
04/03/2025 at 1500 MDT | 04/03/2025 at 1800 MDT
|
CAPE... +131.0 LI... -1.1 | CAPE... +84.8 LI... -0.9
CINH... 0.0 K Index... +15.8 | CINH... -5.8 K Index... +16.0
|
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 -53.8 -64.8 225 39 20 0.9 0.5 | -54.1 -65.4 230 37 19 0.6 0.4
45000 -52.4 -62.3 225 51 26 0.9 0.5 | -53.1 -63.6 230 45 23 0.7 0.4
40000 -51.2 -60.2 220 57 29 0.8 0.4 | -51.1 -60.0 220 56 29 1.3 0.7
38000 -50.8 -59.4 215 59 31 -0.5 -0.3 | -50.6 -59.1 215 60 31 -1.3 -0.7
36000 -51.0 -59.8 215 62 32 -0.4 -0.2 | -51.3 -60.3 215 65 33 -1.1 -0.6
34000 -51.3 -60.3 215 64 33 -0.3 -0.2 | -52.0 -61.6 220 70 36 -1.1 -0.6
32000 -50.4 -58.7 215 67 34 2.1 1.1 | -51.0 -59.8 220 70 36 2.5 1.4
30000 -49.2 -56.6 220 69 35 2.0 1.1 | -49.5 -57.1 220 69 35 2.3 1.3
29000 -47.8 -54.0 220 69 35 6.4 3.5 | -47.8 -54.0 220 67 34 7.4 4.1
28000 -45.9 -50.6 220 68 35 6.5 3.6 | -45.6 -50.1 220 64 33 7.5 4.1
27000 -43.9 -47.0 220 67 34 6.5 3.6 | -43.3 -45.9 220 61 32 7.5 4.1
26000 -42.0 -43.6 220 65 33 6.6 3.6 | -41.1 -42.0 225 58 30 6.2 3.4
25000 -40.0 -40.0 220 58 30 6.6 3.6 | -38.8 -37.8 220 52 27 6.1 3.4
24000 -37.5 -35.5 220 49 25 6.6 3.6 | -37.0 -34.6 220 46 24 6.1 3.4
23000 -35.5 -31.9 220 44 23 6.8 3.8 | -35.2 -31.4 220 42 22 5.8 3.2
22000 -33.5 -28.3 215 42 21 6.8 3.7 | -33.5 -28.3 210 39 20 5.8 3.2
21000 -31.4 -24.5 215 39 20 6.8 3.7 | -31.7 -25.1 205 37 19 5.7 3.1
20000 -29.4 -20.9 210 38 20 7.1 3.9 | -29.5 -21.1 200 36 19 8.4 4.6
19500 -28.3 -18.9 205 38 20 7.1 3.9 | -28.2 -18.8 195 36 19 8.5 4.7
19000 -27.2 -17.0 205 38 20 7.1 3.9 | -27.0 -16.6 190 36 19 8.5 4.7
18500 -26.2 -15.2 205 38 20 7.1 3.9 | -25.7 -14.3 190 36 19 8.5 4.7
18000 -25.1 -13.2 200 38 19 8.2 4.5 | -24.5 -12.1 185 36 18 8.8 4.8
17500 -23.8 -10.8 205 35 18 8.5 4.7 | -23.1 -9.6 190 33 17 8.9 4.9
17000 -22.6 -8.7 205 32 17 8.6 4.7 | -21.8 -7.2 195 30 16 8.7 4.8
16500 -21.3 -6.3 205 30 15 8.7 4.8 | -20.6 -5.1 195 29 15 8.2 4.5
16000 -20.0 -4.0 210 28 14 8.8 4.8 | -19.4 -2.9 195 28 15 8.2 4.5
15500 -18.8 -1.8 210 26 14 7.9 4.3 | -18.2 -0.8 195 27 14 7.6 4.2
15000 -17.6 0.3 205 25 13 8.0 4.4 | -17.1 1.2 195 26 13 7.7 4.2
14500 -16.4 2.5 205 24 12 7.9 4.4 | -15.9 3.4 195 24 13 8.1 4.4
14000 -15.2 4.6 205 24 12 7.9 4.3 | -14.7 5.5 195 24 13 8.0 4.4
13500 -14.0 6.8 200 23 12 8.4 4.6 | -13.5 7.7 195 24 13 9.1 5.0
13000 -12.8 9.0 200 23 12 9.4 5.1 | -12.1 10.2 195 24 12 10.3 5.7
12500 -12.0 10.4 195 22 11 3.7 2.0 | -11.2 11.8 190 24 12 4.3 2.3
12000 -11.1 12.0 190 21 11 6.0 3.3 | -10.1 13.8 185 23 12 7.4 4.0
11750 -10.6 12.9 185 20 10 6.2 3.4 | -9.5 14.9 185 23 12 8.4 4.6
11500 -10.2 13.6 185 19 10 5.9 3.2 | -8.9 16.0 185 23 12 8.8 4.8
11250 -9.7 14.5 175 18 9 6.2 3.4 | -8.3 17.1 180 21 11 6.9 3.8
11000 -9.3 15.3 170 17 9 6.4 3.5 | -7.8 18.0 180 21 11 5.8 3.2
10750 -8.8 16.2 165 16 8 6.5 3.6 | -7.4 18.7 175 20 10 6.4 3.5
10500 -8.3 17.1 155 15 8 7.9 4.4 | -6.9 19.6 175 18 10 7.2 3.9
10250 -7.7 18.1 150 14 7 8.8 4.8 | -6.3 20.7 170 17 9 8.2 4.5
10000 -7.1 19.2 150 14 7 8.5 4.6 | -5.7 21.7 170 16 8 8.6 4.7
9750 -6.4 20.5 145 14 7 8.8 4.8 | -5.1 22.8 165 15 8 8.7 4.8
9500 -5.8 21.6 145 14 7 9.5 5.2 | -4.4 24.1 165 14 7 9.1 5.0
9250 -5.0 23.0 145 14 7 9.9 5.4 | -3.7 25.3 165 14 7 9.3 5.1
9000 -4.3 24.3 140 13 7 10.4 5.7 | -3.0 26.6 165 14 7 9.7 5.3
8750 -3.5 25.7 140 13 7 10.4 5.7 | -2.3 27.9 165 13 7 10.0 5.5
8500 -2.8 27.0 140 13 7 10.1 5.6 | -1.6 29.1 165 13 7 10.1 5.6
8250 -2.0 28.4 140 13 7 10.0 5.5 | -0.8 30.6 165 13 7 10.2 5.6
8000 -1.3 29.7 140 13 7 10.2 5.6 | -0.1 31.8 165 12 6 8.8 4.8
7750 -0.4 31.3 140 12 6 14.7 8.1 | 1.1 34.0 160 8 4 13.9 7.6
7500 M M M M M M M | M M M M M M M
7250 M M M M M M M | M M M M M M M
7000 M M M M M M M | M M M M M M M
6750 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). 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 near the Air Force Academy
in Colorado Springs, Colorado at
North Latitude: 38 deg 58 min 48.000 sec
West Longitude: 104 deg 49 min 12.000 sec
Elevation: 6572 feet (2003 meters)
and may not be representative of other areas along the Front Range of the
Colorado Rocky Mountains. 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.
CIN (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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