Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
166
UXUS97 KBOU 270205
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
2004 MDT Friday, April 26, 2024
This forecast is for Saturday, April 27, 2024:
If the trigger temperature of 53.2 F/11.8 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 5287 ft MSL (0 ft AGL)
Forecast maximum temperature................... 42.0 F/6.0 C
Time of trigger temperature.................... None
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Overcast opaque high
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. None
Thermal soaring outlook for Sunday 04/28....... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 14392 ft MSL (9105 ft AGL)
Wave soaring outlook for Sunday 04/28.......... Fair
Remarks... Rainfall persist through Sunday
Sunrise/Sunset.................... 06:03:53 / 19:50:07 MDT
Total possible sunshine........... 13 hr 46 min 15 sec (826 min 15 sec)
Altitude of sun at 12:57:00 MDT... 64.40 degrees
Upper air data from numerical model forecast valid on 04/27/2024 at 0600 MDT
Freezing level.................. 9039 ft MSL (3752 ft AGL)
Convective condensation level... 8185 ft MSL (2898 ft AGL)
Lifted condensation level....... 6409 ft MSL (1122 ft AGL)
Lifted index.................... +5.5
K index......................... +26.0
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 -51.9 -61.4 220 24 12 2.1 1.2 M M M M M
45000 -48.5 -55.3 220 24 12 1.8 1.0 M M M M M
40000 -46.4 -51.5 210 28 14 1.5 0.8 M M M M M
38000 -47.5 -53.5 205 30 15 -8.4 -4.6 M M M M M
36000 -52.6 -62.7 195 33 17 -8.5 -4.6 M M M M M
34000 -57.7 -71.9 190 37 19 -2.8 -1.6 M M M M M
32000 -52.5 -62.5 185 35 18 9.2 5.1 M M M M M
30000 -46.3 -51.3 175 33 17 9.4 5.2 28.9 84.0 17.5 M M
29000 -43.5 -46.3 170 32 16 9.4 5.2 28.6 83.5 17.6 M M
28000 -40.6 -41.1 165 30 16 9.4 5.2 28.5 83.3 17.7 M M
27000 -37.8 -36.0 160 29 15 9.5 5.2 28.5 83.3 17.9 M M
26000 -35.3 -31.5 155 28 14 8.2 4.5 28.0 82.3 17.7 M M
25000 -32.8 -27.0 155 27 14 8.3 4.5 27.4 81.3 17.4 M M
24000 -30.4 -22.7 150 25 13 8.3 4.6 26.9 80.4 17.2 M M
23000 -28.0 -18.4 145 24 12 7.6 4.2 26.2 79.1 16.8 M M
22000 -25.8 -14.4 145 22 11 7.6 4.2 25.4 77.6 16.3 M M
21000 -23.5 -10.3 140 20 10 7.6 4.2 24.7 76.4 15.9 M M
20000 -21.3 -6.3 130 17 9 7.4 4.1 23.8 74.8 15.3 M M
19500 -20.2 -4.4 130 16 8 7.4 4.1 23.4 74.1 15.0 M M
19000 -19.1 -2.4 125 15 8 7.4 4.1 23.0 73.4 14.8 M M
18500 -18.0 -0.4 120 15 7 7.5 4.1 22.6 72.7 14.5 M M
18000 -16.9 1.6 115 14 7 7.0 3.9 22.2 72.0 14.2 M M
17500 -15.9 3.4 105 13 7 7.1 3.9 21.8 71.2 13.9 M M
17000 -14.9 5.2 100 12 6 7.2 4.0 21.3 70.4 13.5 M M
16500 -13.8 7.2 095 12 6 7.3 4.0 20.9 69.6 13.2 M M
16000 -12.7 9.1 085 11 6 7.4 4.0 20.5 68.9 12.9 M M
15500 -11.6 11.1 085 12 6 7.9 4.3 20.1 68.2 12.6 M M
15000 -9.9 14.2 090 13 7 7.6 4.2 19.7 67.4 12.3 M M
14500 -8.8 16.2 095 14 7 7.0 3.8 19.2 66.6 11.9 M M
14000 -7.8 18.0 100 16 8 7.0 3.8 18.8 65.8 11.5 M M
13500 -6.8 19.8 105 17 9 7.1 3.9 18.3 64.9 11.1 M M
13000 -5.8 21.6 115 19 10 7.1 3.9 17.9 64.2 10.7 M M
12500 -4.8 23.4 115 21 11 6.6 3.6 17.4 63.3 10.3 M M
12000 -3.9 25.0 115 24 12 6.7 3.7 16.9 62.4 9.9 M M
11500 -2.9 26.8 110 25 13 6.4 3.5 16.4 61.5 9.4 M M
11000 -2.0 28.4 105 24 13 6.8 3.7 15.8 60.5 8.9 M M
10500 -1.3 29.7 100 24 12 3.6 2.0 15.1 59.2 8.2 M M
10250 -1.0 30.2 100 24 12 3.9 2.1 14.6 58.4 7.8 M M
10000 -0.7 30.7 095 24 12 3.5 1.9 14.2 57.5 7.4 M M
9750 -0.5 31.1 090 24 12 2.8 1.5 13.7 56.6 6.9 M M
9500 -0.3 31.5 085 25 13 2.4 1.3 13.1 55.6 6.3 M M
9250 -0.1 31.8 080 26 13 2.4 1.3 12.5 54.5 5.8 M M
9000 0.0 32.0 075 26 14 2.8 1.5 12.0 53.5 5.3 M M
8750 0.3 32.5 070 27 14 5.2 2.8 11.5 52.7 4.8 M M
8500 0.8 33.4 070 29 15 6.4 3.5 11.2 52.2 4.6 M M
8250 1.2 34.2 065 30 15 6.0 3.3 10.9 51.7 4.3 M M
8000 1.6 34.9 065 31 16 6.4 3.5 10.7 51.2 4.0 M M
7750 2.1 35.8 065 31 16 6.5 3.6 10.4 50.7 3.8 M M
7500 2.6 36.7 060 31 16 6.3 3.4 10.1 50.3 3.5 M M
7250 3.0 37.4 060 30 15 6.4 3.5 9.9 49.8 3.2 M M
7000 3.5 38.3 055 29 15 6.0 3.3 9.6 49.3 2.9 M M
6750 3.9 39.0 055 27 14 6.4 3.5 9.3 48.8 2.7 M M
6500 4.4 39.9 050 26 13 6.9 3.8 9.1 48.4 2.4 M M
6250 4.8 40.6 045 24 12 7.0 3.8 8.9 48.0 2.2 M M
6000 5.4 41.7 040 22 11 7.4 4.0 8.7 47.7 2.0 M M
5750 5.9 42.6 035 20 10 7.4 4.0 8.5 47.3 1.8 M M
5500 6.4 43.5 035 15 8 8.1 4.4 8.4 47.0 1.6 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/27/2024 at 0900 MDT | 04/27/2024 at 1200 MDT
|
CAPE... +32.6 LI... +0.9 | CAPE... +35.0 LI... +2.4
CINH... -0.2 K Index... +24.4 | CINH... -0.1 K Index... +21.7
|
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 -51.4 -60.5 220 24 12 1.6 0.9 | -51.5 -60.7 215 25 13 2.0 1.1
45000 -48.9 -56.0 210 27 14 1.2 0.7 | -48.4 -55.1 205 29 15 1.2 0.6
40000 -47.8 -54.0 205 30 16 0.7 0.4 | -48.1 -54.6 210 30 15 0.1 0.1
38000 -49.0 -56.2 200 28 14 -7.2 -3.9 | -48.8 -55.8 205 27 14 -3.4 -1.8
36000 -53.3 -63.9 190 16 8 -7.2 -4.0 | -50.8 -59.4 180 20 10 -3.4 -1.9
34000 -57.6 -71.7 140 9 5 -5.4 -3.0 | -52.8 -63.0 145 19 10 -3.6 -2.0
32000 -52.6 -62.7 125 10 5 8.6 4.7 | -50.7 -59.3 100 19 10 3.8 2.1
30000 -47.4 -53.3 125 12 6 9.0 5.0 | -48.3 -54.9 070 26 13 8.1 4.4
29000 -44.7 -48.5 125 13 7 8.9 4.9 | -45.6 -50.1 075 25 13 9.0 5.0
28000 -42.0 -43.6 130 14 7 8.9 4.9 | -42.9 -45.2 080 24 12 9.0 5.0
27000 -39.4 -38.9 130 15 8 9.0 4.9 | -40.1 -40.2 080 23 12 9.1 5.0
26000 -36.8 -34.2 135 16 8 8.6 4.7 | -37.6 -35.7 090 20 10 8.5 4.7
25000 -34.2 -29.6 140 17 9 8.7 4.7 | -35.0 -31.0 105 16 8 8.5 4.7
24000 -31.6 -24.9 145 18 9 8.7 4.8 | -32.5 -26.5 120 14 7 8.5 4.7
23000 -29.2 -20.6 150 20 10 7.9 4.3 | -30.0 -22.0 135 14 7 8.4 4.6
22000 -26.9 -16.4 155 22 11 7.9 4.3 | -27.5 -17.5 140 16 8 8.4 4.6
21000 -24.5 -12.1 155 23 12 7.9 4.3 | -25.0 -13.0 140 18 9 8.5 4.7
20000 -22.1 -7.8 155 25 13 8.1 4.4 | -22.8 -9.0 145 21 11 7.2 3.9
19500 -21.0 -5.8 160 26 13 8.1 4.4 | -21.7 -7.1 145 22 12 7.2 4.0
19000 -19.8 -3.6 160 27 14 8.1 4.4 | -20.6 -5.1 145 24 12 7.2 4.0
18500 -18.6 -1.5 160 28 14 8.2 4.5 | -19.1 -2.4 145 26 13 7.3 4.0
18000 -16.9 1.6 160 29 15 7.4 4.0 | -18.0 -0.4 145 27 14 7.3 4.0
17500 -15.8 3.6 155 29 15 7.4 4.1 | -16.9 1.6 145 28 14 7.4 4.0
17000 -14.8 5.4 155 30 15 7.1 3.9 | -15.8 3.6 145 29 15 7.1 3.9
16500 -13.7 7.3 155 30 15 7.1 3.9 | -14.8 5.4 145 29 15 7.1 3.9
16000 -12.7 9.1 150 30 15 7.2 3.9 | -13.8 7.2 145 30 15 7.1 3.9
15500 -11.6 11.1 150 30 15 7.2 3.9 | -12.7 9.1 145 29 15 7.0 3.8
15000 -10.6 12.9 145 30 15 7.1 3.9 | -11.7 10.9 145 29 15 6.8 3.7
14500 -9.6 14.7 145 30 15 6.8 3.7 | -10.8 12.6 140 28 15 6.0 3.3
14000 -8.6 16.5 140 30 15 6.8 3.7 | -9.9 14.2 140 28 14 6.1 3.3
13500 -7.7 18.1 140 29 15 6.2 3.4 | -9.1 15.6 135 26 14 5.2 2.8
13000 -6.8 19.8 135 29 15 6.4 3.5 | -8.3 17.1 130 25 13 5.3 2.9
12500 -5.9 21.4 130 28 15 5.2 2.9 | -7.6 18.3 125 24 12 4.5 2.5
12000 -5.2 22.6 125 28 14 5.4 3.0 | -7.0 19.4 115 23 12 4.6 2.5
11500 -4.5 23.9 120 27 14 4.3 2.4 | -6.3 20.7 105 22 11 4.5 2.5
11000 -3.8 25.2 115 26 13 4.5 2.4 | -5.6 21.9 100 21 11 4.5 2.5
10500 -3.2 26.2 105 25 13 3.6 2.0 | -5.0 23.0 090 20 10 4.8 2.6
10250 -3.0 26.6 100 25 13 3.5 1.9 | -4.6 23.7 085 20 10 4.1 2.3
10000 -2.7 27.1 100 25 13 4.3 2.4 | -4.3 24.3 085 20 10 6.5 3.6
9750 -2.4 27.7 095 24 13 4.3 2.4 | -3.8 25.2 080 18 9 6.5 3.6
9500 -2.1 28.2 095 24 12 3.4 1.9 | -3.4 25.9 075 17 9 4.2 2.3
9250 -1.8 28.8 090 24 12 3.8 2.1 | -3.1 26.4 070 17 9 4.7 2.6
9000 -1.6 29.1 085 23 12 3.1 1.7 | -2.8 27.0 060 16 8 5.1 2.8
8750 -1.4 29.5 085 23 12 3.4 1.8 | -2.4 27.7 060 16 8 5.3 2.9
8500 -1.1 30.0 080 23 12 4.2 2.3 | -2.0 28.4 055 15 8 4.8 2.6
8250 -0.8 30.6 080 23 12 3.7 2.0 | -1.6 29.1 050 15 8 5.1 2.8
8000 -0.5 31.1 075 22 11 4.9 2.7 | -1.3 29.7 045 14 7 4.3 2.3
7750 -0.1 31.8 070 21 11 5.6 3.1 | -1.0 30.2 030 14 7 4.8 2.6
7500 0.3 32.5 070 20 10 5.1 2.8 | -0.6 30.9 030 13 7 6.0 3.3
7250 0.7 33.3 070 19 10 5.2 2.9 | -0.2 31.6 025 13 7 5.7 3.1
7000 1.0 33.8 070 18 9 6.2 3.4 | 0.2 32.4 015 13 7 3.5 1.9
6750 1.5 34.7 065 17 9 7.4 4.1 | 0.4 32.7 005 13 7 5.8 3.2
6500 2.1 35.8 065 16 8 7.3 4.0 | 1.0 33.8 360 13 7 9.6 5.3
6250 2.6 36.7 065 15 7 7.9 4.3 | 1.7 35.1 355 12 6 7.5 4.1
6000 3.2 37.8 060 13 7 9.2 5.1 | 2.1 35.8 350 12 6 5.8 3.2
5750 3.9 39.0 060 11 6 8.1 4.5 | 2.6 36.7 340 12 6 7.3 4.0
5500 4.4 39.9 055 9 5 8.2 4.5 | 3.3 37.9 345 10 5 12.5 6.9
04/27/2024 at 1500 MDT | 04/27/2024 at 1800 MDT
|
CAPE... +22.5 LI... +1.1 | CAPE... +11.4 LI... +0.9
CINH... 0.0 K Index... +22.2 | CINH... 0.0 K Index... +22.9
|
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 -51.9 -61.4 220 26 13 2.0 1.1 | -52.2 -62.0 220 23 12 2.3 1.3
45000 -48.7 -55.7 205 28 15 1.3 0.7 | -48.8 -55.8 215 28 14 1.1 0.6
40000 -48.3 -54.9 210 24 13 0.3 0.2 | -49.3 -56.7 215 19 10 -0.3 -0.2
38000 -48.5 -55.3 210 22 11 -1.5 -0.8 | -49.5 -57.1 205 15 8 -0.6 -0.3
36000 -49.4 -56.9 195 19 10 -1.5 -0.8 | -49.9 -57.8 185 12 6 -0.6 -0.3
34000 -50.3 -58.5 185 17 9 -1.7 -1.0 | -50.2 -58.4 155 12 6 2.4 1.3
32000 -49.4 -56.9 100 13 6 1.7 0.9 | -48.1 -54.6 150 25 13 3.5 1.9
30000 -48.2 -54.8 065 28 14 6.1 3.4 | -46.0 -50.8 150 36 19 5.7 3.1
29000 -45.8 -50.4 065 26 13 8.1 4.5 | -44.1 -47.4 150 32 16 6.3 3.5
28000 -43.4 -46.1 070 24 12 8.2 4.5 | -42.2 -44.0 155 27 14 6.3 3.5
27000 -40.9 -41.6 075 22 12 8.2 4.5 | -40.3 -40.5 155 23 12 6.3 3.4
26000 -38.5 -37.3 080 20 10 7.9 4.3 | -38.2 -36.8 155 17 9 7.4 4.0
25000 -36.2 -33.2 090 16 8 7.9 4.3 | -36.0 -32.8 145 12 6 7.4 4.0
24000 -33.8 -28.8 100 14 7 7.9 4.3 | -33.8 -28.8 120 7 4 7.4 4.0
23000 -31.4 -24.5 115 12 6 8.1 4.4 | -31.3 -24.3 100 4 2 8.7 4.8
22000 -29.0 -20.2 130 13 6 8.1 4.5 | -28.7 -19.7 120 1 1 8.8 4.8
21000 -26.6 -15.9 145 14 7 8.1 4.4 | -26.1 -15.0 260 2 1 8.9 4.9
20000 -24.1 -11.4 150 15 8 8.3 4.6 | -23.7 -10.7 240 3 1 7.9 4.4
19500 -22.9 -9.2 150 15 8 8.3 4.6 | -22.5 -8.5 230 3 1 8.0 4.4
19000 -21.6 -6.9 150 16 8 8.3 4.6 | -21.4 -6.5 215 3 1 8.0 4.4
18500 -19.8 -3.6 155 17 9 8.2 4.5 | -20.2 -4.4 205 3 2 8.1 4.4
18000 -18.6 -1.5 155 17 9 7.7 4.2 | -18.5 -1.3 195 4 2 7.4 4.1
17500 -17.5 0.5 155 17 9 7.8 4.3 | -17.4 0.7 190 4 2 7.5 4.1
17000 -16.3 2.7 155 17 9 7.4 4.1 | -16.3 2.7 185 4 2 7.4 4.1
16500 -15.3 4.5 155 17 9 7.4 4.1 | -15.2 4.6 180 4 2 7.4 4.1
16000 -14.2 6.4 155 17 9 7.1 3.9 | -14.2 6.4 175 4 2 7.1 3.9
15500 -13.2 8.2 150 16 8 6.9 3.8 | -13.1 8.4 180 4 2 6.9 3.8
15000 -12.2 10.0 150 16 8 6.8 3.7 | -12.1 10.2 180 4 2 6.9 3.8
14500 -11.3 11.7 145 16 8 6.5 3.5 | -11.2 11.8 175 4 2 6.7 3.7
14000 -10.3 13.5 140 16 8 6.5 3.6 | -10.2 13.6 175 4 2 6.8 3.7
13500 -9.4 15.1 135 16 8 7.0 3.8 | -9.1 15.6 165 4 2 7.6 4.2
13000 -8.3 17.1 125 16 8 7.2 3.9 | -8.0 17.6 150 5 2 7.6 4.1
12500 -7.5 18.5 120 16 8 5.1 2.8 | -7.0 19.4 140 6 3 7.2 4.0
12000 -6.7 19.9 115 16 8 5.4 3.0 | -5.9 21.4 125 7 4 7.9 4.3
11500 -6.0 21.2 105 16 8 4.2 2.3 | -5.3 22.5 115 8 4 1.2 0.7
11000 -5.4 22.3 100 15 8 4.2 2.3 | -5.0 23.0 100 9 5 1.8 1.0
10500 -4.7 23.5 090 15 8 4.6 2.5 | -4.6 23.7 080 8 4 2.9 1.6
10250 -4.4 24.1 085 16 8 4.5 2.5 | -4.4 24.1 060 8 4 2.6 1.5
10000 -4.1 24.6 080 16 8 4.9 2.7 | -4.2 24.4 045 8 4 3.3 1.8
9750 -3.7 25.3 070 14 7 4.5 2.5 | -3.9 25.0 035 9 5 5.6 3.1
9500 -3.4 25.9 065 14 7 3.8 2.1 | -3.4 25.9 035 10 5 6.7 3.7
9250 -3.1 26.4 055 13 7 3.9 2.1 | -3.0 26.6 040 11 5 6.7 3.7
9000 -2.8 27.0 050 13 7 4.3 2.3 | -2.5 27.5 040 11 6 5.5 3.0
8750 -2.5 27.5 040 12 6 4.0 2.2 | -2.2 28.0 040 13 7 3.7 2.1
8500 -2.3 27.9 035 13 7 3.2 1.8 | -1.9 28.6 035 15 7 3.8 2.1
8250 -2.0 28.4 025 13 7 3.7 2.0 | -1.6 29.1 035 16 8 3.7 2.0
8000 -1.8 28.8 020 14 7 2.5 1.4 | -1.4 29.5 030 17 9 4.1 2.2
7750 -1.6 29.1 010 16 8 3.4 1.9 | -1.1 30.0 025 18 10 3.4 1.8
7500 -1.3 29.7 005 16 8 5.2 2.8 | -0.9 30.4 020 19 10 2.3 1.3
7250 -0.9 30.4 360 16 8 4.7 2.6 | -0.7 30.7 015 20 11 2.7 1.5
7000 -0.6 30.9 355 17 9 2.6 1.4 | -0.5 31.1 010 21 11 2.8 1.5
6750 -0.4 31.3 350 18 9 4.7 2.6 | -0.3 31.5 360 21 11 3.5 1.9
6500 0.1 32.2 345 17 9 7.4 4.1 | -0.0 32.0 355 20 10 3.3 1.8
6250 0.6 33.1 340 16 8 7.7 4.2 | 0.3 32.5 345 19 10 7.0 3.8
6000 1.2 34.2 340 16 8 9.4 5.2 | 1.0 33.8 345 17 9 10.9 6.0
5750 1.9 35.4 335 15 8 8.3 4.5 | 1.7 35.1 340 15 8 8.6 4.7
5500 2.5 36.5 335 13 7 11.7 6.4 | 2.3 36.1 335 13 7 8.8 4.8
________________________________________________________________________________
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 near the old Stapleton
Airport site in Denver, Colorado at
North Latitude: 39 deg 46 min 5.016 sec
West Longitude: 104 deg 52 min 9.984 sec
Elevation: 5285 feet (1611 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.
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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