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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 191253
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0653 MDT Friday, April 19, 2024
This forecast is for Friday, April 19, 2024:
If the trigger temperature of 53.9 F/12.2 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 8157 ft MSL (2896 ft AGL)
Forecast maximum temperature................... 44.0 F/7.1 C
Time of trigger temperature.................... None
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................. 6421 ft MSL (1160 ft AGL)
Thermal soaring outlook for Saturday 04/20..... Poor
Wave Soaring Index............................. Fair
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 21528 ft MSL (16267 ft AGL)
Wave soaring outlook for Saturday 04/20........ Poor
Remarks...
Sunrise/Sunset.................... 06:14:47 / 19:42:04 MDT
Total possible sunshine........... 13 hr 27 min 17 sec (807 min 17 sec)
Altitude of sun at 12:58:26 MDT... 61.77 degrees
Upper air data from numerical model forecast valid on 04/19/2024 at 0600 MDT
Freezing level.................. 6572 ft MSL (1311 ft AGL)
Additional freezing levels...... 9223 ft MSL (3962 ft AGL)
11057 ft MSL (5796 ft AGL)
Convective condensation level... 14329 ft MSL (9068 ft AGL)
Lifted condensation level....... 8959 ft MSL (3698 ft AGL)
Lifted index.................... +11.4
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 -57.9 -72.2 260 55 28 2.8 1.5 M M M M M
45000 -53.8 -64.8 265 61 31 -3.1 -1.7 M M M M M
40000 -58.4 -73.1 260 73 38 -3.1 -1.7 M M M M M
38000 -57.5 -71.5 265 72 37 4.9 2.7 M M M M M
36000 -54.5 -66.1 265 67 35 4.9 2.7 M M M M M
34000 -51.2 -60.2 265 62 32 7.4 4.1 M M M M M
32000 -46.2 -51.2 265 57 29 7.4 4.1 M M M M M
30000 -41.5 -42.7 265 53 27 8.6 4.7 34.7 94.4 21.1 M M
29000 -39.0 -38.2 265 53 27 8.6 4.7 34.2 93.5 20.9 M M
28000 -36.4 -33.5 265 52 27 8.6 4.7 33.8 92.8 20.9 M M
27000 -33.8 -28.8 265 51 26 7.9 4.3 33.4 92.1 20.8 M M
26000 -31.5 -24.7 260 50 26 7.8 4.3 32.5 90.6 20.4 M M
25000 -29.1 -20.4 260 49 25 7.8 4.3 31.8 89.3 20.1 M M
24000 -26.8 -16.2 260 48 25 6.4 3.5 31.2 88.2 19.8 M M
23000 -25.2 -13.4 260 52 27 5.3 2.9 29.5 85.1 18.6 M M
22000 -23.7 -10.7 260 55 28 5.3 2.9 27.9 82.2 17.5 M M
21000 -22.0 -7.6 260 57 30 7.3 4.0 26.5 79.7 16.5 M M
20000 -19.8 -3.6 260 55 28 7.4 4.1 25.6 78.1 15.9 M M
19500 -18.7 -1.7 260 54 28 7.4 4.1 25.2 77.3 15.6 M M
19000 -17.6 0.3 260 52 27 7.5 4.1 24.8 76.7 15.3 M M
18500 -16.5 2.3 260 51 26 7.5 4.1 24.5 76.0 15.1 M M
18000 -15.4 4.3 260 50 26 7.5 4.1 24.1 75.3 14.8 M M
17500 -14.3 6.3 260 49 25 7.5 4.1 23.7 74.6 14.5 M M
17000 -13.2 8.2 260 48 24 7.6 4.2 23.3 73.9 14.2 M M
16500 -12.1 10.2 260 46 24 7.7 4.2 22.9 73.3 14.0 M M
16000 -11.0 12.2 260 45 23 7.4 4.1 22.6 72.6 13.7 M M
15500 -9.9 14.2 265 44 22 7.4 4.1 22.2 71.9 13.4 M M
15000 -8.8 16.2 265 42 22 7.5 4.1 21.8 71.2 13.1 M M
14500 -7.1 19.2 270 42 22 7.6 4.2 21.2 70.2 12.7 M M
14000 -6.0 21.2 270 41 21 7.7 4.2 20.9 69.6 12.4 M M
13500 -4.9 23.2 275 40 21 7.7 4.2 20.5 69.0 12.1 M M
13000 -3.7 25.3 275 39 20 7.4 4.1 20.2 68.4 11.9 M M
12500 -2.7 27.1 275 38 19 7.3 4.0 19.8 67.7 11.6 M M
12000 -1.6 29.1 275 36 18 6.8 3.7 19.4 66.9 11.2 M M
11500 -0.7 30.7 275 33 17 6.5 3.6 18.9 66.0 10.8 M M
11000 0.2 32.4 275 30 15 3.4 1.8 18.3 64.9 10.2 M M
10500 0.5 32.9 275 27 14 2.0 1.1 17.0 62.6 9.1 M M
10250 0.6 33.1 275 25 13 1.5 0.8 16.4 61.4 8.5 M M
10000 0.6 33.1 275 24 12 -1.1 -0.6 15.6 60.1 7.8 M M
9750 0.4 32.7 275 23 12 -3.2 -1.7 14.7 58.4 6.9 M M
9500 0.2 32.4 275 20 10 -2.9 -1.6 13.6 56.6 6.0 M M
9250 -0.0 32.0 280 18 9 -3.3 -1.8 12.7 54.8 5.0 M M
9000 -0.3 31.5 280 16 8 -4.1 -2.2 11.6 52.9 4.1 M M
8750 -0.7 30.7 275 14 7 -6.9 -3.8 10.4 50.8 3.0 M M
8500 -1.4 29.5 275 11 6 -10.8 -5.9 9.0 48.2 1.5 M M
8250 -2.0 28.4 270 9 5 -3.4 -1.9 7.5 45.6 0.2 M M
8000 -1.9 28.6 265 8 4 2.0 1.1 6.9 44.4 -0.5 298 1.5
7750 -1.8 28.8 255 7 4 3.4 1.9 6.2 43.2 -1.1 287 1.5
7500 -1.3 29.7 240 7 4 6.6 3.6 6.0 42.7 -1.4 266 1.3
7250 -0.9 30.4 215 8 4 4.8 2.6 5.6 42.1 -1.7 246 1.2
7000 -0.6 30.9 195 9 5 5.0 2.7 5.2 41.4 -2.1 227 1.2
6750 -0.2 31.6 180 12 6 4.1 2.2 4.9 40.8 -2.4 209 1.1
6500 0.1 32.2 175 14 7 4.0 2.2 4.4 39.9 -2.9 193 1.0
6250 0.4 32.7 170 12 6 4.9 2.7 4.0 39.2 -3.3 176 0.9
6000 0.8 33.4 160 10 5 4.4 2.4 3.6 38.5 -3.7 158 0.8
5750 1.1 34.0 150 8 4 5.5 3.0 3.3 37.9 -4.1 141 0.7
5500 1.6 34.9 135 6 3 8.1 4.4 3.0 37.4 -4.4 119 0.6
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/19/2024 at 0900 MDT | 04/19/2024 at 1200 MDT
|
CAPE... +1.3 LI... +1.2 | CAPE... +12.2 LI... +0.9
CINH... 0.0 K Index... +19.0 | CINH... 0.0 K Index... +19.1
|
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 -58.3 -72.9 265 53 27 2.1 1.2 | -56.7 -70.1 270 51 26 1.0 0.5
45000 -55.2 -67.4 260 66 34 -2.3 -1.3 | -55.4 -67.7 260 64 33 -2.4 -1.3
40000 -58.5 -73.3 260 70 36 -2.2 -1.2 | -59.3 -74.7 255 70 36 -2.6 -1.5
38000 -57.3 -71.1 260 68 35 5.0 2.7 | -57.9 -72.2 255 71 37 6.0 3.3
36000 -54.4 -65.9 260 65 33 5.0 2.7 | -54.2 -65.6 255 70 36 6.0 3.3
34000 -51.1 -60.0 260 61 31 6.8 3.7 | -50.6 -59.1 255 68 35 6.5 3.6
32000 -46.5 -51.7 260 56 29 6.8 3.7 | -46.2 -51.2 255 58 30 6.5 3.6
30000 -42.0 -43.6 260 54 28 8.8 4.9 | -42.0 -43.6 255 53 27 8.1 4.4
29000 -39.4 -38.9 260 55 28 8.8 4.8 | -39.5 -39.1 255 54 28 8.1 4.4
28000 -36.7 -34.1 260 56 29 8.9 4.9 | -37.1 -34.8 255 55 28 8.1 4.4
27000 -34.1 -29.4 260 56 29 8.0 4.4 | -34.7 -30.5 260 56 29 8.6 4.7
26000 -31.8 -25.2 260 54 28 8.0 4.4 | -32.1 -25.8 260 57 29 8.7 4.8
25000 -29.4 -20.9 260 53 27 8.0 4.4 | -29.5 -21.1 260 58 30 8.7 4.8
24000 -27.0 -16.6 260 51 26 7.0 3.8 | -26.9 -16.4 265 59 30 7.6 4.1
23000 -25.1 -13.2 260 52 27 6.3 3.4 | -25.0 -13.0 265 58 30 6.3 3.5
22000 -23.3 -9.9 260 53 27 6.3 3.4 | -23.1 -9.6 265 57 29 6.3 3.5
21000 -21.4 -6.5 260 54 28 6.3 3.5 | -21.3 -6.3 270 57 29 5.7 3.1
20000 -19.5 -3.1 260 54 28 6.3 3.5 | -19.6 -3.3 270 55 29 5.5 3.0
19500 -18.6 -1.5 260 53 28 6.3 3.5 | -18.8 -1.8 270 55 28 5.6 3.0
19000 -17.6 0.3 260 53 27 6.3 3.5 | -18.0 -0.4 270 54 28 5.6 3.1
18500 -16.7 1.9 260 53 27 7.1 3.9 | -17.2 1.0 270 54 28 6.1 3.4
18000 -15.6 3.9 260 51 26 7.4 4.1 | -16.2 2.8 270 51 26 6.5 3.6
17500 -14.5 5.9 260 49 25 7.4 4.0 | -15.3 4.5 265 48 25 6.6 3.6
17000 -13.5 7.7 265 47 24 6.2 3.4 | -13.7 7.3 265 45 23 7.6 4.2
16500 -12.6 9.3 265 46 24 6.3 3.5 | -12.6 9.3 265 43 22 7.7 4.2
16000 -11.7 10.9 265 45 23 6.7 3.7 | -11.4 11.5 270 43 22 7.9 4.3
15500 -10.7 12.7 270 44 22 6.7 3.7 | -10.3 13.5 270 43 22 8.0 4.4
15000 -9.2 15.4 275 42 22 6.3 3.4 | -9.2 15.4 270 41 21 7.1 3.9
14500 -8.3 17.1 280 41 21 6.2 3.4 | -8.2 17.2 270 37 19 7.2 3.9
14000 -7.3 18.9 280 40 21 7.3 4.0 | -7.1 19.2 265 33 17 7.3 4.0
13500 -6.3 20.7 280 39 20 7.4 4.0 | -6.0 21.2 265 30 16 7.4 4.0
13000 -5.2 22.6 285 38 19 7.8 4.3 | -5.0 23.0 265 28 14 6.6 3.6
12500 -4.0 24.8 285 36 19 7.9 4.3 | -4.0 24.8 265 24 12 6.3 3.5
12000 -2.9 26.8 285 34 18 7.8 4.3 | -3.2 26.2 265 20 10 4.7 2.6
11500 -1.7 28.9 280 32 17 7.9 4.3 | -2.6 27.3 265 17 9 3.7 2.0
11000 -0.7 30.7 280 30 15 5.2 2.9 | -2.1 28.2 265 14 7 1.4 0.8
10500 -0.1 31.8 285 26 14 4.4 2.4 | -2.1 28.2 270 11 6 0.1 0.0
10250 0.2 32.4 285 25 13 3.4 1.8 | -2.1 28.2 275 9 5 0.1 0.1
10000 0.3 32.5 285 24 12 -0.4 -0.2 | -2.1 28.2 275 8 4 -1.2 -0.6
9750 0.2 32.4 290 22 11 -2.5 -1.3 | -2.3 27.9 285 7 4 -3.2 -1.7
9500 0.0 32.0 290 19 10 -1.8 -1.0 | -2.6 27.3 305 5 3 -3.8 -2.1
9250 -0.2 31.6 300 17 9 -3.1 -1.7 | -2.8 27.0 335 5 3 -2.5 -1.4
9000 -0.5 31.1 305 15 8 -5.2 -2.9 | -2.9 26.8 355 5 3 -0.2 -0.1
8750 -0.9 30.4 310 13 7 -6.4 -3.5 | -2.9 26.8 005 6 3 -0.1 -0.0
8500 -1.4 29.5 320 12 6 -7.6 -4.2 | -2.9 26.8 015 6 3 -0.5 -0.3
8250 -1.9 28.6 330 11 6 -4.1 -2.3 | -2.9 26.8 025 7 3 -0.2 -0.1
8000 -2.1 28.2 335 10 5 -1.2 -0.7 | -3.0 26.6 020 7 4 -0.4 -0.2
7750 -2.2 28.0 340 9 5 -2.2 -1.2 | -3.0 26.6 020 8 4 0.8 0.4
7500 -2.3 27.9 340 8 4 0.6 0.3 | -2.8 27.0 010 8 4 4.7 2.6
7250 -2.1 28.2 340 6 3 4.8 2.6 | -2.3 27.9 005 9 5 8.5 4.7
7000 -1.6 29.1 335 5 2 5.4 3.0 | -1.6 29.1 005 9 5 10.1 5.6
6750 -1.2 29.8 325 3 2 6.4 3.5 | -0.9 30.4 360 9 5 8.7 4.8
6500 -0.7 30.7 290 1 1 8.2 4.5 | -0.3 31.5 355 10 5 9.4 5.2
6250 -0.0 32.0 320 1 1 8.5 4.6 | 0.5 32.9 355 9 5 11.3 6.2
6000 0.6 33.1 345 1 1 7.6 4.2 | 1.3 34.3 355 9 5 9.9 5.4
5750 1.2 34.2 360 2 1 10.9 6.0 | 2.1 35.8 350 9 5 13.7 7.5
5500 2.3 36.1 005 2 1 18.9 10.4 | 3.5 38.3 350 9 5 22.9 12.5
04/19/2024 at 1500 MDT | 04/19/2024 at 1800 MDT
|
CAPE... +19.3 LI... +4.1 | CAPE... +18.6 LI... +5.6
CINH... 0.0 K Index... +16.9 | CINH... 0.0 K Index... +16.1
|
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 -56.6 -69.9 260 44 23 1.0 0.5 | -56.3 -69.3 265 42 22 1.2 0.7
45000 -55.2 -67.4 260 59 30 -1.1 -0.6 | -54.6 -66.3 260 56 29 -1.5 -0.8
40000 -57.1 -70.8 255 70 36 -1.2 -0.7 | -57.3 -71.1 260 73 38 -1.8 -1.0
38000 -56.2 -69.2 255 72 37 3.5 1.9 | -56.9 -70.4 260 76 39 2.7 1.5
36000 -54.1 -65.4 255 72 37 3.5 1.9 | -55.3 -67.5 260 74 38 2.7 1.5
34000 -51.1 -60.0 255 70 36 6.8 3.7 | -53.2 -63.8 260 71 37 7.3 4.0
32000 -47.0 -52.6 260 66 34 6.8 3.7 | -48.4 -55.1 260 66 34 7.0 3.8
30000 -42.6 -44.7 260 63 32 8.3 4.6 | -43.7 -46.7 260 62 32 9.5 5.2
29000 -40.1 -40.2 265 63 32 8.3 4.6 | -40.9 -41.6 260 61 31 9.5 5.2
28000 -37.6 -35.7 265 62 32 8.3 4.6 | -38.1 -36.6 255 59 30 9.5 5.2
27000 -35.1 -31.2 265 62 32 8.1 4.4 | -35.3 -31.5 255 57 30 8.2 4.5
26000 -32.8 -27.0 265 62 32 8.0 4.4 | -32.9 -27.2 255 56 29 8.1 4.4
25000 -30.4 -22.7 265 62 32 8.0 4.4 | -30.5 -22.9 255 55 28 8.1 4.4
24000 -28.0 -18.4 265 62 32 7.3 4.0 | -28.1 -18.6 255 53 27 8.1 4.4
23000 -26.0 -14.8 265 60 31 6.5 3.6 | -25.7 -14.3 255 53 27 8.1 4.4
22000 -24.1 -11.4 265 58 30 6.5 3.6 | -23.3 -9.9 260 52 27 8.1 4.4
21000 -22.1 -7.8 265 57 29 7.3 4.0 | -20.9 -5.6 260 52 27 6.7 3.7
20000 -20.0 -4.0 265 55 29 7.4 4.1 | -19.0 -2.2 260 52 27 6.6 3.6
19500 -18.9 -2.0 265 55 28 7.4 4.1 | -18.0 -0.4 265 51 26 6.6 3.6
19000 -17.8 -0.0 265 54 28 7.4 4.1 | -17.0 1.4 265 51 26 6.6 3.6
18500 -16.7 1.9 265 54 28 7.6 4.2 | -16.0 3.2 265 51 26 7.0 3.9
18000 -15.5 4.1 265 52 27 7.7 4.2 | -14.9 5.2 265 50 26 7.3 4.0
17500 -13.9 7.0 260 49 25 7.4 4.1 | -13.9 7.0 265 49 25 7.3 4.0
17000 -12.8 9.0 260 46 23 7.2 4.0 | -12.3 9.9 270 45 23 6.9 3.8
16500 -11.8 10.8 260 42 22 7.3 4.0 | -11.3 11.7 270 43 22 6.9 3.8
16000 -10.7 12.7 260 39 20 7.5 4.1 | -10.4 13.3 270 38 20 6.6 3.6
15500 -9.6 14.7 260 35 18 7.5 4.1 | -9.4 15.1 270 34 17 6.8 3.7
15000 -8.5 16.7 260 32 17 8.0 4.4 | -8.6 16.5 270 29 15 5.2 2.8
14500 -7.3 18.9 260 29 15 8.1 4.5 | -7.8 18.0 270 24 12 5.5 3.0
14000 -6.2 20.8 260 26 14 5.6 3.1 | -7.2 19.0 265 20 10 3.1 1.7
13500 -5.5 22.1 255 24 12 5.2 2.9 | -6.7 19.9 260 18 9 2.8 1.6
13000 -4.8 23.4 255 21 11 2.1 1.1 | -6.4 20.5 255 16 8 2.2 1.2
12500 -4.8 23.4 255 18 9 0.6 0.3 | -6.1 21.0 250 15 8 2.0 1.1
12000 -4.7 23.5 250 15 8 -0.1 -0.1 | -5.8 21.6 240 14 7 1.8 1.0
11500 -4.8 23.4 240 11 6 -0.6 -0.3 | -5.5 22.1 225 13 7 1.7 0.9
11000 -4.9 23.2 225 8 4 0.8 0.5 | -5.3 22.5 210 13 7 1.5 0.8
10500 -4.6 23.7 220 6 3 1.7 1.0 | -5.0 23.0 210 11 6 1.5 0.8
10250 -4.5 23.9 215 4 2 1.4 0.8 | -4.9 23.2 210 10 5 1.3 0.7
10000 -4.4 24.1 205 4 2 -0.2 -0.1 | -4.9 23.2 205 9 5 0.5 0.3
9750 -4.5 23.9 185 3 1 -0.7 -0.4 | -4.8 23.4 200 8 4 0.3 0.2
9500 -4.5 23.9 155 2 1 -0.6 -0.3 | -4.8 23.4 185 6 3 0.2 0.1
9250 -4.5 23.9 125 3 2 0.2 0.1 | -4.8 23.4 160 4 2 0.6 0.3
9000 -4.4 24.1 100 3 2 1.8 1.0 | -4.7 23.5 140 3 2 0.9 0.5
8750 -4.3 24.3 075 4 2 2.4 1.3 | -4.6 23.7 115 2 1 1.8 1.0
8500 -4.1 24.6 050 5 3 2.1 1.1 | -4.4 24.1 065 2 1 2.7 1.5
8250 -3.9 25.0 035 7 4 5.2 2.9 | -4.2 24.4 045 3 2 3.6 2.0
8000 -3.4 25.9 025 9 5 7.9 4.3 | -3.9 25.0 040 5 2 4.0 2.2
7750 -2.8 27.0 020 11 6 7.5 4.1 | -3.6 25.5 035 6 3 4.8 2.6
7500 -2.2 28.0 015 12 6 8.6 4.7 | -3.2 26.2 040 7 4 6.3 3.5
7250 -1.6 29.1 015 13 6 9.3 5.1 | -2.7 27.1 040 8 4 6.7 3.7
7000 -0.9 30.4 010 13 7 9.6 5.3 | -2.3 27.9 040 9 5 6.5 3.6
6750 -0.2 31.6 005 13 7 9.0 4.9 | -1.8 28.8 040 11 5 7.3 4.0
6500 0.4 32.7 005 13 7 9.3 5.1 | -1.2 29.8 035 11 6 9.0 5.0
6250 1.2 34.2 005 13 6 10.6 5.8 | -0.5 31.1 035 10 5 9.6 5.3
6000 2.0 35.6 005 12 6 9.2 5.1 | 0.2 32.4 035 10 5 9.4 5.1
5750 2.7 36.9 005 12 6 13.3 7.3 | 0.9 33.6 035 9 5 11.9 6.5
5500 4.0 39.2 005 11 6 21.9 12.0 | 2.0 35.6 030 8 4 16.3 9.0
________________________________________________________________________________
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.
042613
- National Weather Service
- Quad Cities, IA/IL Weather Forecast Office
- 9040 N Harrison Street
- Davenport Municipal Airport
- Davenport, IA 52806-7326
- 563-386-3976
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- Page last modified: Sep 19th, 2023 19:10 UTC