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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 151222
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0621 MDT Monday, April 15, 2024
This forecast is for Monday, April 15, 2024:
If the trigger temperature of 70.7 F/21.5 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 666 ft/min (3.4 m/s)
Maximum height of thermals.................. 12990 ft MSL (7690 ft AGL)
Forecast maximum temperature................... 74.0 F/23.8 C
Time of trigger temperature.................... 1130 MDT
Time of overdevelopment........................ 1900 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 6825 ft MSL (1525 ft AGL)
Thermal soaring outlook for Tuesday 04/16...... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT).........
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 32794 ft MSL (27494 ft AGL)
Wave soaring outlook for Tuesday 04/16......... Fair
Remarks...
Sunrise/Sunset.................... 06:20:35 / 19:38:03 MDT
Total possible sunshine........... 13 hr 17 min 28 sec (797 min 28 sec)
Altitude of sun at 12:59:19 MDT... 60.38 degrees
Upper air data from numerical model forecast valid on 04/15/2024 at 0600 MDT
Freezing level.................. 13116 ft MSL (7816 ft AGL)
Convective condensation level... 20082 ft MSL (14782 ft AGL)
Lifted condensation level....... 18318 ft MSL (13018 ft AGL)
Lifted index.................... +2.3
K index......................... -2.2
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 -55.7 -68.3 245 50 26 -0.3 -0.2 M M M M M
45000 -56.2 -69.2 235 67 35 -1.2 -0.7 M M M M M
40000 -58.7 -73.7 230 75 39 -1.6 -0.9 M M M M M
38000 -57.4 -71.3 230 75 39 4.3 2.4 M M M M M
36000 -54.8 -66.6 230 74 38 4.3 2.4 M M M M M
34000 -51.6 -60.9 225 72 37 7.8 4.3 M M M M M
32000 -46.9 -52.4 220 66 34 7.9 4.3 M M M M M
30000 -42.0 -43.6 215 61 31 8.5 4.7 33.3 92.0 7.5 M M
29000 -39.5 -39.1 215 58 30 8.5 4.7 32.7 90.9 7.2 M M
28000 -36.3 -33.3 210 55 28 8.5 4.7 32.2 90.0 6.9 M M
27000 -33.8 -28.8 210 53 27 8.3 4.6 31.8 89.3 6.6 M M
26000 -31.3 -24.3 205 50 26 8.3 4.6 31.2 88.1 6.2 M M
25000 -28.8 -19.8 200 48 25 8.3 4.6 30.7 87.2 5.9 M M
24000 -26.3 -15.3 200 46 24 8.8 4.8 30.3 86.5 5.6 M M
23000 -23.6 -10.5 195 43 22 8.9 4.9 29.9 85.7 5.4 M M
22000 -20.9 -5.6 190 41 21 8.9 4.9 29.6 85.2 5.2 M M
21000 -18.4 -1.1 190 39 20 7.6 4.2 29.2 84.6 4.9 M M
20000 -16.1 3.0 190 38 19 7.7 4.2 28.4 83.1 4.3 M M
19500 -14.9 5.2 190 37 19 7.7 4.2 28.1 82.5 4.0 M M
19000 -13.8 7.2 190 37 19 7.7 4.2 27.7 81.9 3.8 M M
18500 -12.6 9.3 190 36 19 7.4 4.1 27.4 81.3 3.5 M M
18000 -11.6 11.1 185 35 18 7.3 4.0 26.9 80.5 3.1 M M
17500 -10.5 13.1 185 33 17 7.3 4.0 26.5 79.8 2.8 M M
17000 -9.4 15.1 185 32 17 7.4 4.1 26.1 79.0 2.4 M M
16500 -8.3 17.1 185 32 16 7.4 4.0 25.7 78.3 2.1 M M
16000 -7.2 19.0 185 31 16 7.8 4.3 25.3 77.6 1.7 M M
15500 -6.0 21.2 185 30 15 7.9 4.3 25.0 77.0 1.4 M M
15000 -4.9 23.2 185 29 15 8.0 4.4 24.7 76.5 1.1 M M
14500 -3.1 26.4 190 28 14 8.2 4.5 24.3 75.7 0.8 M M
14000 -1.9 28.6 190 28 14 8.1 4.4 24.0 75.3 0.5 M M
13500 -0.7 30.7 195 28 14 8.0 4.4 23.8 74.8 0.2 M M
13000 0.5 32.9 200 28 15 8.0 4.4 23.5 74.3 -0.0 658 3.3
12500 1.7 35.1 205 28 15 8.1 4.4 23.2 73.8 -0.3 609 3.1
12000 2.8 37.0 205 29 15 8.1 4.4 22.9 73.3 -0.6 559 2.8
11500 4.0 39.2 210 28 15 8.1 4.4 22.7 72.8 -0.9 509 2.6
11000 5.2 41.4 215 28 15 8.0 4.4 22.4 72.4 -1.2 459 2.3
10500 6.3 43.3 220 28 14 7.2 3.9 22.1 71.8 -1.6 410 2.1
10250 6.9 44.4 225 27 14 9.4 5.2 21.9 71.5 -1.7 386 2.0
10000 7.7 45.9 225 27 14 10.8 5.9 22.0 71.7 -1.6 354 1.8
9750 8.4 47.1 225 26 13 9.0 4.9 22.0 71.6 -1.7 326 1.7
9500 9.1 48.4 230 25 13 9.1 5.0 22.0 71.5 -1.7 298 1.5
9250 9.7 49.5 230 24 12 8.4 4.6 21.9 71.4 -1.8 271 1.4
9000 10.3 50.5 235 24 12 8.0 4.4 21.8 71.2 -1.9 246 1.2
8750 10.9 51.6 235 22 12 8.9 4.9 21.7 71.0 -2.0 219 1.1
8500 11.6 52.9 240 21 11 9.2 5.1 21.6 70.9 -2.1 191 1.0
8250 12.3 54.1 240 20 10 9.2 5.0 21.6 70.8 -2.1 163 0.8
8000 13.0 55.4 245 18 9 9.4 5.2 21.5 70.8 -2.2 135 0.7
7750 13.7 56.7 245 18 9 8.6 4.7 21.5 70.7 -2.2 107 0.5
7500 14.3 57.7 245 18 9 7.9 4.3 21.3 70.4 -2.3 82 0.4
7250 14.9 58.8 245 17 9 7.8 4.3 21.2 70.2 -2.5 56 0.3
7000 15.5 59.9 250 16 8 6.0 3.3 21.0 69.8 -2.7 33 0.2
6750 15.8 60.4 250 15 8 2.1 1.2 20.6 69.1 -3.1 16 0.1
6500 15.9 60.6 255 13 7 3.6 2.0 20.0 68.0 -3.7 4 0.0
6250 16.0 60.8 255 12 6 -6.0 -3.3 19.4 66.9 -4.3 M M
6000 14.9 58.8 255 11 6 -17.6 -9.7 17.6 63.6 -6.1 18 0.1
5750 13.4 56.1 250 9 5 -27.0 -14.8 15.3 59.6 -8.4 57 0.3
5500 10.4 50.7 230 7 4 -50.8 -27.9 11.7 53.0 -12.2 141 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/15/2024 at 0900 MDT | 04/15/2024 at 1200 MDT
|
CAPE... 0.0 LI... +4.2 | CAPE... 0.0 LI... +2.7
CINH... 0.0 K Index... -1.2 | CINH... 0.0 K Index... -1.5
|
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 -53.7 -64.7 235 46 24 -0.8 -0.4 | -53.3 -63.9 240 44 23 0.3 0.2
45000 -54.8 -66.6 230 67 35 -1.2 -0.6 | -52.8 -63.0 230 68 35 -0.2 -0.1
40000 -57.2 -71.0 220 70 36 -1.5 -0.8 | -54.0 -65.2 210 68 35 -0.7 -0.4
38000 -56.3 -69.3 215 73 38 3.7 2.0 | -53.4 -64.1 205 70 36 2.6 1.4
36000 -54.1 -65.4 215 77 40 3.7 2.0 | -51.8 -61.2 205 72 37 2.6 1.4
34000 -51.5 -60.7 215 80 41 7.2 4.0 | -50.0 -58.0 205 75 39 6.4 3.5
32000 -47.2 -53.0 210 75 39 7.2 3.9 | -46.4 -51.5 200 78 40 6.0 3.3
30000 -42.8 -45.0 205 70 36 8.2 4.5 | -42.8 -45.0 200 80 41 7.5 4.1
29000 -39.7 -39.5 205 65 34 8.2 4.5 | -40.0 -40.0 200 76 39 7.3 4.0
28000 -37.2 -35.0 200 62 32 8.2 4.5 | -37.8 -36.0 195 74 38 7.3 4.0
27000 -34.8 -30.6 200 58 30 8.2 4.5 | -35.7 -32.3 195 71 37 7.1 3.9
26000 -32.3 -26.1 195 55 28 8.2 4.5 | -33.7 -28.7 190 68 35 6.6 3.6
25000 -29.9 -21.8 190 52 27 8.2 4.5 | -31.7 -25.1 190 64 33 6.6 3.6
24000 -27.4 -17.3 180 50 26 8.3 4.6 | -29.7 -21.5 185 61 31 6.6 3.6
23000 -24.9 -12.8 180 48 25 8.4 4.6 | -27.4 -17.3 185 60 31 7.8 4.3
22000 -22.4 -8.3 175 46 24 8.4 4.6 | -25.1 -13.2 185 59 31 7.9 4.3
21000 -19.9 -3.8 175 45 23 7.7 4.2 | -22.8 -9.0 185 59 30 8.0 4.4
20000 -17.7 0.1 175 43 22 7.5 4.1 | -20.3 -4.5 185 57 29 8.1 4.5
19500 -16.5 2.3 175 42 22 7.5 4.1 | -19.1 -2.4 185 56 29 8.1 4.5
19000 -15.4 4.3 180 42 21 7.5 4.1 | -17.9 -0.2 185 55 28 8.1 4.5
18500 -14.3 6.3 180 41 21 7.5 4.1 | -16.7 1.9 185 54 28 8.2 4.5
18000 -13.2 8.2 180 40 21 7.5 4.1 | -15.5 4.1 185 53 27 8.5 4.6
17500 -12.1 10.2 180 39 20 7.5 4.1 | -14.2 6.4 185 51 26 8.4 4.6
17000 -10.9 12.4 180 38 20 8.2 4.5 | -12.9 8.8 185 50 26 8.9 4.9
16500 -9.7 14.5 180 37 19 8.1 4.5 | -11.6 11.1 185 49 25 8.9 4.9
16000 -8.5 16.7 180 36 19 8.0 4.4 | -10.2 13.6 185 48 25 8.5 4.7
15500 -6.7 19.9 185 35 18 7.9 4.3 | -8.5 16.7 190 47 24 7.6 4.2
15000 -5.6 21.9 185 34 18 7.4 4.1 | -7.4 18.7 195 45 23 7.6 4.1
14500 -4.5 23.9 190 34 17 7.3 4.0 | -6.3 20.7 195 44 23 7.5 4.1
14000 -3.4 25.9 195 33 17 7.1 3.9 | -5.1 22.8 200 43 22 7.3 4.0
13500 -2.4 27.7 200 33 17 7.0 3.8 | -4.1 24.6 205 40 20 6.5 3.6
13000 -1.4 29.5 205 33 17 6.8 3.7 | -3.2 26.2 210 37 19 6.6 3.6
12500 -0.5 31.1 210 31 16 6.4 3.5 | -2.1 28.2 210 33 17 7.6 4.1
12000 0.4 32.7 215 29 15 6.7 3.7 | -1.0 30.2 215 29 15 7.5 4.1
11500 1.5 34.7 215 26 13 7.7 4.2 | 0.1 32.2 215 24 12 8.2 4.5
11000 2.6 36.7 220 22 11 7.8 4.3 | 1.3 34.3 215 20 10 8.2 4.5
10500 3.8 38.8 215 18 9 8.5 4.6 | 2.5 36.5 210 16 8 8.8 4.8
10250 4.5 40.1 215 15 8 8.9 4.9 | 3.2 37.8 205 14 7 8.9 4.9
10000 5.2 41.4 215 13 7 9.9 5.4 | 3.8 38.8 205 13 7 9.1 5.0
9750 5.9 42.6 210 12 6 10.3 5.7 | 4.5 40.1 205 12 6 10.1 5.5
9500 6.7 44.1 205 10 5 10.4 5.7 | 5.3 41.5 205 12 6 10.9 6.0
9250 7.5 45.5 205 8 4 10.5 5.8 | 6.1 43.0 205 12 6 10.4 5.7
9000 8.2 46.8 195 7 3 7.8 4.3 | 6.8 44.2 200 11 6 7.9 4.3
8750 8.7 47.7 195 6 3 6.6 3.6 | 7.4 45.3 200 11 6 9.3 5.1
8500 9.3 48.7 200 4 2 7.8 4.3 | 8.2 46.8 200 11 6 11.7 6.4
8250 9.9 49.8 210 3 1 7.9 4.4 | 9.1 48.4 200 11 6 12.2 6.7
8000 10.4 50.7 240 2 1 6.3 3.5 | 9.9 49.8 200 11 5 7.6 4.2
7750 10.8 51.4 290 3 2 3.6 2.0 | 10.3 50.5 200 10 5 6.6 3.6
7500 11.1 52.0 300 5 2 3.4 1.8 | 11.0 51.8 200 10 5 10.9 6.0
7250 11.3 52.3 300 6 3 3.6 2.0 | 11.8 53.2 200 10 5 9.2 5.1
7000 11.6 52.9 305 8 4 4.6 2.5 | 12.5 54.5 200 10 5 11.6 6.4
6750 12.0 53.6 305 10 5 3.6 2.0 | 13.5 56.3 205 10 5 11.2 6.2
6500 12.2 54.0 300 11 6 2.5 1.4 | 14.2 57.6 205 10 5 8.7 4.8
6250 12.3 54.1 300 12 6 2.2 1.2 | 14.9 58.8 205 9 5 10.0 5.5
6000 12.4 54.3 300 10 5 1.1 0.6 | 15.6 60.1 205 9 5 10.7 5.9
5750 12.5 54.5 295 7 3 2.3 1.3 | 16.6 61.9 205 9 5 17.0 9.3
5500 12.8 55.0 275 4 2 9.0 4.9 | 18.2 64.8 205 8 4 27.3 15.0
04/15/2024 at 1500 MDT | 04/15/2024 at 1800 MDT
|
CAPE... 0.0 LI... +1.8 | CAPE... +24.0 LI... +0.1
CINH... 0.0 K Index... -8.1 | CINH... -13.7 K Index... +11.8
|
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 -52.6 -62.7 245 45 23 1.5 0.8 | -51.8 -61.2 240 38 20 1.8 1.0
45000 -50.3 -58.5 235 56 29 0.6 0.3 | -49.1 -56.4 250 39 20 1.4 0.8
40000 -50.6 -59.1 210 59 30 -0.2 -0.1 | -47.8 -54.0 225 42 21 0.8 0.4
38000 -50.4 -58.7 205 59 30 0.9 0.5 | -47.7 -53.9 220 41 21 -0.3 -0.2
36000 -49.8 -57.6 200 56 29 0.9 0.5 | -47.9 -54.2 205 37 19 -0.3 -0.2
34000 -49.0 -56.2 195 53 28 6.0 3.3 | -48.1 -54.6 190 36 18 1.7 1.0
32000 -45.5 -49.9 195 55 29 5.8 3.2 | -45.7 -50.3 185 30 16 3.9 2.2
30000 -42.0 -43.6 200 57 29 5.8 3.2 | -43.4 -46.1 185 25 13 4.6 2.5
29000 -40.3 -40.5 195 57 29 5.8 3.2 | -41.7 -43.1 185 23 12 5.6 3.1
28000 -38.5 -37.3 195 56 29 5.8 3.2 | -40.1 -40.2 185 21 11 5.6 3.1
27000 -36.8 -34.2 195 56 29 5.8 3.2 | -38.0 -36.4 185 19 10 5.6 3.1
26000 -35.2 -31.4 195 52 27 5.2 2.8 | -36.3 -33.3 185 17 9 5.7 3.1
25000 -33.6 -28.5 195 47 24 5.2 2.8 | -34.6 -30.3 185 14 7 5.7 3.1
24000 -32.1 -25.8 190 43 22 5.2 2.8 | -32.9 -27.2 180 11 6 5.6 3.1
23000 -30.0 -22.0 190 40 20 7.8 4.3 | -31.0 -23.8 180 11 5 7.0 3.9
22000 -27.7 -17.9 190 38 19 7.9 4.3 | -28.9 -20.0 175 11 6 7.1 3.9
21000 -25.3 -13.5 185 36 19 7.8 4.3 | -26.8 -16.2 175 12 6 7.0 3.9
20000 -22.1 -7.8 185 35 18 8.7 4.8 | -24.4 -11.9 175 11 6 8.0 4.4
19500 -20.8 -5.4 185 35 18 8.7 4.8 | -23.2 -9.8 180 11 6 8.0 4.4
19000 -19.5 -3.1 190 34 18 8.7 4.8 | -22.1 -7.8 185 11 6 8.0 4.4
18500 -18.2 -0.8 190 34 18 8.7 4.8 | -20.9 -5.6 190 11 5 8.0 4.4
18000 -16.9 1.6 190 33 17 8.7 4.8 | -19.6 -3.3 195 11 6 8.3 4.6
17500 -15.6 3.9 190 33 17 8.7 4.8 | -18.4 -1.1 195 12 6 8.3 4.6
17000 -14.3 6.3 190 32 16 8.6 4.7 | -17.2 1.0 200 12 6 8.4 4.6
16500 -13.0 8.6 190 31 16 8.6 4.7 | -15.9 3.4 205 14 7 8.4 4.6
16000 -11.7 10.9 190 31 16 8.7 4.8 | -14.7 5.5 205 15 8 8.4 4.6
15500 -10.4 13.3 195 30 16 8.8 4.8 | -13.4 7.9 205 16 8 8.9 4.9
15000 -9.1 15.6 195 30 15 8.6 4.7 | -12.1 10.2 205 18 9 8.8 4.9
14500 -7.8 18.0 195 30 15 8.2 4.5 | -10.8 12.6 210 19 10 9.2 5.1
14000 -6.6 20.1 200 29 15 8.2 4.5 | -9.4 15.1 210 20 10 9.2 5.1
13500 -5.4 22.3 200 29 15 8.0 4.4 | -8.0 17.6 210 21 11 9.6 5.2
13000 -4.2 24.4 200 27 14 8.0 4.4 | -6.6 20.1 210 21 11 9.7 5.3
12500 -2.9 26.8 200 26 13 9.2 5.0 | -4.5 23.9 215 22 11 8.9 4.9
12000 -1.6 29.1 200 25 13 9.2 5.0 | -3.1 26.4 215 22 11 8.9 4.9
11500 -0.2 31.6 200 24 12 9.8 5.4 | -1.8 28.8 220 22 11 9.6 5.3
11000 1.2 34.2 205 23 12 9.7 5.3 | -0.4 31.3 220 22 11 9.8 5.4
10500 2.8 37.0 205 23 12 11.2 6.1 | 0.9 33.6 225 22 11 7.6 4.2
10250 3.6 38.5 205 23 12 10.0 5.5 | 1.5 34.7 230 22 11 8.6 4.7
10000 4.2 39.6 205 23 12 7.9 4.3 | 2.2 36.0 230 22 11 9.9 5.5
9750 4.9 40.8 205 23 12 9.8 5.4 | 3.0 37.4 235 22 12 9.5 5.2
9500 5.7 42.3 205 23 12 11.9 6.5 | 3.6 38.5 235 23 12 8.9 4.9
9250 6.6 43.9 205 23 12 12.0 6.6 | 4.3 39.7 240 23 12 9.1 5.0
9000 7.4 45.3 205 23 12 7.8 4.3 | 4.9 40.8 240 23 12 8.5 4.7
8750 7.9 46.2 205 23 12 8.5 4.7 | 5.6 42.1 245 23 12 8.8 4.8
8500 8.7 47.7 205 23 12 11.9 6.5 | 6.3 43.3 245 24 12 9.4 5.2
8250 9.6 49.3 205 23 12 12.1 6.6 | 7.0 44.6 245 24 12 9.4 5.1
8000 10.4 50.7 205 23 12 8.0 4.4 | 7.6 45.7 250 24 13 9.0 5.0
7750 10.9 51.6 205 23 12 7.1 3.9 | 8.3 46.9 250 24 13 9.4 5.2
7500 11.6 52.9 205 23 12 10.7 5.9 | 9.0 48.2 250 24 13 10.0 5.5
7250 12.4 54.3 205 23 12 9.7 5.3 | 9.8 49.6 250 24 13 10.1 5.5
7000 13.1 55.6 205 22 12 10.1 5.6 | 10.5 50.9 250 24 13 8.9 4.9
6750 13.9 57.0 205 22 11 10.3 5.7 | 11.2 52.2 250 24 12 9.2 5.1
6500 14.7 58.5 205 22 11 10.3 5.7 | 11.9 53.4 250 24 12 10.6 5.8
6250 15.4 59.7 205 22 11 10.3 5.7 | 12.7 54.9 250 24 12 10.3 5.7
6000 16.2 61.2 210 21 11 10.7 5.9 | 13.5 56.3 250 23 12 9.9 5.4
5750 17.2 63.0 210 20 11 17.5 9.6 | 14.2 57.6 250 22 11 12.5 6.9
5500 18.9 66.0 210 19 10 27.6 15.2 | 15.4 59.7 250 20 10 18.3 10.0
________________________________________________________________________________
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
- Western and Central Wyoming Weather Forecast Office
- 12744 West U.S. Hwy 26
- Riverton, WY 82501
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- Page last modified: Sep 19th, 2023 19:10 UTC