Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
684
UXUS97 KBOU 290043
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1843 MDT Friday, June 28, 2024
This forecast is for Saturday, June 29, 2024:
If the trigger temperature of 69.0 F/20.5 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 369 ft/min (1.9 m/s)
Maximum height of thermals.................. 11935 ft MSL (6626 ft AGL)
Forecast maximum temperature................... 83.0 F/28.8 C
Time of trigger temperature.................... 1045 MDT
Time of overdevelopment........................ 1600 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 10766 ft MSL (5457 ft AGL)
Thermal soaring outlook for Sunday 06/30....... Good
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....................... 46860 ft MSL (41551 ft AGL)
Wave soaring outlook for Sunday 06/30.......... Poor
Remarks...
Sunrise/Sunset.................... 05:34:38 / 20:31:39 MDT
Total possible sunshine........... 14 hr 57 min 1 sec (897 min 1 sec)
Altitude of sun at 13:03:08 MDT... 73.38 degrees
Upper air data from numerical model forecast valid on 06/29/2024 at 0600 MDT
Freezing level.................. 15793 ft MSL (10484 ft AGL)
Convective condensation level... 16783 ft MSL (11474 ft AGL)
Lifted condensation level....... 15345 ft MSL (10036 ft AGL)
Lifted index.................... +2.7
K index......................... +16.6
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 -64.1 -83.4 270 57 30 0.8 0.5 M M M M M
45000 -60.4 -76.7 265 67 35 5.3 2.9 M M M M M
40000 -52.0 -61.6 265 57 29 7.4 4.1 M M M M M
38000 -47.6 -53.7 265 50 26 7.4 4.1 M M M M M
36000 -43.1 -45.6 265 43 22 7.5 4.1 M M M M M
34000 -38.3 -36.9 270 40 21 8.0 4.4 M M M M M
32000 -33.6 -28.5 270 37 19 8.0 4.4 M M M M M
30000 -28.3 -18.9 270 36 19 7.8 4.3 48.1 118.5 15.0 M M
29000 -26.0 -14.8 270 37 19 7.8 4.3 47.4 117.3 14.7 M M
28000 -23.6 -10.5 270 36 19 7.9 4.3 46.7 116.1 14.3 M M
27000 -21.3 -6.3 275 35 18 7.9 4.3 45.9 114.6 13.9 M M
26000 -18.9 -2.0 275 34 18 7.9 4.3 45.2 113.4 13.5 M M
25000 -16.5 2.3 280 34 17 6.9 3.8 44.7 112.4 13.2 M M
24000 -15.1 4.8 275 32 17 4.8 2.6 42.8 109.0 11.8 M M
23000 -13.7 7.3 270 32 16 4.9 2.7 41.0 105.7 10.3 M M
22000 -12.3 9.9 265 31 16 5.4 3.0 39.3 102.8 9.0 M M
21000 -10.6 12.9 265 29 15 6.0 3.3 37.9 100.2 7.8 M M
20000 -8.8 16.2 270 28 14 6.0 3.3 36.6 97.9 6.8 M M
19500 -7.9 17.8 270 27 14 6.0 3.3 36.0 96.8 6.3 M M
19000 -7.0 19.4 270 27 14 6.5 3.6 35.4 95.7 5.8 M M
18500 -6.1 21.0 270 26 14 6.6 3.6 34.8 94.7 5.3 M M
18000 -5.1 22.8 275 26 13 6.9 3.8 34.3 93.8 4.8 M M
17500 -4.1 24.6 275 26 13 7.4 4.1 33.9 93.0 4.4 M M
17000 -3.0 26.6 275 25 13 7.4 4.1 33.5 92.3 4.0 M M
16500 -1.9 28.6 275 24 12 7.9 4.3 33.1 91.6 3.7 M M
16000 -0.2 31.6 270 23 12 7.9 4.3 32.7 90.8 3.2 M M
15500 1.0 33.8 270 23 12 8.7 4.8 32.4 90.4 3.0 M M
15000 2.3 36.1 265 22 11 8.7 4.8 32.2 90.0 2.8 M M
14500 3.5 38.3 265 22 11 8.0 4.4 32.0 89.6 2.6 M M
14000 4.6 40.3 260 21 11 7.9 4.3 31.7 89.1 2.3 M M
13500 5.8 42.4 255 20 10 7.1 3.9 31.4 88.5 2.0 M M
13000 6.7 44.1 250 19 10 6.5 3.6 30.9 87.6 1.4 M M
12500 7.6 45.7 245 18 9 5.4 3.0 30.4 86.7 0.9 M M
12000 8.2 46.8 240 16 8 3.9 2.1 29.5 85.0 0.0 M M
11500 8.7 47.7 240 14 7 2.3 1.3 28.5 83.4 -0.9 338 1.7
11000 8.7 47.7 240 11 6 -1.0 -0.6 26.9 80.5 -2.4 324 1.6
10500 8.6 47.5 245 8 4 -1.3 -0.7 25.3 77.5 -3.9 313 1.6
10250 8.5 47.3 245 7 4 -1.5 -0.8 24.4 75.8 -4.8 309 1.6
10000 8.4 47.1 245 6 3 0.5 0.2 23.5 74.4 -5.6 303 1.5
9750 8.5 47.3 250 4 2 1.6 0.9 22.9 73.2 -6.3 294 1.5
9500 8.5 47.3 255 1 1 1.1 0.6 22.2 72.0 -7.0 285 1.4
9250 8.6 47.5 000 0 0 0.9 0.5 21.5 70.7 -7.7 277 1.4
9000 8.6 47.5 095 2 1 0.8 0.4 20.8 69.5 -8.4 269 1.4
8750 8.6 47.5 085 4 2 0.3 0.2 20.1 68.2 -9.2 263 1.3
8500 8.6 47.5 080 6 3 1.6 0.9 19.4 66.9 -9.9 255 1.3
8250 8.8 47.8 070 7 4 2.5 1.4 18.8 65.9 -10.4 239 1.2
8000 9.1 48.4 065 8 4 3.3 1.8 18.3 64.9 -10.9 224 1.1
7750 9.5 49.1 060 8 4 6.5 3.6 17.9 64.3 -11.2 204 1.0
7500 10.1 50.2 050 9 4 6.7 3.7 17.7 63.9 -11.4 179 0.9
7250 10.5 50.9 045 9 4 5.5 3.0 17.4 63.4 -11.7 158 0.8
7000 11.0 51.8 035 9 5 6.1 3.3 17.1 62.8 -12.0 137 0.7
6750 11.5 52.7 030 10 5 7.3 4.0 16.9 62.4 -12.2 114 0.6
6500 12.1 53.8 025 9 5 7.7 4.2 16.7 62.1 -12.4 90 0.5
6250 12.6 54.7 020 9 5 7.7 4.2 16.6 61.8 -12.7 66 0.3
6000 13.2 55.8 010 9 4 6.6 3.6 16.4 61.5 -12.9 42 0.2
5750 13.6 56.5 005 8 4 5.8 3.2 16.1 61.0 -13.2 22 0.1
5500 14.1 57.4 360 5 3 8.0 4.4 15.9 60.6 -13.5 0 0.0
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/29/2024 at 0900 MDT | 06/29/2024 at 1200 MDT
|
CAPE... 0.0 LI... +0.2 | CAPE... +3.2 LI... -1.1
CINH... 0.0 K Index... +18.6 | CINH... -3.9 K Index... +22.3
|
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 -63.4 -82.1 280 55 28 0.8 0.4 | -63.2 -81.8 290 50 26 1.5 0.8
45000 -59.7 -75.5 275 68 35 5.4 3.0 | -58.7 -73.7 280 64 33 5.5 3.0
40000 -51.3 -60.3 265 62 32 6.5 3.6 | -50.2 -58.4 265 65 34 6.5 3.6
38000 -47.4 -53.3 260 50 26 6.5 3.6 | -46.3 -51.3 260 57 29 6.5 3.6
36000 -43.5 -46.3 255 38 20 6.7 3.7 | -42.4 -44.3 255 49 25 6.6 3.6
34000 -38.7 -37.7 250 36 18 8.1 4.4 | -37.8 -36.0 255 42 22 6.9 3.8
32000 -33.3 -27.9 250 34 17 8.1 4.5 | -33.6 -28.5 250 36 19 7.3 4.0
30000 -28.5 -19.3 255 31 16 7.9 4.3 | -28.8 -19.8 250 32 17 8.0 4.4
29000 -26.2 -15.2 260 31 16 7.9 4.3 | -26.4 -15.5 250 30 16 8.0 4.4
28000 -23.8 -10.8 260 30 15 7.4 4.1 | -24.1 -11.4 250 29 15 7.0 3.8
27000 -21.6 -6.9 265 29 15 7.5 4.1 | -21.9 -7.4 250 28 14 7.1 3.9
26000 -19.4 -2.9 265 28 14 7.5 4.1 | -19.8 -3.6 255 27 14 7.2 3.9
25000 -17.2 1.0 265 27 14 6.7 3.7 | -17.7 0.1 255 26 13 6.7 3.7
24000 -15.6 3.9 265 27 14 5.4 2.9 | -15.9 3.4 255 26 14 6.0 3.3
23000 -14.0 6.8 265 27 14 5.4 3.0 | -14.2 6.4 255 27 14 6.0 3.3
22000 -12.4 9.7 260 28 14 5.7 3.1 | -12.4 9.7 255 27 14 5.9 3.2
21000 -10.7 12.7 260 26 14 6.0 3.3 | -10.8 12.6 255 26 13 5.8 3.2
20000 -8.9 16.0 265 25 13 6.0 3.3 | -9.1 15.6 255 25 13 5.9 3.2
19500 -8.0 17.6 265 24 12 6.0 3.3 | -8.3 17.1 255 25 13 6.0 3.3
19000 -7.1 19.2 265 23 12 6.5 3.6 | -7.3 18.9 255 24 12 7.6 4.2
18500 -6.1 21.0 270 22 11 6.5 3.5 | -6.2 20.8 255 22 11 7.5 4.1
18000 -5.2 22.6 270 21 11 6.8 3.7 | -4.5 23.9 255 20 10 7.2 4.0
17500 -4.1 24.6 275 20 10 7.2 3.9 | -3.4 25.9 255 18 9 7.3 4.0
17000 -2.6 27.3 280 19 10 7.9 4.3 | -2.3 27.9 255 17 9 7.9 4.3
16500 -1.4 29.5 280 19 10 8.4 4.6 | -1.1 30.0 260 16 8 8.2 4.5
16000 -0.2 31.6 280 18 9 8.5 4.7 | 0.2 32.4 260 15 8 8.4 4.6
15500 1.1 34.0 275 18 9 9.0 4.9 | 1.5 34.7 260 14 7 9.2 5.0
15000 2.4 36.3 270 18 9 9.0 5.0 | 2.8 37.0 260 14 7 9.2 5.0
14500 3.7 38.7 270 17 9 8.9 4.9 | 4.1 39.4 255 13 7 9.0 4.9
14000 5.0 41.0 265 17 9 9.0 4.9 | 5.4 41.7 255 13 7 9.1 5.0
13500 6.2 43.2 260 17 9 8.1 4.5 | 6.7 44.1 250 13 7 8.8 4.8
13000 7.3 45.1 255 17 9 7.8 4.3 | 8.0 46.4 245 13 7 8.8 4.8
12500 8.5 47.3 245 17 9 6.7 3.7 | 9.2 48.6 245 14 7 8.4 4.6
12000 9.3 48.7 240 17 9 5.7 3.1 | 10.4 50.7 240 15 8 8.2 4.5
11500 10.1 50.2 235 18 9 4.2 2.3 | 11.6 52.9 235 16 8 7.4 4.0
11000 10.4 50.7 230 17 9 2.2 1.2 | 12.5 54.5 230 17 9 6.5 3.5
10500 10.7 51.3 225 16 8 0.7 0.4 | 13.5 56.3 225 17 9 3.7 2.0
10250 10.7 51.3 225 15 8 -2.5 -1.4 | 13.5 56.3 225 18 9 -0.3 -0.1
10000 10.4 50.7 225 14 7 -4.9 -2.7 | 13.5 56.3 220 16 8 0.2 0.1
9750 9.9 49.8 220 12 6 -6.4 -3.5 | 13.5 56.3 220 15 8 0.1 0.0
9500 9.4 48.9 215 10 5 -5.8 -3.2 | 13.5 56.3 215 13 7 -0.8 -0.4
9250 9.0 48.2 210 9 5 -5.9 -3.2 | 13.3 55.9 210 12 6 -2.1 -1.1
9000 8.5 47.3 205 8 4 -5.1 -2.8 | 13.2 55.8 205 11 6 -0.2 -0.1
8750 8.1 46.6 190 6 3 -4.0 -2.2 | 13.3 55.9 195 9 5 1.1 0.6
8500 8.0 46.4 170 5 2 1.8 1.0 | 13.4 56.1 185 7 4 1.5 0.8
8250 8.4 47.1 155 4 2 5.8 3.2 | 13.5 56.3 165 7 3 0.8 0.5
8000 8.8 47.8 140 4 2 5.6 3.1 | 13.6 56.5 145 7 3 4.6 2.5
7750 9.4 48.9 130 5 2 8.1 4.4 | 14.2 57.6 135 7 3 10.0 5.5
7500 10.1 50.2 120 4 2 8.5 4.7 | 15.0 59.0 130 7 3 9.0 4.9
7250 10.7 51.3 115 4 2 6.9 3.8 | 15.5 59.9 130 7 3 6.7 3.7
7000 11.2 52.2 110 4 2 11.0 6.0 | 16.1 61.0 125 7 3 11.4 6.3
6750 12.2 54.0 095 3 2 12.4 6.8 | 17.2 63.0 120 6 3 13.0 7.1
6500 13.0 55.4 095 3 2 9.3 5.1 | 17.9 64.2 120 6 3 9.7 5.3
6250 13.7 56.7 090 3 2 10.8 5.9 | 18.7 65.7 115 6 3 11.2 6.1
6000 14.5 58.1 085 4 2 8.0 4.4 | 19.5 67.1 115 6 3 8.5 4.7
5750 15.1 59.2 085 3 2 11.8 6.5 | 20.2 68.4 110 6 3 15.0 8.3
5500 16.5 61.7 080 3 2 25.2 13.8 | 22.0 71.6 110 6 3 32.7 18.0
06/29/2024 at 1500 MDT | 06/29/2024 at 1800 MDT
|
CAPE... +64.5 LI... -1.6 | CAPE... +59.6 LI... -1.0
CINH... -14.8 K Index... +29.9 | CINH... -77.5 K Index... +30.1
|
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 -63.7 -82.7 285 44 22 1.6 0.9 | -64.3 -83.7 275 41 21 3.1 1.7
45000 -58.9 -74.0 280 57 29 5.9 3.2 | -58.1 -72.6 275 49 25 5.1 2.8
40000 -49.2 -56.6 270 61 31 7.2 3.9 | -49.8 -57.6 265 53 27 7.1 3.9
38000 -44.9 -48.8 265 60 31 7.2 3.9 | -45.6 -50.1 260 53 27 7.1 3.9
36000 -40.6 -41.1 260 59 30 6.8 3.7 | -41.3 -42.3 255 53 27 8.3 4.5
34000 -36.7 -34.1 255 51 26 6.5 3.6 | -36.0 -32.8 250 44 23 8.8 4.8
32000 -32.8 -27.0 250 43 22 6.9 3.8 | -30.1 -22.2 245 34 17 8.9 4.9
30000 -28.4 -19.1 250 38 20 7.3 4.0 | -25.6 -14.1 240 29 15 7.7 4.2
29000 -26.3 -15.3 250 36 18 7.3 4.0 | -23.3 -9.9 240 26 14 7.7 4.2
28000 -23.5 -10.3 250 34 17 7.6 4.2 | -21.2 -6.2 235 24 13 6.2 3.4
27000 -21.3 -6.3 250 32 17 7.7 4.2 | -19.3 -2.7 240 24 12 6.3 3.5
26000 -19.0 -2.2 255 31 16 7.8 4.3 | -17.5 0.5 240 23 12 6.3 3.5
25000 -16.8 1.8 260 30 15 7.1 3.9 | -15.6 3.9 240 22 11 6.5 3.6
24000 -14.8 5.4 255 28 14 6.9 3.8 | -13.7 7.3 240 21 11 6.6 3.6
23000 -12.8 9.0 255 26 13 7.0 3.8 | -11.8 10.8 240 20 10 6.6 3.6
22000 -10.8 12.6 255 24 12 5.8 3.2 | -9.9 14.2 235 19 10 6.0 3.3
21000 -9.2 15.4 250 21 11 5.6 3.1 | -8.2 17.2 235 18 9 5.8 3.2
20000 -7.6 18.3 245 19 10 5.7 3.1 | -6.6 20.1 235 18 9 5.8 3.2
19500 -6.8 19.8 240 17 9 5.9 3.3 | -5.7 21.7 235 17 9 5.8 3.2
19000 -5.8 21.6 240 16 8 6.7 3.7 | -4.9 23.2 230 17 9 5.7 3.1
18500 -4.9 23.2 235 15 8 6.7 3.7 | -4.1 24.6 230 16 8 5.7 3.1
18000 -3.9 25.0 235 14 7 6.5 3.5 | -3.3 26.1 230 15 8 5.7 3.1
17500 -3.0 26.6 230 13 7 6.4 3.5 | -2.5 27.5 230 15 8 5.7 3.1
17000 -2.1 28.2 225 12 6 6.5 3.6 | -1.3 29.7 225 13 7 5.5 3.0
16500 -1.1 30.0 225 11 6 6.7 3.7 | -0.5 31.1 220 13 7 5.4 2.9
16000 -0.1 31.8 220 10 5 6.7 3.7 | 0.3 32.5 215 12 6 5.3 2.9
15500 0.9 33.6 220 10 5 7.4 4.1 | 1.0 33.8 210 12 6 4.7 2.6
15000 2.0 35.6 215 10 5 7.4 4.1 | 1.7 35.1 205 12 6 4.5 2.5
14500 3.1 37.6 215 9 5 7.9 4.3 | 2.6 36.7 200 11 6 7.5 4.1
14000 4.2 39.6 210 9 5 8.1 4.4 | 3.6 38.5 195 11 6 7.3 4.0
13500 5.4 41.7 210 10 5 8.3 4.6 | 4.7 40.5 190 11 6 7.9 4.3
13000 7.3 45.1 205 10 5 8.7 4.8 | 5.9 42.6 185 11 6 8.1 4.4
12500 8.5 47.3 205 10 5 8.2 4.5 | 7.0 44.6 180 11 6 7.2 3.9
12000 9.7 49.5 205 10 5 8.1 4.5 | 7.9 46.2 175 11 6 6.7 3.7
11500 10.8 51.4 200 10 5 7.3 4.0 | 8.9 48.0 175 11 6 6.3 3.5
11000 11.9 53.4 195 10 5 7.1 3.9 | 9.7 49.5 175 11 6 5.9 3.2
10500 12.8 55.0 195 10 5 2.3 1.2 | 10.6 51.1 170 11 6 4.7 2.6
10250 12.8 55.0 190 10 5 2.2 1.2 | 10.9 51.6 170 11 6 4.7 2.6
10000 13.2 55.8 185 9 5 5.6 3.1 | 11.3 52.3 170 11 6 6.7 3.7
9750 13.6 56.5 175 9 4 4.7 2.6 | 11.8 53.2 165 11 6 6.9 3.8
9500 13.9 57.0 170 8 4 4.3 2.3 | 12.2 54.0 165 11 5 5.2 2.9
9250 14.2 57.6 160 7 4 4.4 2.4 | 12.5 54.5 165 10 5 3.3 1.8
9000 14.7 58.5 150 7 4 9.5 5.2 | 12.8 55.0 160 10 5 6.0 3.3
8750 15.5 59.9 145 7 4 11.3 6.2 | 13.3 55.9 155 9 5 7.6 4.2
8500 16.2 61.2 140 7 4 8.1 4.4 | 13.8 56.8 155 9 4 5.3 2.9
8250 16.8 62.2 140 7 4 6.2 3.4 | 14.1 57.4 150 8 4 4.0 2.2
8000 17.3 63.1 140 7 4 10.4 5.7 | 14.4 57.9 145 8 4 5.5 3.0
7750 18.3 64.9 140 7 4 12.1 6.6 | 14.8 58.6 140 7 3 6.0 3.3
7500 19.0 66.2 140 7 4 8.6 4.7 | 15.2 59.4 140 6 3 4.3 2.3
7250 19.6 67.3 135 7 3 7.5 4.1 | 15.5 59.9 140 5 2 3.4 1.9
7000 20.2 68.4 135 7 3 11.2 6.2 | 15.7 60.3 145 4 2 4.5 2.5
6750 21.2 70.2 135 7 3 12.4 6.8 | 16.1 61.0 145 3 1 5.4 3.0
6500 21.9 71.4 135 6 3 9.3 5.1 | 16.4 61.5 180 2 1 5.2 2.9
6250 22.7 72.9 135 6 3 10.8 5.9 | 16.8 62.2 220 2 1 5.3 2.9
6000 23.4 74.1 135 6 3 7.8 4.3 | 17.1 62.8 245 3 2 5.4 2.9
5750 24.0 75.2 135 6 3 12.4 6.8 | 17.6 63.7 250 4 2 9.8 5.4
5500 25.5 77.9 130 5 3 27.9 15.3 | 18.6 65.5 250 4 2 16.8 9.2
________________________________________________________________________________
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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