Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
358
UXUS97 KBOU 170015
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1815 MDT Sunday, June 16, 2024
This forecast is for Monday, June 17, 2024:
If the trigger temperature of 86.8 F/30.4 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1688 ft/min (8.6 m/s)
Maximum height of thermals.................. 22135 ft MSL (16864 ft AGL)
Forecast maximum temperature................... 95.0 F/35.5 C
Time of trigger temperature.................... 1245 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 15452 ft MSL (10181 ft AGL)
Thermal soaring outlook for Tuesday 06/18...... Poor
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)................ Neither
Potential height of wave....................... 46346 ft MSL (41075 ft AGL)
Wave soaring outlook for Tuesday 06/18......... Fair
Remarks...
Sunrise/Sunset.................... 05:31:03 / 20:30:08 MDT
Total possible sunshine........... 14 hr 59 min 5 sec (899 min 5 sec)
Altitude of sun at 13:00:36 MDT... 73.64 degrees
Upper air data from numerical model forecast valid on 06/17/2024 at 0600 MDT
Freezing level.................. 15952 ft MSL (10681 ft AGL)
Convective condensation level... 19174 ft MSL (13903 ft AGL)
Lifted condensation level....... 19992 ft MSL (14721 ft AGL)
Lifted index.................... -2.5
K index......................... +6.5
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 -60.6 -77.1 245 39 20 2.3 1.3 M M M M M
45000 -57.2 -71.0 250 46 24 2.3 1.3 M M M M M
40000 -53.3 -63.9 240 35 18 5.8 3.2 M M M M M
38000 -49.7 -57.5 240 34 17 5.9 3.3 M M M M M
36000 -46.2 -51.2 240 33 17 6.0 3.3 M M M M M
34000 -42.1 -43.8 240 31 16 7.2 3.9 M M M M M
32000 -37.8 -36.0 235 30 15 7.2 3.9 M M M M M
30000 -33.5 -28.3 235 29 15 7.3 4.0 42.4 108.2 5.6 M M
29000 -30.8 -23.4 230 29 15 7.3 4.0 41.2 106.1 4.7 M M
28000 -28.6 -19.5 230 29 15 7.3 4.0 40.4 104.6 4.2 M M
27000 -26.3 -15.3 230 29 15 7.5 4.1 39.4 102.9 3.5 M M
26000 -24.1 -11.4 225 28 15 7.6 4.1 38.5 101.4 2.8 M M
25000 -21.8 -7.2 225 28 14 7.6 4.2 37.8 100.1 2.2 M M
24000 -19.6 -3.3 230 28 14 7.1 3.9 36.9 98.4 1.5 M M
23000 -17.5 0.5 230 28 15 7.2 3.9 35.9 96.6 0.7 M M
22000 -15.4 4.3 230 28 15 7.2 3.9 35.0 95.1 -0.1 1675 8.5
21000 -13.1 8.4 235 29 15 8.3 4.6 34.4 93.9 -0.7 1575 8.0
20000 -10.6 12.9 235 29 15 8.3 4.6 33.9 92.9 -1.2 1471 7.5
19500 -9.3 15.3 240 30 15 8.4 4.6 33.6 92.6 -1.4 1419 7.2
19000 -8.1 17.4 240 30 15 8.6 4.7 33.4 92.2 -1.5 1366 6.9
18500 -6.7 19.9 240 30 16 9.2 5.1 33.3 92.0 -1.7 1311 6.7
18000 -5.4 22.3 240 30 16 9.3 5.1 33.2 91.8 -1.8 1255 6.4
17500 -4.0 24.8 240 30 15 8.5 4.6 33.1 91.6 -1.9 1200 6.1
17000 -2.8 27.0 240 29 15 8.4 4.6 32.9 91.1 -2.1 1148 5.8
16500 -1.5 29.3 235 29 15 8.3 4.5 32.6 90.8 -2.3 1096 5.6
16000 -0.3 31.5 235 27 14 8.1 4.4 32.4 90.2 -2.6 1045 5.3
15500 0.8 33.4 235 26 13 8.0 4.4 32.1 89.7 -2.9 995 5.1
15000 2.1 35.8 235 24 12 9.1 5.0 31.9 89.4 -3.1 943 4.8
14500 3.4 38.1 235 22 11 9.0 4.9 31.7 89.1 -3.3 888 4.5
14000 5.4 41.7 235 20 10 9.1 5.0 31.6 88.8 -3.5 806 4.1
13500 6.8 44.2 240 19 10 9.0 5.0 31.5 88.6 -3.7 751 3.8
13000 8.1 46.6 235 17 9 9.4 5.2 31.4 88.5 -3.8 695 3.5
12500 9.5 49.1 230 15 8 9.3 5.1 31.3 88.4 -3.8 638 3.2
12000 11.0 51.8 225 14 7 10.0 5.5 31.3 88.3 -3.9 580 2.9
11500 12.5 54.5 225 14 7 10.1 5.6 31.3 88.4 -3.9 520 2.6
11000 13.9 57.0 230 14 7 8.9 4.9 31.3 88.4 -3.9 462 2.3
10500 15.2 59.4 230 13 7 8.9 4.9 31.2 88.1 -4.1 409 2.1
10250 15.9 60.6 230 13 7 10.5 5.8 31.1 88.1 -4.1 380 1.9
10000 16.7 62.1 230 13 7 9.5 5.2 31.2 88.2 -4.0 349 1.8
9750 17.3 63.1 230 13 6 8.0 4.4 31.1 88.0 -4.2 323 1.6
9500 18.0 64.4 230 12 6 8.5 4.7 31.0 87.8 -4.3 297 1.5
9250 18.6 65.5 235 12 6 8.1 4.4 30.9 87.6 -4.4 271 1.4
9000 19.1 66.4 235 11 6 6.6 3.6 30.7 87.3 -4.6 247 1.3
8750 19.6 67.3 235 11 6 5.7 3.1 30.4 86.7 -4.9 227 1.2
8500 20.0 68.0 235 10 5 6.1 3.3 30.1 86.2 -5.2 207 1.1
8250 20.4 68.7 235 10 5 5.6 3.1 29.8 85.7 -5.5 186 0.9
8000 20.7 69.3 235 9 5 3.5 1.9 29.4 85.0 -6.0 170 0.9
7750 20.8 69.4 230 8 4 2.2 1.2 28.9 84.0 -6.6 159 0.8
7500 20.9 69.6 230 7 3 3.0 1.6 28.3 83.0 -7.3 148 0.8
7250 21.1 70.0 230 6 3 1.5 0.8 27.8 82.0 -7.9 137 0.7
7000 21.0 69.8 230 4 2 -0.8 -0.5 27.0 80.7 -8.7 133 0.7
6750 20.8 69.4 235 2 1 -1.7 -0.9 26.2 79.2 -9.6 130 0.7
6500 20.7 69.3 295 1 0 -0.6 -0.3 25.3 77.6 -10.5 128 0.6
6250 20.5 68.9 015 2 1 -6.0 -3.3 24.5 76.0 -11.5 126 0.6
6000 19.7 67.5 005 2 1 -10.5 -5.8 23.0 73.4 -13.0 142 0.7
5750 18.9 66.0 360 3 1 -13.1 -7.2 21.5 70.6 -14.6 159 0.8
5500 17.3 63.1 360 2 1 -23.0 -12.6 19.4 66.9 -16.9 198 1.0
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/17/2024 at 0900 MDT | 06/17/2024 at 1200 MDT
|
CAPE... +956.7 LI... -4.4 | CAPE... +1629.6 LI... -4.3
CINH... -305.4 K Index... +7.0 | CINH... -179.0 K Index... -10.0
|
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 -60.5 -76.9 245 42 22 2.0 1.1 | -60.7 -77.3 240 40 21 1.5 0.8
45000 -57.3 -71.1 250 48 25 2.4 1.3 | -58.1 -72.6 245 52 27 2.6 1.4
40000 -53.3 -63.9 255 36 19 6.1 3.4 | -53.7 -64.7 250 46 24 7.0 3.8
38000 -49.6 -57.3 255 36 18 6.2 3.4 | -49.8 -57.6 250 44 23 6.6 3.6
36000 -45.9 -50.6 250 36 18 6.2 3.4 | -45.8 -50.4 245 43 22 6.6 3.6
34000 -42.0 -43.6 250 35 18 6.9 3.8 | -41.4 -42.5 245 43 22 7.7 4.2
32000 -37.8 -36.0 245 35 18 6.9 3.8 | -36.8 -34.2 240 43 22 7.7 4.2
30000 -33.6 -28.5 245 33 17 7.4 4.0 | -32.6 -26.7 235 40 21 6.6 3.6
29000 -30.8 -23.4 240 31 16 7.4 4.0 | -30.1 -22.2 230 38 19 6.7 3.6
28000 -28.6 -19.5 235 30 15 7.4 4.0 | -28.1 -18.6 230 35 18 6.7 3.7
27000 -26.3 -15.3 235 29 15 7.9 4.3 | -25.9 -14.6 225 35 18 7.8 4.3
26000 -24.0 -11.2 235 28 14 7.9 4.3 | -23.6 -10.5 225 34 18 7.8 4.3
25000 -21.6 -6.9 230 26 14 7.9 4.3 | -21.3 -6.3 220 34 17 7.8 4.3
24000 -19.4 -2.9 225 26 13 7.4 4.0 | -18.9 -2.0 220 33 17 8.0 4.4
23000 -17.2 1.0 225 26 13 7.3 4.0 | -16.5 2.3 215 32 17 8.0 4.4
22000 -15.0 5.0 220 26 14 7.3 4.0 | -14.1 6.6 215 32 16 8.1 4.4
21000 -12.7 9.1 220 28 14 7.9 4.3 | -11.8 10.8 215 31 16 7.5 4.1
20000 -10.3 13.5 225 29 15 7.9 4.3 | -9.5 14.9 220 32 16 7.5 4.1
19500 -9.1 15.6 230 30 16 7.9 4.3 | -8.4 16.9 225 32 16 7.5 4.1
19000 -8.0 17.6 230 31 16 8.2 4.5 | -7.3 18.9 225 32 17 7.7 4.2
18500 -6.6 20.1 230 33 17 9.0 4.9 | -6.0 21.2 225 33 17 8.6 4.7
18000 -5.3 22.5 230 34 17 9.0 4.9 | -4.8 23.4 225 33 17 8.6 4.7
17500 -4.0 24.8 230 34 18 8.5 4.7 | -3.5 25.7 225 34 17 8.3 4.6
17000 -2.8 27.0 230 35 18 8.4 4.6 | -2.2 28.0 225 35 18 8.2 4.5
16500 -1.5 29.3 230 35 18 8.2 4.5 | -1.0 30.2 220 36 18 8.2 4.5
16000 -0.4 31.3 230 35 18 7.5 4.1 | 0.2 32.4 220 37 19 8.1 4.4
15500 0.7 33.3 225 35 18 7.5 4.1 | 2.0 35.6 220 38 20 8.1 4.5
15000 2.5 36.5 225 33 17 8.9 4.9 | 3.2 37.8 215 39 20 8.2 4.5
14500 3.8 38.8 220 32 16 9.0 4.9 | 4.4 39.9 215 39 20 8.2 4.5
14000 5.2 41.4 220 30 16 9.1 5.0 | 5.6 42.1 215 39 20 8.3 4.5
13500 6.5 43.7 215 29 15 9.2 5.0 | 6.8 44.2 215 39 20 8.4 4.6
13000 7.9 46.2 210 28 14 9.1 5.0 | 8.0 46.4 215 38 20 8.2 4.5
12500 9.3 48.7 210 27 14 9.1 5.0 | 9.2 48.6 210 37 19 8.3 4.6
12000 10.6 51.1 210 26 14 8.2 4.5 | 10.3 50.5 210 35 18 8.6 4.7
11500 11.8 53.2 210 25 13 8.1 4.4 | 11.6 52.9 210 33 17 8.7 4.8
11000 13.0 55.4 210 24 12 8.3 4.5 | 12.9 55.2 215 31 16 8.8 4.8
10500 14.2 57.6 210 23 12 8.3 4.6 | 14.2 57.6 210 30 16 8.9 4.9
10250 14.9 58.8 210 22 11 9.5 5.2 | 14.9 58.8 210 30 15 10.2 5.6
10000 15.6 60.1 210 20 11 8.9 4.9 | 15.7 60.3 210 29 15 9.5 5.2
9750 16.2 61.2 210 19 10 7.7 4.2 | 16.3 61.3 210 28 15 8.0 4.4
9500 16.7 62.1 210 18 9 7.7 4.2 | 16.9 62.4 210 28 14 8.9 4.9
9250 17.3 63.1 215 16 8 8.9 4.9 | 17.5 63.5 210 27 14 6.9 3.8
9000 17.9 64.2 215 15 8 3.5 1.9 | 18.0 64.4 210 26 14 6.1 3.4
8750 17.8 64.0 215 13 7 -1.9 -1.0 | 18.5 65.3 210 25 13 7.5 4.1
8500 17.7 63.9 220 11 6 0.5 0.2 | 19.0 66.2 205 23 12 7.0 3.9
8250 17.5 63.5 225 9 5 -2.9 -1.6 | 19.5 67.1 205 22 11 7.5 4.1
8000 16.8 62.2 230 6 3 -8.9 -4.9 | 19.7 67.5 205 19 10 -4.6 -2.5
7750 15.8 60.4 250 3 2 -8.2 -4.5 | 18.6 65.5 195 14 7 -13.1 -7.2
7500 15.0 59.0 305 2 1 -7.8 -4.3 | 17.5 63.5 185 10 5 -10.2 -5.6
7250 14.1 57.4 355 4 2 -2.0 -1.1 | 16.4 61.5 165 7 4 -7.9 -4.3
7000 14.2 57.6 015 6 3 7.4 4.1 | 15.7 60.3 140 6 3 0.4 0.2
6750 14.7 58.5 025 8 4 7.1 3.9 | 15.9 60.6 130 5 3 6.5 3.6
6500 15.1 59.2 025 9 5 6.0 3.3 | 16.3 61.3 115 5 3 6.6 3.6
6250 15.5 59.9 025 10 5 5.7 3.1 | 16.8 62.2 105 5 2 8.7 4.8
6000 16.0 60.8 020 9 5 5.3 2.9 | 17.6 63.7 100 5 2 11.9 6.5
5750 16.4 61.5 020 9 4 5.0 2.7 | 18.5 65.3 095 5 2 11.3 6.2
5500 16.9 62.4 010 7 4 8.4 4.6 | 19.4 66.9 090 4 2 18.7 10.3
06/17/2024 at 1500 MDT | 06/17/2024 at 1800 MDT
|
CAPE... +1370.1 LI... -3.5 | CAPE... +182.2 LI... -0.5
CINH... -12.0 K Index... +8.7 | CINH... -8.7 K Index... +13.2
|
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 -61.5 -78.7 235 43 22 1.4 0.8 | -62.3 -80.1 230 42 21 1.9 1.0
45000 -58.7 -73.7 250 49 25 3.6 2.0 | -58.9 -74.0 245 43 22 3.7 2.0
40000 -52.8 -63.0 255 50 26 6.9 3.8 | -52.8 -63.0 250 47 24 7.0 3.9
38000 -48.9 -56.0 250 50 26 6.5 3.6 | -48.8 -55.8 250 47 24 6.7 3.7
36000 -45.0 -49.0 250 50 26 6.5 3.6 | -44.8 -48.6 250 47 24 6.7 3.7
34000 -40.8 -41.4 245 50 26 7.4 4.1 | -40.3 -40.5 250 46 24 7.8 4.3
32000 -36.3 -33.3 245 50 26 7.4 4.1 | -35.6 -32.1 250 46 24 7.8 4.3
30000 -32.0 -25.6 240 48 25 7.2 3.9 | -31.4 -24.5 245 46 24 6.6 3.6
29000 -29.3 -20.7 240 46 24 7.2 3.9 | -29.0 -20.2 245 45 23 6.7 3.7
28000 -27.2 -17.0 235 45 23 7.2 3.9 | -27.0 -16.6 240 45 23 6.7 3.7
27000 -25.1 -13.2 235 44 22 6.7 3.7 | -24.8 -12.6 240 44 23 7.6 4.2
26000 -23.1 -9.6 230 43 22 6.7 3.7 | -22.5 -8.5 235 42 22 7.6 4.2
25000 -21.1 -6.0 225 42 22 6.7 3.7 | -20.2 -4.4 230 41 21 7.6 4.2
24000 -18.8 -1.8 225 41 21 8.8 4.8 | -18.1 -0.6 230 40 20 7.1 3.9
23000 -16.2 2.8 225 40 21 8.9 4.9 | -16.0 3.2 225 38 20 7.1 3.9
22000 -13.5 7.7 225 39 20 8.9 4.9 | -13.9 7.0 225 37 19 7.1 3.9
21000 -11.1 12.0 225 38 19 7.4 4.1 | -11.7 10.9 225 34 18 7.8 4.3
20000 -9.0 15.8 225 36 18 7.4 4.1 | -9.4 15.1 230 31 16 7.9 4.3
19500 -7.9 17.8 225 35 18 7.4 4.1 | -8.3 17.1 230 30 15 7.9 4.3
19000 -6.8 19.8 225 34 17 7.4 4.1 | -7.2 19.0 235 28 15 8.0 4.4
18500 -5.7 21.7 225 33 17 7.3 4.0 | -5.9 21.4 230 27 14 8.6 4.7
18000 -4.5 23.9 225 32 16 7.3 4.0 | -4.7 23.5 225 27 14 8.5 4.7
17500 -3.4 25.9 225 31 16 8.2 4.5 | -3.4 25.9 220 26 14 8.9 4.9
17000 -2.1 28.2 220 30 16 8.5 4.6 | -2.1 28.2 220 26 14 9.1 5.0
16500 -0.9 30.4 215 29 15 8.4 4.6 | -0.7 30.7 215 26 14 9.1 5.0
16000 0.3 32.5 215 29 15 8.0 4.4 | 0.7 33.3 215 27 14 9.5 5.2
15500 2.1 35.8 210 29 15 8.3 4.6 | 2.1 35.8 210 27 14 9.4 5.2
15000 3.4 38.1 205 28 15 8.9 4.9 | 4.2 39.6 210 26 14 9.4 5.2
14500 4.7 40.5 205 28 15 8.9 4.9 | 5.6 42.1 205 26 13 9.4 5.1
14000 6.0 42.8 200 28 15 9.3 5.1 | 7.1 44.8 205 26 13 9.8 5.4
13500 7.4 45.3 200 28 14 9.2 5.1 | 8.5 47.3 205 25 13 9.8 5.4
13000 8.8 47.8 200 28 14 9.8 5.4 | 10.0 50.0 200 25 13 9.3 5.1
12500 10.2 50.4 200 27 14 9.8 5.4 | 11.3 52.3 200 24 12 9.2 5.0
12000 11.7 53.1 195 27 14 9.6 5.3 | 12.7 54.9 200 23 12 9.5 5.2
11500 13.1 55.6 195 26 13 9.5 5.2 | 14.2 57.6 200 23 12 9.8 5.4
11000 14.5 58.1 195 25 13 9.7 5.3 | 15.6 60.1 200 22 11 9.9 5.4
10500 15.9 60.6 190 23 12 9.6 5.2 | 17.1 62.8 200 21 11 9.6 5.3
10250 16.6 61.9 190 23 12 8.7 4.8 | 17.8 64.0 200 20 10 8.8 4.8
10000 17.2 63.0 190 22 11 8.9 4.9 | 18.5 65.3 200 20 10 9.7 5.3
9750 17.8 64.0 185 21 11 9.0 4.9 | 19.2 66.6 200 19 10 10.5 5.7
9500 18.4 65.1 185 19 10 9.5 5.2 | 20.0 68.0 200 17 9 11.4 6.2
9250 19.0 66.2 180 18 9 8.0 4.4 | 20.7 69.3 200 16 8 8.0 4.4
9000 19.5 67.1 180 17 9 7.7 4.2 | 21.2 70.2 200 15 8 7.0 3.9
8750 20.0 68.0 175 15 8 9.1 5.0 | 21.9 71.4 200 14 7 10.6 5.8
8500 20.6 69.1 170 13 7 9.7 5.3 | 22.6 72.7 200 12 6 11.1 6.1
8250 21.2 70.2 160 12 6 7.5 4.1 | 23.4 74.1 200 10 5 9.6 5.3
8000 21.6 70.9 155 11 6 6.9 3.8 | 24.0 75.2 205 9 5 7.6 4.2
7750 22.1 71.8 145 10 5 9.2 5.0 | 24.6 76.3 205 8 4 9.1 5.0
7500 22.8 73.0 135 9 4 8.8 4.8 | 25.3 77.5 205 7 4 10.0 5.5
7250 23.4 74.1 125 8 4 9.1 5.0 | 26.1 79.0 210 6 3 10.0 5.5
7000 24.1 75.4 115 8 4 10.7 5.9 | 26.8 80.2 215 6 3 9.1 5.0
6750 24.9 76.8 110 8 4 10.4 5.7 | 27.5 81.5 215 5 3 9.1 5.0
6500 25.6 78.1 110 8 4 9.1 5.0 | 28.2 82.8 220 5 3 10.3 5.6
6250 26.3 79.3 105 8 4 10.0 5.5 | 28.9 84.0 220 4 2 9.9 5.5
6000 27.1 80.8 105 7 4 11.9 6.5 | 29.6 85.3 225 4 2 9.7 5.3
5750 28.2 82.8 100 7 4 18.3 10.0 | 30.5 86.9 230 4 2 13.1 7.2
5500 29.8 85.6 100 7 4 26.1 14.3 | 31.7 89.1 235 3 1 19.4 10.6
________________________________________________________________________________
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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