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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 191416
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0816 MDT Tuesday, June 19, 2018
This forecast is for Tuesday, June 19, 2018:
If the trigger temperature of 69.6 F/20.9 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 10565 ft MSL (5280 ft AGL)
Forecast maximum temperature................... 73.0 F/23.2 C
Time of trigger temperature.................... 1500 MDT
Time of overdevelopment........................ 1600 MDT
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................. 8496 ft MSL (3211 ft AGL)
Thermal soaring outlook for Wednesday 06/20.... Good
Wave Soaring Index............................. Good
Wave Soaring Index trend (to 1800 MDT)......... Becoming poor
Height of stable layer (12-18K ft MSL)......... 15111 ft MSL (9826 ft AGL)
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 19778 ft MSL (14493 ft AGL)
Wave soaring outlook for Wednesday 06/20....... Fair
Remarks... Scattered afternoon thunderstorms
***ATTENTION Soaring Forecast Users***The National Weather Service in Boulder wants to hear from you.
Please send and email to paul.t.schlatter@noaa.gov and let us know how you use the Soaring Forecast. Thanks!
Sunrise/Sunset.................... 05:31:16 / 20:30:32 MDT
Total possible sunshine........... 14 hr 59 min 16 sec (899 min 16 sec)
Altitude of sun at 13:00:54 MDT... 73.66 degrees
Upper air data from rawinsonde observation taken on 06/19/2018 at 0600 MDT
Freezing level.................. 14291 ft MSL (9006 ft AGL)
Convective condensation level... 10945 ft MSL (5660 ft AGL)
Lifted condensation level....... 10741 ft MSL (5456 ft AGL)
Lifted index.................... -2.9
K index......................... +22.6
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 -59.5 -75.1 240 47 24 4.1 2.2 94.3 201.8 41.6 M M
45000 -53.8 -64.8 245 53 27 1.8 1.0 79.5 175.1 35.3 M M
40000 -53.7 -64.7 240 57 29 -3.4 -1.9 55.9 132.7 22.1 M M
38000 -52.0 -61.6 220 53 27 5.5 3.0 49.8 121.6 18.5 M M
36000 -48.2 -54.8 220 49 25 8.5 4.7 46.8 116.3 16.9 M M
34000 -43.2 -45.8 220 49 25 8.8 4.9 45.5 113.9 16.4 M M
32000 -37.9 -36.2 230 51 26 8.9 4.9 44.7 112.5 16.3 M M
30000 -33.0 -27.4 230 54 28 7.5 4.1 43.7 110.7 15.9 M M
29000 -30.7 -23.3 230 54 28 7.5 4.1 42.8 109.0 15.3 M M
28000 -27.9 -18.2 235 55 28 8.0 4.4 41.8 107.2 14.8 M M
27000 -25.4 -13.7 235 55 28 8.4 4.6 41.3 106.3 14.6 M M
26000 -22.8 -9.0 240 51 26 8.4 4.6 40.8 105.4 14.3 M M
25000 -21.0 -5.8 240 47 24 4.3 2.4 39.4 103.0 13.4 M M
24000 -19.5 -3.1 245 47 24 5.4 3.0 37.7 99.9 12.2 M M
23000 -17.9 -0.2 240 40 21 5.3 2.9 36.1 97.0 10.9 M M
22000 -15.7 3.7 235 33 17 9.0 4.9 35.3 95.5 10.4 M M
21000 -12.9 8.8 230 27 14 9.1 5.0 35.1 95.2 10.4 M M
20000 -10.1 13.8 230 30 15 9.2 5.0 34.9 94.7 10.3 M M
19500 -8.8 16.2 230 31 16 9.3 5.1 34.7 94.5 10.3 M M
19000 -7.4 18.7 230 31 16 8.7 4.8 34.6 94.3 10.2 M M
18500 -6.1 21.0 230 30 15 8.4 4.6 34.3 93.8 10.0 M M
18000 -4.9 23.2 225 29 15 8.4 4.6 34.1 93.3 9.9 M M
17500 -3.6 25.5 225 28 15 8.4 4.6 33.8 92.9 9.7 M M
17000 -2.4 27.7 220 27 14 8.5 4.7 33.6 92.5 9.6 M M
16500 -1.1 30.0 220 27 14 9.2 5.0 33.5 92.2 9.5 M M
16000 -0.3 31.5 215 26 13 0.6 0.4 32.8 91.0 8.9 M M
15500 -0.3 31.5 220 23 12 0.5 0.3 31.3 88.3 7.5 M M
15000 -0.3 31.5 230 20 11 -6.6 -3.6 30.0 85.9 6.0 M M
14500 -0.8 30.6 240 18 9 11.4 6.3 28.1 82.7 4.1 M M
14000 1.0 33.8 255 16 8 8.4 4.6 27.8 82.1 3.8 M M
13500 2.2 36.0 265 16 8 8.4 4.6 27.6 81.7 3.5 M M
13000 3.4 38.1 270 15 8 8.1 4.5 27.4 81.3 3.3 M M
12500 4.3 39.7 270 12 6 5.1 2.8 26.8 80.3 2.7 M M
12000 5.0 41.0 265 10 5 5.4 2.9 26.1 79.1 2.0 M M
11500 5.7 42.3 265 9 5 5.4 3.0 25.4 77.8 1.3 M M
11000 6.5 43.7 265 8 4 5.4 3.0 24.8 76.6 0.6 M M
10500 7.2 45.0 280 5 2 5.5 3.0 24.1 75.3 -0.2 368 1.9
10250 7.5 45.5 290 4 2 5.6 3.1 23.7 74.7 -0.5 350 1.8
10000 7.9 46.2 290 5 2 5.7 3.1 23.4 74.2 -0.9 331 1.7
9750 8.3 46.9 280 4 2 5.7 3.1 23.1 73.6 -1.2 311 1.6
9500 8.7 47.7 270 3 2 5.7 3.1 22.8 73.0 -1.6 292 1.5
9250 9.1 48.4 250 2 1 5.7 3.1 22.5 72.5 -1.9 273 1.4
9000 9.5 49.1 215 2 1 4.8 2.6 22.1 71.9 -2.2 254 1.3
8750 9.8 49.6 170 3 2 4.2 2.3 21.7 71.1 -2.6 237 1.2
8500 10.2 50.4 155 5 3 4.4 2.4 21.3 70.3 -3.0 220 1.1
8250 10.5 50.9 150 8 4 4.4 2.4 20.9 69.6 -3.4 202 1.0
8000 10.8 51.4 145 10 5 4.4 2.4 20.5 68.9 -3.8 185 0.9
7750 11.2 52.2 135 12 6 4.4 2.4 20.1 68.1 -4.2 167 0.8
7500 11.5 52.7 130 14 7 4.3 2.4 19.7 67.4 -4.6 150 0.8
7250 11.8 53.2 125 16 8 4.7 2.6 19.3 66.7 -5.0 132 0.7
7000 12.2 54.0 120 18 9 3.2 1.7 18.9 65.9 -5.4 115 0.6
6750 12.2 54.0 115 18 9 -5.1 -2.8 18.1 64.6 -6.2 108 0.6
6500 11.8 53.2 115 19 10 2.9 1.6 17.0 62.6 -7.3 112 0.6
6250 12.5 54.5 110 19 10 13.3 7.3 17.1 62.8 -7.3 82 0.4
6000 13.3 55.9 110 20 10 10.5 5.8 17.2 63.0 -7.2 52 0.3
5750 14.1 57.4 110 16 8 11.5 6.3 17.3 63.2 -7.2 21 0.1
5500 14.8 58.6 105 11 6 10.6 5.8 17.4 63.4 -7.2 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/19/2018 at 0900 MDT | 06/19/2018 at 1200 MDT
|
CAPE... +668.0 LI... -3.2 | CAPE... +1611.5 LI... -5.7
CINH... -87.9 K Index... +22.2 | CINH... -28.0 K Index... +26.8
|
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 -58.8 -73.8 240 21 11 3.7 2.0 | -58.2 -72.8 245 18 9 4.1 2.3
45000 -54.1 -65.4 250 32 16 1.4 0.8 | -52.8 -63.0 255 27 14 2.1 1.2
40000 -51.9 -61.4 245 31 16 2.6 1.4 | -49.5 -57.1 245 32 16 1.6 0.9
38000 -50.2 -58.4 240 29 15 2.9 1.6 | -48.7 -55.7 240 31 16 1.3 0.7
36000 -48.2 -54.8 230 28 14 3.0 1.6 | -47.8 -54.0 230 30 15 1.5 0.8
34000 -43.8 -46.8 225 27 14 8.7 4.8 | -44.5 -48.1 225 30 15 7.2 4.0
32000 -38.6 -37.5 225 28 14 8.7 4.8 | -40.1 -40.2 225 31 16 7.2 4.0
30000 -33.7 -28.7 225 28 14 8.0 4.4 | -35.3 -31.5 225 30 16 8.3 4.6
29000 -31.3 -24.3 225 28 14 8.0 4.4 | -32.8 -27.0 225 30 15 8.4 4.6
28000 -28.9 -20.0 230 28 14 8.0 4.4 | -30.3 -22.5 225 30 15 8.4 4.6
27000 -26.6 -15.9 230 27 14 7.2 4.0 | -28.0 -18.4 225 29 15 7.8 4.3
26000 -24.5 -12.1 230 26 13 7.3 4.0 | -25.6 -14.1 230 28 14 7.8 4.3
25000 -22.3 -8.1 230 25 13 7.3 4.0 | -23.3 -9.9 230 27 14 7.8 4.3
24000 -20.2 -4.4 230 23 12 7.2 3.9 | -21.1 -6.0 230 26 14 7.0 3.8
23000 -18.0 -0.4 230 22 11 7.2 4.0 | -19.0 -2.2 230 25 13 7.0 3.8
22000 -15.9 3.4 230 21 11 7.2 3.9 | -16.9 1.6 235 24 12 7.0 3.9
21000 -13.7 7.3 230 20 10 7.4 4.1 | -14.9 5.2 235 22 11 6.9 3.8
20000 -11.5 11.3 230 19 10 7.4 4.1 | -12.8 9.0 235 20 11 7.0 3.8
19500 -10.4 13.3 230 19 10 7.4 4.1 | -11.3 11.7 240 19 10 6.9 3.8
19000 -8.8 16.2 230 18 9 7.2 3.9 | -10.3 13.5 240 18 9 7.5 4.1
18500 -7.7 18.1 230 18 9 7.3 4.0 | -9.2 15.4 240 17 9 7.6 4.2
18000 -6.7 19.9 230 17 9 7.4 4.1 | -8.1 17.4 235 16 8 7.9 4.3
17500 -5.6 21.9 235 17 9 7.5 4.1 | -6.9 19.6 235 16 8 8.3 4.5
17000 -4.5 23.9 235 17 9 7.6 4.2 | -5.7 21.7 235 15 8 8.3 4.5
16500 -3.4 25.9 230 16 8 7.9 4.4 | -4.4 24.1 230 14 7 8.8 4.8
16000 -2.2 28.0 230 15 8 7.9 4.3 | -3.2 26.2 230 14 7 8.8 4.8
15500 -1.0 30.2 230 15 8 8.2 4.5 | -1.9 28.6 230 13 7 8.9 4.9
15000 0.2 32.4 230 14 7 8.2 4.5 | -0.6 30.9 225 13 7 8.9 4.9
14500 1.4 34.5 225 13 7 8.2 4.5 | 0.8 33.4 225 12 6 8.9 4.9
14000 2.6 36.7 225 12 6 8.1 4.4 | 2.1 35.8 225 12 6 9.0 4.9
13500 3.8 38.8 225 11 6 8.0 4.4 | 3.4 38.1 225 11 6 8.9 4.9
13000 4.9 40.8 220 10 5 7.2 4.0 | 4.7 40.5 220 11 6 8.6 4.7
12500 5.9 42.6 220 8 4 7.3 4.0 | 6.0 42.8 220 10 5 8.7 4.8
12000 6.9 44.4 215 7 4 6.2 3.4 | 7.1 44.8 220 10 5 7.3 4.0
11500 7.7 45.9 215 6 3 6.5 3.6 | 8.1 46.6 215 9 5 7.6 4.2
11000 8.5 47.3 210 5 3 4.8 2.6 | 9.0 48.2 210 8 4 5.3 2.9
10500 9.1 48.4 210 4 2 5.2 2.8 | 9.7 49.5 205 7 4 5.7 3.1
10250 9.4 48.9 205 4 2 4.5 2.4 | 10.1 50.2 205 7 3 6.0 3.3
10000 9.6 49.3 200 3 2 3.0 1.6 | 10.5 50.9 200 6 3 4.5 2.5
9750 9.8 49.6 200 3 1 2.7 1.5 | 10.7 51.3 195 5 3 3.4 1.9
9500 9.9 49.8 195 2 1 2.8 1.6 | 10.9 51.6 190 5 2 3.8 2.1
9250 10.0 50.0 190 2 1 2.6 1.4 | 11.1 52.0 185 4 2 2.7 1.5
9000 10.1 50.2 190 2 1 2.2 1.2 | 11.2 52.2 180 4 2 3.3 1.8
8750 10.2 50.4 175 2 1 2.0 1.1 | 11.4 52.5 170 3 2 4.7 2.6
8500 10.3 50.5 165 2 1 2.5 1.4 | 11.7 53.1 150 3 1 4.6 2.5
8250 10.4 50.7 155 2 1 4.1 2.3 | 12.0 53.6 135 3 2 5.5 3.0
8000 10.8 51.4 150 3 1 4.7 2.6 | 12.4 54.3 120 3 2 6.6 3.6
7750 11.0 51.8 145 3 2 4.0 2.2 | 12.8 55.0 115 4 2 7.2 3.9
7500 11.3 52.3 140 4 2 4.3 2.4 | 13.4 56.1 110 4 2 8.1 4.5
7250 11.7 53.1 140 3 2 5.0 2.7 | 14.0 57.2 105 4 2 9.4 5.1
7000 12.0 53.6 140 3 2 5.1 2.8 | 14.7 58.5 100 4 2 9.5 5.2
6750 12.4 54.3 140 3 1 7.2 4.0 | 15.4 59.7 095 5 2 8.6 4.7
6500 13.1 55.6 140 3 1 9.5 5.2 | 16.0 60.8 095 4 2 9.0 5.0
6250 13.8 56.8 140 3 1 9.9 5.4 | 16.7 62.1 090 4 2 10.4 5.7
6000 14.5 58.1 140 3 1 9.1 5.0 | 17.4 63.3 090 4 2 8.9 4.9
5750 15.2 59.4 135 3 1 12.0 6.6 | 18.2 64.8 085 4 2 13.4 7.3
5500 16.4 61.5 135 2 1 19.4 10.6 | 19.6 67.3 085 4 2 26.5 14.5
06/19/2018 at 1500 MDT | 06/19/2018 at 1800 MDT
|
CAPE... +2010.9 LI... -6.4 | CAPE... +2130.7 LI... -6.6
CINH... -13.7 K Index... +32.5 | CINH... -11.7 K Index... +33.2
|
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 -57.9 -72.2 250 17 9 3.8 2.1 | -58.1 -72.6 260 17 9 3.5 1.9
45000 -52.7 -62.9 260 23 12 2.3 1.3 | -53.2 -63.8 270 20 11 2.5 1.3
40000 -49.3 -56.7 260 26 14 1.9 1.0 | -49.6 -57.3 275 22 12 2.1 1.2
38000 -48.3 -54.9 260 25 13 1.6 0.9 | -48.4 -55.1 280 22 11 2.0 1.1
36000 -47.2 -53.0 260 23 12 1.8 1.0 | -47.0 -52.6 280 21 11 2.1 1.2
34000 -44.2 -47.6 260 23 12 6.1 3.4 | -43.9 -47.0 275 20 11 6.3 3.5
32000 -40.6 -41.1 260 24 12 6.1 3.4 | -40.1 -40.2 270 21 11 6.4 3.5
30000 -36.1 -33.0 260 24 12 8.0 4.4 | -35.7 -32.3 265 21 11 7.9 4.3
29000 -33.7 -28.7 255 24 12 8.0 4.4 | -33.3 -27.9 265 21 11 7.9 4.3
28000 -31.3 -24.3 255 24 13 8.0 4.4 | -31.0 -23.8 260 21 11 7.9 4.3
27000 -29.0 -20.2 250 24 12 7.9 4.3 | -28.7 -19.7 255 21 11 7.7 4.2
26000 -26.6 -15.9 250 24 12 7.9 4.3 | -26.4 -15.5 250 21 11 7.7 4.2
25000 -24.2 -11.6 250 23 12 7.9 4.3 | -24.0 -11.2 250 21 11 7.7 4.2
24000 -21.9 -7.4 245 22 12 7.8 4.3 | -21.8 -7.2 245 20 10 7.7 4.2
23000 -19.6 -3.3 245 22 11 7.8 4.3 | -19.5 -3.1 245 19 10 7.8 4.3
22000 -17.3 0.9 240 21 11 7.8 4.3 | -17.2 1.0 240 18 9 7.8 4.3
21000 -15.0 5.0 240 20 10 7.8 4.3 | -14.8 5.4 240 17 9 8.5 4.7
20000 -12.7 9.1 240 18 9 7.9 4.3 | -12.3 9.9 240 16 8 8.6 4.7
19500 -11.6 11.1 240 18 9 7.9 4.4 | -10.4 13.3 240 15 8 8.7 4.8
19000 -9.8 14.4 235 17 9 8.2 4.5 | -9.2 15.4 240 15 7 8.0 4.4
18500 -8.7 16.3 235 17 9 8.2 4.5 | -8.0 17.6 240 14 7 8.1 4.4
18000 -7.5 18.5 235 16 8 8.3 4.6 | -6.9 19.6 245 13 7 8.2 4.5
17500 -6.2 20.8 235 15 8 8.5 4.6 | -5.6 21.9 245 13 7 8.3 4.6
17000 -5.0 23.0 235 15 8 8.4 4.6 | -4.4 24.1 250 12 6 8.3 4.6
16500 -3.7 25.3 235 14 7 9.1 5.0 | -3.2 26.2 250 12 6 8.7 4.8
16000 -2.3 27.9 235 13 7 9.1 5.0 | -1.9 28.6 255 11 6 8.7 4.8
15500 -1.0 30.2 235 13 7 9.2 5.0 | -0.6 30.9 260 11 5 8.7 4.8
15000 0.4 32.7 235 12 6 9.2 5.0 | 0.7 33.3 260 10 5 8.7 4.8
14500 1.7 35.1 235 11 6 9.0 4.9 | 1.9 35.4 265 9 5 8.6 4.7
14000 3.0 37.4 235 11 5 8.8 4.8 | 3.2 37.8 265 9 4 8.6 4.7
13500 4.2 39.6 230 10 5 8.7 4.8 | 4.4 39.9 265 8 4 8.5 4.7
13000 5.4 41.7 230 9 4 8.1 4.4 | 5.6 42.1 265 7 4 8.0 4.4
12500 6.6 43.9 225 7 4 8.2 4.5 | 6.7 44.1 270 6 3 8.1 4.4
12000 7.6 45.7 220 6 3 7.1 3.9 | 7.8 46.0 265 5 3 7.9 4.3
11500 8.6 47.5 210 5 3 7.3 4.0 | 8.9 48.0 260 4 2 8.1 4.5
11000 9.5 49.1 200 5 2 6.0 3.3 | 9.9 49.8 255 3 2 7.0 3.8
10500 10.3 50.5 190 4 2 6.1 3.3 | 10.8 51.4 240 2 1 7.3 4.0
10250 10.7 51.3 180 3 2 6.7 3.7 | 11.4 52.5 225 2 1 7.2 4.0
10000 11.2 52.2 165 3 2 6.3 3.4 | 11.9 53.4 220 2 1 7.0 3.8
9750 11.6 52.9 160 3 2 5.4 3.0 | 12.3 54.1 205 1 1 7.0 3.9
9500 11.9 53.4 150 3 2 5.7 3.1 | 12.8 55.0 185 1 1 7.0 3.9
9250 12.3 54.1 140 3 2 4.9 2.7 | 13.3 55.9 165 1 1 7.1 3.9
9000 12.6 54.7 130 4 2 5.9 3.2 | 13.8 56.8 130 1 1 7.0 3.9
8750 13.1 55.6 120 4 2 7.2 4.0 | 14.3 57.7 110 2 1 6.9 3.8
8500 13.6 56.5 115 4 2 7.0 3.8 | 14.8 58.6 100 2 1 6.9 3.8
8250 14.1 57.4 105 4 2 8.6 4.7 | 15.3 59.5 095 3 1 8.7 4.8
8000 14.7 58.5 100 4 2 9.2 5.0 | 16.0 60.8 085 3 2 9.2 5.0
7750 15.4 59.7 100 5 2 8.4 4.6 | 16.5 61.7 085 3 2 7.6 4.2
7500 16.0 60.8 095 5 2 9.0 5.0 | 17.1 62.8 080 4 2 8.5 4.6
7250 16.7 62.1 095 5 3 10.4 5.7 | 17.8 64.0 080 4 2 10.8 5.9
7000 17.5 63.5 090 5 3 10.5 5.8 | 18.6 65.5 075 4 2 11.1 6.1
6750 18.2 64.8 090 5 3 9.1 5.0 | 19.3 66.7 075 4 2 7.8 4.3
6500 18.9 66.0 090 5 3 9.5 5.2 | 19.9 67.8 070 4 2 8.5 4.7
6250 19.6 67.3 090 5 3 11.0 6.0 | 20.7 69.3 070 4 2 11.2 6.1
6000 20.4 68.7 085 5 2 9.9 5.4 | 21.5 70.7 070 4 2 10.7 5.9
5750 21.2 70.2 085 5 2 12.7 7.0 | 22.3 72.1 070 4 2 10.4 5.7
5500 22.5 72.5 085 4 2 23.9 13.1 | 23.1 73.6 065 4 2 14.2 7.8
________________________________________________________________________________
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.
042613
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- Page last modified: Mar 8th, 2018 20:36 UTC