Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
233
UXUS97 KBOU 160118
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1916 MDT Saturday, June 15, 2024
This forecast is for Sunday, June 16, 2024:
If the trigger temperature of 85.6 F/29.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1455 ft/min (7.4 m/s)
Maximum height of thermals.................. 22270 ft MSL (16964 ft AGL)
Forecast maximum temperature................... 97.0 F/36.6 C
Time of trigger temperature.................... 1100 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 18972 ft MSL (13666 ft AGL)
Thermal soaring outlook for Monday 06/17....... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 18347 ft MSL (13041 ft AGL)
Wave soaring outlook for Monday 06/17.......... Poor
Remarks...
Sunrise/Sunset.................... 05:30:56 / 20:29:49 MDT
Total possible sunshine........... 14 hr 58 min 53 sec (898 min 53 sec)
Altitude of sun at 13:00:23 MDT... 73.61 degrees
Upper air data from numerical model forecast valid on 06/16/2024 at 0600 MDT
Freezing level.................. 15776 ft MSL (10470 ft AGL)
Convective condensation level... 17894 ft MSL (12588 ft AGL)
Lifted condensation level....... 19638 ft MSL (14332 ft AGL)
Lifted index.................... -3.0
K index......................... +19.1
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 -62.1 -79.8 255 40 21 0.7 0.4 M M M M M
45000 -59.8 -75.6 265 47 24 3.8 2.1 M M M M M
40000 -53.8 -64.8 280 61 31 6.9 3.8 M M M M M
38000 -49.8 -57.6 280 57 29 6.6 3.6 M M M M M
36000 -45.8 -50.4 280 53 27 6.7 3.7 M M M M M
34000 -41.4 -42.5 275 50 25 7.6 4.1 M M M M M
32000 -36.3 -33.3 270 46 24 7.4 4.1 M M M M M
30000 -31.7 -25.1 270 40 20 7.7 4.2 43.6 110.4 5.6 M M
29000 -29.4 -20.9 265 37 19 7.7 4.2 42.8 109.1 5.1 M M
28000 -27.1 -16.8 265 33 17 7.7 4.2 42.2 107.9 4.7 M M
27000 -24.8 -12.6 260 31 16 7.5 4.1 41.2 106.2 4.0 M M
26000 -22.6 -8.7 255 30 15 7.6 4.1 40.4 104.7 3.4 M M
25000 -20.3 -4.5 255 28 14 7.7 4.2 39.7 103.4 2.8 M M
24000 -18.3 -0.9 255 27 14 6.2 3.4 38.5 101.2 1.9 M M
23000 -16.5 2.3 255 25 13 6.2 3.4 37.1 98.8 0.8 M M
22000 -14.6 5.7 255 24 13 6.3 3.4 36.0 96.7 -0.2 1635 8.3
21000 -12.6 9.3 260 23 12 7.1 3.9 34.9 94.8 -1.2 1546 7.9
20000 -10.6 12.9 265 22 11 7.1 3.9 33.9 93.1 -2.1 1454 7.4
19500 -9.5 14.9 265 22 11 7.1 3.9 33.5 92.3 -2.5 1409 7.2
19000 -8.5 16.7 265 21 11 7.6 4.2 33.1 91.6 -2.9 1363 6.9
18500 -7.4 18.7 270 22 11 7.9 4.3 32.8 91.0 -3.3 1313 6.7
18000 -6.2 20.8 270 22 12 7.9 4.3 32.5 90.4 -3.6 1264 6.4
17500 -5.0 23.0 270 23 12 9.0 4.9 32.2 90.0 -3.8 1212 6.2
17000 -3.6 25.5 270 22 12 8.9 4.9 32.1 89.7 -4.0 1158 5.9
16500 -1.7 28.9 270 22 11 9.2 5.0 31.9 89.4 -4.2 1076 5.5
16000 -0.3 31.5 270 21 11 9.1 5.0 31.8 89.2 -4.4 1020 5.2
15500 1.0 33.8 270 20 10 9.1 5.0 31.7 89.0 -4.5 965 4.9
15000 2.4 36.3 270 18 9 9.1 5.0 31.6 88.8 -4.6 910 4.6
14500 3.7 38.7 265 17 9 9.2 5.1 31.5 88.6 -4.8 856 4.3
14000 5.1 41.2 265 15 8 9.4 5.2 31.4 88.5 -4.9 799 4.1
13500 6.5 43.7 265 13 7 9.3 5.1 31.3 88.4 -5.0 743 3.8
13000 7.8 46.0 260 11 6 8.6 4.7 31.2 88.1 -5.2 690 3.5
12500 9.0 48.2 255 9 5 8.7 4.7 31.0 87.8 -5.4 637 3.2
12000 10.4 50.7 250 8 4 9.4 5.2 30.9 87.6 -5.6 582 3.0
11500 11.7 53.1 240 7 4 9.4 5.2 30.8 87.5 -5.7 527 2.7
11000 13.0 55.4 230 6 3 8.4 4.6 30.7 87.3 -5.9 473 2.4
10500 14.3 57.7 220 6 3 9.4 5.2 30.5 86.9 -6.1 421 2.1
10250 15.0 59.0 215 6 3 10.7 5.9 30.5 87.0 -6.1 390 2.0
10000 15.8 60.4 210 6 3 9.9 5.4 30.6 87.0 -6.1 359 1.8
9750 16.6 61.9 210 6 3 9.6 5.3 30.6 87.0 -6.1 330 1.7
9500 17.3 63.1 210 6 3 9.8 5.4 30.6 87.0 -6.1 301 1.5
9250 18.0 64.4 205 7 3 9.1 5.0 30.6 87.0 -6.1 272 1.4
9000 18.6 65.5 205 7 4 8.3 4.5 30.5 86.9 -6.2 246 1.2
8750 19.3 66.7 205 8 4 8.6 4.7 30.4 86.7 -6.4 220 1.1
8500 19.9 67.8 205 8 4 8.0 4.4 30.3 86.5 -6.5 194 1.0
8250 20.5 68.9 200 9 4 10.0 5.5 30.2 86.3 -6.6 167 0.9
8000 21.3 70.3 200 9 5 8.8 4.8 30.2 86.4 -6.6 138 0.7
7750 21.7 71.1 200 9 5 5.7 3.2 30.0 86.0 -6.9 116 0.6
7500 22.2 72.0 200 9 5 6.3 3.5 29.7 85.5 -7.2 95 0.5
7250 22.6 72.7 200 10 5 6.5 3.6 29.4 85.0 -7.4 74 0.4
7000 23.1 73.6 200 10 5 6.1 3.4 29.2 84.6 -7.7 52 0.3
6750 23.6 74.5 200 9 5 6.5 3.6 28.9 84.0 -8.0 31 0.2
6500 23.9 75.0 195 9 5 1.6 0.9 28.6 83.4 -8.4 12 0.1
6250 23.6 74.5 200 9 5 -9.4 -5.2 27.5 81.5 -9.5 15 0.1
6000 22.7 72.9 200 9 4 -12.2 -6.7 25.9 78.6 -11.1 35 0.2
5750 21.7 71.1 205 8 4 -18.2 -10.0 24.1 75.4 -12.9 59 0.3
5500 19.5 67.1 215 8 4 -39.2 -21.5 21.3 70.3 -15.9 117 0.6
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/16/2024 at 0900 MDT | 06/16/2024 at 1200 MDT
|
CAPE... 0.0 LI... +1.0 | CAPE... +71.6 LI... -0.4
CINH... 0.0 K Index... +15.6 | CINH... -78.9 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 -63.0 -81.4 260 40 21 0.9 0.5 | -63.0 -81.4 260 34 17 -0.4 -0.2
45000 -60.1 -76.2 275 46 23 4.4 2.4 | -61.3 -78.3 265 40 20 5.0 2.8
40000 -53.3 -63.9 285 53 27 6.8 3.7 | -53.5 -64.3 270 48 25 7.0 3.8
38000 -49.3 -56.7 280 53 27 6.6 3.6 | -49.4 -56.9 270 49 25 6.9 3.8
36000 -45.3 -49.5 280 52 27 6.7 3.7 | -45.2 -49.4 270 50 26 6.9 3.8
34000 -40.9 -41.6 275 52 27 7.6 4.2 | -40.7 -41.3 265 49 25 7.8 4.3
32000 -35.7 -32.3 270 51 26 7.6 4.2 | -36.0 -32.8 265 47 24 7.8 4.3
30000 -30.9 -23.6 270 46 24 8.1 4.4 | -30.8 -23.4 260 45 23 7.7 4.2
29000 -28.5 -19.3 265 43 22 8.1 4.4 | -28.5 -19.3 255 44 23 7.7 4.2
28000 -26.1 -15.0 265 40 21 7.7 4.2 | -26.2 -15.2 255 43 22 7.7 4.2
27000 -24.0 -11.2 260 38 19 6.9 3.8 | -24.0 -11.2 250 41 21 7.5 4.1
26000 -22.0 -7.6 255 36 18 6.9 3.8 | -21.7 -7.1 245 39 20 7.6 4.1
25000 -19.9 -3.8 250 34 17 7.0 3.8 | -19.5 -3.1 240 37 19 7.7 4.2
24000 -17.8 -0.0 245 32 17 6.7 3.7 | -17.4 0.7 240 34 18 6.8 3.8
23000 -15.8 3.6 245 31 16 6.7 3.7 | -15.3 4.5 240 32 16 6.9 3.8
22000 -13.8 7.2 245 29 15 6.8 3.7 | -13.2 8.2 245 29 15 6.9 3.8
21000 -12.0 10.4 245 27 14 5.8 3.2 | -11.3 11.7 245 28 15 6.3 3.4
20000 -10.3 13.5 240 26 13 5.9 3.2 | -9.4 15.1 240 29 15 6.3 3.4
19500 -9.5 14.9 240 25 13 6.0 3.3 | -8.5 16.7 240 29 15 6.3 3.5
19000 -8.6 16.5 240 25 13 6.8 3.7 | -7.6 18.3 240 29 15 6.7 3.7
18500 -7.6 18.3 240 24 12 7.4 4.0 | -6.6 20.1 240 29 15 7.0 3.8
18000 -6.5 20.3 245 24 12 7.3 4.0 | -5.5 22.1 240 29 15 6.9 3.8
17500 -5.3 22.5 245 23 12 9.4 5.2 | -4.5 23.9 240 29 15 8.2 4.5
17000 -3.3 26.1 235 21 11 9.2 5.1 | -2.7 27.1 235 29 15 8.1 4.5
16500 -1.9 28.6 230 20 10 9.3 5.1 | -1.5 29.3 235 28 14 9.1 5.0
16000 -0.5 31.1 225 20 10 9.3 5.1 | -0.1 31.8 230 27 14 9.0 5.0
15500 0.9 33.6 220 19 10 9.0 4.9 | 1.2 34.2 230 27 14 9.3 5.1
15000 2.2 36.0 220 19 10 8.9 4.9 | 2.6 36.7 230 26 13 9.4 5.2
14500 3.5 38.3 215 19 10 9.0 5.0 | 4.0 39.2 230 25 13 9.3 5.1
14000 4.9 40.8 210 19 10 9.4 5.1 | 5.4 41.7 225 25 13 9.1 5.0
13500 6.3 43.3 210 19 10 9.4 5.1 | 6.7 44.1 225 24 13 9.1 5.0
13000 7.7 45.9 210 18 9 9.2 5.0 | 8.1 46.6 220 24 13 9.6 5.2
12500 9.1 48.4 210 17 9 9.2 5.0 | 9.5 49.1 220 24 13 9.5 5.2
12000 10.4 50.7 215 16 8 9.4 5.2 | 10.9 51.6 215 24 13 9.3 5.1
11500 11.8 53.2 215 15 8 9.6 5.3 | 12.3 54.1 215 24 13 9.5 5.2
11000 13.1 55.6 215 14 7 7.3 4.0 | 13.6 56.5 215 24 12 8.0 4.4
10500 14.1 57.4 215 13 7 7.8 4.3 | 14.8 58.6 210 23 12 8.9 4.9
10250 14.7 58.5 215 13 7 9.1 5.0 | 15.5 59.9 210 23 12 9.6 5.3
10000 15.3 59.5 210 12 6 7.3 4.0 | 16.1 61.0 210 22 11 7.0 3.8
9750 15.8 60.4 205 11 6 5.6 3.1 | 16.5 61.7 210 20 10 5.4 3.0
9500 16.2 61.2 200 10 5 6.3 3.5 | 16.9 62.4 205 19 10 6.8 3.7
9250 16.6 61.9 195 10 5 5.2 2.8 | 17.3 63.1 205 18 9 2.9 1.6
9000 16.9 62.4 185 9 4 3.1 1.7 | 17.2 63.0 205 15 8 -2.1 -1.2
8750 17.1 62.8 175 8 4 2.6 1.4 | 17.0 62.6 200 12 6 -1.6 -0.9
8500 17.3 63.1 160 8 4 3.1 1.7 | 16.8 62.2 190 9 5 -2.6 -1.4
8250 17.4 63.3 145 8 4 1.7 0.9 | 16.5 61.7 175 6 3 1.5 0.8
8000 17.4 63.3 125 8 4 -0.3 -0.1 | 16.8 62.2 140 4 2 6.9 3.8
7750 17.4 63.3 110 10 5 -0.6 -0.3 | 17.3 63.1 125 4 2 7.0 3.9
7500 17.3 63.1 100 11 6 -0.6 -0.4 | 17.7 63.9 115 4 2 6.6 3.6
7250 17.2 63.0 090 12 6 -0.9 -0.5 | 18.3 64.9 105 4 2 10.2 5.6
7000 17.1 62.8 075 12 6 -0.3 -0.2 | 19.2 66.6 105 4 2 12.5 6.8
6750 17.1 62.8 065 12 6 1.5 0.8 | 20.0 68.0 100 4 2 9.0 4.9
6500 17.3 63.1 050 11 6 5.5 3.0 | 20.6 69.1 100 4 2 8.9 4.9
6250 17.8 64.0 045 11 5 10.6 5.8 | 21.4 70.5 095 4 2 11.5 6.3
6000 18.7 65.7 045 10 5 12.3 6.8 | 22.3 72.1 095 4 2 13.1 7.2
5750 19.6 67.3 040 10 5 10.0 5.5 | 23.2 73.8 090 4 2 9.1 5.0
5500 20.3 68.5 040 10 5 13.3 7.3 | 23.8 74.8 090 3 2 13.3 7.3
06/16/2024 at 1500 MDT | 06/16/2024 at 1800 MDT
|
CAPE... +964.7 LI... -3.6 | CAPE... +264.2 LI... -0.7
CINH... -9.4 K Index... +21.0 | CINH... -10.5 K Index... +22.5
|
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 -62.5 -80.5 250 37 19 -0.1 -0.0 | -61.5 -78.7 255 40 21 1.4 0.8
45000 -60.7 -77.3 250 43 22 4.5 2.5 | -58.5 -73.3 255 47 24 3.3 1.8
40000 -53.6 -64.5 255 44 23 7.2 4.0 | -53.2 -63.8 230 43 22 6.6 3.6
38000 -49.4 -56.9 255 45 23 7.1 3.9 | -49.4 -56.9 230 45 23 6.4 3.5
36000 -45.1 -49.2 255 47 24 7.1 3.9 | -45.5 -49.9 235 48 25 6.4 3.5
34000 -40.6 -41.1 255 47 24 7.5 4.1 | -41.2 -42.2 235 47 24 7.5 4.1
32000 -36.1 -33.0 255 47 24 7.5 4.1 | -36.7 -34.1 235 46 24 7.5 4.1
30000 -30.8 -23.4 250 45 23 8.1 4.4 | -31.4 -24.5 240 44 22 8.0 4.4
29000 -28.4 -19.1 250 44 23 8.1 4.4 | -29.0 -20.2 240 42 22 8.0 4.4
28000 -26.0 -14.8 245 43 22 8.0 4.4 | -26.6 -15.9 245 41 21 7.7 4.2
27000 -23.7 -10.7 245 42 22 7.9 4.3 | -24.4 -11.9 240 40 21 7.1 3.9
26000 -21.3 -6.3 245 41 21 7.9 4.3 | -22.3 -8.1 240 38 20 7.2 3.9
25000 -18.9 -2.0 240 41 21 8.1 4.4 | -20.2 -4.4 240 37 19 7.2 4.0
24000 -17.0 1.4 240 38 20 6.0 3.3 | -18.2 -0.8 240 34 18 6.9 3.8
23000 -15.2 4.6 240 36 18 6.0 3.3 | -16.2 2.8 240 31 16 6.9 3.8
22000 -13.4 7.9 240 33 17 5.9 3.2 | -14.1 6.6 240 28 14 6.9 3.8
21000 -11.5 11.3 240 31 16 7.0 3.8 | -11.9 10.6 230 27 14 8.2 4.5
20000 -9.4 15.1 235 29 15 7.0 3.8 | -9.5 14.9 225 27 14 8.2 4.5
19500 -8.4 16.9 235 29 15 7.0 3.9 | -8.3 17.1 220 28 14 8.3 4.5
19000 -7.4 18.7 230 28 14 7.4 4.1 | -7.1 19.2 220 28 15 8.5 4.6
18500 -6.3 20.7 225 28 14 7.7 4.2 | -5.8 21.6 215 28 15 8.6 4.7
18000 -5.2 22.6 220 28 15 7.6 4.2 | -4.6 23.7 215 29 15 8.6 4.7
17500 -3.9 25.0 220 29 15 9.5 5.2 | -3.3 26.1 210 29 15 9.1 5.0
17000 -2.6 27.3 215 28 15 9.3 5.1 | -1.9 28.6 210 28 15 9.1 5.0
16500 -0.5 31.1 215 28 15 9.3 5.1 | -0.5 31.1 210 28 14 9.3 5.1
16000 0.8 33.4 210 28 15 9.3 5.1 | 0.9 33.6 210 28 14 9.5 5.2
15500 2.2 36.0 210 28 15 9.3 5.1 | 3.0 37.4 205 27 14 9.7 5.3
15000 3.6 38.5 210 28 15 9.4 5.1 | 4.5 40.1 205 27 14 9.8 5.4
14500 5.0 41.0 205 28 14 9.4 5.2 | 5.9 42.6 205 26 14 9.8 5.3
14000 6.4 43.5 205 28 14 9.5 5.2 | 7.4 45.3 205 26 13 9.7 5.3
13500 7.8 46.0 205 27 14 9.5 5.2 | 8.9 48.0 205 25 13 9.7 5.3
13000 9.3 48.7 200 27 14 9.6 5.3 | 10.3 50.5 205 24 12 9.7 5.3
12500 10.7 51.3 200 26 14 9.7 5.3 | 11.8 53.2 205 22 12 9.7 5.3
12000 12.0 53.6 195 25 13 9.0 4.9 | 13.2 55.8 205 21 11 9.2 5.0
11500 13.4 56.1 195 24 12 9.0 5.0 | 14.5 58.1 205 19 10 9.2 5.1
11000 14.7 58.5 190 23 12 8.5 4.7 | 15.9 60.6 200 17 9 8.9 4.9
10500 15.9 60.6 185 21 11 9.0 4.9 | 17.2 63.0 205 16 8 9.6 5.3
10250 16.6 61.9 180 20 10 9.5 5.2 | 18.0 64.4 205 15 8 10.7 5.9
10000 17.2 63.0 180 18 9 9.0 4.9 | 18.7 65.7 205 14 7 10.2 5.6
9750 17.8 64.0 170 15 8 8.7 4.8 | 19.5 67.1 205 14 7 9.9 5.4
9500 18.4 65.1 165 13 7 9.0 5.0 | 20.2 68.4 205 13 7 10.1 5.5
9250 19.0 66.2 155 12 6 8.5 4.7 | 21.0 69.8 205 12 6 9.6 5.3
9000 19.5 67.1 150 11 6 8.4 4.6 | 21.6 70.9 210 12 6 9.0 5.0
8750 20.1 68.2 145 10 5 9.2 5.0 | 22.3 72.1 210 11 6 9.3 5.1
8500 20.8 69.4 135 10 5 8.4 4.6 | 23.0 73.4 210 11 6 8.6 4.7
8250 21.4 70.5 130 9 5 11.0 6.0 | 23.7 74.7 215 10 5 11.2 6.2
8000 22.2 72.0 125 9 5 10.7 5.9 | 24.6 76.3 215 10 5 11.3 6.2
7750 22.9 73.2 125 9 5 8.3 4.5 | 25.3 77.5 220 9 5 8.8 4.8
7500 23.5 74.3 125 9 5 8.4 4.6 | 26.0 78.8 225 9 4 9.6 5.3
7250 24.2 75.6 125 9 4 10.5 5.7 | 26.6 79.9 225 8 4 9.0 4.9
7000 25.1 77.2 120 9 4 11.7 6.4 | 27.3 81.1 230 8 4 9.1 5.0
6750 25.8 78.4 120 8 4 9.2 5.1 | 28.0 82.4 235 8 4 10.1 5.6
6500 26.5 79.7 120 8 4 8.7 4.8 | 28.8 83.8 235 7 4 10.4 5.7
6250 27.2 81.0 120 8 4 10.7 5.9 | 29.6 85.3 240 7 4 10.1 5.6
6000 28.1 82.6 120 8 4 12.6 6.9 | 30.3 86.5 245 7 4 10.1 5.6
5750 29.0 84.2 115 8 4 10.4 5.7 | 31.1 88.0 250 7 3 10.6 5.8
5500 29.8 85.6 115 7 4 16.2 8.9 | 32.0 89.6 255 6 3 13.8 7.6
________________________________________________________________________________
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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