Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
223
UXUS97 KBOU 061324
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0723 MDT Monday, May 6, 2024
This forecast is for Monday, May 6, 2024:
If the trigger temperature of 55.3 F/12.9 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 481 ft/min (2.4 m/s)
Maximum height of thermals.................. 11567 ft MSL (6332 ft AGL)
Forecast maximum temperature................... 60.0 F/16.0 C
Time of trigger temperature.................... 1230 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 7592 ft MSL (2356 ft AGL)
Thermal soaring outlook for Tuesday 05/07...... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Becoming good by 1200 MDT
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak NVA
Potential height of wave....................... 26619 ft MSL (21384 ft AGL)
Wave soaring outlook for Tuesday 05/07......... Fair
Remarks... Strong westerly flow aloft and mountain wave from late this morning
through tonight. Mountain wave weakens Tuesday but winds stay strong.
Sunrise/Sunset.................... 05:53:01 / 19:59:05 MDT
Total possible sunshine........... 14 hr 6 min 5 sec (846 min 5 sec)
Altitude of sun at 12:56:03 MDT... 67.05 degrees
Upper air data from numerical model forecast valid on 05/06/2024 at 0600 MDT
Freezing level.................. 9696 ft MSL (4461 ft AGL)
Convective condensation level... 16801 ft MSL (11566 ft AGL)
Lifted condensation level....... 14518 ft MSL (9282 ft AGL)
Lifted index.................... +5.4
K index......................... -13.1
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 -53.0 -63.4 230 29 15 3.3 1.8 M M M M M
45000 -48.0 -54.4 225 44 22 1.3 0.7 M M M M M
40000 -49.8 -57.6 205 62 32 -1.2 -0.6 M M M M M
38000 -49.9 -57.8 205 68 35 0.9 0.5 M M M M M
36000 -49.3 -56.7 200 71 37 0.9 0.5 M M M M M
34000 -48.6 -55.5 195 75 38 4.9 2.7 M M M M M
32000 -45.0 -49.0 195 75 39 6.0 3.3 M M M M M
30000 -41.4 -42.5 195 76 39 6.9 3.8 35.7 96.3 15.1 M M
29000 -39.2 -38.6 195 77 39 7.2 4.0 34.6 94.2 14.4 M M
28000 -37.0 -34.6 195 77 40 7.2 4.0 33.5 92.4 13.8 M M
27000 -34.9 -30.8 195 78 40 7.2 3.9 32.7 90.8 13.3 M M
26000 -32.4 -26.3 200 78 40 6.3 3.5 31.2 88.1 12.4 M M
25000 -30.5 -22.9 200 79 40 6.3 3.5 29.9 85.7 11.4 M M
24000 -28.6 -19.5 205 79 41 6.3 3.5 28.7 83.6 10.6 M M
23000 -26.4 -15.5 210 79 41 7.9 4.3 27.8 82.0 10.0 M M
22000 -24.0 -11.2 210 79 41 7.9 4.3 27.0 80.7 9.5 M M
21000 -21.7 -7.1 215 79 41 8.0 4.4 26.5 79.6 9.2 M M
20000 -19.5 -3.1 215 76 39 6.9 3.8 25.5 77.9 8.4 M M
19500 -18.5 -1.3 215 74 38 6.9 3.8 25.0 76.9 8.0 M M
19000 -17.5 0.5 215 72 37 6.9 3.8 24.5 76.1 7.7 M M
18500 -16.4 2.5 215 70 36 6.9 3.8 24.0 75.2 7.3 M M
18000 -15.4 4.3 215 68 35 6.2 3.4 23.5 74.3 6.9 M M
17500 -14.5 5.9 215 63 33 6.1 3.3 22.9 73.2 6.4 M M
17000 -13.6 7.5 215 59 30 6.2 3.4 22.3 72.1 5.9 M M
16500 -12.6 9.3 215 55 28 6.9 3.8 21.7 71.1 5.4 M M
16000 -11.6 11.1 215 52 27 7.1 3.9 21.2 70.2 5.0 M M
15500 -10.7 12.7 215 49 25 4.1 2.2 20.6 69.0 4.4 M M
15000 -10.1 13.8 220 49 25 4.1 2.3 19.6 67.3 3.6 M M
14500 -9.5 14.9 225 48 25 5.6 3.1 18.7 65.7 2.8 M M
14000 -8.6 16.5 225 47 24 6.4 3.5 18.2 64.7 2.3 M M
13500 -7.6 18.3 230 46 24 6.0 3.3 17.6 63.8 1.8 M M
13000 -6.8 19.8 230 44 23 5.4 2.9 16.9 62.4 1.1 M M
12500 -6.1 21.0 235 42 22 6.2 3.4 16.2 61.2 0.4 M M
12000 -4.9 23.2 235 38 20 9.0 5.0 15.9 60.7 0.2 M M
11500 -3.0 26.6 235 32 17 6.7 3.7 15.6 60.2 -0.1 463 2.3
11000 -2.1 28.2 245 34 18 6.2 3.4 15.1 59.1 -0.7 421 2.1
10500 -1.2 29.8 245 37 19 5.4 3.0 14.5 58.0 -1.3 380 1.9
10250 -0.8 30.6 250 38 20 5.6 3.1 14.1 57.4 -1.7 362 1.8
10000 -0.4 31.3 250 39 20 6.5 3.6 13.8 56.9 -2.0 341 1.7
9750 0.1 32.2 250 39 20 7.2 4.0 13.6 56.5 -2.2 319 1.6
9500 0.6 33.1 250 39 20 8.0 4.4 13.4 56.2 -2.4 295 1.5
9250 1.2 34.2 255 39 20 8.4 4.6 13.3 56.0 -2.5 270 1.4
9000 1.8 35.2 255 39 20 7.8 4.3 13.2 55.7 -2.7 245 1.2
8750 2.4 36.3 255 38 20 8.6 4.7 13.0 55.5 -2.8 220 1.1
8500 3.1 37.6 255 38 20 9.9 5.4 13.0 55.4 -2.9 192 1.0
8250 3.8 38.8 250 38 19 10.0 5.5 13.0 55.5 -2.9 163 0.8
8000 4.6 40.3 250 37 19 9.2 5.1 13.0 55.5 -2.9 133 0.7
7750 5.2 41.4 250 37 19 8.9 4.9 13.0 55.3 -3.0 107 0.5
7500 5.9 42.6 250 36 18 9.3 5.1 12.9 55.3 -3.0 78 0.4
7250 6.6 43.9 250 35 18 9.6 5.3 12.9 55.2 -3.1 50 0.3
7000 7.3 45.1 250 34 18 8.2 4.5 12.9 55.2 -3.1 22 0.1
6750 7.8 46.0 250 34 17 8.2 4.5 12.7 54.9 -3.3 M M
6500 8.5 47.3 245 32 16 9.4 5.2 12.7 54.8 -3.4 M M
6250 9.2 48.6 245 30 15 9.6 5.3 12.6 54.7 -3.4 M M
6000 9.8 49.6 240 27 14 6.4 3.5 12.6 54.6 -3.5 M M
5750 10.1 50.2 240 24 12 1.9 1.0 12.1 53.7 -4.0 M M
5500 10.2 50.4 240 19 10 3.5 1.9 11.5 52.7 -4.6 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/06/2024 at 0900 MDT | 05/06/2024 at 1200 MDT
|
CAPE... 0.0 LI... +5.8 | CAPE... +4.1 LI... +0.8
CINH... 0.0 K Index... -6.9 | CINH... -32.1 K Index... +10.9
|
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 -52.1 -61.8 250 29 15 3.7 2.0 | -52.2 -62.0 235 19 10 2.8 1.5
45000 -46.6 -51.9 250 26 14 2.5 1.4 | -48.0 -54.4 255 9 5 2.7 1.5
40000 -45.1 -49.2 220 48 24 0.9 0.5 | -44.0 -47.2 235 39 20 2.6 1.4
38000 -45.1 -49.2 215 55 28 -1.4 -0.7 | -42.9 -45.2 235 46 24 0.5 0.3
36000 -45.9 -50.6 205 60 31 -1.3 -0.7 | -42.6 -44.7 225 46 24 0.5 0.3
34000 -46.7 -52.1 200 66 34 -0.4 -0.2 | -42.3 -44.1 220 47 24 0.4 0.2
32000 -45.1 -49.2 195 71 37 3.0 1.7 | -40.6 -41.1 220 44 23 3.1 1.7
30000 -43.2 -45.8 195 76 39 3.4 1.9 | -38.8 -37.8 220 42 21 3.0 1.7
29000 -41.5 -42.7 195 77 40 6.3 3.5 | -37.8 -36.0 225 41 21 3.4 1.8
28000 -39.6 -39.3 195 79 40 6.3 3.5 | -36.5 -33.7 225 40 21 3.4 1.8
27000 -37.7 -35.9 190 80 41 6.3 3.5 | -35.5 -31.9 225 39 20 3.3 1.8
26000 -35.7 -32.3 190 80 41 7.3 4.0 | -35.0 -31.0 225 38 20 -1.9 -1.1
25000 -33.6 -28.5 190 78 40 7.3 4.0 | -35.4 -31.7 225 35 18 -1.5 -0.8
24000 -30.8 -23.4 195 76 39 7.3 4.0 | -35.9 -32.6 230 32 17 -1.5 -0.8
23000 -28.6 -19.5 195 74 38 7.7 4.2 | -35.9 -32.6 230 29 15 5.6 3.1
22000 -26.3 -15.3 190 72 37 7.7 4.2 | -34.3 -29.7 230 24 12 5.4 3.0
21000 -24.0 -11.2 190 69 36 7.8 4.3 | -32.7 -26.9 225 19 10 5.5 3.0
20000 -22.1 -7.8 190 65 34 5.7 3.2 | -30.6 -23.1 220 15 8 9.1 5.0
19500 -21.2 -6.2 190 62 32 5.7 3.1 | -29.2 -20.6 220 13 7 9.1 5.0
19000 -20.3 -4.5 190 60 31 5.7 3.1 | -27.9 -18.2 215 11 6 9.1 5.0
18500 -19.5 -3.1 190 57 29 5.7 3.1 | -26.5 -15.7 215 9 5 9.1 5.0
18000 -18.7 -1.7 195 54 28 3.5 1.9 | -25.2 -13.4 210 7 4 8.7 4.8
17500 -18.4 -1.1 195 48 25 2.0 1.1 | -24.0 -11.2 220 7 3 7.9 4.3
17000 -18.1 -0.6 205 43 22 2.1 1.1 | -22.8 -9.0 235 7 4 7.9 4.3
16500 -17.4 0.7 205 38 20 7.0 3.9 | -21.6 -6.9 250 7 4 8.1 4.5
16000 -16.4 2.5 210 35 18 6.5 3.6 | -20.4 -4.7 265 8 4 8.1 4.4
15500 -15.3 4.5 210 31 16 8.4 4.6 | -19.2 -2.6 275 10 5 9.1 5.0
15000 -14.0 6.8 215 29 15 8.6 4.7 | -17.7 0.1 275 13 7 9.4 5.1
14500 -12.7 9.1 220 26 13 8.3 4.6 | -16.3 2.7 280 16 8 9.3 5.1
14000 -11.5 11.3 225 21 11 8.1 4.4 | -14.3 6.3 280 21 11 9.3 5.1
13500 -10.3 13.5 235 17 9 7.9 4.3 | -13.0 8.6 280 24 12 7.9 4.4
13000 -9.2 15.4 250 16 8 7.6 4.1 | -11.8 10.8 280 27 14 7.9 4.3
12500 -8.1 17.4 260 15 8 7.6 4.1 | -10.7 12.7 280 31 16 6.9 3.8
12000 -7.0 19.4 265 20 10 7.5 4.1 | -9.7 14.5 280 33 17 6.7 3.7
11500 -5.9 21.4 270 26 14 7.4 4.0 | -8.7 16.3 275 34 18 7.3 4.0
11000 -4.9 23.2 270 32 16 6.7 3.7 | -7.6 18.3 275 33 17 7.4 4.1
10500 -3.9 25.0 275 37 19 6.3 3.4 | -6.5 20.3 275 31 16 8.5 4.6
10250 -3.5 25.7 275 39 20 4.6 2.5 | -5.8 21.6 275 30 16 8.7 4.8
10000 -3.1 26.4 275 41 21 4.2 2.3 | -5.2 22.6 275 29 15 9.6 5.3
9750 -2.8 27.0 275 43 22 5.4 3.0 | -4.4 24.1 275 29 15 10.5 5.8
9500 -2.4 27.7 275 44 23 5.8 3.2 | -3.6 25.5 275 28 15 10.3 5.6
9250 -2.0 28.4 275 44 23 5.0 2.8 | -2.8 27.0 275 28 14 11.0 6.0
9000 -1.6 29.1 275 43 22 5.1 2.8 | -2.1 28.2 275 27 14 8.6 4.7
8750 -0.9 30.4 275 40 20 7.7 4.2 | -1.5 29.3 275 27 14 8.3 4.5
8500 -0.2 31.6 275 39 20 9.7 5.3 | -0.8 30.6 275 26 14 10.6 5.8
8250 0.5 32.9 275 38 20 9.3 5.1 | -0.0 32.0 275 26 13 9.5 5.2
8000 1.2 34.2 275 37 19 9.0 4.9 | 0.7 33.3 275 25 13 11.4 6.3
7750 1.9 35.4 275 37 19 9.7 5.3 | 1.6 34.9 275 25 13 10.8 5.9
7500 2.6 36.7 275 36 18 10.4 5.7 | 2.3 36.1 275 24 13 8.6 4.7
7250 3.4 38.1 275 35 18 11.4 6.3 | 3.0 37.4 275 24 12 9.0 4.9
7000 4.2 39.6 275 34 18 6.7 3.7 | 3.7 38.7 275 24 12 9.8 5.4
6750 4.6 40.3 275 33 17 7.7 4.2 | 4.4 39.9 275 23 12 10.7 5.9
6500 5.5 41.9 275 32 17 13.5 7.4 | 5.2 41.4 275 22 12 10.3 5.7
6250 6.4 43.5 275 31 16 11.2 6.2 | 6.0 42.8 275 22 11 10.3 5.6
6000 7.1 44.8 275 29 15 7.7 4.2 | 6.7 44.1 275 21 11 9.9 5.4
5750 7.6 45.7 275 27 14 7.1 3.9 | 7.4 45.3 275 20 10 9.1 5.0
5500 8.5 47.3 275 23 12 18.2 10.0 | 8.2 46.8 275 17 9 14.2 7.8
05/06/2024 at 1500 MDT | 05/06/2024 at 1800 MDT
|
CAPE... +52.0 LI... -0.5 | CAPE... 0.0 LI... +0.9
CINH... -9.3 K Index... +10.4 | CINH... 0.0 K Index... +8.9
|
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 -51.0 -59.8 220 18 9 2.1 1.1 | -50.5 -58.9 240 19 10 1.7 1.0
45000 -47.8 -54.0 220 18 9 2.1 1.2 | -47.9 -54.2 255 21 11 1.8 1.0
40000 -44.4 -47.9 245 38 20 2.2 1.2 | -45.0 -49.0 265 31 16 1.9 1.0
38000 -43.5 -46.3 250 42 21 0.7 0.4 | -44.3 -47.7 265 33 17 -0.3 -0.2
36000 -43.0 -45.4 245 37 19 0.8 0.4 | -44.5 -48.1 265 31 16 -0.3 -0.1
34000 -42.6 -44.7 245 33 17 0.7 0.4 | -44.6 -48.3 265 28 14 -0.3 -0.2
32000 -41.7 -43.1 250 30 15 1.5 0.8 | -45.0 -49.0 285 23 12 -0.6 -0.3
30000 -40.8 -41.4 260 28 14 1.6 0.9 | -45.3 -49.5 315 23 12 -0.3 -0.2
29000 -40.8 -41.4 270 25 13 -0.6 -0.3 | -44.3 -47.7 320 24 12 4.6 2.5
28000 -41.0 -41.8 290 22 12 -0.6 -0.3 | -42.9 -45.2 320 25 13 4.6 2.5
27000 -41.2 -42.2 310 23 12 -0.5 -0.3 | -41.5 -42.7 320 26 14 4.6 2.5
26000 -40.5 -40.9 315 24 12 7.8 4.3 | -39.8 -39.6 320 26 14 7.6 4.2
25000 -38.3 -36.9 310 24 12 7.4 4.1 | -37.6 -35.7 310 25 13 7.5 4.1
24000 -36.0 -32.8 305 23 12 7.4 4.1 | -35.3 -31.5 295 25 13 7.5 4.1
23000 -34.0 -29.2 290 23 12 5.8 3.2 | -33.2 -27.8 285 26 13 6.5 3.5
22000 -32.2 -26.0 265 23 12 5.9 3.3 | -31.2 -24.2 275 25 13 6.6 3.6
21000 -30.4 -22.7 245 27 14 5.9 3.3 | -29.3 -20.7 265 26 13 6.6 3.6
20000 -28.6 -19.5 240 27 14 6.3 3.4 | -27.1 -16.8 265 25 13 7.8 4.3
19500 -27.7 -17.9 240 25 13 6.3 3.4 | -25.3 -13.5 270 23 12 7.8 4.3
19000 -26.8 -16.2 245 23 12 6.3 3.5 | -24.2 -11.6 275 22 11 7.8 4.3
18500 -25.8 -14.4 250 21 11 6.4 3.5 | -23.0 -9.4 280 21 11 7.7 4.2
18000 -24.9 -12.8 255 19 10 7.7 4.2 | -21.7 -7.1 285 20 10 9.4 5.1
17500 -23.5 -10.3 265 18 9 9.2 5.0 | -20.3 -4.5 290 19 10 9.2 5.1
17000 -22.2 -8.0 275 18 9 9.2 5.1 | -19.0 -2.2 295 19 10 8.8 4.8
16500 -20.8 -5.4 280 20 10 8.8 4.9 | -17.7 0.1 300 20 10 8.5 4.7
16000 -19.5 -3.1 285 22 11 8.9 4.9 | -16.4 2.5 300 21 11 8.6 4.7
15500 -18.1 -0.6 290 25 13 9.3 5.1 | -15.1 4.8 300 23 12 8.6 4.7
15000 -16.0 3.2 295 29 15 9.4 5.2 | -13.8 7.2 300 25 13 8.7 4.8
14500 -14.7 5.5 295 32 16 8.1 4.4 | -12.6 9.3 300 27 14 7.7 4.2
14000 -13.5 7.7 295 35 18 8.2 4.5 | -11.5 11.3 295 30 15 7.8 4.3
13500 -12.3 9.9 290 38 19 8.3 4.5 | -10.3 13.5 295 33 17 7.6 4.2
13000 -11.1 12.0 290 41 21 8.4 4.6 | -9.2 15.4 290 36 19 7.6 4.2
12500 -9.9 14.2 290 42 22 7.2 4.0 | -8.1 17.4 290 39 20 7.0 3.8
12000 -8.9 16.0 285 42 21 7.1 3.9 | -7.1 19.2 285 42 21 7.0 3.8
11500 -7.8 18.0 285 40 21 8.6 4.7 | -6.1 21.0 285 44 22 7.0 3.9
11000 -6.5 20.3 280 36 19 8.8 4.8 | -5.0 23.0 280 44 23 7.0 3.9
10500 -5.2 22.6 280 33 17 9.2 5.1 | -4.0 24.8 280 43 22 7.5 4.1
10250 -4.5 23.9 280 32 17 9.4 5.1 | -3.4 25.9 275 42 22 7.7 4.2
10000 -3.8 25.2 280 31 16 9.3 5.1 | -2.8 27.0 275 41 21 8.4 4.6
9750 -3.1 26.4 280 31 16 10.1 5.5 | -2.2 28.0 275 39 20 9.3 5.1
9500 -2.3 27.9 280 30 16 10.8 6.0 | -1.5 29.3 275 38 20 9.4 5.2
9250 -1.5 29.3 280 30 15 11.5 6.3 | -0.8 30.6 275 36 19 9.7 5.3
9000 -0.6 30.9 280 29 15 8.9 4.9 | -0.0 32.0 275 35 18 8.7 4.8
8750 -0.1 31.8 280 29 15 9.0 4.9 | 0.6 33.1 275 34 17 8.7 4.8
8500 0.8 33.4 280 28 15 11.5 6.3 | 1.3 34.3 275 33 17 10.0 5.5
8250 1.6 34.9 280 28 14 11.7 6.4 | 2.0 35.6 275 32 16 8.9 4.9
8000 2.4 36.3 280 27 14 8.4 4.6 | 2.7 36.9 275 31 16 11.9 6.5
7750 2.9 37.2 280 27 14 7.7 4.2 | 3.7 38.7 275 29 15 11.5 6.3
7500 3.7 38.7 280 27 14 10.8 6.0 | 4.4 39.9 275 29 15 8.5 4.7
7250 4.4 39.9 280 26 13 9.9 5.4 | 5.1 41.2 275 28 14 9.2 5.1
7000 5.2 41.4 280 26 13 10.6 5.8 | 5.7 42.3 275 27 14 9.3 5.1
6750 6.0 42.8 280 25 13 10.6 5.8 | 6.5 43.7 275 26 13 9.9 5.5
6500 6.7 44.1 280 25 13 9.9 5.4 | 7.2 45.0 275 25 13 10.0 5.5
6250 7.5 45.5 280 24 12 10.6 5.8 | 8.0 46.4 275 24 12 10.1 5.5
6000 8.3 46.9 280 23 12 10.7 5.9 | 8.8 47.8 275 23 12 11.4 6.3
5750 9.2 48.6 280 22 11 16.8 9.2 | 9.6 49.3 275 21 11 9.8 5.4
5500 10.9 51.6 280 20 10 28.5 15.6 | 10.2 50.4 275 18 9 9.5 5.2
________________________________________________________________________________
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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