- Warnings
- Observations
- Forecasts
- Text Messages
- Forecast Models
- Climate
- Weather Safety
- Education/Outreach
- Information Center
- Contact Us
RSS Feeds
Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 061314
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0713 MDT Thursday, May 6, 2021
This forecast is for Thursday, May 6, 2021:
If the trigger temperature of 61.0 F/16.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 809 ft/min (4.1 m/s)
Maximum height of thermals.................. 15168 ft MSL (9883 ft AGL)
Forecast maximum temperature................... 72.0 F/22.7 C
Time of trigger temperature.................... 1230 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................. 12084 ft MSL (6798 ft AGL)
Thermal soaring outlook for Friday 05/07....... Excellent
Wave Soaring Index............................. Good
Wave Soaring Index trend (to 1800 MDT)......... Becoming poor
Height of stable layer (12-18K ft MSL)......... 15124 ft MSL (9839 ft AGL)
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 43410 ft MSL (38125 ft AGL)
Wave soaring outlook for Friday 05/07.......... Poor
Remarks...
Sunrise/Sunset.................... 05:53:19 / 19:58:49 MDT
Total possible sunshine........... 14 hr 5 min 29 sec (845 min 29 sec)
Altitude of sun at 12:56:04 MDT... 66.97 degrees
Upper air data from rawinsonde observation taken on 05/06/2021 at 0600 MDT
Freezing level.................. 11358 ft MSL (6073 ft AGL)
Convective condensation level... 13128 ft MSL (7843 ft AGL)
Lifted condensation level....... 14252 ft MSL (8967 ft AGL)
Lifted index.................... +0.8
K index......................... -5.8
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 -60.1 -76.2 305 49 25 1.0 0.5 99.3 210.7 44.1 M M
45000 -59.3 -74.7 305 71 36 -3.6 -2.0 74.6 166.4 32.2 M M
40000 -64.0 -83.2 320 70 36 5.8 3.2 44.4 111.9 14.6 M M
38000 -59.5 -75.1 315 65 34 7.9 4.4 42.1 107.8 13.5 M M
36000 -54.7 -66.5 310 64 33 8.5 4.7 40.7 105.3 12.9 M M
34000 -50.1 -58.2 310 62 32 6.6 3.6 39.0 102.2 12.0 M M
32000 -46.2 -51.2 310 59 30 6.4 3.5 36.2 97.2 10.3 M M
30000 -40.4 -40.7 310 55 28 8.8 4.8 35.3 95.6 9.9 M M
29000 -37.8 -36.0 310 54 28 8.8 4.8 34.7 94.4 9.5 M M
28000 -35.2 -31.4 310 52 27 8.8 4.8 34.2 93.5 9.3 M M
27000 -32.5 -26.5 310 51 26 8.8 4.8 33.8 92.9 9.1 M M
26000 -29.9 -21.8 310 50 26 8.8 4.8 33.6 92.4 9.0 M M
25000 -27.3 -17.1 310 49 25 8.8 4.8 33.4 92.1 9.0 M M
24000 -24.6 -12.3 310 49 25 7.7 4.2 33.0 91.4 8.7 M M
23000 -22.2 -8.0 310 49 25 8.1 4.4 32.2 90.0 8.2 M M
22000 -19.8 -3.6 310 50 26 8.1 4.4 31.6 88.9 7.8 M M
21000 -17.4 0.7 310 50 26 8.1 4.4 31.1 87.9 7.4 M M
20000 -15.0 5.0 310 50 26 7.9 4.4 30.7 87.2 7.1 M M
19500 -13.8 7.2 315 49 25 6.0 3.3 30.3 86.6 6.9 M M
19000 -13.7 7.3 320 49 25 0.3 0.2 28.8 83.8 5.5 M M
18500 -13.0 8.6 320 48 25 6.0 3.3 27.8 82.1 4.7 M M
18000 -12.2 10.0 320 47 24 5.8 3.2 27.1 80.8 4.1 M M
17500 -11.3 11.7 325 46 24 5.7 3.1 26.5 79.6 3.6 M M
17000 -10.6 12.9 325 45 23 4.8 2.6 25.7 78.3 2.9 M M
16500 -9.8 14.4 325 43 22 4.9 2.7 24.9 76.8 2.2 M M
16000 -9.0 15.8 320 40 20 5.0 2.7 24.1 75.3 1.6 M M
15500 -8.3 17.1 315 39 20 5.3 2.9 23.3 73.9 0.9 M M
15000 -7.8 18.0 310 38 20 3.8 2.1 21.4 70.5 -0.9 802 4.1
14500 -6.7 19.9 310 38 20 7.1 3.9 21.0 69.9 -1.3 754 3.8
14000 -5.7 21.7 305 37 19 7.4 4.1 20.7 69.2 -1.6 707 3.6
13500 -4.6 23.7 305 33 17 7.4 4.1 20.3 68.5 -2.0 659 3.3
13000 -3.5 25.7 305 29 15 7.4 4.1 19.9 67.8 -2.4 612 3.1
12500 -2.4 27.7 310 25 13 7.4 4.1 19.5 67.1 -2.8 564 2.9
12000 -1.3 29.7 310 20 10 7.4 4.1 19.2 66.5 -3.1 516 2.6
11500 -0.2 31.6 305 16 8 7.4 4.1 18.8 65.8 -3.5 469 2.4
11000 0.9 33.6 300 12 6 7.4 4.1 18.4 65.1 -3.9 421 2.1
10500 2.0 35.6 285 9 5 7.5 4.1 18.0 64.4 -4.3 373 1.9
10250 2.6 36.7 270 7 4 8.6 4.7 17.9 64.1 -4.5 348 1.8
10000 3.2 37.8 235 6 3 6.3 3.5 17.7 63.9 -4.6 323 1.6
9750 3.5 38.3 220 5 2 4.2 2.3 17.3 63.2 -5.1 307 1.6
9500 3.8 38.8 200 4 2 4.5 2.5 16.9 62.4 -5.5 291 1.5
9250 4.1 39.4 175 4 2 5.8 3.2 16.5 61.7 -6.0 274 1.4
9000 4.4 39.9 155 4 2 0.6 0.3 16.1 61.0 -6.4 258 1.3
8750 4.0 39.2 145 3 1 -2.7 -1.5 15.1 59.3 -7.6 262 1.3
8500 3.9 39.0 125 1 1 3.0 1.6 14.4 58.0 -8.4 257 1.3
8250 4.2 39.6 065 1 1 4.1 2.3 14.0 57.1 -8.8 241 1.2
8000 4.5 40.1 025 2 1 3.8 2.1 13.5 56.3 -9.3 225 1.1
7750 4.8 40.6 010 3 2 3.9 2.2 13.1 55.5 -9.8 209 1.1
7500 5.1 41.2 360 4 2 3.7 2.1 12.6 54.7 -10.3 193 1.0
7250 5.4 41.7 360 5 3 4.4 2.4 12.2 53.9 -10.7 177 0.9
7000 5.5 41.9 355 6 3 -4.2 -2.3 11.6 52.8 -11.4 166 0.8
6750 4.8 40.6 355 6 3 -10.6 -5.8 10.1 50.1 -12.8 180 0.9
6500 4.1 39.4 350 6 3 -10.7 -5.9 8.6 47.5 -14.3 194 1.0
6250 3.4 38.1 350 7 3 -1.7 -0.9 7.2 45.0 -15.7 206 1.0
6000 3.8 38.8 350 7 4 7.6 4.2 6.9 44.4 -16.1 187 0.9
5750 4.2 39.6 335 6 3 4.5 2.5 6.6 43.8 -16.5 167 0.9
5500 4.6 40.3 315 6 3 7.6 4.2 6.3 43.3 -16.9 148 0.8
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/06/2021 at 0900 MDT | 05/06/2021 at 1200 MDT
|
CAPE... +0.3 LI... +6.3 | CAPE... 0.0 LI... +4.6
CINH... -0.1 K Index... -1.2 | CINH... -0.2 K Index... -1.0
|
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 -61.1 -78.0 305 24 12 1.3 0.7 | -62.7 -80.9 305 23 12 1.6 0.9
45000 -59.6 -75.3 310 31 16 -1.5 -0.8 | -60.6 -77.1 310 29 15 0.2 0.1
40000 -62.0 -79.6 320 30 15 -2.2 -1.2 | -60.3 -76.5 305 26 14 -0.6 -0.3
38000 -58.3 -72.9 315 29 15 7.8 4.3 | -56.8 -70.2 305 26 13 6.9 3.8
36000 -53.7 -64.7 310 28 15 7.8 4.3 | -52.7 -62.9 300 25 13 6.9 3.8
34000 -49.2 -56.6 310 27 14 7.2 4.0 | -48.3 -54.9 300 25 13 7.6 4.2
32000 -44.3 -47.7 305 25 13 7.2 4.0 | -43.2 -45.8 300 24 12 7.6 4.2
30000 -39.7 -39.5 300 24 12 7.9 4.3 | -38.8 -37.8 295 23 12 7.3 4.0
29000 -37.4 -35.3 300 23 12 7.9 4.3 | -36.6 -33.9 295 23 12 7.3 4.0
28000 -35.0 -31.0 295 23 12 7.9 4.3 | -34.5 -30.1 295 22 12 7.2 4.0
27000 -32.6 -26.7 295 23 12 8.3 4.6 | -32.2 -26.0 295 22 11 7.6 4.1
26000 -30.1 -22.2 295 22 12 8.3 4.6 | -30.0 -22.0 295 22 11 7.6 4.1
25000 -27.6 -17.7 295 22 11 8.3 4.6 | -27.7 -17.9 295 22 11 7.6 4.2
24000 -25.2 -13.4 295 22 11 8.0 4.4 | -25.4 -13.7 295 21 11 7.9 4.4
23000 -22.8 -9.0 300 21 11 8.0 4.4 | -23.0 -9.4 300 20 10 8.0 4.4
22000 -20.4 -4.7 305 21 11 8.0 4.4 | -20.7 -5.3 300 19 10 8.0 4.4
21000 -18.2 -0.8 305 21 11 7.2 4.0 | -18.3 -0.9 300 19 10 7.8 4.3
20000 -16.0 3.2 310 20 10 7.2 4.0 | -16.0 3.2 300 18 9 7.8 4.3
19500 -14.9 5.2 310 20 10 7.3 4.0 | -14.9 5.2 300 18 9 7.8 4.3
19000 -13.9 7.0 310 20 10 7.2 4.0 | -13.7 7.3 300 18 9 7.8 4.3
18500 -12.3 9.9 310 20 10 7.1 3.9 | -12.0 10.4 305 18 9 7.7 4.2
18000 -11.2 11.8 310 19 10 6.9 3.8 | -10.8 12.6 305 17 9 7.6 4.2
17500 -10.2 13.6 310 19 10 6.5 3.6 | -9.7 14.5 300 17 9 7.4 4.0
17000 -9.3 15.3 310 18 9 6.6 3.6 | -8.6 16.5 300 17 9 7.4 4.1
16500 -8.3 17.1 310 18 9 5.7 3.1 | -7.5 18.5 300 16 8 7.1 3.9
16000 -7.5 18.5 310 17 9 5.8 3.2 | -6.5 20.3 300 16 8 7.2 3.9
15500 -6.6 20.1 310 16 8 5.8 3.2 | -5.4 22.3 300 16 8 6.5 3.6
15000 -5.8 21.6 310 15 8 5.8 3.2 | -4.5 23.9 300 15 8 6.3 3.5
14500 -4.9 23.2 310 15 7 5.9 3.2 | -3.6 25.5 300 15 8 6.3 3.4
14000 -4.0 24.8 310 14 7 6.1 3.4 | -2.6 27.3 295 14 7 6.3 3.4
13500 -3.1 26.4 310 13 7 6.2 3.4 | -1.7 28.9 295 13 7 6.4 3.5
13000 -2.2 28.0 310 12 6 6.7 3.7 | -0.7 30.7 295 12 6 6.9 3.8
12500 -1.2 29.8 310 11 6 6.8 3.7 | 0.3 32.5 295 12 6 6.9 3.8
12000 -0.2 31.6 310 10 5 7.2 3.9 | 1.3 34.3 295 11 5 7.0 3.9
11500 0.9 33.6 310 9 5 7.1 3.9 | 2.3 36.1 295 10 5 7.0 3.8
11000 1.9 35.4 310 8 4 6.6 3.6 | 3.3 37.9 295 8 4 6.3 3.4
10500 2.9 37.2 305 8 4 6.4 3.5 | 4.2 39.6 295 7 4 5.9 3.2
10250 3.3 37.9 305 7 4 4.3 2.3 | 4.5 40.1 295 6 3 4.1 2.2
10000 3.6 38.5 305 7 3 5.1 2.8 | 4.9 40.8 300 6 3 5.4 3.0
9750 4.0 39.2 305 6 3 7.1 3.9 | 5.4 41.7 300 5 3 7.4 4.1
9500 4.5 40.1 300 6 3 5.7 3.1 | 5.9 42.6 300 4 2 6.0 3.3
9250 4.9 40.8 300 5 3 4.2 2.3 | 6.2 43.2 300 4 2 4.2 2.3
9000 5.1 41.2 295 5 3 3.6 2.0 | 6.5 43.7 305 3 2 3.7 2.0
8750 5.4 41.7 295 4 2 3.6 2.0 | 6.8 44.2 305 2 1 4.1 2.3
8500 5.6 42.1 295 4 2 2.4 1.3 | 7.0 44.6 310 1 1 3.4 1.9
8250 5.7 42.3 295 4 2 1.2 0.6 | 7.2 45.0 325 1 1 2.4 1.3
8000 5.8 42.4 295 3 2 1.6 0.9 | 7.4 45.3 350 1 0 3.1 1.7
7750 5.8 42.4 290 3 1 -0.2 -0.1 | 7.7 45.9 000 0 0 5.7 3.1
7500 5.6 42.1 290 2 1 -2.2 -1.2 | 8.1 46.6 000 0 0 5.4 3.0
7250 5.5 41.9 295 2 1 -2.0 -1.1 | 8.4 47.1 070 1 0 3.9 2.1
7000 5.3 41.5 300 2 1 -2.7 -1.5 | 8.6 47.5 080 1 0 4.2 2.3
6750 5.1 41.2 305 2 1 0.1 0.1 | 9.0 48.2 080 1 1 8.7 4.8
6500 5.2 41.4 305 1 1 2.8 1.5 | 9.8 49.6 080 1 1 11.1 6.1
6250 5.3 41.5 310 1 1 3.4 1.8 | 10.5 50.9 075 1 1 10.0 5.5
6000 5.5 41.9 315 2 1 -0.7 -0.4 | 11.3 52.3 075 1 1 8.8 4.8
5750 5.4 41.7 320 1 1 3.4 1.9 | 12.0 53.6 075 1 1 15.2 8.3
5500 6.3 43.3 320 1 1 22.9 12.5 | 13.7 56.7 070 1 1 30.7 16.9
05/06/2021 at 1500 MDT | 05/06/2021 at 1800 MDT
|
CAPE... +0.4 LI... +2.3 | CAPE... +45.4 LI... +0.5
CINH... -0.8 K Index... +8.0 | CINH... -66.8 K Index... +15.3
|
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 -62.2 -80.0 300 21 11 1.3 0.7 | -62.1 -79.8 300 20 11 1.1 0.6
45000 -60.4 -76.7 305 25 13 -0.0 -0.0 | -60.6 -77.1 300 23 12 0.6 0.3
40000 -60.4 -76.7 290 24 13 -0.9 -0.5 | -59.6 -75.3 290 21 11 0.0 0.0
38000 -56.6 -69.9 295 24 12 7.3 4.0 | -56.3 -69.3 290 20 10 6.4 3.5
36000 -52.3 -62.1 295 23 12 7.3 4.0 | -52.5 -62.5 290 20 10 6.4 3.5
34000 -47.4 -53.3 295 22 12 7.3 4.0 | -47.8 -54.0 290 20 10 7.4 4.1
32000 -43.0 -45.4 295 22 11 7.2 4.0 | -43.4 -46.1 290 20 10 7.4 4.1
30000 -38.6 -37.5 295 22 11 7.5 4.1 | -38.8 -37.8 295 20 10 7.7 4.2
29000 -36.3 -33.3 295 22 11 7.5 4.1 | -36.5 -33.7 295 20 10 7.7 4.2
28000 -34.1 -29.4 295 22 11 7.5 4.1 | -34.2 -29.6 295 19 10 7.7 4.2
27000 -31.9 -25.4 295 21 11 7.5 4.1 | -32.0 -25.6 295 19 10 7.6 4.2
26000 -29.6 -21.3 295 21 11 7.5 4.1 | -29.7 -21.5 295 19 10 7.6 4.2
25000 -27.4 -17.3 300 21 11 7.5 4.1 | -27.4 -17.3 295 19 10 7.7 4.2
24000 -25.1 -13.2 300 20 10 7.8 4.3 | -25.1 -13.2 295 19 10 7.8 4.3
23000 -22.8 -9.0 300 19 10 7.8 4.3 | -22.8 -9.0 295 18 9 7.8 4.3
22000 -20.4 -4.7 300 19 10 7.8 4.3 | -20.4 -4.7 295 18 9 7.8 4.3
21000 -18.1 -0.6 300 18 9 7.7 4.2 | -18.1 -0.6 295 18 9 7.6 4.2
20000 -15.8 3.6 295 17 9 7.7 4.2 | -15.3 4.5 290 17 9 7.6 4.2
19500 -14.7 5.5 295 17 9 7.7 4.2 | -14.2 6.4 290 17 9 7.6 4.2
19000 -13.0 8.6 295 17 9 7.6 4.2 | -13.0 8.6 290 17 9 7.7 4.2
18500 -11.8 10.8 295 17 9 7.6 4.2 | -11.9 10.6 285 17 9 7.7 4.2
18000 -10.7 12.7 295 16 8 7.7 4.2 | -10.8 12.6 285 16 8 7.9 4.3
17500 -9.6 14.7 295 16 8 7.7 4.2 | -9.6 14.7 285 16 8 8.2 4.5
17000 -8.4 16.9 290 16 8 7.7 4.2 | -8.4 16.9 285 16 8 8.2 4.5
16500 -7.3 18.9 290 16 8 7.8 4.3 | -7.1 19.2 285 16 8 8.6 4.7
16000 -6.1 21.0 290 15 8 7.8 4.3 | -5.9 21.4 285 15 8 8.5 4.7
15500 -5.0 23.0 285 15 8 7.9 4.3 | -4.6 23.7 285 15 8 8.6 4.7
15000 -3.8 25.2 285 15 8 8.0 4.4 | -3.3 26.1 280 15 8 8.7 4.8
14500 -2.6 27.3 285 15 8 8.0 4.4 | -2.1 28.2 280 14 7 8.7 4.8
14000 -1.4 29.5 285 14 7 8.0 4.4 | -0.8 30.6 280 13 7 8.6 4.7
13500 -0.3 31.5 280 14 7 8.0 4.4 | 0.5 32.9 280 13 6 8.6 4.7
13000 0.9 33.6 280 13 6 7.8 4.3 | 1.7 35.1 280 12 6 8.2 4.5
12500 2.0 35.6 280 12 6 7.7 4.2 | 2.9 37.2 280 10 5 8.2 4.5
12000 3.0 37.4 275 10 5 6.5 3.6 | 4.0 39.2 275 9 5 7.3 4.0
11500 4.0 39.2 275 9 4 6.6 3.6 | 5.1 41.2 270 8 4 7.4 4.0
11000 4.8 40.6 270 7 4 5.3 2.9 | 6.1 43.0 260 6 3 6.5 3.6
10500 5.6 42.1 260 5 3 4.6 2.5 | 7.0 44.6 245 5 3 5.7 3.1
10250 5.8 42.4 255 5 2 2.7 1.5 | 7.3 45.1 240 5 2 4.1 2.3
10000 6.1 43.0 250 4 2 5.2 2.9 | 7.7 45.9 230 4 2 6.7 3.7
9750 6.6 43.9 245 3 2 7.4 4.1 | 8.3 46.9 225 3 2 8.6 4.7
9500 7.1 44.8 230 2 1 6.6 3.6 | 8.9 48.0 210 3 1 7.8 4.3
9250 7.5 45.5 210 2 1 5.2 2.9 | 9.4 48.9 195 2 1 5.6 3.1
9000 7.9 46.2 190 1 1 6.8 3.7 | 9.8 49.6 175 2 1 7.1 3.9
8750 8.5 47.3 160 1 1 9.1 5.0 | 10.5 50.9 165 2 1 9.8 5.4
8500 9.1 48.4 125 1 1 8.2 4.5 | 11.1 52.0 145 2 1 8.7 4.8
8250 9.7 49.5 115 1 1 7.6 4.2 | 11.7 53.1 135 2 1 7.7 4.2
8000 10.3 50.5 105 2 1 8.4 4.6 | 12.3 54.1 125 2 1 8.3 4.5
7750 11.0 51.8 100 2 1 10.5 5.8 | 13.0 55.4 120 2 1 10.4 5.7
7500 11.7 53.1 100 2 1 10.0 5.5 | 13.8 56.8 115 2 1 9.7 5.3
7250 12.4 54.3 095 2 1 8.6 4.7 | 14.4 57.9 110 2 1 8.4 4.6
7000 13.1 55.6 090 2 1 9.4 5.2 | 15.1 59.2 105 2 1 9.0 4.9
6750 13.9 57.0 090 2 1 11.7 6.4 | 15.8 60.4 105 2 1 11.2 6.1
6500 14.8 58.6 085 2 1 11.3 6.2 | 16.7 62.1 100 2 1 11.1 6.1
6250 15.5 59.9 085 2 1 10.0 5.5 | 17.4 63.3 095 2 1 9.9 5.4
6000 16.3 61.3 080 2 1 9.7 5.3 | 18.2 64.8 095 2 1 9.6 5.3
5750 17.1 62.8 075 2 1 15.6 8.6 | 18.9 66.0 090 2 1 11.1 6.1
5500 18.7 65.7 070 2 1 27.8 15.3 | 19.9 67.8 090 2 1 16.1 8.8
________________________________________________________________________________
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
- National Weather Service
- Denver/Boulder, CO Weather Forecast Office
- 325 Broadway
- Boulder, CO 80305-3328
- 303-494-4221
- Page Author: BOU Webmaster
- Web Master's E-mail: w-bou.webmaster@noaa.gov
- Page last modified: Feb 1st, 2021 20:13 UTC