- 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 251232
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0532 MST Thursday, February 25, 2021
This forecast is for Thursday, February 25, 2021:
If the trigger temperature of 30.0 F/-1.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 406 ft/min (2.1 m/s)
Maximum height of thermals.................. 10762 ft MSL (5477 ft AGL)
Forecast maximum temperature................... 33.0 F/1.0 C
Time of trigger temperature.................... 1145 MST
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................. 8042 ft MSL (2757 ft AGL)
Thermal soaring outlook for Friday 02/26....... Fair
Wave Soaring Index............................. Good
Wave Soaring Index trend (to 1700 MST)......... No change
Height of stable layer (12-18K ft MSL)......... 13388 ft MSL (8103 ft AGL)
Weak PVA/NVA (through 1700 MST)................ Weak NVA
Potential height of wave....................... 15107 ft MSL (9822 ft AGL)
Wave soaring outlook for Friday 02/26.......... Good
Remarks...
Sunrise/Sunset.................... 06:37:36 / 17:47:16 MST
Total possible sunshine........... 11 hr 9 min 39 sec (669 min 39 sec)
Altitude of sun at 12:12:26 MST... 41.35 degrees
Upper air data from rawinsonde observation taken on 02/25/2021 at 0500 MST
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 9298 ft MSL (4013 ft AGL)
Lifted condensation level....... 9997 ft MSL (4712 ft AGL)
Lifted index.................... +8.7
K index......................... +7.1
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 -55.7 -68.3 260 65 33 3.9 2.1 110.8 231.5 62.4 M M
45000 -55.1 -67.2 260 62 32 3.7 2.0 86.6 187.9 52.1 M M
40000 -52.1 -61.8 270 55 28 1.7 0.9 67.2 153.0 43.3 M M
38000 -50.9 -59.6 265 52 27 3.2 1.8 60.2 140.3 39.8 M M
36000 -49.4 -56.9 255 48 25 -1.4 -0.8 53.7 128.7 36.4 M M
34000 -50.1 -58.2 260 53 27 -1.2 -0.6 44.3 111.7 30.7 M M
32000 -50.5 -58.9 260 55 28 4.1 2.2 35.5 95.9 25.2 M M
30000 -48.0 -54.4 255 57 29 4.2 2.3 31.0 87.8 22.5 M M
29000 -46.7 -52.1 255 58 30 4.4 2.4 28.7 83.6 21.1 M M
28000 -45.4 -49.7 255 62 32 4.4 2.4 26.5 79.7 19.7 M M
27000 -43.7 -46.7 250 67 35 4.6 2.6 24.0 75.2 18.1 M M
26000 -42.9 -45.2 250 71 36 1.8 1.0 21.3 70.4 16.2 M M
25000 -42.4 -44.3 250 67 34 1.8 1.0 18.3 65.0 14.1 M M
24000 -40.6 -41.1 245 67 34 7.2 4.0 16.9 62.4 13.1 M M
23000 -38.4 -37.1 240 65 34 7.7 4.2 16.1 60.9 12.6 M M
22000 -36.1 -33.0 235 62 32 7.7 4.2 15.4 59.7 12.2 M M
21000 -33.8 -28.8 240 58 30 7.7 4.2 14.6 58.3 11.6 M M
20000 -31.5 -24.7 245 54 28 7.7 4.2 13.9 57.1 11.2 M M
19500 -30.4 -22.7 250 53 27 7.7 4.2 13.5 56.3 10.9 M M
19000 -29.2 -20.6 250 52 27 7.7 4.2 13.1 55.6 10.6 M M
18500 -28.1 -18.6 255 51 26 7.7 4.2 12.7 54.9 10.4 M M
18000 -26.9 -16.4 255 51 26 8.1 4.4 12.4 54.3 10.1 M M
17500 -25.7 -14.3 255 50 26 8.1 4.5 12.1 53.8 9.9 M M
17000 -24.5 -12.1 255 49 25 8.1 4.5 11.8 53.3 9.7 M M
16500 -23.3 -9.9 255 49 25 8.1 4.5 11.5 52.8 9.5 M M
16000 -22.1 -7.8 255 48 25 8.1 4.5 11.3 52.4 9.4 M M
15500 -20.9 -5.6 250 43 22 8.0 4.4 11.0 51.9 9.2 M M
15000 -19.7 -3.5 245 37 19 5.4 3.0 10.8 51.4 8.9 M M
14500 -19.7 -3.5 240 34 17 -1.6 -0.9 9.1 48.5 7.5 M M
14000 -20.0 -4.0 230 28 15 -1.5 -0.8 6.4 43.5 5.1 M M
13500 -20.2 -4.4 215 23 12 -2.2 -1.2 4.5 40.2 3.5 M M
13000 -19.9 -3.8 195 20 11 6.5 3.6 3.2 37.8 2.3 M M
12500 -19.0 -2.2 190 18 9 6.3 3.5 2.7 36.8 1.8 M M
12000 -18.0 -0.4 190 16 8 6.3 3.5 2.1 35.9 1.3 M M
11500 -17.1 1.2 180 14 7 6.3 3.5 1.5 34.8 0.7 M M
11000 -16.2 2.8 170 13 7 6.3 3.5 1.0 33.8 0.2 M M
10500 -15.3 4.5 160 12 6 6.3 3.5 0.5 32.8 -0.3 378 1.9
10250 -14.8 5.4 155 12 6 6.3 3.5 0.2 32.3 -0.6 356 1.8
10000 -14.3 6.3 150 12 6 6.2 3.4 -0.1 31.9 -0.8 335 1.7
9750 -13.9 7.0 145 11 6 6.1 3.4 -0.4 31.4 -1.1 314 1.6
9500 -13.4 7.9 140 11 6 6.1 3.4 -0.6 30.9 -1.4 293 1.5
9250 -13.0 8.6 135 10 5 6.1 3.4 -0.9 30.4 -1.7 272 1.4
9000 -12.5 9.5 130 10 5 6.1 3.4 -1.2 29.9 -1.9 252 1.3
8750 -12.1 10.2 115 9 4 6.1 3.4 -1.5 29.4 -2.2 231 1.2
8500 -11.6 11.1 100 8 4 6.1 3.4 -1.7 28.9 -2.5 210 1.1
8250 -11.2 11.8 080 8 4 6.1 3.4 -2.0 28.4 -2.8 189 1.0
8000 -10.7 12.7 065 9 5 6.1 3.4 -2.3 27.9 -3.1 168 0.9
7750 -10.3 13.5 060 9 5 6.1 3.4 -2.6 27.4 -3.4 147 0.7
7500 -9.8 14.4 055 9 5 6.1 3.4 -2.9 26.9 -3.7 126 0.6
7250 -9.4 15.1 055 9 5 6.1 3.4 -3.1 26.4 -3.9 105 0.5
7000 -8.9 16.0 050 9 5 6.1 3.4 -3.4 25.9 -4.2 84 0.4
6750 -8.5 16.7 045 9 5 6.1 3.4 -3.7 25.4 -4.5 63 0.3
6500 -8.0 17.6 040 9 5 6.1 3.4 -4.0 24.8 -4.8 42 0.2
6250 -7.5 18.5 035 10 5 6.2 3.4 -4.3 24.3 -5.1 21 0.1
6000 -7.1 19.2 030 10 5 6.1 3.3 -4.5 23.9 -5.4 0 0.0
5750 -6.6 20.1 020 8 4 7.2 3.9 -4.8 23.4 -5.7 M M
5500 -6.1 21.0 005 6 3 9.1 5.0 -4.9 23.2 -5.9 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
02/25/2021 at 0800 MST | 02/25/2021 at 1100 MST
|
CAPE... +11.2 LI... +6.2 | CAPE... +11.0 LI... +4.3
CINH... 0.0 K Index... +5.7 | CINH... -0.7 K Index... -2.2
|
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 -56.6 -69.9 260 27 14 1.7 0.9 | -57.0 -70.6 265 25 13 1.6 0.9
45000 -54.1 -65.4 260 27 14 1.7 0.9 | -54.6 -66.3 270 24 12 1.6 0.9
40000 -52.0 -61.6 265 22 11 1.4 0.8 | -53.4 -64.1 285 14 7 0.7 0.4
38000 -51.1 -60.0 270 20 10 1.2 0.7 | -52.8 -63.0 300 12 6 2.1 1.2
36000 -50.3 -58.5 270 19 10 1.2 0.7 | -51.5 -60.7 320 13 7 2.2 1.2
34000 -49.6 -57.3 275 18 9 1.1 0.6 | -50.2 -58.4 335 16 8 2.0 1.1
32000 -48.3 -54.9 275 18 9 2.2 1.2 | -48.0 -54.4 350 16 8 3.9 2.1
30000 -47.0 -52.6 275 17 9 2.0 1.1 | -45.7 -50.3 360 17 9 3.8 2.1
29000 -46.0 -50.8 275 17 9 3.8 2.1 | -44.2 -47.6 005 16 8 5.5 3.0
28000 -44.9 -48.8 270 17 9 3.8 2.1 | -42.1 -43.8 010 16 8 5.5 3.0
27000 -43.7 -46.7 265 17 9 3.8 2.1 | -40.5 -40.9 010 16 8 5.4 3.0
26000 -42.5 -44.5 265 17 9 5.1 2.8 | -39.0 -38.2 005 14 7 4.5 2.5
25000 -40.9 -41.6 260 18 9 5.0 2.8 | -37.6 -35.7 355 11 6 4.5 2.5
24000 -39.4 -38.9 255 19 10 5.0 2.8 | -36.3 -33.3 335 9 5 4.5 2.5
23000 -37.9 -36.2 255 19 10 5.7 3.1 | -35.1 -31.2 310 8 4 3.6 2.0
22000 -36.2 -33.2 250 20 10 5.6 3.1 | -34.0 -29.2 285 9 4 3.6 2.0
21000 -34.5 -30.1 245 21 11 5.6 3.1 | -32.9 -27.2 270 10 5 3.5 1.9
20000 -32.5 -26.5 245 20 10 7.3 4.0 | -31.5 -24.7 265 11 6 5.3 2.9
19500 -31.4 -24.5 250 19 10 7.3 4.0 | -30.7 -23.3 265 12 6 5.3 2.9
19000 -30.3 -22.5 250 18 9 7.4 4.0 | -29.9 -21.8 265 13 7 5.3 2.9
18500 -29.2 -20.6 255 17 9 7.3 4.0 | -29.1 -20.4 260 13 7 5.2 2.8
18000 -27.4 -17.3 260 15 8 9.3 5.1 | -28.2 -18.8 260 14 7 7.5 4.1
17500 -26.0 -14.8 255 14 7 9.3 5.1 | -27.0 -16.6 260 14 7 7.9 4.3
17000 -24.7 -12.5 260 14 7 8.5 4.7 | -25.9 -14.6 260 14 7 8.4 4.6
16500 -23.4 -10.1 260 13 7 8.5 4.6 | -24.5 -12.1 265 14 7 9.1 5.0
16000 -22.2 -8.0 260 12 6 8.5 4.7 | -23.2 -9.8 265 13 7 9.1 5.0
15500 -20.9 -5.6 260 12 6 8.5 4.7 | -21.8 -7.2 265 13 7 9.1 5.0
15000 -19.6 -3.3 260 11 6 7.9 4.3 | -19.8 -3.6 270 13 7 9.1 5.0
14500 -18.6 -1.5 260 11 6 6.8 3.7 | -18.4 -1.1 270 12 6 9.1 5.0
14000 -17.5 0.5 260 11 6 6.0 3.3 | -17.1 1.2 270 11 6 8.5 4.7
13500 -17.0 1.4 255 10 5 3.0 1.6 | -16.0 3.2 270 10 5 7.2 3.9
13000 -16.5 2.3 245 10 5 2.4 1.3 | -14.9 5.2 270 9 5 6.3 3.5
12500 -16.5 2.3 235 9 5 -0.6 -0.3 | -14.3 6.3 270 8 4 3.7 2.0
12000 -16.6 2.1 220 9 4 0.2 0.1 | -13.7 7.3 265 7 4 2.7 1.5
11500 -16.3 2.7 210 9 4 2.6 1.4 | -13.6 7.5 250 7 3 -0.2 -0.1
11000 -16.0 3.2 195 9 5 4.0 2.2 | -13.7 7.3 240 6 3 0.3 0.2
10500 -15.0 5.0 195 8 4 6.6 3.6 | -13.5 7.7 215 7 4 1.1 0.6
10250 -14.5 5.9 195 8 4 7.0 3.9 | -13.5 7.7 205 8 4 1.1 0.6
10000 -14.1 6.6 195 8 4 2.9 1.6 | -13.4 7.9 200 9 4 1.7 0.9
9750 -14.0 6.8 195 7 4 3.9 2.1 | -13.1 8.4 195 9 5 5.2 2.9
9500 -13.4 7.9 200 7 4 8.8 4.8 | -12.6 9.3 195 9 5 7.4 4.0
9250 -12.8 9.0 200 6 3 7.0 3.9 | -12.1 10.2 190 9 5 6.7 3.7
9000 -12.4 9.7 200 6 3 5.1 2.8 | -11.7 10.9 190 9 5 6.2 3.4
8750 -12.0 10.4 200 6 3 5.2 2.9 | -11.2 11.8 185 9 5 7.3 4.0
8500 -11.6 11.1 190 6 3 6.2 3.4 | -10.6 12.9 185 8 4 9.1 5.0
8250 -11.1 12.0 185 5 3 5.9 3.2 | -9.9 14.2 185 7 4 7.4 4.0
8000 -10.7 12.7 175 5 2 5.1 2.8 | -9.5 14.9 180 6 3 6.1 3.3
7750 -10.3 13.5 165 5 2 6.7 3.7 | -9.0 15.8 180 4 2 6.3 3.4
7500 -9.8 14.4 150 5 2 7.7 4.2 | -8.6 16.5 175 3 2 7.5 4.1
7250 -9.3 15.3 145 4 2 6.6 3.6 | -7.9 17.8 170 3 1 9.4 5.2
7000 -8.8 16.2 135 3 2 6.5 3.5 | -7.2 19.0 170 2 1 9.7 5.3
6750 -8.3 17.1 125 3 1 6.8 3.7 | -6.5 20.3 165 2 1 9.4 5.2
6500 -7.8 18.0 110 2 1 8.5 4.6 | -5.8 21.6 165 2 1 9.7 5.3
6250 -7.1 19.2 095 2 1 9.4 5.1 | -5.1 22.8 165 2 1 10.2 5.6
6000 -6.4 20.5 070 1 1 9.3 5.1 | -4.3 24.3 165 2 1 9.8 5.4
5750 -5.7 21.7 040 1 0 11.5 6.3 | -3.5 25.7 165 2 1 14.2 7.8
5500 -4.7 23.5 035 1 0 14.6 8.0 | -2.1 28.2 165 2 1 22.1 12.1
02/25/2021 at 1400 MST | 02/25/2021 at 1700 MST
|
CAPE... +4.3 LI... +4.1 | CAPE... 0.0 LI... +8.0
CINH... 0.0 K Index... -1.4 | CINH... 0.0 K Index... -7.9
|
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 -58.1 -72.6 270 26 13 1.3 0.7 | -60.0 -76.0 265 28 14 0.4 0.2
45000 -56.1 -69.0 275 25 13 1.3 0.7 | -59.4 -74.9 265 25 13 0.4 0.2
40000 -56.5 -69.7 310 18 9 -0.5 -0.3 | -60.7 -77.3 300 22 12 -1.0 -0.5
38000 -56.3 -69.3 330 18 9 3.5 1.9 | -60.1 -76.2 315 23 12 6.1 3.4
36000 -53.9 -65.0 350 22 11 3.5 1.9 | -56.3 -69.3 320 22 12 6.3 3.5
34000 -51.8 -61.2 360 26 14 4.7 2.6 | -52.0 -61.6 330 22 11 7.2 3.9
32000 -47.9 -54.2 005 26 13 6.5 3.6 | -47.6 -53.7 335 22 11 7.4 4.1
30000 -44.0 -47.2 015 25 13 6.2 3.4 | -43.1 -45.6 335 21 11 7.4 4.0
29000 -42.3 -44.1 015 24 12 5.6 3.1 | -40.9 -41.6 340 20 10 7.3 4.0
28000 -40.6 -41.1 015 22 11 5.6 3.1 | -38.7 -37.7 345 19 10 7.3 4.0
27000 -39.0 -38.2 020 21 11 5.6 3.1 | -36.5 -33.7 350 18 9 7.4 4.0
26000 -37.1 -34.8 020 20 10 6.8 3.8 | -34.6 -30.3 355 17 9 5.7 3.1
25000 -35.0 -31.0 025 20 10 6.9 3.8 | -32.9 -27.2 360 15 8 5.7 3.1
24000 -32.9 -27.2 030 19 10 6.9 3.8 | -31.2 -24.2 005 14 7 5.7 3.1
23000 -31.0 -23.8 030 18 9 5.5 3.0 | -29.3 -20.7 010 13 7 7.0 3.9
22000 -29.4 -20.9 025 16 8 5.6 3.1 | -27.2 -17.0 015 12 6 7.1 3.9
21000 -27.7 -17.9 020 14 7 5.7 3.1 | -25.1 -13.2 020 12 6 7.1 3.9
20000 -26.7 -16.1 005 10 5 2.0 1.1 | -23.2 -9.8 020 11 5 5.9 3.2
19500 -26.4 -15.5 355 8 4 1.9 1.1 | -22.3 -8.1 020 10 5 5.9 3.2
19000 -26.1 -15.0 340 7 4 1.9 1.1 | -21.4 -6.5 020 10 5 5.9 3.2
18500 -25.8 -14.4 315 7 4 1.9 1.1 | -20.6 -5.1 020 9 5 6.0 3.3
18000 -25.2 -13.4 295 8 4 4.3 2.4 | -19.8 -3.6 020 9 4 2.3 1.3
17500 -24.5 -12.1 285 8 4 4.0 2.2 | -19.6 -3.3 355 7 4 0.7 0.4
17000 -23.8 -10.8 280 9 4 6.2 3.4 | -19.5 -3.1 335 7 4 1.0 0.5
16500 -22.8 -9.0 275 10 5 6.6 3.6 | -19.3 -2.7 320 7 4 1.1 0.6
16000 -21.9 -7.4 275 11 5 6.8 3.7 | -19.2 -2.6 305 8 4 2.3 1.3
15500 -20.8 -5.4 275 12 6 6.9 3.8 | -18.6 -1.5 290 9 5 4.0 2.2
15000 -19.8 -3.6 275 13 7 7.3 4.0 | -18.1 -0.6 280 10 5 4.4 2.4
14500 -18.7 -1.7 270 13 7 8.2 4.5 | -17.3 0.9 275 11 6 5.8 3.2
14000 -17.5 0.5 270 13 7 8.2 4.5 | -16.5 2.3 270 12 6 6.0 3.3
13500 -16.2 2.8 270 12 6 8.4 4.6 | -15.5 4.1 265 12 6 7.5 4.1
13000 -15.0 5.0 270 11 6 8.4 4.6 | -14.4 6.1 265 11 6 7.4 4.1
12500 -13.8 7.2 275 10 5 7.9 4.3 | -13.3 8.1 270 10 5 8.0 4.4
12000 -12.6 9.3 275 9 5 7.6 4.2 | -12.1 10.2 270 10 5 7.9 4.4
11500 -11.8 10.8 275 8 4 3.8 2.1 | -11.0 12.2 270 9 5 6.9 3.8
11000 -11.3 11.7 280 7 3 4.3 2.4 | -10.0 14.0 270 8 4 6.9 3.8
10500 -10.5 13.1 275 6 3 5.6 3.1 | -9.1 15.6 270 7 4 5.7 3.1
10250 -10.0 14.0 270 6 3 6.5 3.5 | -8.6 16.5 265 7 3 6.4 3.5
10000 -9.6 14.7 265 5 3 2.8 1.5 | -8.2 17.2 265 6 3 4.2 2.3
9750 -9.6 14.7 260 5 3 0.1 0.0 | -8.0 17.6 260 6 3 3.3 1.8
9500 -9.5 14.9 240 5 2 1.8 1.0 | -7.7 18.1 260 5 3 4.5 2.5
9250 -9.4 15.1 225 5 3 1.3 0.7 | -7.3 18.9 255 5 2 4.8 2.6
9000 -9.3 15.3 210 5 3 2.6 1.4 | -7.0 19.4 245 4 2 2.4 1.3
8750 -9.0 15.8 200 4 2 5.9 3.2 | -6.9 19.6 230 3 2 2.4 1.3
8500 -8.5 16.7 190 4 2 7.3 4.0 | -6.6 20.1 215 3 1 4.8 2.6
8250 -8.0 17.6 175 3 2 7.6 4.2 | -6.3 20.7 195 2 1 4.7 2.6
8000 -7.4 18.7 165 3 2 8.8 4.8 | -5.9 21.4 175 3 1 7.4 4.0
7750 -6.7 19.9 165 3 1 9.3 5.1 | -5.3 22.5 170 3 1 8.7 4.8
7500 -6.0 21.2 160 3 1 9.7 5.3 | -4.6 23.7 165 3 2 8.3 4.6
7250 -5.3 22.5 160 3 1 10.2 5.6 | -4.0 24.8 165 3 2 8.9 4.9
7000 -4.5 23.9 160 3 1 10.9 6.0 | -3.3 26.1 160 3 2 9.5 5.2
6750 -3.7 25.3 160 3 1 9.5 5.2 | -2.6 27.3 160 3 2 9.0 4.9
6500 -3.0 26.6 160 2 1 9.5 5.2 | -1.9 28.6 160 3 2 9.3 5.1
6250 -2.2 28.0 160 2 1 11.0 6.1 | -1.2 29.8 155 3 1 10.4 5.7
6000 -1.4 29.5 160 2 1 10.2 5.6 | -0.4 31.3 155 2 1 10.9 6.0
5750 -0.6 30.9 160 2 1 12.5 6.8 | 0.4 32.7 155 2 1 9.7 5.3
5500 0.5 32.9 160 2 1 18.9 10.3 | 1.0 33.8 155 2 1 7.5 4.1
________________________________________________________________________________
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