- 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 170145
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1945 MDT Thursday, May 16, 2013
This forecast is for Friday, May 17, 2013:
If the trigger temperature of 76.5 F/24.7 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1436 ft/min (7.3 m/s)
Maximum height of thermals.................. 20211 ft MSL (14924 ft AGL)
Forecast maximum temperature................... 86.0 F/30.5 C
Time of trigger temperature.................... 1030 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................. 16455 ft MSL (11167 ft AGL)
Thermal soaring outlook for Saturday 05/18..... Excellent
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)................ Weak NVA
Potential height of wave....................... 45611 ft MSL (40324 ft AGL)
Wave soaring outlook for Saturday 05/18........ Poor
Remarks...
Sunrise/Sunset.................... 05:42:59 / 20:08:37 MDT
Total possible sunshine........... 14 hr 25 min 38 sec (865 min 38 sec)
Altitude of sun at 12:55:59 MDT... 69.71 degrees
Upper air data from numerical model forecast valid on 05/17/2013 at 0600 MDT
Freezing level.................. 14056 ft MSL (8769 ft AGL)
Convective condensation level... 16957 ft MSL (11670 ft AGL)
Lifted condensation level....... 18236 ft MSL (12948 ft AGL)
Lifted index.................... -1.9
K index......................... +16.7
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 -61.8 -79.2 255 21 11 -2.3 -1.3 M M M M M
45000 -64.9 -84.8 250 32 17 2.4 1.3 M M M M M
40000 -61.6 -78.9 245 24 13 1.5 0.8 M M M M M
38000 -57.1 -70.8 245 25 13 8.1 4.5 M M M M M
36000 -52.3 -62.1 240 27 14 8.1 4.5 M M M M M
34000 -47.4 -53.3 240 28 14 8.1 4.5 M M M M M
32000 -42.5 -44.5 245 27 14 8.1 4.5 M M M M M
30000 -37.6 -35.7 250 27 14 8.2 4.5 38.2 100.7 6.2 M M
29000 -34.5 -30.1 250 27 14 8.2 4.5 37.4 99.3 5.7 M M
28000 -32.1 -25.8 255 27 14 8.2 4.5 36.9 98.4 5.3 M M
27000 -29.7 -21.5 255 27 14 7.8 4.3 36.2 97.1 4.8 M M
26000 -27.4 -17.3 255 27 14 7.8 4.3 35.4 95.7 4.3 M M
25000 -25.0 -13.0 250 26 14 7.8 4.3 34.7 94.5 3.8 M M
24000 -22.7 -8.9 250 26 13 7.5 4.1 34.0 93.2 3.2 M M
23000 -20.5 -4.9 250 25 13 7.5 4.1 33.1 91.6 2.5 M M
22000 -18.2 -0.8 245 25 13 7.5 4.1 32.4 90.3 1.9 M M
21000 -16.2 2.8 245 23 12 6.1 3.3 31.3 88.3 1.0 M M
20000 -14.5 5.9 235 20 10 6.0 3.3 29.9 85.9 -0.2 1422 7.2
19500 -13.6 7.5 230 19 10 6.1 3.3 29.3 84.8 -0.8 1381 7.0
19000 -12.7 9.1 230 18 9 6.3 3.5 28.7 83.7 -1.3 1340 6.8
18500 -11.7 10.9 225 17 9 7.6 4.2 28.3 82.9 -1.7 1294 6.6
18000 -10.6 12.9 225 15 8 7.5 4.1 27.9 82.2 -2.1 1246 6.3
17500 -9.5 14.9 225 15 8 8.2 4.5 27.6 81.6 -2.5 1198 6.1
17000 -8.2 17.2 230 15 7 8.4 4.6 27.3 81.2 -2.7 1146 5.8
16500 -7.0 19.4 230 15 7 8.6 4.7 27.1 80.8 -2.9 1094 5.6
16000 -5.7 21.7 235 15 8 8.9 4.9 26.9 80.5 -3.1 1040 5.3
15500 -4.4 24.1 240 15 8 8.9 4.9 26.8 80.3 -3.3 986 5.0
15000 -3.0 26.6 245 15 8 9.3 5.1 26.7 80.1 -3.4 930 4.7
14500 -1.0 30.2 245 15 8 9.3 5.1 26.6 79.8 -3.5 846 4.3
14000 0.5 32.9 250 15 8 9.8 5.4 26.5 79.8 -3.6 789 4.0
13500 1.9 35.4 250 14 7 9.8 5.4 26.6 79.8 -3.6 730 3.7
13000 3.4 38.1 250 14 7 9.2 5.1 26.5 79.7 -3.7 673 3.4
12500 4.7 40.5 255 13 7 9.3 5.1 26.4 79.6 -3.8 617 3.1
12000 6.1 43.0 255 12 6 8.8 4.8 26.3 79.4 -3.9 561 2.9
11500 7.4 45.3 255 11 6 8.9 4.9 26.2 79.1 -4.1 507 2.6
11000 8.6 47.5 250 11 5 7.3 4.0 25.9 78.7 -4.3 456 2.3
10500 9.7 49.5 250 10 5 7.4 4.1 25.6 78.0 -4.7 409 2.1
10250 10.3 50.5 245 10 5 10.9 6.0 25.5 77.9 -4.8 383 1.9
10000 11.2 52.2 245 10 5 10.5 5.7 25.6 78.1 -4.7 350 1.8
9750 11.8 53.2 240 10 5 7.9 4.3 25.5 77.9 -4.9 324 1.6
9500 12.4 54.3 235 10 5 8.6 4.7 25.4 77.7 -5.0 298 1.5
9250 13.0 55.4 235 10 5 8.2 4.5 25.3 77.6 -5.1 272 1.4
9000 13.6 56.5 230 10 5 8.3 4.6 25.2 77.3 -5.2 246 1.3
8750 14.3 57.7 225 10 5 8.7 4.8 25.1 77.2 -5.4 220 1.1
8500 14.9 58.8 225 10 5 8.5 4.7 25.0 77.0 -5.5 194 1.0
8250 15.5 59.9 220 10 5 9.0 5.0 24.9 76.9 -5.6 167 0.9
8000 16.2 61.2 220 9 5 8.4 4.6 24.9 76.8 -5.7 140 0.7
7750 16.7 62.1 215 9 5 7.2 3.9 24.7 76.5 -5.9 117 0.6
7500 17.3 63.1 215 9 4 7.3 4.0 24.5 76.1 -6.1 93 0.5
7250 17.8 64.0 215 8 4 7.7 4.2 24.3 75.8 -6.3 70 0.4
7000 18.4 65.1 220 8 4 7.3 4.0 24.2 75.5 -6.4 45 0.2
6750 18.9 66.0 220 8 4 8.7 4.8 24.0 75.2 -6.6 21 0.1
6500 19.5 67.1 225 8 4 1.4 0.8 23.8 74.8 -6.9 M M
6250 19.0 66.2 220 9 4 -11.3 -6.2 22.6 72.7 -8.1 5 0.0
6000 18.0 64.4 220 9 5 -13.1 -7.2 20.9 69.6 -9.8 28 0.1
5750 16.8 62.2 215 10 5 -21.4 -11.7 19.0 66.2 -11.8 57 0.3
5500 14.0 57.2 215 11 6 -53.2 -29.2 15.6 60.2 -15.3 132 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/17/2013 at 0900 MDT | 05/17/2013 at 1200 MDT
|
K index... +13.9 LI... +2.5 | K index... +1.3 LI... +2.3
CAPE... 0.0 CIN... -0.3 | CAPE... 0.0 CIN... M
|
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 -62.4 -80.3 250 25 13 -1.6 -0.9 | -61.5 -78.7 255 22 11 -1.3 -0.7
45000 -64.3 -83.7 245 33 17 1.9 1.0 | -63.1 -81.6 245 32 16 1.1 0.6
40000 -61.4 -78.5 235 25 13 1.3 0.7 | -61.4 -78.5 235 32 16 0.4 0.2
38000 -57.3 -71.1 235 25 13 7.5 4.1 | -57.3 -71.1 235 31 16 7.7 4.2
36000 -52.8 -63.0 235 25 13 7.5 4.1 | -52.7 -62.9 235 30 15 7.7 4.2
34000 -48.0 -54.4 235 26 13 8.4 4.6 | -47.9 -54.2 230 29 15 8.2 4.5
32000 -42.9 -45.2 235 25 13 8.4 4.6 | -42.3 -44.1 225 30 15 8.2 4.5
30000 -37.3 -35.1 235 24 13 8.2 4.5 | -37.5 -35.5 225 29 15 8.1 4.4
29000 -34.8 -30.6 235 24 12 8.2 4.5 | -35.0 -31.0 220 29 15 8.1 4.4
28000 -32.4 -26.3 240 23 12 8.3 4.5 | -32.6 -26.7 220 29 15 8.1 4.4
27000 -29.9 -21.8 240 23 12 7.9 4.4 | -30.2 -22.4 220 29 15 7.8 4.3
26000 -27.6 -17.7 240 24 12 7.9 4.4 | -27.9 -18.2 220 30 15 7.8 4.3
25000 -25.2 -13.4 240 25 13 7.9 4.4 | -25.6 -14.1 220 30 16 7.8 4.3
24000 -22.8 -9.0 240 25 13 7.8 4.3 | -23.2 -9.8 220 30 15 7.9 4.3
23000 -20.5 -4.9 240 25 13 7.8 4.3 | -20.9 -5.6 225 29 15 7.9 4.3
22000 -18.1 -0.6 240 25 13 7.8 4.3 | -18.5 -1.3 230 29 15 7.9 4.3
21000 -15.8 3.6 240 24 13 7.6 4.2 | -16.0 3.2 230 28 14 8.5 4.6
20000 -13.6 7.5 240 23 12 7.7 4.2 | -13.5 7.7 235 26 13 8.5 4.7
19500 -12.4 9.7 235 22 12 7.6 4.2 | -12.2 10.0 235 25 13 8.5 4.6
19000 -11.3 11.7 235 22 11 7.2 4.0 | -10.9 12.4 240 24 12 8.3 4.5
18500 -10.4 13.3 230 22 11 5.8 3.2 | -9.8 14.4 240 23 12 7.6 4.2
18000 -9.5 14.9 225 22 11 6.0 3.3 | -8.6 16.5 240 22 11 7.7 4.2
17500 -8.7 16.3 220 22 11 6.1 3.3 | -7.5 18.5 240 21 11 7.1 3.9
17000 -7.8 18.0 210 22 11 6.3 3.4 | -6.5 20.3 235 21 11 7.0 3.8
16500 -7.0 19.4 205 22 11 7.3 4.0 | -5.4 22.3 235 20 10 7.1 3.9
16000 -5.7 21.7 200 21 11 9.2 5.1 | -4.4 24.1 230 20 10 7.4 4.1
15500 -4.3 24.3 200 21 11 9.3 5.1 | -2.7 27.1 220 20 10 7.7 4.2
15000 -2.3 27.9 200 19 10 8.9 4.9 | -1.5 29.3 215 20 10 8.0 4.4
14500 -1.0 30.2 205 17 9 8.8 4.8 | -0.4 31.3 210 20 10 8.1 4.4
14000 0.3 32.5 205 15 8 8.3 4.5 | 0.8 33.4 205 20 10 8.4 4.6
13500 1.5 34.7 210 13 7 8.3 4.5 | 2.1 35.8 205 20 10 8.4 4.6
13000 2.9 37.2 215 11 6 9.3 5.1 | 3.4 38.1 205 20 10 9.2 5.1
12500 4.3 39.7 220 10 5 9.2 5.1 | 4.7 40.5 200 19 10 9.3 5.1
12000 5.7 42.3 230 10 5 9.6 5.3 | 6.0 42.8 205 19 10 8.4 4.6
11500 7.1 44.8 240 10 5 9.7 5.3 | 7.3 45.1 205 18 9 8.7 4.8
11000 8.4 47.1 245 10 5 8.1 4.4 | 8.4 47.1 210 17 9 7.0 3.8
10500 9.6 49.3 245 10 5 8.9 4.9 | 9.4 48.9 210 15 8 7.8 4.3
10250 10.4 50.7 250 10 5 11.3 6.2 | 10.0 50.0 210 13 7 10.9 6.0
10000 11.2 52.2 250 10 5 9.9 5.5 | 10.9 51.6 215 11 6 10.6 5.8
9750 11.8 53.2 255 10 5 8.2 4.5 | 11.6 52.9 215 10 5 9.1 5.0
9500 12.5 54.5 255 10 5 8.7 4.8 | 12.2 54.0 215 9 5 9.7 5.3
9250 13.1 55.6 260 10 5 8.4 4.6 | 12.9 55.2 215 8 4 8.8 4.9
9000 13.7 56.7 260 10 5 8.5 4.7 | 13.6 56.5 220 8 4 9.2 5.0
8750 14.4 57.9 260 10 5 8.8 4.8 | 14.3 57.7 220 8 4 10.2 5.6
8500 15.0 59.0 260 10 5 8.6 4.7 | 15.1 59.2 220 7 4 9.8 5.4
8250 15.7 60.3 265 10 5 9.5 5.2 | 15.8 60.4 220 7 4 10.8 5.9
8000 16.4 61.5 265 10 5 8.7 4.8 | 16.6 61.9 220 7 4 10.7 5.9
7750 16.9 62.4 265 10 5 6.9 3.8 | 17.4 63.3 220 7 4 9.8 5.4
7500 17.5 63.5 265 10 5 7.4 4.1 | 18.1 64.6 220 7 3 10.0 5.5
7250 18.1 64.6 265 10 5 9.1 5.0 | 18.9 66.0 225 7 3 9.9 5.4
7000 18.8 65.8 265 10 5 9.3 5.1 | 19.6 67.3 225 6 3 9.9 5.4
6750 19.4 66.9 270 11 6 9.1 5.0 | 20.4 68.7 225 6 3 9.4 5.2
6500 20.0 68.0 275 11 6 5.7 3.1 | 21.1 70.0 225 6 3 10.2 5.6
6250 20.2 68.4 270 10 5 1.5 0.8 | 21.9 71.4 225 6 3 11.6 6.4
6000 20.2 68.4 270 9 5 1.0 0.5 | 22.7 72.9 230 6 3 11.4 6.3
5750 20.1 68.2 265 8 4 -1.3 -0.7 | 23.5 74.3 230 6 3 11.4 6.3
5500 19.9 67.8 245 6 3 2.2 1.2 | 24.6 76.3 230 5 3 17.5 9.6
05/17/2013 at 1500 MDT | 05/17/2013 at 1800 MDT
|
K index... +9.2 LI... +1.3 | K index... +13.4 LI... +0.6
CAPE... 0.0 CIN... -2.3 | CAPE... +1.1 CIN... -13.4
|
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 -61.2 -78.2 265 18 9 -1.4 -0.8 | -61.5 -78.7 260 16 8 -0.9 -0.5
45000 -63.0 -81.4 260 23 12 1.0 0.5 | -62.5 -80.5 245 21 11 0.9 0.5
40000 -61.5 -78.7 235 33 17 0.2 0.1 | -61.1 -78.0 245 33 17 0.2 0.1
38000 -57.2 -71.0 235 34 17 8.0 4.4 | -57.1 -70.8 245 34 17 7.7 4.2
36000 -52.4 -62.3 235 34 17 8.0 4.4 | -52.5 -62.5 245 34 17 7.7 4.2
34000 -47.6 -53.7 235 35 18 7.8 4.3 | -47.2 -53.0 240 36 18 7.9 4.3
32000 -42.4 -44.3 235 37 19 7.8 4.3 | -42.4 -44.3 240 40 20 7.9 4.3
30000 -37.6 -35.7 235 37 19 8.2 4.5 | -37.4 -35.3 235 40 21 8.6 4.7
29000 -35.1 -31.2 235 37 19 8.2 4.5 | -34.8 -30.6 235 39 20 8.6 4.7
28000 -32.7 -26.9 240 37 19 8.2 4.5 | -32.2 -26.0 230 38 19 8.7 4.8
27000 -30.3 -22.5 240 37 19 7.8 4.3 | -29.9 -21.8 230 37 19 7.4 4.1
26000 -27.9 -18.2 235 36 18 7.8 4.3 | -27.6 -17.7 230 35 18 7.4 4.1
25000 -25.6 -14.1 235 35 18 7.8 4.3 | -25.4 -13.7 230 34 17 7.4 4.1
24000 -23.2 -9.8 235 34 17 7.8 4.3 | -23.2 -9.8 230 32 16 7.4 4.1
23000 -20.9 -5.6 235 33 17 7.8 4.3 | -21.0 -5.8 235 29 15 7.4 4.1
22000 -18.5 -1.3 235 32 16 7.8 4.3 | -18.8 -1.8 235 27 14 7.5 4.1
21000 -16.1 3.0 235 30 15 8.1 4.4 | -16.5 2.3 235 24 13 8.2 4.5
20000 -13.7 7.3 235 28 14 8.1 4.5 | -14.0 6.8 230 22 11 8.2 4.5
19500 -12.5 9.5 235 27 14 8.1 4.5 | -12.8 9.0 230 21 11 8.3 4.5
19000 -11.3 11.7 235 26 13 8.1 4.5 | -11.6 11.1 225 20 10 8.4 4.6
18500 -10.1 13.8 235 25 13 8.1 4.4 | -10.3 13.5 225 20 10 8.7 4.8
18000 -8.9 16.0 235 23 12 8.1 4.4 | -9.0 15.8 220 20 10 8.7 4.8
17500 -7.7 18.1 235 22 11 8.2 4.5 | -7.7 18.1 220 20 10 8.9 4.9
17000 -6.5 20.3 235 21 11 8.3 4.5 | -6.4 20.5 215 21 11 8.9 4.9
16500 -5.3 22.5 235 20 10 8.5 4.7 | -4.4 24.1 210 21 11 9.1 5.0
16000 -3.3 26.1 230 18 10 9.0 5.0 | -3.1 26.4 210 21 11 9.1 5.0
15500 -2.0 28.4 225 18 9 8.9 4.9 | -1.7 28.9 205 20 11 9.2 5.1
15000 -0.6 30.9 220 17 9 8.8 4.8 | -0.3 31.5 205 20 10 9.3 5.1
14500 0.7 33.3 215 17 9 8.8 4.8 | 1.0 33.8 200 20 10 9.3 5.1
14000 2.0 35.6 210 16 8 8.9 4.9 | 2.4 36.3 200 19 10 9.3 5.1
13500 3.3 37.9 210 16 8 8.9 4.9 | 3.8 38.8 200 19 10 9.3 5.1
13000 4.6 40.3 205 15 8 8.6 4.7 | 5.2 41.4 200 18 10 9.7 5.3
12500 5.8 42.4 200 14 7 8.7 4.8 | 6.7 44.1 195 18 9 9.7 5.3
12000 7.1 44.8 200 13 7 8.4 4.6 | 8.1 46.6 195 17 9 9.2 5.0
11500 8.3 46.9 195 12 6 8.4 4.6 | 9.5 49.1 195 15 8 9.3 5.1
11000 9.5 49.1 195 11 6 8.1 4.5 | 10.8 51.4 195 14 7 8.5 4.6
10500 10.7 51.3 195 10 5 9.0 5.0 | 12.0 53.6 195 13 6 9.4 5.2
10250 11.5 52.7 190 9 5 11.5 6.3 | 12.8 55.0 195 12 6 11.3 6.2
10000 12.3 54.1 195 9 5 10.6 5.8 | 13.6 56.5 195 11 6 9.8 5.4
9750 13.0 55.4 195 9 5 9.5 5.2 | 14.3 57.7 195 10 5 8.7 4.8
9500 13.8 56.8 195 9 4 9.8 5.4 | 14.9 58.8 195 9 5 8.8 4.8
9250 14.5 58.1 195 8 4 9.7 5.3 | 15.6 60.1 195 8 4 9.4 5.2
9000 15.2 59.4 195 8 4 9.7 5.3 | 16.3 61.3 200 7 4 9.6 5.3
8750 15.9 60.6 195 8 4 9.9 5.4 | 17.0 62.6 200 6 3 9.2 5.0
8500 16.7 62.1 195 8 4 9.3 5.1 | 17.7 63.9 210 5 3 8.8 4.8
8250 17.4 63.3 195 8 4 11.5 6.3 | 18.4 65.1 215 4 2 10.6 5.8
8000 18.3 64.9 200 8 4 11.1 6.1 | 19.2 66.6 225 4 2 10.5 5.8
7750 19.0 66.2 200 7 4 8.8 4.8 | 19.9 67.8 235 4 2 8.7 4.8
7500 19.7 67.5 200 7 4 9.4 5.2 | 20.6 69.1 240 3 2 9.0 5.0
7250 20.4 68.7 200 7 4 10.4 5.7 | 21.3 70.3 250 3 2 10.5 5.7
7000 21.2 70.2 200 7 4 10.7 5.9 | 22.1 71.8 260 3 2 11.0 6.0
6750 22.0 71.6 205 7 4 9.2 5.1 | 22.8 73.0 265 3 2 9.0 5.0
6500 22.7 72.9 205 7 3 9.6 5.3 | 23.5 74.3 270 4 2 9.1 5.0
6250 23.4 74.1 205 6 3 10.9 6.0 | 24.2 75.6 275 4 2 10.4 5.7
6000 24.3 75.7 205 6 3 11.6 6.3 | 25.0 77.0 275 4 2 10.9 6.0
5750 25.1 77.2 210 6 3 10.2 5.6 | 25.8 78.4 280 4 2 9.6 5.3
5500 25.9 78.6 210 6 3 14.7 8.0 | 26.5 79.7 285 4 2 10.5 5.8
________________________________________________________________________________
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.
CIN (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: May 1st, 2013 15:31 UTC