Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
094
UXUS97 KBOU 121212
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0511 MST Wednesday, February 12, 2025
This forecast is for Wednesday, February 12, 2025:
If the trigger temperature of 16.2 F/-8.8 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 8408 ft MSL (3093 ft AGL)
Forecast maximum temperature................... 12.0 F/-11.6 C
Time of trigger temperature.................... None
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. None
Thermal soaring outlook for Thursday 02/13..... Poor
Wave Soaring Index............................. Good
Wave Soaring Index trend (to 1700 MST)......... Little change
Height of stable layer (12-18K ft MSL)......... 11958 ft MSL (6643 ft AGL)
Weak PVA/NVA (through 1700 MST)................ Weak NVA
Potential height of wave....................... 15157 ft MSL (9842 ft AGL)
Wave soaring outlook for Thursday 02/13........ Fair
Remarks... Very cold today and tonight
Sunrise/Sunset.................... 06:54:57 / 17:32:26 MST
Total possible sunshine........... 10 hr 37 min 29 sec (637 min 29 sec)
Altitude of sun at 12:13:41 MST... 36.72 degrees
Upper air data from numerical model forecast valid on 02/12/2025 at 0500 MST
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 14174 ft MSL (8859 ft AGL)
Lifted condensation level....... 8673 ft MSL (3358 ft AGL)
Lifted index.................... +16.6
K index......................... -2.8
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 -51.7 -61.1 265 42 22 1.7 0.9 M M M M M
45000 -49.0 -56.2 255 51 26 1.7 0.9 M M M M M
40000 -45.8 -50.4 255 53 27 2.3 1.2 M M M M M
38000 -44.4 -47.9 255 53 27 2.4 1.3 M M M M M
36000 -44.5 -48.1 250 54 28 -0.6 -0.3 M M M M M
34000 -44.8 -48.6 250 54 28 -0.6 -0.3 M M M M M
32000 -45.6 -50.1 250 53 27 -2.2 -1.2 M M M M M
30000 -47.0 -52.6 245 51 26 -2.2 -1.2 M M M M M
29000 -47.6 -53.7 245 50 26 -2.1 -1.1 M M M M M
28000 -47.9 -54.2 245 47 24 -0.7 -0.4 24.3 75.7 26.8 M M
27000 -48.2 -54.8 245 44 23 -0.7 -0.4 20.1 68.2 23.9 M M
26000 -48.4 -55.1 245 41 21 -0.5 -0.3 16.1 61.0 21.2 M M
25000 -47.5 -53.5 245 40 21 7.4 4.0 13.6 56.5 19.4 M M
24000 -45.2 -49.4 245 40 21 7.5 4.1 12.7 54.8 19.0 M M
23000 -43.0 -45.4 245 41 21 7.4 4.1 11.9 53.4 18.6 M M
22000 -40.9 -41.6 245 41 21 6.2 3.4 10.8 51.4 17.9 M M
21000 -39.1 -38.4 245 42 22 6.1 3.4 9.4 49.0 17.0 M M
20000 -37.2 -35.0 245 43 22 6.1 3.4 8.2 46.8 16.2 M M
19500 -36.3 -33.3 245 43 22 6.3 3.5 7.6 45.7 15.8 M M
19000 -35.4 -31.7 245 42 22 6.3 3.5 6.9 44.5 15.3 M M
18500 -34.4 -29.9 245 42 22 6.3 3.5 6.3 43.4 14.9 M M
18000 -33.5 -28.3 245 42 21 6.4 3.5 5.7 42.3 14.4 M M
17500 -32.6 -26.7 245 41 21 6.9 3.8 5.2 41.3 14.0 M M
17000 -30.5 -22.9 245 41 21 9.5 5.2 5.0 41.0 14.0 M M
16500 -29.1 -20.4 250 40 21 9.2 5.1 5.0 41.0 14.0 M M
16000 -27.8 -18.0 250 38 20 8.7 4.8 4.8 40.6 14.0 M M
15500 -26.5 -15.7 255 36 19 8.6 4.7 4.6 40.3 13.9 M M
15000 -25.3 -13.5 260 34 17 7.4 4.1 4.3 39.7 13.7 M M
14500 -24.2 -11.6 265 31 16 7.6 4.2 3.9 39.1 13.4 M M
14000 -23.2 -9.8 270 29 15 6.0 3.3 3.4 38.2 13.0 M M
13500 -22.3 -8.1 275 27 14 6.3 3.5 2.8 37.1 12.6 M M
13000 -21.5 -6.7 280 25 13 5.0 2.7 2.2 35.9 12.0 M M
12500 -20.7 -5.3 280 23 12 5.6 3.1 1.4 34.5 11.4 M M
12000 -20.3 -4.5 285 21 11 0.1 0.1 0.3 32.5 10.4 M M
11500 -20.2 -4.4 295 17 9 0.5 0.3 -1.2 29.8 9.1 M M
11000 -20.1 -4.2 300 15 8 0.4 0.2 -2.7 27.1 7.7 M M
10500 -20.1 -4.2 305 14 7 0.2 0.1 -4.2 24.5 6.4 M M
10250 -20.1 -4.2 310 13 7 -2.0 -1.1 -5.0 23.0 5.6 M M
10000 -20.3 -4.5 315 12 6 -3.2 -1.7 -6.0 21.1 4.7 M M
9750 -20.6 -5.1 320 12 6 -3.4 -1.9 -7.0 19.3 3.7 M M
9500 -20.8 -5.4 325 11 6 -1.9 -1.1 -8.1 17.5 2.8 M M
9250 -20.8 -5.4 330 10 5 0.9 0.5 -8.8 16.1 2.0 M M
9000 -20.7 -5.3 335 10 5 1.0 0.6 -9.5 14.8 1.4 M M
8750 -20.7 -5.3 345 10 5 1.4 0.7 -10.2 13.6 0.7 M M
8500 -20.5 -4.9 345 10 5 3.4 1.9 -10.8 12.6 0.2 M M
8250 -20.2 -4.4 355 11 5 4.9 2.7 -11.2 11.8 -0.2 228 1.2
8000 -19.8 -3.6 360 11 6 3.8 2.1 -11.6 11.1 -0.6 211 1.1
7750 -19.5 -3.1 005 12 6 6.7 3.7 -12.0 10.4 -1.0 194 1.0
7500 -18.9 -2.0 005 12 6 8.2 4.5 -12.1 10.2 -1.1 168 0.9
7250 -18.4 -1.1 005 12 6 5.9 3.2 -12.4 9.7 -1.4 146 0.7
7000 -17.9 -0.2 005 12 6 7.7 4.2 -12.6 9.3 -1.6 124 0.6
6750 -17.3 0.9 360 12 6 8.7 4.8 -12.7 9.1 -1.7 97 0.5
6500 -16.7 1.9 360 11 5 7.1 3.9 -12.8 8.9 -1.9 72 0.4
6250 -16.2 2.8 355 9 5 7.3 4.0 -13.1 8.5 -2.1 50 0.3
6000 -15.6 3.9 355 8 4 9.5 5.2 -13.2 8.3 -2.2 24 0.1
5750 -14.8 5.4 355 7 4 9.9 5.4 -13.1 8.4 -2.2 M M
5500 -14.1 6.6 360 6 3 8.6 4.7 -13.2 8.3 -2.3 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
02/12/2025 at 0800 MST | 02/12/2025 at 1100 MST
|
CAPE... +9.3 LI... +8.8 | CAPE... +10.3 LI... +8.4
CINH... 0.0 K Index... -13.5 | CINH... 0.0 K Index... -16.3
|
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 -52.1 -61.8 255 43 22 2.2 1.2 | -51.3 -60.3 255 42 21 2.2 1.2
45000 -48.6 -55.5 255 60 31 2.2 1.2 | -47.8 -54.0 260 50 26 2.2 1.2
40000 -45.1 -49.2 250 58 30 2.4 1.3 | -45.6 -50.1 255 57 29 1.2 0.7
38000 -43.7 -46.7 250 56 29 2.4 1.3 | -44.9 -48.8 255 60 31 1.2 0.7
36000 -43.8 -46.8 250 55 29 -1.0 -0.5 | -44.8 -48.6 255 60 31 -0.2 -0.1
34000 -44.4 -47.9 255 56 29 -1.0 -0.5 | -44.9 -48.8 255 59 31 -0.2 -0.1
32000 -45.6 -50.1 255 54 28 -3.5 -1.9 | -45.9 -50.6 260 57 29 -3.7 -2.0
30000 -47.7 -53.9 260 50 26 -3.5 -1.9 | -48.1 -54.6 260 53 27 -3.7 -2.0
29000 -48.8 -55.8 265 47 24 -3.5 -1.9 | -49.2 -56.6 260 50 26 -3.7 -2.0
28000 -48.9 -56.0 265 46 24 0.6 0.3 | -49.3 -56.7 265 47 24 0.5 0.3
27000 -48.7 -55.7 265 44 23 0.5 0.3 | -49.1 -56.4 265 44 23 0.5 0.3
26000 -48.6 -55.5 270 43 22 0.7 0.4 | -49.0 -56.2 265 41 21 0.7 0.4
25000 -47.7 -53.9 270 43 22 6.3 3.4 | -48.0 -54.4 265 39 20 7.2 3.9
24000 -45.8 -50.4 270 43 22 6.2 3.4 | -45.8 -50.4 265 39 20 7.2 3.9
23000 -43.9 -47.0 270 43 22 6.3 3.4 | -43.7 -46.7 270 39 20 7.2 3.9
22000 -41.8 -43.2 270 42 22 7.9 4.3 | -41.5 -42.7 270 40 20 7.1 3.9
21000 -39.4 -38.9 270 42 22 7.9 4.3 | -39.4 -38.9 275 40 21 7.1 3.9
20000 -37.1 -34.8 275 42 22 8.0 4.4 | -37.3 -35.1 275 41 21 7.1 3.9
19500 -36.0 -32.8 275 42 21 6.1 3.4 | -36.2 -33.2 275 41 21 6.9 3.8
19000 -35.1 -31.2 275 41 21 6.3 3.5 | -35.2 -31.4 275 40 20 7.0 3.8
18500 -34.1 -29.4 275 40 21 6.3 3.5 | -34.1 -29.4 275 39 20 7.0 3.8
18000 -33.2 -27.8 275 39 20 6.3 3.5 | -33.1 -27.6 275 38 19 6.9 3.8
17500 -32.2 -26.0 275 39 20 6.3 3.5 | -32.1 -25.8 275 37 19 6.9 3.8
17000 -30.9 -23.6 275 38 20 6.1 3.3 | -30.6 -23.1 275 35 18 6.2 3.4
16500 -30.0 -22.0 275 38 19 5.8 3.2 | -29.7 -21.5 275 34 18 5.7 3.1
16000 -29.2 -20.6 270 37 19 5.2 2.9 | -29.0 -20.2 275 34 18 4.5 2.5
15500 -28.4 -19.1 270 37 19 5.3 2.9 | -28.3 -18.9 280 34 18 4.6 2.5
15000 -27.6 -17.7 265 36 19 5.3 2.9 | -27.6 -17.7 280 34 17 4.8 2.6
14500 -26.8 -16.2 265 35 18 5.3 2.9 | -26.9 -16.4 280 32 17 4.7 2.6
14000 -26.0 -14.8 265 33 17 6.1 3.4 | -26.2 -15.2 280 32 17 5.3 2.9
13500 -25.1 -13.2 265 31 16 6.1 3.4 | -25.4 -13.7 280 34 18 5.3 2.9
13000 -24.2 -11.6 270 28 15 5.6 3.0 | -24.6 -12.3 275 34 18 5.6 3.1
12500 -23.4 -10.1 270 25 13 6.0 3.3 | -23.8 -10.8 275 31 16 5.5 3.0
12000 -22.8 -9.0 280 23 12 1.4 0.8 | -22.9 -9.2 275 29 15 6.5 3.6
11500 -22.6 -8.7 285 20 10 1.9 1.0 | -21.9 -7.4 285 27 14 6.7 3.7
11000 -22.5 -8.5 290 17 9 -0.8 -0.4 | -21.5 -6.7 285 23 12 -1.0 -0.6
10500 -22.6 -8.7 300 14 7 -0.6 -0.3 | -21.6 -6.9 290 18 9 -0.2 -0.1
10250 -22.6 -8.7 305 12 6 -0.8 -0.4 | -21.6 -6.9 295 16 8 0.3 0.1
10000 -22.7 -8.9 310 11 6 -0.7 -0.4 | -21.6 -6.9 295 14 7 0.7 0.4
9750 -22.8 -9.0 315 11 5 -1.6 -0.9 | -21.5 -6.7 300 12 6 -0.4 -0.2
9500 -22.8 -9.0 325 9 5 1.0 0.5 | -21.6 -6.9 305 10 5 -0.8 -0.4
9250 -22.6 -8.7 335 9 5 4.4 2.4 | -21.6 -6.9 310 9 4 0.1 0.1
9000 -22.3 -8.1 345 9 5 4.0 2.2 | -21.6 -6.9 315 7 4 0.2 0.1
8750 -22.0 -7.6 350 9 5 4.3 2.4 | -21.6 -6.9 325 6 3 -0.2 -0.1
8500 -21.7 -7.1 360 10 5 3.5 1.9 | -21.6 -6.9 335 5 3 2.2 1.2
8250 -21.4 -6.5 005 11 5 2.9 1.6 | -21.3 -6.3 355 5 3 4.6 2.5
8000 -21.2 -6.2 010 11 6 2.6 1.4 | -21.0 -5.8 015 5 3 3.4 1.9
7750 -21.0 -5.8 015 12 6 6.6 3.6 | -20.6 -5.1 030 6 3 8.0 4.4
7500 -20.3 -4.5 015 12 6 8.8 4.8 | -19.9 -3.8 035 6 3 10.4 5.7
7250 -19.8 -3.6 015 12 6 5.9 3.3 | -19.2 -2.6 035 5 3 7.8 4.3
7000 -19.3 -2.7 015 12 6 9.3 5.1 | -18.6 -1.5 035 5 3 10.5 5.8
6750 -18.4 -1.1 015 11 6 11.3 6.2 | -17.7 0.1 035 5 3 11.6 6.4
6500 -17.7 0.1 015 10 5 8.5 4.7 | -16.9 1.6 035 5 3 8.8 4.8
6250 -17.1 1.2 010 10 5 9.2 5.1 | -16.3 2.7 035 5 3 9.5 5.2
6000 -16.3 2.7 010 9 5 11.9 6.5 | -15.5 4.1 035 5 3 12.2 6.7
5750 -15.4 4.3 010 8 4 10.5 5.8 | -14.6 5.7 035 5 3 10.6 5.8
5500 -14.7 5.5 005 7 4 9.5 5.2 | -13.8 7.2 035 5 2 12.6 6.9
02/12/2025 at 1400 MST | 02/12/2025 at 1700 MST
|
CAPE... +5.6 LI... +6.7 | CAPE... +1.7 LI... +4.8
CINH... 0.0 K Index... -4.5 | CINH... 0.0 K Index... +2.1
|
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 -59.8 260 47 24 2.7 1.5 | -51.3 -60.3 270 50 26 2.2 1.2
45000 -46.7 -52.1 260 52 27 2.7 1.5 | -47.9 -54.2 270 54 28 2.2 1.2
40000 -45.4 -49.7 265 60 31 0.4 0.2 | -46.4 -51.5 270 57 29 0.7 0.4
38000 -45.2 -49.4 265 63 33 0.3 0.2 | -45.9 -50.6 275 58 30 0.7 0.4
36000 -45.7 -50.3 265 62 32 -1.1 -0.6 | -46.2 -51.2 275 56 29 -0.8 -0.5
34000 -46.4 -51.5 265 59 30 -1.1 -0.6 | -46.7 -52.1 275 54 28 -0.8 -0.5
32000 -47.2 -53.0 260 57 29 -1.9 -1.1 | -47.2 -53.0 275 53 27 -0.8 -0.5
30000 -48.5 -55.3 265 57 29 -1.9 -1.1 | -47.8 -54.0 275 55 28 -0.8 -0.5
29000 -49.1 -56.4 265 57 29 -1.9 -1.0 | -48.0 -54.4 275 55 28 -0.8 -0.4
28000 -49.2 -56.6 265 56 29 -0.1 -0.1 | -48.2 -54.8 275 55 28 -0.4 -0.2
27000 -49.3 -56.7 265 55 29 -0.2 -0.1 | -48.3 -54.9 275 55 28 -0.4 -0.2
26000 -49.3 -56.7 270 55 28 0.0 0.0 | -48.4 -55.1 275 54 28 -0.3 -0.1
25000 -48.5 -55.3 270 54 28 6.1 3.3 | -47.9 -54.2 275 54 28 4.1 2.3
24000 -46.7 -52.1 270 52 27 6.1 3.3 | -46.7 -52.1 275 54 28 4.2 2.3
23000 -44.9 -48.8 270 50 26 6.2 3.4 | -45.4 -49.7 275 54 28 4.3 2.3
22000 -42.8 -45.0 270 49 25 7.7 4.2 | -43.6 -46.5 275 52 27 7.6 4.2
21000 -40.5 -40.9 270 48 25 7.7 4.2 | -41.3 -42.3 270 49 25 7.7 4.2
20000 -38.2 -36.8 270 47 24 7.8 4.3 | -39.0 -38.2 270 46 23 7.7 4.2
19500 -36.9 -34.4 270 47 24 8.5 4.7 | -37.8 -36.0 270 44 22 7.9 4.3
19000 -35.7 -32.3 270 46 24 8.5 4.6 | -36.7 -34.1 265 41 21 7.9 4.3
18500 -34.4 -29.9 270 46 24 8.5 4.6 | -35.5 -31.9 265 39 20 7.9 4.3
18000 -33.1 -27.6 270 46 23 8.4 4.6 | -34.3 -29.7 260 38 19 7.8 4.3
17500 -31.9 -25.4 270 45 23 8.0 4.4 | -33.1 -27.6 260 36 18 7.3 4.0
17000 -30.8 -23.4 265 44 23 6.2 3.4 | -32.2 -26.0 260 36 19 5.7 3.1
16500 -29.9 -21.8 265 43 22 6.6 3.6 | -31.4 -24.5 260 38 19 5.8 3.2
16000 -28.8 -19.8 265 41 21 3.9 2.1 | -30.5 -22.9 265 39 20 5.6 3.1
15500 -28.3 -18.9 265 39 20 4.1 2.2 | -29.3 -20.7 265 42 21 5.9 3.3
15000 -27.6 -17.7 265 38 20 5.4 3.0 | -28.3 -18.9 265 40 21 6.8 3.7
14500 -26.8 -16.2 260 37 19 5.4 3.0 | -27.3 -17.1 265 38 20 7.0 3.8
14000 -25.8 -14.4 265 35 18 7.6 4.2 | -26.1 -15.0 265 36 18 9.0 4.9
13500 -24.7 -12.5 265 33 17 7.4 4.1 | -24.8 -12.6 270 34 17 8.8 4.8
13000 -23.7 -10.7 265 30 15 6.7 3.7 | -23.5 -10.3 270 32 16 8.0 4.4
12500 -22.7 -8.9 265 25 13 6.8 3.7 | -22.3 -8.1 275 30 15 8.0 4.4
12000 -21.6 -6.9 270 23 12 6.9 3.8 | -21.3 -6.3 275 28 14 6.5 3.5
11500 -20.6 -5.1 275 24 12 6.9 3.8 | -20.3 -4.5 275 25 13 6.1 3.3
11000 -20.1 -4.2 275 21 11 1.0 0.5 | -19.7 -3.5 275 22 11 2.5 1.4
10500 -19.9 -3.8 270 15 8 1.7 0.9 | -19.3 -2.7 275 18 9 2.4 1.3
10250 -19.7 -3.5 270 14 7 2.0 1.1 | -19.2 -2.6 270 17 9 1.7 0.9
10000 -19.5 -3.1 275 13 6 3.5 1.9 | -19.0 -2.2 270 15 8 1.6 0.9
9750 -19.3 -2.7 275 12 6 -1.2 -0.6 | -18.9 -2.0 265 13 7 1.6 0.9
9500 -19.6 -3.3 275 9 5 -2.7 -1.5 | -18.8 -1.8 260 11 6 0.7 0.4
9250 -19.6 -3.3 280 7 4 1.1 0.6 | -18.8 -1.8 255 9 5 0.0 0.0
9000 -19.6 -3.3 280 5 3 1.3 0.7 | -18.8 -1.8 250 7 4 0.6 0.3
8750 -19.5 -3.1 285 3 2 -1.2 -0.7 | -18.8 -1.8 235 5 3 -1.1 -0.6
8500 -19.6 -3.3 285 2 1 0.6 0.3 | -18.8 -1.8 220 4 2 2.3 1.2
8250 -19.3 -2.7 345 1 1 5.0 2.7 | -18.4 -1.1 190 3 1 6.2 3.4
8000 -19.1 -2.4 055 2 1 2.8 1.5 | -18.0 -0.4 140 2 1 5.6 3.0
7750 -18.8 -1.8 070 4 2 9.1 5.0 | -17.5 0.5 110 4 2 9.4 5.1
7500 -17.8 -0.0 065 4 2 11.6 6.4 | -16.7 1.9 105 4 2 10.2 5.6
7250 -17.2 1.0 065 4 2 7.5 4.1 | -16.0 3.2 100 4 2 8.5 4.6
7000 -16.5 2.3 065 4 2 10.4 5.7 | -15.4 4.3 095 4 2 9.9 5.5
6750 -15.7 3.7 065 4 2 11.3 6.2 | -14.6 5.7 095 4 2 10.5 5.8
6500 -14.9 5.2 065 4 2 9.4 5.2 | -13.8 7.2 090 4 2 9.5 5.2
6250 -14.2 6.4 065 4 2 9.8 5.4 | -13.1 8.4 090 4 2 9.7 5.3
6000 -13.4 7.9 060 4 2 12.0 6.6 | -12.4 9.7 090 4 2 10.5 5.7
5750 -12.5 9.5 060 4 2 10.9 6.0 | -11.6 11.1 085 4 2 9.7 5.3
5500 -11.7 10.9 060 4 2 12.2 6.7 | -10.9 12.4 085 3 2 9.3 5.1
________________________________________________________________________________
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.
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