170  
UXUS97 KPUB 241353  
SRGPUB  
 
SOARING FORECAST  
NATIONAL WEATHER SERVICE PUEBLO, COLORADO  
0753 MDT MONDAY, APRIL 24, 2017  
 
THIS FORECAST IS FOR MONDAY, APRIL 24, 2017:  
 
IF THE TRIGGER TEMPERATURE OF 55.0 F/12.8 C IS REACHED...THEN  
THERMAL SOARING INDEX....................... EXCELLENT  
MAXIMUM RATE OF LIFT........................ 1320 FT/MIN (6.7 M/S)  
MAXIMUM HEIGHT OF THERMALS.................. 21674 FT MSL (14060 FT AGL)  
 
FORECAST MAXIMUM TEMPERATURE................... 70.0 F/21.6 C  
TIME OF TRIGGER TEMPERATURE.................... 0830 MDT  
TIME OF OVERDEVELOPMENT........................ 1400 MDT  
MIDDLE/HIGH CLOUDS DURING SOARING WINDOW....... NONE  
SURFACE WINDS DURING SOARING WINDOW............ 20 MPH OR LESS  
HEIGHT OF THE -3 THERMAL INDEX................. 17852 FT MSL (10238 FT AGL)  
THERMAL SOARING OUTLOOK FOR TUESDAY 04/25...... GOOD  
 
WAVE SOARING INDEX............................. NOT AVAILABLE  
 
REMARKS...  
 
SUNRISE/SUNSET.................... 06:09:26 / 19:45:15 MDT  
TOTAL POSSIBLE SUNSHINE........... 13 HR 35 MIN 49 SEC (815 MIN 49 SEC)  
ALTITUDE OF SUN AT 12:57:20 MDT... 64.11 DEGREES  
 
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 04/24/2017 AT 0600 MDT  
 
FREEZING LEVEL.................. 11961 FT MSL (4347 FT AGL)  
CONVECTIVE CONDENSATION LEVEL... 17282 FT MSL (9668 FT AGL)  
LIFTED CONDENSATION LEVEL....... 18973 FT MSL (11359 FT AGL)  
LIFTED INDEX.................... -2.7  
K INDEX......................... -3.6  
 
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 -59.1 -74.4 260 26 13 -1.1 -0.6 M M M M M  
45000 -60.7 -77.3 250 34 17 -1.0 -0.5 M M M M M  
40000 -60.0 -76.0 250 31 16 0.6 0.3 M M M M M  
38000 -58.9 -74.0 255 30 15 3.2 1.8 M M M M M  
36000 -56.8 -70.2 265 29 15 3.2 1.8 M M M M M  
34000 -54.0 -65.2 270 30 15 9.2 5.0 M M M M M  
32000 -48.5 -55.3 275 31 16 9.2 5.0 M M M M M  
30000 -43.0 -45.4 275 32 16 9.2 5.1 25.0 77.0 3.0 M M  
29000 -40.2 -40.4 275 32 16 9.2 5.1 24.7 76.4 2.8 M M  
28000 -37.5 -35.5 275 31 16 9.2 5.1 24.5 76.2 2.7 M M  
27000 -34.7 -30.5 280 31 16 8.9 4.9 24.5 76.1 2.7 M M  
26000 -32.2 -26.0 280 29 15 8.3 4.5 23.8 74.9 2.2 M M  
25000 -29.7 -21.5 280 27 14 8.3 4.5 23.3 73.9 1.8 M M  
24000 -27.2 -17.0 280 25 13 8.3 4.6 22.9 73.1 1.4 M M  
23000 -24.9 -12.8 285 23 12 7.8 4.3 22.1 71.8 0.8 M M  
22000 -22.0 -7.6 285 21 11 7.8 4.3 21.3 70.3 0.1 M M  
21000 -19.7 -3.5 285 19 10 7.2 4.0 20.6 69.1 -0.5 1242 6.3  
20000 -17.5 0.5 285 19 10 7.2 4.0 19.7 67.4 -1.3 1148 5.8  
19500 -16.4 2.5 285 20 10 7.2 4.0 19.2 66.6 -1.7 1101 5.6  
19000 -15.3 4.5 285 20 10 7.2 4.0 18.8 65.9 -2.0 1054 5.4  
18500 -14.3 6.3 285 20 10 6.9 3.8 18.5 65.2 -2.4 1007 5.1  
18000 -13.3 8.1 280 20 10 6.7 3.7 17.9 64.3 -2.9 962 4.9  
17500 -12.3 9.9 275 20 10 6.7 3.7 17.4 63.3 -3.4 918 4.7  
17000 -11.2 11.8 270 20 10 7.5 4.1 17.0 62.5 -3.8 871 4.4  
16500 -10.1 13.8 270 20 10 7.4 4.1 16.6 61.8 -4.2 823 4.2  
16000 -9.0 15.8 270 20 10 7.9 4.3 16.2 61.2 -4.5 775 3.9  
15500 -7.8 18.0 270 21 11 8.1 4.4 15.9 60.7 -4.8 724 3.7  
15000 -6.6 20.1 270 22 11 8.0 4.4 15.7 60.2 -5.1 674 3.4  
14500 -5.4 22.3 270 22 11 7.9 4.3 15.4 59.7 -5.5 624 3.2  
14000 -4.3 24.3 270 23 12 7.9 4.3 15.1 59.1 -5.8 575 2.9  
13500 -3.1 26.4 270 23 12 8.1 4.5 14.8 58.7 -6.1 525 2.7  
13000 -1.9 28.6 275 24 12 5.2 2.9 14.6 58.3 -6.4 474 2.4  
12500 -1.2 29.8 275 23 12 7.6 4.2 13.8 56.9 -7.2 437 2.2  
12000 -0.2 31.6 275 22 11 6.6 3.6 13.4 56.1 -7.7 392 2.0  
11750 0.3 32.5 275 22 11 8.6 4.7 13.2 55.8 -7.9 369 1.9  
11500 1.0 33.8 275 21 11 8.7 4.8 13.2 55.7 -8.0 341 1.7  
11250 1.6 34.9 275 20 10 6.8 3.7 13.0 55.4 -8.2 318 1.6  
11000 2.1 35.8 275 20 10 7.4 4.1 12.8 55.0 -8.4 295 1.5  
10750 2.6 36.7 270 19 10 6.9 3.8 12.6 54.7 -8.7 271 1.4  
10500 3.1 37.6 270 19 10 6.6 3.6 12.3 54.2 -8.9 250 1.3  
10250 3.6 38.5 270 19 10 7.8 4.3 12.1 53.9 -9.2 227 1.2  
10000 4.2 39.6 270 18 9 8.2 4.5 12.0 53.6 -9.4 203 1.0  
9750 4.7 40.5 270 18 9 8.6 4.7 11.9 53.4 -9.6 178 0.9  
9500 5.4 41.7 270 17 9 9.5 5.2 11.9 53.3 -9.6 151 0.8  
9250 6.1 43.0 270 17 9 8.5 4.7 11.8 53.3 -9.7 123 0.6  
9000 6.7 44.1 275 16 8 8.0 4.4 11.7 53.0 -9.9 98 0.5  
8750 7.2 45.0 275 15 8 4.2 2.3 11.5 52.6 -10.1 75 0.4  
8500 7.3 45.1 275 13 7 0.5 0.3 10.8 51.5 -10.8 65 0.3  
8250 7.4 45.3 275 11 6 2.8 1.5 10.2 50.4 -11.5 55 0.3  
8000 7.5 45.5 280 10 5 -0.4 -0.2 9.7 49.4 -12.1 43 0.2  
7750 6.9 44.4 280 6 3 -17.5 -9.6 8.3 47.0 -13.4 54 0.3  
7500 M M M M M M M M M M M M  
7250 M M M M M M M M M M M M  
7000 M M M M M M M M M M M M  
6750 M M M M M M M M M M M M  
 
* * * * * * NUMERICAL WEATHER PREDICTION MODEL FORECAST DATA VALID * * * * * *  
 
04/24/2017 AT 0900 MDT | 04/24/2017 AT 1200 MDT  
|  
CAPE... 0.0 LI... +2.3 | CAPE... +29.4 LI... +0.7  
CINH... 0.0 K INDEX... -5.4 | CINH... 0.0 K INDEX... +6.5  
|  
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 -58.5 -73.3 260 23 12 -1.0 -0.5 | -58.7 -73.7 255 21 11 -1.9 -1.1  
45000 -59.9 -75.8 260 32 16 -0.9 -0.5 | -61.6 -78.9 260 30 16 -2.0 -1.1  
40000 -62.7 -80.9 265 31 16 -1.8 -1.0 | -62.6 -80.7 265 33 17 -0.6 -0.3  
38000 -61.8 -79.2 270 31 16 6.1 3.4 | -60.6 -77.1 270 33 17 6.3 3.5  
36000 -57.7 -71.9 270 30 16 6.1 3.3 | -56.8 -70.2 270 34 18 6.3 3.5  
34000 -53.6 -64.5 275 30 15 9.3 5.1 | -52.7 -62.9 270 35 18 8.7 4.8  
32000 -48.0 -54.4 270 29 15 9.3 5.1 | -47.4 -53.3 270 34 18 8.8 4.8  
30000 -42.5 -44.5 270 27 14 8.8 4.8 | -42.1 -43.8 270 33 17 9.1 5.0  
29000 -39.8 -39.6 270 27 14 8.9 4.9 | -39.3 -38.7 270 30 15 9.2 5.1  
28000 -37.1 -34.8 270 26 14 8.9 4.9 | -36.6 -33.9 265 28 14 9.2 5.1  
27000 -34.5 -30.1 275 26 13 8.5 4.7 | -33.8 -28.8 265 25 13 8.7 4.8  
26000 -32.1 -25.8 275 25 13 8.0 4.4 | -31.5 -24.7 265 26 13 7.9 4.4  
25000 -29.7 -21.5 275 24 12 8.0 4.4 | -29.1 -20.4 265 26 13 7.9 4.4  
24000 -27.3 -17.1 275 23 12 8.0 4.4 | -26.7 -16.1 265 27 14 8.0 4.4  
23000 -24.9 -12.8 275 22 11 8.2 4.5 | -24.5 -12.1 265 26 13 7.2 4.0  
22000 -22.4 -8.3 275 21 11 8.2 4.5 | -22.4 -8.3 265 25 13 7.2 4.0  
21000 -19.4 -2.9 275 20 10 7.4 4.0 | -19.7 -3.5 265 23 12 6.2 3.4  
20000 -17.2 1.0 275 20 10 7.4 4.0 | -17.8 -0.0 265 22 11 6.2 3.4  
19500 -16.1 3.0 275 19 10 7.4 4.0 | -16.9 1.6 265 22 11 6.2 3.4  
19000 -14.9 5.2 275 19 10 7.4 4.0 | -16.0 3.2 265 21 11 6.2 3.4  
18500 -13.9 7.0 275 19 10 6.6 3.6 | -15.0 5.0 265 21 11 5.7 3.1  
18000 -12.9 8.8 280 19 10 6.1 3.4 | -14.2 6.4 270 20 11 5.4 3.0  
17500 -12.0 10.4 280 20 10 6.1 3.4 | -13.4 7.9 270 20 10 5.4 3.0  
17000 -11.2 11.8 280 20 10 5.6 3.1 | -12.7 9.1 270 19 10 5.3 2.9  
16500 -10.3 13.5 280 20 10 5.7 3.1 | -11.9 10.6 270 17 9 5.3 2.9  
16000 -9.5 14.9 280 20 10 5.5 3.0 | -11.1 12.0 270 15 8 7.6 4.2  
15500 -8.7 16.3 280 20 10 5.4 3.0 | -9.9 14.2 270 13 6 8.2 4.5  
15000 -7.9 17.8 280 20 10 5.7 3.1 | -8.8 16.2 265 10 5 9.0 4.9  
14500 -7.0 19.4 280 19 10 6.1 3.3 | -7.3 18.9 265 9 5 9.7 5.3  
14000 -6.2 20.8 280 18 9 6.4 3.5 | -5.9 21.4 265 9 5 10.0 5.5  
13500 -5.1 22.8 285 17 9 8.1 4.4 | -4.3 24.3 265 8 4 11.2 6.1  
13000 -4.0 24.8 285 16 8 11.4 6.2 | -2.6 27.3 265 8 4 7.4 4.0  
12500 -2.6 27.3 285 15 8 6.3 3.5 | -1.5 29.3 265 8 4 10.6 5.8  
12000 -1.5 29.3 285 13 6 7.0 3.8 | -0.0 32.0 265 7 4 9.6 5.3  
11750 -1.0 30.2 285 12 6 9.1 5.0 | 0.7 33.3 265 7 4 10.7 5.9  
11500 -0.2 31.6 290 11 6 9.5 5.2 | 1.5 34.7 265 7 4 10.4 5.7  
11250 0.4 32.7 290 10 5 8.0 4.4 | 2.2 36.0 265 7 4 9.2 5.0  
11000 1.0 33.8 290 10 5 8.6 4.7 | 2.9 37.2 265 7 4 9.5 5.2  
10750 1.6 34.9 290 10 5 7.6 4.2 | 3.6 38.5 265 7 3 9.4 5.2  
10500 2.1 35.8 290 11 5 7.0 3.8 | 4.3 39.7 265 7 3 9.7 5.3  
10250 2.7 36.9 290 11 6 8.4 4.6 | 5.1 41.2 265 7 3 10.1 5.5  
10000 3.3 37.9 290 11 6 9.1 5.0 | 5.9 42.6 265 6 3 10.3 5.7  
9750 3.9 39.0 290 12 6 8.1 4.4 | 6.6 43.9 265 6 3 10.0 5.5  
9500 4.5 40.1 290 11 6 7.0 3.8 | 7.3 45.1 265 6 3 9.6 5.3  
9250 5.0 41.0 290 11 5 8.6 4.7 | 8.1 46.6 265 6 3 10.2 5.6  
9000 5.7 42.3 290 10 5 10.8 5.9 | 8.9 48.0 265 6 3 10.9 6.0  
8750 6.5 43.7 290 9 5 10.1 5.5 | 9.7 49.5 265 6 3 10.4 5.7  
8500 7.2 45.0 290 8 4 9.6 5.3 | 10.4 50.7 265 6 3 10.3 5.7  
8250 8.0 46.4 285 7 4 9.1 5.0 | 11.2 52.2 265 5 3 9.4 5.1  
8000 8.7 47.7 285 6 3 11.7 6.4 | 12.0 53.6 265 5 3 13.2 7.2  
7750 9.8 49.6 285 5 3 19.4 10.6 | 13.4 56.1 265 5 2 26.8 14.7  
7500 M M M M M M M | M M M M M M M  
7250 M M M M M M M | M M M M M M M  
7000 M M M M M M M | M M M M M M M  
6750 M M M M M M M | M M M M M M M  
 
04/24/2017 AT 1500 MDT | 04/24/2017 AT 1800 MDT  
|  
CAPE... +53.4 LI... -1.3 | CAPE... +2.7 LI... +0.1  
CINH... -0.2 K INDEX... +21.5 | CINH... -0.5 K INDEX... +20.6  
|  
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 -59.0 -74.2 265 21 11 -1.3 -0.7 | -58.7 -73.7 270 18 9 -0.2 -0.1  
45000 -61.0 -77.8 260 29 15 -1.4 -0.7 | -59.1 -74.4 265 24 13 -0.2 -0.1  
40000 -62.5 -80.5 275 43 22 -1.0 -0.5 | -62.0 -79.6 265 43 22 -2.0 -1.1  
38000 -60.5 -76.9 270 44 23 6.6 3.6 | -60.1 -76.2 265 45 23 7.6 4.2  
36000 -56.5 -69.7 270 43 22 6.6 3.6 | -55.5 -67.9 260 41 21 7.7 4.2  
34000 -52.2 -62.0 265 41 21 9.4 5.1 | -50.8 -59.4 255 39 20 8.1 4.4  
32000 -46.5 -51.7 260 33 17 9.4 5.2 | -46.0 -50.8 260 38 20 8.1 4.4  
30000 -41.0 -41.8 255 27 14 8.5 4.7 | -41.1 -42.0 265 37 19 8.4 4.6  
29000 -38.4 -37.1 260 27 14 8.6 4.7 | -38.6 -37.5 265 35 18 8.5 4.6  
28000 -35.8 -32.4 260 27 14 8.6 4.7 | -36.0 -32.8 265 33 17 8.5 4.7  
27000 -33.3 -27.9 260 27 14 8.2 4.5 | -33.5 -28.3 265 32 16 8.2 4.5  
26000 -31.0 -23.8 260 27 14 7.5 4.1 | -31.3 -24.3 265 29 15 7.2 3.9  
25000 -28.8 -19.8 260 27 14 7.5 4.1 | -29.1 -20.4 265 25 13 7.2 3.9  
24000 -26.6 -15.9 260 28 14 7.6 4.1 | -27.0 -16.6 265 22 11 7.2 3.9  
23000 -24.1 -11.4 260 27 14 6.6 3.6 | -24.3 -11.7 265 20 10 7.2 4.0  
22000 -22.1 -7.8 260 26 13 6.6 3.6 | -22.2 -8.0 265 19 10 7.3 4.0  
21000 -20.2 -4.4 260 24 13 6.0 3.3 | -20.1 -4.2 265 18 9 6.6 3.6  
20000 -18.5 -1.3 255 22 11 5.9 3.2 | -18.2 -0.8 265 19 10 6.4 3.5  
19500 -17.6 0.3 255 20 10 5.9 3.2 | -17.3 0.9 265 20 10 6.4 3.5  
19000 -16.8 1.8 255 19 10 5.9 3.2 | -16.3 2.7 265 20 10 6.4 3.5  
18500 -15.9 3.4 255 18 9 7.2 4.0 | -15.4 4.3 265 20 10 6.8 3.7  
18000 -14.7 5.5 255 16 8 8.1 4.5 | -14.3 6.3 260 21 11 7.2 4.0  
17500 -13.5 7.7 255 14 7 8.2 4.5 | -13.3 8.1 260 21 11 7.2 4.0  
17000 -12.3 9.9 255 13 6 8.0 4.4 | -12.2 10.0 255 21 11 7.6 4.2  
16500 -11.1 12.0 255 11 6 8.0 4.4 | -11.1 12.0 255 21 11 7.6 4.2  
16000 -9.9 14.2 255 10 5 9.0 4.9 | -9.9 14.2 255 20 10 8.1 4.5  
15500 -8.5 16.7 255 10 5 9.2 5.1 | -8.7 16.3 250 20 10 8.4 4.6  
15000 -7.1 19.2 255 9 5 9.5 5.2 | -7.4 18.7 250 19 10 8.6 4.7  
14500 -5.7 21.7 255 9 5 10.0 5.5 | -6.1 21.0 250 18 9 8.9 4.9  
14000 -4.2 24.4 255 9 5 10.2 5.6 | -4.8 23.4 250 16 8 8.8 4.9  
13500 -2.5 27.5 255 9 5 11.7 6.4 | -3.3 26.1 245 15 8 11.3 6.2  
13000 -0.7 30.7 255 9 5 6.5 3.6 | -1.6 29.1 245 13 7 7.6 4.2  
12500 0.3 32.5 255 9 4 11.1 6.1 | -0.7 30.7 245 12 6 9.2 5.0  
12000 1.8 35.2 255 9 4 9.6 5.3 | 0.7 33.3 245 11 6 9.3 5.1  
11750 2.5 36.5 255 9 4 10.9 6.0 | 1.5 34.7 245 11 6 11.2 6.1  
11500 3.4 38.1 255 8 4 10.6 5.8 | 2.3 36.1 245 11 6 10.5 5.8  
11250 4.1 39.4 255 8 4 8.9 4.9 | 3.0 37.4 245 11 6 8.2 4.5  
11000 4.8 40.6 255 8 4 9.5 5.2 | 3.6 38.5 245 11 6 8.9 4.9  
10750 5.5 41.9 255 8 4 9.0 4.9 | 4.3 39.7 245 11 5 8.3 4.5  
10500 6.1 43.0 255 8 4 9.2 5.1 | 4.9 40.8 245 11 5 8.2 4.5  
10250 6.9 44.4 255 8 4 10.4 5.7 | 5.6 42.1 245 10 5 9.5 5.2  
10000 7.7 45.9 255 8 4 10.9 6.0 | 6.3 43.3 245 10 5 10.2 5.6  
9750 8.5 47.3 255 8 4 10.1 5.5 | 7.1 44.8 245 10 5 9.7 5.3  
9500 9.2 48.6 255 8 4 9.0 4.9 | 7.8 46.0 245 10 5 8.9 4.9  
9250 9.9 49.8 255 8 4 9.7 5.3 | 8.4 47.1 245 10 5 9.4 5.2  
9000 10.6 51.1 255 8 4 10.8 5.9 | 9.2 48.6 245 10 5 10.7 5.9  
8750 11.4 52.5 255 7 4 10.4 5.7 | 10.0 50.0 245 9 5 9.8 5.4  
8500 12.2 54.0 255 7 4 10.0 5.5 | 10.7 51.3 245 9 5 8.6 4.7  
8250 12.9 55.2 255 7 4 10.0 5.5 | 11.3 52.3 245 9 5 8.7 4.8  
8000 13.7 56.7 255 7 4 10.1 5.5 | 12.0 53.6 245 8 4 9.0 5.0  
7750 14.5 58.1 255 6 3 14.5 8.0 | 12.7 54.9 245 8 4 10.7 5.9  
7500 M M M M M M M | M M M M M M M  
7250 M M M M M M M | M M M M M M M  
7000 M M M M M M M | M M M M M M M  
6750 M M M M M M M | M M M M M M M  
________________________________________________________________________________  
 
THIS PRODUCT IS ISSUED TWICE PER DAY, ONCE BY APPROXIMATELY 0630 MST/0730 MDT  
(1330 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 AIR FORCE ACADEMY  
IN COLORADO SPRINGS, COLORADO AT  
 
NORTH LATITUDE: 38 DEG 58 MIN 48.000 SEC  
WEST LONGITUDE: 104 DEG 49 MIN 12.000 SEC  
ELEVATION: 6572 FEET (2003 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  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab CO Page Main Text Page