477  
UXUS97 KPUB 221300  
SRGPUB  
 
SOARING FORECAST  
NATIONAL WEATHER SERVICE PUEBLO, COLORADO  
0659 MDT FRIDAY, SEPTEMBER 22, 2017  
 
THIS FORECAST IS FOR FRIDAY, SEPTEMBER 22, 2017:  
 
IF THE TRIGGER TEMPERATURE OF 66.4 F/19.1 C IS REACHED...THEN  
THERMAL SOARING INDEX....................... GOOD  
MAXIMUM RATE OF LIFT........................ 779 FT/MIN (4.0 M/S)  
MAXIMUM HEIGHT OF THERMALS.................. 16853 FT MSL (9252 FT AGL)  
 
FORECAST MAXIMUM TEMPERATURE................... 79.0 F/26.6 C  
TIME OF TRIGGER TEMPERATURE.................... 0930 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................. 14266 FT MSL (6665 FT AGL)  
THERMAL SOARING OUTLOOK FOR SATURDAY 09/23..... FAIR  
 
WAVE SOARING INDEX............................. NOT AVAILABLE  
 
REMARKS...  
 
SUNRISE/SUNSET.................... 06:47:28 / 18:56:15 MDT  
TOTAL POSSIBLE SUNSHINE........... 12 HR 8 MIN 47 SEC (728 MIN 47 SEC)  
ALTITUDE OF SUN AT 12:51:52 MDT... 51.01 DEGREES  
 
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 09/22/2017 AT 0600 MDT  
 
FREEZING LEVEL.................. 15911 FT MSL (8310 FT AGL)  
CONVECTIVE CONDENSATION LEVEL... 18970 FT MSL (11369 FT AGL)  
LIFTED CONDENSATION LEVEL....... 18489 FT MSL (10888 FT AGL)  
LIFTED INDEX.................... -1.1  
K INDEX......................... -8.0  
 
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 -66.4 -87.5 225 34 17 2.7 1.5 M M M M M  
45000 -61.6 -78.9 225 39 20 5.0 2.7 M M M M M  
40000 -54.1 -65.4 235 38 20 6.0 3.3 M M M M M  
38000 -50.3 -58.5 235 38 20 6.3 3.5 M M M M M  
36000 -46.0 -50.8 230 38 20 6.4 3.5 M M M M M  
34000 -41.6 -42.9 230 36 19 7.7 4.2 M M M M M  
32000 -36.9 -34.4 230 34 18 7.7 4.2 M M M M M  
30000 -31.9 -25.4 220 28 14 8.6 4.7 36.6 97.9 8.2 M M  
29000 -29.3 -20.7 215 24 12 8.6 4.7 36.2 97.2 8.0 M M  
28000 -26.8 -16.2 205 20 11 8.9 4.9 35.9 96.6 7.8 M M  
27000 -24.7 -12.5 205 21 11 6.3 3.5 34.8 94.7 7.0 M M  
26000 -22.8 -9.0 205 23 12 6.4 3.5 33.5 92.3 6.0 M M  
25000 -20.9 -5.6 205 25 13 6.4 3.5 32.3 90.2 5.1 M M  
24000 -18.8 -1.8 205 26 14 7.9 4.3 31.4 88.5 4.3 M M  
23000 -16.4 2.5 205 26 13 7.9 4.3 30.7 87.2 3.8 M M  
22000 -14.1 6.6 205 26 13 7.9 4.3 30.1 86.1 3.3 M M  
21000 -11.1 12.0 205 25 13 7.8 4.3 29.2 84.6 2.6 M M  
20000 -8.8 16.2 205 24 12 7.8 4.3 28.5 83.4 2.1 M M  
19500 -7.6 18.3 205 24 12 7.8 4.3 28.2 82.8 1.8 M M  
19000 -6.4 20.5 205 23 12 7.6 4.2 28.0 82.3 1.6 M M  
18500 -5.3 22.5 205 23 12 7.5 4.1 27.6 81.6 1.2 M M  
18000 -4.2 24.4 205 22 12 7.5 4.1 27.2 80.9 0.9 M M  
17500 -3.1 26.4 205 22 11 6.8 3.7 26.7 80.1 0.5 M M  
17000 -2.1 28.2 205 21 11 6.8 3.8 26.3 79.3 0.1 M M  
16500 -1.1 30.0 205 21 11 6.7 3.7 25.8 78.4 -0.3 742 3.8  
16000 -0.1 31.8 205 20 11 6.6 3.6 25.3 77.5 -0.9 698 3.5  
15500 0.9 33.6 205 20 10 6.4 3.5 24.7 76.5 -1.4 655 3.3  
15000 1.7 35.1 210 20 10 5.3 2.9 24.1 75.4 -2.0 615 3.1  
14500 2.5 36.5 210 20 10 5.5 3.0 23.4 74.1 -2.7 577 2.9  
14000 3.2 37.8 215 20 10 5.3 2.9 22.7 72.8 -3.4 539 2.7  
13500 4.0 39.2 220 20 11 5.3 2.9 22.0 71.6 -4.2 503 2.6  
13000 4.8 40.6 220 21 11 7.5 4.1 21.4 70.6 -4.8 463 2.4  
12500 5.6 42.1 225 21 11 5.1 2.8 20.9 69.6 -5.5 424 2.2  
12000 6.3 43.3 225 21 11 6.6 3.6 20.2 68.4 -6.3 388 2.0  
11750 6.8 44.2 225 21 11 7.9 4.4 20.0 68.1 -6.5 366 1.9  
11500 7.4 45.3 225 20 10 8.2 4.5 19.9 67.8 -6.7 342 1.7  
11250 7.9 46.2 225 20 10 8.8 4.8 19.8 67.6 -6.9 317 1.6  
11000 8.5 47.3 230 19 10 7.8 4.3 19.7 67.5 -7.1 292 1.5  
10750 9.0 48.2 230 18 9 6.9 3.8 19.5 67.1 -7.3 269 1.4  
10500 9.6 49.3 230 18 9 7.2 4.0 19.3 66.7 -7.5 246 1.3  
10250 10.1 50.2 230 17 9 7.9 4.3 19.1 66.4 -7.7 222 1.1  
10000 10.7 51.3 235 17 9 7.0 3.9 19.0 66.2 -7.9 198 1.0  
9750 11.1 52.0 235 16 8 5.8 3.2 18.7 65.6 -8.2 177 0.9  
9500 11.6 52.9 240 16 8 6.3 3.5 18.4 65.1 -8.5 156 0.8  
9250 12.0 53.6 240 15 8 5.2 2.8 18.1 64.6 -8.8 135 0.7  
9000 12.4 54.3 245 14 7 5.2 2.9 17.7 63.9 -9.1 115 0.6  
8750 12.9 55.2 245 12 6 6.0 3.3 17.4 63.4 -9.4 94 0.5  
8500 13.4 56.1 245 11 6 6.7 3.7 17.2 62.9 -9.7 73 0.4  
8250 13.8 56.8 245 10 5 2.9 1.6 16.9 62.4 -10.0 51 0.3  
8000 13.6 56.5 240 9 4 -10.4 -5.7 15.9 60.6 -11.0 50 0.3  
7750 12.4 54.3 240 6 3 -20.5 -11.3 13.9 57.1 -12.9 79 0.4  
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 * * * * * *  
 
09/22/2017 AT 0900 MDT | 09/22/2017 AT 1200 MDT  
|  
CAPE... 0.0 LI... +3.8 | CAPE... +7.0 LI... +2.2  
CINH... 0.0 K INDEX... -9.6 | CINH... -78.5 K INDEX... -0.7  
|  
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 -64.9 -84.8 220 31 16 2.3 1.3 | -65.7 -86.3 215 30 16 3.0 1.7  
45000 -60.8 -77.4 225 41 21 4.5 2.5 | -60.8 -77.4 225 46 24 4.1 2.3  
40000 -53.9 -65.0 230 45 23 5.5 3.0 | -54.6 -66.3 225 51 26 5.8 3.2  
38000 -49.8 -57.6 230 45 23 6.1 3.4 | -49.9 -57.8 225 50 26 6.9 3.8  
36000 -46.1 -51.0 225 44 23 6.2 3.4 | -45.8 -50.4 220 49 25 6.9 3.8  
34000 -41.7 -43.1 225 42 22 7.7 4.2 | -41.4 -42.5 220 46 24 7.5 4.1  
32000 -37.1 -34.8 225 39 20 7.7 4.2 | -36.8 -34.2 215 44 23 7.6 4.2  
30000 -32.3 -26.1 215 33 17 8.1 4.5 | -32.1 -25.8 215 40 21 8.1 4.4  
29000 -29.9 -21.8 210 30 15 8.1 4.5 | -29.6 -21.3 215 38 19 8.1 4.4  
28000 -27.5 -17.5 205 26 14 8.2 4.5 | -27.2 -17.0 210 36 18 8.2 4.5  
27000 -25.3 -13.5 205 26 14 6.7 3.7 | -25.0 -13.0 210 34 18 7.0 3.9  
26000 -23.3 -9.9 205 28 14 6.7 3.7 | -22.9 -9.2 210 34 17 7.0 3.9  
25000 -21.3 -6.3 205 29 15 6.8 3.7 | -20.8 -5.4 210 33 17 7.0 3.9  
24000 -19.2 -2.6 205 30 15 7.8 4.3 | -18.8 -1.8 210 32 17 6.1 3.4  
23000 -16.9 1.6 205 29 15 7.8 4.3 | -16.9 1.6 210 31 16 6.2 3.4  
22000 -13.9 7.0 200 28 14 7.7 4.2 | -14.7 5.5 205 29 15 6.2 3.4  
21000 -11.5 11.3 200 27 14 8.0 4.4 | -12.3 9.9 205 28 14 8.6 4.7  
20000 -9.1 15.6 200 27 14 8.0 4.4 | -9.7 14.5 205 26 14 8.6 4.7  
19500 -7.9 17.8 200 26 14 8.0 4.4 | -8.4 16.9 205 26 13 8.5 4.7  
19000 -6.7 19.9 200 26 13 7.5 4.1 | -7.1 19.2 205 25 13 8.1 4.4  
18500 -5.6 21.9 205 25 13 7.2 4.0 | -5.9 21.4 210 26 13 7.8 4.3  
18000 -4.5 23.9 205 25 13 7.3 4.0 | -4.8 23.4 210 26 13 8.1 4.4  
17500 -3.5 25.7 205 24 13 6.4 3.5 | -3.8 25.2 215 26 14 4.6 2.5  
17000 -2.6 27.3 205 24 12 6.5 3.5 | -3.1 26.4 215 26 14 4.9 2.7  
16500 -1.6 29.1 210 24 12 5.7 3.1 | -2.4 27.7 220 26 13 4.1 2.3  
16000 -0.9 30.4 210 23 12 5.1 2.8 | -1.9 28.6 220 26 13 3.6 2.0  
15500 -0.1 31.8 215 23 12 5.1 2.8 | -1.4 29.5 225 26 13 3.8 2.1  
15000 0.5 32.9 215 23 12 4.3 2.4 | -0.9 30.4 230 25 13 4.7 2.6  
14500 1.1 34.0 220 22 12 4.4 2.4 | -0.2 31.6 230 25 13 4.7 2.6  
14000 1.8 35.2 225 22 12 4.9 2.7 | 0.5 32.9 230 25 13 6.2 3.4  
13500 2.4 36.3 230 23 12 4.8 2.7 | 1.3 34.3 230 24 12 6.0 3.3  
13000 3.2 37.8 230 23 12 7.6 4.2 | 2.3 36.1 230 23 12 8.7 4.8  
12500 4.2 39.6 230 22 11 6.1 3.4 | 3.3 37.9 230 21 11 6.6 3.6  
12000 5.0 41.0 235 20 10 7.1 3.9 | 4.3 39.7 230 18 9 7.4 4.0  
11750 5.6 42.1 230 19 10 7.7 4.2 | 4.8 40.6 225 17 9 8.0 4.4  
11500 6.1 43.0 230 17 9 7.3 4.0 | 5.5 41.9 225 16 8 9.1 5.0  
11250 6.6 43.9 225 16 8 7.3 4.0 | 6.1 43.0 225 15 8 9.8 5.4  
11000 7.1 44.8 225 14 7 7.1 3.9 | 6.8 44.2 220 14 7 8.5 4.6  
10750 7.6 45.7 225 13 7 6.9 3.8 | 7.4 45.3 215 13 7 7.1 3.9  
10500 8.0 46.4 220 13 7 7.0 3.8 | 7.9 46.2 210 12 6 8.7 4.8  
10250 8.5 47.3 225 13 6 7.1 3.9 | 8.7 47.7 210 12 6 12.3 6.7  
10000 9.0 48.2 225 12 6 6.1 3.4 | 9.6 49.3 205 11 6 10.8 5.9  
9750 9.4 48.9 225 12 6 5.4 2.9 | 10.3 50.5 200 11 6 8.6 4.7  
9500 9.8 49.6 230 12 6 5.2 2.8 | 11.0 51.8 200 11 5 8.5 4.7  
9250 10.2 50.4 230 12 6 6.7 3.7 | 11.6 52.9 195 10 5 10.9 6.0  
9000 10.8 51.4 230 10 5 8.3 4.6 | 12.6 54.7 190 10 5 11.6 6.4  
8750 11.4 52.5 230 9 5 7.7 4.2 | 13.3 55.9 190 10 5 9.7 5.3  
8500 12.0 53.6 225 8 4 8.0 4.4 | 14.0 57.2 190 10 5 9.8 5.4  
8250 12.6 54.7 220 7 4 7.4 4.1 | 14.8 58.6 190 10 5 11.4 6.2  
8000 13.2 55.8 215 6 3 10.7 5.9 | 15.9 60.6 190 10 5 18.8 10.3  
7750 14.3 57.7 205 5 3 17.6 9.6 | 17.6 63.7 185 9 5 25.7 14.1  
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  
 
09/22/2017 AT 1500 MDT | 09/22/2017 AT 1800 MDT  
|  
CAPE... +83.4 LI... 0.0 | CAPE... +65.4 LI... -1.4  
CINH... -2.9 K INDEX... +7.7 | CINH... -12.3 K INDEX... +24.1  
|  
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 -65.7 -86.3 225 35 18 3.6 2.0 | -64.5 -84.1 225 32 16 3.6 2.0  
45000 -60.3 -76.5 225 50 25 3.7 2.1 | -59.3 -74.7 230 46 24 2.9 1.6  
40000 -54.7 -66.5 225 56 29 5.2 2.9 | -55.0 -67.0 225 49 25 4.1 2.3  
38000 -50.2 -58.4 220 54 28 6.7 3.7 | -50.8 -59.4 225 49 25 6.2 3.4  
36000 -46.2 -51.2 220 52 27 6.7 3.7 | -47.1 -52.8 220 49 25 6.2 3.4  
34000 -41.8 -43.2 220 49 25 7.6 4.2 | -42.7 -44.9 220 48 24 7.9 4.3  
32000 -37.2 -35.0 215 46 24 7.6 4.2 | -38.0 -36.4 220 45 23 7.9 4.3  
30000 -32.6 -26.7 215 43 22 7.7 4.2 | -33.1 -27.6 220 42 22 8.3 4.5  
29000 -30.3 -22.5 215 40 21 7.7 4.2 | -30.6 -23.1 220 41 21 8.3 4.5  
28000 -28.0 -18.4 215 38 20 7.7 4.2 | -28.1 -18.6 215 40 21 8.3 4.6  
27000 -25.8 -14.4 215 37 19 7.4 4.0 | -25.9 -14.6 215 39 20 7.1 3.9  
26000 -23.6 -10.5 215 36 19 7.4 4.0 | -23.8 -10.8 215 38 20 7.1 3.9  
25000 -21.4 -6.5 215 35 18 7.3 4.0 | -21.6 -6.9 215 37 19 7.1 3.9  
24000 -19.3 -2.7 215 34 18 6.0 3.3 | -19.7 -3.5 215 36 19 5.0 2.8  
23000 -17.5 0.5 215 32 17 6.2 3.4 | -18.2 -0.8 215 35 18 5.2 2.8  
22000 -15.3 4.5 210 30 16 6.3 3.4 | -16.3 2.7 215 34 17 5.2 2.8  
21000 -13.1 8.4 210 30 15 7.5 4.1 | -14.5 5.9 215 32 17 6.7 3.7  
20000 -10.8 12.6 210 29 15 7.5 4.1 | -12.5 9.5 215 31 16 6.8 3.7  
19500 -9.7 14.5 210 29 15 7.5 4.1 | -11.5 11.3 215 31 16 6.8 3.8  
19000 -8.6 16.5 215 29 15 6.9 3.8 | -10.5 13.1 215 30 15 7.3 4.0  
18500 -7.6 18.3 215 28 14 6.4 3.5 | -9.4 15.1 215 29 15 7.8 4.3  
18000 -6.7 19.9 215 27 14 6.5 3.6 | -8.3 17.1 210 28 14 7.9 4.3  
17500 -5.9 21.4 215 27 14 4.7 2.6 | -7.2 19.0 210 26 14 7.7 4.2  
17000 -5.2 22.6 220 27 14 5.0 2.8 | -6.1 21.0 205 25 13 7.8 4.3  
16500 -4.5 23.9 220 27 14 5.7 3.1 | -5.0 23.0 205 23 12 8.4 4.6  
16000 -3.7 25.3 220 25 13 6.2 3.4 | -3.7 25.3 200 22 11 8.9 4.9  
15500 -2.9 26.8 215 24 12 6.6 3.6 | -2.4 27.7 200 21 11 9.0 4.9  
15000 -1.9 28.6 215 22 11 8.3 4.5 | -1.1 30.0 195 21 11 9.1 5.0  
14500 -0.7 30.7 210 20 10 8.2 4.5 | 0.3 32.5 195 20 10 9.1 5.0  
14000 0.5 32.9 210 19 10 8.8 4.8 | 1.7 35.1 190 20 10 9.5 5.2  
13500 1.8 35.2 205 18 9 8.6 4.7 | 3.1 37.6 190 20 10 9.0 5.0  
13000 3.2 37.8 205 17 9 10.6 5.8 | 4.7 40.5 190 19 10 12.0 6.6  
12500 4.5 40.1 205 16 8 8.5 4.7 | 6.1 43.0 190 19 10 7.6 4.1  
12000 5.8 42.4 200 16 8 8.8 4.8 | 7.3 45.1 190 19 10 8.9 4.9  
11750 6.5 43.7 200 15 8 9.2 5.1 | 8.0 46.4 190 19 10 9.4 5.2  
11500 7.2 45.0 200 14 7 9.8 5.4 | 8.6 47.5 190 18 9 8.9 4.9  
11250 7.9 46.2 195 14 7 10.1 5.5 | 9.3 48.7 185 18 9 8.8 4.9  
11000 8.7 47.7 195 13 7 9.0 4.9 | 10.0 50.0 185 18 9 8.8 4.8  
10750 9.3 48.7 190 13 7 7.7 4.2 | 10.6 51.1 185 17 9 8.6 4.7  
10500 9.9 49.8 190 12 6 9.3 5.1 | 11.3 52.3 185 17 9 9.2 5.0  
10250 10.7 51.3 190 12 6 12.3 6.7 | 12.0 53.6 185 17 9 10.4 5.7  
10000 11.6 52.9 190 12 6 10.8 5.9 | 12.8 55.0 180 16 8 9.8 5.4  
9750 12.3 54.1 185 12 6 9.1 5.0 | 13.4 56.1 180 16 8 9.2 5.1  
9500 13.0 55.4 185 12 6 8.9 4.9 | 14.1 57.4 180 16 8 9.0 4.9  
9250 13.7 56.7 185 12 6 11.4 6.3 | 14.8 58.6 180 15 8 10.4 5.7  
9000 14.6 58.3 185 12 6 11.7 6.4 | 15.6 60.1 180 15 8 10.6 5.8  
8750 15.3 59.5 185 11 6 9.3 5.1 | 16.4 61.5 180 15 8 9.1 5.0  
8500 16.1 61.0 185 11 6 9.5 5.2 | 17.1 62.8 175 14 7 9.7 5.3  
8250 16.8 62.2 185 11 6 11.0 6.1 | 17.8 64.0 175 14 7 8.8 4.8  
8000 17.9 64.2 185 11 6 18.0 9.9 | 18.4 65.1 175 13 7 8.5 4.6  
7750 19.4 66.9 180 10 5 24.1 13.2 | 19.0 66.2 175 10 5 10.1 5.5  
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