754
UXUS97 KPUB 131212
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO, COLORADO
0612 MDT SATURDAY, SEPTEMBER 13, 2025
THIS FORECAST IS FOR SATURDAY, SEPTEMBER 13, 2025:
IF THE TRIGGER TEMPERATURE OF 65.4 F/18.5 C IS REACHED...THEN
THERMAL SOARING INDEX....................... FAIR
MAXIMUM RATE OF LIFT........................ 387 FT/MIN (2.0 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 16300 FT MSL (8682 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 73.0 F/23.2 C
TIME OF TRIGGER TEMPERATURE.................... 0945 MDT
TIME OF OVERDEVELOPMENT........................ 1200 MDT
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................. 13017 FT MSL (5400 FT AGL)
THERMAL SOARING OUTLOOK FOR SUNDAY 09/14....... GOOD
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 06:39:28 / 19:10:36 MDT
TOTAL POSSIBLE SUNSHINE........... 12 HR 31 MIN 7 SEC (751 MIN 7 SEC)
ALTITUDE OF SUN AT 12:55:02 MDT... 54.47 DEGREES
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 09/13/2025 AT 0600 MDT
FREEZING LEVEL.................. 14783 FT MSL (7165 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 14382 FT MSL (6764 FT AGL)
LIFTED CONDENSATION LEVEL....... 15076 FT MSL (7458 FT AGL)
LIFTED INDEX.................... -3.5
K INDEX......................... +18.7
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 -63.6 -82.5 225 35 18 2.5 1.4 M M M M M
45000 -59.1 -74.4 235 50 26 4.7 2.6 M M M M M
40000 -51.5 -60.7 225 71 37 5.4 3.0 M M M M M
38000 -48.3 -54.9 220 73 38 5.4 3.0 M M M M M
36000 -45.0 -49.0 215 77 39 5.4 3.0 M M M M M
34000 -40.9 -41.6 210 77 39 7.2 3.9 M M M M M
32000 -36.6 -33.9 205 76 39 7.2 4.0 M M M M M
30000 -32.1 -25.8 205 72 37 7.7 4.2 36.9 98.4 11.0 M M
29000 -29.8 -21.6 210 70 36 7.7 4.2 36.1 97.0 10.5 M M
28000 -27.4 -17.3 210 68 35 8.0 4.4 35.5 95.9 10.1 M M
27000 -25.6 -14.1 210 63 33 5.8 3.2 34.1 93.4 9.1 M M
26000 -23.8 -10.8 210 57 30 5.8 3.2 32.6 90.7 8.0 M M
25000 -22.1 -7.8 210 52 27 5.8 3.2 31.2 88.2 7.0 M M
24000 -19.5 -3.1 215 48 25 7.9 4.3 30.0 86.0 6.0 M M
23000 -17.1 1.2 215 48 25 7.9 4.3 29.3 84.8 5.5 M M
22000 -14.7 5.5 220 47 24 7.9 4.3 28.8 83.8 5.1 M M
21000 -12.6 9.3 225 41 21 7.0 3.9 27.8 82.0 4.2 M M
20000 -10.6 12.9 225 33 17 7.2 4.0 26.9 80.4 3.4 M M
19500 -9.6 14.7 230 29 15 7.4 4.0 26.5 79.7 3.0 M M
19000 -8.5 16.7 230 26 13 7.1 3.9 26.1 79.0 2.6 M M
18500 -7.4 18.7 235 23 12 7.1 3.9 25.6 78.2 2.2 M M
18000 -6.4 20.5 240 20 10 6.9 3.8 25.2 77.4 1.9 M M
17500 -5.4 22.3 245 19 10 6.1 3.3 24.6 76.3 1.3 M M
17000 -4.6 23.7 245 19 10 6.1 3.3 24.0 75.2 0.8 M M
16500 -3.7 25.3 250 18 9 6.8 3.7 23.5 74.2 0.2 M M
16000 -2.7 27.1 250 16 8 7.0 3.8 23.0 73.4 -0.3 760 3.9
15500 -1.8 28.8 250 14 7 7.6 4.2 22.5 72.6 -0.8 716 3.6
15000 -0.6 30.9 240 11 6 8.1 4.5 22.3 72.1 -1.1 666 3.4
14500 0.6 33.1 235 9 5 7.9 4.4 22.0 71.7 -1.4 615 3.1
14000 1.6 34.9 230 9 5 6.4 3.5 21.6 70.8 -1.9 571 2.9
13500 2.5 36.5 225 10 5 6.5 3.6 21.1 69.9 -2.4 529 2.7
13000 3.4 38.1 225 11 6 7.2 3.9 20.6 69.1 -3.0 486 2.5
12500 4.5 40.1 230 11 6 7.3 4.0 20.2 68.4 -3.5 441 2.2
12000 5.6 42.1 240 11 6 8.4 4.6 19.9 67.8 -3.8 393 2.0
11750 6.2 43.2 245 11 6 8.4 4.6 19.8 67.7 -4.0 368 1.9
11500 6.8 44.2 250 11 6 7.9 4.3 19.7 67.4 -4.1 343 1.7
11250 7.3 45.1 250 11 6 7.1 3.9 19.5 67.1 -4.3 319 1.6
11000 7.8 46.0 250 12 6 6.6 3.6 19.3 66.7 -4.6 297 1.5
10750 8.3 46.9 250 12 6 6.3 3.4 19.0 66.2 -4.8 276 1.4
10500 8.7 47.7 250 12 6 7.3 4.0 18.8 65.8 -5.1 254 1.3
10250 9.3 48.7 250 12 6 8.1 4.5 18.6 65.6 -5.2 229 1.2
10000 9.9 49.8 250 12 6 6.8 3.7 18.5 65.2 -5.4 204 1.0
9750 10.4 50.7 250 11 6 6.1 3.4 18.2 64.8 -5.7 183 0.9
9500 10.8 51.4 250 11 5 6.6 3.6 17.9 64.3 -6.0 162 0.8
9250 11.3 52.3 250 10 5 5.5 3.0 17.7 63.8 -6.3 141 0.7
9000 11.6 52.9 250 10 5 4.9 2.7 17.3 63.2 -6.6 122 0.6
8750 12.0 53.6 245 10 5 5.1 2.8 17.0 62.5 -7.0 104 0.5
8500 12.4 54.3 245 10 5 6.1 3.4 16.6 61.9 -7.4 85 0.4
8250 12.7 54.9 245 10 5 1.7 0.9 16.3 61.3 -7.8 67 0.3
8000 12.4 54.3 235 9 4 -9.0 -4.9 15.3 59.5 -8.9 70 0.4
7750 11.5 52.7 230 6 3 -13.4 -7.3 13.6 56.5 -10.6 90 0.5
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 * * * * * *
09/13/2025 AT 0900 MDT | 09/13/2025 AT 1200 MDT
|
CAPE... +233.1 LI... -1.0 | CAPE... +591.8 LI... -3.8
CINH... -56.7 K INDEX... +16.2 | CINH... -1.0 K INDEX... +23.3
|
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 -62.4 -80.3 225 36 19 2.4 1.3 | -61.7 -79.1 225 35 18 3.0 1.6
45000 -58.0 -72.4 225 48 25 4.8 2.6 | -57.1 -70.8 220 49 25 3.4 1.9
40000 -50.5 -58.9 225 77 40 4.1 2.2 | -51.6 -60.9 220 80 41 4.9 2.7
38000 -48.0 -54.4 220 84 43 4.1 2.2 | -48.7 -55.7 210 82 42 4.8 2.6
36000 -45.6 -50.1 210 92 48 4.2 2.3 | -45.8 -50.4 195 87 45 4.9 2.7
34000 -41.4 -42.5 210 89 46 7.9 4.3 | -41.2 -42.2 200 87 45 8.7 4.8
32000 -36.7 -34.1 210 81 42 7.8 4.3 | -36.0 -32.8 200 85 44 8.7 4.8
30000 -32.8 -27.0 210 74 38 5.7 3.2 | -32.0 -25.6 205 81 42 5.7 3.1
29000 -31.1 -24.0 210 71 36 5.7 3.2 | -30.3 -22.5 205 78 40 5.7 3.1
28000 -29.4 -20.9 210 67 35 5.6 3.1 | -28.6 -19.5 205 76 39 5.7 3.1
27000 -27.3 -17.1 210 62 32 7.4 4.1 | -26.9 -16.4 210 71 36 5.7 3.1
26000 -25.1 -13.2 215 57 29 7.4 4.1 | -25.1 -13.2 215 64 33 5.7 3.1
25000 -22.9 -9.2 215 52 27 7.4 4.1 | -23.4 -10.1 220 58 30 5.7 3.1
24000 -20.5 -4.9 220 47 24 8.4 4.6 | -21.0 -5.8 225 50 26 6.9 3.8
23000 -17.3 0.9 225 40 21 8.4 4.6 | -18.9 -2.0 225 43 22 6.9 3.8
22000 -14.8 5.4 225 35 18 8.2 4.5 | -16.9 1.6 230 36 18 6.9 3.8
21000 -12.9 8.8 225 30 16 5.9 3.2 | -14.8 5.4 230 30 16 7.0 3.9
20000 -11.2 11.8 230 27 14 6.0 3.3 | -12.7 9.1 220 26 13 7.2 4.0
19500 -10.3 13.5 230 25 13 6.0 3.3 | -11.7 10.9 215 24 12 7.3 4.0
19000 -9.3 15.3 230 23 12 7.4 4.0 | -10.6 12.9 210 22 11 8.2 4.5
18500 -8.2 17.2 225 21 11 7.5 4.1 | -9.4 15.1 205 21 11 8.3 4.6
18000 -7.1 19.2 220 19 10 7.1 3.9 | -8.2 17.2 200 20 10 8.1 4.4
17500 -6.3 20.7 220 17 9 5.8 3.2 | -7.2 19.0 200 19 10 6.4 3.5
17000 -5.5 22.1 215 15 8 6.2 3.4 | -6.3 20.7 200 17 9 6.6 3.6
16500 -4.6 23.7 220 13 6 7.4 4.1 | -5.4 22.3 200 15 8 7.0 3.8
16000 -3.5 25.7 225 11 6 7.5 4.1 | -4.4 24.1 200 13 7 7.1 3.9
15500 -2.5 27.5 230 10 5 7.8 4.3 | -3.4 25.9 200 11 6 7.7 4.2
15000 -1.3 29.7 230 9 5 8.1 4.4 | -2.2 28.0 200 10 5 8.3 4.6
14500 -0.2 31.6 230 8 4 8.1 4.4 | -1.0 30.2 205 9 5 8.3 4.5
14000 0.9 33.6 235 8 4 7.8 4.3 | 0.1 32.2 205 8 4 7.7 4.2
13500 2.1 35.8 235 8 4 7.8 4.3 | 1.3 34.3 210 6 3 7.7 4.2
13000 3.3 37.9 240 8 4 8.8 4.8 | 2.5 36.5 220 5 3 9.2 5.1
12500 4.4 39.9 245 8 4 6.9 3.8 | 3.6 38.5 230 4 2 6.7 3.7
12000 5.5 41.9 255 9 5 8.1 4.4 | 4.6 40.3 225 2 1 6.4 3.5
11750 6.1 43.0 260 10 5 8.0 4.4 | 5.0 41.0 190 1 0 6.7 3.7
11500 6.7 44.1 260 10 5 8.2 4.5 | 5.5 41.9 115 1 1 8.9 4.9
11250 7.3 45.1 265 10 5 7.6 4.2 | 6.2 43.2 100 2 1 9.7 5.3
11000 7.8 46.0 270 10 5 6.9 3.8 | 6.8 44.2 095 3 1 8.9 4.9
10750 8.3 46.9 270 9 5 6.6 3.6 | 7.5 45.5 095 3 2 8.7 4.7
10500 8.8 47.8 275 9 5 7.8 4.3 | 8.2 46.8 095 3 2 9.8 5.4
10250 9.4 48.9 280 9 4 8.3 4.6 | 8.9 48.0 095 4 2 11.0 6.0
10000 9.9 49.8 285 8 4 6.9 3.8 | 9.7 49.5 095 4 2 9.9 5.4
9750 10.4 50.7 285 8 4 6.6 3.6 | 10.5 50.9 095 4 2 9.6 5.3
9500 10.9 51.6 290 7 4 6.9 3.8 | 11.2 52.2 095 4 2 9.5 5.2
9250 11.4 52.5 295 7 4 5.9 3.3 | 11.9 53.4 095 4 2 10.3 5.6
9000 11.8 53.2 300 7 4 6.3 3.4 | 12.7 54.9 095 4 2 10.7 5.9
8750 12.3 54.1 305 7 4 7.5 4.1 | 13.4 56.1 095 4 2 10.2 5.6
8500 12.8 55.0 305 7 4 7.1 3.9 | 14.2 57.6 095 4 2 10.2 5.6
8250 13.3 55.9 310 7 4 7.1 3.9 | 15.0 59.0 095 4 2 10.9 6.0
8000 13.9 57.0 310 7 3 10.5 5.7 | 15.9 60.6 095 4 2 15.7 8.6
7750 14.9 58.8 305 5 3 16.4 9.0 | 17.3 63.1 095 5 2 21.4 11.8
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
09/13/2025 AT 1500 MDT | 09/13/2025 AT 1800 MDT
|
CAPE... +697.9 LI... -3.5 | CAPE... +1052.6 LI... -2.8
CINH... -0.7 K INDEX... +26.3 | CINH... -2.2 K INDEX... +32.6
|
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 -61.1 -78.0 225 31 16 2.0 1.1 | -60.8 -77.4 215 29 15 2.1 1.2
45000 -57.6 -71.7 215 50 26 3.7 2.0 | -56.9 -70.4 210 45 23 4.0 2.2
40000 -52.0 -61.6 215 67 34 4.5 2.5 | -50.9 -59.6 215 44 22 3.9 2.1
38000 -48.6 -55.5 210 69 36 5.1 2.8 | -48.3 -54.9 210 51 26 3.8 2.1
36000 -45.5 -49.9 205 72 37 5.1 2.8 | -46.1 -51.0 205 58 30 3.8 2.1
34000 -41.7 -43.1 205 72 37 7.0 3.8 | -42.6 -44.7 200 60 31 6.8 3.7
32000 -37.5 -35.5 205 71 36 7.0 3.8 | -38.5 -37.3 195 60 31 6.8 3.7
30000 -33.8 -28.8 205 69 36 5.7 3.1 | -34.8 -30.6 200 54 28 5.8 3.2
29000 -32.0 -25.6 210 69 35 5.7 3.1 | -33.1 -27.6 210 51 26 5.8 3.2
28000 -30.3 -22.5 210 68 35 5.6 3.1 | -31.3 -24.3 220 48 25 5.7 3.1
27000 -28.3 -18.9 215 65 33 7.1 3.9 | -29.3 -20.7 225 44 23 7.3 4.0
26000 -26.2 -15.2 215 59 31 7.1 3.9 | -27.1 -16.8 235 39 20 7.3 4.0
25000 -24.1 -11.4 220 54 28 7.2 3.9 | -24.9 -12.8 245 36 18 7.4 4.1
24000 -21.8 -7.2 225 50 26 8.3 4.6 | -22.5 -8.5 250 34 17 9.4 5.2
23000 -19.3 -2.7 230 48 25 8.3 4.6 | -19.7 -3.5 255 33 17 9.5 5.2
22000 -16.1 3.0 235 45 23 8.5 4.7 | -16.2 2.8 255 32 16 9.9 5.4
21000 -14.2 6.4 235 41 21 6.0 3.3 | -13.9 7.0 255 29 15 7.6 4.2
20000 -12.4 9.7 235 37 19 6.2 3.4 | -11.7 10.9 250 25 13 7.7 4.2
19500 -11.5 11.3 235 35 18 6.3 3.5 | -10.6 12.9 245 23 12 7.7 4.2
19000 -10.6 12.9 235 33 17 7.1 3.9 | -9.5 14.9 240 22 11 6.4 3.5
18500 -9.6 14.7 235 31 16 7.4 4.1 | -8.7 16.3 240 21 11 5.9 3.2
18000 -8.6 16.5 230 28 15 7.7 4.2 | -7.8 18.0 235 21 11 5.9 3.2
17500 -7.4 18.7 230 26 13 8.6 4.7 | -6.9 19.6 230 20 10 7.0 3.8
17000 -6.2 20.8 225 23 12 8.7 4.8 | -5.9 21.4 225 20 10 6.9 3.8
16500 -5.0 23.0 225 21 11 8.2 4.5 | -4.9 23.2 225 20 10 6.7 3.7
16000 -3.8 25.2 220 20 10 8.2 4.5 | -3.9 25.0 220 19 10 6.7 3.7
15500 -2.6 27.3 215 18 9 8.1 4.5 | -3.0 26.6 215 19 10 6.8 3.7
15000 -1.5 29.3 210 17 9 8.0 4.4 | -2.0 28.4 215 20 10 7.0 3.8
14500 -0.3 31.5 205 16 8 8.0 4.4 | -1.0 30.2 210 20 10 7.0 3.8
14000 0.8 33.4 200 15 8 7.8 4.3 | 0.0 32.0 205 20 10 7.4 4.0
13500 2.0 35.6 195 14 7 7.6 4.2 | 1.1 34.0 200 20 10 7.1 3.9
13000 3.2 37.8 185 13 6 8.9 4.9 | 2.2 36.0 195 20 10 9.1 5.0
12500 4.3 39.7 180 12 6 7.0 3.8 | 3.3 37.9 195 20 10 6.7 3.7
12000 5.4 41.7 175 13 6 7.6 4.2 | 4.4 39.9 190 19 10 9.1 5.0
11750 5.9 42.6 170 13 7 8.0 4.4 | 5.1 41.2 190 19 10 9.4 5.1
11500 6.5 43.7 170 13 7 9.7 5.3 | 5.8 42.4 195 19 10 9.3 5.1
11250 7.3 45.1 165 14 7 9.9 5.4 | 6.5 43.7 195 19 10 9.1 5.0
11000 7.9 46.2 165 14 7 8.8 4.8 | 7.1 44.8 190 19 10 8.9 4.9
10750 8.5 47.3 165 14 7 8.1 4.4 | 7.8 46.0 190 18 9 8.5 4.7
10500 9.2 48.6 165 15 8 10.1 5.5 | 8.4 47.1 190 18 9 9.4 5.2
10250 10.0 50.0 165 15 8 12.3 6.8 | 9.2 48.6 190 18 9 10.8 5.9
10000 10.9 51.6 165 15 8 10.2 5.6 | 10.0 50.0 190 17 9 10.1 5.6
9750 11.6 52.9 165 15 8 9.1 5.0 | 10.7 51.3 190 17 9 9.4 5.2
9500 12.3 54.1 165 15 8 9.1 5.0 | 11.4 52.5 190 17 9 9.6 5.3
9250 13.0 55.4 160 15 8 10.3 5.7 | 12.1 53.8 190 16 8 9.7 5.3
9000 13.8 56.8 160 15 8 11.0 6.0 | 12.8 55.0 190 16 8 9.8 5.4
8750 14.6 58.3 160 15 8 10.2 5.6 | 13.6 56.5 190 15 8 9.7 5.3
8500 15.3 59.5 160 15 8 10.2 5.6 | 14.3 57.7 190 15 8 9.7 5.3
8250 16.1 61.0 160 15 8 11.0 6.0 | 15.0 59.0 190 15 7 9.7 5.3
8000 17.1 62.8 160 15 8 17.5 9.6 | 15.7 60.3 190 13 7 10.1 5.5
7750 18.7 65.7 160 14 7 25.5 14.0 | 16.5 61.7 190 11 6 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) 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 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.
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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