904
UXUS97 KPUB 051216
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO, COLORADO
0615 MDT TUESDAY, AUGUST 5, 2025
THIS FORECAST IS FOR VILLA GROVE, CO FOR TUESDAY, AUGUST 5, 2025:
IF THE TRIGGER TEMPERATURE OF 70.6 F/21.5 C IS REACHED...THEN
THERMAL SOARING INDEX....................... EXCELLENT
MAXIMUM RATE OF LIFT........................ 1667 FT/MIN (8.5 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 25502 FT MSL (16523 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 85.0 F/29.9 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................. 21324 FT MSL (12344 FT AGL)
THERMAL SOARING OUTLOOK FOR WEDNESDAY 08/06.... EXCELLENT
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 06:10:04 / 20:09:01 MDT
TOTAL POSSIBLE SUNSHINE........... 13 HR 58 MIN 56 SEC (838 MIN 56 SEC)
ALTITUDE OF SUN AT 13:09:32 MDT... 68.37 DEGREES
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 08/05/2025 AT 0600 MDT
FREEZING LEVEL.................. 16580 FT MSL (7601 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 23872 FT MSL (14893 FT AGL)
LIFTED CONDENSATION LEVEL....... 24694 FT MSL (15714 FT AGL)
LIFTED INDEX.................... -0.7
K INDEX......................... -2.4
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 -64.5 -84.1 250 34 18 -0.5 -0.3 M M M M M
45000 -62.3 -80.1 255 51 26 6.1 3.3 M M M M M
40000 -52.3 -62.1 255 48 25 7.7 4.2 M M M M M
38000 -47.7 -53.9 260 46 24 7.7 4.2 M M M M M
36000 -43.1 -45.6 260 44 23 7.5 4.1 M M M M M
34000 -39.0 -38.2 265 49 25 6.9 3.8 M M M M M
32000 -34.8 -30.6 270 54 28 6.8 3.7 M M M M M
30000 -30.5 -22.9 270 51 26 7.3 4.0 33.9 93.1 3.5 M M
29000 -28.3 -18.9 270 48 25 7.3 4.0 33.1 91.5 2.8 M M
28000 -25.6 -14.1 270 45 23 7.0 3.8 32.0 89.6 2.0 M M
27000 -23.5 -10.3 270 43 22 7.0 3.8 30.9 87.6 1.1 M M
26000 -21.4 -6.5 270 40 21 7.0 3.8 29.9 85.8 0.3 M M
25000 -19.3 -2.7 270 38 20 7.1 3.9 29.0 84.3 -0.4 1614 8.2
24000 -17.2 1.0 265 36 18 7.2 3.9 28.0 82.5 -1.3 1520 7.7
23000 -15.0 5.0 265 34 17 7.2 3.9 27.1 80.9 -2.0 1426 7.2
22000 -12.8 9.0 265 31 16 8.3 4.6 26.4 79.5 -2.7 1330 6.8
21000 -10.2 13.6 260 25 13 8.7 4.8 26.0 78.7 -3.1 1223 6.2
20000 -7.6 18.3 255 19 10 8.7 4.8 25.6 78.1 -3.5 1116 5.7
19500 -6.3 20.7 250 17 9 8.6 4.7 25.5 77.9 -3.6 1063 5.4
19000 -5.1 22.8 250 16 8 8.0 4.4 25.2 77.4 -3.9 1011 5.1
18500 -3.9 25.0 255 17 9 8.1 4.4 24.9 76.9 -4.2 961 4.9
18000 -2.8 27.0 255 17 9 6.6 3.6 24.6 76.3 -4.5 913 4.6
17500 -1.9 28.6 255 18 9 6.3 3.4 24.0 75.2 -5.1 871 4.4
17000 -1.0 30.2 255 19 10 6.5 3.5 23.4 74.2 -5.7 830 4.2
16500 -0.0 32.0 255 20 10 7.3 4.0 23.0 73.4 -6.2 785 4.0
16000 1.0 33.8 255 20 10 7.1 3.9 22.6 72.7 -6.7 738 3.8
15500 2.2 36.0 260 21 11 9.1 5.0 22.3 72.2 -7.0 689 3.5
15000 3.5 38.3 260 22 11 9.2 5.0 22.2 72.0 -7.2 634 3.2
14500 5.4 41.7 265 23 12 8.7 4.8 22.0 71.5 -7.5 555 2.8
14000 6.8 44.2 265 24 12 9.4 5.2 21.9 71.5 -7.6 499 2.5
13500 8.3 46.9 265 24 13 10.8 5.9 22.0 71.6 -7.6 440 2.2
13000 9.7 49.5 270 26 13 8.6 4.7 21.9 71.5 -7.7 382 1.9
12500 11.1 52.0 270 28 14 9.3 5.1 21.8 71.3 -7.9 327 1.7
12000 12.5 54.5 270 27 14 9.1 5.0 21.8 71.2 -7.9 269 1.4
11750 13.2 55.8 270 27 14 8.8 4.9 21.7 71.1 -8.0 242 1.2
11500 13.8 56.8 270 27 14 8.3 4.5 21.6 70.9 -8.1 214 1.1
11250 14.4 57.9 270 27 14 8.0 4.4 21.5 70.7 -8.2 189 1.0
11000 15.0 59.0 270 27 14 7.3 4.0 21.3 70.4 -8.4 164 0.8
10750 15.6 60.1 270 27 14 11.2 6.2 21.2 70.2 -8.5 138 0.7
10500 16.4 61.5 275 27 14 3.7 2.0 21.3 70.3 -8.5 107 0.5
10250 16.2 61.2 270 26 13 -4.7 -2.6 20.3 68.5 -9.5 107 0.5
10000 15.9 60.6 270 24 12 -5.0 -2.7 19.3 66.7 -10.5 107 0.5
9750 15.7 60.3 265 22 11 4.5 2.5 18.3 64.9 -11.5 107 0.5
9500 16.0 60.8 265 20 10 -10.0 -5.5 17.9 64.2 -11.9 89 0.5
9250 13.2 55.8 260 13 7 -64.4 -35.3 14.3 57.8 -15.5 166 0.8
9000 10.4 50.7 240 7 3 41.2 22.6 10.8 51.4 -19.1 244 1.2
8750 M M M M M M M M M M M M
8500 M M M M M M M M M M M M
8250 M M M M M M M M M M M M
8000 M M M M M M M M M M M M
* * * * * * NUMERICAL WEATHER PREDICTION MODEL FORECAST DATA VALID * * * * * *
08/05/2025 AT 0900 MDT | 08/05/2025 AT 1200 MDT
|
CAPE... 0.0 LI... +1.4 | CAPE... 0.0 LI... +1.9
CINH... 0.0 K INDEX... -1.1 | CINH... 0.0 K INDEX... -5.2
|
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 -65.5 -85.9 250 33 17 0.3 0.2 | -64.7 -84.5 255 39 20 -0.7 -0.4
45000 -62.4 -80.3 255 49 25 5.9 3.2 | -62.7 -80.9 260 57 29 5.8 3.2
40000 -52.7 -62.9 255 50 26 7.8 4.3 | -53.2 -63.8 255 51 26 7.4 4.1
38000 -48.0 -54.4 260 48 25 7.8 4.3 | -48.8 -55.8 260 49 25 7.4 4.1
36000 -43.3 -45.9 260 47 24 7.6 4.2 | -44.3 -47.7 260 47 24 7.7 4.2
34000 -38.9 -38.0 265 48 25 7.3 4.0 | -39.5 -39.1 265 45 23 8.1 4.4
32000 -34.5 -30.1 270 51 26 7.9 4.3 | -34.7 -30.5 270 43 22 8.7 4.8
30000 -30.3 -22.5 275 47 24 6.9 3.8 | -30.5 -22.9 270 39 20 6.9 3.8
29000 -27.8 -18.0 275 45 23 6.9 3.8 | -28.0 -18.4 270 35 18 6.9 3.8
28000 -25.7 -14.3 275 43 22 7.2 4.0 | -25.8 -14.4 270 34 17 7.6 4.2
27000 -23.5 -10.3 270 41 21 7.2 4.0 | -23.5 -10.3 270 34 17 7.6 4.2
26000 -21.4 -6.5 270 39 20 7.2 4.0 | -21.3 -6.3 270 34 17 7.6 4.2
25000 -19.2 -2.6 265 38 19 7.1 3.9 | -19.0 -2.2 265 33 17 7.6 4.2
24000 -17.0 1.4 265 35 18 7.2 3.9 | -16.7 1.9 265 31 16 7.6 4.2
23000 -14.9 5.2 260 32 17 7.2 4.0 | -14.5 5.9 265 29 15 7.6 4.2
22000 -12.7 9.1 260 30 15 7.6 4.2 | -12.2 10.0 265 27 14 7.7 4.2
21000 -10.4 13.3 260 28 14 7.7 4.2 | -9.9 14.2 260 24 12 7.7 4.2
20000 -8.1 17.4 260 27 14 7.8 4.3 | -7.5 18.5 255 21 11 7.8 4.3
19500 -7.0 19.4 260 26 13 8.0 4.4 | -6.3 20.7 250 20 10 8.0 4.4
19000 -5.7 21.7 265 25 13 8.4 4.6 | -5.1 22.8 245 17 9 8.3 4.6
18500 -4.5 23.9 265 25 13 8.4 4.6 | -3.8 25.2 235 15 8 8.4 4.6
18000 -3.3 26.1 265 24 12 8.1 4.4 | -2.6 27.3 230 14 7 7.7 4.2
17500 -2.1 28.2 260 24 12 8.0 4.4 | -1.5 29.3 240 16 8 7.6 4.2
17000 -0.9 30.4 260 24 12 8.0 4.4 | -0.4 31.3 250 18 9 7.3 4.0
16500 0.2 32.4 255 23 12 7.9 4.3 | 0.6 33.1 255 22 11 6.9 3.8
16000 1.4 34.5 255 22 11 7.9 4.3 | 1.6 34.9 260 26 13 6.8 3.7
15500 2.6 36.7 255 22 11 8.3 4.6 | 2.7 36.9 260 28 14 8.5 4.7
15000 4.4 39.9 255 23 12 8.3 4.6 | 4.4 39.9 260 26 14 8.4 4.6
14500 5.6 42.1 255 23 12 8.7 4.8 | 5.7 42.3 260 25 13 9.9 5.4
14000 6.8 44.2 255 22 11 8.7 4.8 | 7.2 45.0 260 24 12 10.0 5.5
13500 8.2 46.8 250 22 11 10.1 5.5 | 8.8 47.8 260 23 12 10.8 5.9
13000 9.4 48.9 255 22 11 7.3 4.0 | 10.2 50.4 260 22 11 9.0 4.9
12500 10.6 51.1 255 21 11 7.9 4.3 | 11.7 53.1 260 22 11 10.1 5.5
12000 11.7 53.1 260 20 10 6.8 3.7 | 13.2 55.8 260 21 11 9.4 5.2
11750 12.2 54.0 265 20 11 5.6 3.1 | 13.8 56.8 260 21 11 9.0 5.0
11500 12.7 54.9 270 21 11 7.1 3.9 | 14.5 58.1 260 21 11 10.1 5.5
11250 13.3 55.9 270 22 11 7.7 4.2 | 15.3 59.5 260 20 11 10.4 5.7
11000 13.9 57.0 275 23 12 7.5 4.1 | 16.1 61.0 260 20 10 10.3 5.7
10750 14.5 58.1 275 24 13 7.9 4.3 | 16.9 62.4 260 20 10 10.5 5.8
10500 15.1 59.2 280 24 12 6.8 3.7 | 17.7 63.9 260 20 10 10.7 5.9
10250 15.5 59.9 275 22 12 5.8 3.2 | 18.5 65.3 260 19 10 10.8 5.9
10000 16.0 60.8 275 21 11 6.0 3.3 | 19.3 66.7 260 19 10 10.8 5.9
9750 16.5 61.7 275 19 10 6.4 3.5 | 20.1 68.2 260 18 9 10.6 5.8
9500 17.0 62.6 270 16 8 10.4 5.7 | 21.0 69.8 260 17 9 17.9 9.8
9250 18.0 64.4 270 13 6 15.7 8.6 | 22.8 73.0 260 16 8 30.3 16.6
9000 18.9 66.0 260 9 5 6.9 3.8 | 24.6 76.3 260 14 7 8.2 4.5
8750 M M M M M M M | M M M M M M M
8500 M M M M M M M | M M M M M M M
8250 M M M M M M M | M M M M M M M
8000 M M M M M M M | M M M M M M M
08/05/2025 AT 1500 MDT | 08/05/2025 AT 1800 MDT
|
CAPE... 0.0 LI... -0.4 | CAPE... 0.0 LI... -0.1
CINH... 0.0 K INDEX... +2.9 | CINH... 0.0 K INDEX... +8.4
|
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 -64.1 -83.4 265 39 20 -1.3 -0.7 | -64.6 -84.3 275 38 20 -1.1 -0.6
45000 -62.9 -81.2 270 64 33 5.4 2.9 | -62.8 -81.0 280 63 33 5.6 3.1
40000 -53.9 -65.0 265 60 31 7.8 4.3 | -53.8 -64.8 275 58 30 8.0 4.4
38000 -49.2 -56.6 265 53 28 7.8 4.3 | -49.0 -56.2 275 51 26 8.0 4.4
36000 -44.6 -48.3 265 47 24 8.0 4.4 | -44.3 -47.7 275 43 22 7.9 4.3
34000 -39.7 -39.5 265 45 23 8.2 4.5 | -39.6 -39.3 275 44 23 7.8 4.3
32000 -34.8 -30.6 265 43 22 8.7 4.8 | -34.9 -30.8 275 44 23 8.4 4.6
30000 -30.7 -23.3 260 38 20 6.7 3.7 | -30.4 -22.7 270 41 21 6.6 3.6
29000 -28.2 -18.8 260 35 18 6.7 3.7 | -28.5 -19.3 265 40 20 6.6 3.6
28000 -26.1 -15.0 255 34 17 7.7 4.3 | -26.3 -15.3 265 38 20 7.8 4.3
27000 -23.7 -10.7 260 33 17 7.7 4.2 | -24.0 -11.2 265 35 18 7.8 4.3
26000 -21.4 -6.5 260 32 16 7.7 4.2 | -21.7 -7.1 265 33 17 7.8 4.3
25000 -19.2 -2.6 265 31 16 7.2 4.0 | -19.4 -2.9 265 30 15 7.1 3.9
24000 -17.0 1.4 265 28 14 7.2 4.0 | -17.4 0.7 260 27 14 7.1 3.9
23000 -14.9 5.2 265 25 13 7.2 4.0 | -15.3 4.5 255 24 12 7.1 3.9
22000 -12.7 9.1 265 23 12 8.0 4.4 | -13.1 8.4 250 22 11 8.7 4.8
21000 -10.3 13.5 265 22 11 8.0 4.4 | -10.5 13.1 250 21 11 8.7 4.8
20000 -7.9 17.8 270 21 11 8.1 4.4 | -8.0 17.6 250 20 10 8.7 4.8
19500 -6.6 20.1 270 20 10 8.3 4.6 | -6.7 19.9 250 19 10 8.9 4.9
19000 -5.4 22.3 270 20 10 8.6 4.7 | -5.3 22.5 255 19 10 9.2 5.0
18500 -4.1 24.6 270 20 10 8.5 4.7 | -3.9 25.0 255 19 10 9.2 5.1
18000 -2.8 27.0 270 20 10 9.2 5.0 | -2.5 27.5 255 19 10 9.1 5.0
17500 -1.5 29.3 270 19 10 9.2 5.0 | -1.1 30.0 260 19 10 9.1 5.0
17000 -0.1 31.8 270 19 10 9.5 5.2 | 0.2 32.4 260 19 10 9.0 4.9
16500 1.3 34.3 270 18 9 9.8 5.4 | 1.6 34.9 265 19 10 8.8 4.8
16000 2.8 37.0 270 18 9 9.8 5.4 | 2.9 37.2 270 19 10 8.8 4.8
15500 4.3 39.7 270 18 9 9.8 5.4 | 4.3 39.7 270 19 10 9.3 5.1
15000 5.7 42.3 270 18 9 9.8 5.4 | 6.4 43.5 275 19 10 9.5 5.2
14500 7.9 46.2 270 17 9 9.7 5.3 | 7.8 46.0 275 18 9 9.6 5.3
14000 9.4 48.9 270 17 9 9.5 5.2 | 9.2 48.6 275 17 9 9.4 5.2
13500 11.0 51.8 275 17 9 11.7 6.4 | 10.7 51.3 280 17 9 10.7 5.9
13000 12.4 54.3 275 17 9 8.7 4.8 | 12.2 54.0 280 16 8 9.2 5.1
12500 13.9 57.0 275 16 8 10.4 5.7 | 13.6 56.5 280 16 8 10.1 5.6
12000 15.4 59.7 275 16 8 9.7 5.3 | 15.1 59.2 285 15 8 9.5 5.2
11750 16.1 61.0 275 16 8 9.2 5.1 | 15.8 60.4 285 15 8 9.1 5.0
11500 16.8 62.2 275 16 8 9.7 5.3 | 16.5 61.7 285 15 8 9.5 5.2
11250 17.5 63.5 275 16 8 9.8 5.4 | 17.3 63.1 285 15 8 9.6 5.3
11000 18.3 64.9 275 16 8 9.8 5.4 | 18.0 64.4 285 15 8 9.6 5.3
10750 19.0 66.2 275 15 8 10.5 5.8 | 18.7 65.7 285 14 7 9.9 5.5
10500 19.8 67.6 275 15 8 10.8 5.9 | 19.5 67.1 285 14 7 10.3 5.7
10250 20.6 69.1 275 15 8 10.6 5.8 | 20.2 68.4 285 14 7 10.2 5.6
10000 21.4 70.5 275 14 7 10.7 5.9 | 21.0 69.8 285 13 7 10.5 5.7
9750 22.2 72.0 275 14 7 10.4 5.7 | 21.8 71.2 285 13 7 9.7 5.3
9500 23.1 73.6 275 14 7 16.6 9.1 | 22.5 72.5 285 12 6 11.1 6.1
9250 24.8 76.6 275 13 6 27.3 15.0 | 23.5 74.3 285 11 6 15.7 8.6
9000 26.4 79.5 275 11 6 8.1 4.5 | 24.4 75.9 290 9 5 7.0 3.8
8750 M M M M M M M | M M M M M M M
8500 M M M M M M M | M M M M M M M
8250 M M M M M M M | M M M M M M M
8000 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 VILLA GROVE, COLORADO AT:
NORTH LATITUDE: 38 DEG 16 MIN 03 SEC
WEST LONGITUDE: 105 DEG 53 MIN 37 SEC
ELEVATION: 7986 FEET (2434 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.
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