310
UXUS97 KPUB 041211
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO, COLORADO
0610 MDT FRIDAY, JULY 4, 2025
THIS FORECAST IS FOR VILLA GROVE, CO FOR FRIDAY, JULY 4, 2025:
IF THE TRIGGER TEMPERATURE OF 63.1 F/17.3 C IS REACHED...THEN
THERMAL SOARING INDEX....................... EXCELLENT
MAXIMUM RATE OF LIFT........................ 962 FT/MIN (4.9 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 21761 FT MSL (12773 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 81.0 F/27.7 C
TIME OF TRIGGER TEMPERATURE.................... 0830 MDT
TIME OF OVERDEVELOPMENT........................ NONE
MIDDLE/HIGH CLOUDS DURING SOARING WINDOW....... BROKEN/OVERCAST THIN MIDDLE
SURFACE WINDS DURING SOARING WINDOW............ 20 MPH OR LESS
HEIGHT OF THE -3 THERMAL INDEX................. 18365 FT MSL (9376 FT AGL)
THERMAL SOARING OUTLOOK FOR SATURDAY 07/05..... EXCELLENT
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 05:45:46 / 20:30:29 MDT
TOTAL POSSIBLE SUNSHINE........... 14 HR 44 MIN 43 SEC (884 MIN 43 SEC)
ALTITUDE OF SUN AT 13:08:08 MDT... 74.43 DEGREES
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 07/04/2025 AT 0600 MDT
FREEZING LEVEL.................. 15405 FT MSL (6417 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 15238 FT MSL (6250 FT AGL)
LIFTED CONDENSATION LEVEL....... 18533 FT MSL (9544 FT AGL)
LIFTED INDEX.................... -4.8
K INDEX......................... +9.2
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 -63.4 -82.1 220 25 13 3.4 1.8 M M M M M
45000 -57.0 -70.6 225 32 17 5.9 3.2 M M M M M
40000 -48.1 -54.6 215 42 22 6.0 3.3 M M M M M
38000 -44.5 -48.1 225 41 21 6.0 3.3 M M M M M
36000 -40.9 -41.6 235 41 21 6.0 3.3 M M M M M
34000 -37.0 -34.6 235 39 20 6.5 3.6 M M M M M
32000 -32.6 -26.7 230 36 19 6.6 3.6 M M M M M
30000 -28.3 -18.9 225 33 17 7.2 3.9 36.1 97.0 7.1 M M
29000 -26.2 -15.2 220 31 16 7.2 3.9 35.2 95.4 6.4 M M
28000 -24.0 -11.2 215 29 15 7.0 3.8 34.4 93.9 5.8 M M
27000 -22.0 -7.6 215 27 14 6.9 3.8 33.2 91.8 4.9 M M
26000 -19.9 -3.8 215 25 13 6.9 3.8 32.2 89.9 4.1 M M
25000 -17.9 -0.2 215 23 12 7.0 3.8 31.2 88.2 3.3 M M
24000 -16.0 3.2 215 21 11 6.3 3.5 30.0 86.0 2.3 M M
23000 -14.1 6.6 215 19 10 6.3 3.5 28.8 83.8 1.2 M M
22000 -12.2 10.0 215 17 9 6.4 3.5 27.7 81.9 0.2 M M
21000 -10.0 14.0 215 16 8 7.5 4.1 26.8 80.2 -0.5 1093 5.6
20000 -7.8 18.0 220 15 7 7.5 4.1 26.0 78.8 -1.2 996 5.1
19500 -6.6 20.1 220 14 7 7.6 4.2 25.7 78.2 -1.5 947 4.8
19000 -5.6 21.9 220 14 7 5.8 3.2 25.2 77.4 -1.9 901 4.6
18500 -4.8 23.4 225 14 7 5.5 3.0 24.5 76.1 -2.7 864 4.4
18000 -4.1 24.6 230 14 7 5.4 3.0 23.8 74.9 -3.4 826 4.2
17500 -3.6 25.5 240 14 7 3.7 2.0 22.9 73.2 -4.3 795 4.0
17000 -3.1 26.4 245 13 7 4.0 2.2 21.9 71.5 -5.4 767 3.9
16500 -2.1 28.2 255 12 6 7.1 3.9 20.9 69.6 -6.6 714 3.6
16000 -1.1 30.0 255 12 6 6.8 3.7 20.5 68.8 -7.1 670 3.4
15500 0.0 32.0 260 12 6 9.2 5.0 20.2 68.3 -7.5 621 3.2
15000 1.4 34.5 260 11 6 9.5 5.2 20.1 68.1 -7.7 566 2.9
14500 2.6 36.7 265 11 6 6.6 3.6 19.8 67.7 -8.0 516 2.6
14000 3.6 38.5 270 13 6 6.9 3.8 19.4 66.8 -8.5 470 2.4
13500 4.6 40.3 275 14 7 6.1 3.3 18.9 66.1 -8.9 425 2.2
13000 5.4 41.7 285 16 8 6.1 3.4 18.3 64.9 -9.6 385 2.0
12500 6.3 43.3 290 18 9 5.9 3.3 17.7 63.9 -10.2 344 1.7
12000 7.2 45.0 290 20 10 5.3 2.9 17.1 62.8 -10.9 304 1.5
11750 7.5 45.5 290 21 11 4.7 2.6 16.7 62.1 -11.3 286 1.5
11500 7.8 46.0 290 22 11 4.8 2.6 16.3 61.4 -11.8 269 1.4
11250 8.1 46.6 290 22 11 4.5 2.5 15.9 60.7 -12.2 252 1.3
11000 8.4 47.1 290 22 11 4.5 2.5 15.5 60.0 -12.7 236 1.2
10750 8.8 47.8 290 22 11 4.2 2.3 15.1 59.2 -13.1 219 1.1
10500 9.0 48.2 290 22 11 3.8 2.1 14.7 58.4 -13.6 205 1.0
10250 9.2 48.6 290 22 11 4.3 2.3 14.2 57.6 -14.2 190 1.0
10000 9.5 49.1 285 20 10 4.2 2.3 13.8 56.9 -14.7 175 0.9
9750 9.7 49.5 285 19 10 5.2 2.9 13.4 56.2 -15.2 160 0.8
9500 10.1 50.2 280 17 9 5.7 3.2 13.1 55.6 -15.6 141 0.7
9250 10.4 50.7 275 13 7 0.9 0.5 12.7 54.8 -16.1 126 0.6
9000 10.1 50.2 265 8 4 -7.0 -3.8 11.7 53.1 -17.1 126 0.6
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 * * * * * *
07/04/2025 AT 0900 MDT | 07/04/2025 AT 1200 MDT
|
CAPE... +144.9 LI... -1.3 | CAPE... +202.1 LI... -2.1
CINH... -16.8 K INDEX... +11.6 | CINH... -12.1 K INDEX... +19.4
|
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 -63.7 -82.7 230 26 13 2.9 1.6 | -63.6 -82.5 225 24 13 2.9 1.6
45000 -57.4 -71.3 230 36 19 6.5 3.6 | -57.4 -71.3 230 35 18 6.3 3.5
40000 -47.8 -54.0 225 44 23 5.8 3.2 | -47.9 -54.2 230 42 22 6.3 3.5
38000 -44.3 -47.7 230 42 21 5.8 3.2 | -44.1 -47.4 235 43 22 6.3 3.5
36000 -40.8 -41.4 235 39 20 5.7 3.1 | -40.3 -40.5 240 43 22 6.4 3.5
34000 -37.0 -34.6 235 37 19 6.4 3.5 | -36.3 -33.3 240 39 20 5.8 3.2
32000 -32.6 -26.7 235 34 17 6.4 3.5 | -32.8 -27.0 240 34 18 5.8 3.2
30000 -27.9 -18.2 240 31 16 8.0 4.4 | -28.6 -19.5 240 32 16 7.1 3.9
29000 -25.5 -13.9 240 30 16 8.0 4.4 | -26.5 -15.7 240 31 16 7.1 3.9
28000 -23.2 -9.8 240 29 15 6.5 3.5 | -24.3 -11.7 245 29 15 8.1 4.4
27000 -21.4 -6.5 240 27 14 5.9 3.3 | -21.8 -7.2 250 28 14 8.3 4.5
26000 -19.6 -3.3 235 26 13 5.9 3.3 | -19.3 -2.7 255 26 13 8.3 4.5
25000 -17.9 -0.2 235 24 12 6.0 3.3 | -16.8 1.8 265 25 13 7.8 4.3
24000 -16.2 2.8 230 22 11 5.7 3.1 | -15.5 4.1 265 23 12 3.5 1.9
23000 -14.5 5.9 230 20 10 5.8 3.2 | -14.5 5.9 265 21 11 3.6 2.0
22000 -12.8 9.0 225 18 9 5.9 3.2 | -13.4 7.9 260 20 10 4.3 2.4
21000 -11.0 12.2 230 16 8 6.1 3.4 | -11.6 11.1 265 18 9 6.8 3.8
20000 -9.2 15.4 235 15 8 6.1 3.4 | -9.6 14.7 270 17 9 7.0 3.8
19500 -8.2 17.2 235 15 7 6.1 3.4 | -8.7 16.3 275 17 9 7.1 3.9
19000 -7.4 18.7 240 14 7 6.1 3.3 | -7.6 18.3 275 16 8 7.5 4.1
18500 -6.5 20.3 250 13 7 6.2 3.4 | -6.6 20.1 280 15 8 7.5 4.1
18000 -5.7 21.7 260 12 6 6.5 3.6 | -5.5 22.1 285 15 7 7.7 4.2
17500 -4.7 23.5 265 12 6 7.4 4.1 | -4.3 24.3 285 14 7 8.1 4.4
17000 -3.7 25.3 270 11 6 7.5 4.1 | -3.2 26.2 290 13 7 8.1 4.4
16500 -2.6 27.3 280 11 6 8.2 4.5 | -1.4 29.5 295 12 6 7.6 4.2
16000 -0.8 30.6 290 12 6 8.4 4.6 | -0.3 31.5 295 12 6 7.6 4.2
15500 0.4 32.7 295 13 6 7.4 4.1 | 0.8 33.4 300 11 6 7.2 3.9
15000 1.5 34.7 300 14 7 7.6 4.2 | 1.8 35.2 300 11 5 7.2 3.9
14500 2.5 36.5 300 15 8 6.2 3.4 | 2.9 37.2 300 12 6 6.5 3.5
14000 3.4 38.1 305 17 9 6.3 3.5 | 3.7 38.7 300 16 8 5.8 3.2
13500 4.3 39.7 305 20 10 7.0 3.9 | 4.6 40.3 305 20 10 6.0 3.3
13000 5.1 41.2 305 22 11 4.1 2.2 | 5.4 41.7 300 21 11 7.3 4.0
12500 5.7 42.3 305 24 12 4.4 2.4 | 6.4 43.5 295 21 11 8.2 4.5
12000 6.3 43.3 300 25 13 4.3 2.4 | 7.7 45.9 290 19 10 9.8 5.4
11750 6.6 43.9 300 24 12 3.9 2.2 | 8.5 47.3 290 19 10 10.2 5.6
11500 6.9 44.4 300 24 12 4.6 2.5 | 9.2 48.6 290 18 10 10.0 5.5
11250 7.2 45.0 295 23 12 6.1 3.3 | 9.9 49.8 290 18 9 9.8 5.4
11000 7.6 45.7 295 21 11 6.1 3.3 | 10.7 51.3 290 18 9 9.7 5.3
10750 8.0 46.4 290 20 10 7.7 4.2 | 11.4 52.5 290 18 9 10.3 5.6
10500 8.7 47.7 290 19 10 10.0 5.5 | 12.2 54.0 290 17 9 11.1 6.1
10250 9.4 48.9 285 18 9 10.5 5.8 | 13.0 55.4 290 17 9 11.2 6.1
10000 10.2 50.4 285 17 9 11.2 6.2 | 13.9 57.0 290 17 9 11.9 6.6
9750 11.0 51.8 285 16 8 9.9 5.4 | 14.7 58.5 290 16 8 9.5 5.2
9500 11.8 53.2 285 15 8 13.9 7.6 | 15.5 59.9 290 16 8 16.2 8.9
9250 13.2 55.8 285 14 7 25.5 14.0 | 17.5 63.5 290 14 7 36.7 20.2
9000 15.0 59.0 285 12 6 15.2 8.4 | 19.9 67.8 290 13 7 16.4 9.0
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
07/04/2025 AT 1500 MDT | 07/04/2025 AT 1800 MDT
|
CAPE... +416.4 LI... -2.1 | CAPE... +296.4 LI... -1.1
CINH... -0.5 K INDEX... +22.9 | CINH... -2.8 K INDEX... +10.5
|
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 -63.5 -82.3 215 26 14 2.4 1.3 | -63.9 -83.0 215 29 15 2.6 1.4
45000 -57.9 -72.2 220 39 20 6.3 3.4 | -58.0 -72.4 225 41 21 6.4 3.5
40000 -48.0 -54.4 230 49 25 6.5 3.5 | -48.0 -54.4 240 51 26 6.6 3.6
38000 -44.1 -47.4 235 50 26 6.5 3.5 | -44.0 -47.2 245 53 27 6.6 3.6
36000 -40.2 -40.4 240 52 27 6.3 3.4 | -40.1 -40.2 250 55 28 6.2 3.4
34000 -36.9 -34.4 240 45 23 5.6 3.1 | -37.0 -34.6 250 48 25 5.0 2.7
32000 -33.5 -28.3 240 37 19 5.5 3.0 | -34.0 -29.2 250 40 21 4.8 2.6
30000 -29.5 -21.1 245 31 16 7.0 3.8 | -29.9 -21.8 250 34 18 7.2 4.0
29000 -27.4 -17.3 245 28 15 7.0 3.8 | -27.7 -17.9 250 31 16 7.2 4.0
28000 -24.8 -12.6 250 25 13 6.9 3.8 | -25.1 -13.2 255 29 15 6.7 3.7
27000 -22.7 -8.9 255 25 13 6.9 3.8 | -23.0 -9.4 260 28 15 6.8 3.7
26000 -20.6 -5.1 265 24 13 6.9 3.8 | -21.0 -5.8 265 28 15 6.8 3.7
25000 -18.5 -1.3 270 24 13 6.9 3.8 | -19.0 -2.2 270 29 15 7.1 3.9
24000 -16.5 2.3 275 23 12 6.8 3.7 | -16.8 1.8 270 26 13 7.3 4.0
23000 -14.5 5.9 285 23 12 6.8 3.8 | -14.6 5.7 275 24 12 7.3 4.0
22000 -12.5 9.5 295 23 12 6.7 3.7 | -12.4 9.7 280 21 11 7.1 3.9
21000 -10.6 12.9 290 21 11 6.5 3.6 | -10.4 13.3 280 20 10 7.0 3.8
20000 -8.7 16.3 290 19 10 6.8 3.7 | -8.3 17.1 285 18 9 7.0 3.8
19500 -7.8 18.0 290 18 9 6.9 3.8 | -7.3 18.9 285 17 9 7.0 3.9
19000 -6.8 19.8 285 16 8 7.6 4.2 | -6.2 20.8 285 16 8 7.6 4.2
18500 -5.7 21.7 285 15 7 7.6 4.2 | -5.1 22.8 280 15 8 7.7 4.2
18000 -4.6 23.7 285 13 7 7.7 4.2 | -4.0 24.8 280 15 8 7.8 4.3
17500 -3.5 25.7 285 13 7 7.9 4.3 | -3.0 26.6 280 14 7 7.9 4.3
17000 -2.3 27.9 290 13 7 7.9 4.4 | -1.9 28.6 285 13 7 8.2 4.5
16500 -1.2 29.8 290 14 7 7.2 4.0 | -0.7 30.7 285 13 7 9.1 5.0
16000 -0.2 31.6 295 15 8 7.3 4.0 | 0.6 33.1 290 13 7 9.1 5.0
15500 0.9 33.6 300 16 8 8.1 4.4 | 1.8 35.2 290 12 6 9.5 5.2
15000 2.6 36.7 300 17 9 8.2 4.5 | 3.2 37.8 295 12 6 9.5 5.2
14500 3.9 39.0 300 17 9 10.1 5.5 | 5.3 41.5 295 12 6 9.6 5.3
14000 5.3 41.5 300 17 9 9.4 5.2 | 6.8 44.2 295 12 6 10.0 5.5
13500 6.7 44.1 300 17 9 10.4 5.7 | 8.1 46.6 295 12 6 8.7 4.8
13000 8.1 46.6 300 17 9 9.4 5.2 | 9.5 49.1 295 12 6 10.3 5.6
12500 9.6 49.3 300 17 9 9.8 5.4 | 11.0 51.8 295 11 6 10.3 5.7
12000 11.1 52.0 300 16 8 10.2 5.6 | 12.6 54.7 295 11 6 10.1 5.5
11750 11.8 53.2 300 16 8 10.3 5.6 | 13.3 55.9 295 11 6 10.0 5.5
11500 12.6 54.7 300 16 8 10.0 5.5 | 14.1 57.4 295 11 6 9.5 5.2
11250 13.3 55.9 300 16 8 9.6 5.2 | 14.7 58.5 295 11 6 8.9 4.9
11000 14.0 57.2 300 16 8 9.6 5.3 | 15.4 59.7 295 11 6 9.0 4.9
10750 14.8 58.6 300 16 8 10.3 5.6 | 16.1 61.0 295 11 6 10.1 5.5
10500 15.6 60.1 300 16 8 11.0 6.0 | 16.9 62.4 295 11 6 10.8 5.9
10250 16.4 61.5 300 15 8 10.8 5.9 | 17.7 63.9 295 11 5 10.5 5.7
10000 17.2 63.0 300 15 8 11.4 6.3 | 18.5 65.3 295 10 5 10.8 5.9
9750 18.0 64.4 300 15 8 9.4 5.1 | 19.3 66.7 300 10 5 9.8 5.4
9500 18.8 65.8 300 14 7 15.9 8.7 | 20.0 68.0 300 10 5 13.4 7.4
9250 20.7 69.3 300 14 7 35.4 19.4 | 21.4 70.5 295 9 5 23.0 12.6
9000 23.1 73.6 300 13 6 18.2 10.0 | 22.9 73.2 295 9 4 11.9 6.5
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
________________________________________________________________________________
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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