704
UXUS97 KPUB 231216
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO, COLORADO
0615 MDT THURSDAY, OCTOBER 23, 2025
THIS FORECAST IS FOR VILLA GROVE, CO FOR THURSDAY, OCTOBER 23, 2025:
IF THE TRIGGER TEMPERATURE OF 53.4 F/11.9 C IS REACHED...THEN
THERMAL SOARING INDEX....................... GOOD
MAXIMUM RATE OF LIFT........................ 558 FT/MIN (2.8 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 16927 FT MSL (7958 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 60.0 F/16.0 C
TIME OF TRIGGER TEMPERATURE.................... 1115 MDT
TIME OF OVERDEVELOPMENT........................ 1600 MDT
MIDDLE/HIGH CLOUDS DURING SOARING WINDOW....... OVERCAST OPAQUE HIGH
SURFACE WINDS DURING SOARING WINDOW............ 20 MPH OR LESS
HEIGHT OF THE -3 THERMAL INDEX................. 13530 FT MSL (4562 FT AGL)
THERMAL SOARING OUTLOOK FOR FRIDAY 10/24....... EXCELLENT
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 07:20:59 / 18:14:36 MDT
TOTAL POSSIBLE SUNSHINE........... 10 HR 53 MIN 37 SEC (653 MIN 37 SEC)
ALTITUDE OF SUN AT 12:47:47 MDT... 39.96 DEGREES
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 10/23/2025 AT 0600 MDT
FREEZING LEVEL.................. 12963 FT MSL (3994 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 16232 FT MSL (7263 FT AGL)
LIFTED CONDENSATION LEVEL....... 16648 FT MSL (7680 FT AGL)
LIFTED INDEX.................... -0.5
K INDEX......................... +9.9
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 -63.7 -82.7 260 40 21 0.8 0.5 M M M M M
45000 -62.3 -80.1 255 45 23 1.7 0.9 M M M M M
40000 -59.7 -75.5 245 59 30 1.2 0.7 M M M M M
38000 -56.7 -70.1 240 56 29 5.5 3.0 M M M M M
36000 -53.5 -64.3 240 51 26 5.5 3.0 M M M M M
34000 -49.4 -56.9 240 49 25 8.1 4.4 M M M M M
32000 -44.5 -48.1 240 47 24 8.1 4.4 M M M M M
30000 -39.3 -38.7 240 46 24 9.3 5.1 24.9 76.8 7.3 M M
29000 -36.5 -33.7 240 45 23 9.3 5.1 24.7 76.4 7.2 M M
28000 -33.0 -27.4 240 44 22 9.4 5.2 24.6 76.3 7.3 M M
27000 -30.5 -22.9 245 42 22 8.1 4.4 24.1 75.3 6.9 M M
26000 -28.1 -18.6 245 41 21 8.1 4.4 23.4 74.1 6.5 M M
25000 -25.7 -14.3 245 39 20 8.0 4.4 22.9 73.1 6.1 M M
24000 -23.3 -9.9 250 37 19 7.8 4.3 22.2 72.0 5.6 M M
23000 -21.0 -5.8 250 34 17 7.8 4.3 21.5 70.7 5.1 M M
22000 -18.6 -1.5 255 31 16 7.8 4.3 20.9 69.6 4.6 M M
21000 -16.3 2.7 255 28 14 7.7 4.2 20.2 68.4 4.0 M M
20000 -14.1 6.6 250 24 12 7.8 4.3 19.5 67.1 3.4 M M
19500 -12.9 8.8 245 22 11 7.8 4.3 19.2 66.5 3.1 M M
19000 -11.8 10.8 245 21 11 7.1 3.9 18.9 66.0 2.8 M M
18500 -10.9 12.4 240 20 10 5.2 2.8 18.2 64.8 2.2 M M
18000 -10.2 13.6 240 20 10 5.2 2.9 17.5 63.5 1.5 M M
17500 -9.4 15.1 240 20 10 5.4 2.9 16.7 62.1 0.9 M M
17000 -8.6 16.5 240 20 10 5.4 3.0 16.0 60.8 0.2 M M
16500 -7.8 18.0 240 19 10 6.1 3.3 15.3 59.6 -0.5 732 3.7
16000 -6.8 19.8 245 20 10 7.0 3.9 14.8 58.7 -0.9 686 3.5
15500 -5.8 21.6 245 21 11 7.1 3.9 14.4 58.0 -1.3 641 3.3
15000 -4.7 23.5 245 22 11 7.9 4.3 14.1 57.3 -1.7 593 3.0
14500 -3.6 25.5 245 23 12 8.1 4.4 13.7 56.7 -2.1 545 2.8
14000 -2.0 28.4 245 26 13 8.2 4.5 13.2 55.7 -2.7 476 2.4
13500 -0.9 30.4 240 27 14 7.6 4.2 12.9 55.2 -3.1 428 2.2
13000 0.1 32.2 240 27 14 8.2 4.5 12.6 54.6 -3.5 382 1.9
12500 1.3 34.3 240 27 14 8.5 4.7 12.4 54.2 -3.9 333 1.7
12000 2.5 36.5 240 26 14 8.7 4.8 12.1 53.9 -4.1 282 1.4
11750 3.2 37.8 240 26 13 9.4 5.1 12.1 53.8 -4.2 254 1.3
11500 3.9 39.0 240 25 13 9.8 5.3 12.1 53.7 -4.2 226 1.1
11250 4.6 40.3 240 25 13 7.2 4.0 12.0 53.7 -4.3 198 1.0
11000 5.0 41.0 240 24 12 5.3 2.9 11.7 53.1 -4.6 177 0.9
10750 5.5 41.9 240 22 11 5.3 2.9 11.4 52.5 -4.8 156 0.8
10500 5.9 42.6 240 21 11 5.2 2.8 11.0 51.9 -5.2 136 0.7
10250 6.2 43.2 240 19 10 -0.8 -0.4 10.6 51.0 -5.6 119 0.6
10000 5.9 42.6 240 17 9 -6.2 -3.4 9.4 49.0 -6.7 122 0.6
9750 5.5 41.9 240 15 8 -3.8 -2.1 8.3 47.0 -7.8 125 0.6
9500 5.2 41.4 235 13 7 -7.1 -3.9 7.3 45.1 -8.9 128 0.7
9250 4.1 39.4 235 10 5 -22.7 -12.5 5.5 41.9 -10.6 152 0.8
9000 1.4 34.5 230 5 3 -53.8 -29.5 2.0 35.6 -14.1 227 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 * * * * * *
10/23/2025 AT 0900 MDT | 10/23/2025 AT 1200 MDT
|
CAPE... 0.0 LI... +0.8 | CAPE... +72.9 LI... -0.2
CINH... 0.0 K INDEX... -2.7 | CINH... -12.4 K INDEX... +15.7
|
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 -61.9 -79.4 260 38 19 0.4 0.2 | -61.2 -78.2 265 31 16 1.1 0.6
45000 -61.2 -78.2 245 45 23 1.3 0.7 | -59.5 -75.1 250 41 21 0.6 0.3
40000 -59.1 -74.4 235 53 27 1.1 0.6 | -58.5 -73.3 225 49 25 0.6 0.3
38000 -56.6 -69.9 230 50 26 4.7 2.6 | -56.5 -69.7 220 49 25 4.2 2.3
36000 -53.8 -64.8 230 46 23 4.7 2.6 | -54.0 -65.2 220 49 25 4.2 2.3
34000 -49.9 -57.8 230 44 23 8.5 4.6 | -50.3 -58.5 220 49 25 8.5 4.6
32000 -44.9 -48.8 230 46 23 8.5 4.6 | -45.3 -49.5 220 49 25 8.5 4.6
30000 -39.7 -39.5 230 45 23 8.8 4.8 | -40.2 -40.4 220 48 25 8.6 4.7
29000 -36.4 -33.5 230 43 22 8.8 4.8 | -36.9 -34.4 220 46 24 8.6 4.7
28000 -33.7 -28.7 235 42 21 8.9 4.9 | -34.4 -29.9 225 44 23 8.6 4.7
27000 -31.2 -24.2 235 40 21 8.1 4.5 | -31.9 -25.4 225 42 21 8.2 4.5
26000 -28.8 -19.8 235 38 20 8.1 4.5 | -29.4 -20.9 225 38 20 8.2 4.5
25000 -26.4 -15.5 240 36 19 8.1 4.5 | -27.0 -16.6 225 35 18 8.2 4.5
24000 -23.9 -11.0 240 33 17 7.9 4.4 | -24.5 -12.1 225 31 16 7.7 4.2
23000 -21.6 -6.9 240 30 15 7.9 4.4 | -22.2 -8.0 225 29 15 7.8 4.3
22000 -19.2 -2.6 240 26 14 7.9 4.4 | -19.9 -3.8 225 26 14 7.7 4.2
21000 -16.9 1.6 240 24 12 7.6 4.1 | -17.7 0.1 225 25 13 7.3 4.0
20000 -14.6 5.7 240 22 11 7.5 4.1 | -15.5 4.1 230 25 13 7.3 4.0
19500 -13.5 7.7 240 21 11 7.5 4.1 | -14.5 5.9 230 24 13 7.3 4.0
19000 -12.4 9.7 240 21 11 7.5 4.1 | -13.4 7.9 230 24 13 7.2 4.0
18500 -11.3 11.7 240 22 11 7.4 4.0 | -12.5 9.5 230 25 13 6.1 3.3
18000 -10.2 13.6 240 23 12 7.4 4.1 | -11.6 11.1 235 26 13 6.2 3.4
17500 -9.1 15.6 245 24 12 6.6 3.6 | -10.7 12.7 235 27 14 6.3 3.5
17000 -8.2 17.2 245 25 13 6.5 3.6 | -9.8 14.4 235 28 14 6.4 3.5
16500 -7.2 19.0 245 27 14 6.4 3.5 | -8.9 16.0 235 29 15 6.6 3.6
16000 -6.3 20.7 245 29 15 6.3 3.4 | -7.9 17.8 235 29 15 7.1 3.9
15500 -5.5 22.1 245 31 16 6.5 3.6 | -6.9 19.6 235 29 15 7.1 3.9
15000 -4.6 23.7 245 32 16 6.8 3.7 | -5.8 21.6 235 28 15 8.0 4.4
14500 -3.6 25.5 245 33 17 7.1 3.9 | -4.7 23.5 235 27 14 8.1 4.4
14000 -2.2 28.0 245 33 17 7.6 4.1 | -3.0 26.6 235 25 13 8.2 4.5
13500 -1.2 29.8 245 32 17 7.0 3.8 | -1.8 28.8 235 23 12 7.6 4.2
13000 -0.2 31.6 245 29 15 7.4 4.1 | -0.8 30.6 235 20 10 7.9 4.3
12500 0.9 33.6 250 24 12 8.0 4.4 | 0.4 32.7 240 19 10 8.6 4.7
12000 1.7 35.1 250 21 11 5.8 3.2 | 1.4 34.5 240 16 8 6.1 3.3
11750 2.3 36.1 250 21 11 8.5 4.7 | 2.0 35.6 240 15 8 8.5 4.7
11500 2.9 37.2 250 20 10 8.9 4.9 | 2.6 36.7 235 13 7 8.7 4.8
11250 3.5 38.3 245 20 10 7.5 4.1 | 3.2 37.8 235 12 6 7.9 4.3
11000 4.0 39.2 245 20 10 6.5 3.6 | 3.7 38.7 230 11 5 6.7 3.7
10750 4.5 40.1 245 19 10 6.0 3.3 | 4.3 39.7 225 10 5 8.3 4.6
10500 4.9 40.8 245 19 10 5.6 3.1 | 5.0 41.0 225 9 5 9.7 5.3
10250 5.2 41.4 240 18 9 1.0 0.6 | 5.7 42.3 220 9 5 9.6 5.3
10000 5.1 41.2 240 17 9 -2.9 -1.6 | 6.4 43.5 220 8 4 9.9 5.4
9750 5.0 41.0 240 15 8 -2.1 -1.2 | 7.2 45.0 220 8 4 9.7 5.3
9500 4.9 40.8 240 13 7 -2.8 -1.6 | 7.9 46.2 215 8 4 11.4 6.2
9250 4.8 40.6 235 10 5 0.6 0.3 | 9.0 48.2 215 7 4 19.5 10.7
9000 5.2 41.4 230 5 3 10.8 5.9 | 11.1 52.0 215 7 4 38.9 21.4
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
10/23/2025 AT 1500 MDT | 10/23/2025 AT 1800 MDT
|
CAPE... +398.2 LI... -1.4 | CAPE... +485.1 LI... -2.3
CINH... -1.2 K INDEX... +11.6 | CINH... -8.4 K INDEX... +9.4
|
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 -60.8 -77.4 260 29 15 2.0 1.1 | -60.8 -77.4 265 27 14 2.0 1.1
45000 -58.0 -72.4 255 37 19 0.5 0.3 | -57.9 -72.2 265 34 17 1.7 0.9
40000 -57.3 -71.1 235 48 25 0.5 0.3 | -55.2 -67.4 240 38 20 1.8 1.0
38000 -55.3 -67.5 225 50 26 4.2 2.3 | -53.4 -64.1 230 42 22 3.4 1.8
36000 -52.8 -63.0 220 52 27 4.2 2.3 | -51.4 -60.5 225 47 24 3.4 1.8
34000 -49.6 -57.3 215 54 28 7.4 4.1 | -48.9 -56.0 225 51 26 5.6 3.1
32000 -45.1 -49.2 215 53 27 7.4 4.1 | -45.6 -50.1 220 53 27 5.6 3.1
30000 -40.7 -41.3 215 51 26 7.5 4.1 | -41.8 -43.2 220 52 27 7.7 4.2
29000 -37.9 -36.2 215 49 25 7.5 4.1 | -39.5 -39.1 220 49 25 7.7 4.2
28000 -35.6 -32.1 215 47 24 7.5 4.1 | -36.6 -33.9 220 44 23 7.7 4.2
27000 -33.3 -27.9 215 45 23 8.2 4.5 | -34.3 -29.7 225 41 21 7.6 4.2
26000 -30.8 -23.4 215 44 22 8.3 4.5 | -32.0 -25.6 225 38 19 7.6 4.2
25000 -28.3 -18.9 215 42 22 8.3 4.5 | -29.8 -21.6 230 35 18 7.6 4.2
24000 -25.9 -14.6 215 40 20 7.5 4.1 | -27.5 -17.5 235 32 16 7.5 4.1
23000 -23.7 -10.7 215 37 19 7.5 4.1 | -25.2 -13.4 235 28 14 7.5 4.1
22000 -21.4 -6.5 215 34 17 7.6 4.2 | -23.0 -9.4 235 23 12 7.6 4.2
21000 -19.1 -2.4 215 31 16 8.0 4.4 | -20.6 -5.1 240 20 10 8.9 4.9
20000 -16.7 1.9 215 28 14 8.0 4.4 | -17.9 -0.2 235 18 9 8.9 4.9
19500 -15.5 4.1 220 27 14 8.0 4.4 | -16.6 2.1 235 17 9 8.9 4.9
19000 -14.3 6.3 220 26 13 8.0 4.4 | -15.2 4.6 230 16 8 8.9 4.9
18500 -13.2 8.2 220 25 13 7.5 4.1 | -13.9 7.0 230 15 8 8.5 4.6
18000 -12.1 10.2 215 24 12 7.6 4.2 | -12.6 9.3 225 15 8 8.5 4.7
17500 -11.0 12.2 215 23 12 7.2 3.9 | -11.4 11.5 220 15 7 7.7 4.2
17000 -10.0 14.0 215 23 12 7.0 3.8 | -10.3 13.5 220 14 7 7.3 4.0
16500 -9.0 15.8 215 23 12 7.0 3.9 | -9.3 15.3 215 14 7 7.3 4.0
16000 -7.9 17.8 215 23 12 7.2 4.0 | -8.1 17.4 215 14 7 7.9 4.3
15500 -6.9 19.6 215 23 12 7.1 3.9 | -7.0 19.4 210 15 8 7.9 4.3
15000 -5.8 21.6 210 23 12 8.8 4.8 | -5.8 21.6 205 15 8 8.8 4.8
14500 -3.9 25.0 210 23 12 6.6 3.6 | -4.6 23.7 200 15 8 9.4 5.1
14000 -2.9 26.8 210 23 12 9.0 4.9 | -3.7 25.3 195 15 8 6.1 3.4
13500 -1.7 28.9 210 22 11 8.5 4.7 | -1.9 28.6 190 14 7 8.8 4.8
13000 -0.6 30.9 205 21 11 7.8 4.3 | -0.7 30.7 190 14 7 8.1 4.5
12500 0.6 33.1 200 19 10 8.3 4.5 | 0.5 32.9 190 14 7 9.1 5.0
12000 1.7 35.1 195 17 9 8.1 4.4 | 1.7 35.1 190 13 7 8.1 4.5
11750 2.4 36.3 195 17 9 9.9 5.5 | 2.4 36.3 190 12 6 9.1 5.0
11500 3.1 37.6 195 17 8 9.9 5.4 | 3.0 37.4 185 12 6 9.1 5.0
11250 3.8 38.8 190 16 8 9.6 5.3 | 3.7 38.7 185 11 6 8.9 4.9
11000 4.5 40.1 190 16 8 8.8 4.8 | 4.3 39.7 185 10 5 8.3 4.5
10750 5.1 41.2 190 16 8 9.9 5.4 | 4.9 40.8 185 10 5 9.0 5.0
10500 6.0 42.8 190 16 8 11.1 6.1 | 5.6 42.1 185 9 5 10.0 5.5
10250 6.8 44.2 190 15 8 10.5 5.8 | 6.3 43.3 185 9 5 9.5 5.2
10000 7.5 45.5 190 15 8 10.0 5.5 | 7.0 44.6 185 8 4 9.1 5.0
9750 8.3 46.9 190 15 8 10.6 5.8 | 7.7 45.9 185 8 4 9.0 4.9
9500 9.1 48.4 190 14 7 10.9 6.0 | 8.4 47.1 185 7 4 10.3 5.6
9250 10.0 50.0 190 13 7 16.7 9.2 | 9.2 48.6 185 6 3 8.9 4.9
9000 12.3 54.1 190 12 6 52.4 28.7 | 9.2 48.6 180 4 2 -12.5 -6.9
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.
042613
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