046
UXUS97 KPUB 281206
SRGPUB
SOARING FORECAST
NATIONAL WEATHER SERVICE PUEBLO, COLORADO
0606 MDT MONDAY, APRIL 28, 2025
THIS FORECAST IS FOR VILLA GROVE, CO FOR MONDAY, APRIL 28, 2025:
IF THE TRIGGER TEMPERATURE OF 36.5 F/2.5 C IS REACHED...THEN
THERMAL SOARING INDEX....................... FAIR
MAXIMUM RATE OF LIFT........................ 1079 FT/MIN (5.5 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 22802 FT MSL (13828 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 55.0 F/13.2 C
TIME OF TRIGGER TEMPERATURE.................... 0830 MDT
TIME OF OVERDEVELOPMENT........................ 1700 MDT
MIDDLE/HIGH CLOUDS DURING SOARING WINDOW....... BROKEN/OVERCAST THIN MIDDLE
SURFACE WINDS DURING SOARING WINDOW............ MORE THAN 30 MPH
HEIGHT OF THE -3 THERMAL INDEX................. 19488 FT MSL (10514 FT AGL)
THERMAL SOARING OUTLOOK FOR TUESDAY 04/29...... FAIR
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 06:09:43 / 19:52:16 MDT
TOTAL POSSIBLE SUNSHINE........... 13 HR 42 MIN 32 SEC (822 MIN 32 SEC)
ALTITUDE OF SUN AT 13:01:00 MDT... 66.14 DEGREES
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 04/28/2025 AT 0600 MDT
FREEZING LEVEL.................. ENTIRE AIRMASS BELOW 32 F / 0 C
CONVECTIVE CONDENSATION LEVEL... 15493 FT MSL (6519 FT AGL)
LIFTED CONDENSATION LEVEL....... 18635 FT MSL (9661 FT AGL)
LIFTED INDEX.................... +1.8
K INDEX......................... -18.2
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 -55.7 -68.3 220 42 22 1.4 0.8 M M M M M
45000 -53.7 -64.7 220 45 23 1.2 0.7 M M M M M
40000 -51.8 -61.2 225 56 29 1.2 0.7 M M M M M
38000 -50.9 -59.6 230 66 34 2.1 1.1 M M M M M
36000 -49.6 -57.3 230 80 41 2.1 1.1 M M M M M
34000 -48.2 -54.8 235 94 48 5.9 3.2 M M M M M
32000 -43.8 -46.8 235 100 52 6.5 3.6 M M M M M
30000 -40.1 -40.2 235 104 54 4.6 2.5 25.5 77.9 9.9 M M
29000 -38.7 -37.7 235 101 52 4.7 2.6 23.5 74.2 8.4 M M
28000 -37.2 -35.0 235 98 51 4.7 2.6 21.6 70.8 7.0 M M
27000 -35.8 -32.4 235 95 49 4.7 2.6 19.8 67.7 5.7 M M
26000 -34.5 -30.1 235 91 47 4.5 2.4 17.8 64.1 4.2 M M
25000 -33.1 -27.6 235 87 45 4.5 2.4 15.9 60.6 2.6 M M
24000 -31.8 -25.2 235 83 43 4.2 2.3 14.1 57.3 1.1 M M
23000 -29.8 -21.6 235 81 42 7.7 4.2 13.0 55.3 0.1 M M
22000 -27.5 -17.5 240 78 40 7.8 4.3 12.2 54.0 -0.5 1202 6.1
21000 -25.1 -13.2 240 76 39 7.4 4.0 11.6 52.9 -1.0 1103 5.6
20000 -23.4 -10.1 240 70 36 5.6 3.1 10.2 50.4 -2.3 1020 5.2
19500 -22.5 -8.5 240 66 34 5.6 3.1 9.5 49.2 -2.9 979 5.0
19000 -21.7 -7.1 240 63 32 5.6 3.1 8.9 47.9 -3.5 939 4.8
18500 -20.8 -5.4 240 60 31 5.6 3.1 8.2 46.8 -4.1 899 4.6
18000 -20.0 -4.0 240 56 29 5.9 3.2 7.6 45.6 -4.7 858 4.4
17500 -19.1 -2.4 245 52 27 5.9 3.2 6.9 44.4 -5.4 817 4.2
17000 -18.2 -0.8 245 47 24 7.1 3.9 6.4 43.4 -5.9 775 3.9
16500 -17.0 1.4 245 42 21 7.5 4.1 6.0 42.8 -6.3 726 3.7
16000 -15.9 3.4 250 36 19 7.5 4.1 5.6 42.1 -6.7 678 3.4
15500 -14.3 6.3 250 30 15 7.3 4.0 5.0 41.0 -7.3 607 3.1
15000 -13.2 8.2 250 26 14 7.8 4.3 4.7 40.4 -7.7 559 2.8
14500 -12.0 10.4 255 29 15 7.6 4.2 4.4 39.9 -8.0 509 2.6
14000 -11.2 11.8 255 31 16 5.2 2.8 3.7 38.6 -8.8 470 2.4
13500 -10.2 13.6 255 31 16 6.8 3.7 3.2 37.7 -9.3 427 2.2
13000 -9.3 15.3 260 32 16 6.3 3.5 2.6 36.8 -9.9 385 2.0
12500 -8.2 17.2 260 30 15 8.3 4.5 2.3 36.2 -10.3 336 1.7
12000 -7.0 19.4 260 28 15 8.0 4.4 2.1 35.8 -10.7 286 1.5
11750 -6.4 20.5 260 27 14 8.9 4.9 2.0 35.5 -10.8 261 1.3
11500 -5.7 21.7 260 26 14 9.9 5.4 2.0 35.5 -10.9 232 1.2
11250 -5.0 23.0 260 25 13 9.7 5.3 2.0 35.5 -11.0 204 1.0
11000 -4.3 24.3 260 24 13 9.5 5.2 2.0 35.5 -11.0 175 0.9
10750 -3.6 25.5 260 24 12 9.2 5.1 1.9 35.5 -11.1 147 0.7
10500 -3.0 26.6 260 22 11 8.9 4.9 1.9 35.4 -11.2 120 0.6
10250 -2.3 27.9 255 21 11 9.7 5.3 1.8 35.3 -11.3 92 0.5
10000 -1.6 29.1 255 19 10 7.0 3.8 1.8 35.2 -11.4 65 0.3
9750 -1.3 29.7 255 18 9 3.5 1.9 1.4 34.5 -11.8 48 0.2
9500 -1.1 30.0 250 16 8 2.3 1.3 0.9 33.6 -12.3 33 0.2
9250 -1.1 30.0 250 13 7 -6.3 -3.5 0.1 32.1 -13.2 28 0.1
9000 -2.4 27.7 245 7 3 -30.6 -16.8 -1.9 28.6 -15.2 58 0.3
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 * * * * * *
04/28/2025 AT 0900 MDT | 04/28/2025 AT 1200 MDT
|
CAPE... +3.2 LI... +3.0 | CAPE... +22.8 LI... +1.5
CINH... 0.0 K INDEX... -18.3 | CINH... 0.0 K INDEX... -13.1
|
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 -55.0 -67.0 220 39 20 1.2 0.7 | -55.0 -67.0 220 31 16 1.0 0.6
45000 -53.2 -63.8 220 49 25 0.4 0.2 | -53.4 -64.1 225 48 25 0.7 0.4
40000 -52.8 -63.0 225 59 31 0.3 0.2 | -52.6 -62.7 225 59 30 0.5 0.3
38000 -51.9 -61.4 230 66 34 2.8 1.5 | -51.3 -60.3 230 65 33 3.4 1.8
36000 -50.2 -58.4 230 75 39 2.8 1.5 | -49.3 -56.7 230 73 38 3.4 1.8
34000 -48.4 -55.1 235 83 43 5.4 2.9 | -47.2 -53.0 230 81 41 4.5 2.5
32000 -44.6 -48.3 235 88 45 5.7 3.1 | -44.6 -48.3 235 85 44 4.4 2.4
30000 -41.1 -42.0 235 91 47 6.6 3.6 | -41.8 -43.2 235 88 45 6.8 3.7
29000 -39.1 -38.4 235 90 46 6.6 3.6 | -39.8 -39.6 235 87 45 6.6 3.6
28000 -37.1 -34.8 235 89 46 6.6 3.6 | -37.8 -36.0 235 85 44 6.6 3.6
27000 -35.2 -31.4 235 88 45 6.4 3.5 | -35.4 -31.7 230 84 43 6.2 3.4
26000 -33.6 -28.5 235 86 44 4.8 2.6 | -33.8 -28.8 235 81 42 5.2 2.9
25000 -32.2 -26.0 230 83 43 4.8 2.6 | -32.2 -26.0 235 78 40 5.2 2.9
24000 -30.8 -23.4 230 81 42 4.5 2.5 | -30.6 -23.1 235 75 39 5.2 2.9
23000 -28.8 -19.8 235 79 41 7.1 3.9 | -28.9 -20.0 235 72 37 6.0 3.3
22000 -26.7 -16.1 235 77 39 7.1 3.9 | -27.1 -16.8 240 70 36 6.0 3.3
21000 -24.6 -12.3 235 75 38 6.7 3.7 | -25.3 -13.5 245 68 35 5.9 3.2
20000 -22.9 -9.2 240 69 35 5.5 3.0 | -23.6 -10.5 245 58 30 5.8 3.2
19500 -22.1 -7.8 240 65 34 5.5 3.0 | -22.7 -8.9 250 52 27 5.8 3.2
19000 -21.3 -6.3 240 62 32 5.5 3.0 | -21.9 -7.4 255 47 24 5.8 3.2
18500 -20.4 -4.7 245 59 30 5.5 3.0 | -21.0 -5.8 255 43 22 5.7 3.1
18000 -19.6 -3.3 245 55 28 5.2 2.9 | -20.2 -4.4 260 38 20 5.3 2.9
17500 -18.8 -1.8 245 49 25 5.2 2.8 | -19.4 -2.9 265 34 17 5.3 2.9
17000 -18.0 -0.4 245 44 22 5.9 3.2 | -18.6 -1.5 265 31 16 6.2 3.4
16500 -17.1 1.2 250 38 20 6.1 3.3 | -17.6 0.3 270 30 15 6.2 3.4
16000 -15.8 3.6 255 30 16 6.1 3.4 | -16.7 1.9 275 29 15 6.6 3.6
15500 -14.9 5.2 255 26 13 6.2 3.4 | -15.7 3.7 275 27 14 7.1 3.9
15000 -13.9 7.0 260 23 12 6.6 3.6 | -14.7 5.5 275 26 13 8.1 4.5
14500 -12.9 8.8 265 24 12 6.7 3.7 | -13.2 8.2 275 24 13 11.7 6.4
14000 -12.2 10.0 270 25 13 5.1 2.8 | -11.4 11.5 270 23 12 8.2 4.5
13500 -11.3 11.7 270 27 14 6.5 3.6 | -9.9 14.2 270 23 12 10.4 5.7
13000 -10.3 13.5 270 28 15 7.2 3.9 | -8.5 16.7 270 23 12 8.8 4.9
12500 -9.2 15.4 270 27 14 8.1 4.4 | -7.0 19.4 270 23 12 10.1 5.5
12000 -8.0 17.6 270 26 13 8.2 4.5 | -5.5 22.1 270 22 11 9.5 5.2
11750 -7.4 18.7 270 25 13 9.4 5.2 | -4.8 23.4 270 22 11 9.5 5.2
11500 -6.6 20.1 270 24 13 10.3 5.6 | -4.1 24.6 270 22 11 10.4 5.7
11250 -5.9 21.4 270 24 12 10.1 5.6 | -3.3 26.1 270 22 11 10.1 5.6
11000 -5.1 22.8 270 23 12 9.8 5.4 | -2.5 27.5 270 22 11 10.2 5.6
10750 -4.4 24.1 270 23 12 9.8 5.4 | -1.8 28.8 270 21 11 10.5 5.8
10500 -3.7 25.3 270 22 11 10.3 5.7 | -1.0 30.2 270 21 11 10.7 5.9
10250 -2.9 26.8 270 21 11 10.2 5.6 | -0.2 31.6 270 21 11 10.7 5.9
10000 -2.1 28.2 270 21 11 10.9 6.0 | 0.6 33.1 270 20 11 11.0 6.0
9750 -1.3 29.7 270 20 10 12.0 6.6 | 1.5 34.7 270 20 10 12.0 6.6
9500 -0.4 31.3 270 19 10 10.2 5.6 | 2.4 36.3 270 19 10 10.2 5.6
9250 0.4 32.7 270 18 9 15.1 8.3 | 3.3 37.9 270 18 9 18.9 10.4
9000 2.9 37.2 265 14 7 61.3 33.6 | 6.8 44.2 270 15 8 93.1 51.1
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
04/28/2025 AT 1500 MDT | 04/28/2025 AT 1800 MDT
|
CAPE... +69.5 LI... -0.4 | CAPE... +3.3 LI... +0.1
CINH... -0.1 K INDEX... -1.0 | CINH... -1.3 K INDEX... +14.0
|
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 -55.6 -68.1 220 31 16 1.2 0.6 | -55.3 -67.5 225 33 17 0.7 0.4
45000 -53.8 -64.8 230 43 22 1.0 0.6 | -54.2 -65.6 230 42 21 1.6 0.9
40000 -52.3 -62.1 235 52 27 1.0 0.5 | -51.6 -60.9 230 46 24 1.8 1.0
38000 -51.0 -59.8 235 59 30 3.6 2.0 | -50.3 -58.5 230 53 27 2.4 1.3
36000 -48.8 -55.8 230 69 35 3.6 2.0 | -48.9 -56.0 230 64 33 2.4 1.3
34000 -46.4 -51.5 230 79 41 3.5 1.9 | -47.4 -53.3 230 74 38 1.6 0.9
32000 -44.2 -47.6 230 83 43 3.5 1.9 | -46.5 -51.7 230 72 37 1.4 0.8
30000 -42.0 -43.6 230 84 43 4.8 2.7 | -45.3 -49.5 230 68 35 5.0 2.8
29000 -40.6 -41.1 230 80 41 4.8 2.6 | -43.8 -46.8 235 62 32 4.8 2.7
28000 -39.1 -38.4 230 77 39 4.8 2.6 | -42.4 -44.3 235 56 29 4.8 2.7
27000 -37.7 -35.9 235 73 37 4.9 2.7 | -40.9 -41.6 240 50 26 5.7 3.1
26000 -36.0 -32.8 235 68 35 5.8 3.2 | -38.6 -37.5 240 43 22 8.0 4.4
25000 -34.3 -29.7 240 64 33 5.7 3.2 | -36.2 -33.2 240 35 18 8.1 4.4
24000 -32.5 -26.5 240 60 31 5.7 3.1 | -33.8 -28.8 240 28 14 8.1 4.4
23000 -30.8 -23.4 245 55 28 5.9 3.2 | -31.4 -24.5 240 23 12 8.2 4.5
22000 -29.0 -20.2 250 50 26 5.9 3.3 | -28.9 -20.0 245 18 9 8.3 4.5
21000 -27.3 -17.1 255 46 24 6.7 3.7 | -26.4 -15.5 250 14 7 7.8 4.3
20000 -24.9 -12.8 260 40 21 7.8 4.3 | -24.2 -11.6 250 12 6 7.6 4.2
19500 -23.7 -10.7 260 37 19 7.8 4.3 | -23.0 -9.4 255 11 6 7.6 4.2
19000 -22.6 -8.7 265 34 17 7.8 4.3 | -21.9 -7.4 255 10 5 7.7 4.2
18500 -21.4 -6.5 265 31 16 8.0 4.4 | -20.8 -5.4 255 9 4 8.1 4.4
18000 -20.1 -4.2 265 28 14 8.6 4.7 | -19.5 -3.1 260 8 4 8.5 4.7
17500 -18.9 -2.0 265 24 13 8.6 4.7 | -18.2 -0.8 260 8 4 8.5 4.7
17000 -17.6 0.3 270 22 11 8.7 4.8 | -16.9 1.6 260 8 4 8.9 4.9
16500 -15.7 3.7 270 19 10 8.8 4.8 | -15.6 3.9 260 8 4 8.8 4.9
16000 -14.3 6.3 275 18 9 9.8 5.4 | -14.3 6.3 260 8 4 9.4 5.2
15500 -12.9 8.8 275 17 9 9.6 5.3 | -12.8 9.0 260 8 4 9.6 5.3
15000 -11.3 11.7 275 17 9 11.1 6.1 | -10.6 12.9 260 8 4 10.6 5.8
14500 -9.6 14.7 275 17 9 9.3 5.1 | -9.0 15.8 260 8 4 9.0 4.9
14000 -8.6 16.5 275 17 9 8.9 4.9 | -7.8 18.0 260 8 4 9.1 5.0
13500 -7.0 19.4 275 17 9 10.4 5.7 | -6.4 20.5 260 9 4 9.5 5.2
13000 -5.6 21.9 275 16 8 9.3 5.1 | -5.0 23.0 260 9 5 9.2 5.1
12500 -4.1 24.6 275 16 8 9.8 5.4 | -3.6 25.5 255 9 5 9.4 5.2
12000 -2.6 27.3 275 16 8 10.3 5.7 | -2.2 28.0 255 9 5 8.8 4.8
11750 -1.8 28.8 275 16 8 10.2 5.6 | -1.5 29.3 255 10 5 9.3 5.1
11500 -1.1 30.0 275 16 8 9.7 5.3 | -0.8 30.6 250 10 5 9.6 5.3
11250 -0.4 31.3 275 16 8 9.8 5.4 | -0.1 31.8 250 10 5 9.5 5.2
11000 0.4 32.7 275 15 8 10.2 5.6 | 0.6 33.1 250 10 5 8.9 4.9
10750 1.2 34.2 275 15 8 10.5 5.8 | 1.3 34.3 245 10 5 9.2 5.1
10500 1.9 35.4 275 15 8 10.3 5.7 | 2.0 35.6 245 10 5 10.0 5.5
10250 2.7 36.9 275 15 8 10.4 5.7 | 2.7 36.9 245 10 5 9.8 5.4
10000 3.5 38.3 275 15 7 10.7 5.9 | 3.4 38.1 245 10 5 9.5 5.2
9750 4.3 39.7 275 14 7 11.8 6.5 | 4.1 39.4 240 10 5 9.5 5.2
9500 5.2 41.4 275 14 7 10.6 5.8 | 4.9 40.8 240 10 5 10.3 5.6
9250 6.2 43.2 275 13 7 19.2 10.5 | 5.7 42.3 240 9 5 12.9 7.1
9000 9.5 49.1 275 12 6 84.7 46.5 | 7.0 44.6 240 8 4 23.0 12.6
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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