298
UXUS97 KGJT 261307
SRGGJT
SOARING FORECAST
NATIONAL WEATHER SERVICE GRAND JUNCTION, COLORADO
607 AM MST FRIDAY, DECEMBER 26, 2025
THIS FORECAST IS FOR FRIDAY, DECEMBER 26, 2025:
IF THE TRIGGER TEMPERATURE OF 48.7 F/9.3 C IS REACHED...THEN
THERMAL SOARING INDEX....................... GOOD
MAXIMUM RATE OF LIFT........................ 587 FT/MIN (3.0 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 14881 FT MSL (9272 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 57.0 F/14.3 C
TIME OF TRIGGER TEMPERATURE.................... 1000 MST
TIME OF OVERDEVELOPMENT........................ 1300 MST
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................. 11719 FT MSL (6110 FT AGL)
THERMAL SOARING OUTLOOK FOR SATURDAY 12/27..... POOR
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 07:32:07 / 16:57:47 MST
TOTAL POSSIBLE SUNSHINE........... 9 HR 25 MIN 40 SEC (565 MIN 40 SEC)
ALTITUDE OF SUN AT 12:14:57 MST... 27.45 DEGREES
UPPER AIR DATA FROM RAWINSONDE OBSERVATION TAKEN ON 12/26/2025 AT 0500 MST
FREEZING LEVEL.................. 8478 FT MSL (2869 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 10610 FT MSL (5001 FT AGL)
LIFTED CONDENSATION LEVEL....... 12276 FT MSL (6667 FT AGL)
LIFTED INDEX.................... +3.9
K INDEX......................... +11.8
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 -59.3 -74.7 240 68 35 1.2 0.6 M M M M M
45000 -57.4 -71.3 240 87 45 1.4 0.8 M M M M M
40000 -59.7 -75.5 240 119 61 -1.6 -0.9 M M M M M
38000 -59.0 -74.2 240 128 66 5.7 3.2 M M M M M
36000 -55.6 -68.1 240 133 68 5.7 3.1 M M M M M
34000 -51.6 -60.9 240 136 70 7.9 4.3 M M M M M
32000 -47.0 -52.6 235 128 66 7.7 4.2 M M M M M
30000 -42.4 -44.3 235 119 62 7.4 4.0 33.5 92.3 14.7 M M
29000 -40.2 -40.4 235 115 59 7.5 4.1 32.5 90.4 14.2 M M
28000 -37.9 -36.2 235 111 57 7.5 4.1 31.6 88.8 13.6 M M
27000 -35.7 -32.3 235 107 55 7.5 4.1 30.8 87.5 13.2 M M
26000 -33.5 -28.3 235 103 53 7.3 4.0 29.9 85.7 12.6 M M
25000 -31.3 -24.3 235 100 52 7.3 4.0 28.9 84.0 12.0 M M
24000 -29.1 -20.4 235 97 50 7.4 4.0 28.1 82.6 11.5 M M
23000 -27.0 -16.6 235 93 48 6.6 3.6 27.0 80.7 10.8 M M
22000 -25.0 -13.0 235 89 46 6.6 3.6 25.8 78.5 9.9 M M
21000 -23.1 -9.6 235 84 43 7.0 3.8 24.8 76.6 9.1 M M
20000 -21.9 -7.4 230 77 39 3.0 1.7 22.7 72.9 7.4 M M
19500 -21.2 -6.2 230 71 36 3.1 1.7 20.9 69.7 5.9 M M
19000 -20.8 -5.4 230 66 34 3.2 1.8 19.8 67.6 5.0 M M
18500 -20.3 -4.5 230 62 32 3.9 2.1 18.7 65.7 4.0 M M
18000 -19.5 -3.1 230 59 30 6.6 3.6 18.0 64.4 3.4 M M
17500 -18.6 -1.5 230 56 29 6.5 3.6 17.4 63.4 2.9 M M
17000 -17.7 0.1 230 54 28 5.5 3.0 16.8 62.3 2.4 M M
16500 -16.9 1.6 235 51 26 5.5 3.0 16.1 61.0 1.7 M M
16000 -16.1 3.0 235 48 25 5.9 3.3 15.4 59.7 1.1 M M
15500 -15.1 4.8 235 45 23 6.3 3.4 14.8 58.6 0.6 M M
15000 -14.2 6.4 230 42 22 6.3 3.5 14.2 57.6 0.1 M M
14500 -13.2 8.2 230 40 20 6.4 3.5 13.7 56.6 -0.4 750 3.8
14000 -12.2 10.0 230 37 19 6.4 3.5 13.1 55.6 -0.9 707 3.6
13500 -11.3 11.7 230 35 18 6.6 3.6 12.6 54.7 -1.4 663 3.4
13000 -10.3 13.5 230 33 17 6.6 3.6 12.1 53.8 -1.9 618 3.1
12500 -9.3 15.3 230 30 16 7.3 4.0 11.6 52.9 -2.4 573 2.9
12000 -8.2 17.2 230 28 14 7.2 3.9 11.2 52.2 -2.8 526 2.7
11500 -7.1 19.2 230 26 13 7.8 4.3 10.9 51.6 -3.2 479 2.4
11000 -6.0 21.2 230 24 13 7.8 4.3 10.5 51.0 -3.5 431 2.2
10500 -5.0 23.0 230 24 12 7.0 3.8 10.2 50.3 -4.0 385 2.0
10250 -4.4 24.1 230 24 12 8.5 4.7 10.0 50.0 -4.2 361 1.8
10000 -3.7 25.3 225 23 12 9.4 5.2 10.0 49.9 -4.2 333 1.7
9750 -3.1 26.4 225 23 12 8.4 4.6 9.9 49.8 -4.3 306 1.6
9500 -2.5 27.5 225 23 12 8.0 4.4 9.8 49.6 -4.5 282 1.4
9250 -1.9 28.6 220 23 12 8.2 4.5 9.6 49.3 -4.6 257 1.3
9000 -1.3 29.7 220 23 12 8.1 4.5 9.5 49.1 -4.8 232 1.2
8750 -0.8 30.6 220 22 12 7.9 4.4 9.4 48.9 -5.0 207 1.1
8500 -0.2 31.6 220 22 11 7.8 4.3 9.2 48.6 -5.1 183 0.9
8250 0.4 32.7 215 21 11 8.0 4.4 9.1 48.4 -5.3 158 0.8
8000 1.0 33.8 215 20 10 8.0 4.4 9.0 48.1 -5.5 134 0.7
7750 1.5 34.7 215 19 10 7.7 4.2 8.8 47.8 -5.7 110 0.6
7500 2.1 35.8 210 18 9 7.8 4.3 8.6 47.6 -5.9 85 0.4
7250 2.6 36.7 210 17 9 7.7 4.2 8.5 47.3 -6.0 61 0.3
7000 3.2 37.8 210 16 8 7.1 3.9 8.3 47.0 -6.2 37 0.2
6750 3.7 38.7 205 14 7 6.6 3.6 8.1 46.6 -6.5 15 0.1
6500 4.2 39.6 205 12 6 7.5 4.1 7.9 46.2 -6.7 M M
6250 4.7 40.5 200 11 6 4.5 2.4 7.7 45.8 -7.0 M M
6000 4.7 40.5 185 10 5 -5.3 -2.9 6.9 44.5 -7.7 M M
5750 3.9 39.0 180 7 4 -12.2 -6.7 5.5 41.9 -9.2 M M
5500 M M M M M M M M M M M M
5250 M M M M M M M M M M M M
5000 M M M M M M M M M M M M
* * * * * * NUMERICAL WEATHER PREDICTION MODEL FORECAST DATA VALID * * * * * *
12/26/2025 AT 0800 MST | 12/26/2025 AT 1100 MST
|
CAPE... 0.0 LI... +4.5 | CAPE... +9.3 LI... +3.7
CINH... -0.1 K INDEX... -7.3 | CINH... -5.9 K INDEX... -4.9
|
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 -82.3 245 76 39 -0.1 -0.1 | -64.1 -83.4 240 77 39 0.2 0.1
45000 -63.6 -82.5 240 94 49 0.5 0.3 | -63.8 -82.8 240 98 51 0.7 0.4
40000 -61.4 -78.5 245 102 53 1.5 0.8 | -61.6 -78.9 240 102 53 1.4 0.8
38000 -58.0 -72.4 245 104 53 7.6 4.2 | -58.2 -72.8 240 103 53 7.8 4.3
36000 -53.5 -64.3 245 104 54 7.6 4.2 | -53.5 -64.3 240 104 54 7.8 4.3
34000 -48.8 -55.8 245 104 53 8.1 4.4 | -48.8 -55.8 240 104 53 8.2 4.5
32000 -43.9 -47.0 245 101 52 8.1 4.4 | -43.8 -46.8 240 101 52 8.3 4.5
30000 -39.3 -38.7 245 98 51 6.9 3.8 | -39.1 -38.4 240 98 51 6.7 3.7
29000 -37.2 -35.0 245 96 49 6.8 3.7 | -37.2 -35.0 240 96 50 6.6 3.6
28000 -35.2 -31.4 245 94 48 6.8 3.7 | -35.2 -31.4 235 94 49 6.6 3.6
27000 -32.6 -26.7 245 91 47 7.2 3.9 | -33.2 -27.8 235 93 48 6.9 3.8
26000 -30.5 -22.9 245 88 45 7.2 3.9 | -30.5 -22.9 235 89 46 7.2 3.9
25000 -28.3 -18.9 245 85 44 7.2 3.9 | -28.3 -18.9 235 87 45 7.2 3.9
24000 -26.1 -15.0 240 82 42 6.7 3.7 | -26.2 -15.2 235 84 43 6.5 3.6
23000 -24.1 -11.4 240 79 41 6.6 3.6 | -24.3 -11.7 235 81 41 6.3 3.5
22000 -22.1 -7.8 240 77 40 6.6 3.6 | -22.4 -8.3 235 77 40 6.3 3.5
21000 -20.2 -4.4 240 74 38 6.0 3.3 | -20.5 -4.9 235 73 38 5.8 3.2
20000 -18.4 -1.1 240 70 36 6.0 3.3 | -18.7 -1.7 235 69 35 5.9 3.2
19500 -17.5 0.5 240 68 35 6.0 3.3 | -17.8 -0.0 235 66 34 5.9 3.2
19000 -16.6 2.1 240 66 34 6.1 3.3 | -17.0 1.4 235 64 33 5.9 3.2
18500 -15.7 3.7 240 64 33 5.8 3.2 | -16.1 3.0 235 62 32 6.0 3.3
18000 -14.8 5.4 240 62 32 5.8 3.2 | -15.2 4.6 235 60 31 6.0 3.3
17500 -14.0 6.8 240 60 31 5.7 3.1 | -14.3 6.3 235 58 30 6.0 3.3
17000 -13.1 8.4 240 57 30 5.6 3.1 | -13.4 7.9 235 56 29 6.0 3.3
16500 -12.3 9.9 240 55 29 5.7 3.1 | -12.5 9.5 235 54 28 6.1 3.3
16000 -11.5 11.3 240 53 27 4.6 2.5 | -11.6 11.1 235 52 27 5.6 3.0
15500 -10.8 12.6 240 51 26 4.8 2.6 | -10.8 12.6 235 50 26 5.6 3.1
15000 -10.1 13.8 240 49 25 4.4 2.4 | -10.0 14.0 235 49 25 5.3 2.9
14500 -9.5 14.9 240 46 24 4.3 2.4 | -9.2 15.4 235 47 24 5.2 2.9
14000 -8.9 16.0 235 44 22 4.4 2.4 | -8.5 16.7 235 45 23 4.8 2.6
13500 -8.3 17.1 235 41 21 4.5 2.5 | -7.8 18.0 230 42 22 4.5 2.5
13000 -7.7 18.1 235 39 20 5.0 2.7 | -7.2 19.0 230 40 21 4.6 2.5
12500 -6.9 19.6 230 37 19 5.6 3.1 | -6.6 20.1 230 38 19 4.8 2.6
12000 -6.1 21.0 230 35 18 6.0 3.3 | -6.0 21.2 225 35 18 5.2 2.9
11500 -5.2 22.6 225 33 17 6.6 3.6 | -5.2 22.6 225 34 17 5.9 3.2
11000 -4.3 24.3 225 31 16 6.8 3.7 | -4.3 24.3 220 32 16 6.3 3.5
10500 -3.3 26.1 220 30 15 7.1 3.9 | -3.4 25.9 220 30 15 6.8 3.7
10250 -2.8 27.0 220 29 15 6.2 3.4 | -2.8 27.0 220 29 15 7.7 4.2
10000 -2.4 27.7 220 28 14 6.6 3.6 | -2.3 27.9 215 29 15 8.1 4.5
9750 -1.8 28.8 220 27 14 7.9 4.3 | -1.7 28.9 215 29 15 7.6 4.2
9500 -1.3 29.7 215 26 14 7.5 4.1 | -1.2 29.8 215 28 14 7.7 4.2
9250 -0.7 30.7 215 26 13 8.1 4.5 | -0.6 30.9 210 27 14 7.9 4.3
9000 0.6 33.1 215 24 12 8.5 4.7 | 0.0 32.0 210 26 13 8.5 4.7
8750 1.2 34.2 210 23 12 7.6 4.2 | 1.2 34.2 210 24 12 8.0 4.4
8500 1.7 35.1 210 23 12 7.7 4.2 | 1.8 35.2 205 24 12 8.1 4.4
8250 2.3 36.1 205 22 11 7.4 4.1 | 2.4 36.3 205 22 12 8.1 4.5
8000 2.9 37.2 205 21 11 8.3 4.5 | 3.0 37.4 205 21 11 8.8 4.8
7750 3.5 38.3 205 20 10 9.0 4.9 | 3.7 38.7 205 20 10 9.3 5.1
7500 4.1 39.4 200 18 9 7.6 4.2 | 4.3 39.7 205 19 10 8.1 4.4
7250 4.6 40.3 195 18 9 6.5 3.5 | 4.9 40.8 200 18 9 6.8 3.7
7000 5.1 41.2 190 17 9 7.3 4.0 | 5.4 41.7 200 17 9 8.8 4.9
6750 5.7 42.3 190 15 8 6.6 3.6 | 6.2 43.2 195 16 8 10.3 5.6
6500 6.1 43.0 180 14 7 4.7 2.6 | 6.9 44.4 195 15 7 9.6 5.3
6250 6.4 43.5 170 14 7 5.9 3.2 | 7.6 45.7 190 14 7 10.0 5.5
6000 6.8 44.2 165 14 7 1.1 0.6 | 8.4 47.1 190 12 6 8.9 4.9
5750 6.3 43.3 160 9 4 -15.7 -8.6 | 9.0 48.2 190 11 6 9.4 5.1
5500 4.8 40.6 150 6 3 -19.1 -10.5 | 10.2 50.4 185 9 5 29.6 16.3
5250 M M M M M M M | M M M M M M M
5000 M M M M M M M | M M M M M M M
12/26/2025 AT 1400 MST | 12/26/2025 AT 1700 MST
|
CAPE... +17.8 LI... +2.4 | CAPE... +8.9 LI... +2.1
CINH... -1.8 K INDEX... -0.9 | CINH... -11.2 K INDEX... +3.6
|
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 -62.8 -81.0 240 77 39 0.0 0.0 | -61.6 -78.9 240 76 39 -0.4 -0.2
45000 -62.8 -81.0 240 102 52 0.2 0.1 | -62.3 -80.1 240 99 51 -0.3 -0.2
40000 -61.9 -79.4 240 110 57 0.6 0.3 | -61.9 -79.4 235 111 57 0.2 0.1
38000 -58.5 -73.3 240 111 57 8.2 4.5 | -58.8 -73.8 235 112 58 8.2 4.5
36000 -53.6 -64.5 235 110 57 8.2 4.5 | -53.9 -65.0 235 111 57 8.2 4.5
34000 -48.6 -55.5 235 108 56 8.3 4.6 | -49.0 -56.2 240 109 56 8.2 4.5
32000 -43.6 -46.5 240 104 54 8.3 4.6 | -44.1 -47.4 240 104 54 8.2 4.5
30000 -39.0 -38.2 240 100 51 6.6 3.6 | -39.3 -38.7 240 99 51 7.1 3.9
29000 -37.0 -34.6 235 97 50 6.5 3.6 | -37.1 -34.8 240 96 49 7.2 3.9
28000 -35.0 -31.0 235 95 49 6.5 3.6 | -35.0 -31.0 240 92 47 7.2 3.9
27000 -33.1 -27.6 235 93 48 6.3 3.5 | -32.9 -27.2 240 89 46 6.6 3.6
26000 -31.2 -24.2 235 89 46 6.1 3.3 | -31.2 -24.2 240 84 43 5.3 2.9
25000 -29.4 -20.9 235 84 43 6.1 3.4 | -29.7 -21.5 240 80 41 5.3 2.9
24000 -27.1 -16.8 235 79 41 6.0 3.3 | -27.7 -17.9 240 75 38 5.7 3.1
23000 -25.3 -13.5 235 75 39 5.9 3.3 | -25.9 -14.6 240 72 37 6.0 3.3
22000 -23.5 -10.3 235 72 37 5.9 3.3 | -24.1 -11.4 240 69 36 6.0 3.3
21000 -21.7 -7.1 235 68 35 6.7 3.7 | -22.3 -8.1 240 67 34 6.5 3.6
20000 -19.7 -3.5 235 65 34 6.7 3.7 | -20.3 -4.5 240 64 33 6.6 3.6
19500 -18.7 -1.7 235 64 33 6.7 3.7 | -19.3 -2.7 240 62 32 6.6 3.6
19000 -17.7 0.1 235 62 32 6.7 3.7 | -18.3 -0.9 240 61 31 6.6 3.6
18500 -16.7 1.9 235 61 31 6.4 3.5 | -17.3 0.9 240 59 30 6.5 3.6
18000 -15.8 3.6 235 59 31 6.3 3.5 | -16.3 2.7 240 58 30 6.4 3.5
17500 -14.8 5.4 235 58 30 6.3 3.4 | -15.3 4.5 240 56 29 6.4 3.5
17000 -13.9 7.0 235 56 29 6.2 3.4 | -14.4 6.1 240 55 28 5.9 3.2
16500 -13.0 8.6 235 54 28 6.2 3.4 | -13.5 7.7 240 53 27 5.9 3.3
16000 -12.1 10.2 235 52 27 6.0 3.3 | -12.7 9.1 240 52 27 5.7 3.1
15500 -11.2 11.8 235 50 26 6.1 3.3 | -11.8 10.8 235 50 26 5.7 3.1
15000 -10.3 13.5 235 48 25 5.7 3.1 | -11.0 12.2 235 48 25 5.8 3.2
14500 -9.5 14.9 235 46 24 5.6 3.1 | -10.1 13.8 235 46 24 5.9 3.3
14000 -8.7 16.3 230 44 23 5.3 2.9 | -9.2 15.4 235 44 23 5.9 3.2
13500 -7.9 17.8 230 41 21 5.0 2.7 | -8.4 16.9 230 42 21 5.8 3.2
13000 -7.3 18.9 230 39 20 5.1 2.8 | -7.6 18.3 230 39 20 5.8 3.2
12500 -6.6 20.1 225 36 19 5.2 2.9 | -6.8 19.8 230 37 19 5.6 3.1
12000 -5.9 21.4 225 34 17 5.7 3.1 | -6.0 21.2 225 34 18 5.9 3.3
11500 -4.9 23.2 220 32 16 7.2 4.0 | -5.1 22.8 225 33 17 7.5 4.1
11000 -3.9 25.0 220 31 16 7.3 4.0 | -4.0 24.8 225 31 16 7.4 4.1
10500 -2.8 27.0 215 29 15 7.6 4.2 | -3.0 26.6 225 30 15 7.2 3.9
10250 -2.3 27.9 215 28 14 7.7 4.2 | -2.4 27.7 220 29 15 7.7 4.2
10000 -1.7 28.9 215 28 14 8.3 4.5 | -1.8 28.8 220 29 15 9.9 5.4
9750 -1.1 30.0 210 28 14 8.3 4.6 | -1.1 30.0 215 29 15 9.4 5.2
9500 -0.5 31.1 210 27 14 8.2 4.5 | -0.5 31.1 215 29 15 8.0 4.4
9250 0.1 32.2 210 27 14 7.8 4.3 | 0.1 32.2 215 28 15 8.4 4.6
9000 0.7 33.3 210 26 13 10.3 5.7 | 0.7 33.3 215 28 14 8.1 4.4
8750 1.6 34.9 210 24 13 10.2 5.6 | 1.3 34.3 215 27 14 8.5 4.6
8500 2.8 37.0 210 24 12 8.5 4.6 | 2.6 36.7 210 25 13 8.8 4.8
8250 3.4 38.1 210 23 12 9.0 4.9 | 3.3 37.9 210 25 13 8.9 4.9
8000 4.1 39.4 210 22 11 9.5 5.2 | 3.9 39.0 210 24 12 8.7 4.8
7750 4.8 40.6 210 21 11 9.5 5.2 | 4.6 40.3 210 23 12 8.7 4.7
7500 5.5 41.9 210 21 11 9.3 5.1 | 5.2 41.4 205 21 11 8.6 4.7
7250 6.2 43.2 210 20 10 8.9 4.9 | 5.8 42.4 205 20 10 8.5 4.7
7000 6.9 44.4 210 19 10 9.5 5.2 | 6.5 43.7 205 20 10 8.7 4.8
6750 7.6 45.7 210 18 9 10.1 5.5 | 7.1 44.8 205 17 9 8.9 4.9
6500 8.3 46.9 210 17 9 10.5 5.7 | 7.8 46.0 200 15 8 9.0 4.9
6250 9.2 48.6 210 16 8 11.9 6.5 | 8.5 47.3 195 13 7 9.7 5.3
6000 10.0 50.0 210 15 8 8.0 4.4 | 9.2 48.6 190 12 6 7.7 4.2
5750 10.4 50.7 210 14 7 5.4 2.9 | 9.5 49.1 195 9 5 0.3 0.2
5500 12.0 53.6 210 11 6 51.7 28.3 | 9.2 48.6 175 6 3 -7.0 -3.9
5250 M M M M M M M | M M M M M M M
5000 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 AT WALKER FIELD IN GRAND
JUNCTION, COLORADO AT
NORTH LATITUDE: 39 DEG 07 MIN 00.001 SEC
WEST LONGITUDE: 108 DEG 31 MIN 59.998 SEC
ELEVATION: 4839 FEET (1475 METERS)
AND MAY NOT BE REPRESENTATIVE OF OTHER AREAS ALONG THE WESTERN SLOPE OF
COLORADO. 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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