501
UXUS97 KGJT 211306
SRGGJT
SOARING FORECAST
NATIONAL WEATHER SERVICE GRAND JUNCTION, COLORADO
606 AM MST SUNDAY, DECEMBER 21, 2025
THIS FORECAST IS FOR SUNDAY, DECEMBER 21, 2025:
IF THE TRIGGER TEMPERATURE OF 61.0 F/16.1 C IS REACHED...THEN
THERMAL SOARING INDEX....................... POOR
MAXIMUM RATE OF LIFT........................ 148 FT/MIN (0.8 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 7883 FT MSL (2276 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 57.0 F/14.3 C
TIME OF TRIGGER TEMPERATURE.................... NONE
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................. 6469 FT MSL (862 FT AGL)
THERMAL SOARING OUTLOOK FOR MONDAY 12/22....... FAIR
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 07:30:04 / 16:54:53 MST
TOTAL POSSIBLE SUNSHINE........... 9 HR 24 MIN 50 SEC (564 MIN 50 SEC)
ALTITUDE OF SUN AT 12:12:29 MST... 27.38 DEGREES
UPPER AIR DATA FROM RAWINSONDE OBSERVATION TAKEN ON 12/21/2025 AT 0500 MST
FREEZING LEVEL.................. 12424 FT MSL (6817 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 17001 FT MSL (11394 FT AGL)
LIFTED CONDENSATION LEVEL....... 12627 FT MSL (7020 FT AGL)
LIFTED INDEX.................... +6.5
K INDEX......................... +3.0
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 -63.1 -81.6 250 76 39 3.4 1.9 M M M M M
45000 -58.2 -72.8 255 87 45 1.5 0.8 M M M M M
40000 -55.9 -68.6 270 92 47 1.4 0.8 M M M M M
38000 -54.3 -65.7 265 86 44 2.9 1.6 M M M M M
36000 -52.6 -62.7 260 80 41 2.9 1.6 M M M M M
34000 -49.4 -56.9 255 76 39 7.9 4.3 M M M M M
32000 -44.7 -48.5 260 76 39 7.9 4.3 M M M M M
30000 -40.1 -40.2 260 74 38 7.3 4.0 34.8 94.7 15.8 M M
29000 -37.9 -36.2 260 72 37 7.3 4.0 33.8 92.9 15.2 M M
28000 -35.7 -32.3 260 71 36 7.3 4.0 32.9 91.3 14.7 M M
27000 -33.4 -28.1 260 69 36 8.2 4.5 32.2 89.9 14.3 M M
26000 -31.0 -23.8 260 68 35 8.2 4.5 31.5 88.7 14.0 M M
25000 -28.5 -19.3 265 67 34 8.2 4.5 30.9 87.7 13.7 M M
24000 -26.0 -14.8 265 65 34 8.5 4.7 30.5 86.8 13.4 M M
23000 -23.5 -10.3 265 62 32 8.5 4.7 29.9 85.9 13.1 M M
22000 -20.3 -4.5 265 58 30 8.5 4.7 29.4 84.9 12.9 M M
21000 -17.9 -0.2 265 55 28 7.7 4.2 28.8 83.8 12.5 M M
20000 -15.6 3.9 260 53 27 7.7 4.2 28.0 82.4 12.0 M M
19500 -14.5 5.9 260 52 27 7.6 4.2 27.7 81.8 11.8 M M
19000 -13.3 8.1 260 50 26 7.5 4.1 27.3 81.2 11.5 M M
18500 -12.2 10.0 260 49 25 7.3 4.0 26.9 80.4 11.2 M M
18000 -11.2 11.8 260 47 24 7.3 4.0 26.5 79.7 10.9 M M
17500 -10.1 13.8 255 46 24 7.2 4.0 26.1 78.9 10.6 M M
17000 -9.0 15.8 255 44 23 7.2 4.0 25.6 78.1 10.3 M M
16500 -7.9 17.8 255 43 22 7.2 4.0 25.2 77.4 9.9 M M
16000 -6.8 19.8 255 41 21 7.3 4.0 24.8 76.6 9.6 M M
15500 -5.8 21.6 255 39 20 7.2 4.0 24.4 75.9 9.3 M M
15000 -4.7 23.5 250 38 19 7.0 3.8 23.9 75.1 8.9 M M
14500 -3.7 25.3 250 36 19 7.1 3.9 23.5 74.2 8.5 M M
14000 -2.7 27.1 250 34 18 6.3 3.5 23.0 73.3 8.1 M M
13500 -1.7 28.9 250 33 17 6.5 3.6 22.4 72.3 7.6 M M
13000 -0.9 30.4 245 32 16 5.1 2.8 21.8 71.2 7.1 M M
12500 -0.1 31.8 245 30 16 5.1 2.8 21.0 69.8 6.4 M M
12000 0.6 33.1 240 30 15 4.3 2.4 20.2 68.4 5.6 M M
11500 1.1 34.0 240 29 15 4.3 2.3 19.3 66.8 4.8 M M
11000 1.7 35.1 235 28 14 4.5 2.5 18.5 65.3 3.9 M M
10500 2.4 36.3 235 27 14 4.9 2.7 17.6 63.8 3.1 M M
10250 2.8 37.0 235 26 13 6.7 3.7 17.3 63.2 2.8 M M
10000 3.3 37.9 230 25 13 7.1 3.9 17.1 62.8 2.6 M M
9750 3.8 38.8 230 23 12 6.6 3.6 16.9 62.4 2.3 M M
9500 4.3 39.7 230 22 11 6.9 3.8 16.6 62.0 2.1 M M
9250 4.7 40.5 225 20 10 6.1 3.4 16.4 61.5 1.9 M M
9000 5.2 41.4 225 19 10 5.8 3.2 16.1 61.0 1.5 M M
8750 5.6 42.1 220 18 9 6.3 3.4 15.8 60.5 1.3 M M
8500 6.1 43.0 215 17 9 6.2 3.4 15.5 60.0 1.0 M M
8250 6.5 43.7 210 16 8 5.5 3.0 15.3 59.5 0.7 M M
8000 6.8 44.2 205 15 8 4.5 2.5 14.9 58.8 0.3 M M
7750 7.2 45.0 200 15 8 4.3 2.4 14.5 58.0 -0.1 144 0.7
7500 7.5 45.5 195 14 7 4.4 2.4 14.0 57.3 -0.5 128 0.6
7250 7.8 46.0 185 15 7 4.8 2.6 13.7 56.6 -0.9 110 0.6
7000 8.2 46.8 180 15 8 3.8 2.1 13.3 55.9 -1.3 93 0.5
6750 8.4 47.1 180 15 7 3.7 2.0 12.8 55.0 -1.8 78 0.4
6500 8.5 47.3 175 14 7 -1.7 -0.9 12.2 54.0 -2.4 66 0.3
6250 8.1 46.6 165 13 7 -9.7 -5.3 11.0 51.7 -3.6 73 0.4
6000 7.6 45.7 160 12 6 1.4 0.8 9.7 49.5 -4.8 81 0.4
5750 7.9 46.2 155 10 5 0.7 0.4 9.4 48.9 -5.2 62 0.3
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 * * * * * *
12/21/2025 AT 0800 MST | 12/21/2025 AT 1100 MST
|
CAPE... 0.0 LI... +4.1 | CAPE... 0.0 LI... +4.1
CINH... -0.0 K INDEX... +15.4 | CINH... -0.1 K INDEX... +16.8
|
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 -63.1 -81.6 280 66 34 2.4 1.3 | -62.9 -81.2 275 69 35 2.2 1.2
45000 -59.8 -75.6 280 69 36 -1.6 -0.9 | -59.9 -75.8 270 76 39 -0.3 -0.2
40000 -62.1 -79.8 270 69 36 -1.3 -0.7 | -60.3 -76.5 270 66 34 -0.1 -0.1
38000 -58.8 -73.8 270 69 35 8.1 4.4 | -57.1 -70.8 270 64 33 6.5 3.5
36000 -54.0 -65.2 270 69 35 8.1 4.4 | -53.2 -63.8 270 62 32 6.5 3.5
34000 -48.4 -55.1 270 67 35 8.6 4.7 | -48.8 -55.8 270 60 31 8.2 4.5
32000 -43.3 -45.9 270 66 34 8.6 4.7 | -43.9 -47.0 270 58 30 8.2 4.5
30000 -38.4 -37.1 270 64 33 7.8 4.3 | -39.0 -38.2 270 56 29 8.3 4.6
29000 -36.1 -33.0 270 62 32 7.8 4.3 | -36.5 -33.7 270 55 28 8.3 4.6
28000 -33.8 -28.8 270 61 31 7.8 4.3 | -34.0 -29.2 270 54 28 8.3 4.6
27000 -31.5 -24.7 270 60 31 7.3 4.0 | -31.6 -24.9 270 53 27 7.7 4.2
26000 -29.3 -20.7 270 58 30 7.3 4.0 | -29.3 -20.7 270 53 27 7.7 4.2
25000 -27.1 -16.8 270 57 29 7.3 4.0 | -27.0 -16.6 270 52 27 7.7 4.2
24000 -25.0 -13.0 270 55 28 7.2 3.9 | -24.8 -12.6 270 52 27 7.2 4.0
23000 -22.8 -9.0 270 54 28 7.2 4.0 | -22.1 -7.8 270 52 27 7.3 4.0
22000 -20.7 -5.3 270 53 27 7.2 4.0 | -19.9 -3.8 270 52 27 7.3 4.0
21000 -18.1 -0.6 270 51 26 6.6 3.6 | -17.8 -0.0 270 52 27 6.9 3.8
20000 -16.2 2.8 270 49 25 6.6 3.6 | -15.8 3.6 270 50 26 6.9 3.8
19500 -15.2 4.6 270 48 25 6.6 3.6 | -14.8 5.4 265 49 25 6.9 3.8
19000 -14.3 6.3 270 48 24 6.6 3.6 | -13.7 7.3 265 49 25 6.8 3.7
18500 -13.3 8.1 270 46 24 6.5 3.6 | -12.8 9.0 265 48 25 6.5 3.6
18000 -12.3 9.9 270 45 23 6.6 3.6 | -11.8 10.8 265 47 24 6.5 3.6
17500 -11.4 11.5 270 44 23 6.2 3.4 | -10.9 12.4 260 46 24 6.3 3.4
17000 -10.5 13.1 265 43 22 6.2 3.4 | -10.0 14.0 260 45 23 6.3 3.4
16500 -9.6 14.7 265 42 21 6.1 3.4 | -9.1 15.6 260 44 22 6.1 3.4
16000 -8.7 16.3 265 40 21 6.1 3.3 | -8.2 17.2 255 42 22 6.0 3.3
15500 -7.8 18.0 265 39 20 6.1 3.3 | -7.3 18.9 255 41 21 6.0 3.3
15000 -6.9 19.6 265 37 19 5.9 3.2 | -6.4 20.5 250 39 20 6.7 3.7
14500 -6.1 21.0 260 36 19 5.9 3.2 | -5.4 22.3 250 38 19 6.7 3.7
14000 -5.2 22.6 260 35 18 6.2 3.4 | -4.5 23.9 245 36 19 6.3 3.5
13500 -4.3 24.3 260 33 17 6.2 3.4 | -3.5 25.7 245 34 18 6.4 3.5
13000 -3.4 25.9 255 31 16 6.1 3.4 | -2.6 27.3 245 33 17 5.8 3.2
12500 -2.5 27.5 250 30 15 6.1 3.4 | -1.8 28.8 240 31 16 5.7 3.1
12000 -1.6 29.1 250 28 14 6.0 3.3 | -0.9 30.4 240 30 15 5.6 3.1
11500 -0.7 30.7 245 27 14 6.0 3.3 | -0.1 31.8 235 29 15 5.6 3.1
11000 0.2 32.4 240 26 13 5.4 2.9 | 0.8 33.4 235 28 14 5.2 2.8
10500 0.9 33.6 240 24 12 5.6 3.1 | 1.5 34.7 230 26 14 5.7 3.1
10250 1.3 34.3 235 24 12 3.2 1.8 | 1.9 35.4 230 26 13 2.2 1.2
10000 1.5 34.7 235 23 12 3.6 2.0 | 1.9 35.4 230 25 13 2.6 1.4
9750 1.9 35.4 235 22 11 6.3 3.4 | 2.3 36.1 230 24 12 6.4 3.5
9500 2.3 36.1 230 20 10 5.6 3.0 | 2.7 36.9 225 23 12 5.4 3.0
9250 2.8 37.0 230 19 10 5.8 3.2 | 3.2 37.8 225 22 11 5.5 3.0
9000 3.2 37.8 225 17 9 5.4 3.0 | 3.6 38.5 225 20 10 5.1 2.8
8750 3.6 38.5 225 16 8 5.0 2.8 | 4.0 39.2 220 19 10 5.0 2.7
8500 4.0 39.2 215 15 8 4.9 2.7 | 4.3 39.7 215 18 9 5.0 2.8
8250 4.7 40.5 205 13 7 5.3 2.9 | 4.7 40.5 215 17 9 4.9 2.7
8000 5.1 41.2 200 12 6 4.8 2.6 | 5.5 41.9 210 15 8 5.3 2.9
7750 5.5 41.9 195 12 6 4.8 2.6 | 5.9 42.6 200 14 7 5.3 2.9
7500 5.8 42.4 190 11 6 5.3 2.9 | 6.2 43.2 195 13 7 4.5 2.5
7250 6.3 43.3 180 11 6 6.0 3.3 | 6.5 43.7 190 12 6 4.0 2.2
7000 6.7 44.1 175 12 6 4.1 2.2 | 6.9 44.4 185 11 6 5.5 3.0
6750 6.9 44.4 170 10 5 1.6 0.9 | 7.4 45.3 180 10 5 6.7 3.6
6500 6.9 44.4 165 10 5 0.7 0.4 | 7.8 46.0 175 9 5 6.3 3.5
6250 7.0 44.6 160 9 5 2.6 1.4 | 8.3 46.9 170 8 4 5.9 3.3
6000 7.1 44.8 155 9 5 -4.4 -2.4 | 8.8 47.8 160 8 4 7.7 4.2
5750 5.9 42.6 145 5 3 -28.8 -15.8 | 9.5 49.1 165 6 3 12.1 6.6
5500 3.3 37.9 110 4 2 -33.9 -18.6 | 10.2 50.4 155 4 2 2.9 1.6
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
12/21/2025 AT 1400 MST | 12/21/2025 AT 1700 MST
|
CAPE... 0.0 LI... +3.3 | CAPE... 0.0 LI... +3.1
CINH... -0.0 K INDEX... +15.5 | CINH... -0.2 K INDEX... +16.9
|
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 -63.4 -82.1 275 71 37 2.1 1.2 | -63.3 -81.9 270 73 37 2.5 1.4
45000 -60.3 -76.5 270 81 42 1.4 0.7 | -59.6 -75.3 265 83 43 1.8 1.0
40000 -58.3 -72.9 265 68 35 1.5 0.8 | -56.8 -70.2 270 69 35 1.6 0.9
38000 -55.6 -68.1 265 63 32 4.8 2.6 | -54.7 -66.5 265 64 33 3.9 2.1
36000 -52.7 -62.9 265 59 30 4.8 2.7 | -52.3 -62.1 260 59 30 3.9 2.1
34000 -48.9 -56.0 260 56 29 8.1 4.4 | -48.9 -56.0 260 55 29 7.9 4.3
32000 -44.1 -47.4 265 56 29 8.1 4.4 | -44.2 -47.6 265 53 27 7.8 4.3
30000 -39.2 -38.6 265 55 28 8.3 4.5 | -39.4 -38.9 265 52 27 8.3 4.6
29000 -36.7 -34.1 265 55 28 8.3 4.5 | -36.9 -34.4 265 52 27 8.3 4.6
28000 -34.2 -29.6 265 55 28 8.3 4.5 | -34.4 -29.9 265 53 27 8.3 4.6
27000 -31.8 -25.2 265 55 28 7.9 4.3 | -32.0 -25.6 265 53 27 7.8 4.3
26000 -29.4 -20.9 265 54 28 7.9 4.4 | -29.6 -21.3 265 52 27 7.9 4.3
25000 -27.1 -16.8 265 54 28 8.0 4.4 | -26.7 -16.1 265 52 27 7.9 4.3
24000 -24.2 -11.6 265 54 28 7.1 3.9 | -24.4 -11.9 265 52 27 7.3 4.0
23000 -22.1 -7.8 265 54 28 7.1 3.9 | -22.3 -8.1 265 51 27 7.3 4.0
22000 -20.0 -4.0 265 54 28 7.1 3.9 | -20.1 -4.2 265 51 26 7.3 4.0
21000 -17.9 -0.2 265 53 27 7.1 3.9 | -18.0 -0.4 265 51 26 7.2 4.0
20000 -15.8 3.6 265 52 27 7.1 3.9 | -15.9 3.4 260 50 26 7.2 4.0
19500 -14.7 5.5 265 52 27 7.1 3.9 | -14.8 5.4 260 50 26 7.2 4.0
19000 -13.7 7.3 265 51 26 7.1 3.9 | -13.7 7.3 260 49 25 7.2 3.9
18500 -12.6 9.3 265 50 26 7.2 3.9 | -12.7 9.1 260 48 25 7.1 3.9
18000 -11.6 11.1 265 49 25 7.2 3.9 | -11.6 11.1 260 48 24 7.1 3.9
17500 -10.5 13.1 260 48 25 7.0 3.8 | -10.6 12.9 260 47 24 7.1 3.9
17000 -9.5 14.9 260 47 24 7.0 3.8 | -9.5 14.9 260 46 23 7.1 3.9
16500 -8.5 16.7 260 46 23 6.9 3.8 | -8.5 16.7 260 45 23 7.0 3.8
16000 -7.5 18.5 260 44 23 6.8 3.7 | -7.5 18.5 260 43 22 6.9 3.8
15500 -6.5 20.3 260 43 22 6.8 3.7 | -6.5 20.3 260 42 22 6.9 3.8
15000 -5.5 22.1 260 41 21 6.6 3.6 | -5.5 22.1 260 41 21 6.5 3.5
14500 -4.6 23.7 260 40 20 6.6 3.6 | -4.5 23.9 260 39 20 6.5 3.6
14000 -3.6 25.5 255 38 20 6.2 3.4 | -3.6 25.5 260 38 19 6.1 3.3
13500 -2.7 27.1 255 37 19 6.2 3.4 | -2.7 27.1 260 36 19 6.1 3.4
13000 -1.9 28.6 250 36 18 5.1 2.8 | -1.9 28.6 255 34 18 5.2 2.9
12500 -1.2 29.8 245 35 18 4.7 2.6 | -1.2 29.8 255 33 17 5.0 2.7
12000 -0.6 30.9 245 34 17 3.7 2.0 | -0.5 31.1 250 31 16 4.4 2.4
11500 -0.1 31.8 240 32 17 3.1 1.7 | 0.1 32.2 245 29 15 4.2 2.3
11000 0.3 32.5 235 31 16 3.7 2.0 | 0.7 33.3 240 27 14 4.8 2.7
10500 0.9 33.6 230 28 14 4.1 2.2 | 1.5 34.7 235 25 13 5.4 2.9
10250 1.2 34.2 230 27 14 3.3 1.8 | 1.9 35.4 235 24 12 4.6 2.5
10000 1.5 34.7 230 25 13 5.1 2.8 | 2.2 36.0 230 23 12 5.7 3.1
9750 2.0 35.6 225 24 12 7.3 4.0 | 2.8 37.0 230 22 11 7.3 4.0
9500 2.5 36.5 220 22 11 6.6 3.6 | 3.3 37.9 225 21 11 6.9 3.8
9250 3.0 37.4 220 21 11 7.1 3.9 | 3.8 38.8 220 21 11 6.9 3.8
9000 3.6 38.5 215 19 10 7.4 4.0 | 4.8 40.6 215 18 9 7.0 3.8
8750 4.1 39.4 210 18 9 7.1 3.9 | 5.4 41.7 210 18 10 6.9 3.8
8500 5.2 41.4 205 16 8 7.0 3.8 | 5.9 42.6 210 19 10 7.2 4.0
8250 5.7 42.3 200 15 8 7.2 4.0 | 6.4 43.5 205 17 9 7.7 4.2
8000 6.3 43.3 200 13 7 8.4 4.6 | 7.0 44.6 205 16 8 7.5 4.1
7750 7.0 44.6 200 13 7 8.9 4.9 | 7.6 45.7 200 16 8 7.5 4.1
7500 7.6 45.7 195 12 6 7.7 4.2 | 8.1 46.6 200 15 8 7.7 4.2
7250 8.1 46.6 195 11 6 6.7 3.7 | 8.7 47.7 195 14 7 7.9 4.3
7000 8.7 47.7 195 10 5 9.6 5.3 | 9.3 48.7 190 13 7 7.5 4.1
6750 9.5 49.1 195 10 5 10.8 5.9 | 9.9 49.8 190 12 6 7.2 3.9
6500 10.2 50.4 195 9 4 9.2 5.1 | 10.4 50.7 190 10 5 6.6 3.6
6250 10.9 51.6 195 7 4 9.2 5.0 | 10.9 51.6 185 9 5 7.8 4.3
6000 11.6 52.9 195 6 3 9.7 5.3 | 11.4 52.5 180 7 4 2.9 1.6
5750 12.4 54.3 195 7 3 13.1 7.2 | 11.0 51.8 180 5 2 -13.5 -7.4
5500 13.6 56.5 195 5 2 19.7 10.8 | 9.8 49.6 165 2 1 -14.2 -7.8
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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