670
UXUS97 KGJT 201306
SRGGJT
SOARING FORECAST
NATIONAL WEATHER SERVICE GRAND JUNCTION, COLORADO
706 AM MDT TUESDAY, OCTOBER 20, 2026
THIS FORECAST IS FOR TUESDAY, OCTOBER 20, 2026:
IF THE TRIGGER TEMPERATURE OF 68.7 F/20.4 C IS REACHED...THEN
THERMAL SOARING INDEX....................... FAIR
MAXIMUM RATE OF LIFT........................ 322 FT/MIN (1.6 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 9934 FT MSL (4326 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 69.0 F/21.0 C
TIME OF TRIGGER TEMPERATURE.................... 1500 MDT
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................. 7187 FT MSL (1579 FT AGL)
THERMAL SOARING OUTLOOK FOR WEDNESDAY 10/21.... POOR
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 07:29:16 / 18:28:25 MDT
TOTAL POSSIBLE SUNSHINE........... 10 HR 59 MIN 9 SEC (659 MIN 9 SEC)
ALTITUDE OF SUN AT 12:58:50 MDT... 40.33 DEGREES
UPPER AIR DATA FROM RAWINSONDE OBSERVATION TAKEN ON 10/20/2026 AT 0600 MDT
FREEZING LEVEL.................. 12958 FT MSL (7350 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 14182 FT MSL (8574 FT AGL)
LIFTED CONDENSATION LEVEL....... 13145 FT MSL (7537 FT AGL)
LIFTED INDEX.................... +2.8
K INDEX......................... +19.3
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 -63.9 -83.0 220 40 21 3.1 1.7 M M M M M
45000 -58.5 -73.3 220 47 24 5.0 2.8 M M M M M
40000 -51.0 -59.8 230 56 29 4.3 2.4 M M M M M
38000 -48.4 -55.1 230 64 33 4.3 2.4 M M M M M
36000 -45.8 -50.4 235 72 37 4.3 2.4 M M M M M
34000 -41.8 -43.2 235 76 39 6.8 3.7 M M M M M
32000 -37.7 -35.9 235 77 39 6.8 3.7 M M M M M
30000 -33.6 -28.5 230 69 35 7.1 3.9 42.0 107.6 16.2 M M
29000 -31.5 -24.7 230 63 32 7.1 3.9 40.9 105.7 15.6 M M
28000 -29.4 -20.9 225 57 30 7.1 3.9 40.0 104.1 15.1 M M
27000 -27.2 -17.0 225 52 27 7.3 4.0 39.0 102.2 14.4 M M
26000 -25.1 -13.2 225 46 24 7.3 4.0 38.0 100.4 13.8 M M
25000 -22.9 -9.2 230 41 21 7.3 4.0 37.2 98.9 13.2 M M
24000 -21.0 -5.8 230 38 20 5.6 3.1 35.9 96.6 12.3 M M
23000 -19.4 -2.9 235 38 19 5.6 3.1 34.3 93.8 11.2 M M
22000 -17.7 0.1 235 37 19 5.5 3.0 32.9 91.2 10.1 M M
21000 -15.8 3.6 240 36 18 6.6 3.6 31.6 88.9 9.1 M M
20000 -13.4 7.9 240 33 17 6.6 3.6 30.2 86.4 8.0 M M
19500 -12.4 9.7 240 32 17 6.6 3.6 29.7 85.5 7.6 M M
19000 -11.4 11.5 240 31 16 7.1 3.9 29.2 84.6 7.2 M M
18500 -10.4 13.3 235 30 16 7.0 3.9 28.8 83.8 6.8 M M
18000 -9.3 15.3 235 29 15 6.8 3.8 28.3 83.0 6.5 M M
17500 -8.3 17.1 235 28 15 6.6 3.6 27.8 82.0 6.0 M M
17000 -7.4 18.7 230 28 14 6.6 3.6 27.2 81.0 5.6 M M
16500 -6.4 20.5 230 27 14 6.2 3.4 26.7 80.0 5.1 M M
16000 -5.5 22.1 230 26 14 6.2 3.4 26.1 78.9 4.6 M M
15500 -4.6 23.7 225 26 13 6.0 3.3 25.5 77.9 4.1 M M
15000 -3.7 25.3 225 24 13 6.0 3.3 24.8 76.7 3.5 M M
14500 -2.9 26.8 225 23 12 6.2 3.4 24.2 75.6 2.9 M M
14000 -2.0 28.4 225 22 11 6.4 3.5 23.7 74.6 2.3 M M
13500 -1.1 30.0 220 21 11 6.8 3.7 23.1 73.6 1.7 M M
13000 -0.1 31.8 220 20 10 7.7 4.2 22.7 72.9 1.3 M M
12500 1.0 33.8 215 19 10 7.9 4.3 22.4 72.3 0.9 M M
12000 2.2 36.0 215 19 10 8.9 4.9 22.2 72.0 0.7 M M
11500 3.5 38.3 210 19 10 8.8 4.8 22.1 71.7 0.5 M M
11000 4.8 40.6 210 19 10 8.4 4.6 21.9 71.4 0.3 M M
10500 6.0 42.8 205 18 9 10.2 5.6 21.6 71.0 0.1 M M
10250 6.8 44.2 205 18 9 10.2 5.6 21.8 71.2 0.2 M M
10000 7.4 45.3 200 17 9 7.6 4.1 21.6 71.0 0.1 M M
9750 8.0 46.4 195 17 9 8.5 4.7 21.5 70.7 -0.1 307 1.6
9500 8.6 47.5 195 17 9 7.2 4.0 21.4 70.5 -0.2 282 1.4
9250 9.1 48.4 190 17 9 7.0 3.8 21.2 70.1 -0.4 259 1.3
9000 9.7 49.5 190 16 8 7.7 4.2 21.0 69.8 -0.6 234 1.2
8750 10.3 50.5 185 15 8 8.0 4.4 20.8 69.5 -0.7 210 1.1
8500 10.8 51.4 180 15 8 6.3 3.5 20.7 69.2 -0.9 185 0.9
8250 11.2 52.2 175 15 8 4.5 2.5 20.3 68.6 -1.2 167 0.8
8000 11.6 52.9 165 14 7 5.2 2.9 19.9 67.9 -1.6 148 0.8
7750 12.0 53.6 160 14 7 5.6 3.1 19.6 67.3 -1.9 129 0.7
7500 12.4 54.3 155 13 7 4.4 2.4 19.3 66.7 -2.3 109 0.6
7250 12.7 54.9 150 12 6 3.3 1.8 18.8 65.8 -2.7 94 0.5
7000 12.9 55.2 145 12 6 3.3 1.8 18.3 64.9 -3.2 79 0.4
6750 13.1 55.6 140 11 6 1.5 0.8 17.8 64.0 -3.7 66 0.3
6500 13.1 55.6 135 10 5 -1.0 -0.6 17.0 62.6 -4.5 58 0.3
6250 13.0 55.4 130 9 5 -2.6 -1.4 16.1 61.1 -5.4 55 0.3
6000 12.8 55.0 125 8 4 1.1 0.6 15.3 59.5 -6.2 51 0.3
5750 12.9 55.2 120 7 4 -4.4 -2.4 14.6 58.3 -6.9 43 0.2
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 * * * * * *
10/20/2026 AT 0900 MDT | 10/20/2026 AT 1200 MDT
|
CAPE... 0.0 LI... +1.4 | CAPE... +25.6 LI... +1.3
CINH... -1.7 K INDEX... +20.7 | CINH... -25.7 K INDEX... +18.8
|
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 -63.2 -81.8 240 34 17 3.4 1.9 | -63.3 -81.9 235 31 16 2.9 1.6
45000 -57.3 -71.1 245 36 19 5.6 3.1 | -57.9 -72.2 235 37 19 5.6 3.1
40000 -48.9 -56.0 250 35 18 6.1 3.4 | -49.4 -56.9 240 39 20 6.2 3.4
38000 -44.6 -48.3 255 33 17 6.3 3.5 | -45.1 -49.2 245 37 19 6.3 3.5
36000 -40.9 -41.6 255 32 16 6.3 3.4 | -41.3 -42.3 250 35 18 6.3 3.4
34000 -38.8 -37.8 255 28 15 2.1 1.1 | -39.0 -38.2 250 32 16 2.7 1.5
32000 -37.6 -35.7 250 24 12 2.0 1.1 | -37.4 -35.3 255 29 15 2.7 1.5
30000 -34.5 -30.1 250 20 10 7.2 3.9 | -34.4 -29.9 255 27 14 6.4 3.5
29000 -32.3 -26.1 250 19 10 7.2 3.9 | -32.5 -26.5 260 26 13 6.4 3.5
28000 -30.2 -22.4 255 17 9 7.2 3.9 | -30.6 -23.1 260 25 13 6.3 3.5
27000 -28.0 -18.4 255 15 8 7.2 4.0 | -28.4 -19.1 260 23 12 8.0 4.4
26000 -25.9 -14.6 265 14 7 7.2 4.0 | -26.0 -14.8 260 22 11 8.0 4.4
25000 -23.7 -10.7 270 12 6 7.2 3.9 | -23.6 -10.5 260 20 11 7.9 4.4
24000 -21.8 -7.2 275 11 6 4.9 2.7 | -21.4 -6.5 260 19 10 6.0 3.3
23000 -19.9 -3.8 280 9 5 5.1 2.8 | -19.2 -2.6 260 16 8 6.1 3.3
22000 -18.4 -1.1 285 8 4 5.1 2.8 | -17.3 0.9 260 14 7 6.1 3.4
21000 -16.6 2.1 285 7 4 6.4 3.5 | -15.6 3.9 260 12 6 5.9 3.2
20000 -14.8 5.4 285 8 4 6.4 3.5 | -13.9 7.0 260 11 5 5.9 3.3
19500 -13.8 7.2 285 8 4 6.5 3.5 | -13.0 8.6 255 10 5 6.0 3.3
19000 -12.9 8.8 285 8 4 5.9 3.2 | -12.1 10.2 255 9 5 6.3 3.5
18500 -12.1 10.2 280 8 4 5.6 3.1 | -11.2 11.8 255 9 5 6.5 3.6
18000 -11.3 11.7 275 8 4 5.6 3.1 | -10.2 13.6 255 8 4 6.5 3.5
17500 -10.5 13.1 265 8 4 5.9 3.2 | -9.4 15.1 255 8 4 5.5 3.0
17000 -9.6 14.7 260 9 4 5.9 3.2 | -8.6 16.5 250 8 4 5.7 3.1
16500 -8.8 16.2 255 9 4 5.2 2.9 | -7.8 18.0 245 8 4 4.8 2.7
16000 -8.1 17.4 245 9 5 5.1 2.8 | -7.1 19.2 240 8 4 4.7 2.6
15500 -7.4 18.7 235 9 5 5.3 2.9 | -6.4 20.5 235 8 4 4.6 2.5
15000 -6.6 20.1 235 10 5 5.6 3.0 | -5.8 21.6 235 9 4 4.5 2.5
14500 -5.8 21.6 230 10 5 5.7 3.1 | -5.2 22.6 230 9 5 4.8 2.6
14000 -4.9 23.2 230 10 5 6.8 3.7 | -4.4 24.1 225 9 5 6.1 3.3
13500 -3.9 25.0 225 11 6 6.7 3.7 | -3.6 25.5 225 9 5 6.0 3.3
13000 -2.9 26.8 225 11 6 7.7 4.2 | -2.6 27.3 220 9 5 7.6 4.2
12500 -1.8 28.8 230 11 6 7.6 4.2 | -1.5 29.3 220 10 5 7.5 4.1
12000 -0.6 30.9 230 11 6 8.1 4.5 | -0.4 31.3 220 9 5 7.9 4.3
11500 0.5 32.9 225 10 5 8.0 4.4 | 0.7 33.3 220 9 5 7.8 4.3
11000 1.8 35.2 225 10 5 8.7 4.8 | 1.9 35.4 220 9 4 8.5 4.6
10500 3.0 37.4 220 10 5 9.1 5.0 | 3.1 37.6 220 8 4 8.6 4.7
10250 3.7 38.7 220 9 5 6.9 3.8 | 3.7 38.7 215 8 4 7.4 4.0
10000 4.1 39.4 220 9 4 7.0 3.8 | 4.2 39.6 215 8 4 8.0 4.4
9750 4.7 40.5 215 9 4 9.1 5.0 | 4.9 40.8 215 7 4 9.5 5.2
9500 5.4 41.7 210 8 4 8.6 4.7 | 5.6 42.1 210 7 4 9.1 5.0
9250 6.0 42.8 210 8 4 8.2 4.5 | 6.3 43.3 210 7 3 8.6 4.7
9000 6.5 43.7 205 8 4 7.1 3.9 | 6.9 44.4 210 6 3 7.7 4.2
8750 7.0 44.6 200 8 4 6.6 3.6 | 7.4 45.3 205 6 3 7.4 4.1
8500 7.5 45.5 190 8 4 6.5 3.6 | 7.9 46.2 200 6 3 7.4 4.0
8250 8.5 47.3 180 8 4 6.5 3.5 | 9.0 48.2 190 6 3 7.2 4.0
8000 8.9 48.0 175 8 4 5.9 3.3 | 9.6 49.3 185 5 3 8.5 4.6
7750 9.3 48.7 170 7 4 5.3 2.9 | 10.2 50.4 180 5 3 7.8 4.3
7500 9.7 49.5 165 7 4 5.0 2.7 | 10.7 51.3 170 5 3 6.4 3.5
7250 10.1 50.2 160 8 4 5.0 2.8 | 11.2 52.2 165 5 3 6.6 3.6
7000 10.4 50.7 155 8 4 4.8 2.6 | 11.7 53.1 160 5 2 10.1 5.5
6750 10.7 51.3 150 6 3 3.4 1.9 | 12.6 54.7 160 4 2 10.4 5.7
6500 10.9 51.6 145 6 3 2.4 1.3 | 13.2 55.8 155 4 2 8.5 4.6
6250 11.1 52.0 140 6 3 3.3 1.8 | 13.8 56.8 155 4 2 8.1 4.4
6000 11.4 52.5 135 5 3 1.4 0.8 | 14.5 58.1 150 4 2 11.8 6.5
5750 11.2 52.2 115 4 2 -4.9 -2.7 | 15.7 60.3 150 4 2 21.4 11.8
5500 10.8 51.4 095 3 2 -3.6 -2.0 | 17.0 62.6 145 4 2 5.1 2.8
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
10/20/2026 AT 1500 MDT | 10/20/2026 AT 1800 MDT
|
CAPE... +24.1 LI... +0.9 | CAPE... +6.3 LI... +1.0
CINH... -7.6 K INDEX... +19.8 | CINH... -16.7 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 -63.3 -81.9 230 32 17 3.0 1.6 | -64.1 -83.4 225 35 18 3.1 1.7
45000 -57.9 -72.2 230 40 21 5.3 2.9 | -58.5 -73.3 230 42 22 5.5 3.0
40000 -49.9 -57.8 240 43 22 6.0 3.3 | -50.2 -58.4 235 44 23 5.9 3.2
38000 -45.8 -50.4 245 40 21 6.1 3.3 | -46.2 -51.2 240 43 22 5.9 3.2
36000 -42.2 -44.0 250 38 19 6.0 3.3 | -42.7 -44.9 245 42 21 5.8 3.2
34000 -39.7 -39.5 255 38 20 3.4 1.8 | -40.4 -40.7 250 42 22 3.0 1.7
32000 -37.7 -35.9 260 40 21 3.3 1.8 | -38.6 -37.5 255 44 23 3.1 1.7
30000 -34.3 -29.7 265 40 21 7.0 3.8 | -34.5 -30.1 255 41 21 8.8 4.8
29000 -32.2 -26.0 265 39 20 7.0 3.8 | -31.8 -25.2 255 38 20 8.8 4.8
28000 -30.1 -22.2 265 39 20 6.9 3.8 | -29.2 -20.6 255 35 18 8.9 4.9
27000 -27.8 -18.0 265 36 19 8.2 4.5 | -26.8 -16.2 250 33 17 7.9 4.4
26000 -25.3 -13.5 260 33 17 8.3 4.5 | -24.4 -11.9 250 30 15 7.9 4.4
25000 -22.8 -9.0 260 29 15 8.2 4.5 | -22.0 -7.6 245 27 14 7.9 4.3
24000 -20.0 -4.0 260 25 13 7.0 3.8 | -19.8 -3.6 245 25 13 6.5 3.5
23000 -17.9 -0.2 260 21 11 7.0 3.8 | -17.4 0.7 240 22 11 6.4 3.5
22000 -15.8 3.6 255 18 9 7.3 4.0 | -15.5 4.1 235 20 10 6.5 3.6
21000 -14.3 6.3 250 16 8 4.4 2.4 | -14.0 6.8 235 18 9 4.6 2.5
20000 -13.0 8.6 245 14 7 4.5 2.5 | -12.7 9.1 235 17 9 4.6 2.5
19500 -12.3 9.9 245 13 7 4.5 2.5 | -12.0 10.4 235 16 8 4.6 2.5
19000 -11.6 11.1 240 12 6 5.8 3.2 | -11.3 11.7 235 15 8 5.8 3.2
18500 -10.7 12.7 240 12 6 6.2 3.4 | -10.4 13.3 240 15 8 6.1 3.3
18000 -9.8 14.4 235 12 6 6.3 3.4 | -9.5 14.9 240 14 7 6.2 3.4
17500 -8.9 16.0 235 11 6 6.1 3.4 | -8.6 16.5 240 14 7 6.6 3.6
17000 -8.0 17.6 235 11 6 6.3 3.4 | -7.6 18.3 240 13 7 6.7 3.7
16500 -7.2 19.0 230 11 6 5.0 2.7 | -6.7 19.9 235 12 6 5.9 3.2
16000 -6.5 20.3 225 11 5 4.8 2.7 | -5.9 21.4 230 12 6 5.8 3.2
15500 -5.9 21.4 220 11 5 4.9 2.7 | -5.0 23.0 225 11 6 5.5 3.0
15000 -5.2 22.6 215 11 5 5.0 2.7 | -4.3 24.3 215 11 6 5.3 2.9
14500 -4.5 23.9 210 11 5 5.2 2.9 | -3.6 25.5 210 11 6 5.4 3.0
14000 -3.7 25.3 210 11 5 6.4 3.5 | -2.8 27.0 200 11 6 5.9 3.2
13500 -2.8 27.0 205 10 5 6.3 3.5 | -1.9 28.6 195 11 6 6.0 3.3
13000 -1.8 28.8 200 10 5 7.7 4.2 | -1.0 30.2 190 11 6 7.3 4.0
12500 -0.7 30.7 200 10 5 7.5 4.1 | 0.0 32.0 190 11 6 7.2 3.9
12000 0.4 32.7 200 10 5 8.1 4.5 | 1.1 34.0 185 11 6 8.2 4.5
11500 1.6 34.9 200 9 5 8.1 4.4 | 2.3 36.1 185 10 5 8.1 4.4
11000 2.8 37.0 200 8 4 8.4 4.6 | 3.5 38.3 185 9 5 8.2 4.5
10500 4.0 39.2 200 8 4 8.8 4.8 | 4.7 40.5 180 8 4 8.3 4.5
10250 4.6 40.3 200 7 4 6.7 3.7 | 5.2 41.4 180 7 4 6.8 3.7
10000 5.0 41.0 195 7 3 7.3 4.0 | 5.7 42.3 175 7 4 8.1 4.5
9750 5.7 42.3 195 6 3 9.8 5.4 | 6.4 43.5 175 6 3 10.2 5.6
9500 6.4 43.5 195 6 3 9.2 5.0 | 7.2 45.0 175 6 3 9.7 5.3
9250 7.1 44.8 195 5 3 8.9 4.9 | 7.9 46.2 175 5 3 9.4 5.1
9000 7.7 45.9 185 4 2 8.8 4.8 | 8.5 47.3 165 5 2 8.8 4.8
8750 9.0 48.2 195 4 2 8.9 4.9 | 9.2 48.6 165 4 2 8.8 4.8
8500 9.7 49.5 195 4 2 8.4 4.6 | 9.8 49.6 170 3 2 8.7 4.8
8250 10.3 50.5 185 3 2 8.8 4.8 | 11.1 52.0 155 2 1 8.3 4.5
8000 11.0 51.8 190 3 1 10.3 5.6 | 11.7 53.1 145 1 1 8.9 4.9
7750 11.8 53.2 195 3 1 9.9 5.4 | 12.4 54.3 140 1 0 8.2 4.5
7500 12.5 54.5 195 3 1 8.7 4.8 | 12.9 55.2 000 0 0 7.1 3.9
7250 13.1 55.6 195 2 1 8.9 4.9 | 13.4 56.1 355 1 0 7.3 4.0
7000 13.8 56.8 195 2 1 11.1 6.1 | 14.0 57.2 350 1 1 9.1 5.0
6750 14.7 58.5 200 2 1 11.0 6.0 | 14.8 58.6 345 1 1 9.3 5.1
6500 15.4 59.7 200 2 1 9.7 5.3 | 15.4 59.7 335 2 1 7.9 4.4
6250 16.2 61.2 205 1 1 9.2 5.1 | 16.0 60.8 330 3 1 8.8 4.8
6000 16.9 62.4 205 1 1 11.5 6.3 | 16.6 61.9 330 3 2 7.2 3.9
5750 18.0 64.4 215 1 1 19.8 10.9 | 16.9 62.4 325 2 1 2.6 1.4
5500 19.4 66.9 235 1 0 14.2 7.8 | 17.1 62.8 320 3 2 6.6 3.6
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
________________________________________________________________________________
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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