009
UXUS97 KGJT 281306
SRGGJT
SOARING FORECAST
NATIONAL WEATHER SERVICE GRAND JUNCTION, COLORADO
706 AM MDT MONDAY, SEPTEMBER 28, 2026
THIS FORECAST IS FOR MONDAY, SEPTEMBER 28, 2026:
IF THE TRIGGER TEMPERATURE OF 63.7 F/17.6 C IS REACHED...THEN
THERMAL SOARING INDEX....................... POOR
MAXIMUM RATE OF LIFT........................ 15 FT/MIN (0.1 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 11113 FT MSL (5505 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 67.0 F/19.9 C
TIME OF TRIGGER TEMPERATURE.................... 0900 MDT
TIME OF OVERDEVELOPMENT........................ NONE
MIDDLE/HIGH CLOUDS DURING SOARING WINDOW....... BROKEN/OVERCAST OPAQUE MIDDLE
SURFACE WINDS DURING SOARING WINDOW............ 20 MPH OR LESS
HEIGHT OF THE -3 THERMAL INDEX................. 8609 FT MSL (3000 FT AGL)
THERMAL SOARING OUTLOOK FOR TUESDAY 09/29...... POOR
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 07:07:44 / 19:01:40 MDT
TOTAL POSSIBLE SUNSHINE........... 11 HR 53 MIN 56 SEC (713 MIN 56 SEC)
ALTITUDE OF SUN AT 13:04:42 MDT... 48.62 DEGREES
UPPER AIR DATA FROM RAWINSONDE OBSERVATION TAKEN ON 09/28/2026 AT 0600 MDT
FREEZING LEVEL.................. 12713 FT MSL (7105 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 10232 FT MSL (4624 FT AGL)
LIFTED CONDENSATION LEVEL....... 10685 FT MSL (5077 FT AGL)
LIFTED INDEX.................... +1.4
K INDEX......................... +23.7
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 -60.6 -77.1 240 48 25 3.1 1.7 M M M M M
45000 -55.5 -67.9 235 62 32 4.4 2.4 M M M M M
40000 -48.9 -56.0 225 71 37 3.9 2.1 M M M M M
38000 -46.8 -52.2 215 71 36 3.1 1.7 M M M M M
36000 -44.9 -48.8 205 72 37 3.1 1.7 M M M M M
34000 -41.3 -42.3 205 72 37 7.4 4.1 M M M M M
32000 -36.9 -34.4 205 73 38 7.4 4.0 M M M M M
30000 -32.4 -26.3 210 69 36 7.6 4.2 43.5 110.3 18.2 M M
29000 -30.1 -22.2 210 67 34 7.6 4.2 42.6 108.8 17.8 M M
28000 -27.8 -18.0 215 64 33 7.6 4.2 41.9 107.5 17.4 M M
27000 -25.6 -14.1 220 61 31 7.2 4.0 41.0 105.9 16.9 M M
26000 -23.5 -10.3 220 56 29 7.2 4.0 40.0 104.0 16.3 M M
25000 -21.3 -6.3 220 52 27 7.3 4.0 39.1 102.4 15.7 M M
24000 -19.3 -2.7 225 48 25 5.4 3.0 38.1 100.6 15.1 M M
23000 -17.6 0.3 225 43 22 5.6 3.1 36.5 97.7 13.9 M M
22000 -15.9 3.4 230 39 20 5.6 3.1 35.0 95.1 12.9 M M
21000 -13.5 7.7 230 34 17 6.8 3.7 33.5 92.2 11.8 M M
20000 -11.5 11.3 230 29 15 6.8 3.7 32.4 90.3 11.0 M M
19500 -10.5 13.1 235 27 14 6.8 3.7 31.9 89.4 10.6 M M
19000 -9.5 14.9 235 25 13 6.6 3.6 31.5 88.6 10.3 M M
18500 -8.6 16.5 235 22 11 5.8 3.2 30.8 87.4 9.7 M M
18000 -7.7 18.1 230 19 10 5.9 3.2 30.1 86.2 9.2 M M
17500 -6.9 19.6 230 17 9 5.2 2.9 29.4 85.0 8.6 M M
17000 -6.2 20.8 230 15 8 5.2 2.8 28.6 83.5 7.8 M M
16500 -5.5 22.1 225 14 7 5.1 2.8 27.9 82.2 7.1 M M
16000 -4.9 23.2 220 13 7 4.8 2.7 27.1 80.7 6.3 M M
15500 -4.3 24.3 220 11 6 5.0 2.7 26.2 79.2 5.5 M M
15000 -3.6 25.5 215 10 5 4.9 2.7 25.4 77.8 4.7 M M
14500 -2.9 26.8 215 9 5 4.9 2.7 24.6 76.3 4.0 M M
14000 -2.2 28.0 210 9 5 5.8 3.2 23.9 75.0 3.2 M M
13500 -1.4 29.5 205 9 4 5.9 3.2 23.3 73.9 2.6 M M
13000 -0.5 31.1 205 8 4 6.2 3.4 22.7 72.8 2.0 M M
12500 0.4 32.7 200 8 4 6.4 3.5 22.1 71.8 1.5 M M
12000 1.3 34.3 195 8 4 6.5 3.6 21.6 70.8 1.0 M M
11500 2.2 36.0 195 8 4 6.6 3.6 21.1 69.9 0.4 M M
11000 3.2 37.8 190 7 4 6.3 3.4 20.6 69.0 -0.1 407 2.1
10500 4.0 39.2 185 7 4 6.2 3.4 19.9 67.9 -0.7 368 1.9
10250 4.5 40.1 185 7 3 7.2 3.9 19.7 67.5 -1.0 346 1.8
10000 5.0 41.0 180 7 3 6.5 3.5 19.5 67.1 -1.2 324 1.6
9750 5.4 41.7 180 7 3 5.6 3.1 19.2 66.5 -1.5 304 1.5
9500 5.8 42.4 180 7 3 5.9 3.2 18.9 66.0 -1.8 284 1.4
9250 6.2 43.2 180 6 3 5.9 3.2 18.6 65.4 -2.1 264 1.3
9000 6.7 44.1 170 6 3 5.9 3.3 18.3 64.9 -2.4 243 1.2
8750 7.1 44.8 170 6 3 6.0 3.3 18.0 64.4 -2.7 223 1.1
8500 7.5 45.5 170 6 3 5.7 3.1 17.7 63.8 -3.1 202 1.0
8250 8.0 46.4 170 7 3 6.7 3.7 17.4 63.3 -3.4 182 0.9
8000 8.5 47.3 165 6 3 6.6 3.6 17.2 62.9 -3.6 159 0.8
7750 8.9 48.0 165 6 3 5.7 3.1 16.9 62.4 -3.9 139 0.7
7500 9.3 48.7 160 6 3 5.7 3.1 16.6 61.9 -4.2 119 0.6
7250 9.8 49.6 160 6 3 6.7 3.7 16.3 61.3 -4.5 99 0.5
7000 10.3 50.5 155 6 3 6.7 3.7 16.1 61.0 -4.7 76 0.4
6750 10.7 51.3 155 6 3 5.5 3.0 15.8 60.4 -5.1 56 0.3
6500 11.1 52.0 155 5 3 5.8 3.2 15.5 59.9 -5.4 36 0.2
6250 11.5 52.7 150 4 2 5.8 3.2 15.2 59.4 -5.7 16 0.1
6000 11.9 53.4 145 3 2 4.3 2.3 14.9 58.8 -6.1 M M
5750 12.0 53.6 140 2 1 1.1 0.6 14.3 57.8 -6.7 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 * * * * * *
09/28/2026 AT 0900 MDT | 09/28/2026 AT 1200 MDT
|
CAPE... +21.0 LI... +0.4 | CAPE... +103.1 LI... +0.4
CINH... -29.7 K INDEX... +27.2 | CINH... -9.7 K INDEX... +26.3
|
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 -61.4 -78.5 260 42 22 2.3 1.3 | -61.4 -78.5 250 40 20 2.3 1.2
45000 -57.2 -71.0 255 62 32 4.7 2.6 | -57.2 -71.0 250 58 30 4.5 2.5
40000 -50.0 -58.0 255 74 38 2.6 1.4 | -50.2 -58.4 250 75 39 3.2 1.8
38000 -48.3 -54.9 245 73 38 2.8 1.5 | -48.2 -54.8 245 75 38 3.4 1.8
36000 -46.6 -51.9 240 73 38 2.9 1.6 | -46.2 -51.2 235 75 39 3.4 1.9
34000 -42.5 -44.5 235 69 36 8.6 4.7 | -41.9 -43.4 230 73 37 8.6 4.7
32000 -37.3 -35.1 230 64 33 8.7 4.7 | -36.7 -34.1 230 70 36 8.7 4.8
30000 -32.2 -26.0 230 60 31 8.5 4.7 | -31.7 -25.1 225 64 33 8.3 4.5
29000 -29.6 -21.3 230 59 30 8.6 4.7 | -29.2 -20.6 225 60 31 8.3 4.6
28000 -27.1 -16.8 230 57 29 8.7 4.8 | -26.8 -16.2 225 57 29 8.4 4.6
27000 -24.8 -12.6 230 55 28 7.1 3.9 | -24.6 -12.3 225 53 27 6.8 3.7
26000 -22.2 -8.0 230 51 26 7.2 3.9 | -22.1 -7.8 225 50 26 6.8 3.7
25000 -20.1 -4.2 230 48 25 7.2 4.0 | -20.1 -4.2 225 47 24 6.8 3.8
24000 -18.2 -0.8 230 45 23 6.0 3.3 | -18.1 -0.6 225 45 23 6.5 3.6
23000 -16.4 2.5 230 42 22 6.1 3.3 | -16.2 2.8 230 43 22 6.5 3.6
22000 -14.6 5.7 230 39 20 6.1 3.3 | -14.3 6.3 230 41 21 6.6 3.6
21000 -12.8 9.0 230 36 19 6.1 3.3 | -12.5 9.5 230 39 20 5.7 3.1
20000 -11.1 12.0 230 33 17 6.1 3.3 | -10.9 12.4 225 36 18 5.7 3.1
19500 -10.2 13.6 225 32 16 6.0 3.3 | -10.1 13.8 225 34 18 5.8 3.2
19000 -9.3 15.3 225 30 16 5.6 3.0 | -9.2 15.4 225 33 17 6.1 3.3
18500 -8.6 16.5 225 30 15 5.1 2.8 | -8.3 17.1 225 31 16 6.5 3.6
18000 -7.8 18.0 225 29 15 5.1 2.8 | -7.4 18.7 225 30 15 6.6 3.6
17500 -7.1 19.2 225 28 14 4.7 2.6 | -6.5 20.3 220 28 14 5.5 3.0
17000 -6.5 20.3 230 27 14 4.7 2.6 | -5.7 21.7 220 26 14 5.5 3.0
16500 -5.8 21.6 230 26 14 5.2 2.9 | -4.9 23.2 220 25 13 5.0 2.8
16000 -5.0 23.0 235 26 13 5.5 3.0 | -4.2 24.4 220 23 12 4.6 2.5
15500 -4.2 24.4 235 25 13 5.6 3.1 | -3.6 25.5 220 21 11 4.6 2.5
15000 -3.3 26.1 235 25 13 6.1 3.3 | -2.9 26.8 220 20 10 4.8 2.6
14500 -2.5 27.5 240 24 13 6.1 3.3 | -2.2 28.0 220 19 10 4.8 2.6
14000 -1.6 29.1 240 24 12 6.2 3.4 | -1.5 29.3 220 18 9 4.6 2.5
13500 -0.7 30.7 240 24 12 6.2 3.4 | -0.9 30.4 220 17 9 4.6 2.5
13000 0.2 32.4 240 23 12 6.5 3.5 | -0.2 31.6 220 16 8 5.3 2.9
12500 1.1 34.0 235 23 12 6.5 3.6 | 0.6 33.1 220 16 8 5.4 3.0
12000 2.0 35.6 235 23 12 6.4 3.5 | 1.4 34.5 220 15 8 6.0 3.3
11500 2.9 37.2 230 22 11 6.4 3.5 | 2.3 36.1 220 15 8 6.3 3.4
11000 3.9 39.0 225 22 11 6.8 3.7 | 3.2 37.8 215 14 7 6.4 3.5
10500 4.9 40.8 220 21 11 7.0 3.8 | 4.1 39.4 215 14 7 6.4 3.5
10250 5.4 41.7 215 21 11 6.8 3.7 | 4.6 40.3 215 14 7 6.7 3.7
10000 5.9 42.6 210 21 11 6.6 3.6 | 5.1 41.2 210 14 7 6.9 3.8
9750 6.4 43.5 205 21 11 6.9 3.8 | 5.6 42.1 210 14 7 6.8 3.7
9500 6.9 44.4 200 21 11 6.3 3.5 | 6.0 42.8 210 14 7 6.8 3.7
9250 7.4 45.3 200 21 11 8.4 4.6 | 6.5 43.7 205 14 7 6.8 3.8
9000 8.4 47.1 190 21 11 4.7 2.6 | 7.5 45.5 200 15 7 7.0 3.9
8750 8.8 47.8 185 20 10 5.1 2.8 | 8.0 46.4 200 14 7 7.3 4.0
8500 9.2 48.6 180 20 10 5.9 3.2 | 8.5 47.3 195 14 7 6.2 3.4
8250 9.6 49.3 180 20 10 6.6 3.6 | 8.9 48.0 190 15 8 5.3 2.9
8000 10.1 50.2 175 20 10 5.8 3.2 | 9.3 48.7 190 16 8 6.6 3.6
7750 10.5 50.9 170 18 9 5.5 3.0 | 9.9 49.8 185 15 8 7.5 4.1
7500 10.9 51.6 165 17 9 5.7 3.2 | 10.3 50.5 180 14 7 4.7 2.6
7250 11.3 52.3 165 18 9 5.8 3.2 | 10.5 50.9 170 15 8 2.4 1.3
7000 11.8 53.2 165 17 9 7.1 3.9 | 10.8 51.4 165 15 8 7.3 4.0
6750 12.3 54.1 155 15 8 7.6 4.2 | 11.5 52.7 165 13 7 9.8 5.4
6500 12.8 55.0 150 14 7 6.9 3.8 | 12.1 53.8 160 12 6 8.1 4.5
6250 13.3 55.9 150 13 7 6.8 3.7 | 12.7 54.9 155 13 6 7.9 4.3
6000 13.8 56.8 145 12 6 6.9 3.8 | 13.3 55.9 155 13 7 8.9 4.9
5750 14.3 57.7 145 9 4 7.1 3.9 | 14.1 57.4 155 10 5 13.7 7.5
5500 14.8 58.6 130 7 4 6.1 3.3 | 15.4 59.7 150 9 5 23.6 13.0
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
09/28/2026 AT 1500 MDT | 09/28/2026 AT 1800 MDT
|
CAPE... +154.4 LI... 0.0 | CAPE... +133.2 LI... +0.1
CINH... -2.9 K INDEX... +25.9 | CINH... -1.9 K INDEX... +26.1
|
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 -61.7 -79.1 245 42 22 2.5 1.4 | -60.9 -77.6 250 49 25 2.8 1.5
45000 -57.1 -70.8 245 60 31 4.9 2.7 | -56.3 -69.3 245 69 35 4.0 2.2
40000 -49.4 -56.9 245 74 38 2.9 1.6 | -50.0 -58.0 240 73 38 3.7 2.0
38000 -47.6 -53.7 235 73 37 3.1 1.7 | -47.7 -53.9 230 70 36 3.8 2.1
36000 -45.8 -50.4 225 73 37 3.2 1.7 | -45.4 -49.7 220 68 35 3.8 2.1
34000 -41.4 -42.5 220 71 37 9.0 4.9 | -41.0 -41.8 220 67 35 9.1 5.0
32000 -36.0 -32.8 220 69 35 9.1 5.0 | -35.5 -31.9 215 67 34 9.1 5.0
30000 -30.9 -23.6 220 65 33 8.2 4.5 | -30.6 -23.1 215 65 34 7.6 4.2
29000 -28.5 -19.3 220 63 32 8.2 4.5 | -28.4 -19.1 215 64 33 7.6 4.2
28000 -26.1 -15.0 220 60 31 8.3 4.5 | -26.1 -15.0 220 63 33 7.6 4.2
27000 -23.9 -11.0 220 57 30 6.6 3.6 | -24.1 -11.4 220 60 31 6.5 3.6
26000 -21.5 -6.7 220 53 27 6.6 3.6 | -21.7 -7.1 220 54 28 6.5 3.6
25000 -19.5 -3.1 220 50 26 6.7 3.7 | -19.8 -3.6 220 49 25 6.5 3.6
24000 -17.8 -0.0 225 46 24 5.6 3.1 | -18.0 -0.4 225 44 22 5.7 3.1
23000 -16.1 3.0 230 43 22 5.6 3.1 | -16.3 2.7 225 39 20 5.7 3.1
22000 -14.4 6.1 235 39 20 5.6 3.1 | -14.6 5.7 230 34 17 5.7 3.1
21000 -12.7 9.1 235 36 19 6.1 3.4 | -12.7 9.1 235 30 15 6.5 3.6
20000 -10.9 12.4 240 34 17 6.2 3.4 | -10.8 12.6 235 27 14 6.5 3.6
19500 -10.0 14.0 240 32 17 6.2 3.4 | -9.9 14.2 235 25 13 6.5 3.6
19000 -9.1 15.6 245 31 16 6.1 3.4 | -8.9 16.0 235 23 12 6.3 3.5
18500 -8.2 17.2 245 30 15 6.0 3.3 | -8.1 17.4 235 22 11 5.5 3.0
18000 -7.3 18.9 245 28 14 6.0 3.3 | -7.3 18.9 235 20 10 5.6 3.1
17500 -6.5 20.3 240 27 14 5.8 3.2 | -6.5 20.3 235 18 9 5.4 3.0
17000 -5.7 21.7 240 26 13 5.8 3.2 | -5.7 21.7 235 18 9 5.4 2.9
16500 -4.8 23.4 240 25 13 5.6 3.1 | -5.0 23.0 240 17 9 5.3 2.9
16000 -4.1 24.6 235 24 12 5.2 2.9 | -4.2 24.4 240 16 8 5.2 2.8
15500 -3.3 26.1 235 23 12 5.2 2.9 | -3.5 25.7 240 16 8 5.2 2.9
15000 -2.6 27.3 230 21 11 4.6 2.5 | -2.8 27.0 240 15 8 4.8 2.6
14500 -2.0 28.4 225 20 10 4.7 2.6 | -2.1 28.2 235 15 8 4.9 2.7
14000 -1.3 29.7 220 19 10 4.6 2.5 | -1.4 29.5 235 14 7 4.9 2.7
13500 -0.7 30.7 215 18 9 4.5 2.5 | -0.7 30.7 230 14 7 4.9 2.7
13000 -0.0 32.0 210 17 9 5.2 2.8 | -0.0 32.0 225 14 7 5.1 2.8
12500 0.8 33.4 210 16 8 5.4 3.0 | 0.7 33.3 220 15 7 5.2 2.9
12000 1.6 34.9 205 16 8 5.9 3.2 | 1.5 34.7 215 15 8 5.7 3.1
11500 2.4 36.3 200 16 8 6.1 3.4 | 2.4 36.3 210 16 8 6.1 3.4
11000 3.3 37.9 195 15 8 5.7 3.2 | 3.2 37.8 200 16 8 6.2 3.4
10500 4.1 39.4 190 15 8 5.2 2.9 | 4.1 39.4 200 16 8 6.2 3.4
10250 4.5 40.1 190 15 8 6.2 3.4 | 4.6 40.3 195 16 8 6.6 3.6
10000 5.0 41.0 185 14 7 6.7 3.7 | 5.1 41.2 190 17 9 6.6 3.6
9750 5.4 41.7 185 14 7 6.2 3.4 | 5.5 41.9 190 16 8 6.3 3.4
9500 5.9 42.6 180 14 7 5.9 3.2 | 5.9 42.6 185 16 8 6.1 3.4
9250 6.3 43.3 175 13 7 7.6 4.1 | 6.9 44.4 185 16 8 6.3 3.5
9000 7.4 45.3 170 14 7 6.5 3.5 | 7.3 45.1 180 15 8 5.3 2.9
8750 7.9 46.2 170 13 7 6.9 3.8 | 7.7 45.9 175 14 7 5.5 3.0
8500 8.4 47.1 170 12 6 6.6 3.6 | 8.0 46.4 175 14 7 5.5 3.0
8250 8.8 47.8 165 12 6 6.7 3.7 | 8.5 47.3 170 14 7 6.2 3.4
8000 9.3 48.7 165 12 6 7.1 3.9 | 8.9 48.0 170 14 7 6.7 3.7
7750 9.8 49.6 165 11 6 7.7 4.2 | 9.4 48.9 170 13 7 7.0 3.9
7500 10.3 50.5 165 10 5 6.1 3.3 | 9.9 49.8 165 12 6 6.1 3.4
7250 10.7 51.3 160 10 5 4.4 2.4 | 10.3 50.5 165 12 6 5.0 2.7
7000 11.1 52.0 155 10 5 7.1 3.9 | 10.7 51.3 160 12 6 7.4 4.0
6750 11.7 53.1 155 9 4 8.7 4.8 | 11.3 52.3 155 11 6 9.0 4.9
6500 12.3 54.1 150 8 4 8.3 4.5 | 11.9 53.4 150 10 5 6.7 3.7
6250 12.9 55.2 150 7 4 8.4 4.6 | 12.2 54.0 150 9 5 5.0 2.7
6000 13.5 56.3 145 7 4 8.4 4.6 | 12.6 54.7 145 8 4 7.8 4.3
5750 14.2 57.6 145 6 3 11.8 6.5 | 13.4 56.1 140 7 4 12.0 6.6
5500 15.5 59.9 140 5 3 29.9 16.4 | 14.0 57.2 140 5 3 0.4 0.2
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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