841
UXUS97 KGJT 181306
SRGGJT
SOARING FORECAST
NATIONAL WEATHER SERVICE GRAND JUNCTION, COLORADO
706 AM MDT TUESDAY, AUGUST 18, 2026
THIS FORECAST IS FOR TUESDAY, AUGUST 18, 2026:
IF THE TRIGGER TEMPERATURE OF 85.5 F/29.7 C IS REACHED...THEN
THERMAL SOARING INDEX....................... EXCELLENT
MAXIMUM RATE OF LIFT........................ 1534 FT/MIN (7.8 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 19854 FT MSL (14245 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 97.0 F/36.6 C
TIME OF TRIGGER TEMPERATURE.................... 1045 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................. 17022 FT MSL (11413 FT AGL)
THERMAL SOARING OUTLOOK FOR WEDNESDAY 08/19.... EXCELLENT
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 06:30:30 / 20:05:22 MDT
TOTAL POSSIBLE SUNSHINE........... 13 HR 34 MIN 52 SEC (814 MIN 52 SEC)
ALTITUDE OF SUN AT 13:17:56 MDT... 63.49 DEGREES
UPPER AIR DATA FROM RAWINSONDE OBSERVATION TAKEN ON 08/18/2026 AT 0600 MDT
FREEZING LEVEL.................. 16430 FT MSL (10821 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 17197 FT MSL (11588 FT AGL)
LIFTED CONDENSATION LEVEL....... 18554 FT MSL (12945 FT AGL)
LIFTED INDEX.................... -3.2
K INDEX......................... +29.5
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 -64.9 -84.8 300 30 15 0.1 0.0 M M M M M
45000 -61.9 -79.4 300 36 19 5.5 3.0 M M M M M
40000 -53.1 -63.6 300 42 22 8.2 4.5 M M M M M
38000 -48.2 -54.8 300 40 20 8.2 4.5 M M M M M
36000 -43.3 -45.9 300 37 19 8.2 4.5 M M M M M
34000 -37.7 -35.9 295 34 18 8.2 4.5 M M M M M
32000 -32.8 -27.0 290 32 16 8.1 4.5 M M M M M
30000 -28.4 -19.1 290 31 16 7.4 4.1 46.5 115.7 7.9 M M
29000 -26.2 -15.2 290 30 16 7.4 4.1 45.6 114.2 7.3 M M
28000 -24.0 -11.2 290 30 15 6.8 3.7 44.8 112.6 6.7 M M
27000 -22.0 -7.6 290 29 15 6.9 3.8 43.6 110.4 5.8 M M
26000 -19.9 -3.8 285 28 14 6.9 3.8 42.5 108.5 5.0 M M
25000 -17.9 -0.2 285 27 14 7.0 3.8 41.6 106.9 4.3 M M
24000 -15.8 3.6 285 26 13 7.0 3.8 40.5 104.8 3.3 M M
23000 -13.8 7.2 285 25 13 7.0 3.8 39.5 103.0 2.5 M M
22000 -11.7 10.9 285 24 12 7.2 3.9 38.6 101.4 1.7 M M
21000 -9.6 14.7 285 23 12 7.3 4.0 37.6 99.7 0.9 M M
20000 -6.9 19.6 290 22 11 7.3 4.0 36.6 97.8 0.0 M M
19500 -5.8 21.6 290 22 11 6.4 3.5 36.1 97.1 -0.4 1290 6.6
19000 -5.0 23.0 290 22 11 6.2 3.4 35.5 95.9 -1.0 1250 6.3
18500 -4.1 24.6 290 22 11 6.2 3.4 34.9 94.8 -1.6 1209 6.1
18000 -3.2 26.2 285 22 11 7.2 3.9 34.4 93.9 -2.1 1166 5.9
17500 -2.2 28.0 285 21 11 7.1 3.9 33.9 93.0 -2.6 1122 5.7
17000 -1.2 29.8 285 21 11 7.9 4.3 33.5 92.3 -3.1 1077 5.5
16500 -0.0 32.0 285 19 10 8.2 4.5 33.2 91.8 -3.4 1027 5.2
16000 1.2 34.2 285 18 9 8.4 4.6 33.0 91.4 -3.7 977 5.0
15500 2.4 36.3 285 17 9 8.9 4.9 32.8 91.0 -3.9 924 4.7
15000 3.7 38.7 285 16 8 8.9 4.9 32.7 90.8 -4.1 870 4.4
14500 5.1 41.2 290 15 8 9.4 5.1 32.6 90.6 -4.2 815 4.1
14000 6.5 43.7 290 15 8 9.3 5.1 32.5 90.5 -4.3 759 3.9
13500 7.8 46.0 290 14 7 9.3 5.1 32.4 90.4 -4.4 703 3.6
13000 9.2 48.6 295 14 7 9.3 5.1 32.4 90.3 -4.5 647 3.3
12500 10.6 51.1 295 13 7 9.2 5.0 32.3 90.1 -4.6 591 3.0
12000 11.9 53.4 295 12 6 9.0 4.9 32.2 89.9 -4.8 536 2.7
11500 13.3 55.9 295 11 6 8.3 4.6 32.1 89.7 -4.9 481 2.4
11000 14.4 57.9 300 9 5 7.2 3.9 31.7 89.1 -5.3 433 2.2
10500 15.7 60.3 300 8 4 9.9 5.4 31.6 88.8 -5.4 379 1.9
10250 16.3 61.3 295 7 4 7.7 4.2 31.5 88.7 -5.6 353 1.8
10000 16.9 62.4 300 6 3 6.9 3.8 31.3 88.3 -5.8 329 1.7
9750 17.4 63.3 300 5 3 7.8 4.3 31.1 88.0 -6.0 306 1.6
9500 17.9 64.2 300 5 2 5.0 2.8 30.9 87.6 -6.2 282 1.4
9250 18.2 64.8 300 4 2 4.8 2.6 30.4 86.8 -6.6 266 1.4
9000 18.7 65.7 300 3 2 7.3 4.0 30.2 86.4 -6.9 243 1.2
8750 19.2 66.6 300 2 1 6.9 3.8 30.0 85.9 -7.1 221 1.1
8500 19.8 67.6 295 1 1 5.8 3.2 29.8 85.6 -7.3 198 1.0
8250 20.1 68.2 000 0 0 4.6 2.5 29.4 84.9 -7.7 179 0.9
8000 20.5 68.9 110 1 0 5.1 2.8 29.0 84.2 -8.1 161 0.8
7750 20.9 69.6 110 1 1 5.0 2.7 28.6 83.5 -8.5 143 0.7
7500 21.2 70.2 110 2 1 4.1 2.2 28.3 82.9 -8.9 125 0.6
7250 21.4 70.5 110 3 1 2.8 1.5 27.8 82.0 -9.4 110 0.6
7000 21.6 70.9 110 3 2 2.1 1.2 27.2 81.0 -9.9 98 0.5
6750 21.7 71.1 105 4 2 -0.1 -0.1 26.6 79.8 -10.6 88 0.4
6500 21.5 70.7 105 4 2 -3.2 -1.7 25.7 78.2 -11.5 85 0.4
6250 21.2 70.2 095 5 2 -5.8 -3.2 24.6 76.3 -12.6 89 0.5
6000 20.9 69.6 095 5 3 2.1 1.2 23.6 74.5 -13.7 90 0.5
5750 21.2 70.2 090 5 3 -1.7 -0.9 23.2 73.7 -14.2 74 0.4
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 * * * * * *
08/18/2026 AT 0900 MDT | 08/18/2026 AT 1200 MDT
|
CAPE... 0.0 LI... -0.2 | CAPE... +3.2 LI... +0.4
CINH... -0.2 K INDEX... +25.9 | CINH... -1.6 K INDEX... +24.3
|
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 -64.8 -84.6 290 34 18 -0.1 -0.1 | -64.6 -84.3 285 31 16 0.0 0.0
45000 -62.2 -80.0 285 41 21 5.3 2.9 | -61.9 -79.4 280 39 20 5.1 2.8
40000 -53.6 -64.5 275 34 17 8.2 4.5 | -53.5 -64.3 275 34 17 8.1 4.5
38000 -48.7 -55.7 275 31 16 8.2 4.5 | -48.1 -54.6 270 31 16 8.1 4.4
36000 -43.1 -45.6 275 29 15 8.3 4.6 | -43.2 -45.8 265 29 15 8.1 4.5
34000 -38.1 -36.6 275 28 14 8.3 4.6 | -38.3 -36.9 265 28 14 8.1 4.5
32000 -33.1 -27.6 270 28 14 8.7 4.8 | -33.5 -28.3 270 27 14 8.8 4.8
30000 -28.3 -18.9 275 28 14 8.1 4.4 | -28.5 -19.3 275 26 14 8.4 4.6
29000 -25.9 -14.6 275 28 14 8.1 4.4 | -26.0 -14.8 275 26 14 8.4 4.6
28000 -23.6 -10.5 275 28 14 6.8 3.7 | -23.5 -10.3 280 26 14 7.6 4.1
27000 -21.6 -6.9 275 28 14 6.9 3.8 | -21.3 -6.3 280 26 13 7.6 4.2
26000 -19.5 -3.1 275 27 14 6.9 3.8 | -19.0 -2.2 275 26 13 7.6 4.2
25000 -17.5 0.5 275 27 14 7.0 3.9 | -16.7 1.9 275 25 13 7.0 3.9
24000 -15.3 4.5 275 27 14 7.1 3.9 | -14.8 5.4 280 24 13 6.6 3.6
23000 -13.1 8.4 275 26 14 7.2 3.9 | -12.4 9.7 280 23 12 6.6 3.6
22000 -10.6 12.9 275 25 13 5.0 2.8 | -10.5 13.1 280 22 11 5.6 3.1
21000 -9.1 15.6 270 22 12 5.3 2.9 | -8.8 16.2 275 21 11 5.7 3.1
20000 -7.6 18.3 265 20 10 5.4 3.0 | -7.1 19.2 265 19 10 5.7 3.1
19500 -6.8 19.8 260 19 10 5.8 3.2 | -6.2 20.8 265 19 10 5.2 2.9
19000 -5.9 21.4 260 17 9 6.0 3.3 | -5.5 22.1 260 19 10 5.1 2.8
18500 -5.1 22.8 255 16 8 6.1 3.4 | -4.8 23.4 255 18 9 5.1 2.8
18000 -4.2 24.4 255 16 8 7.1 3.9 | -3.9 25.0 250 18 9 7.3 4.0
17500 -3.2 26.2 250 15 8 7.1 3.9 | -2.9 26.8 250 18 9 7.2 3.9
17000 -2.2 28.0 250 15 8 7.9 4.3 | -1.9 28.6 245 18 9 7.7 4.2
16500 -1.0 30.2 250 16 8 8.3 4.5 | -0.8 30.6 245 18 9 8.0 4.4
16000 0.2 32.4 250 16 8 8.5 4.6 | 0.4 32.7 245 18 9 8.1 4.5
15500 1.5 34.7 250 17 9 9.1 5.0 | 1.6 34.9 245 18 9 8.7 4.8
15000 2.8 37.0 250 18 9 9.0 4.9 | 2.8 37.0 245 18 9 8.7 4.7
14500 4.2 39.6 250 19 10 9.4 5.2 | 4.1 39.4 250 18 9 9.3 5.1
14000 5.5 41.9 255 20 10 9.4 5.2 | 5.5 41.9 250 18 9 9.2 5.1
13500 6.9 44.4 255 20 10 9.3 5.1 | 6.8 44.2 250 18 9 9.4 5.2
13000 8.3 46.9 255 20 10 9.3 5.1 | 8.2 46.8 250 18 9 9.4 5.2
12500 9.7 49.5 255 21 11 9.3 5.1 | 9.6 49.3 255 17 9 9.4 5.2
12000 11.0 51.8 255 20 10 9.3 5.1 | 11.0 51.8 255 17 9 9.4 5.2
11500 12.4 54.3 255 20 10 9.1 5.0 | 12.4 54.3 255 16 8 9.3 5.1
11000 13.7 56.7 255 19 10 8.7 4.8 | 13.8 56.8 255 15 8 9.1 5.0
10500 15.0 59.0 255 18 9 7.1 3.9 | 15.2 59.4 255 14 7 7.4 4.0
10250 15.5 59.9 255 18 9 7.1 3.9 | 15.6 60.1 260 14 7 7.8 4.3
10000 16.1 61.0 250 17 9 9.0 4.9 | 16.4 61.5 260 14 7 10.5 5.8
9750 16.8 62.2 250 16 8 8.7 4.7 | 17.1 62.8 260 13 7 9.9 5.4
9500 17.4 63.3 250 16 8 8.1 4.5 | 17.9 64.2 260 13 6 9.6 5.3
9250 18.0 64.4 250 15 8 7.2 3.9 | 18.5 65.3 260 12 6 8.9 4.9
9000 18.5 65.3 250 14 7 6.7 3.7 | 19.2 66.6 260 12 6 8.6 4.7
8750 19.0 66.2 245 13 7 6.6 3.6 | 19.9 67.8 260 11 6 8.8 4.8
8500 19.5 67.1 240 12 6 5.8 3.2 | 20.5 68.9 260 11 6 7.7 4.2
8250 19.9 67.8 240 11 6 4.6 2.5 | 21.0 69.8 260 10 5 5.5 3.0
8000 20.8 69.4 230 9 5 6.7 3.7 | 22.3 72.1 260 9 5 11.8 6.5
7750 21.3 70.3 215 8 4 5.0 2.7 | 23.1 73.6 260 9 4 9.0 4.9
7500 21.6 70.9 210 8 4 3.6 2.0 | 23.7 74.7 265 8 4 7.0 3.9
7250 21.9 71.4 205 7 4 4.9 2.7 | 24.3 75.7 270 8 4 9.5 5.2
7000 22.4 72.3 195 7 4 6.7 3.7 | 25.1 77.2 265 7 4 12.7 7.0
6750 22.9 73.2 185 7 4 6.1 3.3 | 26.0 78.8 265 7 4 11.1 6.1
6500 23.3 73.9 175 7 3 4.8 2.6 | 26.8 80.2 265 7 4 9.9 5.4
6250 23.7 74.7 165 6 3 6.4 3.5 | 27.5 81.5 270 7 3 9.1 5.0
6000 24.3 75.7 165 5 3 10.3 5.7 | 28.3 82.9 270 6 3 15.9 8.7
5750 25.2 77.4 155 5 3 13.0 7.1 | 30.1 86.2 270 6 3 30.9 17.0
5500 26.1 79.0 145 5 2 9.4 5.2 | 31.9 89.4 280 6 3 4.9 2.7
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
08/18/2026 AT 1500 MDT | 08/18/2026 AT 1800 MDT
|
CAPE... +0.9 LI... +0.4 | CAPE... +0.1 LI... +0.5
CINH... -3.7 K INDEX... +20.9 | CINH... -6.6 K INDEX... +22.4
|
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 -65.2 -85.4 285 30 15 -0.5 -0.3 | -65.0 -85.0 290 30 15 -0.6 -0.4
45000 -62.6 -80.7 290 37 19 5.8 3.2 | -62.6 -80.7 295 37 19 5.8 3.2
40000 -53.3 -63.9 280 35 18 8.1 4.5 | -53.2 -63.8 285 38 20 8.3 4.6
38000 -48.4 -55.1 275 34 17 8.1 4.5 | -47.6 -53.7 285 36 19 8.3 4.6
36000 -43.0 -45.4 270 33 17 8.2 4.5 | -42.7 -44.9 285 35 18 8.0 4.4
34000 -38.0 -36.4 270 31 16 8.2 4.5 | -37.9 -36.2 280 34 17 7.9 4.4
32000 -33.1 -27.6 270 30 15 8.5 4.7 | -33.1 -27.6 280 32 17 8.5 4.6
30000 -28.4 -19.1 270 27 14 7.9 4.3 | -28.5 -19.3 275 30 15 7.8 4.3
29000 -26.1 -15.0 270 26 13 7.9 4.3 | -26.2 -15.2 275 28 15 7.8 4.3
28000 -23.8 -10.8 270 25 13 7.5 4.1 | -23.9 -11.0 275 27 14 7.5 4.1
27000 -21.6 -6.9 275 24 12 7.5 4.1 | -21.7 -7.1 275 26 13 7.5 4.1
26000 -19.3 -2.7 280 23 12 7.5 4.1 | -19.4 -2.9 275 24 13 7.5 4.1
25000 -17.1 1.2 280 22 12 7.1 3.9 | -17.2 1.0 275 23 12 7.1 3.9
24000 -15.0 5.0 280 22 11 6.9 3.8 | -15.2 4.6 280 22 11 6.8 3.7
23000 -12.5 9.5 280 21 11 6.9 3.8 | -12.7 9.1 280 20 10 6.8 3.7
22000 -10.5 13.1 280 20 10 6.2 3.4 | -10.8 12.6 280 19 10 6.6 3.6
21000 -8.7 16.3 275 18 9 6.3 3.5 | -8.8 16.2 275 17 9 6.6 3.6
20000 -6.9 19.6 270 17 9 6.4 3.5 | -6.9 19.6 275 16 8 6.6 3.6
19500 -6.0 21.2 270 16 8 6.8 3.7 | -5.9 21.4 270 16 8 7.2 4.0
19000 -4.9 23.2 265 16 8 6.9 3.8 | -4.8 23.4 275 15 8 7.5 4.1
18500 -3.8 25.2 260 16 8 7.0 3.8 | -3.7 25.3 275 15 8 7.5 4.1
18000 -2.8 27.0 260 16 8 7.0 3.8 | -2.6 27.3 275 15 8 8.1 4.4
17500 -1.8 28.8 255 16 8 7.0 3.8 | -1.4 29.5 275 15 7 8.1 4.4
17000 -0.7 30.7 255 16 8 7.8 4.3 | -0.3 31.5 270 14 7 8.3 4.6
16500 0.4 32.7 250 16 8 8.2 4.5 | 1.0 33.8 270 14 7 8.5 4.6
16000 1.6 34.9 250 16 8 8.3 4.6 | 2.2 36.0 270 14 7 8.5 4.7
15500 2.9 37.2 250 16 8 8.9 4.9 | 3.5 38.3 270 14 7 8.9 4.9
15000 4.2 39.6 250 16 8 8.8 4.8 | 4.8 40.6 270 14 7 8.8 4.8
14500 5.5 41.9 250 16 8 9.1 5.0 | 6.2 43.2 270 15 8 9.2 5.0
14000 6.9 44.4 250 16 8 9.1 5.0 | 7.5 45.5 265 15 8 9.2 5.0
13500 8.2 46.8 250 16 8 9.2 5.1 | 8.9 48.0 265 15 8 9.3 5.1
13000 9.6 49.3 255 16 8 9.3 5.1 | 10.3 50.5 265 15 8 9.4 5.1
12500 10.9 51.6 255 16 8 9.3 5.1 | 11.7 53.1 265 15 8 9.4 5.2
12000 12.3 54.1 255 16 8 9.2 5.1 | 13.1 55.6 265 15 8 9.4 5.2
11500 13.7 56.7 255 16 8 9.3 5.1 | 14.5 58.1 265 15 8 9.4 5.2
11000 15.0 59.0 260 16 8 9.2 5.0 | 15.9 60.6 265 15 8 9.3 5.1
10500 16.4 61.5 260 16 8 7.1 3.9 | 17.3 63.1 265 15 8 7.0 3.9
10250 16.9 62.4 260 16 8 7.9 4.3 | 17.7 63.9 265 15 8 7.7 4.2
10000 17.6 63.7 260 16 8 11.2 6.2 | 18.5 65.3 265 15 8 11.1 6.1
9750 18.4 65.1 260 16 8 10.5 5.8 | 19.3 66.7 265 15 8 10.3 5.6
9500 19.2 66.6 260 15 8 10.0 5.5 | 20.0 68.0 265 15 8 10.1 5.5
9250 19.9 67.8 265 16 8 9.4 5.2 | 20.8 69.4 265 15 8 9.3 5.1
9000 20.6 69.1 265 16 8 9.9 5.4 | 21.4 70.5 265 15 8 9.2 5.1
8750 21.4 70.5 265 16 8 10.2 5.6 | 22.1 71.8 265 14 7 9.4 5.2
8500 22.1 71.8 265 15 8 9.4 5.1 | 23.4 74.1 265 14 7 7.6 4.2
8250 22.8 73.0 265 16 8 7.9 4.3 | 24.0 75.2 265 14 7 9.4 5.1
8000 24.3 75.7 265 15 8 12.4 6.8 | 24.8 76.6 265 14 7 11.4 6.3
7750 25.1 77.2 265 15 8 9.8 5.4 | 25.6 78.1 265 14 7 9.7 5.3
7500 25.7 78.3 270 15 8 7.3 4.0 | 26.3 79.3 265 14 7 8.0 4.4
7250 26.3 79.3 270 16 8 9.7 5.3 | 26.9 80.4 270 14 7 9.2 5.1
7000 27.2 81.0 270 15 8 13.1 7.2 | 27.7 81.9 270 14 7 11.6 6.4
6750 28.2 82.8 270 15 8 11.5 6.3 | 28.6 83.5 265 13 7 10.9 6.0
6500 28.9 84.0 270 15 8 10.2 5.6 | 29.3 84.7 270 13 7 9.9 5.4
6250 29.7 85.5 270 15 8 8.9 4.9 | 30.1 86.2 270 13 7 9.6 5.2
6000 30.4 86.7 270 14 7 14.6 8.0 | 30.8 87.4 270 13 6 11.1 6.1
5750 32.1 89.8 270 13 7 31.8 17.4 | 31.8 89.2 270 11 6 18.2 10.0
5500 34.3 93.7 275 13 7 15.8 8.6 | 33.4 92.1 270 11 5 20.0 11.0
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
________________________________________________________________________________
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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