824  
UXUS97 KGJT 201233  
SRGGJT  
 
SOARING FORECAST  
NATIONAL WEATHER SERVICE GRAND JUNCTION, COLORADO  
0633 MDT FRIDAY, OCTOBER 20, 2017  
 
THIS FORECAST IS FOR FRIDAY, OCTOBER 20, 2017:  
 
IF THE TRIGGER TEMPERATURE OF 71.7 F/22.1 C IS REACHED...THEN  
THERMAL SOARING INDEX....................... EXCELLENT  
MAXIMUM RATE OF LIFT........................ 994 FT/MIN (5.1 M/S)  
MAXIMUM HEIGHT OF THERMALS.................. 13590 FT MSL (8751 FT AGL)  
 
FORECAST MAXIMUM TEMPERATURE................... 74.0 F/23.8 C  
TIME OF TRIGGER TEMPERATURE.................... 1315 MDT  
TIME OF OVERDEVELOPMENT........................ 1800 MDT  
MIDDLE/HIGH CLOUDS DURING SOARING WINDOW....... NONE  
SURFACE WINDS DURING SOARING WINDOW............ 20 MPH OR LESS  
HEIGHT OF THE -3 THERMAL INDEX................. 7473 FT MSL (2634 FT AGL)  
THERMAL SOARING OUTLOOK FOR SATURDAY 10/21..... GOOD  
 
WAVE SOARING INDEX............................. NOT AVAILABLE  
 
REMARKS...  
 
SUNRISE/SUNSET.................... 07:29:18 / 18:29:22 MDT  
TOTAL POSSIBLE SUNSHINE........... 11 HR 0 MIN 4 SEC (660 MIN 4 SEC)  
ALTITUDE OF SUN AT 12:58:55 MDT... 40.29 DEGREES  
 
UPPER AIR DATA FROM RAWINSONDE OBSERVATION TAKEN ON 10/20/2017 AT 0600 MDT  
 
FREEZING LEVEL.................. 12549 FT MSL (7710 FT AGL)  
CONVECTIVE CONDENSATION LEVEL... 14355 FT MSL (9516 FT AGL)  
LIFTED CONDENSATION LEVEL....... 14073 FT MSL (9234 FT AGL)  
LIFTED INDEX.................... +1.0  
K INDEX......................... +25.4  
 
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 -63.2 -81.8 260 31 16 -5.9 -3.2 93.4 200.1 40.1 M M  
45000 -64.6 -84.3 300 22 11 5.5 3.0 65.2 149.3 25.8 M M  
40000 -56.7 -70.1 310 36 18 -0.9 -0.5 54.7 130.4 20.7 M M  
38000 -52.4 -62.3 310 43 22 8.5 4.7 52.4 126.3 19.7 M M  
36000 -48.8 -55.8 315 40 21 7.3 4.0 49.1 120.4 18.0 M M  
34000 -44.0 -47.2 315 38 20 8.9 4.9 47.5 117.5 17.3 M M  
32000 -39.3 -38.7 310 39 20 6.5 3.6 46.0 114.9 16.6 M M  
30000 -36.4 -33.5 280 22 11 3.7 2.0 41.1 106.0 13.4 M M  
29000 -35.3 -31.5 285 20 10 6.1 3.3 38.8 101.8 11.8 M M  
28000 -32.8 -27.0 290 19 10 8.4 4.6 38.2 100.8 11.5 M M  
27000 -30.6 -23.1 275 20 10 3.8 2.1 37.2 99.0 10.8 M M  
26000 -28.5 -19.3 260 23 12 8.4 4.6 36.3 97.3 10.2 M M  
25000 -26.0 -14.8 250 26 13 8.4 4.6 35.8 96.4 9.9 M M  
24000 -23.8 -10.8 255 25 13 4.9 2.7 34.9 94.9 9.3 M M  
23000 -21.5 -6.7 255 27 14 8.9 4.9 34.1 93.4 8.7 M M  
22000 -18.9 -2.0 260 29 15 9.2 5.0 33.8 92.9 8.5 M M  
21000 -17.3 0.9 260 31 16 2.1 1.1 32.4 90.2 7.3 M M  
20000 -16.5 2.3 260 33 17 9.8 5.4 29.8 85.7 5.2 M M  
19500 -15.7 3.7 245 30 16 8.3 4.6 29.1 84.4 4.6 M M  
19000 -14.6 5.7 225 31 16 3.0 1.6 28.8 83.9 4.4 M M  
18500 -13.7 7.3 220 30 16 9.6 5.3 28.1 82.6 3.8 M M  
18000 -12.4 9.7 220 31 16 9.0 4.9 28.0 82.5 3.7 M M  
17500 -11.3 11.7 215 33 17 6.9 3.8 27.6 81.7 3.3 M M  
17000 -9.6 14.7 215 33 17 7.9 4.3 27.1 80.8 2.9 M M  
16500 -8.4 16.9 215 31 16 7.8 4.3 26.8 80.2 2.6 M M  
16000 -7.3 18.9 215 29 15 7.3 4.0 26.5 79.6 2.3 M M  
15500 -6.5 20.3 215 30 15 5.9 3.3 25.8 78.4 1.6 M M  
15000 -5.4 22.3 215 30 15 6.9 3.8 25.3 77.6 1.2 M M  
14500 -4.4 24.1 225 28 15 7.0 3.9 24.9 76.8 0.8 M M  
14000 -3.4 25.9 235 28 14 7.0 3.8 24.4 75.9 0.3 M M  
13500 -2.4 27.7 235 28 14 7.8 4.3 24.0 75.1 -0.2 781 4.0  
13000 -1.1 30.0 240 28 14 9.2 5.1 23.8 74.9 -0.3 727 3.7  
12500 0.3 32.5 240 28 14 9.2 5.0 23.7 74.7 -0.4 671 3.4  
12000 1.6 34.9 240 28 14 9.2 5.0 23.7 74.6 -0.4 615 3.1  
11500 3.0 37.4 240 26 14 9.2 5.0 23.6 74.4 -0.5 559 2.8  
11000 4.4 39.9 245 25 13 9.2 5.0 23.5 74.3 -0.6 504 2.6  
10500 5.7 42.3 235 25 13 9.2 5.0 23.4 74.1 -0.7 448 2.3  
10250 6.4 43.5 235 25 13 9.2 5.1 23.3 74.0 -0.8 420 2.1  
10000 7.1 44.8 230 25 13 9.0 4.9 23.3 73.9 -0.9 392 2.0  
9750 7.7 45.9 225 25 13 8.7 4.8 23.2 73.8 -0.9 365 1.9  
9500 8.4 47.1 225 24 13 8.8 4.8 23.1 73.6 -1.0 338 1.7  
9250 9.0 48.2 225 24 12 8.8 4.8 23.1 73.5 -1.1 312 1.6  
9000 9.7 49.5 220 24 12 8.7 4.8 23.0 73.4 -1.2 285 1.4  
8750 10.3 50.5 215 25 13 8.9 4.9 22.9 73.2 -1.2 258 1.3  
8500 11.0 51.8 215 26 13 8.3 4.5 22.8 73.1 -1.3 231 1.2  
8250 11.5 52.7 210 27 14 5.0 2.8 22.6 72.7 -1.5 208 1.1  
8000 11.8 53.2 210 28 14 3.5 1.9 22.2 71.9 -2.0 193 1.0  
7750 12.0 53.6 210 26 14 3.5 1.9 21.7 71.0 -2.5 177 0.9  
7500 12.3 54.1 210 24 13 4.9 2.7 21.2 70.2 -2.9 162 0.8  
7250 12.8 55.0 210 22 12 7.5 4.1 21.0 69.8 -3.2 140 0.7  
7000 13.4 56.1 210 20 11 7.8 4.3 20.8 69.5 -3.3 115 0.6  
6750 13.9 57.0 210 18 9 7.7 4.2 20.7 69.2 -3.5 91 0.5  
6500 14.5 58.1 205 15 8 7.8 4.3 20.5 69.0 -3.6 66 0.3  
6250 15.1 59.2 200 13 7 7.7 4.2 20.4 68.7 -3.8 41 0.2  
6000 15.7 60.3 195 11 5 7.8 4.3 20.2 68.4 -4.0 16 0.1  
5750 16.3 61.3 190 9 4 7.4 4.0 20.1 68.2 -4.1 M M  
5500 16.8 62.2 175 7 4 9.1 5.0 19.9 67.9 -4.3 M M  
5250 17.4 63.3 160 6 3 0.6 0.3 19.7 67.5 -4.5 M M  
5000 16.7 62.1 135 5 3 -18.6 -10.2 18.3 64.9 -5.9 M M  
 
* * * * * * NUMERICAL WEATHER PREDICTION MODEL FORECAST DATA VALID * * * * * *  
 
10/20/2017 AT 0900 MDT | 10/20/2017 AT 1200 MDT  
|  
K INDEX... +19.7 LI... +0.9 | K INDEX... +9.7 LI... +0.1  
CAPE... +2.2 CIN... -3.2 | CAPE... +20.3 CIN... -9.0  
|  
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 -62.1 -79.8 245 31 16 -0.8 -0.5 | -61.3 -78.3 240 39 20 -0.0 -0.0  
45000 -62.9 -81.2 240 30 16 3.0 1.7 | -61.1 -78.0 230 53 27 2.0 1.1  
40000 -58.3 -72.9 270 49 25 2.4 1.3 | -58.2 -72.8 235 58 30 1.8 1.0  
38000 -54.0 -65.2 270 47 24 8.0 4.4 | -55.1 -67.2 235 58 30 6.2 3.4  
36000 -49.2 -56.6 270 42 22 8.0 4.4 | -51.4 -60.5 235 58 30 6.2 3.4  
34000 -44.4 -47.9 270 39 20 7.9 4.3 | -47.3 -53.1 240 56 29 8.0 4.4  
32000 -39.7 -39.5 270 36 18 7.9 4.3 | -42.5 -44.5 245 55 28 8.0 4.4  
30000 -35.2 -31.4 270 32 17 6.9 3.8 | -37.7 -35.9 250 54 28 8.1 4.4  
29000 -33.1 -27.6 265 31 16 7.6 3.8 | -35.3 -31.5 255 54 28 8.1 4.4  
28000 -30.5 -22.9 265 29 15 6.9 3.8 | -32.9 -27.2 255 54 28 8.1 4.4  
27000 -28.5 -19.3 260 28 14 6.1 3.4 | -29.9 -21.8 260 53 27 7.9 4.3  
26000 -26.7 -16.1 255 29 15 6.1 3.4 | -27.5 -17.5 255 51 26 7.9 4.3  
25000 -24.8 -12.6 250 30 15 6.1 3.4 | -25.1 -13.2 255 48 25 7.9 4.4  
24000 -23.0 -9.4 250 31 16 5.4 3.0 | -22.8 -9.0 255 46 24 7.3 4.0  
23000 -21.4 -6.5 250 33 17 5.4 3.0 | -20.6 -5.1 250 45 23 7.3 4.0  
22000 -19.8 -3.6 250 34 18 5.4 3.0 | -18.5 -1.3 245 44 23 7.3 4.0  
21000 -18.0 -0.4 250 36 18 7.5 4.1 | -16.5 2.3 245 43 22 4.1 2.3  
20000 -15.9 3.4 245 36 18 7.3 4.0 | -15.2 4.6 240 43 22 4.5 2.5  
19500 -14.8 5.4 245 36 18 7.3 4.0 | -14.5 5.9 240 43 22 4.5 2.5  
19000 -13.7 7.3 245 36 18 7.4 4.1 | -13.8 7.2 240 43 22 4.5 2.5  
18500 -12.6 9.3 245 36 18 6.1 3.4 | -13.1 8.4 235 43 22 5.6 3.1  
18000 -11.8 10.8 245 36 19 5.9 3.2 | -12.2 10.0 240 44 22 6.0 3.3  
17500 -10.9 12.4 245 37 19 5.9 3.2 | -11.3 11.7 240 44 22 6.1 3.3  
17000 -10.1 13.8 240 37 19 5.8 3.2 | -10.4 13.3 240 44 23 6.2 3.4  
16500 -9.2 15.4 240 37 19 5.8 3.2 | -9.5 14.9 240 44 23 6.2 3.4  
16000 -8.4 16.9 235 37 19 5.6 3.1 | -8.6 16.5 240 44 23 6.1 3.4  
15500 -7.6 18.3 235 37 19 5.7 3.1 | -7.7 18.1 240 44 23 6.2 3.4  
15000 -6.8 19.8 230 37 19 6.5 3.6 | -6.8 19.8 240 44 23 6.3 3.5  
14500 -5.8 21.6 230 37 19 7.0 3.9 | -5.8 21.6 240 43 22 6.5 3.6  
14000 -4.8 23.4 230 37 19 7.4 4.1 | -4.9 23.2 240 43 22 6.7 3.7  
13500 -3.2 26.2 230 35 18 8.0 4.4 | -3.9 25.0 240 42 22 7.4 4.0  
13000 -2.0 28.4 230 34 18 9.2 5.0 | -2.4 27.7 235 40 21 8.0 4.4  
12500 -0.6 30.9 230 33 17 9.5 5.2 | -1.2 29.8 235 39 20 8.4 4.6  
12000 0.8 33.4 230 32 17 8.8 4.8 | -0.1 31.8 235 37 19 9.1 5.0  
11500 2.0 35.6 230 31 16 8.3 4.6 | 1.3 34.3 235 37 19 9.4 5.2  
11000 3.2 37.8 230 30 15 8.6 4.7 | 2.7 36.9 230 37 19 9.1 5.0  
10500 4.5 40.1 230 28 14 8.6 4.7 | 4.0 39.2 230 36 18 8.7 4.8  
10250 5.2 41.4 230 27 14 10.3 5.6 | 4.6 40.3 230 35 18 9.6 5.3  
10000 6.0 42.8 230 26 13 9.8 5.4 | 5.3 41.5 230 34 18 9.6 5.3  
9750 6.6 43.9 230 25 13 8.1 4.4 | 6.0 42.8 230 33 17 8.8 4.8  
9500 7.3 45.1 230 23 12 8.8 4.8 | 6.7 44.1 225 31 16 9.3 5.1  
9250 7.9 46.2 230 21 11 7.8 4.3 | 7.3 45.1 225 29 15 8.0 4.4  
9000 8.4 47.1 235 21 11 7.2 4.0 | 7.9 46.2 225 28 15 8.1 4.5  
8750 9.0 48.2 230 20 10 7.6 4.2 | 8.5 47.3 225 26 14 9.6 5.3  
8500 9.5 49.1 230 19 10 7.3 4.0 | 9.2 48.6 220 24 13 8.6 4.7  
8250 10.1 50.2 230 18 9 8.1 4.4 | 9.9 49.8 220 23 12 11.2 6.1  
8000 10.7 51.3 230 18 9 6.8 3.8 | 10.8 51.4 220 22 11 11.0 6.0  
7750 11.1 52.0 230 18 9 5.0 2.7 | 11.5 52.7 220 21 11 8.4 4.6  
7500 11.4 52.5 225 18 9 5.9 3.2 | 12.1 53.8 220 21 11 8.9 4.9  
7250 11.8 53.2 225 19 10 4.0 2.2 | 12.8 55.0 220 21 11 9.6 5.3  
7000 12.0 53.6 215 19 10 1.5 0.8 | 13.6 56.5 215 20 10 10.5 5.7  
6750 12.1 53.8 205 18 9 1.2 0.7 | 14.3 57.7 215 20 10 9.9 5.4  
6500 12.1 53.8 195 18 9 -0.1 -0.0 | 15.0 59.0 215 19 10 9.9 5.4  
6250 12.0 53.6 190 16 8 -4.8 -2.7 | 15.8 60.4 215 19 10 10.5 5.8  
6000 11.5 52.7 180 14 7 -6.5 -3.6 | 16.6 61.9 215 18 9 10.9 6.0  
5750 11.1 52.0 170 11 5 -4.9 -2.7 | 17.4 63.3 215 17 9 9.8 5.4  
5500 10.9 51.6 150 7 4 -0.6 -0.3 | 18.1 64.6 215 15 8 11.2 6.2  
5250 11.1 52.0 150 7 3 7.7 4.2 | 19.1 66.4 215 15 8 15.6 8.6  
5000 M M M M M M M | M M M M M M M  
 
10/20/2017 AT 1500 MDT | 10/20/2017 AT 1800 MDT  
|  
K INDEX... +22.3 LI... +0.5 | K INDEX... +25.1 LI... -1.6  
CAPE... +11.3 CIN... -3.4 | CAPE... +62.4 CIN... -29.9  
|  
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 -58.6 -73.5 240 42 22 1.5 0.8 | -58.0 -72.4 240 42 22 1.0 0.5  
45000 -56.5 -69.7 240 61 31 -0.6 -0.3 | -56.5 -69.7 255 55 28 -0.1 -0.0  
40000 -57.2 -71.0 235 49 25 -0.4 -0.2 | -56.5 -69.7 245 63 33 -0.0 -0.0  
38000 -55.5 -67.9 240 52 27 4.6 2.5 | -55.5 -67.9 245 69 35 3.1 1.7  
36000 -52.7 -62.9 250 60 31 4.6 2.5 | -53.6 -64.5 250 76 39 3.1 1.7  
34000 -49.4 -56.9 255 67 34 7.9 4.3 | -51.1 -60.0 250 80 41 8.8 4.8  
32000 -44.0 -47.2 250 67 34 8.0 4.4 | -45.3 -49.5 240 71 36 8.5 4.7  
30000 -39.0 -38.2 250 66 34 8.7 4.8 | -40.3 -40.5 235 67 35 8.4 4.6  
29000 -36.4 -33.5 250 65 33 8.7 4.8 | -37.8 -36.0 240 69 36 8.3 4.6  
28000 -33.8 -28.8 250 64 33 8.7 4.8 | -35.3 -31.5 240 71 37 8.3 4.6  
27000 -31.3 -24.3 250 63 32 7.4 4.0 | -32.8 -27.0 240 74 38 7.5 4.1  
26000 -29.1 -20.4 245 63 32 7.4 4.1 | -30.7 -23.3 245 72 37 7.0 3.9  
25000 -26.9 -16.4 245 62 32 7.4 4.1 | -28.6 -19.5 245 71 36 7.0 3.9  
24000 -24.6 -12.3 245 62 32 7.4 4.0 | -26.5 -15.7 245 69 36 6.8 3.7  
23000 -22.4 -8.3 245 61 31 7.3 4.0 | -24.8 -12.6 245 65 33 5.7 3.2  
22000 -20.2 -4.4 245 59 30 7.3 4.0 | -23.1 -9.6 245 60 31 5.8 3.2  
21000 -18.1 -0.6 245 57 29 6.0 3.3 | -21.3 -6.3 240 55 28 6.1 3.3  
20000 -16.4 2.5 245 55 28 5.7 3.1 | -19.5 -3.1 240 52 27 6.5 3.6  
19500 -15.6 3.9 245 54 28 5.7 3.2 | -18.5 -1.3 235 51 26 6.5 3.6  
19000 -14.7 5.5 240 52 27 5.7 3.1 | -17.1 1.2 235 49 25 6.4 3.5  
18500 -13.9 7.0 240 51 26 5.2 2.8 | -16.1 3.0 230 47 24 8.7 4.8  
18000 -13.2 8.2 240 50 26 4.6 2.5 | -14.8 5.4 230 45 23 9.0 4.9  
17500 -12.6 9.3 240 48 25 4.4 2.4 | -13.5 7.7 230 43 22 9.0 4.9  
17000 -11.8 10.8 240 47 24 6.3 3.4 | -12.2 10.0 230 42 22 8.9 4.9  
16500 -10.9 12.4 240 46 24 6.1 3.4 | -10.9 12.4 230 41 21 9.0 4.9  
16000 -10.0 14.0 240 45 23 7.2 4.0 | -9.6 14.7 230 40 21 8.0 4.4  
15500 -8.9 16.0 240 44 22 7.7 4.3 | -8.4 16.9 230 39 20 8.0 4.4  
15000 -7.2 19.0 235 41 21 9.0 4.9 | -7.2 19.0 230 38 19 8.8 4.8  
14500 -5.9 21.4 235 39 20 9.0 4.9 | -5.9 21.4 230 37 19 9.1 5.0  
14000 -4.5 23.9 235 37 19 9.4 5.2 | -4.5 23.9 225 36 19 9.3 5.1  
13500 -3.1 26.4 230 36 18 9.5 5.2 | -3.1 26.4 225 35 18 9.5 5.2  
13000 -1.7 28.9 230 35 18 9.5 5.2 | -1.7 28.9 230 34 18 9.4 5.2  
12500 -0.3 31.5 230 33 17 9.4 5.2 | -0.3 31.5 230 34 17 9.1 5.0  
12000 1.1 34.0 230 31 16 9.4 5.2 | 1.0 33.8 230 33 17 9.1 5.0  
11500 2.5 36.5 230 29 15 9.5 5.2 | 2.4 36.3 230 32 17 8.9 4.9  
11000 3.9 39.0 230 28 14 9.6 5.3 | 3.7 38.7 230 31 16 9.0 4.9  
10500 5.4 41.7 230 27 14 10.0 5.5 | 5.1 41.2 235 30 16 9.7 5.3  
10250 6.1 43.0 230 27 14 9.3 5.1 | 5.8 42.4 235 30 15 9.2 5.0  
10000 6.8 44.2 230 26 13 9.6 5.2 | 6.5 43.7 235 29 15 8.8 4.8  
9750 7.6 45.7 230 26 13 10.2 5.6 | 7.2 45.0 235 29 15 9.2 5.0  
9500 8.3 46.9 230 25 13 10.5 5.8 | 7.8 46.0 235 28 14 9.4 5.2  
9250 9.1 48.4 230 25 13 9.1 5.0 | 8.5 47.3 235 27 14 9.0 4.9  
9000 9.7 49.5 230 24 13 8.8 4.8 | 9.1 48.4 235 26 14 7.5 4.1  
8750 10.5 50.9 230 24 12 10.2 5.6 | 9.7 49.5 240 26 13 8.7 4.8  
8500 11.2 52.2 230 24 12 9.5 5.2 | 10.4 50.7 240 25 13 10.0 5.5  
8250 12.0 53.6 230 23 12 11.6 6.4 | 11.2 52.2 240 24 12 10.4 5.7  
8000 12.9 55.2 230 23 12 11.0 6.1 | 11.9 53.4 245 23 12 7.7 4.2  
7750 13.6 56.5 230 23 12 8.7 4.8 | 12.4 54.3 245 22 12 7.1 3.9  
7500 14.2 57.6 230 22 12 9.1 5.0 | 13.0 55.4 245 22 11 9.5 5.2  
7250 14.9 58.8 230 22 11 9.7 5.3 | 13.7 56.7 245 21 11 9.1 5.0  
7000 15.7 60.3 235 22 11 10.4 5.7 | 14.4 57.9 250 20 10 8.4 4.6  
6750 16.4 61.5 235 21 11 9.8 5.4 | 15.0 59.0 250 19 10 8.2 4.5  
6500 17.2 63.0 235 21 11 9.5 5.2 | 15.6 60.1 250 18 9 9.1 5.0  
6250 17.9 64.2 235 20 10 10.1 5.6 | 16.3 61.3 255 16 8 8.7 4.8  
6000 18.7 65.7 235 19 10 10.8 5.9 | 16.9 62.4 255 15 8 8.2 4.5  
5750 19.5 67.1 235 18 9 10.4 5.7 | 17.5 63.5 255 14 7 6.7 3.7  
5500 20.3 68.5 235 16 8 11.1 6.1 | 17.9 64.2 255 12 6 4.9 2.7  
5250 21.2 70.2 235 16 8 13.6 7.5 | 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.  
 
CIN (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.  
 
042613  
 
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