582
UXUS97 KGJT 171306
SRGGJT
SOARING FORECAST
NATIONAL WEATHER SERVICE GRAND JUNCTION, COLORADO
706 AM MDT SUNDAY, MAY 17, 2026
THIS FORECAST IS FOR SUNDAY, MAY 17, 2026:
IF THE TRIGGER TEMPERATURE OF 53.6 F/12.0 C IS REACHED...THEN
THERMAL SOARING INDEX....................... EXCELLENT
MAXIMUM RATE OF LIFT........................ 1386 FT/MIN (7.0 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 21415 FT MSL (15806 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 74.0 F/23.8 C
TIME OF TRIGGER TEMPERATURE.................... 0730 MDT
TIME OF OVERDEVELOPMENT........................ 1200 MDT
MIDDLE/HIGH CLOUDS DURING SOARING WINDOW....... BROKEN/OVERCAST THIN MIDDLE
SURFACE WINDS DURING SOARING WINDOW............ 20 MPH OR LESS
HEIGHT OF THE -3 THERMAL INDEX................. 17418 FT MSL (11809 FT AGL)
THERMAL SOARING OUTLOOK FOR MONDAY 05/18....... GOOD
WAVE SOARING INDEX............................. NOT AVAILABLE
REMARKS...
SUNRISE/SUNSET.................... 05:58:59 / 20:22:07 MDT
TOTAL POSSIBLE SUNSHINE........... 14 HR 23 MIN 8 SEC (863 MIN 8 SEC)
ALTITUDE OF SUN AT 13:10:33 MDT... 70.21 DEGREES
UPPER AIR DATA FROM RAWINSONDE OBSERVATION TAKEN ON 05/17/2026 AT 0600 MDT
FREEZING LEVEL.................. 9653 FT MSL (4044 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 9749 FT MSL (4140 FT AGL)
LIFTED CONDENSATION LEVEL....... 14268 FT MSL (8659 FT AGL)
LIFTED INDEX.................... -7.6
K INDEX......................... +26.2
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 -54.7 -66.5 245 31 16 1.5 0.8 M M M M M
45000 -52.3 -62.1 255 33 17 2.3 1.3 M M M M M
40000 -48.6 -55.5 250 43 22 2.5 1.4 M M M M M
38000 -47.4 -53.3 245 46 24 1.1 0.6 M M M M M
36000 -46.8 -52.2 235 49 25 1.1 0.6 M M M M M
34000 -46.1 -51.0 225 53 27 1.4 0.8 M M M M M
32000 -45.2 -49.4 220 52 27 1.4 0.8 M M M M M
30000 -44.2 -47.6 210 52 27 5.4 3.0 30.8 87.5 5.7 M M
29000 -42.3 -44.1 210 49 25 6.5 3.6 29.4 84.9 4.6 M M
28000 -40.3 -40.5 205 46 23 6.5 3.6 28.1 82.6 3.7 M M
27000 -38.4 -37.1 205 42 22 6.4 3.5 26.9 80.5 2.8 M M
26000 -36.1 -33.0 205 41 21 8.6 4.7 26.2 79.1 2.2 M M
25000 -33.5 -28.3 205 41 21 8.6 4.7 25.7 78.3 1.8 M M
24000 -30.9 -23.6 205 41 21 8.6 4.7 25.3 77.6 1.6 M M
23000 -28.5 -19.3 205 42 21 7.7 4.2 24.8 76.6 1.1 M M
22000 -26.2 -15.2 205 43 22 7.7 4.2 24.0 75.1 0.4 M M
21000 -24.0 -11.2 205 44 23 7.7 4.2 23.3 73.9 -0.2 1354 6.9
20000 -21.7 -7.1 205 44 23 7.4 4.0 22.5 72.4 -0.9 1258 6.4
19500 -20.7 -5.3 205 44 23 7.4 4.0 22.0 71.6 -1.3 1211 6.2
19000 -19.0 -2.2 205 44 23 7.4 4.0 21.4 70.5 -1.9 1140 5.8
18500 -18.0 -0.4 205 44 23 7.4 4.0 21.0 69.9 -2.2 1093 5.6
18000 -16.9 1.6 205 43 22 7.4 4.1 20.6 69.2 -2.6 1045 5.3
17500 -15.8 3.6 205 43 22 7.4 4.1 20.2 68.4 -3.0 998 5.1
17000 -14.7 5.5 205 42 22 7.4 4.1 19.9 67.7 -3.4 950 4.8
16500 -13.6 7.5 205 42 21 7.4 4.1 19.4 67.0 -3.8 903 4.6
16000 -12.5 9.5 205 41 21 7.5 4.1 19.1 66.3 -4.2 856 4.3
15500 -11.4 11.5 205 40 20 7.6 4.1 18.7 65.6 -4.6 808 4.1
15000 -10.3 13.5 210 38 20 7.6 4.2 18.3 65.0 -5.0 760 3.9
14500 -9.3 15.3 205 38 19 7.0 3.8 17.9 64.2 -5.4 714 3.6
14000 -8.2 17.2 205 37 19 7.0 3.9 17.5 63.4 -5.9 668 3.4
13500 -7.2 19.0 205 37 19 7.1 3.9 17.0 62.6 -6.3 623 3.2
13000 -6.2 20.8 205 37 19 7.1 3.9 16.6 61.8 -6.8 578 2.9
12500 -5.2 22.6 205 38 19 6.6 3.6 16.1 61.0 -7.3 533 2.7
12000 -4.3 24.3 200 39 20 6.5 3.6 15.6 60.1 -7.9 490 2.5
11500 -3.3 26.1 200 40 21 6.4 3.5 15.1 59.2 -8.4 447 2.3
11000 -2.4 27.7 200 40 21 6.4 3.5 14.5 58.2 -9.0 405 2.1
10500 -1.5 29.3 195 40 20 6.5 3.6 14.1 57.3 -9.6 362 1.8
10250 -1.0 30.2 195 39 20 5.8 3.2 13.8 56.8 -9.9 342 1.7
10000 -0.6 30.9 195 38 20 5.4 2.9 13.4 56.2 -10.3 322 1.6
9750 -0.2 31.6 195 37 19 5.6 3.1 13.1 55.6 -10.6 303 1.5
9500 0.2 32.4 195 36 19 7.0 3.9 12.8 55.1 -10.9 283 1.4
9250 0.7 33.3 195 35 18 6.3 3.4 12.6 54.7 -11.2 260 1.3
9000 1.1 34.0 190 33 17 4.5 2.5 12.2 54.0 -11.6 242 1.2
8750 1.4 34.5 190 31 16 5.7 3.1 11.9 53.4 -12.0 223 1.1
8500 1.9 35.4 190 29 15 7.5 4.1 11.6 52.9 -12.3 202 1.0
8250 2.5 36.5 190 27 14 7.3 4.0 11.5 52.7 -12.5 177 0.9
8000 2.9 37.2 190 26 13 5.4 3.0 11.2 52.2 -12.8 156 0.8
7750 3.3 37.9 185 24 12 6.2 3.4 10.9 51.6 -13.1 137 0.7
7500 3.9 39.0 185 22 12 7.5 4.1 10.7 51.2 -13.4 114 0.6
7250 4.4 39.9 185 21 11 7.3 4.0 10.5 50.9 -13.6 91 0.5
7000 4.9 40.8 180 19 10 7.2 4.0 10.3 50.6 -13.8 67 0.3
6750 5.4 41.7 180 18 9 6.5 3.6 10.1 50.2 -14.1 45 0.2
6500 5.9 42.6 175 16 8 5.9 3.3 9.8 49.7 -14.4 24 0.1
6250 6.3 43.3 170 15 8 6.7 3.7 9.6 49.2 -14.7 3 0.0
6000 6.8 44.2 165 13 7 7.0 3.9 9.4 48.9 -15.0 M M
5750 7.3 45.1 160 11 6 5.3 2.9 9.1 48.4 -15.3 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 * * * * * *
05/17/2026 AT 0900 MDT | 05/17/2026 AT 1200 MDT
|
CAPE... +255.6 LI... -1.7 | CAPE... +607.8 LI... -3.1
CINH... -69.2 K INDEX... +22.0 | CINH... -7.6 K INDEX... +29.0
|
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 -54.7 -66.5 230 44 23 1.5 0.8 | -54.6 -66.3 235 46 24 0.4 0.2
45000 -52.5 -62.5 240 51 26 -0.3 -0.1 | -54.0 -65.2 235 55 28 0.1 0.0
40000 -53.8 -64.8 235 52 27 -0.9 -0.5 | -54.1 -65.4 230 62 32 -0.0 -0.0
38000 -53.2 -63.8 235 53 28 3.1 1.7 | -53.5 -64.3 230 64 33 1.9 1.1
36000 -51.4 -60.5 235 56 29 3.1 1.7 | -52.3 -62.1 235 65 33 1.9 1.1
34000 -49.2 -56.6 230 59 30 4.3 2.4 | -51.0 -59.8 240 66 34 4.6 2.5
32000 -46.6 -51.9 230 58 30 4.3 2.3 | -48.2 -54.8 245 66 34 4.8 2.6
30000 -43.8 -46.8 230 56 29 6.8 3.7 | -45.1 -49.2 250 65 33 8.1 4.4
29000 -41.9 -43.4 230 55 28 6.7 3.7 | -42.7 -44.9 250 61 31 7.9 4.3
28000 -39.9 -39.8 235 53 28 6.7 3.7 | -40.4 -40.7 250 56 29 7.9 4.3
27000 -37.9 -36.2 235 52 27 6.8 3.7 | -37.4 -35.3 245 51 26 8.0 4.4
26000 -35.6 -32.1 235 50 26 8.0 4.4 | -35.0 -31.0 245 51 26 8.1 4.4
25000 -33.2 -27.8 235 48 25 8.0 4.4 | -32.6 -26.7 245 51 26 8.1 4.4
24000 -30.8 -23.4 235 46 24 8.0 4.4 | -30.2 -22.4 240 51 26 8.0 4.4
23000 -28.5 -19.3 235 43 22 7.5 4.1 | -28.0 -18.4 240 49 25 7.2 4.0
22000 -25.7 -14.3 240 40 20 7.5 4.1 | -25.8 -14.4 240 46 24 7.3 4.0
21000 -23.5 -10.3 240 37 19 7.8 4.3 | -23.7 -10.7 240 43 22 7.9 4.3
20000 -21.2 -6.2 245 36 18 7.9 4.3 | -21.2 -6.2 235 41 21 8.2 4.5
19500 -20.0 -4.0 245 35 18 7.9 4.3 | -20.0 -4.0 235 41 21 8.2 4.5
19000 -18.8 -1.8 245 34 18 7.9 4.3 | -18.8 -1.8 235 40 20 8.3 4.5
18500 -17.7 0.1 245 34 17 8.2 4.5 | -17.6 0.3 230 39 20 8.3 4.6
18000 -16.4 2.5 245 33 17 8.4 4.6 | -16.3 2.7 230 38 20 8.4 4.6
17500 -15.2 4.6 245 32 16 8.5 4.6 | -15.1 4.8 230 38 20 8.5 4.7
17000 -14.0 6.8 245 31 16 8.2 4.5 | -13.9 7.0 230 38 19 8.2 4.5
16500 -12.8 9.0 245 30 16 8.2 4.5 | -12.7 9.1 230 37 19 8.3 4.5
16000 -11.5 11.3 245 29 15 8.3 4.6 | -11.4 11.5 230 36 19 8.3 4.6
15500 -10.3 13.5 240 28 14 8.3 4.6 | -10.2 13.6 230 35 18 8.4 4.6
15000 -9.1 15.6 240 27 14 8.1 4.4 | -9.0 15.8 225 34 18 8.4 4.6
14500 -7.9 17.8 240 25 13 7.8 4.3 | -7.8 18.0 225 33 17 8.4 4.6
14000 -6.8 19.8 240 23 12 7.7 4.2 | -6.5 20.3 225 32 16 8.4 4.6
13500 -5.7 21.7 235 21 11 7.2 3.9 | -5.3 22.5 225 30 15 8.1 4.4
13000 -4.7 23.5 235 18 9 7.2 3.9 | -4.1 24.6 220 28 14 8.2 4.5
12500 -3.6 25.5 230 16 8 8.0 4.4 | -3.0 26.6 220 26 13 8.1 4.4
12000 -2.4 27.7 225 14 7 7.9 4.3 | -1.8 28.8 220 24 12 8.1 4.4
11500 -1.2 29.8 225 12 6 8.2 4.5 | -0.6 30.9 220 22 11 8.5 4.7
11000 -0.0 32.0 220 11 6 8.4 4.6 | 0.7 33.3 220 20 10 8.7 4.8
10500 1.1 34.0 220 9 5 6.4 3.5 | 1.8 35.2 220 17 9 5.5 3.0
10250 1.5 34.7 220 9 5 7.5 4.1 | 2.2 36.0 220 16 8 7.9 4.3
10000 2.2 36.0 215 8 4 9.8 5.4 | 3.0 37.4 220 15 8 12.2 6.7
9750 2.9 37.2 215 8 4 8.2 4.5 | 3.8 38.8 220 14 7 9.6 5.3
9500 3.3 37.9 210 7 4 6.3 3.5 | 4.4 39.9 220 13 7 6.7 3.7
9250 3.8 38.8 205 6 3 6.5 3.6 | 4.9 40.8 220 11 6 6.8 3.7
9000 4.3 39.7 205 6 3 7.7 4.2 | 6.3 43.3 225 10 5 10.6 5.8
8750 4.9 40.8 195 5 3 7.4 4.0 | 6.9 44.4 225 9 5 7.9 4.3
8500 5.3 41.5 190 5 2 5.7 3.1 | 7.6 45.7 230 8 4 7.9 4.3
8250 6.2 43.2 175 4 2 5.1 2.8 | 8.2 46.8 235 7 4 10.7 5.9
8000 6.5 43.7 170 4 2 5.1 2.8 | 9.1 48.4 230 8 4 11.8 6.5
7750 6.9 44.4 160 3 2 5.9 3.2 | 9.9 49.8 235 7 4 9.1 5.0
7500 7.3 45.1 145 3 2 6.7 3.7 | 10.6 51.1 235 7 4 10.7 5.9
7250 7.7 45.9 130 3 2 2.8 1.6 | 11.3 52.3 235 6 3 6.8 3.8
7000 7.8 46.0 120 3 2 4.9 2.7 | 11.7 53.1 245 5 3 8.0 4.4
6750 8.5 47.3 115 3 2 10.4 5.7 | 12.6 54.7 245 5 3 12.4 6.8
6500 9.1 48.4 110 3 1 8.8 4.8 | 13.5 56.3 245 5 3 11.5 6.3
6250 9.8 49.6 100 3 2 8.9 4.9 | 14.3 57.7 245 5 3 9.5 5.2
6000 10.4 50.7 095 3 2 8.2 4.5 | 15.1 59.2 255 4 2 15.4 8.4
5750 11.1 52.0 100 3 1 13.1 7.2 | 16.8 62.2 260 4 2 31.0 17.0
5500 12.9 55.2 095 3 2 42.6 23.4 | 18.5 65.3 265 4 2 1.5 0.8
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
05/17/2026 AT 1500 MDT | 05/17/2026 AT 1800 MDT
|
CAPE... +538.2 LI... -2.0 | CAPE... +204.6 LI... -0.7
CINH... -14.4 K INDEX... +26.9 | CINH... -78.7 K INDEX... +24.1
|
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 -54.1 -65.4 240 42 22 0.2 0.1 | -53.8 -64.8 240 40 21 0.9 0.5
45000 -53.8 -64.8 240 52 27 0.4 0.2 | -52.4 -62.3 245 53 27 -0.6 -0.3
40000 -53.0 -63.4 240 59 30 0.6 0.3 | -54.7 -66.5 245 63 32 -1.5 -0.8
38000 -53.0 -63.4 240 61 31 -0.9 -0.5 | -55.2 -67.4 245 66 34 -0.1 -0.0
36000 -53.5 -64.3 245 62 32 -0.9 -0.5 | -55.2 -67.4 240 67 34 -0.1 -0.0
34000 -53.3 -63.9 245 63 32 7.3 4.0 | -54.3 -65.7 240 68 35 8.9 4.9
32000 -49.2 -56.6 250 64 33 6.8 3.7 | -49.2 -56.6 240 67 34 8.5 4.7
30000 -44.9 -48.8 250 63 33 8.8 4.8 | -44.1 -47.4 240 66 34 8.5 4.6
29000 -42.3 -44.1 250 61 31 8.7 4.8 | -41.5 -42.7 240 64 33 8.5 4.7
28000 -39.7 -39.5 245 59 30 8.7 4.8 | -39.0 -38.2 240 62 32 8.5 4.7
27000 -37.1 -34.8 245 57 29 8.7 4.8 | -36.4 -33.5 240 60 31 8.5 4.7
26000 -34.5 -30.1 245 54 28 8.6 4.7 | -33.9 -29.0 235 58 30 8.5 4.6
25000 -32.0 -25.6 245 51 26 8.6 4.7 | -31.4 -24.5 235 56 29 8.5 4.6
24000 -29.4 -20.9 245 49 25 8.7 4.8 | -28.9 -20.0 230 54 28 8.5 4.7
23000 -27.0 -16.6 240 46 24 8.0 4.4 | -26.5 -15.7 230 52 27 8.1 4.4
22000 -24.6 -12.3 235 43 22 8.0 4.4 | -24.0 -11.2 225 50 26 8.1 4.5
21000 -21.6 -6.9 230 41 21 7.9 4.3 | -21.1 -6.0 220 48 25 7.8 4.3
20000 -19.3 -2.7 230 40 21 7.9 4.3 | -18.8 -1.8 220 46 24 7.8 4.3
19500 -18.1 -0.6 230 40 20 7.9 4.4 | -17.6 0.3 220 45 23 7.8 4.3
19000 -17.0 1.4 230 39 20 7.9 4.4 | -16.5 2.3 220 45 23 7.8 4.3
18500 -15.8 3.6 230 39 20 7.9 4.3 | -15.3 4.5 220 44 22 7.7 4.2
18000 -14.7 5.5 225 38 20 7.9 4.3 | -14.2 6.4 220 43 22 7.6 4.2
17500 -13.5 7.7 225 38 20 7.9 4.3 | -13.1 8.4 215 42 22 7.7 4.2
17000 -12.3 9.9 225 37 19 8.1 4.5 | -12.0 10.4 215 41 21 7.8 4.3
16500 -11.2 11.8 225 37 19 8.1 4.4 | -10.8 12.6 215 40 20 7.8 4.3
16000 -10.0 14.0 225 36 18 8.4 4.6 | -9.7 14.5 215 39 20 8.4 4.6
15500 -8.7 16.3 225 35 18 8.5 4.7 | -8.4 16.9 215 37 19 8.6 4.7
15000 -7.5 18.5 225 34 18 8.6 4.7 | -7.1 19.2 215 35 18 8.7 4.8
14500 -6.2 20.8 225 33 17 8.7 4.8 | -5.8 21.6 215 34 17 8.9 4.9
14000 -4.9 23.2 225 32 16 8.7 4.8 | -4.5 23.9 220 32 16 8.9 4.9
13500 -3.6 25.5 225 31 16 8.8 4.8 | -3.2 26.2 220 30 15 8.9 4.9
13000 -2.3 27.9 225 29 15 8.9 4.9 | -1.8 28.8 220 28 14 9.0 4.9
12500 -1.1 30.0 225 28 14 8.6 4.7 | -0.6 30.9 220 26 13 8.4 4.6
12000 0.2 32.4 225 27 14 8.7 4.8 | 0.7 33.3 220 23 12 8.5 4.6
11500 1.5 34.7 225 25 13 8.7 4.8 | 1.9 35.4 225 21 11 8.2 4.5
11000 2.8 37.0 225 24 12 8.8 4.9 | 3.1 37.6 225 19 10 8.3 4.6
10500 4.0 39.2 225 22 11 6.8 3.7 | 4.2 39.6 230 17 9 5.5 3.0
10250 4.5 40.1 225 20 10 8.6 4.7 | 4.6 40.3 230 16 8 7.3 4.0
10000 5.2 41.4 225 20 10 10.5 5.8 | 5.2 41.4 235 14 7 9.5 5.2
9750 6.0 42.8 225 20 10 9.4 5.1 | 5.9 42.6 240 13 7 8.2 4.5
9500 6.6 43.9 225 19 10 8.6 4.7 | 6.4 43.5 245 12 6 7.1 3.9
9250 7.2 45.0 225 18 9 8.8 4.8 | 7.0 44.6 250 11 6 7.1 3.9
9000 7.9 46.2 225 17 9 9.7 5.3 | 7.5 45.5 255 10 5 7.8 4.3
8750 8.7 47.7 225 17 9 9.7 5.3 | 8.1 46.6 260 9 5 7.4 4.1
8500 9.4 48.9 225 16 8 9.2 5.0 | 8.6 47.5 270 8 4 6.8 3.7
8250 10.0 50.0 225 15 8 9.2 5.1 | 9.0 48.2 280 8 4 6.3 3.5
8000 11.4 52.5 225 15 8 9.6 5.3 | 10.3 50.5 300 7 3 9.9 5.5
7750 12.1 53.8 225 14 7 9.2 5.1 | 10.9 51.6 305 7 3 8.2 4.5
7500 12.8 55.0 220 14 7 9.8 5.4 | 11.5 52.7 315 7 3 9.4 5.2
7250 13.5 56.3 220 13 7 8.0 4.4 | 12.2 54.0 320 7 3 6.4 3.5
7000 14.1 57.4 225 12 6 8.7 4.8 | 12.6 54.7 320 8 4 7.5 4.1
6750 14.8 58.6 220 12 6 10.9 6.0 | 13.4 56.1 325 8 4 11.1 6.1
6500 15.6 60.1 220 11 6 10.5 5.7 | 14.1 57.4 325 7 4 10.5 5.8
6250 16.4 61.5 220 11 6 10.2 5.6 | 14.9 58.8 330 7 3 9.2 5.1
6000 17.3 63.1 220 10 5 16.3 8.9 | 15.6 60.1 335 8 4 11.4 6.3
5750 18.9 66.0 220 9 4 27.5 15.1 | 16.7 62.1 340 8 4 19.6 10.8
5500 20.5 68.9 220 8 4 7.2 4.0 | 17.9 64.2 340 7 4 3.7 2.0
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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