730
UXUS97 KBOU 151355
SRGBOU
SOARING FORECAST
NATIONAL WEATHER SERVICE DENVER/BOULDER, COLORADO
0755 MDT TUESDAY, SEPTEMBER 15, 2026
THIS FORECAST IS FOR TUESDAY, SEPTEMBER 15, 2026:
IF THE TRIGGER TEMPERATURE OF 66.8 F/19.3 C IS REACHED...THEN
THERMAL SOARING INDEX....................... POOR
MAXIMUM RATE OF LIFT........................ 119 FT/MIN (0.6 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 10370 FT MSL (5014 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 72.0 F/22.7 C
TIME OF TRIGGER TEMPERATURE.................... 1245 MDT
TIME OF OVERDEVELOPMENT........................ 1500 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................. 9282 FT MSL (3925 FT AGL)
THERMAL SOARING OUTLOOK FOR WEDNESDAY 09/16.... EXCELLENT
WAVE SOARING INDEX............................. POOR
WAVE SOARING INDEX TREND (TO 1800 MDT)......... LITTLE TO NO CHANGE
HEIGHT OF STABLE LAYER (12-18K FT MSL)......... 10000 FT MSL (4644 FT AGL)
WEAK PVA/NVA (THROUGH 1800 MDT)................ NEITHER
POTENTIAL HEIGHT OF WAVE....................... 41017 FT MSL (35661 FT AGL)
WAVE SOARING OUTLOOK FOR WEDNESDAY 09/16....... POOR
REMARKS...
SUNRISE/SUNSET.................... 06:40:56 / 19:08:16 MDT
TOTAL POSSIBLE SUNSHINE........... 12 HR 27 MIN 20 SEC (747 MIN 20 SEC)
ALTITUDE OF SUN AT 12:54:36 MDT... 53.01 DEGREES
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 09/15/2026 AT 0600 MDT
FREEZING LEVEL.................. 15346 FT MSL (9990 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 18206 FT MSL (12850 FT AGL)
LIFTED CONDENSATION LEVEL....... 14029 FT MSL (8672 FT AGL)
LIFTED INDEX.................... +5.9
K INDEX......................... +19.5
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 -65.1 -85.2 250 55 28 2.3 1.2 M M M M M
45000 -60.2 -76.4 250 79 41 5.2 2.8 M M M M M
40000 -52.3 -62.1 245 84 43 6.7 3.7 M M M M M
38000 -48.2 -54.8 245 77 39 6.8 3.7 M M M M M
36000 -44.2 -47.6 245 69 35 6.8 3.7 M M M M M
34000 -39.6 -39.3 245 61 31 6.8 3.8 M M M M M
32000 -35.4 -31.7 245 55 28 6.7 3.7 M M M M M
30000 -30.9 -23.6 245 47 24 7.8 4.3 45.3 113.6 17.5 M M
29000 -28.6 -19.5 245 44 23 7.8 4.3 44.6 112.3 17.2 M M
28000 -26.3 -15.3 245 40 21 7.4 4.0 44.0 111.2 16.9 M M
27000 -24.2 -11.6 245 38 20 7.0 3.8 42.8 109.0 16.1 M M
26000 -22.1 -7.8 245 36 18 7.0 3.8 41.7 107.1 15.4 M M
25000 -20.0 -4.0 250 33 17 7.0 3.8 40.8 105.5 14.9 M M
24000 -17.9 -0.2 250 31 16 7.3 4.0 39.8 103.7 14.2 M M
23000 -15.8 3.6 245 29 15 7.3 4.0 38.9 102.0 13.5 M M
22000 -13.7 7.3 245 27 14 7.4 4.0 38.1 100.6 13.0 M M
21000 -11.6 11.1 240 25 13 6.9 3.8 37.1 98.7 12.2 M M
20000 -9.6 14.7 235 23 12 7.0 3.8 36.1 96.9 11.4 M M
19500 -8.6 16.5 230 23 12 7.0 3.8 35.6 96.1 11.0 M M
19000 -7.1 19.2 230 22 11 7.0 3.9 34.9 94.9 10.5 M M
18500 -6.0 21.2 230 21 11 7.1 3.9 34.5 94.0 10.1 M M
18000 -5.0 23.0 235 21 11 6.9 3.8 34.0 93.2 9.7 M M
17500 -4.0 24.8 235 21 11 6.8 3.7 33.5 92.3 9.3 M M
17000 -3.0 26.6 240 20 10 6.8 3.7 33.0 91.4 8.9 M M
16500 -2.1 28.2 245 20 10 6.7 3.7 32.5 90.5 8.4 M M
16000 -1.1 30.0 245 20 10 6.8 3.7 32.0 89.6 8.0 M M
15500 -0.2 31.6 250 20 10 6.1 3.3 31.4 88.6 7.5 M M
15000 0.7 33.3 245 19 10 6.0 3.3 30.8 87.5 6.9 M M
14500 1.5 34.7 245 18 9 5.8 3.2 30.2 86.4 6.4 M M
14000 2.3 36.1 245 17 9 5.6 3.1 29.5 85.1 5.7 M M
13500 3.1 37.6 240 16 8 5.5 3.0 28.8 83.9 5.1 M M
13000 3.9 39.0 235 13 7 5.1 2.8 28.1 82.6 4.4 M M
12500 4.6 40.3 230 10 5 5.0 2.8 27.4 81.2 3.7 M M
12000 5.2 41.4 220 8 4 4.2 2.3 26.5 79.7 2.9 M M
11500 5.9 42.6 200 5 3 4.2 2.3 25.6 78.2 2.1 M M
11000 6.4 43.5 180 3 2 2.9 1.6 24.6 76.4 1.2 M M
10500 7.0 44.6 135 2 1 2.9 1.6 23.6 74.4 0.3 M M
10250 7.2 45.0 100 1 1 1.4 0.8 23.0 73.4 -0.2 313 1.6
10000 7.3 45.1 070 2 1 0.5 0.3 22.3 72.1 -0.9 304 1.5
9750 7.3 45.1 045 3 1 0.8 0.5 21.6 70.8 -1.5 294 1.5
9500 7.4 45.3 035 4 2 0.3 0.2 20.9 69.6 -2.2 285 1.4
9250 7.3 45.1 030 6 3 -1.6 -0.9 20.1 68.1 -3.0 279 1.4
9000 7.2 45.0 035 7 4 -1.4 -0.8 19.2 66.5 -3.9 277 1.4
8750 7.1 44.8 035 9 5 -0.5 -0.3 18.3 65.0 -4.7 273 1.4
8500 7.0 44.6 035 10 5 0.9 0.5 17.6 63.6 -5.5 268 1.4
8250 7.1 44.8 035 11 6 2.8 1.6 17.0 62.6 -6.2 256 1.3
8000 7.3 45.1 035 11 6 3.6 2.0 16.5 61.6 -6.7 243 1.2
7750 7.7 45.9 030 12 6 7.2 4.0 16.1 61.0 -7.1 224 1.1
7500 8.3 46.9 025 11 6 7.0 3.8 16.0 60.8 -7.2 198 1.0
7250 8.8 47.8 015 11 6 4.8 2.7 15.6 60.1 -7.5 177 0.9
7000 9.3 48.7 005 11 6 5.5 3.0 15.3 59.5 -7.7 155 0.8
6750 9.8 49.6 355 11 6 8.8 4.8 15.1 59.1 -7.9 130 0.7
6500 10.7 51.3 355 11 6 9.8 5.4 15.1 59.2 -7.8 98 0.5
6250 11.3 52.3 350 11 6 7.9 4.4 15.0 59.0 -7.9 71 0.4
6000 12.0 53.6 350 11 6 8.4 4.6 14.9 58.8 -8.0 45 0.2
5750 12.6 54.7 345 11 6 8.4 4.6 14.8 58.6 -8.1 18 0.1
5500 13.3 55.9 345 9 5 9.2 5.1 14.7 58.5 -8.2 M M
* * * * * * NUMERICAL WEATHER PREDICTION MODEL FORECAST DATA VALID * * * * * *
09/15/2026 AT 0900 MDT | 09/15/2026 AT 1200 MDT
|
CAPE... +0.2 LI... +1.1 | CAPE... +0.3 LI... +0.6
CINH... 0.0 K INDEX... +21.2 | CINH... -0.0 K INDEX... +22.5
|
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 -65.3 -85.5 250 61 31 2.1 1.2 | -65.8 -86.4 250 64 33 1.7 0.9
45000 -60.7 -77.3 250 80 41 5.2 2.9 | -61.3 -78.3 245 79 40 5.5 3.0
40000 -52.5 -62.5 240 86 44 7.3 4.0 | -52.6 -62.7 235 84 43 7.9 4.3
38000 -48.1 -54.6 240 78 40 7.4 4.0 | -47.9 -54.2 235 79 40 7.9 4.3
36000 -43.7 -46.7 245 69 35 7.4 4.1 | -43.1 -45.6 235 73 38 8.1 4.4
34000 -39.2 -38.6 245 58 30 6.5 3.5 | -38.9 -38.0 240 60 31 6.0 3.3
32000 -35.4 -31.7 245 48 25 6.3 3.5 | -35.2 -31.4 240 48 25 5.7 3.1
30000 -30.9 -23.6 245 43 22 7.6 4.2 | -30.7 -23.3 245 41 21 7.9 4.3
29000 -28.6 -19.5 250 41 21 7.6 4.2 | -28.3 -18.9 250 38 19 7.9 4.3
28000 -26.3 -15.3 250 39 20 7.5 4.1 | -25.9 -14.6 250 35 18 7.9 4.4
27000 -24.1 -11.4 250 37 19 7.4 4.1 | -23.6 -10.5 250 33 17 8.0 4.4
26000 -21.9 -7.4 250 35 18 7.4 4.1 | -21.2 -6.2 250 32 16 8.0 4.4
25000 -19.7 -3.5 250 33 17 7.4 4.1 | -18.8 -1.8 250 30 15 7.9 4.3
24000 -17.5 0.5 245 31 16 7.3 4.0 | -16.8 1.8 245 29 15 6.5 3.6
23000 -15.3 4.5 245 29 15 7.3 4.0 | -14.9 5.2 245 29 15 6.5 3.6
22000 -13.2 8.2 245 28 14 7.2 4.0 | -12.9 8.8 245 29 15 6.5 3.6
21000 -11.3 11.7 240 26 13 6.5 3.6 | -11.1 12.0 240 28 15 6.3 3.5
20000 -9.4 15.1 240 25 13 6.6 3.6 | -9.3 15.3 240 28 14 6.4 3.5
19500 -8.4 16.9 240 24 12 6.7 3.7 | -8.4 16.9 240 27 14 6.4 3.5
19000 -7.1 19.2 235 23 12 6.0 3.3 | -7.0 19.4 245 26 14 6.1 3.4
18500 -6.2 20.8 240 22 11 6.0 3.3 | -6.1 21.0 245 26 13 6.2 3.4
18000 -5.4 22.3 240 22 11 6.4 3.5 | -5.2 22.6 245 25 13 6.0 3.3
17500 -4.4 24.1 240 21 11 6.5 3.6 | -4.4 24.1 250 24 12 6.1 3.3
17000 -3.5 25.7 245 21 11 6.5 3.6 | -3.6 25.5 250 24 12 6.4 3.5
16500 -2.5 27.5 250 21 11 6.6 3.6 | -2.6 27.3 255 23 12 7.4 4.0
16000 -1.6 29.1 250 21 11 6.6 3.6 | -1.5 29.3 255 22 11 7.4 4.0
15500 -0.7 30.7 255 20 10 6.7 3.7 | -0.5 31.1 255 21 11 7.3 4.0
15000 0.3 32.5 255 20 10 6.8 3.7 | 0.6 33.1 260 21 11 7.3 4.0
14500 1.3 34.3 255 19 10 6.9 3.8 | 1.7 35.1 260 20 10 7.5 4.1
14000 2.2 36.0 250 18 9 6.9 3.8 | 2.8 37.0 255 19 10 7.5 4.1
13500 3.2 37.8 245 17 9 6.5 3.6 | 3.8 38.8 255 18 9 7.3 4.0
13000 4.1 39.4 245 16 8 5.9 3.2 | 4.8 40.6 250 18 9 7.0 3.8
12500 4.9 40.8 240 15 8 5.4 3.0 | 5.8 42.4 250 17 9 6.7 3.7
12000 5.5 41.9 235 13 6 3.8 2.1 | 6.7 44.1 245 16 8 6.0 3.3
11500 6.0 42.8 230 10 5 3.5 1.9 | 7.6 45.7 240 15 8 5.2 2.9
11000 6.4 43.5 225 8 4 1.9 1.0 | 8.0 46.4 230 14 7 1.9 1.0
10500 6.8 44.2 215 5 3 2.0 1.1 | 8.3 46.9 225 12 6 1.5 0.8
10250 6.9 44.4 210 4 2 2.0 1.1 | 8.3 46.9 220 11 6 0.1 0.0
10000 7.0 44.6 200 4 2 1.3 0.7 | 8.3 46.9 220 10 5 0.2 0.1
9750 7.1 44.8 170 4 2 0.8 0.5 | 8.3 46.9 210 9 5 0.3 0.2
9500 7.2 45.0 140 4 2 1.2 0.6 | 8.3 46.9 200 8 4 1.0 0.5
9250 7.3 45.1 130 5 3 1.8 1.0 | 8.5 47.3 190 8 4 2.5 1.4
9000 7.4 45.3 120 6 3 1.1 0.6 | 8.6 47.5 180 9 4 2.1 1.2
8750 7.3 45.1 115 6 3 -0.6 -0.3 | 8.7 47.7 165 9 5 1.5 0.8
8500 7.2 45.0 105 6 3 -0.0 -0.0 | 8.8 47.8 155 9 5 1.5 0.8
8250 7.3 45.1 095 6 3 0.6 0.3 | 8.9 48.0 155 9 4 1.1 0.6
8000 7.3 45.1 085 6 3 0.9 0.5 | 9.0 48.2 155 8 4 2.3 1.3
7750 7.5 45.5 070 6 3 3.5 1.9 | 9.3 48.7 150 7 4 6.0 3.3
7500 7.8 46.0 060 6 3 3.7 2.0 | 9.8 49.6 140 8 4 6.5 3.6
7250 8.1 46.6 050 6 3 2.4 1.3 | 10.3 50.5 135 7 4 5.2 2.8
7000 8.3 46.9 035 6 3 2.9 1.6 | 10.7 51.3 125 7 3 6.0 3.3
6750 8.7 47.7 025 6 3 8.3 4.5 | 11.2 52.2 120 7 3 10.0 5.5
6500 9.5 49.1 020 6 3 10.6 5.8 | 12.1 53.8 115 7 3 11.2 6.2
6250 10.2 50.4 015 6 3 8.5 4.7 | 12.8 55.0 115 6 3 9.9 5.4
6000 10.8 51.4 010 5 3 8.3 4.6 | 13.6 56.5 115 6 3 9.4 5.2
5750 11.5 52.7 360 5 3 11.6 6.3 | 14.4 57.9 110 5 3 15.1 8.3
5500 12.7 54.9 005 5 3 19.7 10.8 | 16.0 60.8 110 5 3 27.5 15.1
09/15/2026 AT 1500 MDT | 09/15/2026 AT 1800 MDT
|
CAPE... +9.5 LI... -0.1 | CAPE... +96.7 LI... -1.1
CINH... -46.0 K INDEX... +27.5 | CINH... -29.9 K INDEX... +28.3
|
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 -65.1 -85.2 250 61 32 1.9 1.0 | -64.5 -84.1 250 54 28 1.8 1.0
45000 -60.8 -77.4 245 75 39 4.9 2.7 | -60.3 -76.5 245 71 36 4.9 2.7
40000 -52.9 -63.2 235 79 41 8.0 4.4 | -52.6 -62.7 240 78 40 7.6 4.2
38000 -48.0 -54.4 240 77 39 8.1 4.5 | -47.9 -54.2 235 76 39 7.7 4.2
36000 -43.2 -45.8 240 74 38 8.3 4.6 | -42.7 -44.9 235 74 38 7.3 4.0
34000 -39.0 -38.2 240 62 32 5.7 3.2 | -38.9 -38.0 235 64 33 6.3 3.4
32000 -35.6 -32.1 240 49 25 5.3 2.9 | -35.1 -31.2 240 54 28 6.0 3.3
30000 -30.9 -23.6 240 43 22 8.2 4.5 | -30.5 -22.9 240 48 24 8.0 4.4
29000 -28.4 -19.1 240 40 21 8.2 4.5 | -28.1 -18.6 245 45 23 8.0 4.4
28000 -25.9 -14.6 240 37 19 8.0 4.4 | -25.7 -14.3 245 42 21 7.9 4.3
27000 -23.5 -10.3 240 36 18 8.0 4.4 | -23.3 -9.9 240 40 21 7.9 4.3
26000 -21.2 -6.2 235 34 18 8.0 4.4 | -21.0 -5.8 240 38 20 7.9 4.3
25000 -18.8 -1.8 235 32 17 7.9 4.3 | -18.6 -1.5 235 37 19 7.9 4.3
24000 -16.7 1.9 235 31 16 6.7 3.7 | -16.6 2.1 235 34 18 6.6 3.6
23000 -14.8 5.4 240 30 15 6.8 3.7 | -14.7 5.5 235 32 16 6.7 3.7
22000 -12.8 9.0 240 29 15 6.8 3.7 | -12.8 9.0 240 29 15 6.7 3.7
21000 -11.0 12.2 245 28 14 6.5 3.6 | -11.0 12.2 240 29 15 6.1 3.4
20000 -9.1 15.6 250 27 14 6.6 3.6 | -8.7 16.3 250 29 15 6.2 3.4
19500 -7.7 18.1 250 26 14 6.4 3.5 | -7.9 17.8 250 29 15 6.3 3.4
19000 -6.9 19.6 255 26 14 5.2 2.9 | -6.9 19.6 255 29 15 6.6 3.6
18500 -6.2 20.8 255 26 14 5.2 2.9 | -6.0 21.2 255 28 14 6.6 3.6
18000 -5.4 22.3 255 26 13 6.3 3.5 | -5.0 23.0 255 27 14 6.5 3.6
17500 -4.4 24.1 255 25 13 6.5 3.6 | -4.1 24.6 255 26 13 6.5 3.6
17000 -3.5 25.7 255 25 13 6.7 3.7 | -3.2 26.2 260 24 13 6.7 3.7
16500 -2.5 27.5 255 23 12 7.0 3.9 | -2.2 28.0 260 23 12 7.4 4.1
16000 -1.5 29.3 255 22 11 7.0 3.9 | -1.1 30.0 260 21 11 7.4 4.1
15500 -0.5 31.1 255 21 11 7.1 3.9 | -0.0 32.0 260 19 10 7.8 4.3
15000 0.5 32.9 255 20 10 7.1 3.9 | 1.1 34.0 255 17 9 7.8 4.3
14500 1.6 34.9 255 19 10 7.7 4.2 | 2.2 36.0 255 16 8 7.9 4.4
14000 2.7 36.9 250 17 9 7.9 4.3 | 3.4 38.1 250 15 8 8.0 4.4
13500 3.9 39.0 250 16 8 7.8 4.3 | 4.5 40.1 245 14 7 7.8 4.3
13000 5.0 41.0 245 15 8 7.8 4.3 | 5.6 42.1 235 13 7 7.5 4.1
12500 6.2 43.2 240 14 7 7.5 4.1 | 6.7 44.1 225 13 6 7.3 4.0
12000 7.2 45.0 235 14 7 6.7 3.7 | 7.7 45.9 215 13 6 7.0 3.8
11500 8.2 46.8 225 13 7 6.4 3.5 | 8.7 47.7 205 13 7 6.9 3.8
11000 8.9 48.0 220 12 6 4.5 2.5 | 9.7 49.5 200 13 7 6.2 3.4
10500 9.6 49.3 210 11 6 3.1 1.7 | 10.6 51.1 190 13 7 4.1 2.2
10250 9.7 49.5 205 11 6 1.6 0.9 | 10.8 51.4 190 13 7 2.0 1.1
10000 9.9 49.8 200 11 6 3.7 2.0 | 11.0 51.8 185 13 7 4.7 2.6
9750 10.2 50.4 190 11 6 4.5 2.5 | 11.4 52.5 180 14 7 5.4 2.9
9500 10.5 50.9 185 11 6 4.1 2.3 | 11.7 53.1 180 14 7 4.6 2.5
9250 10.7 51.3 175 12 6 3.1 1.7 | 12.0 53.6 175 14 7 2.9 1.6
9000 11.0 51.8 170 12 6 5.7 3.1 | 12.2 54.0 175 15 8 4.3 2.4
8750 11.5 52.7 165 13 7 8.8 4.8 | 12.6 54.7 170 15 8 5.9 3.3
8500 12.1 53.8 160 14 7 6.3 3.4 | 13.0 55.4 170 15 8 5.7 3.1
8250 12.4 54.3 160 13 7 3.8 2.1 | 13.4 56.1 165 16 8 5.9 3.3
8000 12.7 54.9 155 13 7 4.6 2.5 | 13.9 57.0 165 16 8 6.5 3.6
7750 13.1 55.6 155 13 6 6.1 3.4 | 14.4 57.9 160 16 8 7.1 3.9
7500 13.6 56.5 150 12 6 6.2 3.4 | 15.0 59.0 155 16 8 8.2 4.5
7250 14.1 57.4 150 12 6 5.7 3.1 | 15.7 60.3 155 16 8 9.0 5.0
7000 14.5 58.1 145 12 6 6.4 3.5 | 16.4 61.5 155 16 8 9.0 4.9
6750 15.1 59.2 140 12 6 10.5 5.7 | 17.1 62.8 150 16 8 10.3 5.6
6500 16.0 60.8 140 12 6 11.5 6.3 | 17.9 64.2 150 16 8 10.7 5.9
6250 16.8 62.2 140 11 6 10.5 5.8 | 18.7 65.7 150 15 8 10.7 5.9
6000 17.5 63.5 135 11 6 9.3 5.1 | 19.4 66.9 150 15 8 9.8 5.4
5750 18.3 64.9 135 11 6 14.2 7.8 | 20.2 68.4 145 14 7 10.4 5.7
5500 19.8 67.6 135 10 5 27.1 14.9 | 21.1 70.0 145 12 6 14.9 8.2
________________________________________________________________________________
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 NEAR THE OLD STAPLETON
AIRPORT SITE IN DENVER, COLORADO AT
NORTH LATITUDE: 39 DEG 46 MIN 5.016 SEC
WEST LONGITUDE: 104 DEG 52 MIN 9.984 SEC
ELEVATION: 5285 FEET (1611 METERS)
AND MAY NOT BE REPRESENTATIVE OF OTHER AREAS ALONG THE FRONT RANGE OF THE
COLORADO ROCKY MOUNTAINS. 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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