222
UXUS97 KBOU 161258
SRGBOU
SOARING FORECAST
NATIONAL WEATHER SERVICE DENVER/BOULDER, COLORADO
0657 MDT TUESDAY, SEPTEMBER 16, 2025
THIS FORECAST IS FOR TUESDAY, SEPTEMBER 16, 2025:
IF THE TRIGGER TEMPERATURE OF 78.1 F/25.6 C IS REACHED...THEN
THERMAL SOARING INDEX....................... POOR
MAXIMUM RATE OF LIFT........................ 0 FT/MIN (0.0 M/S)
MAXIMUM HEIGHT OF THERMALS.................. 8973 FT MSL (3638 FT AGL)
FORECAST MAXIMUM TEMPERATURE................... 77.0 F/25.5 C
TIME OF TRIGGER TEMPERATURE.................... NONE
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................. 7451 FT MSL (2116 FT AGL)
THERMAL SOARING OUTLOOK FOR WEDNESDAY 09/17.... FAIR
WAVE SOARING INDEX............................. POOR
WAVE SOARING INDEX TREND (TO 1800 MDT)......... NO CHANGE
HEIGHT OF STABLE LAYER (12-18K FT MSL)......... NONE
WEAK PVA/NVA (THROUGH 1800 MDT)................ WEAK PVA
POTENTIAL HEIGHT OF WAVE....................... 27757 FT MSL (22422 FT AGL)
WAVE SOARING OUTLOOK FOR WEDNESDAY 09/17....... POOR
REMARKS... AFTERNOON SHOWERS AND THUNDERSTORMS
SUNRISE/SUNSET.................... 06:42:06 / 19:06:14 MDT
TOTAL POSSIBLE SUNSHINE........... 12 HR 24 MIN 8 SEC (744 MIN 8 SEC)
ALTITUDE OF SUN AT 12:54:10 MDT... 52.53 DEGREES
UPPER AIR DATA FROM NUMERICAL MODEL FORECAST VALID ON 09/16/2025 AT 0600 MDT
FREEZING LEVEL.................. 14788 FT MSL (9453 FT AGL)
CONVECTIVE CONDENSATION LEVEL... 16570 FT MSL (11235 FT AGL)
LIFTED CONDENSATION LEVEL....... 15188 FT MSL (9853 FT AGL)
LIFTED INDEX.................... -1.1
K INDEX......................... +23.3
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 -58.8 -73.8 275 22 11 3.1 1.7 M M M M M
45000 -55.1 -67.2 270 36 18 0.2 0.1 M M M M M
40000 -54.8 -66.6 265 42 22 0.9 0.5 M M M M M
38000 -53.0 -63.4 260 41 21 3.1 1.7 M M M M M
36000 -50.9 -59.6 255 41 21 3.2 1.7 M M M M M
34000 -47.2 -53.0 255 39 20 7.5 4.1 M M M M M
32000 -42.7 -44.9 255 36 19 7.6 4.1 M M M M M
30000 -38.1 -36.6 255 32 17 7.8 4.3 36.8 98.2 8.9 M M
29000 -35.8 -32.4 250 30 15 7.8 4.3 36.0 96.8 8.4 M M
28000 -33.4 -28.1 245 28 14 7.8 4.3 35.4 95.7 8.0 M M
27000 -31.0 -23.8 245 26 13 8.4 4.6 34.7 94.5 7.6 M M
26000 -28.4 -19.1 240 25 13 8.4 4.6 34.2 93.6 7.3 M M
25000 -25.9 -14.6 235 23 12 8.4 4.6 33.8 92.8 7.0 M M
24000 -23.5 -10.3 230 22 11 7.9 4.3 33.1 91.6 6.6 M M
23000 -21.2 -6.2 225 20 10 7.9 4.3 32.4 90.3 6.0 M M
22000 -18.8 -1.8 220 19 10 7.9 4.3 31.8 89.3 5.6 M M
21000 -16.5 2.3 215 17 9 8.0 4.4 31.1 88.0 5.0 M M
20000 -14.1 6.6 215 15 8 8.1 4.4 30.5 86.9 4.4 M M
19500 -12.4 9.7 210 14 7 8.2 4.5 30.1 86.2 4.1 M M
19000 -11.2 11.8 210 14 7 8.9 4.9 29.9 85.8 3.9 M M
18500 -9.9 14.2 205 14 7 8.9 4.9 29.7 85.5 3.7 M M
18000 -8.6 16.5 205 14 7 9.0 4.9 29.6 85.3 3.6 M M
17500 -7.2 19.0 205 14 7 9.0 4.9 29.5 85.0 3.5 M M
17000 -5.9 21.4 205 13 7 9.1 5.0 29.3 84.8 3.4 M M
16500 -4.5 23.9 205 13 7 9.3 5.1 29.2 84.6 3.3 M M
16000 -3.2 26.2 205 13 7 9.3 5.1 29.2 84.5 3.2 M M
15500 -1.8 28.8 210 12 6 9.2 5.1 29.1 84.3 3.1 M M
15000 -0.4 31.3 210 12 6 9.2 5.1 29.0 84.2 3.0 M M
14500 0.9 33.6 210 12 6 9.1 5.0 28.9 84.0 3.0 M M
14000 2.3 36.1 215 11 6 9.0 5.0 28.8 83.8 2.9 M M
13500 3.6 38.5 220 11 6 9.0 4.9 28.7 83.6 2.8 M M
13000 4.9 40.8 220 10 5 8.9 4.9 28.5 83.3 2.6 M M
12500 6.3 43.3 225 10 5 8.7 4.8 28.4 83.1 2.5 M M
12000 7.5 45.5 230 9 5 8.4 4.6 28.2 82.7 2.3 M M
11500 8.8 47.8 230 8 4 8.4 4.6 28.0 82.4 2.1 M M
11000 10.0 50.0 240 8 4 7.9 4.3 27.7 81.9 1.9 M M
10500 11.1 52.0 250 7 4 5.7 3.1 27.5 81.4 1.6 M M
10250 11.4 52.5 255 7 4 4.2 2.3 27.0 80.6 1.2 M M
10000 11.9 53.4 260 7 3 8.0 4.4 26.7 80.1 0.9 M M
9750 12.6 54.7 270 6 3 9.5 5.2 26.7 80.0 0.8 M M
9500 13.2 55.8 280 6 3 7.7 4.2 26.6 79.9 0.8 M M
9250 13.7 56.7 290 6 3 4.2 2.3 26.3 79.3 0.5 M M
9000 14.0 57.2 300 7 4 4.9 2.7 25.8 78.5 0.1 M M
8750 14.4 57.9 310 7 4 7.4 4.0 25.6 78.1 -0.2 237 1.2
8500 14.9 58.8 320 8 4 4.7 2.6 25.3 77.6 -0.5 216 1.1
8250 15.1 59.2 330 9 4 1.8 1.0 24.8 76.7 -1.0 202 1.0
8000 15.2 59.4 335 10 5 2.1 1.2 24.2 75.6 -1.6 191 1.0
7750 15.4 59.7 340 10 5 3.6 2.0 23.7 74.6 -2.1 178 0.9
7500 15.6 60.1 345 10 5 1.3 0.7 23.2 73.7 -2.7 165 0.8
7250 15.6 60.1 345 11 6 -1.2 -0.7 22.4 72.2 -3.5 159 0.8
7000 15.5 59.9 350 12 6 -0.3 -0.2 21.6 70.8 -4.3 154 0.8
6750 15.4 59.7 350 12 6 0.1 0.1 20.8 69.5 -5.1 148 0.8
6500 15.4 59.7 345 10 5 -0.8 -0.5 20.1 68.1 -5.9 142 0.7
6250 15.2 59.4 340 10 5 -1.8 -1.0 19.2 66.6 -6.8 139 0.7
6000 15.1 59.2 340 9 4 -1.5 -0.8 18.3 65.0 -7.7 136 0.7
5750 14.9 58.8 340 9 5 -4.9 -2.7 17.4 63.3 -8.6 135 0.7
5500 14.3 57.7 325 6 3 -10.2 -5.6 16.1 61.0 -9.9 145 0.7
* * * * * * NUMERICAL WEATHER PREDICTION MODEL FORECAST DATA VALID * * * * * *
09/16/2025 AT 0900 MDT | 09/16/2025 AT 1200 MDT
|
CAPE... 0.0 LI... -0.1 | CAPE... +306.4 LI... -0.5
CINH... 0.0 K INDEX... +22.4 | CINH... -137.9 K INDEX... +21.4
|
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 -58.5 -73.3 270 21 11 3.1 1.7 | -57.9 -72.2 270 21 11 2.4 1.3
45000 -54.6 -66.3 265 33 17 0.4 0.2 | -54.8 -66.6 270 34 18 0.7 0.4
40000 -54.1 -65.4 260 41 21 0.9 0.5 | -53.7 -64.7 260 49 25 1.2 0.7
38000 -52.6 -62.7 255 43 22 2.5 1.4 | -52.1 -61.8 260 45 23 2.8 1.5
36000 -50.9 -59.6 250 45 23 2.6 1.4 | -50.2 -58.4 255 39 20 2.8 1.5
34000 -47.5 -53.5 245 40 21 7.1 3.9 | -47.2 -53.0 250 35 18 6.1 3.3
32000 -43.3 -45.9 245 33 17 7.1 3.9 | -43.6 -46.5 235 31 16 6.1 3.3
30000 -38.6 -37.5 240 30 15 8.3 4.5 | -39.0 -38.2 230 30 15 8.4 4.6
29000 -36.1 -33.0 235 29 15 8.3 4.5 | -36.5 -33.7 230 29 15 8.4 4.6
28000 -33.6 -28.5 230 29 15 8.3 4.6 | -34.1 -29.4 225 29 15 8.4 4.6
27000 -31.2 -24.2 230 28 14 8.1 4.4 | -31.6 -24.9 225 28 14 8.3 4.5
26000 -28.8 -19.8 225 26 14 8.1 4.4 | -29.1 -20.4 225 26 14 8.3 4.5
25000 -26.4 -15.5 225 25 13 8.0 4.4 | -26.6 -15.9 225 25 13 8.3 4.5
24000 -23.9 -11.0 220 24 12 8.3 4.5 | -24.1 -11.4 225 23 12 8.5 4.7
23000 -21.4 -6.5 220 23 12 8.3 4.5 | -21.6 -6.9 225 21 11 8.5 4.7
22000 -19.0 -2.2 215 21 11 8.4 4.6 | -19.0 -2.2 220 19 10 8.6 4.7
21000 -16.6 2.1 210 19 10 7.9 4.3 | -16.6 2.1 220 18 9 7.9 4.4
20000 -14.3 6.3 205 18 9 8.0 4.4 | -14.2 6.4 215 17 9 8.0 4.4
19500 -13.1 8.4 205 17 9 8.0 4.4 | -13.1 8.4 215 16 8 8.0 4.4
19000 -11.3 11.7 200 16 8 8.6 4.7 | -11.9 10.6 215 16 8 8.2 4.5
18500 -10.1 13.8 200 15 8 8.6 4.7 | -10.1 13.8 215 15 8 8.3 4.5
18000 -8.8 16.2 200 15 7 8.7 4.8 | -8.9 16.0 215 14 7 8.6 4.7
17500 -7.5 18.5 200 14 7 8.7 4.8 | -7.6 18.3 215 14 7 8.8 4.8
17000 -6.2 20.8 200 14 7 8.8 4.8 | -6.3 20.7 215 13 7 8.8 4.8
16500 -4.9 23.2 205 13 7 8.9 4.9 | -5.0 23.0 220 12 6 8.5 4.7
16000 -3.6 25.5 205 13 7 8.9 4.9 | -3.8 25.2 225 12 6 8.6 4.7
15500 -2.3 27.9 210 12 6 9.1 5.0 | -2.5 27.5 230 11 6 8.3 4.6
15000 -0.9 30.4 210 12 6 9.1 5.0 | -1.3 29.7 235 11 6 8.3 4.6
14500 0.4 32.7 215 11 6 8.7 4.8 | -0.0 32.0 240 10 5 8.9 4.9
14000 1.7 35.1 225 10 5 8.7 4.7 | 1.3 34.3 245 10 5 9.0 5.0
13500 3.0 37.4 230 10 5 8.5 4.7 | 2.6 36.7 250 10 5 9.0 4.9
13000 4.2 39.6 235 9 5 8.5 4.6 | 4.0 39.2 255 10 5 8.9 4.9
12500 5.5 41.9 245 9 5 8.4 4.6 | 5.3 41.5 260 10 5 8.8 4.8
12000 6.7 44.1 250 8 4 8.2 4.5 | 6.6 43.9 260 9 5 8.6 4.7
11500 7.9 46.2 255 8 4 8.1 4.4 | 7.9 46.2 265 8 4 8.4 4.6
11000 9.1 48.4 265 7 4 7.7 4.2 | 9.0 48.2 270 7 4 7.6 4.2
10500 10.3 50.5 280 7 3 5.3 2.9 | 10.2 50.4 275 6 3 4.8 2.6
10250 10.5 50.9 280 7 4 3.6 2.0 | 10.4 50.7 275 7 3 3.8 2.1
10000 10.9 51.6 290 7 4 8.2 4.5 | 10.9 51.6 280 6 3 8.7 4.8
9750 11.6 52.9 300 7 4 10.2 5.6 | 11.6 52.9 285 5 3 10.2 5.6
9500 12.3 54.1 310 7 4 7.4 4.1 | 12.3 54.1 295 5 2 7.1 3.9
9250 12.7 54.9 315 8 4 3.4 1.9 | 12.6 54.7 305 5 2 2.1 1.2
9000 13.0 55.4 320 8 4 4.6 2.5 | 12.8 55.0 315 5 3 4.3 2.4
8750 13.4 56.1 325 9 5 7.0 3.8 | 13.2 55.8 330 5 3 7.0 3.8
8500 13.8 56.8 330 10 5 4.2 2.3 | 13.6 56.5 340 6 3 5.4 2.9
8250 14.0 57.2 335 11 6 1.9 1.0 | 13.9 57.0 345 6 3 4.1 2.3
8000 14.1 57.4 335 12 6 2.4 1.3 | 14.2 57.6 350 7 4 5.1 2.8
7750 14.3 57.7 335 13 6 2.1 1.1 | 14.7 58.5 355 7 4 6.7 3.7
7500 14.3 57.7 330 13 7 0.1 0.1 | 15.1 59.2 355 8 4 6.6 3.6
7250 14.2 57.6 330 13 7 -1.0 -0.6 | 15.6 60.1 360 8 4 5.8 3.2
7000 14.1 57.4 330 13 7 -1.2 -0.7 | 16.0 60.8 360 8 4 7.1 3.9
6750 14.1 57.4 330 13 7 1.3 0.7 | 16.6 61.9 360 8 4 11.6 6.4
6500 14.3 57.7 330 11 6 4.7 2.6 | 17.6 63.7 360 8 4 11.9 6.5
6250 14.7 58.5 325 10 5 5.4 2.9 | 18.4 65.1 360 8 4 10.8 5.9
6000 15.0 59.0 325 9 4 3.3 1.8 | 19.2 66.6 005 8 4 8.7 4.8
5750 15.3 59.5 320 8 4 8.0 4.4 | 19.9 67.8 005 8 4 14.2 7.8
5500 16.5 61.7 315 7 3 21.7 11.9 | 21.6 70.9 005 7 4 31.3 17.2
09/16/2025 AT 1500 MDT | 09/16/2025 AT 1800 MDT
|
CAPE... +772.1 LI... -2.6 | CAPE... +477.6 LI... -1.8
CINH... -20.6 K INDEX... +25.6 | CINH... -22.8 K INDEX... +29.3
|
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 -57.7 -71.9 275 20 10 3.2 1.8 | -58.3 -72.9 280 19 10 3.4 1.8
45000 -53.8 -64.8 275 32 16 0.2 0.1 | -54.2 -65.6 270 28 14 0.1 0.0
40000 -53.6 -64.5 265 57 29 1.8 1.0 | -54.1 -65.4 260 48 25 0.9 0.5
38000 -52.0 -61.6 265 55 28 2.6 1.4 | -52.5 -62.5 250 45 23 2.9 1.6
36000 -50.4 -58.7 260 53 27 2.6 1.4 | -50.5 -58.9 240 42 22 3.0 1.6
34000 -47.2 -53.0 260 48 25 7.0 3.8 | -46.7 -52.1 235 39 20 7.8 4.3
32000 -43.1 -45.6 255 42 21 7.0 3.8 | -42.1 -43.8 235 35 18 7.8 4.3
30000 -38.5 -37.3 250 38 19 8.1 4.5 | -37.1 -34.8 230 33 17 8.6 4.7
29000 -36.0 -32.8 250 36 19 8.2 4.5 | -34.5 -30.1 230 31 16 8.6 4.7
28000 -33.0 -27.4 250 35 18 8.2 4.5 | -31.9 -25.4 230 30 15 8.6 4.7
27000 -30.5 -22.9 245 33 17 8.5 4.7 | -29.4 -20.9 230 29 15 8.2 4.5
26000 -28.0 -18.4 245 31 16 8.5 4.7 | -27.0 -16.6 235 28 14 8.2 4.5
25000 -25.4 -13.7 245 29 15 8.6 4.7 | -24.5 -12.1 235 26 14 8.3 4.5
24000 -23.1 -9.6 240 27 14 7.8 4.3 | -22.2 -8.0 240 26 13 7.3 4.0
23000 -20.8 -5.4 235 24 13 7.8 4.3 | -20.1 -4.2 240 25 13 7.3 4.0
22000 -18.5 -1.3 230 22 11 7.9 4.3 | -17.9 -0.2 240 24 12 7.4 4.1
21000 -16.2 2.8 230 20 10 7.7 4.2 | -15.8 3.6 240 23 12 7.3 4.0
20000 -13.9 7.0 230 17 9 7.7 4.2 | -13.6 7.5 240 21 11 7.3 4.0
19500 -12.8 9.0 230 16 8 7.7 4.2 | -12.6 9.3 235 20 10 7.3 4.0
19000 -11.6 11.1 225 15 8 7.7 4.2 | -11.0 12.2 235 19 10 7.1 3.9
18500 -10.5 13.1 225 15 8 7.7 4.2 | -9.9 14.2 230 18 9 7.2 3.9
18000 -9.4 15.1 225 14 7 7.7 4.2 | -8.9 16.0 230 17 9 7.1 3.9
17500 -8.3 17.1 225 13 7 7.4 4.1 | -7.8 18.0 225 17 9 7.1 3.9
17000 -7.2 19.0 225 12 6 7.4 4.1 | -6.8 19.8 225 16 8 7.1 3.9
16500 -6.1 21.0 225 11 6 8.2 4.5 | -5.8 21.6 220 15 8 6.9 3.8
16000 -4.9 23.2 225 10 5 8.2 4.5 | -4.8 23.4 220 14 7 6.9 3.8
15500 -3.6 25.5 225 9 5 8.4 4.6 | -3.8 25.2 215 13 7 6.7 3.7
15000 -2.4 27.7 230 8 4 8.6 4.7 | -2.9 26.8 210 12 6 6.7 3.7
14500 -1.1 30.0 230 7 4 8.4 4.6 | -1.9 28.6 205 11 6 6.7 3.7
14000 0.6 33.1 240 5 3 7.7 4.3 | -0.9 30.4 205 10 5 6.8 3.7
13500 1.7 35.1 250 4 2 8.5 4.7 | 0.1 32.2 200 9 5 7.1 3.9
13000 3.0 37.4 260 3 2 9.0 4.9 | 1.2 34.2 195 8 4 7.6 4.1
12500 4.3 39.7 275 2 1 9.0 5.0 | 2.3 36.1 190 7 4 7.7 4.2
12000 5.7 42.3 295 2 1 9.0 4.9 | 3.4 38.1 185 6 3 8.0 4.4
11500 7.0 44.6 330 1 1 8.8 4.8 | 4.6 40.3 175 4 2 8.0 4.4
11000 8.2 46.8 360 2 1 8.1 4.4 | 5.8 42.4 165 3 2 8.0 4.4
10500 9.5 49.1 015 3 2 3.5 1.9 | 7.0 44.6 145 2 1 6.4 3.5
10250 9.5 49.1 360 4 2 3.9 2.1 | 7.4 45.3 150 2 1 5.6 3.1
10000 10.2 50.4 005 5 3 11.1 6.1 | 7.9 46.2 145 1 1 9.3 5.1
9750 10.9 51.6 015 6 3 10.8 5.9 | 8.7 47.7 105 1 1 10.6 5.8
9500 11.7 53.1 020 8 4 8.2 4.5 | 9.4 48.9 070 1 1 9.4 5.1
9250 12.1 53.8 015 9 4 5.0 2.7 | 10.0 50.0 050 1 1 7.6 4.2
9000 12.6 54.7 015 9 5 9.4 5.1 | 10.6 51.1 025 1 1 8.6 4.7
8750 13.4 56.1 015 10 5 12.7 7.0 | 11.3 52.3 025 1 1 9.8 5.4
8500 14.2 57.6 020 10 5 9.4 5.2 | 12.0 53.6 020 1 1 9.1 5.0
8250 14.8 58.6 015 11 6 6.2 3.4 | 12.6 54.7 005 2 1 8.8 4.8
8000 15.3 59.5 010 11 6 9.7 5.3 | 13.3 55.9 350 2 1 8.7 4.8
7750 16.2 61.2 015 11 6 12.8 7.0 | 13.9 57.0 340 2 1 8.5 4.7
7500 17.0 62.6 015 12 6 9.4 5.2 | 14.5 58.1 330 2 1 8.3 4.6
7250 17.6 63.7 010 12 6 6.5 3.6 | 15.1 59.2 325 2 1 8.2 4.5
7000 18.2 64.8 010 12 6 9.6 5.2 | 15.7 60.3 320 3 1 8.5 4.6
6750 19.0 66.2 010 12 6 13.4 7.4 | 16.3 61.3 315 3 2 9.4 5.1
6500 20.0 68.0 010 12 6 11.5 6.3 | 17.0 62.6 310 3 2 9.6 5.2
6250 20.7 69.3 010 12 6 10.4 5.7 | 17.7 63.9 310 3 2 8.8 4.8
6000 21.5 70.7 005 12 6 8.3 4.5 | 18.4 65.1 305 3 2 10.4 5.7
5750 22.2 72.0 005 12 6 13.5 7.4 | 19.3 66.7 305 3 2 12.8 7.0
5500 23.8 74.8 005 11 6 30.0 16.5 | 20.2 68.4 310 3 2 12.5 6.9
________________________________________________________________________________
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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